Abstract
Selected Oral Presentations
DBA Data Blitz A: Mini Presentations
SIGNIFICANT EPIDEMIOLOGICAL CHANGES IN CERVICAL SPINAL CORD INJURIES IN THE STATE OF MARYLAND OVER AN 18‐YEAR PERIOD
University of Maryland School of Medicine, Neurosurgery, Baltimore, USA
Cross‐sectional analysis of longitudinal data from Spinal Cord Injury Model Systems during the past 40 years analyzing over 30,000 traumatic spinal cord injuries (SCIs) have indicated that patients with SCI are getting older and the proportion of falls and incomplete SCI is increasing. The demographics, injury mechanism, AIS grade, ASIA motor score, intramedullary lesion length (IMLL), and hematomyelia on the admission MRI of 1251 patients who were admitted to the Shock Trauma Center with cervical SCI were analyzed for time trend change over an 18‐year period. During this period the incidence of cervical SCI in the state of Maryland did not change significantly. In this study, 78.7 percent of patients were male. Injury mechanism in 47.3 percent was due to falls, 33.6 percent due to motor vehicle collisions (MVCs), and 11.6 percent sport injuries. Miscellaneous causes were noted in 7.5 percent of patients. Close to 30 percent of injuries were complete (AIS grade A), and mean ASIA motor score was 45.3. Mean IMLL was 36.7 mm, and 35.8 percent of patients had evidence of hematomyelia on the admission MRI. From 2001 to 2018, the proportion of cervical SCIs caused by MVCs and the proportion of complete injuries decreased notably while age and motor score increased. These observed changes were not due to a change in referral patterns to University of Maryland, which remained steady during the study period (p for trend = 0.8). Mean IMLL and proportion of injuries with hematomyelia did not change significantly during this period. To determine whether the observed changes were independent of one another, we ran a series of regression models. For each factor that significantly increased or decreased during the study period, we tested the time trend, adjusting for all other factors. Time trends for age, MVC, and complete injury remained significant and in the same direction following adjustment for other factors. The time trend for motor score was no longer significant following adjustment.
Keywords: Spinal Cord Injury, Epidemiology, Time Trend, Cross Sectional Study, Longitudinal Study, Intramedullary Lesion Length
LONG TERM PROGNOSIS OF SEVERE TRAUMATIC BRAIN INJURED PATIENTS USING ACUTE PHASE NEUROPHYSIOLOGY TESTING
University of Pittsburgh School of Medicine, Neurosurgery, Pittsburgh, USA
Keywords: Neurophysiology, Outcomes, Severe, Prognosis
GUT MICROBIOTA DYSBIOSIS EXACERBATES HIPPOCAMPAL NEURONAL LOSS AND MALADAPTIVE FEAR MEMORY RESPONSE FOLLOWING TBI
Washington University in St. Louis School of Medicine, Pediatrics, St Louis, USA
The influence of the gut microbiota on traumatic brain injury (TBI), tissue repair, and subsequent neurological outcome is presently unknown. This knowledge gap is of paramount clinical significance as TBI patients are highly susceptible to alterations in the gut microbiota due to frequent antibiotic administration, prolonged hospitalization, and autonomic dysfunction. To induce microbial dysbiosis, mice were randomized to drinking water with broad spectrum antibiotics (vancomycin, neomycin, ampicillin, and metronidazole: VNAM) dissolved in Kool‐aid or Kool‐aid alone as control. Two weeks later, mice were randomized to controlled cortical impact or sham surgery with or without continuation of antibiotics post‐injury. Contextual fear conditioning and testing were performed on post‐injury days 5‐7 with sacrifice 90 minutes after testing on post‐injury day 7. As expected, we found microbial dysbiosis as determined by 16S sequencing and loss of gut epithelial integrity in animals treated with antibiotics. Importantly, we found increased neuronal cell loss in the ipsilateral (IL) CA3 region of the hippocampus in antibiotic treated mice 7 days after injury. We further characterized this cell loss and, specifically, found fewer parvalbumin GABAergic inhibitory interneurons in the IL hippocampi of the injured mice exposed to VNAM. Additionally, we observed increased c‐Fos staining in the IL ventral hippocampi of injured, VNAM treated mice. Furthermore, we found a maladaptive fear memory response with increased contextual freezing response in uninjured, VNAM treated mice compared to the sham controls. Importantly, we also observed an increased contextual freezing response in the injured, VNAM treated mice compared to both the injured/uninjured non‐antibiotic treated mice. Given our hypothesis that microbiota dysbiosis leads to poor outcomes after TBI via microbial‐host immune interactions, further studies are investigating the peripheral and/or local immunological environment and subsequent effect on tissue repair after TBI.
Keywords: gut microbiota, dysbiosis, fear memory, traumatic brain injury, inhibitory neurons
SALIVARY NON‐CODING RNAS: THE NEXT GENERATION OF BIOMARKERS IN CONCUSSED RUGBY FOOTBALL UNION PLAYERS
1University of Birmigham, Birmingham, UK
2Queen Elizabeth Hospitals, Birmingham, UK
3MiRNA diagnostics ltd, Birmingham, UK
4University of Cambridge, Cambridge, UK
5University of Bath, Bath, UK
6RFU, London, UK
7Premiership Rugby Ltd, London, UK
The Study of Concussion in Rugby Union through MicroRNAs (SCRUM) is a prospective observational study of players participating in the two highest tiers of senior professional male domestic rugby competition in England, the Premiership and Championship. The study was embedded within the ongoing Rugby Football Union Injury Surveillance Programme for the 2017‐2018 season. As defined in the Head Injury Assessment protocol, whenever a player suffered a head impact event with either clear/immediate signs of concussion OR with the potential for concussion, they were asked to provide saliva samples at the following timepoints: during the game (HIA1), post‐match (HIA2) and at 36‐48 hours following the game (HIA3). This created 2 categories of player suffering a head impact event; 1. Those with clear/immediate signs of concussion or diagnosed with concussion after multi‐timepoint clinical assessment and 2. Those in whom concussion was excluded after multi‐timepoint clinical assessment. In addition, uninjured control players and players removed from the game with other musculoskeletal trauma were asked to provide samples at the HIA2 and HIA3 timepoints in order to exclude contamination from non‐neurological injuries and orthopaedic‐trauma.
An initial discovery‐set of 60 samples was evaluated through next generation sequencing. A panel of 94 small non‐coding RNAs (sncRNAs) survived to an FDR <0.05 or p‐value <0.05, comparing concussions and controls. The selected panel, was used for a validation study on 598 samples, by qPCR. When comparing the groups, 21 sncRNAs were found to be differentially expressed with p‐value <0.05, four of which survive the Benjamini‐Hochberg correction at a significance level of 0.05. These biomarkers can provide a novel, non‐invasive way to support the diagnosis of concussion.
Keywords: microRNA, salivary biomarkers, Rugby Football Union
DISRUPTIONS IN HIPPOCAMPAL CIRCUITRY INVOLVED IN LEARNING AND MEMORY FOLLOWING TBI
1University of Pennsylvania, Department of Neurosurgery, Philadelphia, USA
2Corporal Michael J. Crescenz VA Medical Center, Philadelphia, USA
Hippocampal‐dependent memory loss is a common and persistent sequela following TBI, but the mechanisms underlying memory impairment are poorly understood. Previous studies using the fluid percussion injury (FPI) model have reported a loss of power in frequency‐bands necessary for the organization of neuronal ensembles that underlie spatial memory tasks. Learning and memory impairment following TBI may be due in part to communication disruptions within the hippocampus via altered neuronal oscillations and disorganized ensemble activity. To examine these potential mechanisms, rats were chronically implanted in the hippocampus with 64 channel silicon probes following injury, which allowed for recordings of single units and simultaneous laminar field potentials. Wireless recordings were performed while the animal was exploring a familiar and a novel environment to examine the effects of injury on the formation/organization of neuronal ensembles during memory encoding and retrieval. Preliminary results show that place cells are formed in rodents post‐injury, but these neurons show a reduction in spatial specificity. Importantly, CA1 firing rates remain unchanged compared to sham, suggesting disorganized timing. An entrainment analysis of single unit timing to oscillations involved in the organization of neuronal ensembles such as theta (4‐12 Hz) and high gamma (60‐110 Hz) showed a shift in phase preference in injured animals. This entrainment is coordinated by input from the entorhinal cortex and CA3 region. A laminar analysis showed a loss in the phase‐amplitude coupling of these oscillations at all levels of the dendritic arbor. Interestingly, the differences in entrainment to the theta oscillation specifically during encoding of memory is lost in the injured animal. Radial arm maze testing showed that rats were able to remember a previously learned pattern of rewards post‐injury, but were unable to encode a new pattern. These reductions in oscillatory power, as well as the disordered timing of CA1 unit firing, may disrupt hippocampal encoding leading to learning and memory deficits post injury.
Keywords: hippocampus, diffuse axonal injury, spatial memory, Electrophysiology
MICROGLIA ELIMINATION RECOVERED PERIPHERAL INFLAMMATION‐INDUCED SLEEP BUT PROLONGED TBI‐INDUCED SLEEP IN MICE
1University of Arizona COM‐Phoenix, Phoenix, USA
2Barrow Neurological Institute at Phoenix Children's Hospital, Phoenix, USA
3University of Arizona College of Nursing, Tucson, USA
4Phoenix VA Healthcare System, Phoenix, USA
Sleep is regulated by physiological processes such that inflammation and cytokine production may disrupt the signaling required to maintain a healthy sleep profile. Traumatic brain injury (TBI) evokes inflammation and microglia activation, with subsequent sleep disturbances that can exacerbate inflammation and neurological symptoms after TBI. As such, a dynamic feedback loop connects sleep, inflammation, and TBI. We hypothesized that microglia elimination with a CSF‐1R inhibitor (PLX5622) would attenuate cytokine levels and differentially regulate sleep after peripheral‐induced and TBI‐induced inflammation. Mice were administered PLX5622 or control diet (21d) and baseline sleep was measured. PLX5622 eliminated microglia (< 0.5% remained) without significant differences in physiological sleep or peripheral cytokine levels (IL‐6, TNF‐α, IL‐1β) compared to control diet. Mice on PLX5622 and control diet received lipopolysaccharide (LPS;1.2mg/kg i.p) or midline fluid percussion injury (mFPI) and sleep was recorded for 3 days. LPS increased sleep (cumulative minutes/day) regardless of diet (F(1,8) = 11.28, p < 0.01). In LPS mice on control diet, sleep remained increased. In mice on PLX5622, sleep returned to baseline by day 3 post‐injection, with elevated peripheral IL‐6 at day 1 post‐injection (F(2,10) = 25.99, p < 0.0001). TBI increased sleep regardless of diet (F(1,4) = 17.91, p < 0.01). In mFPI mice on control diet, sleep returned to baseline by day 2 post‐injury. In mFPI mice on PLX5622, sleep remained higher than baseline over 3 days post‐injury. Regardless of diet, peripheral cytokine levels were not elevated (1 day post‐injury). Thus, microglia elimination recovered sleep disturbances after peripheral‐induced inflammation, but prolonged sleep disturbances after TBI, which establishes a role for microglia in the feedback loop among sleep, inflammation, and TBI. Microglia represent a plausible therapeutic target to mitigate inflammation, using sleep outcomes as a pharmacodynamic measure in treating TBI and other neuroinflammatory diseases.
Funding: PCH‐Mission‐Support
Keywords: Sleep, Microglia, Inflammation, Midline fluid percussion injury, Mouse
GLIAL FIBRILLARY ACIDIC PROTEIN LEVELS RELATE TO CHANGES IN NEUROIMAGING FINDINGS AFTER MILD TRAUMATIC BRAIN INJURY
National Institutes of Health, Bethesda, USA
Mild traumatic brain injury (mTBI) is associated with variable clinical outcomes and might result in lasting symptoms. Subtle signs of injury that are not seen on CT scans can be detected via MRI, including diffuse axonal injury, which is associated with higher risks for neurologic symptoms. However, MRI is often not available or financially viable in clinical settings. Thus, identifying biomarkers that relate to MRI findings would aid clinicians in injury assessment, mitigating the costs of MRI and allowing for the development of precise treatment models. We aimed to determine whether the blood‐based biomarkers glial fibrillary acidic protein (GFAP), tau, and neurofilament light chain (NFL) can discriminate between mTBI patients who do and do not recover from MRI‐identified injuries. Study participants (n = 157) presented to the emergency department with history of head injury and suspected mTBI. Blood collection and MRI imaging were performed within 48 hours of injury and up to 7 days after the mTBI. Participants were classified into two groups according to MRI findings: MRI‐persistent (MRI‐positive at both timepoints, n = 127) and MRI‐recovered (MRI‐positive at baseline and MRI‐negative at follow‐up, n = 30). Plasma samples were analyzed using an ultrasentive assay. Concentrations of plasma GFAP were significantly higher in the MRI‐persistent group compared to the MRI‐recovered group at baseline (p = .007) and at follow‐up (p = .001). Levels of tau and NFL did not differ significantly between groups. GFAP was a poor method for distinguishing groups at baseline (AUC 0.66; 95% CI 0.54‐0.79), but satisfactory at follow‐up (AUC 0.77; 95% CI 0.69‐0.86). Our findings suggest the potential of blood GFAP as a marker of brain abnormalities in patients with acute mTBI. This biomarker strategy could prove valuable in the stratification of patients in clinical trials and to guide clinical decisions. Funding: NINR, NINDS, CNRM.
Keywords: axonal injury, MRI, blood, postconcussive symptoms
MTOR PATHWAY ACTIVATION IMPLICATED IN EPILEPTOGENESIS AFTER TBI
1University of Pennsylvania, Neurosurgery, Philadelphia, USA
2Queen Elizabeth University Hospital, Neuropathology, Glasgow, Scotland
3University of Pennsylvania, Neurology, Philadelphia, USA
Post‐traumatic epilepsy (PTE) represents a debilitating complication of traumatic brain injury (TBI). The mammalian target of rapamycin (mTOR) pathway is increasingly implicated in various genetic and acquired epilepsies, with compelling data supporting a role in epileptogenesis. Notably, mTOR activation has also been reported following rodent models of TBI in association with mossy fiber sprouting and PTE, both of which were mitigated by mTOR inhibition via rapamycin. However, the role of mTOR in human post‐traumatic epileptogenesis is unknown. Here, we examine mTOR pathway activation using post‐mortem tissue from the Glasgow TBI Archive from individuals with a history of PTE (n = 31), severe TBI without epilepsy (n = 37; survival 2wks‐12yrs), epilepsy without TBI history (n = 26) and controls (n = 26). Immunohistochemistry specific for markers of mTOR activation (pS6‐ser235‐236 and pS6‐ser240‐244) was performed and findings semiquantitatively scored within hippocampus. Mossy fiber sprouting was examined via dynorphin staining. A subset of PTE cases demonstrated marked immunoreactivity for pS6‐ser235‐236 and pS6‐ser240‐244 in the dentate granule cells, compared with normal controls (p < 0.05), and was comparable to that in non‐trauma‐associated epilepsy. Importantly, a subset of TBI cases without epilepsy also displayed increased immunoreactivity for pS6‐ser240‐244 across the survival range (p < 0.05 vs controls). Yet, curiously, pS6‐ser235‐236 immunoreactivity was not increased in this group. While pS6‐ser240‐244 is mTOR pathway‐specific, pS6‐ser235‐236 is also driven by mTOR‐independent pathways and may account for differential findings. Mossy fiber sprouting was more frequent in all groups versus controls (p < 0.05) and was associated with mTOR activation. However, this was not absolute, with sprouting in the absence of mTOR activation observed in some cases. These data indicate mTOR activation may be an important feature in some cases of PTE. Given the recognition that the mTOR pathway contributes to epileptogenesis, the observed mTOR activation in TBI without epilepsy suggests this may also be of mechanistic significance in post‐traumatic epileptogenesis. Funding: CURE‐TAPTE Grant
Keywords: TBI, Post Traumatic Epilepsy, Hippocampus, mTOR
EXPLORING ADDITIONAL APPROACHES TO THERAPY RANKING IN OPERATION BRAIN TRAUMA THERAPY
1Safar Center for Resuscitation Research, Univ. of Pittsburgh, Department of Critical Care Medicine, Pittsburgh, USA
2University of Miami, School of Medicine, MIami, USA
3Walter Reed Army Institute of Research, Silver Spring, USA
4Messina University, Messina, Italy
5Virginia Commonwealth University, Richmond, USA
6University of Florida, Gainesville, USA
7Banyan Biomarkers, Alachua, USA
Operation brain trauma therapy (OBTT) is a multicenter pre‐clinical therapy and biomarker screening consortium. It screened 12 therapies (nicotinamide, erythropoietin, cyclosporine, simvastatin, levetiracetam, glibenclamide, Kollidon VA‐64, AER‐271, amantadine, minocycline, E64d and P7C3‐A20) in >1500 rats across three TBI models (parasagittal fluid percussion [FPI], controlled cortical impact [CCI], and penetrating ballistic‐like brain injury [PBBI]). We assigned 22‐points per model across behavioral and histological outcomes, generating an overall score for each therapy. Levetiracetam and glibenclamide ranked the highest. We now take two additional therapy ranking approaches. First we examined therapeutic efficacy within models. Second, to maximize positive signals, we examined the impact of eliminating negative points. Several findings emerged. Using a minimum threshold of ≥+3‐points to reflect efficacy within models, no therapy produced a signal in PBBI. Levetiracetam, which produced the highest overall score, produced its strongest signal in FPI, however, no other therapy in FPI reached threshold. In contrast, levetiracetam, glibenclamide, nicotinamide, and Kollidon VA‐64 all met/exceeded threshold in CCI (in that order). Eliminating negative points did not impact scoring for levetiracetam; it generated no negative points across models. However, glibenclamide, nicotinamide, Kollidon VA64, minocycline, and simvastatin all reach threshold (in that order). Eliminating negative points, levetiracetam and glibenclamide remained the highest scoring therapies; both generated ≥2X the points of any other therapy. Glibenclamide showed maximal efficacy in CCI. We conclude, levitiracetam and glibenclamide merit additional pre‐clinical/clinical study, with model dependence for glibenclamide. Eliminating negative points minimally impacted our conclusions. Alternative therapeutic approaches should also be explored across OBTT, particularly in PBBI (i.e., targeting regeneration, cell‐based therapies, or combination therapy). Support: DAMD W81HWH‐14‐2‐0118; W81XWH‐10‐1‐0623
Keywords: Consortium, Biomarker, Drug Screening, Translation
MILD TBI RESULTS IN HIPPOCAMPAL AND CORTICAL OSCILLATORY CHANGES THAT RESOLVE OVER TIME
University of California‐Davis, Neurological Surgery, Davis, USA
Despite the high prevalence of mild to moderate traumatic brain injury (TBI), little is known about the factors that play a role in recovery and the potential development of chronic cognitive deficits. We hypothesized that TBI would alter low frequency theta oscillations, corresponding with spatial learning deficits. Following lateral sham injury (n = 13) or lateral fluid percussion (n = 37) in rats, we analyzed electroencephalography (EEG) in the local field potentials from depth electrodes implanted in the hippocampus (HIPP) and anterior cingulate (ACC) in the first two weeks of recovery. All animals received a craniotomy over the right hippocampus, through which TBI rats received an injury (average 2.12 ATM), after which linear arrays of recording electrodes were implanted in both HIPP and ACC. TBI animals had significantly increased righting times (p < 0.001) and significantly greater weight decrease (p < 0.0001) compared to sham. Injured animals did not exhibit elevated latency on the Barnes maze (PID8‐11), although they did exhibit a greater percentage of random searches (p < 0.05), suggesting a mild injury. EEG from both ACC and HIPP collected on post‐injury days (PID) 3 and 7 indicated oscillatory aberrations that resolve over ∼10 days. TBI animals had decreased theta power (p < 0.0001), percent time in theta (p < 0.001), and a change in theta‐delta ratio (p < 0.01) in the HIPP compared to sham on PID3 but not PID7. Analysis of the ACC revealed significantly increased theta power (p < 0.001) on PID 3 and 7 with a decrease in peak frequency (p < 0.01) and significantly decreased theta‐delta ratio (p < 0.05) on PID3. Theta coherence between the HIPP and ACC was decreased on PID3 but resolved over time. These changes correspond with the timeline of neurochemical changes following TBI, such as abnormal calcium accumulation and alterations in glucose metabolism. These data highlight the therognostic potential of EEG analysis to noninvasively diagnose or track recovery following even a more mild TBI.
Keywords: Translational, Stereo/Intracranial EEG, Learning and Memory, Lateral fluid percussion
MACROPHAGE INFLAMMATORY PROTEIN‐1ALPHA (CCL3) AND ITS RECEPTORS CONTRIBUTE TO SECONDARY DAMAGE FOLLOWING SPINAL CORD INJURY
Medical College of Wisconsin, Neurosurgery, Milwaukee, USA
Secondary damage after spinal cord injury (SCI) occurs due to a sequence of events after the primary injury, contributing to increased lesion size and poor locomotor recovery. Thus, understanding secondary damage is critical to minimize tissue damage and improve neurological outcome. We have identified the expression of CCL3, a member of the CC chemokine family, and its receptors at different timepoints after SCI. We used adult female 6‐8 week old and were subjected to a moderate T11 contusion, and the expression levels of CCL3 and its receptors CCR1, CCR4 and CCR5 were characterized at the lesion site. CCL3 was upregulated after injury, with a peak at 6 hours and stayed upregulated for up to 28 days. Similarly, CCR1 and CCR5 expression was also increased at day 3 and 7‐post injury, respectively. CCR4 in contrast did not show any significant change (p < 0.05, n = 4‐5). Next, we compared locomotor recovery in CCL3 knockout and wild type mice. The Basso Mouse Scale locomotor score (BMS) showed that CCL3 knockout mice initially recovered better compared to wild type group, but at later time points, the scores started to decline, while the wild type group showed a slight improvement (p < 0.05, n = 9‐10). Then, we tried to identify the influence of CCL3 under inflammatory conditions in vitro using bone marrow derived macrophages (BMDM). When stimulated with LPS (1μg/ml), CCL3 knockout BMDMs showed significantly lower expression levels of M1 related factors TNF and IL12b compared to wild type. In addition, CCL3 deficient BMDMs had a higher baseline expression of the M2 related marker CD163 (p < 0.05, n = 4‐5), indicating a shift towards reduced pro‐inflammatory phenotype in the absence of CCL3. Collectively, we show that the proinflammatory chemokine CCL3 and its receptors CCR1 and CCR5 might be critically involved in the pathophysiology of inflammation and contribute to secondary damage following SCI, thereby providing a new potential target for SCI therapy.
Acknowledgement: Supported by Wings for Life 5088‐01.
Keywords: Microglia, Neuroprotection, Behavioral function, Gene expression
CEREBROVASCULAR REACTIVITY ASSESSED WITH FNIRS AND MRI AS A BIOMARKER OF TRAUMATIC CEREBROVASCULAR INJURY
University of Pennsylvania, Neurology, Philadelphia, USA
Chronic traumatic encephalopathy (CTE) is a neurodegenerative disease found most often in professional contact sport athletes (e.g. football players), military veterans, and others with a history of repetitive head impacts. Presently, CTE can only be diagnosed after death through neuropathological examination. The primary effects of repetitive mild traumatic brain injury (rmTBI) involve not only mechanical neuronal damage but also traumatic cerebral vascular injury (TCVI). TCVI is common after a single traumatic brain injury (TBI) and an attractive target for therapeutic intervention. We hypothesize that cerebro‐vascular reactivity (CVR) will be decreased in patients with TBI. Furthermore, we predict that 5‐week administration of a phosphodiesterase 5 (PDE5) inhibitor (sildenafil) will augment CVR in patients with a history of TBI. Hemodynamic changes were assessed using fNIRS, a noninvasive and portable neuroimaging modality that detects changes in blood oxygenation related to brain function. We assessed CVR by measuring the changes in oxygenated hemoglobin (ΔHbO) and deoxygenated hemoglobin (ΔHbR) concentration produced by mild hypercapnia (5% CO2) with complicated mild TBI (GCS 13‐15 with neuroimaging abnormality) in the acute (within 72hrs after injury, n = 17) and subacute (14 days after injury, n = 15) stages in addition to 11 age‐ matched healthy controls (HC), who were studied once. The change in CVR one hour after the administration of single dose of sildenafil citrate (60 mg orally) was also assessed. Mean (± SD) CVR was comparable in TBI patients and HC at 72 hours (HC:0.176 ± 0.028%/mmHg; and TBI:CVR 0.161 ± 0.011%/mmHg, p = 0.23). Sildenafil administration did not result in an increase in CVR in HC (t = 1.62 df = 8, p = .14) whereas sildenafil resulted in a significant increase in CVR at 72 hrs (t = 3.882 df = 16, p = .001) and 2 weeks (t = 2.5951 df = 13, p = 0.03) after TBI. We conclude that TCVI is common after mTBI, can be partially reversed by sildenafil administration. TCVI may be a mechanism for long‐term neurodegeneation after TBI, and play a role in the pathogenesis of CTE.
Keywords: Clinical Trial, CTE, Football, Vascular, Endophenotype
SERUM NFL SHOWS DIAGNOSTIC UTILITY AS A BIOMARKER IN CHRONIC TRAUMATIC BRAIN INJURY
1Henry M Jackson Foundation for the Advancement of Military Medicine, Bethesda, USA
2National Institutes of Health, Bethesda, USA
3Center for Neuroscience and Regenerative Medicine, Bethesda, USA
4Uniformed Services University of Health Sciences, Bethesda, USA
Keywords: NfL, tau, UCH‐L1, GFAp
CHANGES IN HIPPOCAMPAL SYNAPTIC PLASTICITY FOLLOWING EXPOSURE TO HIGH FREQUENCY HEAD IMPACTS (HF‐HI)
Georgetown University, Neuroscience, Washington, USA
Concussions account for over 70% of all cases of TBI reported each year. Sustaining multiple concussions is associated with the development of long lasting cognitive and memory impairments. The severity of these impairments increases in an injury frequency‐dependent manner. We sought to assess how injury frequency contributes to deficit development. Chronic traumatic encephalopathy (CTE) has been associated with the development of these impairments; however, it is unknown if the cognitive deficits associated with CTE can occur prior to the deposition of tau and death of neurons. We therefore also sought to identify any tau‐independent mechanisms associated with deficit development following exposure to multiple concussive impacts. To perform these studies, our group has developed a model of high frequency head impacts (HF‐HI) in which mice receive 5 hits a day for 6 days (30 hits total) that recapitulates the frequency of injuries experienced by athletes engaged in contact sports. Immunohistochemical analyses revealed that HF‐HI did not cause cell death, inflammation or excitatory synapse loss compared to sham mice. Despite the normal synapse number, behavioral testing at one‐month post injury showed that HF‐HI results in learning and memory deficits. We therefore hypothesized that HF‐HI was eliciting synaptic adaptations that alter physiological function. Whole cell patch clamp electrophysiology done on individual CA1 pyramidal neurons after HF‐HI reveal differences in intrinsic cellular properties, excitability, and NMDA receptor contributions to excitatory post synaptic currents after HF‐HI, showing that synaptic adaptations alter function following HF‐HI. Further, calcium imaging conducted concurrently with local field potential recordings reveals differences in calcium activity in HF‐HI mice. These changes had functional consequences, as hippocampal synaptic plasticity (examined using the long‐term potentiation (LTP) paradigm and extracellular field recordings) was impaired despite there being no difference in their stimulus input/output curve. We have concluded that exposure to a high frequency of concussive and sub concussive head impacts causes synaptic adaptations that alter plasticity, which potentially underlies the learning and memory deficits observed.
Keywords: Electrophysiology, Calcium Imaging, Concussion, Behavior
COMT AND ANKK1 GENETICS INFLUENCE IL‐6 LEVELS AND ASSOCIATIONS WITH DEPRESSION AND BEHAVIOR FOLLOWING TBI
1University of Pittsburgh, PM&R, Pittsburgh, USA
2University of Pittsburgh, School of Nursing, Pittsburgh, USA
3University of Pittsburgh, Safar Center, Pittsburgh, USA
4University of Pittsburgh, Clinical and Translational Science Institute, Pittsburgh, USA
Studies repeatedly show altered pro‐inflammatory interleukin‐6 (Il‐6) and anti‐inflammatory (Il‐10) levels post‐TBI. Our recent work has also evaluated how catechol‐o‐methyl transferase (COMT) Val158Met and ankyrin repeat and kinase domain containing 1 (ANKK1) Taq1a polymorphisms affect behavior in the context of depression. Given known relationships between sympathetic monoaminergic outflow on immunity, and regulatory effects of inflammation on dopamine neurotransmission, we investigated relationships between cytokine profiles and previously noted genetic differences in behavioral outcomes in the context of depression. Serum samples (n = 207) were drawn over a year and Il‐6 & Il‐10 levels were analyzed for (n = 121) adults with moderate‐to‐severe‐TBI. TaqMan allele discrimination technology was used for COMT genotyping. Depression status was collected using the self‐report Patient Health Questionnaire‐9 (PHQ9) and behavioral dysfunction with the Frontal Systems Behavioral Scale (FrSBe). COMT Met‐Homozygotes had higher Il‐6 levels at 0‐3‐months (p = 0.006) than Val‐carriers. Taq1a A2‐Homozygotes had higher Il‐6 levels at 0‐3‐months (p = 0.02) than A1 carriers. Depressed individuals at 12‐months also had higher Il‐6 levels at 0‐3‐months compared to non‐depressed individuals (p = 0.03). Depressed individuals who were A2‐Homozygotes had greater Il‐6 levels than all other subgroups. Higher Il‐10 levels were noted at 4‐6 & 7‐12‐months with COMT Met‐Homozygotes. Previously published relationships between depression, behavior, and genetics were confirmed. FrSBe scores were higher among depressed A2 homozygotes compared to A1‐carriers (p < 0.01), the same group that also showed the highest Il‐6 levels. This finding was not observed by COMT genotype. This is the first TBI study to describe differences in inflammatory markers based on genetic polymorphisms. Elevated Il‐10 at later time‐points post‐TBI for COMT Met‐homozygotes may represent a compensatory response to early elevated Il‐6 levels. Future work should investigate striatal impacts on DA‐inflammatory relationships with mood and behavior post‐TBI. Support: NIH‐R01‐HD048162 DOD‐W81XWH‐071‐0701, NIDILRR‐90DP0041.
Keywords: Genetic Factors, Inflammation, Biomarkers, Depression
DBB Data Blitz B: Mini Presentations
WHOLE BLOOD RESUSCITATION IMPROVES CEREBRAL PERFUSION AND OXYGENATION IN A RAT MODEL OF PENETRATING BRAIN INJURY AND HEMORRHAGE
1Walter Reed Army Institute of Research, Brain Trauma Neuroprotection Branch, Center for Military Psychiatry and Neuroscience, Silver Spring, USA
2University of Pittsburgh, Safar Center for Resuscitation Research, Pittsburgh, USA
3Uniformed Services University of the Health Sciences, Department of Surgery, Bethesda, USA
Pre‐hospital fluid resuscitation, using whole blood (WB) or lactated Ringer's (LR), remains the standard of care for hemorrhagic shock (HS). However, more robust resuscitation and higher mean arterial pressure (MAP) targets are required in the presence of concomitant TBI which can negatively affect outcome. The optimal resuscitation strategy for these patients is not yet defined.
To address this, rats were randomized into 4 groups (n = 10/group): LR with MAP target 60mmHg (LR60), LR with MAP target 70mmHg (LR70), WB with MAP target 60mmHg (WB60), WB with MAP target 70mmHg (WB70). All groups received a frontal penetrating ballistic‐like brain injury followed by a 35‐minute period of HS. During the pre‐hospital phase, rats received an initial bolus of resuscitation fluid followed by additional LR to maintain the MAP for 90 minutes. Physiological parameters were recorded continuously and cerebral edema was measured at 3 and 24 hrs post‐injury.
The WB60 (0.43 ± 0.24mL) and WB70 (8.73 ± 3.04mL) groups required significantly less LR during the pre‐hospital phase compared to LR60 (9.88 ± 2.11mL) and LR70 (21.08 ± 3.44mL), respectively (p < 0.01). A lower target MAP also reduced the required fluid volume for WB and LR (p < 0.05). WB60 and WB70 groups also demonstrated improved MAP, cerebral perfusion pressure, and brain tissue oxygen tension levels compared to LR. These improvements were observed at both MAP targets, indicating that a reduced target MAP did not compromise the physiological benefits. Despite the reduced fluid volume, no significant edema differences were observed.
WB resuscitation improved cerebral perfusion pressure, brain oxygen levels, and fluid requirements compared to LR. These improvements could be maintained following a reduced MAP target. Future studies targeting edema may be necessary.
Keywords: Whole Blood resuscitation, Penetrating Brain Injury, Hemorrhage, Cerebral blood flow, Brain tissue oxygen tension
REMOTE ISCHEMIC CONDITIONING PREVENTS TRAUMATIC BRAIN INJURY‐INDUCED ACUTE LUNG INJURY
1Arizona State Univeristy, Barrett Honors College, Tempe, USA
2University of Arizona COM‐PHX, Child Health, Phoenix, USA
3Phoenix Children's Hospital, Barrow Neurological Institute, Phoenx, USA
4University of Arizona COM‐PHX, Medicine, Phoenix, USA
5Phoenix VA Heath Care System, Phoenix, USA
Traumatic brain injury (TBI) causes central and peripheral inflammation, which increase organ susceptibility to injury. The lungs are particularly sensitive to peripheral inflammation, such that TBI can induce acute lung injury (ALI). Remote ischemic conditioning (RIC), repeated cessation and reperfusion of blood flow of a distal limb, has treated ALI, myocardial infarction, and neurological injury. We hypothesized RIC prevents TBI‐induced ALI through sphingosine‐1‐phosphate (S1P), a major regulator of lymphocyte and myokine trafficking. Male CD1 mice (n = 24) were subjected to either midline fluid percussion or sham injury and randomly assigned to 4 groups: sham noRIC, sham RIC, TBI noRIC, TBI RIC. RIC was performed on the proximal thigh for 4x5 minutes, with 5‐minute reperfusion one‐hour prior to TBI. One‐hour post‐injury, brain, lung, bronchoalveolar lavage (BAL) fluid, and blood were collected. Microglia and astrocyte activation were quantified in brainstem and cortex. Lung tissue was analyzed for alveoli damage. Pathology‐associated cell counts and neutrophils were quantified in BAL. Myokine and S1P expression were quantified in serum. One‐hour post‐injury, brainstem microglia had significantly shorter branch lengths in TBI noRIC compared to sham noRIC mice (F(1,20) = 5.46, p = 0.0300). All RIC mice had significantly shorter branch lengths compared to all noRIC mice (F(1,20) = 4.734, p = 0.0417). TBI damaged lung alveoli and increased neutrophil infiltration; RIC preserved alveoli and mobilized neutrophils. BAL from TBI noRIC mice had significantly more cells than sham noRIC (F(1,16) = 8.178, p = 0.0114) and cell numbers returned towards sham levels with RIC. In pooled samples, TBI elevated serum S1P by 13.5% compared to sham, and RIC reduced S1P by 37.7% compared to TBI noRIC. RIC exposed novel mechanisms of S1P signaling in TBI‐induced ALI. RIC therapy and future S1P pharmacology could prevent TBI‐induced ALI to preserve airways in clinical management.
Keywords: Acute lung injury, Midline fluid percussion injury, Remote ischemic conditioning
NEUROINFLAMMATORY AND SYNAPTIC CHANGES IN THE HIPPOCAMPUS FOLLOWING DIFFUSE BRAIN INJURY IN SWINE
1University of Pennsylvania, Neurosurgery, Philadelphia, USA
2Corporal Michael J Crescenz VAMC, Center for Neurotrauma, Neurodegeneration & Restoration, Philadelphia, USA
3Drexel University, School of Biomedical Engineering, Science, and Health Systems, Philadelphia, USA
4University of Pennsylvania, Bioengineering, School of Engineering and Applied Science, Philadelphia, USA
Each year in the United States, over 2.4 million people experience mild traumatic brain injury (mTBI), which can induce long term neurological deficits. The dentate gyrus of the hippocampus is notably susceptible to damage following TBI. Moreover, microglial activation after TBI may acutely alter hippocampal presynaptic inputs; however, the potential effects of chronic neuroinflammation are currently unknown. The objective of the current study was to assess neuropathological and neuroinflammatory changes in the dentate gyrus at acute to chronic timepoints following mTBI using an established model of closed‐head rotational acceleration induced TBI in swine. We detected non‐significant bimodal trends of microglia density changes in discrete hippocampal sub‐regions following mTBI; microglia density generally increased at 3 DPI, decreased at 7 DPI, and increased again at chronic timepoints. We observed a trending reduction in the number of microglia contacting hilar mossy cell somata in anterior hippocampus at 7 and 30 DPI. Furthermore, we found dramatic increases in synapsin staining around mossy cells at 7 DPI in both anterior (p = <0.0001) and posterior (p = < 0.0001) hippocampus, and also observed modest mossy cell hypertrophy at 30 DPI in both anterior (p = 0.0009) and posterior (p = < 0.0001) hippocampus. The alterations of mossy cell size and synaptic inputs paired with changes in microglia density around the cells demonstrate the vulnerability of hilar mossy cells after even mTBI. Moreover, this hilar mossy cell pathology may play a role in aberrant hippocampal function post‐TBI, potentially affecting dentate granule cells along the entire dorsoventral axis and thereby relatively enhancing perforant path inputs.
Keywords: large animal model, neuroinflammation, mTBI
SARM1 DELETION REDUCES AXON DEGENERATION, DEMYELINATION, AND WHITE MATTER ATROPHY AFTER EXPERIMENTAL TRAUMATIC BRAIN INJURY
1F. Edward Hebert School of Medicine, Uniformed Services University of the Health Sciences, Center for Neuroscience and Regenerative Medicine, Bethesda, USA
2USUHS, Biomedical Instrumentation Center, Bethesda, USA
3USUHS, Department of Microbiology and Immunology, Bethesda, USA
4USUHS, Department of Anatomy, Physiology and Genetics, Bethesda, USA
5USUHS, Program in Neuroscience, Bethesda, USA
Traumatic brain injury (TBI) often damages axons in white matter tracts and causes corpus callosum (CC) atrophy in chronic TBI patients. Injured axons encounter irreversible damage if transected, or alternatively may maintain continuity and subsequently either recover or degenerate. Secondary mechanisms can cause further axon damage, myelin pathology, and neuroinflammation. Molecular mechanisms regulating the progression of white matter pathology are important potential targets for developing therapeutics. SARM1 is essential for execution of the conserved axon death molecular pathway. We examined the contribution of SARM1 to axon degeneration and chronic white matter pathology by producing mild TBI with CC traumatic axonal injury in mice with genetic deletion of Sarm1 (knockout mice; Sarm1‐/‐). Ultrahigh resolution structural analysis at 3 days post‐TBI revealed dramatically reduced axon degeneration in Sarm1‐/‐ mice, as compared to wild‐type controls (C57BL/6 and Sarm1+/+). TBI induced demyelination, i.e. myelin loss along otherwise intact axons, was reduced in Sarm1‐/‐ mice, while redundant myelin figures remained elevated. We next assessed Sarm1 involvement in white matter neurodegeneration at 8 weeks post‐TBI in Sarm1‐/‐ mice crossed to Thy1‐YFP reporter mice. Cortical neurons under the impact site did not exhibit apoptosis or overt pathology, while occasional swellings in CC axons indicated continued axon damage. Importantly, TBI produced significant CC atrophy in Thy1‐YFP/Sarm1+/+ mice that was attenuated in Thy1‐YFP/Sarm1‐/‐ mice. Surprisingly, astrogliosis and microglial activation persisted in the CC of Thy1‐YFP/Sarm1‐/‐ mice. This study demonstrates that Sarm1 inactivation has promising acute and chronic benefits of reducing axon degeneration, demyelination, and white matter atrophy after TBI. Studies funded by the U.S. Department of Defense Center for Neuroscience and Regenerative Medicine (CNRM703386; CNRM702720) and Defense Health Agency (ST7434918).
Keywords: myelin, TAI, Sarm1, corpus callosum
TRAUMATIC BRAIN INJURY LEADS TO WIDESPREAD ACUTE AMYLOID‐BETA DEPOSITION IN THE ELDERLY
1University of Glasgow, Institute of Neuroscience and Psychology, Glasgow, UK
2University of Pennsylvania, Penn Center for Brain Injury and Repair and Department of Neurosurgery, Philadelphia, US
3Queen Elizabeth University Hospital, Neuropathology Research Laboratory, Glasgow, UK
Amyloid‐beta (A‐beta) plaques are recognised in up to 30% of patients dying acutely following a single moderate or severe traumatic brain injury (TBI). However, A‐beta plaque accumulation also occurs in a proportion of individuals with aging, and is a hallmark pathology of Alzheimer's disease (AD). There is, therefore, the potential that plaques documented after acute TBI in the older population might represent co‐existing pathology, rather than a TBI associated phenomenon. To address this, we examined A‐beta plaque and neurofibrillary tangle (NFT) pathology in aged TBI patients and matched non‐injured controls.
From the Glasgow TBI Archive, patients dying in the acute phase (< 2 weeks survival) following a single moderate or severe TBI and aged 60 years or older (n = 42) were identified, together with age‐matched controls with no known history of TBI or neurological disease (n = 42). Multiple brain regions were then stained for A‐beta and phosphorylated tau, and assessed for extent and distribution of pathologies using standardised, semi‐quantitative protocols.
There was no difference in prevalence of A‐beta plaque pathology or in extent and distribution of NFTs in aged acute TBI patients compared to controls. However, elderly TBI patients showed more widespread diffuse and fibrillary A‐beta plaque deposition, with 40% of acute TBI cases demonstrating plaque in three or more regions, compared to just 17% of uninjured elderly controls (p = 0.029).
These data suggest that an acute moderate or severe TBI in older patients is associated with more widespread A‐beta plaque deposition than might arise in context of normal aging. As such, this work reinforces the need for appropriate age‐matched controls when studying the pathology of survival from TBI, particularly in older individuals where ‘normal’ pathologies of aging might co‐exist.
Work supported by grants R01NS094003 & R01NS038104
Keywords: Amyloid‐Beta, Tau, Neurodegeneration
REDUCED COGNITIVE RESILIENCY OF ATTENTION‐DEFICIT/HYPERACTIVITY DISORDER AGAINST SUBCONCUSSIVE HEAD IMPACTS
Indiana University, Kinesiology, Bloomington, USA
Keywords: subconcussion, attention‐deficit/hyperactivity disorder, neurocognitive function, ImPACT, soccer heading, subconcussive head impacts
DEFICITS IN BEHAVIORAL FLEXIBILITY AND IMPULSE CONTROL ARE RESCUED WITH CUES FOLLOWING SEVERE FRONTAL BRAIN INJURY IN RATS
West Virginia University, Psychology, Morgantown, USA
Traumatic brain injury (TBI) often results in cognitive deficits associated with executive function. These often persist into the chronic post‐injury phase and may mediate the occurrence of other functional deficits (e.g. emotional dysregulation). In particular, long term deficits associated with impulse control and behavioral flexibility are common in humans. Due to the heterogeneity of clinical TBI and the resulting chronic dysfunction, it is beneficial to examine these deficits in animal models. The current research determined whether chronic deficits in behavioral flexibility and impulse control could be treated merely by environmental manipulations. Male Long Evans rats, separated into Sham (n = 42) and TBI (n = 37) groups, were used in these studies. TBI animals received a craniotomy and severe (5.0 mm diameter, 2.5 mm depth, 3 m/s) bilateral controlled cortical impact (CCI) to the frontal lobe (AP +3.0, ML +0.0 from bregma). Sham animals received an intact sham injury (no craniotomy). In experiment 1, attentional set shifting (AST), followed by probabilistic reversal learning (PbR), was used to examine deficits in behavioral flexibility. In experiment 2, differential reinforcement of low rate behavior (DRL) was used to measure impulse control. In half of the animals, an environmental intervention was introduced to rescue behavioral deficits, such that in PbR a cue light indicated higher probability of reinforcement, and in DRL, a cue light illuminated upon reinforcer availability. There were no group differences on the AST. However, flexibility was still impaired after injury as indicated by performance on the PbR. Impulsivity was also increased in TBI rats as indicated by poor DRL performance. Notably, the introduction of cues was able to significantly improve behavioral flexibility (to sham levels) and rescue impulsivity (to near‐sham levels). Establishing effective therapeutics for TBI related cognitive deficits is essential if we are to improve clinical outcomes. This research highlights the therapeutic effects of environmental manipulations and may help to direct the development rehabilitative strategies.
Keywords: TBI, Behavioral Flexibility, Impulse Control, Cue, Therapeutics
TIME INTERVAL TO EMERGENCE FROM COMA IN SEVERE TRAUMATIC BRAIN INJURY SURVIVORS WITH FAVORABLE OUTCOME AT 2 YEARS
University of Pittsburgh, Pittsburgh, USA
Keywords: TBI prognostics
PROBING THE OPERATION BRAIN TRAUMA THERAPY DATASET USING MACHINE LEARNING TECHNIQUES
1University of Miami, Neurological Surgery, Miami, USA
2University of Miami, Health Informatics, Miami, USA
3University of Miami, Computer Science, Miami, USA
4University of Miami, Psychology, Miami, USA
5University of Miami, Physical Medicine and Rehabilitaion, Miami, USA
Computational approaches fielded from machine learning (ML) have found successful applications in areas such as genomics and drug discovery and recent advances in these techniques have the potential to accomplish truly personalized medicine. However, challenges hindering their implementation into the neurotrauma field include its heterogeneous nature and the amount of quality data needed to build intelligent systems. To overcome these challenges, we utilized the experimental data obtained by Operation Brain Trauma Therapy (OBTT). Through a nationwide collaboration, OBTT is creating a dataset that spans multiple injury models and treatment strategies. For ML and personalized medicine, this presents the potential to develop an intelligent system able to capture variability between individuals, a feat which has eluded conventional analytics. Initially, we focused on one treatment, minocycline, administered following fluid percussion injury with the goal of identifying treatment effects undiscovered by the univariate‐driven scoring matrix utilized in OBTT. Through feature engineering, we curated a dataset that includes physiological, motor, and cognitive assessments. Two ML techniques were then applied to this dataset: (1) t‐SNE, a nonlinear, dimensionality reduction algorithm for visualizing high‐dimensional data and uncovering separability between treatments, and (2) k‐means clustering, an unsupervised learning technique with the purpose of identifying those groups. This revealed differences between TBI+Vehicle and TBI+Minocycline, a therapy that received zero points in the OBTT analysis. Visible clusters identified by k‐means represents a milestone; finding regularities within the data suggests ML techniques are a promising way to identify treatments influencing multivariate recovery. Ongoing work with the OBTT dataset aims to develop an intelligent system able to predict combinations of treatments with a high likelihood of synergy to add an informative component to the translational science workflow; from model to bench to bedside.
Keywords: machine learning, brain injury, functional recovery, prediction
DISSECTING THE ROLE OF CCL2 IN NEUROPATHIC PAIN DEVELOPMENT
Drexel University, Neurobiology & Anatomy, Philadelphia, USA
Neuropathic pain is recognized as a neuroimmune disorder; however, researchers have focused on either neuronal or immune mechanisms of pain, rarely examining both simultaneously. The lack of effective pain relief may be due to our limited understanding of the reciprocal relationship between neuronal dysfunction and the immune response to nerve injury in the development and maintenance of pain. We are particularly interested in the interaction between macrophages and primary nociceptive neurons found in the dorsal root ganglia (DRG). Previous data from our lab showed that spinal cord injury‐induced pain corresponds to a sustained macrophage presence in the DRG. Others have shown in models of neuropathic pain that reducing macrophage chemoattractant CCL2 signaling by knockdown of its receptor can prevent pain development. It is unclear whether CCL2 acts via macrophages to elicit pain behavior, or whether it acts directly on nociceptors, as CCL2 receptors are also found on neurons. To parse out whether elevated DRG CCL2 was essential to pain development in a macrophage‐dependent manner, we injected recombinant rat CCL2 or vehicle into the C7 and C8 DRG of uninjured adult, female Sprague Dawley rats and assessed neuropathic pain over time. As expected, rats that received CCL2 exhibited persistent forepaw hypersensitivity that did not resolve compared to naïve and vehicle‐treated rats (p < .05) as measured by von Frey and mechanical conflict avoidance paradigms. Rats were sacrificed at 5 and 20 days post injection, and RNA was isolated from C7 and C8 DRGs. qPCR analysis revealed that there was a 5 fold increase in CCL2, and concomitant increase in CD68, a macrophage marker. Surprisingly, the M2/anti‐inflammatory macrophage marker Arg1 was significantly elevated and the M1/proinflammatory macrophage marker iNOS was decreased compared to vehicle and naïve animals (p < .05). These data support the hypothesis that the chemoattractant CCL2 may be acting to reduce injury‐induced inflammation. Future studies will examine the influence of CCL2 and macrophages on nociceptor electrophysiological dysfunction as a mechanism of DRG neuroimmune interactions contributing to neuropathic pain. Support contributed by NIH R01 #097880
Keywords: Rat, CCL2, Dorsal Root Ganglion, Macrophage
CALIBRATED QUANTITATIVE MRI OF TBI ACROSS SPACE, VENDOR, SITE, AND TIME FOR DIFFUSION QUANTIFICATION OF DIFFUSE AXONAL INJURY DAI
1University Pittsburgh, Psychology, Pittsburgh, USA
2Psychology Software Tools, Pittsburgh, USA
3University Pittsburgh Medical Center, Neurosurgery, Pittsburgh, USA
4George E. Wahlen VAMC & Utah Univ., Salt Lake, USA
It has been a goal of MRI use in TBI to diagnosis tissue pathology based on stable normative data across MRI centers, instruments, and time, and to provide a comprehensive panel of each tract with quantitative norms by age. This goal is severely hindered by two factors. The first factor is the lack of calibrated metrics of axonal volume as a marker of diffuse axonal injury (DAI). DAI has been a defining metric of TBI since the studies of Strich (1956). The second factor is the high systematic between‐instrument error and also variability over time and brain space. The systematic error can be multiple times the TBI effect size (see Wilde et. al. 2018 Neurotrauma). This high error thwarts development of normative diagnostics classifications and artificial intelligence (AI) decision making. This presentation details potential solutions to both challenges. We introduce a new metric – Tract Axonal Volume (TAV) that provides a measure of axonal volume traveling along axons in a coherent direction quantified with MRI diffusion measurement of the directional axonal water per mm3 voxel in the tract. DAI increases as the percent of axons lost, and TAV decreases proportionally with high correlation in phantom tests. We can also detect, localize, and quantify white matter lesions (white matter hypo‐intensities). The phantom uses textile axonal shaped tubes that match histology established axonal size and packing density (0.8 micron tubes with a packing density of a million per mm2). The phantom calibrates TAV metrics across scanners, time, and space. Running a phantom scan on the scanner (at least quarterly) quantifies the scanner systematic error. We discuss the applicability of these measures in multi‐site studies and their ability to provide normative metrics for TBI diagnosis.
Keywords: Phantom, TBI, Measurement, Axonal Injury
TOWARDS PRECISION MEDICINE FOR THE INJURED BRAIN: AUTO‐TUNING OF CORTICAL SPREADING DEPOLARIZATION
Donald and Barbara Zucker School of Medicine at Hofstra/Northwell, Neurosurgery, Hempstead, USA
Keywords: spreading depolarization, trigeminal nerve stimulation, TBI, neuroprotection
WIDESPREAD AXONAL VOLTAGE‐GATED SODIUM CHANNEL CHANGES IN A SWINE MODEL OF CONCUSSION
University of Pennsylvania, Center for Brain Injury and Repair, Philadelphia, USA
Although concussion or mild traumatic brain injury (mTBI) is a major health concern, the underlying microscopic structural and pathophysiological changes are poorly understood. Nonetheless, emerging evidence suggests that selective damage to white matter axons and resulting axonal sodium channel abnormalities are important pathological substrates of mTBI. A small number of studies have shown that TBI induces voltage gated sodium channel (VGSC) dysfunction, which can trigger a feed‐forward mechanism of pathological sodium and calcium influx into axons, in turn, leading to axonal degeneration. Here, we examined isoform specific changes in VGSC expression and node of Ranvier (NOR) morphology using a clinically relevant concussion model of head rotational acceleration in swine. Notably, this model induces diffuse axonal injury (DAI) in the white matter with the identical appearance as found in human TBI. We observed an acute decrease of VGSC subtype, Nav1.6, in the white matter at 6 hours post injury, followed by a recovery observed at 72 hours and 2 weeks post injury. Additionally, atypical or disrupted NOR morphology was observed throughout the white matter, including in regions that did not display overt axonal damage identified as swollen axonal profiles. This included the loss of neurofascin‐186 immunohistochemical signal and bIV‐spectrin diffusion into paranodes. Finally, we also found increased numbers of void and amorphous nodes following injury. Consequently, these data demonstrate sodium channel changes and global NOR pathology beyond regions of axonal pathology in mTBI. These changes may play a role in the brain network dysfunction that underlies the clinical symptoms of mTBI. This work was supported by the Paul G. Allen Family Foundation, NIH Grants NS092398, NS038104, NS094003 and a PA CURE grant, 4100077083.
Keywords: Ion channel, node of ranvier, voltage‐gated sodium channels, spectrin
DATA SHARING IN TBI RESEARCH: OPEN DATA COMMONS FOR TRAUMATIC BRAIN INJURY (ODC‐TBI ALPHA)
1University of California San Francisco, Neurological Surgery, San Francisco, USA
2University of California San Francisco, Brain and Spinal Injury Center, San Francisco, USA
3University of California San Francisco, Physical Therapy and Rehabilitation Science, San Francisco, USA
4University of Texas Medical Branch, The Moody Project for Translational Traumatic Brain Injury Research, Department of Anesthesiology, Galveston, USA
5University of California San Diego, Department of Neuroscience, San Diego, USA
Traumatic brain injury (TBI) is a complex phenomenon involving molecular, cellular, anatomical, physiological and socio‐psychological changes. This complexity results in a large variety of variables and metrics across studies and laboratories, limiting reproducibility and bench to bed‐side translation. Data variety is one of classic “4V's of big‐data” (along with volume, velocity and veracity) that challenge traditional data science and statistical approaches. The challenge of TBI big‐data is aggravated by the current form of data dissemination that funnels research data (usually in the form of summary statistics) to a few pages in scientific publications and obscures source datasets in publicly‐inaccessible formats (‘dark data’) such as spreadsheets or paper records. Digital data‐sharing infrastructure can mitigate reproducibility problems and improve translation by promoting transparency in data dissemination with subject‐level data access that forms the materia prima for modern big‐data analytics. Here we present the early version of the Open Data Commons for TBI (ODC‐TBI;
NIH (NS088475, NS106899) and the US Department of Veterans Affairs (I01RX002245, I01RX002787).
Keywords: Traumatic brain injury, FAIR data, Data sharing, Open data commons
ASTROCYTE INJURY‐DEFINED (AID) BIOMARKER ASSAYS FOR PRECLINICAL NEUROTRAUMA MODELS AND DIAGNOSTIC MONITORING OF TBI PATIENTS
Victoria Parrilli1, Timothy Van Meter2, Nazanin Mirshahi2, Vanessa Cabra‐Hodge2, Joseph Green2, Gerry Shaw3, Rochelle Bitolas1, Kunal Ranat1, Melissa Walker4, Neil Harris4,
1UCLA, Semel Institute for Neuroscience and Human Behavior, Los Angeles, USA
2Brain Box Solutions Inc., Richmond, USA
3EnCor Biotechnologies Inc., Gainesville, USA
4UCLA, BIRC, Los Angeles, USA
Diagnosis, monitoring and outcome prediction are essential for translating novel TBI treatments from rodent to man. Our objective was to develop and validate immunoassays for quantitative assessment of novel Astrocyte Injury Defined, (AID) neurotrauma biomarkers useful for both animal models and TBI patients. AID biomarkers include Aldolase C (ALDOC), brain fatty acid binding protein 7 (FABP7) and small breakdown products of glial fibrillary acidic protein (sGFAP‐BDP, Halford et al., 2017). Species‐differences exist for biofluids and for biomarker protein sequences and kinetics. We established species‐specific cerebrospinal‐fluid (CSF) and serum preparations and validated both, assay standards and novel AID biomarkers antibodies. Serum albumin depletion was optimized using albumin‐binding magnetic beads for rat serum, and immunoaffinity columns for human serum, while retaining biomarkers in eluates. Custom‐antibodies to AID biomarkers were each validated separately for specificity and sensitivity using rat and human analytes, and recombinant proteins. Antibody specificity was determined using tissue lysates, dilution studies, recombinant biomarkers, isoforms and similar proteins using antigen‐antibody‐microarrays and western blotting. The best performing antibody pairs were then selected for mesoscale discovery platform (MSD) assay prototypes. Rodent AID biomarker detection was optimized by pre‐adsorbing antibodies with rat immunoglobulins before interrogation in immunoassays. The assays detected injury‐specific elevation of AID markers in CSF and serum after rat controlled cortical impact compared to sham. Pilot biomarker kinetic studies showed elevated ALDOC, GFAP and FABP7 at 1.5hrs post‐injury, while BDPs of ALDOC and GFAP accumulated by 24hrs post‐injury. These studies provide critical authentication of custom‐made antibodies for translational neurotrauma models and enable future clinical diagnosis and prognosis for TBI patients. Support: NIH 1UG3NS106945‐01, UG3‐TOP‐NT‐consortium (NGH, IBW), NINDS SBIR grant 1R43NS106972‐01 (TVM, IBW), BRAINBox Solutions, Inc.
Keywords: translation, serum, cerebrospinal fluid, controlled cortical impact, outcome, breakdown product
Poster Session Top Finalists
T01 Poster Session Finalists: Trainee Competition Finalists
RESPIRATORY TRAINING WITH INTERMITTENT HYPERCAPNIA TO ENHANCE PLASTICITY FOLLOWING CERVICAL SPINAL CORD INJURY
Drexel University College of Medicine, Neurbiology and Anatomy, Philadelphia, USA
Cervical spinal cord injury (SCI) frequently leads to severe respiratory dysfunction due to damage of the spinal phrenic motor system which controls the diaphragm ‐ the primary muscle for respiration. While some spontaneous functional plasticity does occur following cervical SCI, the extent is limited and diaphragm paresis persists. The goal of this ongoing research is to test whether a novel activity‐based therapy – daily acute intermittent exposures to hypercapnia – can enhance respiratory plasticity and diaphragm recovery after cervical SCI. We hypothesized that rehabilitation with this respiratory‐specific activity‐based therapy will stimulate anatomical and functional phrenic plasticity and improve diaphragm function following a moderate mid‐cervical contusion injury in the adult rat. Anatomical plasticity following injury and treatment was investigated using transynaptic tracing and immunohistochemistry. Pseudorabies virus (PRV) was used to retrogradely and transneuronally trace the spinal phrenic circuitry ipsilateral to injury and assess integration of premotor spinal interneurons with phrenic motoneurons. Immunohistochemistry and western blot analysis were performed to assess changes in serotonin (5‐HT) and BDNF expression, and axonal growth, rostral and caudal to injury. Functional plasticity and respiratory recovery following dAIHc training was assessed with terminal diaphragm electromyography (dEMG). Hypercapnia trained animals showed a greater density of serotonergic axons within the spinal cord, yet surprisingly an increased BDNF expression within the medulla, when compared with untreated and air control animals. It was also found that 2 weeks of dAIHc training resulted in a greater recruitment of interneurons into ipsilateral phrenic circuitry when compared to untreated and air controls. Diaphragm EMG of the dAIHc trained animals resulted in modest improvement of the ipsilateral and contralateral diaphragm inspiratory amplitude as well as response to respiratory challenge. These results therefore suggest that dAIHc is able to promote plasticity within the phrenic network following cervical SCI.
Keywords: Respiration, Respiratory Training, rehabilitation, plasticity
RESTING‐STATE FUNCTIONAL CONNECTIVITY IN U.S. VETERANS WITH SUBCONCUSSIVE BLAST EXPOSURE
1Duke University, Brain Imaging and Analysis Center, Durham, USA
2Durham VA Medical Center, Mid‐Atlantic MIRECC, Durham, USA
3Duke University, Department of Psychiatry and Behavioral Sciences, Durham, USA
Approximately 19%‐23% of Veterans deployed to Iraq and Afghanistan sustain a blast‐related traumatic brain injury (TBI), yet there are inconclusive results about the effects of subconcussive blast exposre on brain functional connectivity. The present study used a hypothesis‐generating approach to identify differences in resting‐state functional connectivity in Veterans who reported blast exposure but did not report acute clinical symptoms of mild TBI. Veterans (n = 169) were recruited through a mental health repository and screened for blast exposure using a retrospective structured interview. The sample was split into three groups for analysis: 1) controls without exposure to blasts (controls; n = 32), 2) subconcussive with exposure to blasts, but without TBI‐related symptoms (subconcussive; n = 70), and 3) mTBI with related symptoms immediately following blast exposure (mTBI; n = 67). Functional magnetic resonance imaging resting‐state scans were acquired and seed‐based connectivity analysis was performed using the CONN toolbox and Matlab. Age, sex, depression and post‐traumatic stress disorder (PTSD) were included as covariates. Differences emerged within the visual network between Veterans with blast exposure, regardless of symptom presentation, and unexposed controls. Specifically, the left lateral visual network (−37, −79, 10) showed decreased connectivity with bilateral putamen, bilateral insula, left planum polare, right central opercular cortex, and left pallidum in the mTBI and subconcussive groups when compared to controls. Findings were considered significant at a height‐threshold of p < 0.001 (at cluster‐level family‐wise error correction p < 0.01). Overall, blast exposure was related to functional hypoconnectivity in this the left lateral visual network, regardless of whether or not Veterans reported having acute clinical symptoms of mild TBI. These findings suggest blast exposure may alter the connections between visual perception and emotional processing. Additional research on the subconcussive effects of blast exposure is needed to further characterize this relationship.
Support: NINDS R01 NS086885. VA Mid‐Atlantic MIRECC.
Keywords: fMRI, Subconcussive, Blast, mTBI, Veterans, functional connectivity
TARGETING SARM1‐DEPENDENT AXONAL DEGENERATION PRESERVES NEURAL CONNECTIVITY AND IMPROVES FUNCTIONAL OUTCOMES AFTER TBI
Johns Hopkins University School of Medicine, Department of Pathology / Division of Neuropathology, Baltimore, USA
Traumatic axonal injury (TAI) is a common neuropathology in traumatic brain injury (TBI) and leads to disconnection as well as functional and cognitive/behavioral deficits. The majority of injured axons do not become transected by the biomechanical forces, but they undergo alterations and eventually succumb to fragmentation. The discovery that the enzyme SARM1 is an instructive signal in the execution of Wallerian degeneration in simpler models of injury raises the question of whether the same molecular mechanism is encountered in TAI and, if so, whether interventions to block SARM1 can protect injured axons and improve TBI outcomes.
Here we tested the role of SARM1 in TAI using the impact acceleration model and focusing on the corticospinal tract, a descending pathway responsible for skilled movements. We deleted SARM1 or pharmacologically inhibited the enzyme with the small‐molecule inhibitor FK866. We compared the number of spared axons post‐injury between wild‐type and SARM1 KO and also between vehicle and FK866‐treated mice and tested skilled motor function in the pellet‐reaching task. We found that SARM1 KO and FK866‐treated mice showed long‐term protection of corticospinal axons post‐injury. In addition, SARM1 KO and FK866‐treated mice showed preservation of their fine motor skills. Similar levels of protection in axonal degeneration and functional outcome were achieved with delayed treatment with FK866 up to 6 hours post‐injury.
Our findings indicate that SARM1 deletion or pharmacological inhibition preserve the structural and functional connectivity of the injured corticospinal tract and, by doing so, they preserve skilled motor function, pointing to the potential translational significance of this target in TBI.
Keywords: SARM1, FK866, Diffuse Axonal Injury, Axonal Degeneration
VOLUME OF SDH & EDH MEASURED BY COMPUTER‐ASSISTED ESTIMATION IS MORE PREDICTIVE OF MORTALITY AND FUNCTIONAL DISABILITY THAN ABC/2
1Warren Alpert Medical School of Brown University, Neurosurgery, Diagnostic Imaging, Emergency Medicine, Providence, USA
2Emory University School of Medicine, Emergency Medicine, Atlanta, GA
Keywords: Subdural Hematoma, Epidural Hematoma, Computer‐Aided Lesion Analysis, Outcomes Prediction
BENEFICIAL EFFECTS OF DELAYED POST INJURY TREATMENT WITH ANATABINE IN A MOUSE MODEL OF R‐MTBI
1Roskamp Institute, Sarasota, USA
2The Open University, Milton‐Keynes, UK
3James A Haley Veterans Administration, Tampa, USA
Mild TBI (mTBI) is the most common form of TBI and is referred as a “silent epidemic” due to the late manifestation of the injury outcomes. However, it is now recognized that the adverse effects, particularly of repetitive mTBI, continue for many years after the original event. More recently, attention has been given to the role of persistent inflammation in relation to the long‐term neurodegenerative consequences. Previously, we showed that chronic treatment with the drug Anatabine acutely after the injury improved cognitive functions and decreased inflammation. However, little is known about the benefits of the delayed administration of the same drug at chronic time points postinjury.
The purpose of the current study is to test the extent to which a delayed treatment can be beneficial after mTBI. We applied 24 mild impacts (midline, 5 m/sec, 1 mm depth, 200 msec) twice a week for 3 months in 3‐month‐old hTau mice (mice expressing 6 isoforms of human tau). We treated mice with Anatabine (20 mg/kg, in drinking water) or vehicle starting at 3 months post injury, then daily for 3 months. We examined the effect of Anatabine treatment on the functional and anatomical recovery from mTBI.
Our preliminary data showed that r‐mTBI caused motor impairment and a decrease in spatial learning compared to healthy controls. Moreover, r‐mTBI mice exhibited short‐term memory deficits as shown in the distance traveled and the time to locate the target box in the Barnes Maze test. Delayed treatment with Anatabine for 3 months returned both the motor performance and spatial learning back to the sham levels. Pathological analysis of the brain tissue for inflammatory markers and tau are ongoing. These data show that late administration of Anatabine has beneficial effects on r‐mTBI recovery in hTau mice and indicates the potential for late treatment to improve functional outcome.
Keywords: anatabine, tau, treatment, animal models
REVERSING INJURY‐INDUCED ENERGY DEFICITS PROMOTES CNS AXONAL REGENERATION AND FUNCTIONAL RECOVERY AFTER SPINAL CORD INJURIES
1Indiana University School of Medicine, Neurological Surgery, Indianapolis, USA
2National Institutes of Health, National Institute of Neurological Disorders and Stroke, Bethesda, USA
Axonal regeneration in the central nervous system (CNS) is a high energy demanding process. Extrinsic insults and intrinsic restriction lead to injured CNS axons in a state of local energy crisis, thus raising a fundamental question as to whether recovering energy deficit facilitates CNS regeneration following injury. Here, we reveal that enhancing axonal mitochondrial transport by deleting syntaphilin (snph), a gene encoding an anchor protein specific for axonal mitochondria, recovers injury‐induced mitochondrial depolarization. Using three different CNS injury mouse models, we demonstrate that snph‐/‐ mice display enhanced corticospinal tract (CST) regeneration passing through a spinal cord lesion, accelerated regrowth of monoaminergic axons across a complete spinal transection gap, and increased compensatory sprouting of uninjured CST. Notably, regenerating CST axons are able to form functional synapses, transmit electrophysiological signals, and promote motor functional recovery. Importantly, our energy crisis model is further supported by the finding that systemic administration of creatine, a bioenergetic compound, significantly facilitates CST regeneration. Thus, our study provides a new mechanistic insight into intrinsic regeneration failure in the CNS and suggests that enhancing local energy recovery is a promising strategy to promote axonal regeneration and functional recovery after CNS injuries.
Keywords: CNS Injury, Axon regeneration, Mitochondria, Energy
DIFFUSE TBI CAUSES MICROGLIA‐DEPENDENT NEURONAL DYSFUNCTION AND IMPAIRED AXONAL CONDUCTION
The Ohio State University, Neuroscience, Columbus, USA
Traumatic brain injury (TBI) elicits immediate neuroinflammatory events that cause acute cognitive, motor, and behavioral disturbances. Despite resolution of acute complications, functional impairments can develop after TBI. We previously identified microglia as mediators of inflammatory/immune signaling that persisted sub‐acutely following diffuse TBI in mice. It was unclear, however, if persistent microglial activation represented “reparative” adaptation or “neurodegenerative” maladaptation. Therefore, electrophysiological, histological, and transcriptome analyses were used to determine the contribution of microglia to neuropathology (with/without PLX5622‐mediated microglial depletion) at acute (1dpi), subacute (7dpi), and chronic (30dpi) time‐points. In these experiments, microglia were eliminated prior to midline fluid perfusion injury and axon conduction and cortical neuropathology/inflammation was assessed. There was a persistent reduction in N2/N1 amplitude of compound action potentials in the corpus callosum 30 dpi. This TBI‐associated impairment at 30 dpi was reversed by microglial elimination. To quantify cortical gene expression, Nanostring's Neuropathology gene expression assay (760 genes) was used. Novel data revealed robust increases in genes associated with inflammation and neuropathology acutely (1 dpi). Neuronal damage‐associated genes (Hmox1, Hsbp1, Fas) were microglia‐independent. At 7 and 30 dpi, however, microglial elimination reversed TBI‐related expression of genes associated with inflammation (Itgax, Cd14, Clec7a) and neuropathology (Serpinf1). Furthermore sub‐acute and chronic suppression of neuronal genes after injury were restored by microglial elimination (Ngf, Trpv1, Drd2, Avp). Moreover, when microglia were eliminated, TBI caused robust increase in genes related to angiogenesis. This suggests microglia prevent injury‐induced cortical angiogenesis. To understand how each cell type was influenced by injury and persistent microglial activation, we sequenced single‐cells. Analysis of cortical microglia 7 dpi revealed a unique neurodegenerative signature that was not present in uninjured controls or in microglia remaining following elimination. These injury‐associated microglia underwent transcriptional changes consistent with debris clearance and increased metabolism. Thus, microglia promote persistent neuropathological transcriptional and functional impairment after diffuse TBI.
Keywords: immune function, mTBI, electrophysiology, axonal injury
MICROGLIA DEPLETION AND REPOPULATION DURING THE CHRONIC STAGES OF TRAUMATIC BRAIN INJURY IMPROVES LONG‐TERM NEUROLOGICAL RECOVERY
UMB, STAR, Baltimore, USA
Microglial survival is dependent on the colony stimulating factor receptor 1 (CSFR1). CSFR1 inhibitors have been developed to investigate microglial function during physiological and pathophysiological conditions. Previously, we demonstrated that a delayed anti‐inflammatory treatment initiated at 1‐month following controlled cortical impact (CCI) improved long‐term neurological recovery in mice, in part by inhibiting NOX2‐dependent microglial activation. Using the CSFR1 inhibitor, PLX5562, we set out to test the hypothesis that removal of neurotoxic microglia during the chronic stages of TBI will improve neurological recovery and reduce chronic neurodegeneration. Adult male C57Bl/6 mice underwent sham or moderate‐level CCI. At 4 weeks post‐injury (WPI), mice were fed vehicle chow or PLX5622 (1200mg/kg) for 1‐week to deplete microglia, and were then returned to normal chow to allow microglial repopulation. Animals underwent a battery of motor and cognitive behavioral tests from 8‐12 WPI. At 12 WPI, mice were anesthetized, and brains were prepared for neuropathological assessments. A second cohort of animals were anesthetized at 8 WPI and brains were harvested for flow cytometry analysis. TBI + PLX5622‐treated mice had significant motor function improvements in a beamwalk task at 8, 10, and 12 WPI, when compared to TBI + Vehicle‐treated counterparts. In addition, TBI mice had significant cognitive impairments in the Y maze (10 WPI) and NOR (11 WPI) tasks when compared to sham‐operated mice; however, such impairment were not observed in TBI + PLX5622‐treated mice. In the MWM probe trial (12 WPI), TBI + PLX5622‐treated mice spent significantly more time in the target quadrant when compared to TBI + Vehicle‐treated mice. Notably, TBI + PLX5622‐treated mice had a significantly reduced cortical lesion volume and decreased NOX2+/CD68+ microglia. Furthermore, TBI + PLX5622‐treated mice had decreased microglial IL‐1b and caspase‐1 activity, when compared to TBI + Vehicle‐treated counterparts. Overall, our data demonstrates that depletion of microglia at 1‐month post‐injury results in long‐term improvements in neurological function associated with decreased TBI neuropathology.
Keywords: CSFR1, neuroprotection, cognition, neuropathology
DEEP BRAIN THETA STIMULATION RESULTS IN LASTING COGNITIVE IMPROVEMENTS FOLLOWING FLUID PERCUSSION INJURY
University of California Davis, Neurological Surgery, Davis, USA
Over 13 million people in the U.S. alone live with a TBI‐related disability and the majority of moderate and severe injuries result in chronic cognitive impairments. Deep brain stimulation (DBS) is an FDA‐approved therapy for multiple neurological diseases and is a modality currently being investigated for potential cognitive enhancement. Our lab has demonstrated that 7.7Hz theta frequency stimulation of the medial septal nucleus (MSN) improves learning following lateral fluid percussion injury (LFP). We now hypothesize that, 1) similar to pharmacology, there will be a therapeutic window for stimulation, and 2) that well‐timed stimulation will have lasting cognitive benefits. Sprague‐Dawley rats underwent either sham (n = 4) or LFP (n = 15). A bipolar tungsten electrode was implanted in the MSN approximately 30min post‐injury (PID0), and animals were divided into stimulation groups: NO stimulation, ACUTE (stimulation on PID0‐4), MID (PID3‐7), and LATE (PID8‐12). Stimulation occurred at 7.7Hz, 80uA, for 30min/day. Animals were tested on the Barnes maze (BM; PID8‐11), novel object recognition task (NOR; PID12), and Morris water maze (MWM; PID13‐17). Preliminary data indicates that, compared to sham, non‐stimulated LFP animals were impaired on the BM, NOR, and MWM. Animals in ACUTE and MID stimulation groups had improved performance on the first task, the BM, but not on NOR or MWM. Conversely, LATE stimulation impaired performance on BM but improved outcome in both later tasks, the NOR and MWM. Therefore, the data suggests that even acute stimulation had beneficial effects on cognitive outcome and that, regardless of timing, stimulation resulted in persistent but not indefinite benefits. Furthermore, 30min of stimulation immediately preceding BM impaired performance. Our data continue to support the potential of 7.7Hz stimulation of the MSN to improve cognitive outcome following TBI. These observations highlight the complexity of both disease and stimulation and why further experiments need to characterize the duration, intensity, and timing of stimulation necessary for persistent cognitive improvements without stimulation‐induced side‐effects.
Keywords: Theta Stimulation, Medial Septal Nucleus, Learning and Memory, Translational, Deep Brain Stimulation, Lateral Fluid Percussion Injury
ALTERED SEROTONIN SIGNALING AND ABERRANT SOCIAL BEHAVIORS STEMMING FROM BLAST‐INDUCED TRAUMATIC BRAIN INJURY
1University of Cincinnati, Pharmaceutical Science, Cincinnati, USA
2University of Cincinnati, Pharmacology and Systems Physiology, Cincinnati, USA
Traumatic brain injury (TBI) is estimated to cost the United States nearly $76 billion annually. A comorbidity of TBI is the generation of neuropsychiatric disorders including depression and aberrant social behaviors. Serotonin (5‐HT) is a monoaminergic neurotransmitter linked to the etiology of various neuropsychiatric disorders. We hypothesize that diffuse TBI alters CNS 5‐HT signaling, an effect that ultimately drives behavioral changes related to social withdrawal and despair. To test this hypothesis, murine subjects underwent a single, acute blast‐induced TBI or sham treatment. High performance liquid chromatography (HPLC) revealed increased 5‐HT and 5‐HIAA levels within the dorsal raphe nucleus (DRN) of TBI subjects compared to their sham counterparts 10 days post‐injury (dpi). Administration of the 5‐HT precursor, 5‐hydroxytryptophan (5‐HTP) resulted in a potentiation of head twitch response (HTR) in TBI subjects (10 dpi). Administration of the 5‐HT2A receptor agonist 1‐(2,5‐dimethoxy‐4‐iodophenyl)‐2‐aminopropane (DOI), revealed a potentiation of 5‐HT2A receptor sensitivity elicited by TBI (HTR, 3 and 10 dpi). No concomitant changes in 5‐HT1A receptor sensitivity were detected in TBI subjects following administration of the 5‐HT1A agonist (±)‐8‐Hydroxy‐2‐(dipropylamino)tetralin (8‐OH‐DPAT) (10 dpi). Radioligand binding assays using the 5‐HT2A specific ligand [3H] ketanserin revealed increased cortical receptor expression following TBI (3 and 10 dpi). Furthermore, decreased expression of the serotonin transporter was detected in the DRN following TBI (3 dpi). We hypothesized that changes in 5‐HT signaling act to alter sociability following injury. The Crawley Three Chamber Sociability Assay and the Tube Test for Social Dominance revealed significant deficits in sociability and social dominance, respectively, in TBI subjects (10 dpi) as compared to their sham counterparts. These studies suggest that TBI alters the homeostatic status of the 5‐HT signaling machinery of the CNS, effects that may drive TBI‐induced changes in behavior related to the generation of neuropsychiatric disorders.
Keywords: Serotonin, Blast Traumatic Brain Injury, Behavior
REVERSE TRANSLATIONAL APPROACH ON USING NEUROIMAGING AND BLOOD‐BASED PRECISION BIOMARKERS AS ENDPOINT ASSESSMENTS FOR TBI SUBPHENO
Tian Zhu1, Zhihui Yang1,4,
1Department of emergency medicine, College of Medicine, Unversity of Florida, Gainesville, USA
2Department of Anesthesiology College of Medicine, University of Florida, Gainesville, USA
3Department of Psychiatry University of Florida, Gainesville, USA
4Brain Rehabilitation Research Center Malcom Randall VA Medical Center, Gainesville, USA
Pathophysiological mechanism of traumatic brain injury (TBI) is heterogeneous including axonal injury, white matter integrity, microvascular injury and neuroinflammation. Here we used three diverse rat TBI models (fluid cortical impact(FPI), fluid percussion injury(CCI) and weight‐drop acceleration impact(WD)) to examine a panel of biofluid‐based biomarkers and MRI‐based neuroimaging sequences that can address clinically relevant TBI pathological subphenotypes. Serum biomarkers were assessed at 1‐2d, 7d and 4 weeks post‐injury, MRI imaging were conducted at day 2 and 4 weeks. Candidate biomarkers included phosphorylated neurofilament heavy (pNF‐H), neurofilament light (NF‐L), Tau for axonal injury, neuron specific enolase (NSE) and glial fibrillary acidic protein (GFAP) for contusion/ necrosis. In parallel, MRI scanning sequences were carried out at 11.1 Tesla (Bruker), at 7 Tesla (MR solution) and 4.7 Tesla (Aglient), as follows:T2*, T2, diffusion‐weighted imaging (DWI) and susceptibility weighted imaging (SWI). All three TBI models showed a different temporal serum Tau profile – peaking at day 1 in CCI, while peaking at day 7‐30 in FPI and WD. Serum GFAP signals peak at d1 across models. Serum pNF‐H signals are much higher in FPI models (median 280 pg/mL) in FPI at d1 compared to the CCI counterpart (median 50 pg/mL). For MR neuroimaging, the fractional anisotropy (FA) maps illustrate a lower FA for whiter matter (WM) relative to naïve controls at d2 and this change persists to a lesser extent by d30. In contrast, mean diffusivity (MD) is high in WM at d2 and remains high in the lesion site. Our data suggest the feasibility of using blood‐based temporal biomarkers and MRI neuroimaging biomarkers in assessing TBI subphenotypes in several rat models.
Keywords: Biomarker, Imaging, Axonal injury, White matter
RAPID ASTROCYTE ACTIVATION FOLLOWING JUVENILE TBI IS AN IMPORTANT SOURCE OF INFLAMMATORY MEDIATORS
University of Iowa, Pediatrics, Iowa City, USA
Compared to microglia, astrocyte activation has been reported to occur in a more delayed fashion following brain trauma. Past studies have focused on the reparative processes driven by astrocyte activation such as glial scar formation and its role in limiting secondary injury. Recently, the duality of neurotoxic (A1) vs. neuroprotective (A2) astrocyte activation has been recognized; neurotoxic astrocyte gene signatures were identified and demonstrated to contribute to secondary neuronal injury following neurologic insult. Characterization of astrocyte phenotype (pan‐reactive, A1, A2) following pediatric TBI and its impact on inflammatory mediator production have not been previously reported and are important in understanding the glial specific contributions to neuroinflammation. We used lateral fluid percussion injury adapted to PND 18‐24 C57BL/6J mice to model moderate‐severe pediatric TBI. Tissue expression of cytokines and astrocyte activation markers was evaluated by qPCR. Additionally, glial populations were isolated by FACS sorting, and glial‐specific gene expression was evaluated by qPCR. At 24 hours, pediatric FPI resulted in increased inflammatory cytokine expression (IL‐1β, TNF, and IL‐6) in both focal (ipsilateral parietal cortex, hippocampus) and remote regions (brainstem). Pediatric FPI also resulted in astrocyte activation 24hrs post‐injury: pan‐reactive astrocyte markers (Lcn2, GFAP, Vimentin), A1 markers (Serping1, C3), and A2 markers (S100a10, Ptx3, Stat3) were increased at the tissue level in ipsilateral hippocampus. Glial‐specific gene expression revealed increased inflammatory cytokine expression (IL‐1β, TNF, IL‐6, Ccl2) in FACS sorted astrocytes 24 hours post‐juvenile FPI. Conclusions: Juvenile FPI results in rapid astrocyte activation which contributes importantly to increased inflammatory cytokine expression. Key differences between microglia and astrocytes in inflammatory cytokine expression were noted 24 hours post‐injury. Ongoing studies will compare the relative contribution of astrocytes and microglia to inflammatory mediator production and elucidate how astrocyte activation changes over time.
Acknowledgements: K12HD27748, K08NS110829
Keywords: TBI, Astrocyte, Inflammation, pediatric
ACTIVATION OF MITOCHONDRIAL BIOGENESIS AS A THERAPEUTIC APPROACH FOR THE TREATMENT OF TRAUMATIC BRAIN INJURY
1University of Kentucky, Spinal Cord and Brain Injury Research Center, Lexington, USA
2University of Kentucky, Department of Neuroscience, Lexington, USA
3University of Arizona, Department of Pharmacology and Toxicology, Tucson, USA
4Lexington VA Health Care System, Lexington, USA
Mitochondria play a pivotal role in mediating secondary injury events following traumatic brain injury (TBI) and protecting the mitochondrial function improves neuronal function post‐TBI. Mitochondria are dynamic organelles continuously undergoing fusion and fission and their levels are regulated by the process of mitochondrial biogenesis (MB) and mitophagy. Activation of MB may be an important intervention to restore mitochondrial and brain function. We used formoterol, a highly selective β2‐adrenergic receptor agonist, to induce MB and determine whether it protected against secondary damage after severe controlled cortical impact (CCI) in 7‐9 week old C57BL/6 male mice. The TBI‐injured mice were injected (i.p.) either with vehicle (normal saline) or formoterol (0.3mg/kg) at 15 min, 8h, 16h, 24h post‐injury and subsequently every day until euthanasia. Ipsilateral hippocampus and cortex, directly under the impact, were used to assess mitochondrial copy number and/or bioenergetics function at 48h post‐injury. Post‐TBI, both cortex and hippocampal mitochondrial respiration rate, as assessed by oxygen consumption rate (OCR), and cortical mitochondrial DNA copy number were significantly improved with formoterol administration compared to CCI‐vehicle group. Novel object recognition (NOR) and Morris water maze (MWM) were performed in a separate cohort of mice on days 3‐4 and days 12‐15 post‐CCI, respectively. The results revealed a significant improvement in these cognitive tasks in CCI‐formoterol group compared to CCI‐vehicle group. Collectively, these results indicate that MB may be a key regulator of mitochondrial bioenergetics restoration and promote functional recovery post‐TBI.
Keywords: mitochondria, bioenergetics, mitochondrial biogenesis, traumatic brain injury
THE VOLTAGE‐GATED PROTON CHANNEL HV1 IMPAIRS RECOVERY AFTER TRAUMATIC BRAIN INJURY THROUGH ALTERED MICROGLIA/MACROPHAGE RESPONDS
1University of Maryland School of Medicine, Department of Anesthesiology & STAR, Baltimore, USA
2Mayo Clinic, Department of Neurology, Rochester, USA
The voltage‐gated proton channel Hv1 can rapidly remove protons from depolarized cytoplasm and is highly expressed in the immune system. In the mouse brain, Hv1 is expressed by microglia but not neurons or astrocytes. Microglial Hv1 regulates intracellular pH and aids in NADPH (NOX)‐dependent generation of reactive oxygen species (ROS). However, neither the cellular mechanisms nor critical role of Hv1 in the pathophysiology of traumatic brain injury ((TBI) are fully understood. In the present study, we report a rapid and persistent up‐regulation (12 folds at 7‐day and 4 folds up to 1 month) of Hv1 mRNA in the injured cortex after a moderate controlled cortical impact (CCI) in male mice. Western blot showed that CCI induces 3‐4‐folds elevation of Hv1 protein expression at 7 days post‐injury and sustained up to 1‐month post‐injury. qPCR, flow cytometry, and IHC analysis showed that depletion of Hv1 in KO mice significantly attenuates NOX2/ROS production and pro‐inflammatory cytokines, however, promotes a battery of anti‐inflammatory cytokines. Assessment of fine motor coordination using a beam walk test demonstrated better motor performance in Hv1 KO/TBI vs WT/TBI mice. In a battery of neurobehavioral tests, WT/TBI mice displayed significant cognitive deficits as demonstrated by reduced % spontaneous alternation in Y maze test, reduced time with novel object in Novel Object Recognition test, and reduced time in platform quadrant in Morris Water Maze test. In contrast, Hv1 KO/TBI mice did not display significant deficits in any cognitive test, indicating improved learning and memory performance. Furthermore, the functional improvement in Hv1 KO/TBI mice was associated with decreased cortical lesion volume and reduced infiltration of F4/80 macrophages. Taken together, our data indicate an important role for Hv1 in regulating NOX2/ROS‐mediated functional damage post‐TBI.
Keywords: Voltage‐gated proton channel Hv1, Traumatic brain injury, Microglia/macrophage, Neuroinflammation, Functional outcome
SEXUAL DIVERGENT RESPONSES OF NEUROINFLAMMATION AND FUNCTIONAL RECOVERY TO SPINAL CORD INJURY
University of Maryland School of Medicine, Department of Anesthesiology & Center for Shock, Trauma and Anesthesiology Research (STAR), Baltimore, USA
Spinal cord injury (SCI) causes not only sensorimotor deficits, neuropathic pain, and autonomic dysfunction but also varying degrees of neuropsychological abnormalities. Epidemiological studies report males have a higher likelihood of getting a SCI than females, however, little is known about the effect of biological sex on brain dysfunction and injury mechanisms. In the present study, young adult male and female C57BL/6 mice were subjected to moderate/severe contusion SCI and their functional outcomes were evaluated using neurobehavioral tests including motor function [Basso Mouse Scale (BMS), open field (OP), CatWalk], cognition [Y‐maze, novel object recognition (NOR)], depression [tail suspension (TS), forced swim (FS), and novelty‐suppressed feeding (NSF)], and cutaneous hypersensitivity at hind‐paws (von frey and thermal stimulation). Female mice were generally more active, as evidenced by greater distance traveled in the OP and higher numbers of total arm entries in the Y‐maze. After SCI, female mice had better BMS and motor coordination than those in male animals. SCI caused poor performance in male mice compared to female in the NOR and Y‐maze tasks as well as NSF test indicating impairment of cognition and depressive‐like behavior. However, no statistically significant differences were found between two sexes in mechanical/thermal stimulation at the hind‐paws. These functional impairments were associated with reduced spared white matter and neuronal survival in SCI/male mice. Using NanoString technology, about 800 neuroinflammatory genes were analyzed in injured spinal cord and cerebral cortex. Three days after SCI, female mice showed more aggressive neuroinflammatory profile than that in SCI/male animals. However, at 8 months after SCI, female mice revealed less neuroinflammation compared with male animals. Collectively, these findings indicate that sexual differences on functional outcome after SCI are associated with disrupted neuroinflammation not only in injured site but also in remote brain region. Thus, biological sex should be considered when designing new therapeutic agents.
Keywords: Male Female sex difference, Motor function, Brain dysfunction, Neuroinflammation
A NEW UNDERSTANDING OF THE PHENOTYPE AND DISTRIBUTION OF TAU PATHOLOGY IN CHRONIC TRAUMATIC ENCEPHALOPATHY
1University of Pennsylvania, Neurosurgery, Philadelphia, USA
2University of Pennsylvania, Center for Neurodegenerative Disease Research, Philadelphia, USA
3University of Glasgow, Neuropathology, Glasgow, UK
Traumatic brain injury (TBI) is a risk factor for neurodegenerative disease, in particular chronic traumatic encephalopathy (CTE). Current consensus criteria define the pathognomonic lesion of CTE as patchy tau pathology within neurons and astrocytes at the depths of cortical sulci. However, it remains unknown which aspect of this pathology might be unique to CTE. Here we performed comprehensive tau distribution mapping and phenotyping of CTE and compared to Alzheimer's disease (AD), primary age‐related tauopathy (PART), primary tauopathies, and aging‐related tau astrogliopathy (ARTAG). From the Glasgow TBI Archive and Penn Neurodegenerative Disease Brain Bank, cases were selected as: athletes with a history of repetitive mild TBI (n = 12) and long‐term survivors of severe TBI (n = 4) with CTE pathology; uninjured controls with ARTAG (n = 5); PART (n = 2); AD (n = 6); and primary tauopathies (n = 3). Representative sections were stained for tau and maps of neuronal and astroglial pathologies generated to examine their respective cortical distributions. Further, tau phenotypes were determined using antibodies specific for phosphoepitopes (PHF1, CP13, AT100, pS262), microtubule‐binding repeat domains (3R, 4R), truncation (Tau‐C3) and AD‐conformation (GT‐7, GT‐38). Comprehensive cell mapping revealed that astrocytes, but not neurofibrillary tangles (NTFs), preferentially concentrate at depths of sulci. Furthermore, TBI‐associated astroglial pathology was comprised of 4R tau thorn‐shaped astrocytes, identical in both morphology and immunophenotype to ARTAG. In contrast, NFTs contained both 3R and 4R tau, with post‐translational modifications and conformations consistent with AD and PART. Here we show that astroglial tau pathologies in CTE are phenotypically and conformationally distinct from adjacent NFTs. Moreover, astrocytes, but not NFTs, underlie the proposed pathognomonic sulcal depth predominant pathology of CTE. These findings underscore the need for continued interrogation and refinement of our understanding of the pathology of CTE. Funding: NIH Grants R01NS094003, R01NS038104, TL1TR001880.
Keywords: Chronic traumatic encephalopathy, Neuropathology, Neurodegeneration, Tau
EXTRACELLULAR VESICLES AS DIAGNOSTIC AND PROGNOSTIC BIOMARKERS OF TRAUMATIC BRAIN INJURY
University of Pennsylvania, Philadelphia, USA
Keywords: Extracellular vesicles
PREDICTING CONCUSSION OUTCOME USING FINITE ELEMENT MODELING AND NETWORK ANALYSIS
1University of Pennsylvania, Bioengineering, Philadelphia, USA
2University of Virginia, Center for Applied Biomechanics, Charlottesville, USA
Concussion is a significant public health problem affecting 1.6 to 2.4 million Americans annually. Despite this prevalence, there has not yet been a successful clinical trial to treat concussion. An alternative to reducing the burden of concussion is to reduce its incidence with improved helmets designs. Finite element models (FEMs) of the brain response to blunt trauma are often used to estimate injury potential, but these models currently do not take into account how the patterns of connectivity disruption affects the relay of information in the injured brain, nor do they consider differences in individual brain architectures and their purported role in concussion risk. Graph theory presents a way to describe these network‐based differences. Here, we use graph theory techniques to integrate brain deformations from finite element modeling with measurements of network efficiency to identify brain regions whose connectivity characteristics may influence concussion risk. Importantly, we found that brain regions that deformed the most during an impact did not overlap with regions most important for network function. Specifically, we found that high strains concentrated near the central sulcus, superior temporal gyrus, and pars opercularis, while network important regions primarily concentrated in subcortical structures and the posterior cingulate. However, we observed that using an increasing number of “network important” regions was far more effective in accurately predicting concussive injury than “strain important” using logistic regression techniques. These results suggest a more precise approach to estimating concussion risk and, in turn, develop more effective helmets to reduce concussion incidence.
Keywords: Concussion, Networks, Graph Theory, Finite Element Modeling
LYMPHOCYTE AND BDNF ASSOCIATIONS WITH RISK FOR PERSISTENT HYPOGONADOTROPIC HYPOGONADISM
1University of Pittsburgh, Department of PM&R, Pittsburgh, USA
2University of Pittsburgh, Department of Emergency Medicine, Pittsburgh, USA
3University of Pittsburgh, Safar Center for Resuscitation Research, Pittsburgh, USA
4Mount Sinai Icahn School of Medicine, Department of Rehabilitation Medicine, New York, USA
5University of Pittsburgh, Clinical and Translational Science Institute, Pittsburgh, USA
Persistent hypogonadotropic hypogonadism (PHH) is common after traumatic brain injury (TBI) and our previous work suggests that testosterone deficits associated with PHH are evident by 3‐months post‐injury and persist for the first‐year post‐injury. Further, our work shows that PHH contributes to poor outcomes post‐TBI. Also, BDNF expressing lymphocytes have been linked to neurodegenerative disease risk and also stroke recovery. Moreover, systemic BDNF levels are thought to reflect brain levels of BDNF, and multiple elements of hypothalamic function are modulated by BDNF. Thus, we used PHH as a secondary condition exemplar to demonstrate lymphocyte associations with serum BDNF levels among adult men (n = 143) with moderate‐to‐severe TBI. Individual regression models (linear/logistic) delineated individual relationships supporting our conceptual framework. We observed relationships between these markers and PHH status. Serum testosterone and luteinizing‐hormone levels were used to adjudicate PHH status. Average serum BDNF levels, was measured 2‐weeks to 6‐months post‐injury (n = 112 samples). Lowest daily lymphocyte counts were averaged from 0‐20‐days post‐injury and suggest lymphocyte reductions compared to reference levels. Linear regression, adjusted for age and Glasgow Coma Scale, showed an age‐lymphocyte interaction that was significant for BDNF (β = 4.84, p = 0.0012). Furthermore, covariate adjusted logistic regression showed that BDNF (OR = 0.992, p = 0.02) levels significantly predicted PHH status. These data describe a novel pathway to PHH through reductions in BDNF, which may be initiated by early reductions in circulating lymphocytes post‐TBI. Since BDNF is a manipulatable biological target, the link between BDNF and PHH status indicates the potential for intervention. Observed interactions suggest increased age‐related vulnerability to PHH. Further work should explore aging mechanisms post‐injury for other long‐term outcomes.
Support: UPP‐Foundation, NIDILRR‐90DP0041, DODW81XWH‐071‐0701.
Keywords: Biomarker, Endocrine Dysfunction, Aging
AIRYSYNAPSE—A NOVEL SUPER‐RESOLUTION IMAGING TECHNIQUE TO STUDY IMMUNE‐MEDIATED TRAUMATIC SYNAPTIC INJURY
Washington University School of Medicine, Neurology, St. Louis, USA
The complex microconnectivity of the mammalian brain underlies its computational abilities, and its unique vulnerability to injury. It has been challenging, however, to illuminate the features and dynamics of this synaptic network due in part to the small size and exceptionally dense packing of its elements. To better understand pathways leading to neural circuit damage after traumatic brain injury (TBI) we developed and implemented
Keywords: Gray matter injury
Poster Session Monday
A01 Aging
AGED RATS HAVE AN ALTERED IMMUNE RESPONSE AND WORSE OUTCOMES AFTER TRAUMATIC BRAIN INJURY
1Monash University, Department of Neuroscience, Melbourne, Australia
2The University of Melbourne, Department of Medicine, Melbourne, Australia
3La Trobe University, Department of Physiology, Anatomy and Microbiology, Melbourne, Australia
4University of Calgary, Department of Psychology, Calgary, Canada
Initial studies suggest that increased age is associated with worse outcomes after traumatic brain injury (TBI), though the pathophysiological mechanisms responsible for this remain unclear. Immunosenescence (i.e., dysregulation of the immune system due to aging) may play a significant role in influencing TBI outcomes. This study therefore examined neurological outcomes and immune response in young‐adult (i.e., 10 weeks old) compared to middle‐aged (i.e., 1 year old) rats following a TBI (i.e., fluid percussion) or sham‐injury. Rats were euthanized at either 24 h or one‐week post‐injury to analyze immune cell populations in the brain and periphery via flow cytometry, as well as telomere length (i.e., a biomarker of neurological health). Behavioral testing, as well as volumetric and diffusion‐weighted MRI, were also performed in the one‐week recovery rats to assess for functional deficits and brain damage. Middle‐aged rats had worse sensorimotor deficits and shorter telomeres after TBI compared to young rats. Both aging and TBI resulted in worse cognitive function and reduced cortical volume. These changes occurred in the presence of fewer total leukocytes, fewer infiltrating myeloid cells, and fewer microglia in the brains of middle‐aged TBI rats compared to young rats. These findings indicate that middle‐aged rats have worse functional deficits, decreased cortical volume, and shorter telomeres after TBI than young rats, and this may be related to an altered neuroimmune response. Although further studies are required, these findings have important implications for understanding the pathophysiology and optimal treatment strategies in TBI patients across the life span.
Keywords: neuroinflammation, aging, immunosenescence, immunology, MRI, DTI
PROGNOSTIC FACTORS OF INTENSIVE TREATMENT FOR GERIATRIC TBI: ANALYSIS OF 1,879 CASES FROM JAPAN NEUROTRAUMA DATA BANK
1Nippon Medical School, Department of Emergency and Critical Care Medicine, Tokyo, Japan
2Yamaguchi University, Department of Neurosurgery, Ube, Japan
3The Japan Neurotrauma Data Bank Committee, The Japan Society of Neurotraumatology, Tokyo, Japan
With the increase of the elderly population, there has been an abrupt increase of elderly traumatic brain injury (TBI) patients in Japan. However, there had been less data on the effectiveness of aggressive treatment and their prognosis in geriatric TBI. The aim of this study was thus to analyze the prognostic factors of aggressive treatments in geriatric TBI with the data of Japan Neurotrauma Data Bank Projects. Of 4,527 cases registered in the four JNTDB projects (from 1998 to 2015), 1,879 geriatric TBI cases (≥65) were analyzed. The clinical features, the percentage of aggressive treatment defined as surgical procedure and/or intensive temperature treatment including ICP monitoring, and outcomes based on Glasgow Outcome Scale were compared among four study projects. To clarify the prognostic factors in aggressively treated geriatric TBI patients, logistic regression analysis was performed. The percentage of geriatric TBI population was significantly increased throughout projects. (P1998; 30.1%, P2015 53.6% p < 0.0001). Aggressive treatments including surgical management and targeted temperature management (TTM) were performed in 69.3% in P2015 and this percentage was significantly increased. Less invasive treatments, like as trephination and TTM, tend to be chosen for geriatric patients. Mortality was significantly decreased (P1998; 62.8%, P2015; 44.7%, <0.0001), however the percentage of severe disability was significantly increased. Intraventricular hemorrhage was the strongest unfavorable prognostic factor (OR 3.99, 95% CI 2.05 – 7.76, < 0.0001). Conclusively, our efforts with the aggressive, less invasive treatments provided less mortality in geriatric TBI patients. However, these efforts did not result in better functional outcome in this population. Multimodal specific treatment strategy, like as rehabilitation and regenerative therapy, should be established.
Keywords: Traumatic brain injury, Elderly, Intensive care, Prognosis
CHIMERA REPETITIVE MILD TBI INDUCES PTSD‐LIKE BEHAVIOR AND CHRONIC NEUROPATHOLOGIES IN WILD‐TYPE AND APP/PS1 MICE
1UBC, Department of Pathology and Laboratory Medicine, Vancouver, Canada
2UBC, Department of Neurology, Vancouver, Canada
3UBC, Department of Mechanical Engineering, Vancouver, Canada
Keywords: CHIMERA model, beta‐amyloid, fear memory, spatial memory
EVALUATING THE FEASIBILITY OF THE SINGLE‐SITE TRACK‐TBI GERIATRIC PILOT STUDY
UCSF, San francisco, USA
Keywords: older adults, feasibility, geriatrics, inclusion criteria, exclusion criteria
PRE‐INJURY COGNITIVE AND FUNCTIONAL STATUS IN OLDER ADULTS WITH A TRAUMATIC BRAIN INJURY
UCSF, San francisco, USA
Keywords: older adults, functional outcomes, mild cognitive impairment
TRAUMATIC BRAIN INJURY AND ALZHEIMER'S DISEASE IN AGED MICE LEADS TO SIMILAR INCREASES IN SLEEP AND PERIPHERAL CD115 EXPRESSION
1BARROW Neurological Institute at Phoenix Children's Hospital, Phoenix, USA
2University of Arizona College of Medicine ‐ Phoenix, Child Health, Phoenix, USA
3The Ohio State University Neurological Institute, Columbus, USA
4Phoenix Veterans Affairs Health Care System, Phoenix, USA
The bidirectional feedback between peripheral and central inflammation drives pathological signaling in traumatic brain injury (TBI) and Alzheimer's disease (AD) with direct effects on sleep. Identifying specific inflammatory markers that link TBI, AD, and changes in sleep may elucidate mechanisms of chronic pathophysiology. We hypothesized that TBI in aged wild‐type mice lead to inflammation and disrupted sleep similar to an AD model and reduction of peripheral inflammation through remote ischemic conditioning (RIC; transient restriction of blood flow to a limb) would resolve sleep disruption. 18‐month 3xTg‐AD (B6;129‐Psen1 Tg[APPSwe, tauP301L]1Lfa; n = 22) and wild type (n = 34) mice were acclimated to non‐invasive sleep cages. Wild‐type mice received midline fluid percussion injuries (n = 27) or were naive controls (n = 7). One hour post‐injury mice were randomly assigned to a treatment cohort (3xTg‐AD RIC, 3xTg‐AD no‐RIC, TBI RIC, TBI no‐RIC). Mice received 4x5 minute sessions of RIC or control anesthesia. Blood was taken 1 day post‐injury (DPI) and mice were returned to sleep cages. At 5 DPI cognitive and affective behaviors were tested prior to tissue collection. TBI and 3xTg‐AD mice had significantly more cumulative sleep during the dark cycle compared to naive controls (F(2,43) = 9.62, p = 0.0004) with no effect of RIC at 1 DPI. At 5DPI, significantly more Cd115+ monocytes were in spleens and blood of wild‐type TBI and 3xTg‐AD mice compared to naive controls (spleen: F(2,23) = 4.742, p = 0.0189; blood: F(2,23) = 3.617, p = 0.0424), but were not significantly different between the two models. Further analysis will determine whether peripheral CD115+ expression predicts increases in sleep and whether reduction of Cd115+ ameliorates sleep changes. These data provide a new mechanistic link between TBI and AD pathophysiology. Funding: NIH‐R21‐NS096515, Arizona Alzheimer's Consortium, and T32‐AG044402
Keywords: Mouse Model, midline fluid percussion injury, Peripheral inflammation, Alzheimer's disease
MITOCHONDRIAL UNCOUPLING WITH 2,4 DINITROPHENOL CHANGES FROM A TOXIC TO THERAPEUTIC EFFECT WITH INCREASED AGE AT TIME OF SCI
1University of Kentucky, Physiology / SCoBIRC, Lexington, USA
2University of Kentucky, Neuroscience / SCoBIRC, Lexington, USA
Aging exacerbates spinal cord injury (SCI) through increased reactive oxygen species (ROS) damage. The contribution of mitochondrial‐derived ROS to this age‐dependent damage remains unknown. This work investigates how dysregulation of mitochondrial membrane potential with age effects ROS production after SCI. Graded doses (1.0‐, 2.5‐, 5.0‐mg/kg), of 2,4‐dinitrophenol (DNP; mitochondrial uncoupler) were delivered for 1‐week after T9 contusion (60 kdyn) SCI in young‐ (4‐month‐old; 4‐MO) and middle‐aged (14‐MO) mice. At 7‐days post‐injury (DPI) 1‐mg/kg/day of DNP exerted therapeutic benefits to 14‐MO SCI‐mice, but toxic effects to 4‐MO SCI‐mice. Specifically, trends towards improved myelin preservation, reduced inflammation, and lower 3‐nitrotyrosine (3‐NT; protein nitration product) accumulation were found in 14‐MO mice, with trends towards increased neurotoxicity only with 2.5‐ and 5.0‐mg/kg DNP treatment. Trends towards decreased myelin preservation, increased inflammation, and no effect on 3‐NT accumulation were found in 4‐MO mice, while all doses significantly reduced surviving neurons around the lesion. Treatment with 1.0‐mg/kg DNP significantly improved motor functions in 14‐MO SCI mice but worsened motor abilities of 4‐MO SCI mice during 28‐days of weekly functional monitoring. Next, macrophages were isolated from spinal cords at 6‐DPI and analyzed using Seahorse for mitochondrial function. Spared respiratory capacity and maximal respiration were reduced with age, which paralleled effects derived from pro‐inflammatory stimulation (LPS and INFg) of macrophages in vitro. Collectively, this data demonstrates that age dysregulates mitochondrial function after SCI, and that uncoupling mitochondria with DNP changes from a toxic to a therapeutic influence with increased age at time of SCI.
Funding Provided By: Craig H. Neilsen Foundation
Keywords: Mitochondria, 2, 4 Dinitrophenol, Aging, Spinal cord injury
AGE MODIFIES THE EFFECTS OF ANESTHETICS AND HYPEROXIA ON TRAUMATIC BRAIN INJURY (TBI) OUTCOMES
1University of Wisconsin, Anesthesiology, Madison, USA
2University of Wisconsin, Medical Genetics, Madison, USA
Despite its societal importance, experimental studies of TBI in aged organisms are sparse. TBI induced by blunt trauma in flies reproduces key characteristics of TBI in mammals. The volatile general anesthetics (VGAs) isoflurane (ISO) and sevoflurane (SEVO) differentially affect 24 h mortality (MI24) after TBI in young adult flies. Here we tested the hypothesis that age modifies the interaction between anesthetics, oxygen and TBI. We induced TBI using a high‐impact trauma (HIT) device. We compared mortality in young vs. old adult flies (1‐8 and 43‐50 days old, respectively). Flies were exposed to equivalent doses of ISO and SEVO for 2 h (i.e. either 4%h or 7%h, respectively) either before or after TBI. Anesthetics were administered either in 21% or 98% O2. The principal outcome measure was the mortality index 24 h after TBI ‐ MI24 [(percent mortalitytest) – (percent mortalitycontrol)]. We used generalized linear models to estimate mortality as a function of the experimental conditions. SEVO after TBI increased the MI24 by 27.6% in old (P = 0.0009) without significant effect in young flies. ISO after TBI had no significant effect in old but increased the MI24 by 26.1% in young flies (P = 0.0248). Anesthesia prior to TBI had no significant effect in old flies while reducing the MI24 by 48.6 and 51.4% for ISO and SEVO (P = 0.0010 and 0.0004, respectively) in young animals. 98% O2 either before or after TBI increased the MI24 only in old flies (by 13.1% and 37.8%, P = 0.0469 and <0.0001, respectively). Administration of anesthetics in conjunction with hyperoxia modulated the MI24 only in old animals. Our data suggest that aging influences the pharmacodynamics of VGAs and of hyperoxia and is consistent with a deleterious effect of hyperoxia in brain injury. Collateral effects of VGAs and hyperoxia should be considered in the design and interpretation of experimental studies of TBI.
Keywords: TBI, Drosophila melanogaster, volatile general anesthetics, outcome
A02 Axonal Injury
A MICROFLUIDICS‐BASED PHENOTYPIC ASSAY FOR THE DISCOVERY OF AXON‐PROTECTIVE AGENTS: A PROOF OF CONCEPT STUDY
1JHMI, SOM, Pathology, Baltimore, USA
2JHMI, SOM, Neurology, Baltimore, USA
3JHMI, SOM, Psychiatry and Behavioral Sciences, Baltimore, USA
Traumatic axonal injury is a complex process that engages perikaryal, axonal, vascular, and glial factors in a dynamic and temporally regulated fashion. In vitro systems that compartmentalize perikarya and axons can serve as useful tools to investigate some of the mechanisms of injury and also as assay systems to explore the efficacy of genetic or pharmacological manipulations to improve axonal integrity. Here we report a microfluidic‐chamber system as an in vitro bioassay for the effects of small molecules acting upon two axonal degeneration pathways (SARM1 and MAPKs). Mouse dorsal root ganglion or human ESC‐derived neurons were plated in microfluidic devices. Axons with vehicle or SARM1 or MAPK inhibitors (FK‐866, Sunitinib, GNE‐3511 and Tozasertib) were cut and images were taken at various time intervals. Images were analyzed for degeneration index (DI) which indicates percentage of fragmented axons. Time‐lapse images over 16hrs showed that, in absence of treatment, axons started to fragment at 2hrs post injury with progressive deterioration to a maximum at 17‐24hrs. Quantitative DI analysis showed that FK‐866 and Tozasertib showed early protection at 3.5, 6.5 and 17hrs, although protection was not apparent at 24hrs. Delayed FK‐866 administration 2hrs after injury showed significant protection at 6.5, 17, and even 24hrs. Sunitinib and GNE‐3511 did not show significant protection at any time point. Overall, treatment with FK866 offered robust protection of axons, in agreement with our in vivo data. However, this bioassay also showed a positive signal for Tozasertib and this opens the possibility that the MAPK pathway is also relevant in mediating axonal degeneration. In concert, microfluidic systems coupled with quantitative analysis of axonal degeneration are promising tools for the exploration of the molecular mechanisms of axonal degeneration and for screening of compounds with protective activity that may eventually be considered as drugs for traumatic axonopathy.
Keywords: Microfluidic device, SARM1, MAPK, Dorsal root ganglion cells, Human ESC‐derived neurons
NEUROFILAMENT LIGHT IS ASSOCIATED WITH BRAIN WHITE MATTER CHANGES IN PATIENTS WITH CHRONIC TRAUMATIC BRAIN INJURY
1National Institutes of Health, RMD, CC, Bethesda, USA
2Center for Neuroscience and Regenerative Medicine, Bethesda, USA
3Uniformed Services University of Health Science, Bethesda, USA
Keywords: Neurofilament Light, DTI, Volumetrics, White Matter
CEREBROSPINAL FLUID CHARACTERIZATION OF AXONAL INJURY, ASTROGLIAL ACTIVATION, AND AMYLOID DYSMETABOLISM OF ATHLETES WITH REPETITIVE
1Henry M Jackson Foundation for the Advancement of Military Medicine, Bethesda, USA
2Luleå University of Technology, Luleå, Sweden
3National Institutes of Health, Bethesda, USA
4Clinical Neurochemistry Laboratory, Mölndal, Sweden
Keywords: CSF, repetitive head trauma, tau, amyloid, astrogliosis
INVESTIGATING THE PATTERN OF AXONAL INJURY FOLLOWING TRAUMATIC BRAIN INJURY OF VARYING INTENSITY IN A LARGE ANIMAL MODEL
1The University of Adelaide, Adelaide, Australia
2University of South Australia, Adelaide, Australia
One of the most significant consequences of traumatic brain injury (TBI) is the development of diffuse axonal injury, which is consistently associated with worse outcome post‐injury. Axonal injury (AI) is induced by the induction of head rotational acceleration causing various brain regions to undergo differential shear, tensile and compressive forces that cause tissue deformation at high strain rates. This is influenced by the size of the brain, as inertial effect is dependent on brain mass. Thus, to facilitate a greater understanding of the pathophysiology of AI, modelling of TBI within larger gyrencephalic brains with more prominent white matter tracts is required. Consequently, this study characterised the distribution and degree of AI following TBI at varying intensities (11, 13 or 15 charge) in an ovine model. TBI was induced in anesthetized Merino wethers (n = 3/charge) to the right temporal area. Invasive blood pressure (BP) was monitored for 4 hours post‐injury, prior to formalin perfusion and brain removal. AI was assessed using immunohistochemistry for the amyloid precursor protein. Injury led to an immediate decrease in BP compared to shams, as calculated relative to pre‐injury baseline which was comparable across all injury groups (11 = −21.4752, 13 = −11.3236, 15 = −13.6672). BP returned to sham levels within 10 minutes post‐injury in all injury groups. Brain regions were assessed in 1cm anteroposterior segments, with the 15 charge producing significant AI at 3cm in the right internal capsule (sham = p<0.045, 11 = p<0.002, 13 = p<0.001) and right cingulum (naïve = p<0.005, sham = p<0.03, 11 = p<0.007, 13 = p<0.004). Moderate AI was also noted at 4cm anteroposterior in the reticular thalamic nucleus across all injury groups. Minimal AI was seen within the frontal white matter, corpus callosum, cerebellum and brainstem relative to shams, regardless of injury severity. This pilot study indicates mild diffuse TBI to be associated with an immediate drop in BP post‐injury. This contrasts with severe TBI where BP increases and indicates a differing physiological response depending on injury severity.
Keywords: Large Animal, Model Development, Pre‐clinical, Neuroanatomy
3D IN VITRO BRAIN TISSUE MODEL TO STUDY MECHANISMS OF TRAUMATIC BRAIN INJURIES
1Tufts University, Medford, USA
2Massachusetts General Hospital, Charlestown, USA
There is a high demand to understand the molecular sequelae inflicted after traumatic brain injuries (TBI). Currently, rodent models are mainly used for TBI research, however in vitro models due to their simplicity in manipulation, relevance, and high tunability can be used to identify the time‐dependent development of TBI pathology. We here developed an in vitro 3D TBI model that mimics the grey and white matter structures of the cortex to support the study of molecular mechanisms incited after TBI. We correlate our findings to animal injury models. The murine 3D in vitro brain model composed of embryonic neurons grown on a silk protein porous ring (d = 6mm) with a collagen core window (d = 2mm) embedded in hydrogel. Embryonic day 16 cortical neurons were used for in vitro model, adult 3‐6 months old mice for in vivo injuries and neuronal isolation for Western Blot (WB) analysis (C57BL/6 mice). Controlled cortical impact (CCI) was performed on in vitro and in vivo models under identical conditions as in vivo. The in vitro 3D brain tissue formed dense networks of neurons expressing Tuj1 and MAP2 neurite markers and Synapsin‐1 positive synapses. Our preliminary data suggests that network activity is compromised as early as 15 mins post‐CCI (50%, p < 0.05). Neural network structure defects (25% reduction, p < 0.05), glutamate and LDH release, a marker of cell health (increase 60%, p < 0.05) were observed after 4 hours post‐CCI. Key survival and death associated pathway Akt/mTOR signaling was reduced (p < 0.05) in both the 3D in vitro and the in vivo system (WB). Our in vitro brain tissue model mimics the in vivo neuronal response to trauma and allows us to study functional, structural and molecular changes over time after injury. Further research will aim to identify suitable targets for treatments post‐CCI. We thank the NIH (R01NS092847, P41EB002520) for support.
Keywords: Contusion, Immediate damage, In vitro model, Neurodegeneration
AXON‐MYELIN PATHOLOGY FOLLOWING EXPERIMENTAL TRAUMATIC BRAIN INJURY: SERIAL 3‐DIMENSIONAL ULTRASTRUCTURAL ANALYSIS
Uniformed Services University of the Health Sciences, Center for Neuroscience and Regenerative Medicine, Bethesda, USA
Myelinated axons crossing through the corpus callosum (CC) are particularly vulnerable to damage from traumatic brain injury (TBI), which results in diffuse axonal injury. Electron microscopy (EM) of myelinated fibers remains the gold standard method for analyzing ultrastructural changes of axon and myelin sheaths. However, analysis of single plane images limits interpretation of the proximal and distal pathology along individual axons. The present study addresses this gap by employing serial block‐face scanning EM in which sequential high resolution images are collected and aligned to produce three‐dimensional EM reconstructions (3DEM). Myelinated axons were reconstructed and analyzed within CC tissue volumes following a mild TBI. Adult C57BL/6J male mice received a single impact injury onto the closed skull at bregma. Similar to traumatic axonal injury in human TBI white matter, this model produces damaged axons interspersed among intact axons within the CC at 3 days and 6 weeks post‐injury (Mierzwa et al., JNEN, 2015). Sham‐operated animals served as controls. Our 3DEM confirmed expected pathology and revealed novel features along individual myelinated axons. Axons with advanced degeneration were fragmented and terminated at enlarged end bulbs. Damaged axons also exhibited varying extents of swellings and cytoskeletal breakdown, which were surprisingly interspersed among lengths of axon with apparently intact ultrastructure. Also, 3DEM demonstrated increased frequency of three forms of myelin pathology after TBI: a) partial myelin sheath loss at paranodal regions, b) demyelination of longer internodal segments, and c) myelin outfoldings. These outfoldings of compact myelin extended as flattened sheaths from internode regions into the adjacent tissue. Finally, our analyses revealed myelin debris within microglia in CC regions with dispersed axon damage after TBI, implicating myelin pathology in activation of phagocytosis. This ultrahigh resolution 3DEM analysis illustrates novel features of axon and myelin white matter pathology after TBI. These results are important for interpretation of axon cytoskeletal plasticity, white matter electrophysiological deficits and neuroimaging findings after TBI.
Keywords: Axon Degeneration, Demyelination, Myelin Outfoldings, Electron Microscopy, Oligodendrocytes, Microglia
A NOVEL APPROACH TO MEASURING REAL‐TIME CIRCUIT DYSREGULATION AFTER DIFFUSE BRAIN INJURY
1University of Arizona College of Medicine, Child Health, Phoenix, USA
2BARROW Neurological Institute at Phoenix Childen's Hospital, Translation Neurotrauma Program, Phoenix, USA
3Phoenix VA Healthcare System, Phoenix, USA
4University of Bath, Department of Biology and Biochemistry, Bath, United Kingdom
Each year, traumatic brain injury (TBI) impacts 69 million people worldwide. TBI induces global metabolic dysfunction, influencing brain oxygen consumption and neuronal activation thereby disrupting circuit function as indicated by functional magnetic neuroimaging. Methods evaluating circuit function after brain injury either have high temporal resolution or spatial resolution, but not both. These experiments evaluate a novel approach to measuring circuit dysfunction after TBI utilizing microelectrode arrays (MEAs) capable of measuring tissue oxygen (TO2) responses and local field potentials (LFP) with high temporal and spatial resolution, where TBI is expected to decrease circuit function. Young adult Sprague‐Dawley rats were subjected to midline fluid percussion injury or sham surgery. At 1 day post‐injury, MEAs coupled with amperometry were placed into the whisker barrel cortex of urethane anaesthetized rats to quantify TO2 and LFPs at a high temporal (< 1ms) and spatial (300μmx15μm) resolution during whisker circuit activation. Preliminary data indicate lower consumption of oxygen and decreased LFPs in injured vs. sham rats. Experiments validating this approach are ongoing for future use in longitudinal studies. The use of real‐time oxygen consumption and LFPs as a global biomarker of circuit dysregulation would be a novel approach to understanding the pathophysiology underlying the development and persistence of TBI‐induced morbidity.
Funding‐NIH(R01NS100793)‐PCH Mission Support
Keywords: Microelectrode Array, Oxygen Consumption, Local Field Potential, Circuit Function
DISCRETE TRAUMATIC AXONAL INJURY CAN INDUCE COMPLETE LOSS OF SYNCHRONY ACROSS AN IN VITRO MODEL OF MICROPATTERNED NODAL NETWORKS
University of Pennsylvania, Neurosurgery, Philadelphia, USA
Concussion commonly induces decreased processing speed and memory dysfunction, which are thought to reflect changes in the signal processing and conduction velocity across the brain's nodal network. In particular, selective traumatic axonal injury (TAI) to white matter axons has been implicated as a primary pathology that underlies network dysfunction in concussion. TAI spans a wide range of changes to individual axons, including pathological influx of calcium. Here, we examined how induction of this pathological process in a discrete portion of the network affects function across the whole network. We developed a micropatterned nodal network system in vitro, comprised of spatially distinct cortical neuronal nodes connected by axon tracts. Selective TAI within this network is induced by dynamic stretch of a single axon tract using mechanical parameters based on human concussion. Nodal neuronal and axonal integrity across the network was assessed at multiple time points following injury, with calcium levels and network activity monitored using the genetically encoded calcium indicator GCaMP6. Pre‐injury, network wide calcium synchronicity was consistently observed in cultures designed with a large number of axonal connections between nodal populations. Following injury, substantial increases in intra‐axonal calcium concentrations and swollen axonal profiles were observed in the injured axonal tract. Over several hours, a spreading of increased calcium levels was observed across all of the non‐injured neuronal nodes and axon tracts. In parallel, synchrony across the network was eventually lost by 24 h post‐injury. These data demonstrate a potential mechanism whereby even one discrete region of TAI can induce spreading corruption of signal processing leading to complete network dysfunction via loss of synchrony. This work was supported by the Paul G. Allen Family Foundation, NIH grants NS038104, EB021293, NS092398 and a PA CURE grant, 4100077083.
Keywords: network changes post TAI
ELUCIDATING THE ROLE OF N‐ACETYLASPARTATE IN TRAUMATIC AXONAL INJURY USING IN VITRO AND COMPUTATIONAL MODELS
University of Pennsylvania, Center for Brain Injury and Repair, Department of Neurosurgery, Philadelphia, PA, USA
Although N‐acetylaspartate (NAA) is the most abundant amino acid in neurons, its cellular roles have remained a mystery, until recently. Our group found one mechanism, where physiological concentrations of NAA markedly inhibit the formation of amyloid‐beta (Aβ) fibrils and break up preformed fibrils in vitro. This is intriguing since following traumatic brain injury (TBI), NAA concentrations are substantially decreased in the white matter at the same time that Aβ is produced and accumulates in white matter axons. The latter process has been linked with the rapid formation of diffuse Aβ plaques after TBI. Accordingly, lower NAA levels after TBI may permit greater Aβ aggregation. Here, we explored the potential role of NAA in Aβ aggregation in traumatic axonal injury (TAI). Using a computer model of Rosetta docking and molecular dynamics simulations, we found that normal axonal concentrations of NAA disrupt the structural stability of Aβ beta‐pleated sheets required for fibril elongation. This prompted us to explore the effects of NAA treatment on Aβ production and aggregation using an in vitro model of TAI. For the first time, we found that in vitro TAI induces the same Aβ genesis and accumulation in damaged axons that has been observed after TBI in humans and animal models, providing an expedient test bed model to investigate trauma‐induced mechanisms of Aβ metabolism. However, we observed that treatment of neuron cultures prior to injury with high concentrations of NAA or its hydrophobic methyl ester analog, NAA‐OMe, disrupted axon projections. Thus, while physiological levels of NAA might attenuate Aβ aggregation, treatment with high levels of NAA may come at the cost of interfering with normal protein‐protein interactions and interrupting the cytoskeletal integrity of axons. This work was supported by the Paul G. Allen Family Foundation, NIH Grants NS092398, NS038104, NS094003, EB021293 and PA CURE grant 4100077083.
Keywords: Axonal Injury, Neurodegeneration, Computational / Modeling, White Matter
TRANSPLANTED MICRO‐TISSUE ENGINEERED NEURONAL NETWORKS EXTEND AXONS INTO RODENT SPINAL CORD FOLLOWING SPINAL CORD INJURY
1University of Pennsylvania, Neurosurgery, Philadelphia, USA
2Corporal Michael J. Crescent VA Medical Center, Neurosurgery, Philadelphia, USA
Following spinal cord injury (SCI), the potential for de novo recovery is extremely limited, due to loss of complex axonal networks. The authors have previously reported the development of micro‐tissue engineered neural networks (micro‐TENNs) encased within agarose tubes as tools for repair of axonal pathways for brain disorders, however the use of these networks may restore spinal cord pathways as well. In the current experiment, we utilized an epidural cord compression injury model to generate an SCI at T6/7 in female Sprague Dawley rats (n = 36). Briefly, animals were anesthetized and a focal laminectomy was completed at L3‐4. A 2 French Fogarty® embolectomy catheter(Edwards Lifesciences, Irvine CA) was introduced into the epidural space at L3‐4 and advanced 5 cm to the level of T6/7. The catheter was maximally inflated for a period of five minutes. Control animals (n = 10) underwent injury alone and were euthanized at six weeks. Six animals were euthanized for humane endpoints and were not included in the final analysis. Experimental animals underwent a second surgery two weeks post injury for T6/7 laminectomy and stereotactic implantation of GFP‐expressing dorsal root ganglion (DRG) derived micro‐TENNs (n = 12), or acellular agarose tubes (n = 7). Animals with DRG micro‐TENNs were euthanized at one week (n = 4) or one month (n = 8) post implantation. Animals with acellular agarose implants were euthanized at one week (n = 3) and one month (n = 4). At euthanasia, animals were perfused with 10% formalin and were randomly assigned to classical histopathology with H&E and direct antibody to GFP, or to CLARITY protocol. GFP positive axons were noted in the host spinal cord at one month post implantation, demonstrating survival of DRG‐derived micro‐TENNs, and providing a proof of principle that micro‐TENNs may be a tool to restore axonal networks following SCI.
Keywords: spinal cord injury
A03 Biomarker
RELATION OF ACUTE PLASMA BIOMARKER LEVELS IN GCS 3‐15 TBI PATIENTS TO LOC, PTA, AND AOC: A TRACK‐TBI PILOT STUDY
1Baylor College of Medicine, Depts of PM&R and Neurosurg, Houston, USA
2Michael E. DeBakey Veterans Affairs Medical Center, Research, Houston, USA
3University of Florida, Brain Rehabilitation Research Center, Gainesville, USA
4SUNY Downstate Medical Center, Depts of Neurology and Pharm, Brooklyn, USA
5University of Calif San Fran, Dept of Neurosurgery, San Francisco, USA
6University of Texas School of Public Health, Dept of Biostatistics, Houston, USA
The aim of this study was to evaluate the sensitivity of five biomarkers (GFAP, UCH‐L1, T‐Tau, P‐Tau (Thr‐231), and P‐Tau: T‐Tau) to acute impairment of consciousness (AOC), loss of consciousness (LOC) and posttraumatic amnesia (PTA). Biomarkers were assayed on plasma samples from patients (GCS 3‐15) taken within 24 hours of injury and compared by LOC duration, PTA duration, and patient age as a confounder. No significant differences in any biomarker levels were observed when comparing impaired consciousness patients (GCS 3‐14) with unimpaired patients (GCS 15). Significant differences between time groups (0 min, <1 min, 1 – 29 min, >30 min) were observed for LOC duration and GFAP (C2 = 43.189; p < 0.001), UCHL1 (C2 = 16.156; p = 0.001), P‐Tau (C2 = 16.616; p < 0.001), and P‐Tau: T‐Tau levels (C2 = 18.059; p < 0.001). Findings were less pronounced when comparing by duration of PTA, with only GFAP producing a significant difference (C2 = 10.55; p = 0.014). Age was found to be a significant predictor of UCH‐L1 (R2 = 0.0925, p < 0.001), P‐Tau (R2 = 0.0857, p < 0.001) and P‐Tau: T‐Tau (R2 = 0.1039, p < 0.001). These findings suggest that age is an important confounder in UCH‐L1 and P‐Tau biomarker research. The usefulness of GFAP as a biomarker is strengthened by these findings, as it was most significantly associated with both LOC and PTA durations, and detected age differences between the participants.
Keywords: fluid biomarkers consciousness amnesia, Diagnostics
EFFICACY OUTCOME METRICS IN A LARGE ANIMAL TRIAL OF CYCLOSPORINE IN TBI ‐ DIFFUSION TENSOR IMAGING AND FLUID BASED BIOMARKERS
Michael Karlsson2, Nile Delso1, Zhihui Zhang6, Bryan Pukenas3, Eskil Elmer4,5, Magnus Hansson5, Kevin Wang6, Sanjeev Chawla3,
1Children's Hospital of Philadelphia, University of Pennsylvania, Anesthesiology and Critical Care Medicine, Philadelphia, USA
2Rigshospitalet, Neurosurgery, Copenhagen, DE
3Perelman School of Medicine at University of Pennsylvania, Radiology, Philadelphia, USA
4Lund University, Mitochondrial Medicine, Lund, SE
5NeuroVive Pharmaceutical AB, Lund, SE
6University of Florida, Emergency Medicine, Gainesville, FL
There is a need for novel outcome metrics that can bridge preclinical studies. Our objective was to assess Diffusion Tensor Imaging (DTI) and fluid based biomarkers as efficacy outcome metrics in a large animal study evaluating the neuroprotective efficacy of cyclosporine in TBI. The work builds upon our recently published study demonstrating reduced volume of brain injury by 35% in treatment group. A contusion injury was induced in piglets using a controlled cortical impact (CCI) device. Cyclosporine was administered continuously for 5 days, starting one hour post‐CCI (cyclosporine 20 mg/kg/d, n = 11; placebo, n = 13). The animals underwent DTI on a 3T MRI on day 5. Pixel‐wise parametric maps of mean diffusivity (MD), fractional anisotropy (FA), coefficient of linear (CL), planar (CP) and spherical (CS) anisotropy maps were generated. The mean values were computed from peri‐contusion tissues and were normalized with respect to contralateral normal brain parenchyma. Glial Fibrillary Acidic Protein (GFAP), as a measure of astroglia injury, and Neurofilament Light (NF‐L), as a measure of axonal injury, were studied as blood and cerebrospinal fluid (CSF) biomarkers, using a Quanterix SIMOA assay. Normalized FA (p = 0.027) and normalized CL (p = 0.018) was significantly higher in the treatment group, whereas normalized CS (p = 0.042) was a significantly lower in the treatment group. We observed a clear statistical trend of a decreased area under the curve (AUC) in the treatment group for NF‐L (p = 0.051) in CSF. Our findings suggest that DTI and NF‐L in CSF may be useful as outcome metrics in trials assessing neuroprotective drugs in TBI.
Keywords: cyclosporine, neuroprotection, traumatic brain injury
THE POTENTIAL FOR BLOOD‐BASED BIOMARKERS TO INFORM THE INTERPRETATION OF MICROSTRUCTURAL DAMAGE FOLLOWING TRAUMATIC BRAIN INJURY
GDIT/DVBIC, Silver Spring, USA
Traumatic brain injury (TBI) represents a significant challenge for military health care. An incidence of TBI is not an isolated event, but is better classified as a disease. While most patients recover in a matter of weeks, a nontrivial number continue to experience symptoms months or even years after injury. Biomarkers of TBI, such as neural proteins detectable in the blood or microstructural pathology detectable with imaging techniques, have been and continue to be heavily researched as objective indices of injury. Blood‐based biomarker assay development and detection technology is rapidly improving, allowing for identification of extremely minute concentrations of specific proteins. Originally investigated as diagnostic markers, it is increasingly apparent that blood‐based biomarkers may also be used to assess TBI recovery, prognosticate post‐concussive symptoms, facilitate treatment plans, and perhaps even identify those most at risk for sustaining a TBI. Likewise, magnetic resonance imaging (MRI) technology is rapidly advancing to the point where the integrity of axons following a TBI can be inferred. Microimaging techniques such as diffusion tensor imaging (DTI), diffusion kurtosis imaging (DKI), and neurite orientation dispersion and density imaging (NODDI) all can detect TBI‐related abnormalities in brain white matter. However, it remains unclear how particular physical indices measured by imaging – for example, mean diffusivity (MD) and fractional anisotropy (FA) – are related to the pathobiological consequence of TBI at the cellular level. While stereotypical patterns of MD and FA are observed as a function of time following injury, it is unclear how these patterns relate to injury severity, symptomatology, and the likelihood of ongoing neuronal dysfunction. Microimaging techniques are particularly sensitive to axonal injury, and certain blood‐based protein biomarkers, including tau and NF‐L, are integral to the axonal structure and function. Here, we describe the state of the science on the relationship between blood‐based and imaging biomarkers in relation to mild‐to‐moderate traumatic brain injury from the acute to chronic stage.
Keywords: Biomarker, Diffuse Tensor Imaging, mTBI, Axonal injury
ELEVATION OF NEURONAL OLFACTORY RECEPTORS IN HUMAN SERUM AND CEREBROSPINAL FLUID AFTER TRAUMATIC BRAIN INJURY
1Henry M Jackson Foundation/ Uniformed Services University, Pathology, Bethesda, USA
2University of Florida, Gainesville, USA
3Baylor College of Medicine, Houston, USA
4Uniformed Services University, Bethesda, USA
Traumatic brain injury (TBI) is defined as an injury to the brain by external forces which can lead to cellular damage and disruption of the normal central nervous system functions. The recently approved blood‐based biomarkers GFAP and UCH‐L1 can only detect injuries which are detectable on CT, and are not sensitive enough to diagnose milder injuries or concussion. Exosomes are small microvesicles which are released from the cell as a part of extracellular communication in normal as well as diseased state. The objective of this study was to identify the messenger RNA content of the exosomes released by the injured neurons to identify new potential blood‐based biomarkers for TBI. Human severe traumatic brain injury samples were used for this study. Control serum from healthy individuals was obtained from Bioreclamation Inc. RNA was isolated from neuronal exosomes and total transcriptomic sequencing was performed. RNA sequencing data from neuronal exosomes isolated from serum showed mRNA transcripts of several neuronal genes. In particular, mRNAs of several olfactory receptor genes were present at elevated concentrations in the neuronal exosomes. Some of these genes are OR10A6, OR14A2, OR6F1, OR1B1 and OR1L1. RNA sequencing data from exosomes isolated from CSF showed a similar elevation of these olfactory receptors. The data from these experiments suggests that damage to the olfactory neurons following an injury to the brain may cause the release of mRNA from these receptors in the exosomes. Hence, olfactory receptors can be further explored as biomarker for diagnosis of TBI. The opinions expressed herein are those of authors and are not necessarily representative of those of the Uniformed Services University of the Health Sciences, Department of Defense or, the United States Army, Navy, or Air Force and DMRDP.
Keywords: Biomarker, RNA sequencing, Exosomes
ACUTE DYSREGULATION OF THE CORTICAL METABOLOME FOLLOWING EXPERIMENTAL TRAUMATIC BRAIN INJURY AND THE EFFECT OF ETHYL PYRUVATE
1Loma Linda University, Radiology, Loma Linda, USA
2UCLA, Neurosurgery, Los Angeles, USA
It is well known that traumatic brain injury (TBI) alters cerebral metabolism which is associated with functional deficits. Metabolomics provides a mechanism to obtain comprehensive information about injury and the likelihood of therapeutic benefit based upon a pattern of biomarkers rather than a single biomarker. The purpose of this study was to describe early changes in the rat cortical metabolome using an untargeted approach to obtain a metabolic signature of injury and determine if the beneficial effects of ethyl pyruvate (EP) are related to changes in the cortical metabolome. We present progress made toward an additional interpretation of these data using lactate:pyruvate ratios as a surrogate marker of altered metabolism as an explanatory, statistical covariate to describe differences within and between group. Eighteen male rats with a moderate CCI and an additional 12 sham‐operated (incision only) rats received an i.p. injection of ethyl pyruvate (CCI‐EP; 40 mg/kg, n = 9) or phosphate buffered saline (CCI‐veh; n = 6) at 0, 1, 3, 6h post‐injury. At 24h animals were euthanized and extracts of the injury cortex were dissected and frozen/powdered in liquid nitrogen. Samples were shipped to Metabolon, Inc. (Durham, NC), where tissue samples were extracted and analyzed using Ultrahigh Performance Liquid Chromatography‐Tandem Mass Spectroscopy (UPLC‐MS/MS) or Gas Chromatography‐Mass Spectroscopy (GC‐MS). Two‐way ANOVA was used to identify metabolites exhibiting significant main or interaction effects of injury and treatment, and ANOVA contrasts were used to identify metabolites that differed significantly between experimental groups. CCI injury resulted in alterations in glucose, branch chain amino acid, lipid, and nucleotide metabolism. EP treatment increased metabolites associated with improvements in oxidative metabolism (acetyl CoA, malate, creatine phosphate) and redox homeostasis (glutathione). Current findings support and extend prior reports of injury‐induced alterations in cerebral metabolism and energetic and anti‐inflammatory effects of EP.
Supported by the UCLA Brain Injury Research Center and NINDS P01NS058489.
Keywords: CCI, ethyl pyruvate, metabolism, metabolomics
DEVELOPMENT OF RAT MODEL OF TRAUMATIC BRAIN INJURY INDUCED NEUROLOGICAL HETEROTOPIC OSSIFICATION
1Monash, Neuroscience, Melbourne, Australia
2University of Melbourne, Biomechanical Engineering, Melbourne, Australia
3Uniformed Services University, Anatomy, Physiology and Genetics, Maryland, USA
Neurological heterotopic ossification (NHO) occurs in approximately 15% of traumatic brain injury (TBI) patients and is characterised by the formation of bone (up to 1.5kg) in soft tissue. NHO typically forms in injured muscle and around joints, causing pain, nerve entrapment, soft tissue catabolism, and joint deformation. There are no predictive markers for NHO, therefore NHO can only be identified after the lesion has mineralised. The lack of biomarkers is in large part due to the challenges involved in studying this condition in humans, however, animal models allow for the control of these confounds. Here we aimed to develop a rat model of TBI‐induced NHO that mirrors the injury mechanics and post‐injury sequelae of NHO observed in humansand to identify plasma‐based markers that predict the development of NHO. Eight‐week old male rats were given a moderate‐severe TBI, a femoral fracture and a muscle crush injury (n = 12). Blood was collected at 2, 7‐, 21‐ and 42 days post‐injury and analysed using reverse phase protein microarray (RPPM). Rats were euthanized at 6‐weeks post‐injury and the formation of NHO was assessed via micro computed tomography. Six of 12 rats had formed NHO at 6 weeks post‐injury. The formation of ectopic bone was associated with elevated plasma levels of osteocalcin, a widely used marker of bone formation. Further, rats that developed NHO had significantly reduced plasma levels of interleukin‐6 (IL‐6) at all measured time‐points. These preliminary findings suggest that plasma levels of IL‐6 may serve as a predictive biomarker of the formation of NHO. Studies are underway to determine the cellular populations present in NHO lesions via histology.
Keywords: Neurological heterotopic ossification, Traumatic brain injury, Biomarkers, bone
RELATIONSHIP OF METABOLOMIC PROFILE AND FUNCTIONAL TRAJECTORY FOLLOWING MILD TRAUMATIC BRAIN INJURY IN OLDER ADULTS
1The University of Washington, Biobehavioral Nursing & Health Informatics, Seattle, USA
2Harborview Injury Prevention and Research Center, Seattle, USA
3The University of Washington, School of Medicine, Seattle, USA
Keywords: Metabolomics, Trajectory, Glasgow Outcome Score
SPORTS CONCUSSION AND BRAIN HEALTH: THE NEED FOR OBJECTIVE TESTS OF PATHOLOGICAL BRAIN INDICES
1Trinity College Dublin, School of Medicine, Dublin, Ireland
2Trinity College Dublin, School of Psychology, Dublin, Ireland
The impact of concussion on brain health is an escalating public health concern. Diagnosis relies on observable signs and symptoms, making it difficult to establish injury severity. Clinical and objective guidance is required via quantifiable biomarkers correlated with injury severity, in conjunction with sensitive, reliable neurocognitive assessment tools. Audio‐visual illusion paradigms such as the computer‐based ‘Sound Induced Flash Illusion’ (SIFI) test provide a means of assessing multisensory‐integration, correlating with underlying concussive pathology and functional and structural cerebral disturbances. The primary aim here was to determine the potential utility of the SIFI neurocognitive assessment as an objective test of concussion, with the secondary aim of assessing whether SIFI results correlated with known concussion biomarkers. 130 participants (74 = male, 56 = female) were recruited from collegiate contact and non‐contact sports, along with healthy age‐matched controls. 45 participants (35 male, 10 female) had a previous concussion, the majority (77.1%) sports‐related, with half of all concussions diagnosed by a clinician (50.5%). All participants were tested using the SIFI task and a blood sample was taken from a cohort of 53 participants for analysis of S100‐β and BDNF, suggested markers of TBI and brain health. Those with a history of four or more recorded concussions performed worse in the SIFI neurocognitive test in versus with no previous concussions; although at a p = 0.3 the result was not statistically significant. Gender was found to be the only independent variable of interest to have a significant effect on SIFI performance, with males performing better (p value = 0.049). Gender, cohort, and concussion range had no effect on circulating BDNF or S100‐β concentration. No significant correlations were found between the respective biomarkers and the SIFI experimental conditions (BDNF: r = 0.1382; p > 0.05; S100‐β: r = −0.1527; p > 0.05). These results highlight the need for a movement towards a more extensive multi‐dimensional and temporal assessment of concussion.
Keywords: Cognitive test, diagnostic marker, sport, S100B, BDNF
THE UTILITY OF BLOOD BIOMARKERS S100B AND BDNF AS A MEASURE OF BRAIN INJURY IN PROFESSIONAL RUGBY PLAYERS
1Trinity College Dublin, Medicine, Dublin, Ireland
2Leinster Rugby, Dublin, Ireland
Keywords: S100B, Rugby, BDNF, Exercise
DIFFUSE BRAIN INJURY INDUCED BIOMARKERS ASSOCIATED WITH TOXIC PROTEIN VARIANTS FOUND IN ALZHEIMER'S DISEASE AND RELATED DEMENTIA
1University of Arizona, Department of Child Health, Phoenix, USA
2Phoenix Children's Hospital, BARROW Neurological Institute, Phoenix, USA
3Phoenix VA Health Care Systems, Phoenix, USA
4Chemical and Materials Engineering Department, Arizona State University, Tempe, USA
Traumatic brain injury (TBI) leads to an increased risk of late onset Alzheimer's disease (AD) and related dementias (ADRDs), however, there are no methods to identify which TBI patients are at such risk. TBI can lead to toxic oligomeric variants of proteins associated with neurodegenerative diseases (Amyloid β (Aβ), tau, alpha‐synuclein (α‐syn), Tar DNA Binding Protein‐43 (TDP‐43)). We previously isolated antibody‐based reagents that selectively bind these protein variants and found high levels in blood and brain of human AD (late onset) samples and blood samples from TBI survivors, but not in age‐matched controls. Thus, we hypothesized that TBI leads to the accumulation of toxic protein variants and functional deficits indicative of an increased risk of late onset AD/ADRD. Adult male mice (C57BL/6J) were subjected to midline fluid percussion (n = 8) or sham injury (n = 6). Cognitive and sensorimotor function was assessed, and blood was collected at 1, 3, 7, 14, and 31 days post‐injury (DPI). Protein variant levels in blood were measured using a panel of 13 nanobodies against oligomeric Aβ, tau, α‐syn, and TDP‐43. Levels of toxic protein variants were significantly higher in brain‐injured mice at 1, 3, 7, and 14DPI and returned to uninjured sham levels by 31DPI. Bivariate correlation showed a significant negative correlation between latency to fall off the rotarod and protein variant levels (r = −0.326; p = 0.007). Tissue was collected at 31DPI and immunohistochemistry analyses are ongoing. TBI‐induced toxic protein variants may predict risk for developing late onset AD/ADRD and is necessary for translational therapeutics and rehabilitation strategies. These therapeutic strategies may identify at‐risk populations, delay the onset, and slow the progression of late onset AD/ADRD, where currently no such strategies exist.
Keywords: Traumatic Brain Injury, Alzheimer's Disease, Biomarker, Midline Fluid Percussion Injury, Mouse
CHARACTERIZATION OF SERUM TOTAL TAU FOLLOWING PEDIATRIC TRAUMATIC BRAIN INJURY
1University of British Columbia, Djavad Mowafaghian Centre for Brain Health, Vancouver, Canada
2University of British Columbia, Pathology and Laboratory Medicine, Vancouver, Canada
3The Hospital for Sick Children, CALIPER (Canadian Laboratory Initiative on Paediatric Reference Intervals) Program, Toronto, Canada
4University of Toronto, Department of Laboratory Medicine & Pathobiology, Toronto, Canada
5The Hospital for Sick Children, Department of Critical Care Medicine, Toronto, Canada
6The Hospital for Sick Children, Program in Neuroscience and Mental Health, Toronto, Canada
7University of Toronto, Institute of Medical Science, Toronto, Canada
8University of Toronto, Interdepartmental Division of Critical Care, Toronto, Canada
9The Hospital for Sick Children, Department of Paediatrics, Toronto, Canada
10University of Montreal, Department of Psychology, Toronto, Canada
11Ste‐Justine Hospital, Research Centre, Montreal, Canada
12Ste‐Justine Hospital, Division of Paediatric Intensive Care, Department of Paediatrics, Montreal, Canada
13Murdoch Children's Research Institute, Melbourne, Australia
14University of Melbourne, Department of Paediatrics, Melbourne, Australia
15Royal Children's Hospital, Melbourne, Australia
16Toronto Western Hospital, Krembil Research Institute, Toronto, Canada
17Monash University, Department of Paediatrics, Melbourne, Australia
18University of Melbourne, School of Psychological Sciences, Melbourne, Australia
Keywords: serum total tau
ELEVATING MICRORNA‐122 FOR TREATMENT OF TRAUMATIC BRAIN INJURY REGARDLESS OF ISCHEMIA OR BLEEDING
1University of California at Davis, Neurology, Sacramento, USA
2University of California at Davis, Neurological Surgery, Sacramento, USA
MicroRNAs (miRs) are very promising new generation drug targets due to their unique miR‐target binding that is different from the traditional ligand‐receptor.
Our pilot whole genome miR expression studies demonstrated that microRNA‐122 (miR‐122) is the most significantly decreased miR in blood after both lateral fluid percussion‐induced traumatic brain injury (TBI) and intraventricular autologous fresh blood‐induced intracerebral hemorrhage (ICH) in rats. These miR‐122 expression data suggest that elevating miR‐122 in blood has great potential to treat TBI, ICH and other injuries. Indeed, our previous studies have shown that intravenous (i.v.) miR‐122 mimic, wrapped in PEG‐liposomes, improves outcomes after middle cerebral artery occlusion (MCAO)‐induced ischemic stroke (IS) with a 6 hour time window.
In this study, we hypothesized that miR‐122 mimic improves outcomes after TBI and ICH, in addition to IS. Using experimental TBI and ICH models, our data show that miR‐122 mimic (2.4 mg/kg, i.v.) decreases BBB disruption at 24 hours after ICH and reduces cognitive deficits at 11‐15 days after TBI. Our miR‐122 targetome studies show that a set of miR‐122 target genes (Pla2g2a, Vcam1, Nos2, Rhbdf1, Olig1, Nrep) are responsible for the therapeutic efficacy of miR‐122 mimic on IS, while another set (Pla2g5, Ywhaq, Grm1) account for efficacy in ICH. Although the targetome study of miR‐122 on TBI is still ongoing, we predict that a different set of miR‐122 target genes are responsible for the efficacy of miR‐122 mimic to improve TBI outcomes.
In summary, our data suggest miR‐122 mimic can treat TBI, ICH and ischemic stroke. Therefore, the miR‐122 mimic treatment for TBI could likely be performed without brain imaging (e.g. in the ambulance, on the battlefield), no matter whether ischemia and/or bleeding occur as secondary insult(s).
Keywords: MicroRNA‐122 therapeutics, Traumatic brain injury
LEVERAGING TUMOR SUPPRESSOR MICRORNA‐125B TO TREAT TRAUMATIC BRAIN INJURY
1University of California, Davis, Neurology, Davis, USA
2University of California, Davis, Neurological Surgery, Davis, USA
Accumulating evidence shows oncogenes/kinases that have been widely studied in cancers can be leveraged to treat traumatic brain injury (TBI). The evidence includes: 1) oncogenes/kinases (e.g., Src, ROCK, CDK, others) are activated after TBI; 2) activation of oncogenes/kinases not only cause neuronal death via cell cycle re‐entry in mature neurons, but also mediate leukocyte infiltration and inflammation which results in BBB disruption after TBI; and 3) oncogenes/kinases inhibitors can improve TBI outcome, such as Src inhibitor (PP2), ROCK inhibitor (Y‐27632), CDK inhibitor (Roscovitine), and others. In this study, we hypothesized that tumor suppressor miR‐125b mimic improves multiple TBI outcomes, because miR‐125b decreases many oncogenes/kinases. Using lateral fluid percussion‐induced TBI model, we show that miR‐125b mimic (2.4 mg/kg, i.v. and 0.24 mg/kg, i.c.v.) blocks leukocyte infiltration, reduces cognitive deficits, and decreases neuronal death in hippocampus after TBI in rats. Our miR‐125b targetome studies show that a set of miR‐125b target genes (Mknk2, Alkk3, Neu1, others) contribute to the therapeutic efficacy of miR‐125b mimic on TBI. The preliminary mechanistic study data show:
Acknowledgements: This study was supported by NIH grants RO1NS089901(DZL).
Keywords: MicroRNA‐125b, miR‐taget pairs, Traumatic brain Injury
COMPARISON OF A PANEL OF 6 NEUROLOGICAL BIOMARKERS IN SERUM FOR TRAUMATIC BRAIN INJURY: A CENTER‐TBI PILOT ANALYSIS
1University of Florida, Emergency Medicine, Gainesville, USA
2University of Pécs, Department of Neurosurgery, Pécs, Hungary
3University of Messina, Deptartment of Neuroscience, ME, Italy
4University of Cambridge, Division of Anasthesia, Cambridge, UK
5University of Antwerp, Department of Neurosurgery, Edegem, Belgium
We identified a panel of six neuroprotein biomarkers, including not only the two recent FDA‐approved TBI diagnostic biomarkers GFAP and UCHL1, but also Tau, NF‐L, NSE and S100B and sought to test the clinical utilities using blood samples collected from the multicenter European study(CENTER‐TBI). Patients were differentiated by patient care pathways into three strata:ER stratum (discharged from emergency room), Admission stratum(hospital ward), and ICU stratum(admission to the intensive care unit). The first 1000 TBI participants with blood samples collected within 24 h post‐injury were subjected to GFAP, NFL, Tau and UCH‐L1 assays on Quanterix Simoa platform at University of Florida, and NSE and S100B assays on Roche Cobas 8000 analyzer in Hungary. This cohort contained 182 subjects from ER, 211 from admission and 607 from ICU stratum. The majority of patients in ER and Admission stratum are in the mild TBI category (GCS 13‐15) at 96.7% and 93.9%, respectively. Only 38.5% of ICU patients were considered as mild TBI. Consistently, all six biomarkers showed highest levels in ICU patients(p < 0.01). In addition, Admission patients had higher concentration of all biomarkers except NSE (p = 0.1) when compared to those at ER. The biomarker ROC curve for distinguishing TBI patients visited to ER then released vs. those admitted to hospital shows an AUC of 0.725 for GFAP, 0.696 for Tau, 0.656 for NFL, 0.626 for UCH‐L1, 0.603 for S100B(all p < 0.01) and 0.544 for NSE(p = 0.141). These results provide a conceptual framework for a blood‐based neurobiomarker panel in TBI patient triaging and care. To confirm these findings, we are continuing the biomarker analysis with the full 3,833 CENTER‐TBI cohort.
Keywords: CENTER‐TBI, biomarker, Tau, NFL, UCHL1, GFAP, S100b
A SPATIAL AND TEMPORAL REPRESENTATION OF NRF2 ACTIVITY IN MALE AND FEMALE MICE FOLLOWING CONTROLLED CORTICAL IMPACT INJURY
1Spinal Cord and Brain Injury Research Center, Lexington, USA
2University of Kentucky, College of Medicine, Lexington, USA
Traumatic brain injury (TBI) is an acute and chronic disease that currently lacks an effective treatment. One of the most substantiated secondary injuries that transpires from the initial insult is the upsurge of oxidative stress. Basic and translational research efforts have predominately focused on using male subjects, discounting the importance of studying sex as a potential variable. We can no longer assume that both sexes will benefit equally from the same therapy. The antioxidant transcription factor nuclear factor erythroid 2‐related factor 2 (Nrf2) is regarded as the master regulator of the mammalian antioxidant defense system. During times of elevated oxidative stress, Nrf2 transcriptional activity is upregulated to protect the cells from oxidative damage. Harnessing the Nrf2 pathway through pharmacological activators has become an attractive treatment for multiple neurological diseases, including TBI. The purpose was to establish a spatial and temporal representation of Nrf2 activation following severe TBI and to illuminate potential sex differences related to Nrf2 activation. Two cohorts of weight matched male and female CF‐1 mice underwent either controlled cortical impact (CCI) injury or sham operation. At 1, 2, 3, and 7 days post injury, the cortex and hippocampus ipsilateral to the injury were collected for mRNA and protein analysis. Results from qRT‐PCR revealed that following CCI injury there was an increase in the transcription factor Nrf2 and two of its downstream effectors, NQO1 and HO‐1 in the cortex and hippocampus of both sexes. Immunoblot analysis reflected similar results, though to a lesser degree. These findings indicate that the Nrf2 pathway remains a possible therapeutic target for TBI treatment in both males and females. This work is supported by NIH‐NINDS R01 NS100093; T32 NS077889
Keywords: controlled cortical impact, Nrf2, sex, translational research, mouse
BIOFLUID MICRORNAS AS BIOMARKERS FOR ASSESSING VASOSPASM RISK FOLLOWING ANEURYSMAL SUBARACHNOID HEMORRHAGE
1University of Kentucky, Sanders Brown Center on Aging, Lexington, USA
2University of Kentucky, Spinal Cord and Brain Injury Research Center, Lexington, USA
3University of Kentucky, Pathology & Laboratory Medicine, Lexington, USA
4University of Kentucky, Anesthesiology and Surgery, Lexington, USA
5University of Kentucky, Neuroscience, Lexington, USA
Aneurysmal subarachnoid hemorrhage (aSAH) is a medically complex, life‐threatening event caused by a ruptured intracranial aneurysm. Approximately one‐third of aSAH patients develop cerebral vasospasm 4‐10 days after aneurysm rupture, which results in extremely high morbidity and mortality. Currently, no validated biomarker is available in clinical practice to determine the risk for vasospasm in aSAH patients. MicroRNAs (miRNAs) are small, non‐coding RNAs that regulate gene expression post‐transcriptionally. MiRNAs have been implicated in virtually all human diseases, including aSAH, and can be found in extracellular biofluids including plasma, serum, and cerebrospinal fluid (CSF). MiRNAs are highly stable in these biofluids and are relatively easy to detect, both of which are ideal characteristics for biomarkers. We hypothesize that alteration of biofluid miRNAs may accurately reflect the pathophysiological events in aSAH patients who develop vasospasm. Therefore, CSF, plasma, and serum are rich sources for searching vasospasm biomarkers. The specific objective of our current study is to identify temporal changes of biofluid miRNAs in association with vasospasm risk following aSAH for rapid‐assessment of vasospasm risk. We examined miRNA expression patterns in CSF, plasma, and serum specimens collected from patients with and without vasospasm at 3 days and 7 days after aSAH. TaqMan miRNA analysis revealed a differential expression pattern of several miRNAs including such as miR‐107, miR‐146a, miR‐155, and Let‐7a. Importantly, the differential miRNA expression patterns were observed at the early time point (3 days after aSAH), allowing clinicians to see potential differences before vasospasm typically develops. Our study suggests that biofluid miRNAs are excellent candidates as biomarkers in predicting vasospasm risk, and have a strong translational application for the diagnosis and treatment of vasospasm.
Keywords: microRNA, vasospasm, aneurysmal subarachnoid hemorrhage, biofluid, CSF, plasma
EFFECTS OF GLYBURIDE ON BLOOD BIOMARKER IN THREE RAT TBI MODELS: FINDINGS FROM OBTT
1University of Messina, Neurosciences, Messina, Italy
2University of Florida, Gainesville, US
3WRAIR, Silver Spring, US
4University of Miami, Miami, US
5Pittsburgh University, Pittsburgh, US
6Safar Center for Resuscitation Research, Pittsburgh, US
7Banyan Biomarkers, Alachua, US
8VCU, Richmond, US
Glyburide (Gly) has shown promise in several studies of experimental traumatic brain injury (TBI) and the second highest scoring therapy tested in Operation Brain Trauma Therapy (OBTT). Although histological and functional measures remain central to assess therapeutic efficacy, there is interest in blood‐based biomarkers to provide complementary, objective and efficient information. Here, we assess the effects of Gly on blood levels of neuronal and glial markers and their relationships with histopathological and behavioral outcomes across the OBTT consortium. Adult male rats subjected to controlled cortical impact (CCI), fluid percussion (FPI), or penetrating ballistic‐like brain injury (PBBI) received a bolus 15min after‐injury, followed by a continuous infusion for 7d. Serum glial fibrillary acidic protein (GFAP) and ubiquitin C‐terminal hydrolase (UCH‐L1) were measured at 4h and 24h after‐injury. At 24h post‐injury, GFAP was increased across models vs sham. At 24h, in CCI and PBBI, GFAP was lower in Gly‐treated vs vehicle‐treated, whereas there were no differences in UCH‐L1 concentrations. Conversely, in FPI, Gly increased GFAP levels in treated rats at 4h and 24h, but attenuated neuronal injury as assessed by reduced UCH‐L1 at 4h. Contusion volume and hemispheric/cortical tissue loss were correlated with GFAP at both timepoints and with UCH‐L1 at 4h across models; cognitive disfunction correlated with GFAP at 4h and 24h in CCI and at 24h in PBBI; no other correlations with behavioral outcomes were found. Overall, Gly produced distinct biomarker patterns and correlations across models. Greater understanding of the mechanisms underlying biomarker findings in TBI models may enhance their pre‐clinical and clinical utility in TBI. Support: DAMD W81HWH‐14‐2‐0118;W81XWH‐10‐1‐0623.
Keywords: controlled cortical impact, fluid percussion, penetrating ballistic‐like brain injury
ON MICROCIRCULATORY BIOMARKERS OF SECONDARY CEREBRAL ISCHEMIA AT TRAUMATIC BRAIN INJURY
1Privolsky Research Medical University, Nizhny Novgorod, Russia
2University of New Mexico, Albuquerque, USA
Keywords: cerebrovascular resistance, cerebral arterial compliance, cerebrovascular time constant, critical closing pressure, perfusion computed tomography
EARLY NEUTROPHIL‐TO‐LYMPHOCYTE RATIO: ASSOCIATIONS WITH CHRONIC SYSTEMIC INFLAMMATION AND LONG‐TERM GLOBAL OUTCOME FOLLOWING TBI
1University of Pittsburgh, Physical Medicine and Rehabilitation, Pittsburgh, USA
2University of Pittsburgh, Safar Center for Resuscitation Research, Pittsburgh, USA
3University of Pittsburgh, Clinical and Translational Science Institute, Pittsburgh, USA
The role of peripheral immunity and the chronic embodiment of post‐traumatic inflammation in response to traumatic brain injury (TBI) are not well understood. However, increasing evidence suggests that ongoing derangements in humoral signaling, along with autonomic and hypothalamic‐pituitary function, may contribute to chronic peripheral immune dysfunction. We characterized early peripheral immune cell dynamics, their role in the systemic inflammatory response, and associated complications and outcome for a cohort of n = 183 adults with moderate‐to‐severe TBI. Absolute lymphocyte and neutrophil concentrations, as well as their neutrophil‐to‐lymphocyte ratios (NLR) over the first 20 days post‐injury, were abstracted from acute care medical records. We utilized group‐based trajectory (TRAJ) analysis to delineate the dynamics of NLR values over time and to stratify individuals into low and high NLR subgroups. Early NLR TRAJ membership was a point of stratification for assessing demographic, injury, inflammatory, and outcome variables. Worse (lower) Glasgow Coma Scale (GCS) scores and worse (higher) injury severity scores (ISS) were strongly associated with high NLR. Those in the high NLR TRAJ group also spent more time in acute care and on mechanical ventilation. Chronic inflammatory markers were assessed from n = 684 samples collected over the first 6 months post‐injury and showed significant NLR group differences in multiple inflammatory markers wherein comparatively higher levels occurred the high NLR TRAJ group (p < 0.05 all comparisons). Also, the high NLR TRAJ group was strongly associated with unfavorable Glasgow Outcome Scale and Disability Rating Scale scores at six months (p < 0.05 all comparisons). These findings were supported in multivariate analysis. NLR may serve as a novel acute metric in capturing injury‐related physiological burden and influencing long term outcome and chronic inflammatory profiles. Support: UPP‐Foundation, UPMC Trauma Registry.
Keywords: Lymphopenia, Neutrophilia, Acute Immune Cell Dynamics
PREDICTING TBI EXPOSURE HISTORY USING BIOMARKER AND NEUROIMAGING VARIABLES: A CENC STUDY
1University of Utah, Neurology, Salt Lake City, USA
2National Institutes of Health, Tissue Injury Branch, Bethesda, USA
3Virginia Commonwealth University, Physical Medicine and Rehabilitation, Richmond, USA
4University of Pennsylvania, Neurology, Philadelphia, USA
5USUHS, Neurology, Bethesda, USA
The Chronic Effects of Neurotrauma Consortium (CENC) collects multivariable clinical data in United States Service Members and Veterans. Preliminary results from CENC studies have identified important clinical risk factors that often herald worse outcomes, including multiple (≥3) lifetime mild traumatic brain injuries (mTBIs). The purpose of this proof‐of‐principle study was to use advanced machine learning methods to predict lifetime history of mTBI exposure using biomarker and brain imaging variables. 143 CENC participants were examined. Groups were defined by the total number of mTBIs experienced: No TBI, 1‐2 mTBIs, and 3 or more mTBIs. Plasma and peripherally circulating exosomal protein and brain imaging biomarkers (volumetrics and fractional anisotropy) were included in a random forest machine model to predict lifetime TBI exposures and to determine the relative predictive value of each feature. The balanced accuracy of classification ranged between 54‐66% across all TBI categories (chance prediction = 33%). Sensitivity and specificity ranged between 32‐57% and 72‐81% respectively. The most predictive features included a mix of blood‐based and neuroimaging variables, specifically plasma biomarkers (NfL, tau, VEGF, TNFα), exosomal protein cargo (IL‐10, IL‐6, tau, VEGF, p‐tau, TNFα, and Aβ40); and FA measures (right cerebellum, bilateral putamen, bilateral accumbens, bilateral and total PCR, SLF, CGC, and SFO). TBI diagnostic guidelines rely on history and do not include biomarkers or neuroimaging variables. The current investigation supports using advanced machine learning multivariate analyses that include blood and imaging biomarkers to predict remote mTBI clinical outcomes among Service Members and Veterans. This research was supported by grant funding from Department of Defense CENC Award W81XWH‐13‐2‐0095 and Department of Veterans Affairs CENC Award I01 CX001135.
Keywords: MRI, Volume, Diffusion, Exosomal, Plasma
ULTRASENSITIVE BLOOD TEST FOR P‐TAU IN CHRONIC TRAUMATIC BRAIN INJURY
1NIH, NINR, BETHESDA, USA
2HJF, Research, Bethesda, USA
3Meso Scale Diagnostics, MSD LLC, Rockville, USA
4USUHS, Neurolgoy, Bethesda, USA
5University of Pennsylvania Perelman School of Medicine, Neurology, Philadelphia, USA
Keywords: biomarker, dementia, tau, CTE
DETECTION OF SALIVARY CORTISOL AND CORTISONE IS PREDICTIVE OF OUTCOMES IN CONCUSSED AMATEUR BOXERS
UT Southwestern Medical Center, Surgery/ Burn, Trauma, Critical Care, Dallas, USA
Each year in the United States, approximately 1.7 million people sustain a traumatic brain injury (TBI). Of these TBI events, about 75 percent are characterized as being mild brain injuries (sports concussions, etc.). Previously, detection of neural markers of brain injury in blood has shown to be sensitive and reliable predictors of neurological outcomes. With respect to saliva biomarkers, the testing of brain biomarkers of injury within saliva of concussed athletes has been very limited. In this novel study, we hypothesized that steroid hormone levels are altered in the saliva of concussed athletes and are sensitive biomarkers for secondary brain injury shortly after TBI. Here, blood (8cc) and saliva (1‐2cc) was collected from concussed professional boxers (n = 25) within 30 minutes of injury. The plasma levels of neural markers of injury (creatine kinase B, NSE, and GFAP) were measured using the Meso‐Scale Diagnostic (MSD) electro‐chemiluminescence (ECL) array‐based multiplex format. The saliva DHEA, androstenedione, testosterone, cortisol, and cortisone levels were measured using mass spectrometry. We found that compared to the baseline time‐point and non‐injured controls, a significant increase in the saliva cortisol and cortisone levels were observed at ∼30 minutes after concussion. In addition, the observed increase in saliva cortisol and cortisone levels correlated with the number of blows to the head and Rivermead symptom scoring (day 7 after injury). Additionally, the saliva cortisone and cortisol levels correlated with the plasma levels of CKBB and NSE. In conclusion, this study describes the detection of cortisol and cortisone in saliva as potential brain injury biomarkers and inclusion on a brain biomarker panel. The detection of salivary brain injury biomarkers is less invasive and may prove to be beneficial for monitoring secondary brain injury in people that suffer a TBI.
Keywords: TBI, Saliva Biomarker, Cortisol, Cortisone
CORRELATION BETWEEN SERUM BIOMARKER LEVELS AND THALAMIC HISTOPATHOLOGY IN A MICRO PIG MODEL OF DIFFUSE BRAIN TRAUMA: AN OBTT STUDY
1Virginia Commonwealth University, Richmond, USA
2Messina University, Messina, Intaly
3University of Florida, Gainsville, USA
4Banyan Biomarkers, Inc., Alachua, USA
5University of Pittsburgh, Safar Center, Pittsburgh, USA
Blood biomarkers are promising tools for preclinical and clinical use following traumatic brain injury (TBI). Thalamic damage is suggested to play a central role in the pathogenesis of TBI and its various symptoms, but evidence remains limited. Here, we evaluated thalamic pathology and its relationship with serum biomarkers in a mild central fluid percussion injury (CFPI) model in adult micro pigs. This work is part of Operation brain trauma therapy (OBTT), a multi‐center multi‐species pre‐clinical therapy and serum biomarker screening consortium. Serum samples were collected prior to injury induction, and at 1min, 3hr and 6hr following CFPI. Semi‐quantitative microscopy assessments of axonal injury and alterations in immunolabeling of UCH‐L1 and GFAP were performed at 6hr following injury. There was no change in serum UCH‐L1 levels following TBI vs. baseline, while, consistent with prior experimental and human studies, GFAP, peaked at 6h post‐injury (∼8‐fold higher vs. baseline, p < 0.001). No correlation was found between serum UCHL‐1 and thalamic neuronal or axonal injury. Conversely, a strong negative correlation was found between changes in roundness of GFAP+ astrocytes and the IntDen/intensity of GFAP+ thalamic parenchyma (r = −0.94 p = 0.005), which, in turn, positively correlated with blood GFAP levels at 6h post‐injury (r = 0.89 p = 0.019). This preliminary study demonstrates that CFPI produces thalamic glial alterations with potential GFAP leakage into the extracellular space and ultimately into circulation, indicating a causal relation between thalamic glial status (activation and/or damage/leakiness) and circulating GFAP concentrations. It elucidates and provides important insights into the underlying thalamic pathophysiology and biomarker release‐kinetics following mild TBI. Finally, our studies across OBTT support fidelity between the rodent and micropig regarding serum GFAP's utility to monitor TBI pathologies. Funding: DAMD W81HWH‐14‐2‐0118; W81XWH‐10‐1‐0623 & WH81XWH‐14‐2‐0018.
Keywords: micro pig, central fluid percussion injury, Serum biomarker, GFAP, UCHL1, Immunohistochemistry
CASPASE‐3 ACTIVATION IS ASSOCIATED WITH CHRONIC TAU PATHOLOGY AND MICROVASCULAR REORGANIZATION IN THE HIPPOCAMPUS AFTER TBI
1Virginia Commonwealth University, Department of Neurosurgery, Richmond, USA
2University of South Florida, Department of Neurosurgery, Tampa, USA
3Banyan Biomarkers, Alachua, USA
4Single Breath, Gainesville, USA
Keywords: Hippocampus, CCI, Cleaved‐caspase‐3, tau
A04 Biomechanics
IN VITRO QUANTITATIVE ANALYSIS OF NEURONAL‐STRUCTURAL AND ELECTROPHYSIOLOGICAL CHANGES FOLLOWING MECHANICAL LOADING
Army Research Lab, Aberdeen Proving Ground, USA
Understanding tolerance of brain tissue is necessary to design the best protection to prevent Traumatic Brain Injury. The complex structural and functional interactions in the brain make in vivo evaluations of the tolerance extremely difficult, making in vitro models more appropriate. The objective of this research was to obtain an injury criteria threshold leading to the onset of neuronal dysfunction by simultaneous measurement of electrophysiological outcomes and biomechanical changes at different strains levels. This work utilized a new state‐of‐the‐art mechanical stretcher: the MicroElectrode Array Stretching Stimulating und Recording Equipment (MEASSuRE) which delivered a tailorable equi‐biaxial load to cultures while simultaneously recording electrical activity and imaging the deformation. Initial work characterized the development of cultures on the stretchable microelectrode arrays used with the MEASSuRE system. Low (50cell/cm2) and high (100cell/cm2) density cultures containing both primary neurons and glia were evaluated to determine when spontaneous electrophysiological function developed in vitro. Cultures were then subjected to a biaxial stretch of increasing strain (10%, 20%, 30%) at 50s−1 using the MEASSuRE device. Actual strain of the cells was verified using high speed video (1000fps) during the stretch and matched the desired strain. To obtain the unique cellular responses of each cell type after the mechanical insult, individual cells were tracked prior to and at various time points post‐stretch. Acutely, there was increased evidence of neurite undulation followed by beading and breakage, and a reduction in total neurite length after stretching at later time point. In glia, morphological changes such as vacuolization and disruption of glial filaments were observed. Evidence of structural alterations increased with increasing strains. To quantify changes in electrophysiological activity before and after mechanical loading, high‐density, mixed cultures were plated on stretchable microelectrode arrays and subjected to increasing strain. In summary, we developed a methodology to produce graded, strain‐related injuries in cultured cells and evaluate their structural and electrophysiological response. This methodology is designed to determine the thresholds of injury, both structural and electrophysiological, to support developing assessments of brain injury.
Keywords: In vitro, Biomechanics, Electrophysiology, TBI
REGIONAL AND DIRECTIONAL CHARACTERIZATION OF PORCINE BRAIN TISSUE MECHANICAL PROPERTIES AT LARGE DEFORMATIONS
1Columbia University, New York, USA
2NorthShore University Health System, Evanston, USA
3MEA Forensic Engineers & Scientists, Toronto, Canada
4National University of Singapore, Singapore, Singapore
Traumatic brain injury (TBI) is a prevalent condition worldwide. Computational models have been developed to predict brain tissue response to TBI to improve protection strategies. For these models to predict a biofidelic response, brain tissue mechanical properties must be accurately represented. We previously found regional and directional differences in shear moduli in porcine brain tissue at 10% strain. The current study extends this analysis to larger deformations more relevant to TBI. Coronal, sagittal, and horizontal brain tissue slices were generated from euthanized pigs. Indentation testing was performed using a custom designed indentation device. Multistep indentation depths of 40, 80, and 120 μm were reached, corresponding to 10, 20, and 30% strain. Indentations were performed within each region including the brainstem, cerebellum, cortex, hippocampus, and thalamus. The load and displacement histories were collected using a custom LabVIEW program. The nonlinear behavior was modeled using the quasilinear theory of viscoelasticity (QLV). The load was defined as a function of the reduced relaxation function, load history and instantaneous elastic response. Various constitutive models were used to express the instantaneous elastic response to identify the optimal fit to the data. The QLV model provided a better fit to the data than the linear model for stress with respect to strain, reaffirming the nonlinear behavior of brain tissue response. The polynomial and Mooney Rivlin constitutive equations more accurately modeled the nonlinear response than the Ogden constitutive equations. There were regional differences in the normalized shear moduli in the slices excised in each plane but additional statistical analysis is required. Further analysis will help determine if any directional differences in shear moduli exist in each region of brain tissue. This analysis can be applied to computational models of pig TBI to better understand injury biomechanics in large animal models of TBI.
Keywords: indentation testing, quasilinear theory of viscoelasticity, shear modulus, porcine brain tissue, instantaneous elastic response
ASSOCIATION OF PHYSIOLOGICAL VARIABLES WITH SUBCONCUSSIVE HEAD IMPACTS IN HIGH SCHOOL AMERICAN FOOTBALL
1Indiana University, Department of Kinesiology, Bloomington, IN, USA
2Washington Township Medical Foundation, Department of Sports Medicine, Union City, CA, USA
3Indiana University, Department of Epidemiology and Biostatistics, Bloomington, IN, USA
4Indiana University, Program in Neuroscience, Bloomington, IN, USA
5Indiana University, Department of Applied Health Science, Bloomington, IN, USA
Subconcussive head impacts, or impacts that do not present with concussion symptoms, are gaining traction as a major public health concern. However, there is a gap in knowledge about the contribution of physiological variables, such as muscle damage and physical exertion, to neurological measures used to assess subconcussive impact‐dependent changes. The unknown contribution of physical exertion and strenuous exercise is often listed as a limitation in field studies of subconcussive head impacts. The purpose of this investigation was to examine the relationships between subconcussive head impact frequency and magnitude and measures of physical exertion and muscle damage. Fifteen high school football players wore mouthguards with triaxial sensors in order to quantify the linear and rotational accelerations of every head impact sustained throughout one season (practices and games). Additionally, serum samples were collected at twelve time points (pre‐season, pre‐ and post‐competition for five in‐season games, and post‐season) and assayed for CK‐MM, a skeletal muscle‐specific isoenzyme of creatine kinase. Subjects wore heart rate monitors during the five games, and heart rate data were used to estimate physical exertion in terms of excess post‐exercise oxygen consumption (EPOC). Mixed‐effect regression modeling showed significant and positive associations between CK‐MM and subconcussive head impact kinematic variables, in addition to a significant and positive association between CK‐MM and EPOC. When investigating subconcussive head impacts, the effects of muscle damage should be considered when using correlated outcome measures, such as inflammatory biomarkers and vestibular assessments.
Keywords: subconcussive head impacts, physical exertion, muscle damage, creatine kinase, American football
HIGH GRAVITY HEAD IMPACTS TO THE SIDE AND REAR IN AMERICAN FOOTBALL CAUSE VISIBLE DEFICITS IN ATHLETES
1Prevent Biometrics, Chief Science Officer, Minneapolis, USA
2Cleveland Clinic, Neurosurgery, Cleveland, USA
3University of Pittsburgh, Neurosurgery, Pittsburgh, USA
In the United States, there are approximately 50 million athletes who participate in the “living laboratory” of a sporting environment and are at risk of sustaining head impacts on a routine basis. Hundreds of thousands – and perhaps millions – of concussion impacts occur annually. We used a head impact monitoring system embedded in an American football player's mouthguard to quantify single head impacts with high accuracy and precision. Laboratory tests were performed to confirm data fit a linear model of the form y = mx+b within the ranges of the on‐field exposure. On the playing field we measured head impacts in n = 445 American football player‐games. While all true positive head impacts were video‐verified, the most attention was paid to any athlete who sustained a single or multiple set of impacts doses that resulted in visible and/or self‐reported functional impairment per the NFL's “No‐Go” criteria. In n = 445 player‐games of American football we observed head impact behavior and video‐verified single and cumulative impacts that caused obvious functional deficits per the NFL's “No‐Go” criteria. A total of eleven (11) athletes sustained impairment. Impacts to the side and rear with kinetic energy transfer ranging from 40 to 115J caused impairment, along with multiple impacts totaling kinetic energy transfer of 100J to 320J. Interestingly, single forehead impacts in the range of 50J to 70J did not cause obvious functional impairment upon video review. All these single/cumulative impact energy doses were well above the median single impact dose of 6J and cumulative dose of 36J. This suggests (1) a potential directional sensitivity of the brain to head impacts, with side and rear impacts at the same impact energy being apparently more damaging than comparable forehead impacts in American football, and (2) a cumulative impairment level based on a day's‐worth of energy doses absorbed by the athlete primarily in the sagittal plane.
Keywords: concussion, tbi, American football
HUMAN BRAIN DEFORMATION DURING DYNAMIC ROTATION OF THE HEAD
University of Virginia, Center for Applied Biomechanics, Charlottesville, USA
Finite element (FE) models of the human brain are the state‐of‐the‐art technique for simulating real‐world head impacts to assess brain injury risk, investigate neurotrauma mechanisms, and develop countermeasures. However, these models must be validated to human brain deformation. Recently, a technique was developed using sonomicrometry to record in‐situ human brain motion (Alshareef et‐al., 2018). Leveraging this technique, the objective of this study was to generate a dataset of brain deformation for six specimens under various head kinematic conditions. For each human head‐brain specimen, sonomicrometry crystals were implanted into the brain and used to quantify brain tissue displacement relative to the skull. A dynamic rotation was applied to the specimens using a custom‐designed test device. Four severities of rotation ranging from a peak angular velocity of 20 – 40 rad/s with durations of 30 – 60 ms were applied about three directions for a total of 12 tests per specimen. All tests were completed within 72 hours post‐mortem. This is the first study to quantify 3D brain deformation in multiple human specimens in response to a range of rotations in all three anatomical planes. Sonomicrometry provided highly repeatable 3D displacement data of the in situ motion of the brain, totaling 5000 brain deformation time‐histories. The plethora of data allows for comparisons of injury risk across loading severity, rotation direction, and brain region. Brain deformation was dependent on peak angular velocity, duration, and loading direction – axial rotation resulted in the greatest deformation. Peak‐to‐peak displacement amplitudes reached as high as 23 mm in the most severe loading case. The availability of accurate, 3D deformation data of the human brain will help improve the biofidelity of FE brain models and lead to better techniques for predicting and mitigating brain injury. These methods provide a framework using sonomicrometry to acquire experimental data in the brains of human and animal specimens, and will lend insight into the deformations the brain experiences during impact.
Keywords: Brain deformaton, Sonomicrometry
ESTABLISHING A TISSUE‐LEVEL BRIAN INJURY THRESHOLD USING A SUBHUMAN PRIMATE HEAD MODEL
Wayne State Univ, Biomedical Engineering, Detroit, USA
The Head Injury Criterion based on head translational acceleration is the current federal vehicle safety standard for head protection. Rotational head motion induced diffuse axonal injury (DAI) has been successfully reproduced in the subhuman primate models in the 80's. To protect brain from rotational injury, there is need to develop tissue‐level based injury criterion. The objectives of the current study were to develop a Finite Element (FE) model of the subhuman primate head and to develop the injury estimates by correlating the model‐predicted biomechanical responses with the foci of DAI in experimental animals. The FE model of the Rhesus monkey head/brain simulating all essential anatomical structures was developed using MRI images. The model consists of >500,000 elements. The head accelerations from the experimental animals impacted in the coronal, oblique and sagittal planes of similar magnitude were simulated. The coronally‐rotated head produced maximum principal strain(MPS) at 45% and 54% higher for brainstem, 8% and 48% higher for corpus callosum, 13% and 22% higher for white matter as compared to oblique and sagittal rotations, respectively. The higher MPS correlated to the region of observed severer axonal pathology. Based on the correlation, MPS 1.3 was proposed for the threshold of mild DAI. By translating the threshold to a validated FE human head model (GHBMC model), the human head model was accurately predicted no injury for the simulated human volunteer tests as well as the vehicle crash tests. In contrast, the new Brain Injury Criterion (BrIC), currently proposed by the US government which is a rotational acceleration based injury criterion, predicted >50% of AIS‐2 brain injury risk. The FE monkey model developed is capable of differentiating severity of the axonal damages according to the brain strain in respond to the head rotations in different directions. This tissue‐level threshold established by the direct correlations of the model prediction with the DAI pathology in experimental animals can be used to improve the predictability of the current FE human head model in predicting rotational brain injury.
Keywords: Primate head model, Rotational brian injury criterion, Tissue level strain measures
ASSESS THE ADEQUACY OF A BRAIN‐MASS BASED SCALING TECHNIQUE FOR DEVELOPING ROTATIONAL BRAIN INJURY CRITERIA
Wayne State Univ, Biomedical Engineering, Detroit, USA
Scaling techniques were often used to scale the biomechanical responses of human surrogates to human population of different ages and genders to establish injury criteria. The new Brain Injury Criteria (BrIC) proposed by the NHTSA were based on human head finite element (FE) modelling of the experimental brain injury in animals by scaling the mechanical loading experienced by the experimental animals to a FE human head model. This study was to investigate the adequacy of using mass‐based scaling method without considering the anatomical/geometrical difference to translate animal data to human. Biomechanical responses of the brainpredicted by the three FE head models: a rhesus monkey head model (Model_1), a scaled Model 1 to a larger monkey head having brain mass of a 50th% human male, and a 50th% male head model (Model_3) were compared. The rotational head acceleration (Input_1) reported from monkey brain injury experiments was simulated by the Model_1. For Models 2&3, Input_2 was applied which is the Input_1 scaled by factor of 0.263 and 1.95 for magnitude and time‐duration, respectively based on mass scaling. The Model_1 with Input_1 yielded similar maximum principal strain (MPS) in the brainstem, corpus callosum and subcortical white matter as those from the Model_2 with Input_2. The MPS locations/patterns were nearly identical between the two monkey mdoels. In contrast, Model_3 with Input_2 (human model) showed 45‐48% difference in MPS magnitude as well as strain localization patterns from the two monkey model cases. The similarities in resulting brain responses between the monkey models of two different sizes demonstrate that mass‐based scaling for scaling rotational accelerations works well within the species of identical anatomy/geometry. The profound differences in brain responses found when using scaled experimental data simulated by the human head model and the experimental data simulated by the same animal model confirming that the scaling method used in the development of BrIC is unreliable owing to the geometrical, shape and neuraxis differences in the brains between the subhuman primate and the human.
Keywords: FE model, Mass scaling, Rotational brain injury criterion
VALIDATION OF THE STRAIN RESPONSE IN THE BRAIN: RECENT UPDATE OF THE GHBMC M50 HEAD MODEL
Wayne State Univ, Biomedical Engineering, Detroit, USA
A number of finite element (FE) head models have been developed to improve the prediction of traumatic brain injury. Development of brain injury criteria requires a FE head model that has detailed anatomical and material representation of a human head and robust performance under various impact conditions. The GHBMC M50 head model introduced in 2013 has been validated against various cadaveric impact data. The model has the capability of predicting skull and facial fractures, contusion, diffuse axonal injury and acute subdural hematoma. The current study reports the new validation study against available cadaveric brain strain data and optimized brain tissue properties for improving the biofidelity. In cadaver tests, the maximum principal strain (MPS) was calculated from 12‐triads formed by a cluster of 7 radio‐opaque targets implanted in the brain. All 8 cadaver impact tests were simulate. The head model predicted node displacements at the NDT locations were used to calculate the model MPS results. The viscoelastic properties of brain tissues were optimized to improve the correlation. The head model predicted MPS in the brain was 0.05‐0.10 while as the cadaver MPS was 0.04‐0.09. The overall temporal responses of the model MPS matched to most of the cadaveric responses except for a couple of cases where presumably the deviation of the node locations in the FE model compared to the target locations in the cadaver brain could affect the displacement results, subsequently the strain calculation. The average objective CORA rating was 0.52. It exceeded the CORA results reported by another group using a different head model recently. The current GHBMC M50 head model version 5 has been validated against localized strain responses in the brain according to the newly available data obtained from cadaveric head impact tests. The material properties of the viscoelastic brain tissues defined for the model have been optimized to mimic the material behaviors under relevant impact conditions. This enhancement will add the improved capability to the current model in predicting tissue‐strain mediated brain injury.
Keywords: Finite Element Head Model, Model validation, Brain strain validation, CORA rating, Tissue level injury predictors
AN OPTIMIZED HEAD INJURY MODEL VALIDATED AGAINST THE FULL SPECTRUM OF BLUNT IMPACT CONDITIONS FOR THE BRAIN
Wei Zhao,
Worcester Polytechnic Institute, Worcester, USA
Rigorous validation of a human head injury model is critical for its effective use. However, the majority of head injury models only validate against extremely high‐rate cadaveric impacts but do not attempt to validate against in vivo head rotations relevant to sub‐concussion. In addition, data from mid‐rate cadaveric impacts are emerging, but have not been used in validation. The objective of this study was to optimize the Worcester Head Injury Model (WHIM) to validate against the full spectrum of blunt impact conditions for the brain using 9 high‐rate cadaveric impacts, 8 mid‐rate cadaveric impacts most relevant to those on the sports field, and 3 tests of in vivo head rotations that are on the same order of impact severity with respect to sub‐concussive impacts. Specifically, an anisotropic brain material property model based on whole‐brain tractography derived from diffusion tensor imaging was implemented into a re‐meshed, high resolution brain mesh. The material property was then optimized to maximize the Correlation Analysis Score (CORA) based on relative brain‐skull displacements using the 9 high‐rate cadaveric impacts (CORA optimized to an average of 0.707). The optimized WHIM was successfully cross‐validated using displacement data from 8 mid‐rate cadaveric impacts (7 of which were non‐contact, pure rotation impacts conducted recently using either an improved neutral density target method or a sonomicrometry approach; CORA of 0.567–0.879). Finally, it was further successfully cross‐validated against cadaveric strains and strains from 3 recent tests of in vivo head rotations. This was the first attempt to comprehensively validate a head injury model across the full spectrum of blunt impact conditions for the brain. Nevertheless, uncertainty in strain responses remains, suggesting the need to investigate how best to coordinate with experiments for the next iteration of model development in the future.
Keywords: head injury model, model validation, sub‐concussion, head rotation, contact sports
A05 Blast
EFFECTS OF REPEATED BLAST‐INDUCED TRAUMATIC BRAIN INJURY IN RAT ORGANOTYPIC HIPPOCAMPAL SLICES ON LONG TERM POTENTIATION
Columbia University, Biomedical Engineering, New York, USA
Repeated blast induced traumatic brain injury (TBI) in rat organotypic hippocampal slice cultures impaired long term potentiation (LTP) to a greater extent than a single blast injury. The current study investigated the effects of repeated primary blast loading on electrophysiological function with varying inter‐injury intervals and recovery days following the second blast. Using a compressed‐gas driven shock tube, cultures were exposed to either sham or repeated mild blasts (at either level 1, 2 or 3) at a variety of inter‐injury intervals. Following the final blast injury and at a variety of recovery periods, electrophysiological recordings were acquired using 60‐channel microelectrode arrays. LTP was induced in the CA1 hippocampal region via stimulation of the Schaffer Collateral pathway. LTP was calculated as the percent difference in the average of the last 10 minutes of the pre‐ and post‐induction recordings. In the groups that we studied, our data generally suggests that a minimum recovery period of 6 days is necessary to allow for the full recovery of LTP following a mild to moderate repeated blast injury. Confirming our previous studies, if a second blast injury is applied prior to 6 days, LTP deficits are aggravated. LTP recovered to a greater extent as the inter‐injury interval increased, suggesting that the longer the time between blasts, the better the outcome. In our experiments with three blast injuries at 1 day intervals, there were no greater LTP deficits than when the slices were exposed to only two blasts, suggesting that repeated blast exposures impairs LTP only up to a certain extent in our system. For military personnel who encounter a blast injury, this data could better inform return‐to‐duty criteria. Future studies will examine molecular mechanisms responsible for greater LTP deficits after repeated blasts.
Keywords: Repeated blast, Long term potentiation, organotypic hippocampal slice cultures, Shock tube
CHANGE IN HEALTH RELATED SYMPTOMS FOLLOWING ENVIRONMENTAL BLAST EXPOSURE DURING HEAVY WALL BREACHING TRAINING IN A MILITARY COHORT
1Defense and Veterans Brain Injury Center, Silver Spring, USA
2Walter Reed Army Institute of Research, Silver Spring, USA
3Naval Hospital Camp Pendleton, Camp Pendleton, USA
4Oak Ridge Institute for Science and Education, Oak Ridge, USA
Keywords: Environmental blast exposure, Breacher training, Health symptomology, Service members
DISRUPTION OF BLOOD‐BRAIN BARRIER IN A RAT MODEL OF BLAST‐INDUCED TRAUMATIC BRAIN INJURY
1Naval Medical Research Center, Silver Spring, USA
2Henry Jackson Foundation, Bethesda, USA
3Uniformed Services University of Health Sciences, Bethesda, USA
4University of Virginia, Charlottesville, USA
Blood‐brain barrier (BBB) breakdown results in the entry of serum proteins and other circulating factors into the brain fluid microenvironment with subsequent cellular injury. The incidence of blast‐induced traumatic brain injury (bTBI) has been a persistent risk for neurological impairment in the military population, yet its detailed pathophysiology, including BBB damage, remains unclear. We used immunohistochemistry and molecular assays to investigate the time course of blast‐induced BBB changes. Anesthetized rats received a single blast overpressure (BOP) exposure of 130 kPa and were euthanized 2 hours (h), 24 h, 3, 14, and 28 days post‐blast (n = 5/group). Sham animals were exposed to all procedures except BOP and were euthanized 2 h later (n = 5). The localization of BBB tight junction (TJ) proteins ZO‐1, claudin‐5, occludin in blood vessels was visualized by double‐labeling with vascular smooth muscle marker smoothelin. In separate groups of animals, BOP‐induced BBB disruption 24 h post‐BOP was further examined by 3,3′‐Diaminobenzidine (DAB) staining to assess functional changes in BBB. Biotinylated dextran (10 kD) was intravenously administered in sham or BOP‐exposed rats (n = 5/condition). Another study assessed metalloproteinase‐9 (MMP‐9) at 2 and 24 h after BOP or sham exposure. Compared with shams, iimmunohistochemistry and western blots showed TJ proteins were significantly decreased 2 h post‐BOP and remained low 24 h post‐BOP but recovered thereafter. These changes were paralleled by an increase in MMP‐9 that followed the same time course. Specifically, MMP‐9 levels increased in serum and brain tissue 2 and 24 h post‐BOP. Extravasation of dextran was observed in the brains of BOP‐exposed but not sham rats, indicating blast‐induced BBB disruption. Our findings show BBB disruption that is tightly linked to changes in MMP‐9 may play a role in early formation of neuropathology associated with bTBI.
Keywords: traumatic brain injury, tight junction proteins, metalloproteinase‐9
TRANSPORT RELATED VIBRATION IN RATS EXPOSED TO BLAST INCREASED HISTOPATHOLOGY AND MODIFIED THE INFLAMMATORY RESPONSE
1Naval Medical Research Center, NeuroTrauma Department, Silver Spring, USA
2Henry M. Jackson Foundation for the Advancement of Military Medicine, Bethesda, USA
3Uniformed Services University of the Health Sciences, Department of Surgery, Bethesda, USA
4Walter Reed Army Institute of Research, Veterinary Services ‐ Diagnostic Pathology, Silver Spring, USA
5Walter Reed National Military Medical Center, Department of Surgery, Bethesda, USA
Keywords: Blast, TBI, Vibration, Inflammation
DELAYED XENON TREATMENT PREVENTS INJURY DEVELOPMENT FOLLOWING BLAST‐NEUROTRAUMA IN VITRO
Rita Campos‐Pires1,2,3, Amina Yonis1, Ashni Pau1, Warren Macdonald2,4, Katie Harris1, Nicholas Franks5, Christopher Edge5,6,
1Imperial College London, Surgery & Cancer, London, UK
2Imperial College London, Royal British Legion Centre for Blast Injury Studies, London, UK
3Charing Cross Hospital, Critical Care Medicine, London, UK
4Imperial College London, Bioengineering, London, UK
5Imperial College London, Life Sciences, London, UK
6Royal Berkshire Hospital, Anaesthetics, Reading, UK
Keywords: xenon, blast neurotrauma, blast traumatic brain injury, novel treatments
FUNCTIONAL IMPAIRMENT FOLLOWING DEPLOYMENT‐RELATED, BLAST‐ AND IMPACT‐INDUCED TBI AMONG ACTIVE DUTY ENLISTED MARINES
1Naval Health Research Center, Health and Behavioral Sciences, San Diego, USA
2Leidos, San Diego, USA
Keywords: blast, traumatic brain injury, functional impairment, military
BLAST‐INDUCED CHANGES IN CEREBRAL BLOOD FLOW AND VASCULAR REACTIVITY IN A RAT MODEL
1Naval Medical Research Center, Neurotrauma, Silver Spring, USA
2Henry Jackson Foundation, Neurotrauma, Bethesda, USA
3University of Maryland, Biology, College Park, USA
4Uniformed Services University of Health Sciences, Surgery, Bethesda, USA
5University of Virginia Medical Center, Radiology and Medical Imaging, Charlottesville, USA
Traumatic brain injury resulting from exposure to blast overpressure (BOP) is associated with cerebrovascular dysfunction which significantly influences the post‐injury outcome. This study examined blast‐induced changes in cerebral blood flow (CBF) and the effect of hypercapnia on CBF and vascular reactivity. Anesthetized rats were exposed to a single 130 kPa BOP in frontal orientation and were studied 2 hours (h) or 3 days after BOP exposure. Control animals were exposed to all procedures except BOP. To examine cerebrovascular reactivity, anesthetized rats (n = 7‐ 8/group) were mechanically ventilated and the pial microcirculation was visualized through a cranial window in the parietal bone using intravital microscopy. The reactivity of pial arterioles to hypercapnia was assessed by measuring vessel diameter before and after ventilation with 7% CO2 gas mixture. CBF monitoring (n = 6/group) in anesthetized rats was conducted using laser Doppler monitor for 2 h, during which the animals were exposed to 4 brief episodes of hypercapnia at 0.5 h intervals. Small‐sized arterioles (≤ 50 μm) did not show a difference in the CO2‐induced vasodilatory response (∼2‐4% increase) from control animals 2 h after blast; however, there was a significant increase (∼11%) in vasodilation 3 days after exposure. Medium‐sized arterioles (50‐100 μm) in all blast‐exposed rats showed diminished vasodilation (> 50% at 2 h and ∼80% at 3 days post‐blast) compared to control animals. CBF and hypercapnia‐induced increase in CBF were significantly reduced at 2 h but not at 3 days post‐blast in comparison to controls. The data suggest that exposure to blast impairs vascular regulatory mechanisms, which may contribute to the development of neurovascular pathology.
Keywords: cerebrovascular reactivity, vasodilation, intravital microscopy
1U.S. Naval Research Laboratory, Washington, DC, USA
2ASEE Postdoctoral Fellow at U.S. Naval Research Laboratory, Washington, DC, USA
3Walter Reed Institute of Research, Silver Spring, MD, USA
Exposure to low level blast overpressure is a common occurrence during military training exercises, particularly for disciplines such as breaching. While efforts are made to minimize the number of these exposures and limit them to ‘safe’ levels, there is still a paucity of information on how blast affects brain cells and how these effects scale with increasing overpressure exposure. We have designed a modular, gel‐based head surrogate system that has one brain module with pressure sensors and accelerometers, and another brain module capable of supporting primary murine neuronal cultures via the NRL cell pack. The cell pack is a sealed device that maintains 3D cell cultures for up to 2 weeks under sterile conditions, while allowing blast forces to penetrate the cell cultures. Both the instrumented and cellular modules are being exposed to a range of blast overpressures from low (considered safe) through high (expected to produce significant injury). Cellular response is being determined by changes in cell culture metabolism utilizing an MTT assay. Initial results show a significant decline in culture metabolism at the higher pressure ranges. Work is ongoing to establish the lower limit of the metabolic response. Disclaimer: Material has been reviewed by the Walter Reed Army Institute of Research. There is no objection to its presentation and/or publication. The opinions and assertions contained herein are the private views of the author, and are not to be construed as official, or as reflecting true views of the Departments of the Army, Navy, or Defense.
Keywords: Surrogate Brain, 3D Cell Culture, Blast Overpressure, Dose‐response
CHANGES IN CEREBRAL CORTICAL PROTEIN EXPRESSION IN A GYRENCEPHALIC ANIMAL MODEL AFTER A COMBINATION OF BRAIN INJURIES AND STRESS
USUHS, Anatomy, Physiology, & Genetics, Bethesda, USA
As the smallest mammal with a gyrencephalic cortex, ferrets have distinguishing features and demonstrate changes in protein expression after injury that are not seen in mice and rats. After blast exposure, we previously demonstrated increases in phosphorylated tau (ptau) as well as alterations in the ratio of the 3R and 4R isoforms of tau in specific regions of the cerebral cortex. Although blast injury is the hallmark of current conflicts, it usually occurs in the presence of stress and often coincides with other types of brain injuries. In this study we developed an animal model with a more realistic scenario of brain injury involving multiple blast exposures accompanied by rotational head injury (CHIMERA) and stress, delivered over a period of 2‐3 weeks. We included the following groups: Sham, Injury alone, Injury + Stress. After 4‐5 weeks post injury, each condition resulted in a different pattern of cortical expression of ptau and the tau isoforms 3R and 4R as measured using western blot. In general, the CHIMERA injury alone caused substantial increases in ptau in multiple cerebral cortical regions including the hippocampus, the prefrontal cortex, and the anterior cingulate; the blast injury resulted in increases in similar regions, but not as great. In a combination of CHIMERA and repetitive blast (including stress), the prefrontal cortex demonstrated the greatest increase in ptau and the 3R isoform, with smaller increases in other cortical areas. These alterations are mirrored by patterns of immunoreactivity against antibodies of the same forms of tau. Substantial changes in astrocytic immunoreactivity revealed by GFAP were present to different degrees in all conditions but the Sham. This model evaluates injuries that more closely reflect the events occurring in combat, while also producing outcomes similar to those that develop in people. Alterations in forms of tau suggest that this ferret model closely reflects histologic and chemical changes occurring after human injury. Supported by CNRM‐70‐8956.
Keywords: Model, Tau, inflammation, stress, repetitive, rotational head injury
EVALUATION OF THE ACUTE EFFECTS OF PRIMARY BLAST IN UNANESTHETIZED MALE AND FEMALE MICE
1Center for Neuroscience and Regenerative Medicine, Pre‐Clinical Studies Core, Bethesda, MD, USA
2Uniformed Services University of the Health Sciences, Department of Anatomy, Physiology and Genetics, Bethesda, MD, USA
Commonly used anesthetic drugs such as isoflurane are known to have neuroprotective properties, interfering with effects resulting from traumatic brain injury (TBI). For more accurate modeling of the clinical TBI condition, we need to understand the extent to which the use of anesthetics affect the functional and pathological outcomes following TBI in translational settings. In this study, unanesthetized and anesthetized (isoflurane) mice were restrained in plastic cones and placed in a prone position facing the oncoming blast overpressure wave (∼ 22 psi). Mice received four exposures to blast at 24‐hr intervals and were assessed daily for changes in weight and drinking behavior, nest shredding and building, and exploration in an open field (OF) environment. Unanesthetized mice did not lose consciousness from blast as evidenced by lack of a righting reflex, but the righting reflex was significantly longer than anesthetized sham controls in mice that received the combination of blast and isoflurane. Isoflurane reduced drinking behavior in sham‐treated male mice only. All mice, regardless of anesthesia or injury treatment, had poorer nesting behavior for the duration of the experiment. Exploratory behavior of female mice, but not male mice, was reduced in the OF by both anesthesia and blast exposure. There were no effects of either anesthesia or blast on anxiety‐like behaviors in the elevated zero maze the day following the final blast exposure. Immunohistochemical analysis (GFAP, Iba‐1, parvalbumin) is ongoing, but hematoxylin and eosin staining did not reveal gross pathological damage in the brain as a result of blast. In conclusion, the behavioral and pathological effects of multiple exposures to primary blast induced by the ABS are very mild, and there is no evidence to date of an acute neuroprotective effect of isoflurane in a translational blast model.
Keywords: parvalbumin, sex differences, isoflurane, anesthesia
DEVELOPMENT OF TACTILE ALLODYNIA AND ALTERED CGRP EXPRESSION FOLLOWING BLAST INDUCED MILD TRAUMATIC BRAIN INJURY IN MICE
1University of Iowa, Neurosurgery, Iowa City, USA
2University of Iowa, Molecular Physiology and Biophysics, Iowa City, USA
3University of Iowa, Neurology, Iowa City, USA
4Iowa VA Health Care System, Center for the Prevention and Treatment of Visual Loss, Iowa City, USA
Post‐traumatic headache (PTH) is a debilitating and common sequela of traumatic brain injury (TBI). PTH shares many of the same symptoms of chronic migraine. Calcitonin gene‐related peptide (CGRP) is a vasoactive neuropeptide that may mediate neurogenic inflammation and modulate nociceptive inputs related to PTH and migraine. This study aims to evaluate photosensitivity and tactile hypersensitivity in a mouse model of mild, blast induced TBI, with subsequent assessment of CGRP RNA expression in the cerebral cortex and the trigeminal ganglia by real‐time polymerase chain reaction. This model of TBI is not able to induce photophobia as assessed by light‐aversion assay. However, injured mice develop tactile hypersensitivity. Both cephalic and extra‐cephalic allodynia is seen starting 1 week after the injury and persisting for at least 9 weeks. Expression of CGRP in the cerebral cortex and trigeminal ganglia 1‐week post‐injury is altered compared to uninjured control animals. This is the first report of the development of a chronic pain phenotype following mild TBI in mice with corresponding alterations in CGRP expression. The high incidence and chronic nature of PTH underscores the importance of studying this problem in animal models in order to develop new and effective treatments. Additional work is necessary in order to further characterize these behavioral models, and the alterations in CGRP expression as they relate to PTH.
Support: Dept. Defense W81XWH‐16‐1‐0071, W81XWH‐16‐1‐0211; VA‐ORD (RR&D) 1IO1RX002101 and C6810‐C.
Keywords: CGRP, Post‐traumatic headache, Mild TBI, Blast injury, Neurogenic inflammation
PRIMARY LOW‐INTENSITY BLAST: ENERGY PARAMETERS INDUCE ULTRASTRUCTURAL, MITOCHONDRIAL, AND ASSOCIATED NEUROBEHAVIORAL ABNORMALITIES
1U of Missouri, Columbia, USA
2VA, Washington, DC, USA
3Bedford VA, Bedford, USA
4TrumanVA, Columbia, USA
5STARR‐C, Philadelphia, USA
The majority of military‐related neurotraumas with many by explosive weaponry are mild TBI, considered “invisible” injuries. While prior studies have investigated moderate to severe brain injuries, the mechanisms of low‐intensity blast (LIB)‐mediated pathobiology and subsequent neurological deficits remain unclear. We established a militarily relevant LIB injury model in mice by open‐field detonation of 350‐gram C4. We report new measures of primary and ground‐reflected shockwaves, generating 46.7‐kPa static peak overpressure with 409 and 388 m/s primary shockwave and ground reflection velocities respectively, 60 kPa x ms maximal impulse, without visible impact/acceleration from the 3‐m blast exposure. LIB caused multifaceted ultrastructural abnormalities including myelinated axonal injuries, synaptic alterations, and mitochondrial abnormalities in the absence of apparent cellular damage at 7‐ and 30‐days post injury. Neurobehavioral abnormalities included reduced exploratory activities, elevated anxiety‐like levels, impaired nesting behavior, and compromised spatial reference learning and memory. Quantitative proteomics showed mitochondrial dysfunctional pathways associated with elevated oxidative stress, impaired fission‐fusion dynamics, diminished mitophagy, decreased oxidative phosphorylation, and compensated respiratory chain enzyme activity at these levels of overpressure and shockwave velocity. Findings of elevated total tau and phosphorylated tau, and Aβ levels after LIB suggest possible links to neurodegeneration requiring further studies of chronic responses. Clearly a single LIB exposure causes ultrastructural brain injury and neurobehavioral changes in this murine model. These studies provide an understanding of open‐field energy impacts including energy from shockwave velocity. This militarily relevant blast model can be used for future comparative studies of brain injury including repetitive blasts and longitudinal effects. Quantitative comparisons of open‐field blast energies to other models of brain injury including blast tube and impact/acceleration are needed to fill gaps in our knowledge of the spectrum of blast injury effects.
Keywords: open‐field low‐intensity blast, axonal injury, tau, mitochondrial dysfunction, transmission electron microscopy, synaptic alterations, behavioral abnormalities, shockwave velocity
BLAST‐MEDIATED TRAUMATIC BRAIN INJURY EXACERBATES RETINAL DAMAGE AND AMYLOIDOSIS IN THE APPSWEPSEND19E MOUSE MODEL OF ALZHEIMER'S
1University of Pittsburgh, Neurology, Pittsburgh, USA
2University of Pittsburgh, Psychiatry, Pittsburgh, USA
3Pittsburgh VA Healthcare System, Geriatric Research Education and Clinical Center, Pittsburgh, USA
4University of Iowa, Ophthalmology and Visual Sciences, Iowa City, USA
5Iowa City VA, Center for the Prevention and Treatment of Visual Loss, Iowa City, USA
Keywords: blast, amyloid, retina, optic nerve, Alzheimer's
A3 ADENOSINE RECEPTOR (A3AR) AGONIST, AST‐004, IS NEUROPROTECTIVE IN BLUNT AND BLAST MODELS OF TRAUMATIC BRAIN INJURY (TBI)
1University of Texas Health Science Center at San Antonio, San Antonio, USA
2U.S. Army Institute of Surgical Research, Fort Sam Houston, San Antonio, USA
3Applied Research Associates, San Antonio, USA
4Astrocyte Pharmaceuticals Inc., Cambridge, USA
TBI is a risk factor for the development of seizures and behavioral changes. Here, we test the hypothesis that treatment with A3AR agonist AST‐004 reduces post‐traumatic seizures and moderates or prevents deleterious effects associated with TBI. Using both blunt and blast TBI models, we pharmacologically treated mice with AST‐004 (i.p. 0.2 mg/kg, provided by Astrocyte Pharmaceuticals) or vehicle 30 minutes after injury. Twenty‐four hours later, spontaneous seizures were monitored by EEG/video recording in blast TBI. An independent cohort of mice were sacrificed 3 days after blunt TBI, and cell death and blood brain barrier (BBB) permeability changes were quantified. A third cohort of animals were sacrificed 7 days after both TBI models and used for RT‐qPCR and IHC analyses of GFAP and IBA‐1, markers of astrocyte and microglial activation, respectively. Finally, memory test responses were assessed in both TBI models. After blast TBI, 50% of vehicle only‐treated mice displayed spontaneous seizures. AST‐004 decreased seizure frequency (28%). Contextual memory impairment was observed in blunt TBI but not in blast TBI. This behavioral phenotype was inhibited by AST‐004. Cell death, BBB disruption and glial activation were reduced after AST‐004 in blunt TBI. The findings presented here indicate that blast TBIs cause early seizures. Memory dysfunction, cell death and BBB disruption were prominent mechanisms in blunt injuries. Pharmacological treatment by A3AR agonist AST‐004 substantially protected against blunt and blast TBI induced deficits. Future studies are needed to clarify the role of A3AR in TBI pathogenesis and the potential of AST‐004 in clinical trials. Supported by DoD CDMRP grants W81XWH‐15‐1‐0284 (M.S.S. and R.B.), W81XWH‐15‐1‐0283 (J.D.L.), and by Astrocyte Pharmaceuticals (J.D.L., W.K., and T.L.).
Keywords: TBI, A3AR, Seizure, Cell death, BBB
NITRIC OXIDE SYNTHASE MEDIATES CEREBELLAR DYSFUNCTION IN MICE EXPOSED TO REPETITIVE BLAST‐INDUCED MILD TRAUMATIC BRAIN INJURY
1University of Washington, Medicine, Seattle, USA
2Veterans Affairs, Research, Seattle, USA
Repetitive blast‐induced mild traumatic brain injury (mTBI) is associated with delayed blood‐brain barrier (BBB) dysfunction and persistent neurological sequelae. We and others have shown that both the human and mouse cerebellum are particularly vulnerable to the negative consequences of blast forces. We have also found that nitric oxide synthase (NOS) inhibition with N(G)‐nitro‐L‐arginine methyl ester (L‐NAME) can attenuate delayed BBB disruption in mice exposed to repetitive blast mTBI. Therefore, we investigated whether cerebellar‐specific neurological sequelae would persist after L‐NAME attenuation of blast‐induced BBB dysfunction. At 72 hours following mTBI, we find in the cerebellum demonstrable BBB disruption as evidenced by 99mTc‐albumin permeability. In association with albumin permeability, we also found elevated intercellular adhesion molecule 1 (ICAM1) expression, and CD4+ T‐cell infiltration. LNAME administration mitigated both albumin permeability and CD4+ T‐cell infiltration in the cerebellum. These results suggest that blast mTBI can induce NOS‐dependent immune cell infiltration that could be associated with persistent cerebellar dysfunction. As such, we then examined the effects of LNAME administration on sensorimotor performance and cerebellar neuropathology at one month after repetitive blast. We observed persistent sensorimotor deficits and aberrant dendritic arborization in mice exposed to repetitive blast mTBI. L‐NAME improved sensorimotor performance, but aberrant cerebellar pathology did persist. These results suggest that NOS‐dependent BBB dysfunction occurring days after repetitive blast mTBI may be associated with persistent sensorimotor deficits, but may not reflect the inevitable consequence of aberrant cerebellar pathology. Overall, we present clear evidence of NOS‐dependent cerebellar dysfunction in mice exposed to repetitive blast mTBI. From these data, we encourage future studies to focus on the specific vulnerability of the cerebellum to blast forces when considering therapeutic options for repetitive mTBI.
Keywords: Blast, Blood‐brain barrier, Cerebellum, T‐cell
ANTI‐LYSOPHOSPHATIDIC ACID ANTIBODIES PROTECT AGAINST BLAST‐INDUCED OCULAR DYSFUNCTIONS
1Walter Reed Army Institute, Blast‐Induced Neurotrauma, Silver Spring, USA
2University of Kentucky, College of Medicine, Lexington, USA
3San Diego State University, Department of Biology, San Diego, USA
Exposure to blast has been implicated as major cause of ocular injuries and resultant visual dysfunctions in combat operations, but no effective countermeasure has been developed thus far. Lysophosphatidic acid (LPA) is a bioactive lysophospholipid released from platelets, astrocytes, choroidal plexus cells and microglia and play major roles in activating inflammatory processes. Acute increases in LPA levels were observed in the cerebrospinal fluid (CSF) and plasma of patients after TBI and use of antibodies against LPA was found to be protective against TBI and neuropathic pain in animal models. Since in preliminary studies we observed acute increases in LPA levels in the CSF and plasma of rats after blast exposure, we have evaluated efficacy of anti‐LPA antibodies for protection against blast‐induced ocular injuries. Single intravenous injection of anti‐LPA antibodies (25 mg/kg) was given to rats 1 hr after single blast exposure using advanced blast simulator, and ocular functions and retinal pathology were evaluated at different intervals. Visual acuity tests by optokinetics were carried out post‐blast on days 2 & 6, electroretinography (ERG) was conducted on days 3 & 7 and retinal pathological evaluations were performed on day 8. H&E staining revealed significant protection against neuronal cell deformation in the retinal photoreceptor and outer nuclear layers after treatment. Immunohistochemical evaluations indicated that the antibody treatment decreased the presence of both activated astrocytes and microglia in the retina. Antibody treatment improved visual acuity in both eyes. ERG showed significant improvements in both A & B waveform amplitudes in the left eyes and B waveform amplitude in the right eyes on day 7. Our data reveals that LPA plays an important role in ocular injuries following blast and early intervention with anti‐LPA antibodies provide protection against damages to the retina.
Keywords: Vision, Ocular injury, Eye injury
NEUROCOGNITIVE PERFORMANCE DEFICITS RELATED TO IMMEDIATE AND ACUTE BLAST OVERPRESSURE EXPOSURE
1Oak Ridge Institute for Science and Education, Oak Ridge, USA
2Walter Reed Army Institute of Research, Silver Spring, USA
3University of Florida, Gainesville, USA
Sub‐concussive effects following exposures to explosive blast remain a subject of ongoing research. This report details neurocognitive performance assessments from 2 years of observations. As research matures and data accrue, findings identify small, transient, undiagnosed, blast‐related effects in an otherwise healthy population. In previous reporting, exposure to low level explosive blast yielded difficulty in concentration and memory. We used the Defense Automated Neurobehavioral Assessment (DANA) Rapid across 7 military training courses involving exposure to explosive blast. The 5‐minute DANA Rapid was administered to 202 healthy, male, military volunteer participants immediately (within 5 minutes) after back‐to‐back explosive charges and at end of day (25 minutes to 2 hours after exposure). Individually‐worn pressure transducers showed service member exposures with an average incident overpressure of 4.6 pounds per square inch (psi) (range: 2.57 psi ‐ 9.17 psi). Mixed‐effects models of DANA performance change from baseline included covariates and blast characteristics. Of 3 subtests in DANA Rapid, Procedural Reaction Time (PRT) showed the clearest evidence for the hypothesized effect, with mixed effects model estimate of 10.51 (95% CI: 3.33, 17.68). Multiple regression estimates showed the overpressure effect in both Immediate [9.17 (95% CI: 0.39, 17.94)] and Acute [13.61 (95% CI: 4.97, 22.26)]. PRT was likely the most sensitive subtest due to the burden the task places on working memory and maintenance of cognitive sets, consistent with other results in this population. The specific finding, a reduced level of expected improvement when exposed to higher levels of blast overpressure, is a pattern previously observed in reduced practice effects among concussion cases in U.S. Military Academy boxing. Behavioral assessment augments our study of blood‐based neurotrauma biomarkers associated with blast exposure. Performance impairment, along with biological markers and symptom reporting, will enable the DoD to refine safety protocols for the use of explosives.
Keywords: military, overpressure, behavioral, sub‐concussive
OMEGA‐3 FATTY ACID DEFICIENCY INCREASES NEUROLOGICAL IMPAIRMENTS IN A RAT MODEL OF COMBINED BLAST‐TBI AND TRAUMATIC STRESS
Walter Reed Army Institute of Research, Blast‐Induced Neurotrauma Branch, Silver Spring, USA
US Soldiers suffer a high incidence of traumatic brain injuries from bomb explosions (blast‐TBI). There is a high co‐morbidity of blast‐TBI with post‐traumatic stress disorder (PTSD) development. Dietary long chain omega‐3 polyunsaturated fatty acids (omega‐3s) are building blocks of neuronal cell membranes and are converted to anti‐inflammatory metabolites. Omega‐3 deficiency is a risk factor for cognitive and psychiatric disorders. Providing dietary omega‐3s improves outcomes in many models of brain trauma. Thus, we explored if an omega‐3 poor diet increases vulnerability to blast‐TBI and PTSD, and if combining these insults has an additive deleterious effect. Adult male rats were maintained for 6 weeks on diets devoid of omega‐3s and increased in pro‐inflammatory omega‐6 content. Anesthetized animals were then exposed once to a simulated blast over pressure wave (18 psi) followed by a weight drop skull concussion (500 g from 125 cm), to induce TBI symptoms. After 3 days of recovery, the rats were subjected once to a traumatic stressor, i.e., forced immersion underwater (30 sec), to induce “PTSD” behaviors. Shams were subjected to anesthesia and free swimming. Diets were continued and the animal's neurobehavioral function was evaluated out to 28 days, using rotarod, rotary pole, elevated plus maze, Y‐maze, and open field tests. Our results showed that blast‐TBI plus traumatic stress leads to minor increases in behavioral impairments, compared to each insult alone, e.g. coordination, “anxiety”, and hyperactivity disturbances. Omega‐3 deprivation, however, markedly perturbed the behaviors of both shams and injured rats. Our findings, in showing little impact of combining the insults, may indicate that their underlying pathophysiological processes can mask each other. Nevertheless, omega‐3 deficiency caused a worsening of the outcomes. Our future studies will examine the cellular and biochemical status of the brains. Supported by a DoD grant from the USAMRMC / MOMRP.
Keywords: Rat, Blast wave, Brain, Neurotrauma, Traumatic stress, Omega‐3 polyunsaturated fatty acid
REPEATED BLAST OVERPRESSURE EXPOSURE LEADS TO ENDOVASCULAR DISRUPTION AND ALTERATIONS IN TDP‐43 AND PIEZO2
1Walter Reed Army Institute of Research, Silver Spring, USA
2Naval Medical Research Center, Silver Spring, USA
Repetitive exposure to primary blast may cause cumulative impairment, with progressive vascular and cellular changes. The mechanical force associated with blast exposure can cause deleterious cellular perturbations in the brain, leading to secondary injury and potential neurodegeneration. To better appreciate the cumulative effects of repetitive blast on the brain, an advanced blast simulator (ABS) was used to closely mimic “free‐field” blast. Rats were exposed to 1‐4 daily blasts at 13 psi peak incident pressures with a positive duration of 3‐4 msec, either in a transverse (sideways) or longitudinal (front facing) orientation. Vascular endothelial growth factor (VEGF), tight‐junction proteins (occludin, and claudin‐5), the mechanosensitive channel receptor (piezo2), and transactive response DNA binding protein 43 kDa (TDP‐43) were measured following blast exposure. TDP‐43 is tightly regulated and altered expression of TDP‐43 was found following TBI and in neurodegenerative diseases such as frontotemporal dementia (FTD). TDP‐43 levels were significantly decreased after 2x13psi exposures, but rats exposed to 1, 3, or 4 blasts did not show any change in TDP‐43. Piezo2, a mechanosensitive channel, has been shown to be dysregulated following blast and was here observed to significantly decrease after 1, 3 or 4x13psi exposures, but increase after 2 exposures, indicating that blast may cause a change in sensitivity to mechanical stimuli in the brain, which could contribute to cellular injury. Lastly, changes in expression of claudin‐5 (decreased after 2x13psi(front); increased after 1x13(front), 3x13(front), and 2x13(side)), occludin (decreased after 3x13psi(side); increased after 2x13(side) and 4x13(side)), and VEGF (increased after 1x13 and 2x13psi) after repeated blast exposure indicate alterations in the BBB and are orientation‐dependent. These findings reveal that cumulative effects of repeated exposures result in complex biochemical changes that point to unique dynamics associated with repetitive blast that may have implications for long‐term outcomes.
Keywords: Blast‐induced TBI, TDP‐43, Repetitive blast
ACOUSTIC AND BLAST OVERPRESSURE EXPOSURE IN A MILITARY TRAINING ENVIRONMENT
Walter Reed Army Institute of Research, Blast Induced Neurotrauma Branch, Silver Spring, USA
Breacher's Brain (BB) is a constellation of symptoms including trouble sleeping, memory issues, tinnitus, and short‐term neurocognitive detriment. Over the last decade, investigations have focused primarily on peak blast OP exposure and impulse as the likely causal mechanisms for any observed detriments. In response to complaints of BB symptoms from grenade range instructors an OP evaluation was conducted. Results documented little OP and a follow on study included acoustic measures. This presentation documents the acoustic and OP exposure associated with a simple environment (grenade range instructors) and in a much more complex close quarters training (CQT) environment.
Keywords: acoustic blast exposure, occupational blast exposure, occupational acoustic exposure
EVIDENCE OF DIRECT BIOMECHANICAL LOADING ON BRAIN FOLLOWING PRIMARY BLAST EXPOSURE
1Walter Reed Army Institute of Research, Blast Induced Neurotrauma, Silver Spring, USA
2Telemedicine and Advanced Technology Research Center, Biotechnology High Performance Computing Software Applications Institute, Fredetick, USA
3The Henry M. Jackson Foundation for the Advancement of Military Medicine, Inc, Bethesda, USA
Several biomechanical mechanisms have been proposed to account for primary blast injury to the brain including direct and indirect (e.g. thoracic) transmission of overpressure. The objective of the current study is to establish the role of direct mechanism(s) using a rodent model of blast exposure. For biomechanical studies, anesthetized male Sprague Dawley rats were surgically probed with intracranial (lateral ventricle and epidural) and intravascular (carotid and femoral) pressure transducers. An advanced blast simulator (ABS) that closely mimics “free‐field” blast was used to expose animals (n = 8/group) to blast at ∼130, 100 or 70 KPa in a vertical whole‐body (WB) or in a head‐only (HO) orientation; in the latter circumstance, blast exposure was restricted to the head which was securely immobilized/fixed within the ABS. For parallel neuropathological assessments, rats (n = 8/group) were exposed to blast at ∼130 KPa in HO or WB orientations using GFAP immunohistochemistry to quantitate astrogliosis, while sham animals underwent identical handling with the exception of blast exposure. Intracranial pressure responses to blast were similar across exposures in either the WB or HO orientation, while, unlike responses seen with the WB orientation, carotid and femoral pressure responses to blast were negligible in the HO orientation, revealing loading of the brain in the absence of thoracic exposure. GFAP staining for brain astrogliosis revealed near‐identical changes in the HO and WB orientations, which were greater (p < 0.05) than astrogliosis in shams at 24‐hours and 14‐days following blast. In conclusion, these findings reveal that direct loading of blast to the head can cause robust changes in brain even in the absence of thoracic exposure transmission.
Keywords: Biomechanics, Intracranial pressure, Pathology
A06 Cognition / Learning / Memory
DAILY CONTEXTUAL MANIPULATIONS ARE NECESSARY FOR SUCCESSFUL COGNITIVE REHABILITATION FOLLOWING EXPERIMENTAL TBI
1Barrow Neurological Institute at Phoenix Children's Hospital, Translational Neurotrauma, Phoenix, USA
2University of Arizona, COM‐Phoenix, Child Health, Phoenix, USA
Traumatic brain injury (TBI) is not a transient event from which all people recover; the resulting damage can evolve into neurological disease. As with patients, experimental TBI disrupts rodent memory circuits, evident as impaired cognitive performance. Experimental rehabilitation strategies, such as enriched environment and exercise, have partial success in alleviating symptoms. New rehabilitation strategies are necessary to demonstrate therapeutic efficacy and explore cellular mechanisms that promote recovery. Diffuse brain injury by midline fluid percussion leads to cognitive impairments by 1 month post‐injury, permitting a timeframe to implement and investigate delayed interventions. Rehabilitation occurs in a box with a peg‐board floor that allows for 10cm plastic pegs to be inserted at 2.5cm intervals in designated layouts; termed Peg Forest Rehabilitation (PFR). Brain‐injured rats were exposed to PFR (15 min/day), allowing free navigation through either random daily layouts or the same layout daily in the peg‐filled arena for 10 days over 2 weeks. The current study compared random daily PFR (dynamic) arrangements versus the same PFR (static) arrangement for two weeks in male and female brain injured rats. We hypothesized that dynamic daily arrangements, not static, are necessary to prevent the onset of injury‐induced memory impairments by challenging the limbic memory circuit. Previous results show that 2 weeks of PFR prevents the onset of cognitive deficits in short‐term, long‐term, and working memory. Preliminary data revealed no differences between males and females, so they were combined for analyses. As previously shown, brain injured rats exposed to the dynamic PFR did not exhibit any deficits on 3 cognitive assessments. Interestingly, rats exposed to the static PFR were significantly impaired when compared to the dynamic PFR rats. Thus, passive, dynamic, intermittent rehabilitation targeting specific circuitry can prevent cognitive symptomatology. The Peg Forest is a viable rehabilitation strategy to explore cellular and molecular mechanisms to preserve neurological function.
Keywords: Cognitive rehailitation, Diffuse traumatic brain injury
TRAUMATIC BRAIN INJURY IS ASSOCIATED WITH PROGRESSIVE BRAIN VOLUME LOSS
1Henry Jackson Foundation, Bethesda, USA
2Center for Neuroscience and Regenerative Medicine, Bethesda, USA
3National Institutes of Health, Bethesda, USA
4Uniformed Service University of Health Science, Bethesda, USA
Assess changes in brain volumes attention/processing speed, executive functioning, language, working memory, and delayed memory up to five years after TBI.
A prospective study of patients with mild, moderate or severe TBI, enrolled at the Clinical Center, National Institutes of Health, Bethesda, MD, USA. 185 (165 TBI, 20 healthy) participants enrolled; 110 underwent repeated MRI and outcome assessment at one or more time points after injury: 30 (n = 30), 90 (n = 48), 180 (n = 59) days, and 1 (n = 82), 2 (n = 57), 3 (n = 46), 4 (n = 38), 5 (n = 29) years. Brain structure was assessed using summary measures from FreeSurfer‐based regions of interest on T1‐weighted MRI scans. Composite scores for domains of attention/processing speed, executive functioning, language, working memory, and delayed memory in patients with valid test data. Generalized mixed‐effects models with random intercepts and slopes, adjusted for age, education, and gender were constructed for assessing longitudinal changes in brain volumes and neuropsychological composite scores.
The estimated change per year in brain volume relative to group baseline average was pronounced (−1% to ‐6%) in the corpus callosum, thalamus, accumbens area, and cerebellum white matter. Neuropsychological composite scores showed significant improvements in all measured domains except for language and working memory.
These results suggest that TBI results in loss of brain volume, which continues for many years after injury, especially moderate‐severe cases. Brain volume loss is more pronounced in white matter and positively related to injury severity. Conversely, TBI patients showed improvement or recovery in attention/processing speed, executive functioning, language, and delayed working memory domains despite progressive volume loss, suggestive of two separate processes, at least in this cohort of patient with follow‐up time of five years.
Keywords: TBI, Volume, Prospective, Neuropsychological
XENON PREVENTS NEURODEGENERATION AND LATE‐ONSET COGNITIVE IMPAIRMENT, AND IMPROVES SURVIVAL AFTER TRAUMATIC BRAIN INJURY IN MICE
1Imperial College London, Surgery and Cancer, London, United Kingdom
2Imperial College London, Royal British Legion Centre for Blast Injury Studies, London, United Kingdom
3Charing Cross Hospital, Critical Care Medicine, London, United Kingdom
4Johannes Gutenberg University, Anesthesiology, Mainz, Germany
5Johannes Gutenberg University, Mouse Behavioural Outcome Unit, Mainz, Germany
6Imperial College London, Life Sciences, London, United Kingdom
7Royal Berkshire Hospital, Anaesthetics, Reading, United Kingdom
Keywords: xenon, neuroprotection, controlled cortical impact model, neurodegeneration
ASSOCIATION BETWEEN INTRINSIC NETWORK PROPERTIES AND COGNITIVE FUNCTION AFTER MILD TRAUMATIC BRAIN INJURY
Seoul National University Hospital, Seoul, Korea South
Brain imaging data was preprocessed using the FSL (v6.0.1). Brain signal of the 116 regions of interest (ROIs) was extracted from the preprocessed and bandpass filtered data. Positive correlation matrix was constructed and thresholded considering the sparsity of the matrix (the number of edges was the same between individuals, the size of the connected components was the largest). Betweenness centrality (BC) and local efficiency (Eloc) were estimated. Spearmans' correlation coefficient between the sub‐scores of CNT test and BC or Eloc was estimated with controlling for age in each group. Statistical significance was set at P < 0.001.
In control group, for BC, negative correlation was observed in the right middle temporal pole with visual learning test A5 (r = −0.941). For Eloc, the left middle frontal area and forward digit span test was positively correlated (r = 0.959), while the left middle occipital area and visual learning test A5 was negatively correlated (r = −0.944).
Keywords: Neuroimaging, Resting state functional connectivity, Graph theory
THE EFFECT OF AMANTADINE ON FUNCTIONAL RECOVERY AFTER TRAUMATIC BRAIN INJURY: A SYSTEMATIC REVIEW AND META‐ANALYSIS
Seoul National University Hospital, Neurosurgery, Seoul, Korea South
Many studies investigated the efficacy of amantadine in the functional recovery in traumatic brain injury. We performed a systematic review and meta‐analysis to evaluate the effect of amantadine to improve cognitive and behavioral performances of the patients with traumatic brain injury. Randomized controlled trials and retrospective cohort studies were searched through Pubmed, Embase, Web of Science, and the Cochrane Library according to PRISMA protocol. Study selection was performed by two independent reviewers. 20 studies met inclusion criteria: 11 randomized controlled trials and 9 retrospective studies. Using a random effect model, meta‐analysis was performed to estimate the effect on cognitive function and agitation/aggression. MMSE, DRS, GOS, FOUR score and FIM‐cog were used as scales of cognitive function and NPI‐I and NPI‐A were used as scales of agitation/aggression. Risk of a bias was evaluated using funnel plot. The results from this study suggest that amantadine may accelerate recovering cognitive defect after traumatic brain injury, but there was no significant effect on reducing agitation/aggression.
Keywords: amantadine, cognition, agitation, aggression, systematic review and meta‐analysis, traumatic brain injury
DUAL ALLOSTERIC MODULATION: A NOVEL STRATEGY TO REVERSE TRAUMATIC BRAIN INJURY‐INDUCED COGNITIVE IMPAIRMENTS
1University of Miami Miller School of Medicine, Neurological Surgery, Miami, USA
2School of Medicine, University of California, Pharmacology, Irvine, USA
Traumatic brain injury (TBI) significantly impairs cognitive functioning and in particular, learning and memory in chronic survivors. Thus, therapeutics to treat chronic learning and memory deficits after TBI are greatly needed. α5 subunit‐containing GABAA receptors (GABAARs) and α7 nicotinic acetylcholine receptors (nAChRs) are important mediators of cognition. A dual action compound 522‐054, which is an allosteric modulator acting simultaneously on both the α7 nAChR and GABAAR induces long‐term potentiation (LTP) and enhances cognitive functioning in normal animals. We hypothesized that modulating both the α7 nAChRs and GABAARs simultaneously with the allosteric modulator 522‐054 would enhance cognitive functioning in the chronic recovery period of TBI. To test this hypothesis, adult male Sprague Dawley rats received moderate parasagittal fluid‐percussion brain injury or sham surgery. At 3 months after recovery, animals received vehicle or drug 522‐054 (0.03 mg/kg, intraperitoneally) at 30 minutes prior to training on fear conditioning and the water maze. TBI significantly impaired cue and contextual fear conditioning as well as water maze acquisition and retention. Treatment with 522‐054 during training on both of these tasks reduced deficits in cue and contextual fear memory and water maze acquisition and retention. We further assessed the effects of 522‐054 on basal synaptic transmission and long‐term potentiation (LTP) in area CA1 of the hippocampus at 3 months after TBI. There was a significant reduction in basal synaptic transmission and expression of LTP in slices from TBI animals as compared to sham animals. Bath application of 522‐054 (0.1 μM) reversed the deficits in basal synaptic transmission and LTP expression. Our results demonstrate that 522‐054 improves hippocampal synaptic plasticity and cognitive performance after TBI in the chronic recovery period. These finding suggest that simultaneous modulation of cholinergic and GABAergic transmission through a dual allosteric modulator may be a novel therapeutic route to improve cognition after TBI.
Keywords: Traumatic Brain Injury, Positive Allosteric Modulation, Synaptic Plasticity
CEREBRAL PERFUSION AND POSTCONCUSSIVE SYMPTOM REDUCTION AFTER COGNITIVE TRAINING IN CHRONIC MMTBI PATIENTS
University of New Mexico, Psychiatry, Santa Fe, USA
Keywords: mild traumatic brain injury, brain stimulation, cognitive training, cerebral blood flow
COGNITIVE IMPAIRMENT, PSYCHOLOGICAL HEALTH AND FUNCTIONAL STATUS AFTER TBI: A TEAM‐TBI STUDY
University of Pittsburgh, Pittsburgh, USA
Keywords: psychological health
A COMPARATIVE STUDY OF THERAPEUTIC EFFECTS OF MANNITOL AND HYPERTONIC SALINE FOR SEVERE TRAUMATIC BRAIN INJURY IN RATS
Zachary Kiernan, Andrew Rolfe, Alex Valadka,
Virginia Commonwealth Univ., Anatomy and Neurobiology, Richmond, USA
Severe TBI is often associated with elevated intracranial pressure (ICP). Hyperosmolar agents, such as hypertonic saline (HTS) and mannitol, are commonly used to reduce ICP. Historically, 20% mannitol is considered the “gold standard”; however, the use of HTS in various concentrations has grown. While both are effective at lowering ICP, it remains unclear as to whether one is superior and what concentration is most effective. Additionally, there is a paucity of data examining their long‐term neuroprotective effects. Using direct ICP measurement and behavioral testing, this study investigated the effects of HTS and mannitol at the acute and chronic phases in rats after a severe lateral fluid percussion injury (LFPI). Adult male Sprague‐Dawley rats received a LFPI at the level of 2.3ATM and followed by i.v. infusion of 1.2ml of 7.2% HTS or 20% mannitol at 30 minutes after injury. For the acute phase study, ICP was monitored for 4‐hr via an intra‐parenchymal ICP probe. Physiologic and biochemical parameters as well as brain water content were measured. For chronic study, a separate cohort of animals underwent a battery of behavioral tests over two weeks to examine motor and cognitive functions, and their brains were harvested for histological analysis to identify the extent of neuronal degeneration and inflammation. We have found a marked decrease in ICP following injury in both HTS and mannitol treated groups. However, we did not find significant group difference in brain water content, physiological and biochemical parameters. We also failed to find significant improvement in both motor and cognitive functions in the mannitoal or HTS treated groups. Our data suggest that while hyperosmolar treatment is effective in lowering ICP, it may not have a significant long‐term effect on neurocognitive functional recovery. The histological examination assessing hyperosmolar agents on cellular changes in the injure brain is ongoing. Supported by Virginia Neurotrauma Initiative Trust Fund (A262‐76756).
Keywords: ICP, hyperosmolar treatment, cognitive function,
THE EFFECTS OF FATIGUE AND SLEEP ON NEUROCOGNITIVE PERFORMANCE AND CONCUSSION SYMPTOM REPORTING
1Walter Reed Army Institute of Research, Center for Military Psychiatry and Neurosciences, Silver Spring, USA
2Fordham University, Computer and Information Science Department, Bronx, USA
3U.S. Air Force Academy, Behavioral Sciences & Leadership, USAF Academy, USA
Neurocognitive assessments are ubiquitous in concussion care. They provide a baseline measure of performance that is useful when combined with other assessment techniques to evaluate post‐concussion recovery. Neurocognitive assessments are collected in a controlled environment, and detailed administration guidelines are provided. These guidelines tend to focus on computing software and hard requirements as well as environmental factors (e.g., a quiet room), and less on the physiological state of the athlete. At [redacted], we administered a neurocognitive baseline assessment to the entire incoming class of basic cadets, specifically, the Immediate Post‐Concussion Assessment and Cognitive Testing (ImPACT). [redacted] is a military academy, and a scheduling conflict required that the basic cadets took their neurocognitive assessment in a fatigued and sleep‐deprived state. The following year, we re‐administered a neurocognitive baseline assessment to the same class of cadets when they were rested. Thus, there was an opportunity for a natural pretest/posttest experiment with a large sample size (N = 1,142). It was predicted that cadets that are fatigued/sleep‐deprived would perform worse when compared to their rested performance. Further, we predicted, that fatigued/sleep‐deprived cadets would report more symptoms. As expected, performance declined for all measures indicating a pervasive effect of fatigue/sleep‐deprivation on memory, attention, processing, learning, reaction time, and inhibition. Regarding concussion symptoms, principal component analysis revealed trends in reporting across symptoms. The first component captured over 30% of variance in reporting, finding strong connections among reporting of difficulty concentrating, sensitivity to light, and numbness; with much weaker connections to fatigue and nausea. Thus, constellations of symptoms may correlate with low sleep, even beyond those directly related to sleep. In summary, when performing a concussion baseline or post‐concussion assessment, the physiological state of the athlete should be taken into account.
Keywords: Concussion, Concussion baseline assessment, Neurocognitive testing
REPEAT CLOSED‐HEAD INJURY IMPAIRS ATTENTION, BUT NOT IMPULSIVITY IN RATS
West Virginia University, Psychology, Morgantown, USA
Traumatic brain injury (TBI) is associated with the development of various neuropsychiatric disorders. Specifically, individuals that experience TBIs are at higher risk for developing deficits in impulsivity and decision‐making. Although the majority of clinical TBI cases reported are classified as mild, research regarding the effects of mild brain injury in animal models is relatively limited. The current study evaluated the effects of repeated closed head injuries using the Closed Head Impact Model of Engineered Rotational Acceleration (CHIMERA) system on impulsive choice, attention, and motor impulsivity in rats. The delay discounting task (DDT) was used to measure choice impulsivity and the five‐choice serial reaction time task (5CSRT) was used to measure attention and motor impulsivity. Rats were trained daily on each task until stable baselines were established (∼70 sessions). Following baseline, CHIMERA injuries were delivered once per week for five weeks with a 100g, 5‐mm impact tip centered in front of bregma, delivered at 7 m/s. Rats were assessed five times per week on the tasks during the 5‐week injury period and a 4‐week recovery period. Substantial deficits in attention emerged, while motor and choice impulsivity were relatively unaffected. These results stand in contrast to prior research in the same model, suggesting that further investigation of the parameters of, and mechanism by which concussive‐like injuries cause behavioral symptoms is warranted.
Keywords: Attention, Impulsivity, Closed‐Head Injury, Repeat Injury
FRONTAL TRAUMATIC BRAIN INJURY REDUCES SENSITIVITY TO CUES AND CONDITIONED REINFORCERS
West Virginia University, Psychology Department, Morgantown, USA
Traumatic Brain Injuries (TBI's) continue to be a growing concern that often result in cognitive deficits such as increased impulsivity and risky decision‐making. While research has been quick to illustrate the presence of impulsivity and risky behaviors, understanding sensitivity to cues that may predict reinforcers is limited. Evaluating goal‐ and sign‐tracking behaviors has been a supported paradigm that effectively predicts sensitivity to cues, however this measure is typically used in addiction models. The current study utilizes this paradigm and other measures of conditioned reinforcement to better understand how sensitivity to cues are affected in TBI models in rats. In the current study, 16 Long‐Evans rats were subjected to a bilateral frontal controlled cortical impact injury (AP/ML/DV +3.0/, +0.0/, −2.5 @ 3 m/s), while another 16 served as shams. After 10 days recovery, behavior was assessed using a conditioned approach paradigm. This task consists of a lever extending on either the left or right side of the food hopper (variably, every 60s on average), paired with a cue light for five seconds. The left lever and cue signals the presence of a reinforcer (CS+, sucrose pellet). The right lever and cue were never paired with reinforcement (CS‐). Rats was then tested on a conditioned reinforcement (CRf) program on a fixed‐ratio 1 schedule to determine whether they would press a lever merely to obtain the cue light instead of a sucrose pellet. Finally, animals were evaluated on a variable interval program which generated high‐rate pressing, and then were placed in extinction, where only a cue light paired with reinforcement occurred. We found that TBI rats preferentially engaged in goal‐tracking behaviors (responding to the food hopper), ignoring the cues, expended less effort to obtain cues, and were quicker to extinguish behavior. Together, these data suggest a decreased sensitivity to reinforcement‐predictive cues. Further investigation of this phenomenon will be critical to understanding TBI‐induced sensitivity to addictive disorders and have implications for rehabilitative therapies.
Keywords: TBI, Conditioned Reinforcement, Conditioned Approach, Cues
A07 Computational / Modeling
NON‐INVASIVE ALGORITHM FOR SILENCE LOCALIZATION IN STROKE AND TRAUMATIC BRAIN INJURIES
1Carnegie Mellon University, Electrical and Computer Engineering, Pittsburgh, USA
2Carnegie Mellon University, Psychology, Pittsburgh, USA
Keywords: Silence localization, Electroencephalography (EEG), Traumatic Brain Injuries (TBI), Cortical spreading depolarizations (CSDs), Peri‐infarct depolarizations (PIDs), Stroke
SIMULATION OF SPREADING DEPOLARIZATION IN THE HUMAN BRAIN TO EVALUATE THE FEASIBILITY OF DYNAMIC DIFFUSION IMAGING
1Center for Neuroscience and Regenerative Medicine, Bethesda, USA
2National Institutes of Health, Radiology and Imaging Sciences, Bethesda, USA
Detection and localization of cortical spreading depolarizations (CSDs) following traumatic brain injury and stroke may provide valuable information for predicting outcomes and for targeting of therapeutics. Electrocorticography remains the gold standard to detect electrical activity characteric of CSD, but is highly invasive with insufficient spatial resolution to monitor CSD propagation across the three dimensional gyrencephalic cortical surface. Diffusion MRI (dMRI) has been proposed as a means to noninvasively monitor CSD, however while transient changes in apparent diffusion coefficient (ADC) have been observed in animal models of CSD, these findings have not yet been reproduced in humans. We have developed a computational simulation to determine the feasibility of clinical dynamic dMRI when detecting CSD.
We assumed that CSDs radiate from a spherical origin as a wave of altered diffusion properties in cortical gray matter. Our simulation used a manually seeded spherical region in a gray matter mask with 500 μm isotropic spatial resolution and dynamically modeled CSD trajectory using the fast marching method. CSD propagation rate was set to 3mm/minute and voxels within the wave remained active for 60 seconds. The simulation was downsampled to 2x2x4mm spatial resolution and applied to imaging data acquired from healthy volunteers using a Siemens 3T Biograph mMR scanner. A repeating monopolar gradient refocusing pulse sequence was used to collect diffusion data in three orthogonal directions (TR/TE = 3800/82ms, b = 1000 s/mm2) with one non‐diffusion weighted volume (b = 0 s/mm2).
The simulation results suggest that 60 second reductions ranging from 15 to 35% in ADC, values based on animal literature, along with associated increase in trace are distinguishable in cortical gray matter using our clinical dynamic dMRI sequence. Importantly, because CSD in the human brain has yet to be visualized, these results can be used to determine effect sizes and MR acquisition parameters, optimizing clinical dynamic dMRI methods capable of detecting CSD.
Keywords: Spreading Depolarization
OPTIMIZING FREE‐HAND PLACEMENT OF ICP CATHETERS IN BRAIN TRAUMA PATIENTS
1Department of Neurosurgery, Xiangya Hospital, Changsha, China
2Departments of BME and Radiology, Wayne State University, Detroit, US
Keywords: Ventricular cannulation, Surgical simulation, Computed Tomography
ESTIMATION OF AXONAL DAMAGE LOCATION USING WHITE MATTER TRACT EMBEDDED FINITE ELEMENT MODEL
Georgia Institute of Technology & Emory University, The Wallace H. Coulter Department of Biomedical Engineering, Atlanta, USA
Finite element (FE) derived metrics for predicting traumatic axonal injury (TAI) have been limited to predicting absence or presence of TAI rather than estimating the location of injury. We developed an anisotropic FE model with embedded axonal‐tracts to predict sites of acute TAI. Forty‐four piglets experiencing rapid non‐impact head rotation in the axial or sagittal direction were sacrificed 6‐hours post‐TBI, brains perfusion‐fixed, sectioned and stained for beta‐amyloid‐precursor‐protein, and TAI maps were generated. A pig head FE model was enhanced by embedding axonal‐fiber tractography into the brain FE model. Brain and axonal‐fibers were modeled using Holzapfel‐Gasser‐Ogden hyper‐viscoelastic user‐defined material in LS‐DYNA and validated against in‐situ hemisection experiments. We simulated each piglet experiment with measured velocities. For each simulation, six deformation values were extracted from each brain/axonal element's history: maximum principal strain (MPS), strain rate (MPSR), MPSxSR, maximum axonal strain (MAS), strain rate (MASR), and MASxSR. TAI maps were co‐localized to the FE and the minimum distance d between the location of each brain/axonal element and TAI site was calculated. The results of each of the six metrics and d for all elements and all animals were combined. Any element within a distance ds of any TAI was defined as an injured element. All metrics showed higher values at elements closer and lower values at elements farther from TAI sites. For each of the six metrics (x), we examined a matrix of threshold values (thx) and ds to maximize the average of two optimization criteria: correct prediction rate of TAI and TAI detection rate, defined as the percentage of actual TAI sites ≤ds from elements ≥thx. Only the axonal‐deformation‐related metrics showed promise, with a 91‐93% TAI detection rate and 72‐76% correct prediction rate for TAI. The optimal ds (and thx) for MAS, MASR, and MASxSR were 2.5mm(0.12), 2mm(50/s), and 2mm(3/s). Overall, axonal deformation‐related metrics reliably predict the sites of acute TAI acutely ≤2.5mm. Funded by Biocore Co., Ltd., NIH‐R01NS097549, and 2R56NS055951‐10A1.
Keywords: Anisotropy Modeling, Histopathology Analysis, FEM‐Histopathology Co‐localization, Tractography, Tissue Injury Metrics, White Matter Tracts Modeling
A COMPUTATIONAL APPROACH TO THE DEVELOPMENT OF A STANDARDIZED UNILATERAL SPINAL CORD CONTUSION INJURY MODEL
1Simon Fraser University, Mechatronic systems engineering, Surrey, Canada
2International Collaboration on Repair Discoveries, Vancouver, Canada
3Brain and Spinal cord center, San Francisco, USA
Animal models of spinal cord injury (SCI) have been developed with the aim of mimicking the characteristics of human spinal cord injury to increase knowledge of injury mechanisms, evolution of injury and provide a clinically relevant platform for developing and evaluating therapies. Cervical contusion is the most prevalent pattern of injury in humans, however, cervical spinal cord animal models are challenging since the severe lesion caused by a bilateral contusion can kill the animal or result in severe injuries that are too complex and expensive to care for. Therefore, cervical unilateral SCIs have been developed; however, they are limited by significant variability and bulk cord movement during the impact. For the unilateral contusion injury models to provide a platform for testing pre‐clinical trials, these models are required to be characterized and standardized which requires generating consistent, equivalent, repeatable and reproducible injury on the animals. A unilateral contusion finite element model was generated based on data extracted from in‐vivo SCI experiments on different species and our recent constitutive material and finite element models. The spinal cord constituent materials (gray and white matter and pia and dura mater) were simulated using quasi‐linear viscoelastic materials and the white matter included anisotropy. A quasi‐static preload pre‐compressed the dura and was followed by a rapid contusion impact. Parametric finite element analysis quantified the effects of impactor mediolateral alignment, impactor shape, angle and rate of approach, spinal cord trapping depth and speed, positioning and preload on the resulting contusion injury in the context of output mechanical measures. Preliminary results confirmed that the impactor mediolateral alignment substantially affect the output impactor force. Quantifying the relationship between impact mechanics and injury outcomes is important for better understanding potential sources of variation in contusion model outcomes, and for improving the reproducibility of these animal models of contusion SCI.
Keywords: contusion, parametric finite element analysis, cervical spinal cord injury
EFFECTS OF CONCOMITANT MEDICATIONS ON PHARMACOKINETICS OF RILUZOLE THERAPY IN PATIENTS WITH ACUTE SPINAL CORD INJURY
1University of Houston, Department of Pharmacological and Pharmaceutical Sciences, Houston, USA
2Houston Methodist Neurological Institute, Department of Neurosurgery, Houston, USA
3PRA Health Sciences, Lenexa, USA
Evaluation of a potential risk of metabolic drug–drug interactions is of significance in clinical settings. In this study, we investigated the effects of two most common concomitant medications in SCI patients, oxycodone (in 40% of SCI patients) and acetaminophen (41%), on the pharmacokinetics of riluzole in clinical trials. A population pharmacokinetic modeling was used, taking into account the clinical progressive course of SCI. The model was developed using 219 observations from 46 patients participated in Phase I and ongoing Phase II (RISCIS) trials investigating safety, pharmacokinetics, and preliminary efficacy of riluzole in patients with acute SCI. Riluzole was given orally at 50 mg (Phase I) or 100 mg loading dose (Phase II) within 12 hr of injury, BID on the first day, followed by 50 mg BID for the remaining 13 days. The plasma samples were collected before and at 3 hours post dose and quantified using a validated LC‐MS/MS assay to derive Ctrough and Cpeak, respectively, for Days 3, 7, 10 and 14 post injury. One compartment with first order elimination population model fitted well using Phoenix 8.0 software with additive error model to account for residual variability. FOCE ELS approach was employed to estimate absorption rate constant (ka), clearance (CL/F), and volume of distribution (V/F), which were 5.9 h−1, 73 L·h−1, and 905 L, respectively. CL/F and V/F increased by factors of N0.27 and N0.37, respectively, where N is the days‐post‐injury. The CL/F of riluzole increased by e0.54 with concomitant oxycodone as a significant covariate, but not affected by acetaminophen. This PK model offers a potential guidance for rational dosing adjustments of riluzole post spinal cord injury and with concomitant oxycodone in spinal cord injured patients.
Keywords: pharmacokinetics, concomitant medication, drug interaction, clinical trial
USE OF SUPERVISED MACHINE LEARNING TO PREDICT INCOMPLETE RECOVERY IN PATIENTS WITH MILD TRAUMATIC BRAIN INJURY (MTBI)
University of Michigan, Ann Arbor, USA
Mild traumatic brain injury (mTBI) is a major cause of morbidity in the United States. The pathophysiology of mTBI is multifactorial and heterogeneous and while the majority of patients recover completely, a portion still experience persistent post‐concussive symptoms beyond 1‐ month post‐injury. Currently, the development of accurate prediction models for patients with mTBI remains an unmet clinical challenge and novel solutions are urgently needed as existing models for mTBI have performed unsatisfactorily thus far. HeadSMART (Head Injury Serum Markers for Assessing Response to Trauma) is a prospective cohort study that enrolled patients with blunt head trauma who presented to two urban academic Emergency Departments within 24 hours of injury and who received a head CT as part of their clinical care. A total of 549 participants were enrolled, and of those, 421 participants had complete follow‐up data, including GOSE score at 1‐month post‐injury. We compared the predictive accuracies of models for predicting incomplete recovery (GOSE <8) at 1‐ month post‐injury. These models were derived using three machine learning algorithms: logistic regression (LR), random forest (RF) and support vector machine (SVM). Automated feature selection methods were used to identify the most relevant, non‐correlated features. These features were: age (p < .001), mechanism of injury (p < .001), head abbreviated injury scale (AIS) (p < .001), Glasgow Coma Scale (GCS) <15 on presentation (p < .001) and altered mental status (AMS) (p < .001). The model derived using SVM demonstrated the highest discriminative value with an area under the receiver operating characteristic curve (AUC) of 0.79. The models derived using logistic regression and random forest had AUCs of .66 and .61, respectively. Our preliminary analyses demonstrate the potential utility of machine learning methods for outcome prediction in mTBI. We hypothesize that in addition to the clinical and demographic variables selected for inclusion in the current analysis, model integration and the addition of molecular data in the form of blood‐based biomarkers may further improve the predictive accuracy of our models.
Keywords: computational, machine learning, biomarker, prognostication
A08 Epilepsy / Seizure
DEVELOPMENT OF AN ANALYTICAL PIPELINE FOR POST‐TRAUMATIC EPILEPSY IN A PRECLINICAL MODEL OF ANTI‐EPILEPTOGENESIS FOLLOWING TBI
1David Geffen School of Medicine at UCLA, Neurology, Los Angeles, USA
2David Geffen School of Medicine at UCLA, Neurosurgery, Los Angeles, USA
3University of California Los Angeles, Los Angeles, USA
About 15‐20% of TBI cases develop PTE, a potentially life‐threatening condition. To date, no established biomarkers have emerged, though several strong candidates have been described. Further, there is no clinically‐validated anti‐epileptogenic treatment to prevent PTE. As part of the EpiBioS4Rx consortium, we present an analytical pipeline for a preclinical, anti‐epileptogenic model of PTE. An important component of this pipeline is recording EEG activity after TBI and assessing the potential anti‐epileptogenic effects of drugs on normal and abnormal EEG events in injured and sham‐control rats. This study serves as a progress report on an ongoing preclinical pharmacological interventional study in a rodent model. TBI was induced in adult, male Sprague Dawley rats using the lateral fluid percussion injury model, and depth and screw electrodes were placed using a stereotaxic apparatus. A subdermal osmotic pump with drug/vehicle was placed at the time of surgery and removed after 7 days. EEG data were collected immediately following TBI for 24 hours/day for 14 days. EEG sample rate was 2 kHz with a bandpass filter of 0.1‐1000 Hz. The investigator responsible for implanting the pump and collecting EEG data was blinded to its contents. In injured and sham‐controls, preliminary analysis found spike and wave discharges, and high‐frequency oscillations, which could be a biomarker of epileptogenesis. Electrographic seizures similar to those found in status epilepticus models of epilepsy were detected in most injured rats and a few sham‐controls. Due to the design, the authors remain blinded to the drug‐treatment status of the rats. These data indicate several electrographic epileptiform events that occur after TBI and serve as the focus of our preclinical, anti‐epileptogenic intervention studies of PTE. Funding: EpiBiosS4Rx grant–5U54NS100064
Keywords: Post‐Traumatic Epilepsy, EEG, Epileptogenesis, anti‐epileptogenic intervention
THE CRANIECTOMY PROCEDURE AFFECTS THE OCCURRENCE OF ACUTE EEG SEIZURES IN A TRAUMATIC BRAIN INJURY ANIMAL MODEL
1David Geffen School of Medicine at UCLA, Neurology, Los Angeles, USA
2David Geffen School of Medicine at UCLA, Neurosurgery, Los Angeles, USA
The lateral fluid‐percussion injury (LFPI) animal model is commonly used to study Traumatic Brain Injury (TBI). Despite the widespread use of this model in numerous published studies of TBI there is considerable variability in the surgical procedures that could affect the injury and possibly neurological sequela such as post‐traumatic seizures. Thus, the focus of this study was to compare two different craniectomy methods in the LFPI rat model on the basis of acute EEG seizure activity after injury. A craniectomy was performed with either a trephine (M‐TBI) or electric drill (D‐TBI) that was centered over the left hemisphere of adult, male Sprague Dawley rats (n = 19). Then, TBI was induced in both groups using a fluid‐percussion device. Sham groups (M‐S/D‐S) underwent the same surgical procedures as the TBI rats, but TBI was not induced. During the same surgery session, rats were implanted with screw and microwire electrodes positioned in neocortex and hippocampus and the EEG activity was monitored 24/7 during the first week after TBI. The initial review found that acute EEG seizures occurred in 100% of TBI rats 20.7 ± 4 h after TBI. The animals from the D‐TBI group had a significant greater total number of seizures (79 vs 20 seizures; p < 0.05) that were 20% shorter in duration (64 vs 80 sec; p < 0.05) than the number of seizure and their duration in the M‐TBI group. Ongoing analysis will assess the spatial and temporal profile of acute seizures in M‐TBI and D‐TBI rats. The results suggest that trephine versus electric drilling craniectomy could produce cortical injury in addition to the LFPI that increases the likelihood for early post‐traumatic seizures. Differences in the surgical approach could be one reason for the variability in the injury that makes it difficult to replicate results between preclinical TBI studies.
Keywords: EEG, TBI, Seizure, Animal Model
LONGITUDINAL IMAGING OF MICROSTRUCTURAL CHANGES IN THE BRAIN FOLLOWING FLUID PERCUSSION INJURY: AN IMAGING BIOMARKER STUDY FOR PTE
1David Geffen School of Medicine at UCLA, Neurosurgery, Los Angeles, USA
2David Geffen School of Medicine at UCLA, Neurology, Los Angeles, USA
As part of an on‐going pre‐clinical, multi‐center study (EpiBiosS4Rx) powered to detect imaging biomarkers of post‐traumatic epilepsy (PTE), we report on a rodent pipeline developed for unbiased, quantitative, high throughput analysis of MRI data obtain by diffusion‐weighted imaging (DWI) and susceptibility‐weighted imaging. Microstructural abnormalities are quantified by fitting the data to a tensor model to calculate scalar indices of the tensor, region‐specific tract‐based analysis of structural connectivity using constrained spherical deconvolution and probabilistic tractography. Fixel‐based analysis was conducted to obtain counts of fiber density and fiber cross‐section in order to determine injury‐related differences also related to brain structural connectivity. Tensor‐based morphometry (TBM) analysis was applied to structural data to quantify the extent of tissue atrophy within the injured brain, as a gross correlate of injury severity. Quantitative susceptibility mapping (QSM) analysis was used to determine the extent of heme deposition and bleeding following TBI. TBI was induced in adult, male, Sprague Dawley rats using the lateral fluid percussion injury model and 250 mm3 isotropic, DWI data (b = 0,2800 s/mm2, 42 gradient vectors) were acquired longitudinally on a 7T Bruker spectrometer. Structural, T2‐weighted and multi‐gradient echo T2*, 160 μm3 isotropic (TR 77ms, 13 echoes) data were acquired at: 2days, 9days, 1month and 5months post injury for both injured (n = 21) and sham rats (n = 12). Phenotyping for PTE using EEG analysis will occur at 7months. Preliminary data analysis indicates that in agreement with prior published data in this model, fixel‐based analysis for fiber density provide useful measures that discriminates between uninjured and injured brain regions. In a subset of animals phenotyped for seizure activity, our on‐going analysis of microstructure and tractography, TBM and QSM data will be used to determine the efficacy of imaging biomarkers to discriminate between rats that develop PTE vs. those that do not following severe TBI.
Keywords: Post‐traumatic epilepsy, Diffusion‐weighted imaging, Tensor‐based morphometry, Quantitative susceptibility mapping
MISLOCALIZATION OF AQUAPORIN‐4 IN A CONTROLLED CORTICAL IMPACT INJURY MODEL OF POSTTRAUMATIC EPILEPSY
University of California, Riverside, Division of Biomedical Sciences, Riverside, USA
Posttraumatic epilepsy (PTE) is a long‐term negative consequence of traumatic brain injury (TBI) in which recurrent spontaneous seizures occur after the initial head injury. PTE develops over an undefined period where circuitry reorganization in the brain causes permanent hyperexcitability. Unfortunately, current existing antiepileptogenic drugs have all failed at treating PTE, and thus, there is a critical need to identify biomarkers of PTE to develop new therapeutic strategies. The pathophysiology by which trauma leads to spontaneous seizures is unknown and clinically relevant models of PTE are key to understanding the molecular and cellular mechanisms underlying the development of PTE. Current animal studies of PTE are limited and comprehensive in vivo electrophysiological approaches remain absent. In the present study, I aimed to identify electrographic biomarkers of PTE with correlation to hippocampal histopathology at various time points after injury. Here, adult male CD1 wildtype (WT) and aquaporin‐4 knockout (AQP4 KO) mice were subjected to a moderate‐severe TBI in the right frontal cortex using the well‐established controlled cortical impact (CCI) injury model. Additionally, mice underwent in vivo video‐electroencephalographic (vEEG) recordings and immunohistochemistry and Western blot analysis for the key epileptogenic astrocytic channel AQP4. The main findings from these studies are: 1) successful implementation of CCI‐based PTE in mice with chronic vEEG generated, for the first time, 17% and 27% of WT and AQP4 KO mice with PTE, respectively (the highest yield of PTE reported); 2) AQP4 KO mice had a greater incidence of spontaneous seizures and PTE compared with WT mice; 3) EEG power patterns are different between mice with and without PTE; and 5) AQP4 is significantly upregulated in the frontal cortex and hippocampus of mice with PTE suggesting possible mislocalization of the water channel. Collectively, these findings identified specific PTE EEG phenotypes that may be modulated by AQP4 and carry significant implications for epileptogenesis after TBI which may serve as the first steps to developing surrogate biomarkers of PTE.
Keywords: posttraumatic epilepsy, biomarker, EEG, aquaporin‐4
CHARACTERIZING GENETIC RISK FACTORS OF SEIZURES FOLLOWING TRAUMATIC BRAIN INJURY
1University of Pittsburgh, Physical Medicine & Rehabilitation, Pittsburgh, USA
2Icahn School of Medicine at Mount Sinai, Rehabilitation Medicine, New York, USA
3University of Pittsburgh, School of Nursing, Pittsburgh, USA
4University of Pittsburgh, Clinical and Translational Science Institute, Pittsburgh, USA
5University of Pittsburgh, Safar Center, Pittsburgh, USA
Post‐traumatic seizures (PTS) occur in an estimated 20% of individuals with moderate‐to‐severe traumatic brain injury (TBI). Individuals with PTS are 37 times more likely to die as a result of seizures compared to the general population. Risk factors of PTS include craniotomy, craniectomy, and subdural hematoma (SDH). Our work has previously identified relationships between PTS and 6 single nucleotide polymorphisms (SNPs) related to genetic variation of glutamatergic, GABAergic transport, and interleukin 1ß. In a cohort of n = 209 adults with moderate‐to‐severe TBI, we created a gene risk score (GRS) using 6 SNPs (GRS6, n = 203) and in a subset of 4 SNPs (GRS4, n = 209), as aggregate measures of genetic risk. The sum of risk alleles carried by each individuals established an individual's unweighted GRS (uGRS). We assigned weights for each SNP using ß‐values from logistic regression models for each SNP to PTS, calculating weighted GRS (wGRS) by summing weights for risk alleles. We tested relationships between uGRS and wGRS with one‐year PTS events via logistic regression, controlling for age, sex, and clinical covariates. Both uGRS (uGRS4 OR = 1.43, p = 0.071; uGRS6 OR = 8.39, p = 0.008) and wGRS (wGRS4 OR = 8.39, p = 0.001; wGRS6 OR = 6.09, p < 0.001) predicted PTS risk. We compared receiving operating characteristic (ROC) curves of base regression models, including covariates alone, to models including GRS. wGRS improved area under the base model ROC curve, with final variance capture >0.83, indicating strong PTS status discrimination. Future research evaluating and validating genetic risk factors for PTS can support a precision medicine approach to PTS risk, prognosis, and management. Support: CURE Foundation, NIH R01 HD048162.
Keywords: genetic risk, post‐traumatic seizures, traumatic brain injury
M‐CURRENT AUGMENTATION REDUCES TBI‐INDUCED NEURONAL HYPEREXCITABILITY AND POST‐TRAUMATIC EPILEPSY
1UTHSA, Cell and Integrative Physiology, San Antonio, USA
2UTHSA, Cell & Structural Biology, San Antonio, USA
3UTHSA, Neurology, San Antonio, USA
Nearly 3 million people in the U.S.A. suffer traumatic brain injury (TBI) yearly. However, there are no treatment options available for TBI. KCNQ2‐5 voltage‐gated K+ channels underlie the “M‐current,” which plays a dominant role in the regulation of neuronal excitability. Our strategy towards prevention of TBI‐effects is to block hyperexcitability of neurons with pharmacological augmentation of M/KCNQ currents. Seizures are very common after a TBI, making the development of epilepsy disease more likely. We have previously shown, in a blunt injury mouse model, that TBI‐induced hyperexcitability, metabolic stress, cell death, the immunologic/inflammatory response, and blood‐brain barrier leakage can be impaired by one acute dose of pharmacological M‐current augmentation. Our pilot experiments using two‐photon in vivo imaging of mice expressing GCaMP6, show TBI to induce an increase in firing frequency, and a decrease in inter‐event interval, but no significant change in firing peak amplitude. There was also no observable change in network organization, besides an increase in the number of active neurons. Imaging neuronal [Ca2+]i in cortical slices as a reporter of activity revealed neurons to respond more intensely to stimulation by Kainic acid after a TBI. We are currently performing two‐photon and slice imaging experiments testing the effects of M‐current augmentation in the TBI‐induced increases in neuronal [Ca2+]i. Finally, using a blast TBI model, we observed that the incidence of post‐traumatic epilepsy (PTE) in aged mice (1 year) was reduced by M‐current openers. We previously reported that the same blast model induces an acute increase in total Tau levels and Tau phosphorylation. Taken together, our results support pharmacological M‐current increase as an effective post‐TBI treatment. Our data show beneficial effects that go beyond reduction of neuronal hyperexcitability. This work is supported by DoD CDMRP grants W81XWH‐15‐1‐0284 and W81XWH‐15‐1‐0283.
Keywords: M current, Hyperexcitability, Blast, Concussion, Two‐photon, EEG
EARLY POST‐TRAUMATIC SEIZURES DO NOT CORRELATE WITH MOSSY FIBER OUTGROWTH IN SUB‐ACUTE PHASE OF TBI IN RATS
Walter Reed, BTNN, Silver Spring, USA
It is unknown whether early post‐traumatic seizures are associated with the development of chronic post‐traumatic epilepsy. Mossy fiber sprouting in the hippocampus has been implicated in epileptogenesis and may play a crucial role in the development of post‐traumatic epilepsy. In this study we examined whether mossy fiber sprouting was associated with early post‐traumatic seizures 2 weeks after a penetrating traumatic brain injury (pTBI) as a potential mechanism of post‐traumatic epileptogenesis. Rats received skull EEG electrode implantation bilaterally over the frontal and parietal cortices. PTBI was performed through the right frontal cortex 3 days after EEG surgery. Spontaneous seizures were detected by continuous video‐EEG recording for 72 hours following injury. Mossy fiber outgrowth was examined in the pyramidal and granular cell layers of the hippocampus bilaterally and scored on a 3 point scale. Seizure frequency was correlated with mossy fiber outgrowth at 2 weeks following brain injury. The majority of PTBI rats (74%) experienced non‐convulsive seizures detected by EEG during the 72‐hour post‐injury monitoring period with an average frequency of 18.05 ± 5.3 seizures per animal (range: 0‐69 seizures). Scores for mossy fiber outgrowth were low amongst all animals with an average score of 1.08 ± 0.15 in the pyramidal cell layer and 0.85 ± 0.10 in the granular cell layer. However, no significant correlations were detected between acute seizure frequency and mossy fiber outgrowth at 2 weeks post‐injury. Low mossy fiber sprouting scores at 2 weeks post injury may indicate a slow process of post‐traumatic epileptogenesis. Additional longitudinal studies are needed to correlate the time‐course of mossy fiber sprouting and the development of delayed post‐traumatic epilepsy during a longer latent period.
Keywords: Ballistic injury, seizure, mossy fiber, preclinical
ANTI‐SEIZURE DRUG COMBINATION THERAPY IN A RAT MODEL OF POSTTRAUMATIC SEIZURES INDUCED BY PENETRATING BALLISTIC‐LIKE BRAIN INJURY
Walter Reed Army Institute of Research, Brain Trauma Neuroprotection, Silver Spring, USA
Keywords: Anti‐Seizure Drugs, Phenytoin, Ethosuximide, Levetiracetam, Gabapentin, Combination Therapy, Isobolographic analysis
A09 Hemorrhage
NEUROSURGICAL OUTCOMES OF ISOLATED HEMORRHAGIC MILD TRAUMATIC BRAIN INJURY
1Advocate Health Care, Neurosurgery, Downers Grove, USA
2Advocate Health Care, Trauma, Downers Grove, USA
3University of Illinois Chicago, Surgery, Chicago, USA
Keywords: intracranial hemorrhage, neurosurgical intervention
TRAUMATIC SUBARACHNOID HEMORRHAGE AS A RISK FACTOR FOR MORTALITY OF PATIENTS WITH MODERATE AND SEVERE TRAUMATIC BRAIN INJURY
1Hospital Central de Maracay, Neurocirugia, Maracay, Venezuela
2Universidad de Carabobo, Anatomia, Maracay, Venezuela
3Hospital Clinico Magallanes, Neurocirugia, Punta Arenas, Chile
Keywords: Traumatic subarachnoid hemorrhage, Moderate TBI, Severe TBI, Fisher Scale, Modified Fisher Scale
SOCIAL STRESS POTENTIATES NEGATIVE OUTCOMES FOR MALE PRAIRIE VOLES (MICROTUS OCHROGASTER) IN POLYTRAUMATIC INJURY
1Naval Medical Research Unit, Combat Casualty Care, Fort Sam Houston, USA
2Northern Illinois University, Department of Psychology, DeKalb, USA
Psychological factors are known to influence long‐term health; however, there is a dearth of evidence evaluating its impact upon biological and behavioral outcomes following injury. This experiment utilized prairie voles because they regulate cardiac function similar to humans and have been successfully used to model autonomic and cardiac dysfunction, compromised complement and innate immunity, and endothelial dysfunction. All subjects (N = 25) were housed in male/female pairs for 5 days, then half of the pairs were isolated (for 7 days) resulting in 4 injury study groups: (1) Paired‐Female; (2) Paired‐Male; (3) Isolated‐Female; (4) Isolated‐Male and (5) Anesthesia‐Shams. On injury day, electrocardiogram was monitored and all animals received a traumatic brain injury (TBI) impact then ∼30% hemorrhage. Animals were held for 1 hour, then resuscitated with 2x Lactated Ringers bolus (with 1 hour wait), allowed to regain consciousness (20 minute stabilization period); procedure ended with an open field behavior test and tissue collection. All isolated subjects displayed significantly higher mortality (p = 0.050); Isolated‐Males were more likely to die than Paired‐Males (p = 0.080). Electrocardiogram data indicates significantly elevated heart rate for injury animals over Anesthesia‐Shams and impaired cardiac regulation (i.e. decreased heart rate) during resuscitation for Isolated‐Males (p = 0.003). Isolated‐Males were unable to complete the open field, but Isolated‐Females tended to display elevated anxiety‐like behavior (p = 0.129). Isolated‐Males displayed significantly higher glucose (p = 0.015), lower anion gap (p = 0.011), and tended to have a higher iCa (p = 0.125). Size issues limited other group blood comparisons. Results imply the polytrauma prairie vole injury model can be used to further investigate the psychological factors that impact traumatic injury recovery. This model provides insight into the protective influence of social bonds on recovery from a physical injury, potentially informing future interventions and treatment strategies.
Keywords: social stress, traumatic brain injury, resuscitation, polytrauma
NEUROPROTECTIVE STRATEGIES IN A NOVEL PRECLINICAL MODEL OF SUBARACHNOID HEMORRHAGE
1Seattle Children's Hospital/University of Washington, Pediatrics, Division of Critical Care, Seattle, USA
2Seattle Children's Hospital/University of Washington, Pediatrics, Division of Neonatology, Seattle, USA
3Seattle Children's Research Institute, Center for Integrative Brain Research, Seattle, USA
4University of Washington, Pediatrics, Division of Genetics, Seattle, USA
Cerebellar abnormalities, particularly those related to cerebellar hemorrhage (CBH), have become increasingly associated with preterm birth and adverse neurodevelopmental outcomes. The mechanism by which CBH affects the developing cerebellum is largely unknown. Our objectives were to develop a novel murine model of preterm posterior fossa subarachnoid hemorrhage and determine the effects on cerebellar development. In this study, whole blood (20 μl) or artificial cerebrospinal fluid (aCSF) (20 μl) was injected into the posterior fossa of post‐nasal day (P)6 C57BL/6J and CD1 mice. Animals in both blood and aCSF groups were administered either ketoprofen (n = 4/group) or buprenorphine (n = 4/group). At P8, immunohistochemistry targeting BrdU (cell proliferation and migration), Caspase‐3 (cell death), GFAP (Bergman glia), and Calbindin (Purkinje cells) was performed. In C57BL/6J mice, blood injection resulted in significant infiltration of inflammatory cells at P8 compared to aCSF. Stunted Purkinje arborization, abnormal Purkinje cell density (13.3 ± 0.5 cells/200 μm vs. 8.4 ± 0.5 cells/200 μm, p < 0.05), thinning of the molecular layer (30.0 ± 0.7 μm vs. 33.5 ± 0.9 μm, p < 0.05), and decreased complexity of Bergmann glial fiber processes (29.1 ± 0.4 crossing/100 μm vs. 32.7 ± 1.0 crossings/100 μm, p < 0.05) was also observed. Ketoprofen administration resulted in partial injury attenuation. Preliminary data from CD1 mice further demonstrates decreased external granule layer (EGL) thickness and abnormal distribution/architecture of Purkinje cells. These studies are ongoing. Our findings demonstrate that subarachnoid hemorrhage results in significant injury and derangement of cerebellar developmental programs in neonatal mice with alterations to cerebellar granule, Bergmann glial, and Purkinje cell types. Partial attenuation of injury with ketoprofen suggests neuroinflammation as a key factor and potential therapeutic intervention. Further studies to more fully elucidate the mechanism by which blood disrupts the developing cerebellum and contributes to cerebellar hypoplasia are ongoing.
Keywords: Cerebellum, Development, Neuroprotection, Neuroinflammation
BUMETANIDE PROMOTES FUNCTIONAL RECOVERY OF HINDLIMB FUNCTION AND REDUCES HEMORRHAGE AFTER SPINAL CORD INJURY
Texas A&M University, Psychology, College Station, USA
Spinal cord injury (SCI) is often accompanied by additional injuries (polytrauma) that provide a source of pain input. It has been shown that engaging pain (nociceptive) fibers caudal to a lower thoracic contusion injury impairs long‐term recovery. This effect has been related to increased tissue loss at the injury site, attributed to blood‐spinal cord barrier breakdown and infiltration of blood (hemorrhage). Our previous studies have shown that moderate pain input can trigger hemorrhage after SCI and undermine long‐term recovery. In addition, noxious input can sensitize nociceptive circuits within the spinal cord, inducing a lasting increase in spinal cord neural excitability (central sensitization) that is thought to contribute to chronic pain. The development of spinally‐mediated central sensitization is regulated by descending fibers and GABAergic interneurons. Previous work suggests that SCI transforms how GABA affects nociceptive transmission within the spinal cord by reverting to an earlier developmental state wherein GABA has an excitatory effect. The effect of SCI on GABA function was linked to a reduction of the Cl− transporter, KCC2, leading to a decrease in intracellular Cl− that attenuates GABA‐mediated inhibition. Our studies suggest that GABAergic neurons drive the development of nociceptive sensitization after SCI. Given this data, we examined the effects pharmacological treatment (bumetanide) has on both promoting functional recovery and reducing hemorrhage. Rats were given a moderate contusion at T12 and then treated 24‐hours later. Animals received an epidural injection of either 1mM bumetanide or vehicle saline solution, then received either six‐minutes of uncontrollable intermittent electrical stimulation to the tail or none at all. After treatment, blood pressure and BBB locomotor scores were evaluated at 0, 1, 2, and 3 hours. Animals were then sacrificed and spinal tissue centered on the lesion site was collected to analyze the extent of hemorrhage. Findings suggest that Bumetanide promotes recovery of hindlimb function and reduces hemorrhage. Supported by a grant from the NIH (NS104422) to JWG.
Keywords: Spinal Cord Injury, Functional Recovery, GABA, Pain
EFFECTS OF AIR‐EVACUATION‐RELEVANT HYPOBARIA ON FERRETS FOLLOWING POLYTRAUMA
Univ. of Maryland School of Medicine, Anesthesiology, Baltimore, USA
Rats exposed to aeromedical evacuation (AE)‐relevant hypobaria within seven days after traumatic brain injury (TBI) alone or with hemorrhagic shock (HS) exhibit greater neurologic injury and mortality than those maintained normobaric. The applicability to humans may be limited by major differences in brain neuroanatomy. Like humans, ferrets have a gyrencephalic brain. We therefore developed a ferret polytrauma (PT) model consisting of controlled cortical impact (CCI) followed by mild HS. The objective was to determine if the deleterious effects of hypobaria observed in rats after TBI are also observed in a species with a gyrencephalic brain. Anesthetized adult male ferrets were subjected to CCI and HS by withdrawing blood to maintain MAP 35‐45 mm‐Hg for 30‐min. Resuscitation with Hextend was followed one hr later by blood re‐infusion. At 24 hr, ferrets were placed in a “flight” chamber for 6‐hr and exposed to normobaria or to hypobaria ( = 8000 ft) under 21% or 28% O2, respectively. MRI and MRS measurements were performed prior to injury and 2 days later. Behavioral tests included a novel object location test for spatial memory. Brains were fixed on day‐7, immunostained for IBA‐1(microglia) and used for quantification of cortical lesion volume and activated penumbral microglia. In contrast to our rat PT model that results in 30–60% mortality, no ferret deaths occurred. Ferrets exposed to hypobaria after PT performed worse on the novel object location test compared to those maintained under normobaria. The percent lesion volume was similar to that of rats, whereas microglial activation was more extensive. MRS results obtained at 48‐hr indicate significant reduction in cortical levels of creatine, N‐acetyl aspartate, GABA and glutamate after polytrauma. To our knowledge this is the first ferret polytrauma model combining CCI plus HS. Despite neuropathology that was comparable to that of rats, there was no ferret mortality. Preliminary results indicate that exposure to hypobaria adversely affects behavior and may increase neuroinflammation. Supported by US Air Force FA8650‐15‐2‐6D21.
Keywords: ferret, hypobaria, magnetic resonance spectroscopy
MULTIFACETED BENEFIT OF WHOLE BLOOD VERSUS CRYSTALLOID RESUSCITATION AFTER TRAUMATIC BRAIN INJURY AND HEMORRHAGIC SHOCK IN MICE
1University of Pittsburgh, Safar Center for Resuscitation Research, Pittsburgh, USA
2Walter Reed Army Institute of Research, Center for Military Psychiatry and Neuroscience, Silver Spring, USA
3Uniformed Services University of the Health Sciences, Department of Surgery, Bethesda, USA
We reported that whole blood (WB) resuscitation, versus lactated Ringer's (LR), produces sustained improvement in mean arterial pressure (MAP) in a murine model of TBI with hemorrhagic shock (HS). However, the effect of WB resuscitation on brain‐tissue oxygenation (PbtO2) and optimal MAP target remain undefined.
Anesthetized mice (n = 72) underwent controlled cortical impact followed by HS (MAP = 25‐27mmHg). Mice were randomized to four groups for a 90 min “prehospital” resuscitation: LR with MAP targetof 60 mmHg (LR60), WB60, LR70, and WB70. Mice were bolused 20mL/kg of autologous WB or LR, followed by LR boluses (10ml/kg) every 5 min for MAP below target. Shed blood was reinfused in a “hospital” phase. Forty mice had PbtO2 measured. Mice were sacrificed (3 or 24h) to determine hemispheric percent brain water (%BW, wet‐dry weight). Comparisons were made by repeated measures ANOVA.
LR required in WB60 (7.2 ± 21.4mL) and WB70 (28.3 ± 40.1mL), were markedly lower than in either LR60 (132.8 ± 24.5 mL) or LR70 (152.2 ± 28.3mL) [p < 0.001; all comparisons]. LR requirements between WB groups were similar. MAP in WB70 (72.4 ± 5.1mmHg) was higher than in LR70 (p < .001, [60.2 ± 8.3mmHg]), WB60 (p = .03, [68.5 ± 7.0mmHg]), and LR60 (p < .001, [53.6 ± 7.4mmHg]). MAP in WB60 was higher than in LR70 or LR60 (p < .001). WB60 and WB70 had higher PbtO2 (43.8 ± 13.1 and 40.7 ± 10.4mmHg, respectively) than LR70 ([24.1 ± 9.8mmHg], p = 0.003 and p = 0.01, respectively). PbtO2 in WB60 was higher than PbtO2 in LR60 ([25.9 ± 13.4mmHg], p = .04). PbtO2 between WB groups was similar. %BW was similar between groups.
WB, vs LR, resuscitation after TBI+HS rapidly normalizes MAP and cerebral dysoxia, while reducing fluid requirements and allowing for lower MAP target. Future studies on functional outcomes are warranted.
SUPPORT: USDoD, W81XWH‐17‐C‐0064
Keywords: Hemorrhagic Shock, CCI, Whole Blood, Resuscitation
LATENT CLASS TRAJECTORY ANALYSIS OF CSF BRAIN‐DERIVED NEUROTROPHIC FACTOR METHYLATION FOLLOWING SUBARACHNOID HEMORRHAGE IN ADULTS
1University of Pittsburgh School of Medicine, Physical Medicine & Rehabilitation, Pittsburgh, USA
2Duke University, Population Health Sciences, Durham, USA
DNA methylation is a tissue‐specific epigenetic modification by which the social and biological environment of an individual can impact when and to what extent genes are expressed within each cell type. Methylation is a means of gene regulation with higher levels rendering the gene less transcriptionally active. Experimental models suggest that acquired brain injury results in alterations to methylation. The brain‐derived neurotrophic factor (BDNF) gene plays a role in neuroplasticity and repair and is sensitive to epigenetic modification.
Our objectives were to: (1) explore concordance between cerebrospinal fluid (CSF) and blood BDNF methylation following subarachnoid hemorrhage (SAH) in adults across the BDNF gene; and (2) characterize CSF BDNF methylation trajectories during the acute recovery period in the CpG islands with high concordance.
In adults with SAH, blood samples from the first day of hospitalization and serial CSF samples from the first 14 days were available. M‐values obtained after a stringent data‐cleaning pipeline were analyzed.
Spearman correlations in 37 patients with both CSF and blood BDNF methylation showed moderate to very strong positive correlations (r = .39‐.81; p = .02‐<.0001) in 6 of 45 BDNF CpG islands. For the 6 CpG islands with the highest correlations between CSF and blood BDNF methylation, latent class trajectory analysis in 273 patients with serial CSF samples revealed 2‐3 trajectory classes of decreasing methylation post‐SAH. Results suggest that BDNF methylation in CSF and blood is correlated in a small proportion of CpG islands. In these concordant islands, CSF BDNF methylation shows multiple trajectory classes and suggests that the BDNF gene may be upregulated during acute recovery following SAH in adults.
Funding: R01NR013610; KL2 TR001856 03; T32 HD040686‐16
Keywords: subarachnoid hemorrhage, epigenetic, BDNF, methylation, acquired brain injury
DNA METHYLATION TRAJECTORIES IN THE AMYLOID PRECURSOR PROTEIN GENE AND PATIENT OUTCOMES AFTER SUBARACHNOID HEMORRHAGE
University of Pittsburgh, Pittsburgh, USA
The purpose of this study was to examine the relationship between DNA methylation in the amyloid precursor protein gene (APP), a central player in neural plasticity and iron export, and outcomes after aneurysmal subarachnoid hemorrhage (SAH). As part of a longitudinal observational study, participants with aneurysmal SAH were phenotyped for in‐hospital acute outcomes (cerebral vasospasm [CV] and delayed cerebral ischemia [DCI]) and 3 and 12 month long‐term outcomes (death and functional status using the Glasgow Outcome Scale [GOS; unfavorable = 1‐3]). Methylation data were collected from DNA extracted from cerebrospinal fluid over 14 days post‐SAH at 21 methylation sites within APP. Using group‐based trajectory analysis, participants were assigned to trajectory classes based on site‐specific DNA methylation data, with and without correcting for cell type heterogeneity (CTH). The associations between inferred DNA methylation trajectory groups and patient outcomes were tested using logistic regression while controlling for age, sex, race, and Fisher grade. In the overall sample of 260 participants, acute outcome prevalence included CV in 20.1% and DCI in 46.6%. Long‐term outcome prevalence at 3 and 12 months included unfavorable GOS in 34.4% and 26.6%, and death in 18.7% and 23.1%, respectively. Significant associations were identified between cg08866780 and favorable GOS at 3 and 12 months (p = 0.005 and p = 0.0005, respectively) and survival at 3 and 12 months (p = 0.002 and p = 0.0005, respectively). These results were consistent after correction for CTH with associations identified between cg08866780 and favorable GOS at 3 and 12 months (p = 0.003 and p = 0.01, respectively) and survival at 3 and 12 months (both, p = 0.02). The results of this study support a role for regulation of APP in cerebrovascular recovery following SAH and may offer potential as a biomarker or therapeutic target to improve outcomes. These findings should be replicated in a larger sample and may extend to traumatic SAH.
Support: F31NR017311, R01NR004339, R01NR013610
Keywords: Stroke, Group‐based trajectory analysis, Iron homeostasis, APP, Biomarker
DECOMPRESSIVE CRANIECTOMY IN RENAL FAILURE PATIENTS ARE ASSOCIATED WITH INCREASED POSTOPERATIVE COMPLICATIONS
University of Rochester Medical Center, Neurosurgery, Rochester, USA
Decompressive craniectomies and craniotomies are effective standard surgical interventions for evacuation of focal space occupying lesions associated with increased intracranial pressure. Outcomes after surgical intervention for traumatic brain injury may vary depending on particular patient populations. At our institution, we observed increased morbidity and mortality in renal failure patients. Given this observation, we sought out to further investigate this trend on a national level by reviewing a national surgical quality database, the American College of Surgeons National Surgical Quality Improvement Program (NSQIP). Craniectomy and craniotomy patients were identified and associations with renal failure were analyzed. We hypothesized patients with renal failure would be associated with worse outcomes in patients with intracranial hemorrhages. Two thousand nine hundred and sixteen adult patients who underwent craniectomy and craniotomy for intracranial hemorrhage were identified. Twenty‐eight patients among this group had associated acute renal failure. 75% of the patients with acute renal failure had an adverse event compared to 44.7% of patients who did not have acute renal failure. In addition, 35.7% of the acute renal failure patients had 30‐day mortality versus the 17.7% non‐acute renal failure patients. Our study characterized traumatic brain injury patients undergoing craniectomy and craniotomy for intracranial hemorrhage with acute renal failure that we recognize are a high‐risk group for increased postoperative complications and mortality.
Keywords: Intracranial Hemorrhage, Renal Failure, Traumatic Brain Injury, Craniectomy, Craniotomy
RELATIONSHIP BETWEEN MEASURES OF CEREBROVASCULAR REACTIVITY AND INTRACRANIAL LESION PROGRESSION IN ACUTE TBI PATIENTS
1University of Toronto, Neurosurgery, Toronto, Canada
2University of Cambridge, Anesthesia, Cambridge, UK
3University of Manitoba, Surgery, Winnipeg, Manitoba
Keywords: cerebral autoregulation, intracranial hemorrhage, traumatic brain injury
A10 Hypoxia / Ischemia
PREHOSPITAL MANAGEMENT OF TRAUMATIC BRAIN INJURY BY TRIGEMINAL NERVE STIMULATION
Feinstein Institute for Medical Research, Neurosurgery, Manhasset, USA
Keywords: trigeminal nerve stimulation, brain trauma, resuscitation, bioelectronic medicine
AUTOMATED QUANTITATIVE PUPILLARY LIGHT REFLEX IN COMATOSE CARDIAC ARREST FOR FAVORABLE OR UNFAVORABLE OUTCOME PROGNOSTICATION
University of Pittsburgh, Neurological Surgery, Pittsburgh, USA
Keywords: Cardiac, Pupillometer, Arrest, light, reflex
REMOTE ISCHEMIC PRECONDITIONING IMPROVES POST‐OPERATIVE RECOVERY FOLLOWING DECOMPRESSION OF DEGENERATIVE CERVICAL MYELOPATHY
1Krembil Research Institute, Toronto Western Hospital, Toronto, Canada
2University of Toronto, Neurosurgery, Toronto, Canada
Degenerative cervical myelopathy (DCM) is caused by degenerative changes to the discs and soft tissues of the cervical spine, which leads to chronic compression of the spinal cord. Surgical decompression (DEC) is the current standard of care for moderate to severe DCM, while effective in most cases, in a subset of patients neuroinflammation and ischemia reperfusion injury (IRI) hinder a return to baseline function resulting in suboptimal recovery. Remote ischemic preconditioning (RIPC) is a non‐invasive technique that uses transient ischemia distal to the site of injury to prepare the host for ischemic insult. In transplantation studies, RIPC has been shown to be a robust method of reducing IRI‐induced infarction and cell death. In this study, we posit that the application of RIPC prior to DEC will enhance neurological recovery through the amelioration of DEC‐induced IRI. To induce DCM in C57BL/6 mice, a polyether material was implanted underneath the C5‐6 laminae to cause progressive compression of the cord due to focal ossification. At 12‐weeks post‐implantation, animals either underwent: 1) hindlimb RIPC (3 × 5‐mins of ischemia; 5‐mins reperfusion) prior to DEC; or 2) DEC alone (n = 50, respectively). Acute (24‐hours post‐DEC) and chronic (5‐weeks post‐DEC) analysis of secreted plasma and spinal cord cytokines, apoptosis, and oxidative markers was completed, and locomotor outcomes were measured bi‐weekly using the CatWalk system. Acutely, RIPC resulted in a significant decrease of circulating and spinal cord cytokines relative to DEC alone (p < 0.05). Chronically, RIPC animals significantly outperformed both DEC and DCM groups in multiple Catwalk metrics including body speed, stride length, cadence, and swing speed (p < 0.05). In conclusion, RIPC when performed prior to DEC, results in the reduction of several IRI hallmarks and confers robust long‐term neurological recovery relative to DEC alone. As a non‐invasive procedure, RIPC can complement DEC for rapid translation into the clinic.
Keywords: degenerative, cervical, myelopathy, preconditioning
A11 Imaging
LONGITUDINAL FUNCTIONAL NETWORK CHANGES AFTER CHRONIC TRAUMATIC BRAIN INJURY
1Centre for Neuro Skills Clinical Research and Education Foundation, Bakersfield, USA
2University of California Los Angeles, Neurosurgery, Los Angeles, USA
3University of California Los Angeles, Neurology, Los Angeles, USA
We report on data from an ongoing longitudinal study of TBI subjects designed to investigate network disruptions and cognitive performance during the time period of admission to rehabilitation (M = 50 weeks following injury), the discharge period (4‐27 weeks later), and 6 months following discharge.
Keywords: TBI, longitudinal, resting state fMRI
POSITIVE ASSOCIATION BETWEEN FRACTIONAL ANISOTROPY AND MEMORY DEFICITS IN MILD ACUTE TRAUMATIC BRAIN INJURY
1Brain Injury Research Lab, Minneapolis, USA
2Hennepin Healthcare, Neurosurgery, Minneapolis, USA
3Hennepin Healthcare Research Institute, Minneapolis, USA
4Department of Radiology, University of Minnesota, Minneapolis, USA
5Department of Neurosurgery, University of Minnesota, Minneapolis, USA
Keywords: diffusion properties, acute TBI, mild TBI
SUBDURAL HEMATOMA AND TRAUMATIC MENINGEAL ENHANCEMENT AFTER TRAUMATIC BRAIN INJURY
1HJF/CNRM, Bethesda, USA
2NIH/NINDS, Bethesda, USA
Subdural hematoma (SDH) is a known complication of patients presenting with acute traumatic brain injury (TBI). Traumatic meningeal enhancement (TME) is an imaging marker related to injury of the meninges (Roth et al., 2014), occurring in approximately 45% of the TBI population imaged acutely (Chiara Ricciardi et al., 2017). There has been little to no research into correlation of SDH presence and outcome when TME is present on acute imaging. To investigate the relationship between SDH and TME in acute TBI, a retrospective review of subjects enrolled into an IRB approved TBI natural history study (NCT01132937) at level 1 and level 2 trauma centers in the Washington, DC area was completed. Subjects included in this analysis had acute CT and research MRI (within 48 hours of injury) including gadolinium based post‐contrast FLAIR sequences. Imaging was compared among CT and MR imaging findings relating to SDH and TME. Statistical analyses included chi‐square. Of 641 subjects enrolled, 489 had both an acute CT and a post‐contrast MRI within 48 hours of injury. 109 (22.2%) were positive for SDH by CT and/or MRI (CT only:10, MRI only:45, both:54). Demographics of the SDH population were not statistically different from the SDH negative population: median (IQR) age 45 (30‐58); male 79 (72%); Caucasian 61 (56%); GCS(13‐15) 93(85%). 55% (271/489) were TME positive, with TME observed in 94% (102/109) of those with SDH. 3.2% (7/218) of TME negative population was SDH positive, with 1.4% (3/218) SDH positive on both CT and MRI (CT only:2, MRI only:2). Chi‐square test showed a strong association between SDH and TME (Pearson coefficient 82.67, p < 0.0001). These data suggest that acute MRI identifies approximately twice as many TBI subjects with SDH than CT alone, and that within 48 hours of injury there is an association between the presence of TME and of SDH. Additional longitudinal analyses are needed to determine whether TME is predictive of outcomes in the SDH population.
Keywords: Traumatic Meningeal Enhancement, Subdural Hematoma
SCALP HEMATOMA PREDICTS TRAUMATIC MENINGEAL INJURY IN ACUTE TRAUMATIC BRAIN INJURY
1Center for Neuroscience and Regenerative Medicine, Bethesda, USA
2Johns Hopkins Suburban Hospital, Bethesda, USA
3NINDS/NIH, Bethesda, USA
The most frequent finding on MRI in patients presenting to the emergency department with acute head injury is post‐contrast traumatic meningeal enhancement (TME), which suggests damage to the meninges. Patients may present with a scalp hematoma conspicuous on MRI, indicating the extracranial location of impact. This analysis explores the relationship between evidence and location of blunt‐force head trauma and the presence and location of TME. This is a retrospective review of patients enrolled in the NINDS THINC study from 2017‐2018 who had MRI within 48 hrs of injury that included T2‐FLAIR imaging before and after administration of gadolinium based contrast agent. Images were reviewed for presence and location of i) TME and ii) scalp hematoma. Statistical analysis was performed by Chi‐Square. Of the 80 subjects [46 males; age 46(IQR:30,60), mean GCS 15, mean time to MRI 17.5 hours]; 33 (41%) had scalp hematoma and TME, 18 had only TME, 7 had only scalp hematoma, and 22 had neither TME nor scalp hematoma (Pearson coefficient 12.2, p < 0.001). For subjects with both scalp hematoma and TME, localization of TME along the convexity was seen contrecoup (opposite) to the site of impact in 12/33 (48%) and coup in 10/33 (30%), 3 both coup and contrecoup, and 8 located only in the falx. Excluding the falx cerebri, TME was seen along the convexity in 63% of patients with a scalp hematoma compared to 25% of those without, p < 0.001. In TBI patients presenting within 48 hours of injury, patients with scalp hematoma were likely to have TME (83% PPV). However, TME was also observed in patients without scalp hematoma, particularly in the falx. Coup versus contrecoup patterns of TME in relation to scalp hematoma were equally likely to occur. Scalp hematoma suggests TBI patients are more likely (PPV = 0.83) to have injury to the meninges along the convexity in a coup, countercoup pattern.
Keywords: MRI, Flair, TME, Meninges
OPTIMIZING THE ACCURACY OF CORTICAL VOLUMETRIC ANALYSIS IN TRAUMATIC BRAIN INJURY
1Massachusetts General Hospital, Boston, USA
2Mount Sinai, New York, USA
3University of Washington, Seattle, USA
Cortical volumetric analysis is widely used to study the neuroanatomic basis of post‐traumatic cognitive and functional deficits. However, the application of this technique to patients with cortical lesions has been limited because lesions may compromise the accuracy of cortical surfaces. Here, we propose a novel FreeSurfer‐based lesion correction method and test its impact on cortical volumetric measures in 20 patients with chronic moderate‐to‐severe traumatic brain injury (TBI). MRI was performed at ≥1 year post‐injury using a T1‐weighted multi‐echo MPRAGE sequence at 1 mm resolution. We measured cortical gray‐matter (GM) volume within an atlas‐based limbic network whose fronto‐temporal nodes are often affected by contusions. For the pre‐correction analysis, we measured limbic network GM volume produced by FreeSurfer's standard pipeline. Next, to correct for lesion‐induced surface inaccuracies, we parcellated each hemisphere surface into 642‐faced polyhedra. Then, we manually labeled all sites of lesion overlap with the cortical surface on the polyhedra. If the limbic network appeared anatomically inaccurate at a site of lesion overlap, we removed the intersecting sub‐region of the polyhedra from the network. For the post‐correction analysis, we reran FreeSurfer's tools to measure the total GM volume based on the updated limbic network. Finally, we calculated the difference in limbic network cortical volume in the pre‐ versus post‐correction analyses. Fourteen of 20 TBI patients (70%) had lesions that involved limbic network nodes. Of the patients with limbic lesions, all but one had cortical surfaces that appeared anatomically inaccurate in the pre‐correction analysis. Of these thirteen patients, the mean+/‐SD limbic network cortical volume measures in the pre‐ versus post‐correction analyses were 44,104+/‐4,340 mm3 and 37,073+/‐6,937 mm3, respectively. Our lesion correction method thus led to a 15.9% change in cortical volume within the limbic network (p = 0.002). This proposed FreeSurfer‐based lesion correction method has the potential to increase the accuracy of cortical volumetric measurements in patients with TBI.
Keywords: MRI, cerebral cortex, encephalomalacia, neurodegeneration
DIFFUSION TENSOR IMAGING AND QUANTITATIVE SUSCEPTIBILITY MAPPING IN CONCUSSED ADOLESCENTS WITH AND WITHOUT PERSISTENT SYMPTOMS
1Medical College of Wisconsin, Neurosurgery, Milwaukee, USA
2Medical College of Wisconsin, Biomedical Engineering, Milwaukee, USA
3Medical College of Wisconsin, Radiology, Milwaukee, USA
It is estimated that approximately 30% of pediatric concussion patients develop persistent post‐concussion symptoms (PPCS), though the exact etiology of PPCS has not been determined. We explored the effects of concussion and PPCS in adolescents on deep gray and white matter brain structures using diffusion tensor imaging (DTI) and quantitative susceptibility mapping (QSM). Concussed adolescents with (PPCS; n = 28, 10 male, age = 16.09 ± 0.98) and without PPCS (Recovered; n = 15, 8 male, age = 15.93 ± 0.96) were recruited from a concussion clinic and completed visits at least one‐month post‐injury. Matched adolescents without prior concussion were recruited as healthy controls (HC; n = 15, 6 male, age = 16.25 ± 1.16). DTI and QSM were collected on a 3T GE scanner. Fractional anisotropy (FA), mean diffusivity (MD) and magnetic susceptibility were calculated in each participant using regions‐of‐interest (ROIs) derived from the Harvard‐Oxford and JHU‐ICBM atlases, with a priori analyses focused on caudate, putamen, pallidum, thalamus, corpus callosum, and internal capsule. Analysis of variance was used to determine group differences in FA, MD, and susceptibility. There were significant group differences in MD in bilateral putamen and right caudate (ps <0.05). Follow‐up tests found that MD in left and right putamen was significantly elevated in PPCS relative to HC (ps <0.05), whereas MD in the right caudate was lower in PPCS relative to HC (ps <0.05). No differences between groups were found in FA (ps >0.05). Groups also differed in magnetic susceptibility in the genu and body of the corpus callosum (ps <0.05), where PPCS had greater susceptibility relative to HC (ps <0.05). Ongoing analyses are investigating the relationships between diffusion metrics and magnetic susceptibility in the identified ROI. These pilot results suggest that DTI and QSM identify pathophysiology associated with PPCS in adolescent patients with concussion.
Keywords: Persistent post‐concussion symptoms, Diffusion tensor imaging, quantitative susceptibility mapping, Quantitative susceptibility mapping, Adolescents
THE EFFECTS OF CONCUSSION HISTORY AND CUMULATIVE CONTACT SPORT EXPOSURE ON BRAIN MORPHOMETRY IN COLLEGIATE ATHLETES.
1Medical College of Wisconsin, Milwaukee, USA
2University of California, Los Angeles, USA
3Mind Research Network, Albuquerque, USA
4Indiana University, Indianapolis, USA
5Indiana School of Medicine, Indianapolis, USA
6Virginia Tech, Blacksburg, USA
7University of North Carolina, Chapel Hill, USA
8University of Michigan, Ann Arbor, USA
There is growing concern that sport‐related concussion and contact sport participation may negatively affect brain structure and function. We investigated the independent effects of prior concussion and contact sport participation on brain morphometry in a large sample of active collegiate contact sport athletes (n = 190) and non‐contact controls (n = 95). Athletes completed up to four neuroimaging sessions across a 6‐month period. FreeSurfer 5.3 longitudinal pipeline quantified subcortical volumes and cortical surface metrics. Linear mixed‐effects models examined the effects of years of sport participation in contact and non‐contact athletes and number of prior concussions in contact athletes on morphometry. A priori subcortical analyses included bilateral thalamus, hippocampus, amygdala, and dorsal striatum, controlling for intracranial volume. Vertex‐wise spatiotemporal mass‐univariate models assessed cortical thickness and volume. There was a significant effect of concussion history on hippocampal volume in contact athletes (p = 0.037), with smaller hippocampal volumes in athletes with no prior concussion relative to those with 2 or more (p < 0.05). There was a significant interaction between years of sport participation and sport group (i.e., contact versus non‐contact) on thalamic volume (p = 0.015), with years of sport participation inversely correlating with thalamic volumes in contact athletes (p = 0.007), but not non‐contact athletes, (p = 0.27). There was a similar marginally significant interaction on hippocampal volume (p = 0.081). Follow‐up analyses demonstrated that the observed interactions were driven predominantly by football players (ps <0.01). There were no effects of concussion history or exposure on cortical thickness/volume. Findings suggest prior concussion and contact sport exposure have distinct effects on subcortical structures. Further research is needed to understand potential clinical implications, if any.
Keywords: Sport‐Related Concussion, Contact Sport, Brain Morphometry, CARE Consortium
FUNCTIONAL REORGANIZATION OF THE AGING BRAIN DECADES AFTER A CONCUSSIVE EVENT
National Institute on Aging, National Institutes of Health, Laboratory of Behavioral Neuroscience, Baltimore, USA
While recent studies have reported functional alterations of the brain shortly after a concussive event, few have examined long‐term effects on the aging brain. Here, we examine brain activation patterns, 20+ years after the concussive event. We used neuroimaging and neuropsychological data from 15 participants (mean age at neuroimaging baseline = 66.92, SD = 7.47) in the Baltimore Longitudinal Study of Aging (BLSA) who reported a concussion in their medical history an average of 22 years prior to first visit, and compared them to 30 age, sex, and race matched BLSA participants with no history of concussion. Participants underwent 15O‐water Positron Emission Tomography (PET) scans to measure brain activation patterns over a mean of 6.64 years (SD = 2.22) and neuropsychological testing over a mean of 11.62 years (SD = 7.41). Verbal and figural (spatial) memory recognition tasks were performed during scanning. No significant differences (p < 0.05) were seen between groups in verbal and figural memory PET task performance levels over time, nor in overall verbal and spatial cognitive performance on neuropsychological tests. During both memory scans, the concussion group showed greater activity in right frontal and temporal brain regions at first visit (p < 0.005, 50 voxels). During an additional 6‐year span, the concussion group continued to increase activation in these right hemisphere regions, while subcortical and posterior left hemisphere regions decreased over time. These differences in blood flow were also correlated with better verbal and spatial cognitive performance within the concussion group itself on tasks involving verbal fluency, verbal memory, and spatial memory (p < 0.05). The differences in brain activity between concussed and non‐concussed groups suggest that compensatory mechanisms may help maintain cognitive abilities in those with prior concussion. However, these individuals may be more vulnerable to future cognitive decline if the compensatory mechanisms fail. This research was supported by the Intramural Research Program of the National Institute on Aging, National Institutes of Health.
Keywords: Functional Imaging, Aging, Cognition, Concussion
RESTRICTED DIFFUSION IMAGING : A NOVEL ALGORITHM TO STUDY MICRO‐STRUCTURAL CHANGES AFTER BRAIN INJURY
1The Ohio State University, Neurosurgery, Columbus, USA
2University of Pittsburgh, Neurosurgery, Pittsburgh PA, USA
Keywords: brain injury, diffusion weighted imaging, brain ablation
ADMISSION LEVELS OF SERUM NF‐L ARE ASSOCIATED WITH LATER MRI SIGNS OF AXONAL INJURY IN MILD TBI
1Turku University Hospital, Brain Injury Center, Turku, Finland
2University of Cambridge, Department of Clinical Neurosciences, Neurosurgery Unit, Cambridge, UK
3University of Cambridge, Division of Anaesthesia, Cambridge, UK
4Turku University Hospital, Department of Radiology, Turku, Finland
5University of Turku, Turku Brain and Mind Center, Turku, Finland
6Sahlgrenska University Hospital, Clinical Neurochemistry Laboratory, Gothenburg, Sweden
7University of Geneva, Department of Specialities of Internal Medicine, Geneva, Switzerland
Keywords: DTI, mild TBI, NFL
ASSESSING FUNCTIONAL CONNECTOMIC MEASURES IN ANIMAL MODELS OF TBI USING HIGH‐FIELD RESTING‐STATE FMRI
1University of Florida, Psychiatry, Gainesville, USA
2University of Florida, Emergency Medicine, Gainesville, USA
3University of Florida, Anesthesiology, Gainesville, USA
4Malcom Randall VA Medical Center, Gainesville, USA
TBI‐induced diffuse axonal injury (DAI) can produce brain‐wide functional connectivity disruptions. Here we used high field resting‐state fMRI (rsfMRI) and brain‐wide functional connectivity analysis to measure intrinsic resting state neural activity between sensory, motor, affective and cognitive brain areas after controlled cortical injury (CCI) or fluid‐percussive injury (FPI). Adult male rats were imaged on a 11.1‐Tesla MRI scanner controlled by Bruker Paravision 6.0.1 under 1.5% isoflurane at Day 2 and at Day 30 post‐injury. Respiratory rate was monitored continuously, and body temperature was controlled. fMRI scans were collected using a single‐shot spin echo planar imaging sequence [TE = 15ms, TR = 2sec, 300 repetitions, field of view = 24x18mm, data matrix = 64x64x25, slice thickness = 0.9mm]. A high‐resolution turbo rapid acquisition with relaxation enhancement was used for functional image overlays and alignment with a segmented atlas of rat brain. We employed both manual‐drawing‐assisted seed‐based functional connectivity analysis, and atlas‐based seed localization. Manual seed analysis indicates a diffuse disruption of connectivity in ipsilateral hippocampus and somatosensory cortex in CCI/FPI animals relative to controls. This was consistent with the atlas‐based analyses. We further conducted connectomic metric analysis and observed clear suppression of connectivity patterns, which was most robust in CCI relative to controls. Standard anatomical MRI in TBI is limited in terms of the characterization of functional network properties. High field functional connectivity can help fill this gap and provide markers reflecting functional deficits, progression and potential treatment responses.
Keywords: Functinal connectivity, Resting state fMRI, High field imaging, Network analysis, Controlled cortical injury, Fluid percussive injury
FREE‐WATER IMAGING FINGERPRINTING OF TRAUMATIC BRAIN INJURY
Ragini Verma2, William Andrew Parker2, Jacob Anthony Allapatt2, Abdol Aziz Ould Ismail2, Margalit Haber1, Carol Moore1, Kimbra Kenney2,
1University of Pennsylvania, Department of Neurology, Philadelphia, USA
2University of Pennsylvania, Department of Radiology, Philadephia, USA
3Uniformed Services University, Department of Neurology, Bethesda, USA
Keywords: Diffusion imaging, Free water fraction
VOLUMETRIC MR IMAGING AS A BIOMARKER FOR COGNITIVE DECLINE IN MILD TRAUMATIC BRAIN INJURY
University of Pittsburgh, Pittsburgh, USA
Keywords: MR Volumetrics in mTBI
MRI SCANNING PRACTICES IN CHILDREN WITH SEVERE TBI
1University of Pittsburgh, Department of Epidemiology, Pittsburgh, USA
2Children's National Health System, Washington, District of Columbia, USA
3University of Wisconsin, Madison, USA
Keywords: MRI, Imaging, TBI
IMAGE‐GUIDED NEUROPATHOLOGICAL TISSUE SECTIONING FOR TRAUMATIC BRAIN INJURY RESEARCH
1University of Washington, Neurological Surgery, Pathology, Seattle, USA
2Massachusetts General Hospital, Neurology, Boston, USA
3Icahn School of Medicine at Mount Sinai, Rehabilitation, New York City, USA
A historical challenge with human brain tissue examination of traumatic brain injury (TBI) has been that injuries are heterogeneous, leaving considerable debate as to how to systematically sample the tissue. We have attempted to address this problem by developing standardized brain specimen preparation techniques including systematic embedding, slicing, and sectioning strategies not traditionally utilized by pathologists. The goal of the study was to design new methods that provide a standardized approach while also integrating sectioning strategies that are flexible to TBI heterogeneity. Exvivo MRI allowed for identification of lesions not visible on the gross tissue pathology. Image‐guided tissue sectioning of pathoanatomic lesions supplemented standardized sectioning. Incorporating exvivo imaging into this neuropathology protocol not only enhanced the brain tissue sectioning but also allowed for coregistration with ante‐mortem imaging. This coregistration has yielded insights into the evolution of lesions previously identified in life and the resultant injury pathology discovered after death. Longitudinal clinical data available on a subset of cases permits identification of phenotypic correlates of injury pathology. We have employed these methods on 22 TBI brains for neuropathological examination. Results repeatedly showed an increase in the identification of brain injury pathology relative to that identified using a standard neurodegenerative disease sectioning protocol, and in some cases alteration in final post mortem diagnosis. As the neurotrauma community expands the procurement of brain donations for TBI research, systematic protocols are needed to standardize this approach in a way that is generalizable and conducive to data sharing. We present this image‐guided tissue sectioning technique and the preliminary results of these neuropathological examinations as one such approach. This protocol can be employed by the neurotrauma community to capture meaningful data from these precious tissue samples in a standardized fashion allowing for comparison across decedents, diagnoses, and research sites.
Keywords: Traumatic Brain Injury, Neuropathology, Exvivo Imaging, White Matter Injury
PREFRONTAL MODULATORY FUNCTIONAL CHANGES AFTER RTMS IN MTBI PATIENTS WITH HEADACHES
Valerie Metzger‐Smith1, Michael Vaninetti1,2, Mike Lim1, Aladdin Khalaf1, Eric Yang1, David Song1,2, Lisa Lin1, Alice Tsai1, Roland Lee1,2, Albert Leung1,2,
1VA San Diego Healthcare System, Center for Pain and Headache Research, San Diego, USA
2UC San Diego, Medical Campus, San Diego, USA
Keywords: TBI, Imaging, Headache, TMS
A12 Neurocritical Care
DIFFERENT HOSPITAL, DIFFERENT INTERVENTION? PREDICTORS OF SURGICAL INTERVENTION AND OUTCOMES IN TRAUMATIC SPINAL CORD INJURY
Duke, Departments of Neurosurgery, and Biostatistics & Bioinformatics, Duke University Medical Center, Durham, USA
The effects of trauma center level on traumatic spinal cord injury (SCI) management are not well‐characterized. The primary objective of this retrospective study was to determine the effect of trauma hospital level (I vs. II/III/IV) on incidence of surgical intervention in patients with traumatic SCI in the US. The secondary objective included examining the effect of trauma center level and inter‐hospital transfer on timing of surgical intervention. The NTDB database was used to identify adult patients diagnosed with traumatic SCI between 2010‐2015 without concurrent traumatic brain injury. Early surgical intervention was defined as surgery performed within 24 hours after hospital arrival. Logistic regression models were fit to examine the relationship between variables trauma center level and inter‐hospital transfer and incidence and timing of surgical intervention. We controlled for clinical factors such as abbreviated injury score for spine injury severity. Of 18461 traumatic SCI patients identified, 7883 (42.7%) had surgical interventions and 3955 (21.4%) had early surgeries. Patients directly admitted to a level I trauma center had higher odds of receiving surgeries than those directly admitted to level II/III/IV centers (OR = 1.35, p < 0.001), as well as higher odds of receiving early surgeries (OR = 1.26, p = 0.004). Amongst patients in level I trauma centers, inter‐hospital transfer did not affect the incidence of surgical intervention (OR = 0.95, p = 0.20), nor the timing of surgical intervention (OR = 0.90, p = 0.09). Among patients in level II/III/IV centers, patients transferred in had a higher likelihood of getting a surgery (OR = 1.16, p = 0.02), but inter‐hospital transfer did not affect the timing of surgical intervention (OR = 1.19, p = 0.07).
Compared to traumatic SCI patients directly admitted to level II/III/IV centers, patients directly admitted to level I trauma centers were more likely to receive surgical intervention and to receive the procedure within 24 hours of hospital arrival. Inter‐hospital transfer had a significant effect on surgical intervention in level II/III/IV centers, but not in level I centers. Award# UL1TR002553
Keywords: spinal cord injury, trauma center level, surgical intervention, inter‐hospital transfer
ASSESSING METABOLIC REQUIREMENTS OF TBI PATIENTS DURING ICU BY NITROGEN BALANCE
Seoul National University Hospital, Neurosurgery/Neurocritical Care, Seoul, Korea South
Keywords: Nitrogen balance
NEUROPROTECTIVE ROLE OF DRAG REDUCING POLYMERS ADDITIVE TO HETASTARCH RESUSCITATION FLUID FOR TBI WITH HEMORRHAGIC SHOCK
1University of New Mexico, Albuquerque, USA
2University of Pittsburgh, Pittsburgh, USA
Keywords: TBI, Hemorhagic Shock, Resuscitation, Hemorheological Approach, Neuroprotection, Hetastarch
EFIC COMMUNITY CONSULTATION AND PUBLIC DISCLOSURE: THE BOOST‐3 PITTSBURGH EXPERIENCE
University of Pittsburgh, Neurosurgery, Pittsburgh, USA
Keywords: acute care research, exception from informed consent, community consultation, public disclosure
INTER‐RATER RELIABILITY ASSESSMENT OF THE NEUROIMAGING COMMON DATA ELEMENTS FOR MRI IN SEVERE PEDIATRIC TBI
1University of Wisconsin, Pediatrics, Madison, USA
2University of Wisconsin, Waisman Center, Madison, USA
3University of Pittsburgh, Epidemiology, Pittsburgh, USA
4University of Wisconsin, Radiology, Madison, USA
5Children's National Health Systems, Critical Care Medicine, Washington, DC, USA
6University of Texas, Population Health, Austin, USA
Keywords: Neuroimaging, Traumatic Brain Injury, Common Data Elements
MRI VOLUMETRIC MEASURES OF FUNCTIONAL OUTCOME AFTER SEVERE PEDIATRIC TBI
1University of Wisconsin, Waisman Center, Madison, USA
2University of Pittsburgh, Psychiatry, Pittsburgh, USA
3University of Pittsburgh, Epidemiology, Pittsburgh, USA
4Brigham Young University, Psychology, Provo, USA
5Seattle Children's Hospital, Psychiatry, Seattle, USA
6Children's National Health Systems, Critical Care Medicine, Washington, D.C., USA
7University of Texas, Population Health, Austin, USA
Keywords: TBI, MRI, VBR, Corpus Callosum
ASSOCIATIONS OF MORTALITY IN MULTIPLE SIGNIFICANT TRAUMA WITH CRANIOTOMY: A NATIONWIDE INPATIENT SAMPLE ANALYSIS
UT Health San Antonio, Long School of Medicine, San Antonio, USA
Keywords: Craniotomy, Multiple Significant Trauma, Nationwide Inpatient Sample, Mortality, Socioeconomic Factors, Teaching Hospitals
CHALLENGES TO NEUROTRAUMA CARE IN THE DEVELOPING WORLD: A VIETNAMESE PERSPECTIVE
1Wake Forest Baptist Health, Dept of Neurology and Neurocritical Care, Winston‐Salem, USA
2Wake Forest School of Medicine, Winston‐Salem, USA
The incidence of neurotrauma, particularly, severe traumatic brain injury in low and middle income countries is on the rise and makes up the bulk of trauma the world over, with road traffic related accidents and injuries being the major contributor. Saigon in Vietnam is a typical example of a densely populated city with a high congestion of two‐wheeler traffic and minimal to no head protection worn by motorists and incidentally. While the incidence is high, the health system is overwhelmed and ill‐equipped to deal with this burden. Numerous barries exist to delivery of care. A 6‐year association with the largest trauma center in the city has given us a better understanding of the specific obstacles and challenges to delivering effective neurocritical care to the trauma victim. We examine the important components of care that are lacking, including: weak emergency transport to the hospital, polonged times to triage, lack of basic hemodynamic monitoring, financial limitations and models preventing appropriate care, allied health care shortage, barriers in language, education, and training that prevent effective medical care, little to no neuromonitoring, shortage of ventilators and respiratory therapists, skewed work structure and physician schedules, complete lack of outcomes information and finally, little to no research or local epidemiological information or accountability. The goal of an interaction is to help with capacity building, innovate to overcome restrictions, motivate physician attitudes for change, develop simple treatment protocols and encourage measuring outcomes. Our efforts are aimed at implementation science and quality help from developed western systems of neurocritical care that can be transferred to settings like Saigon.
Keywords: Developing world, low and middle income countries, LMIC
PILOT PROJECT OF CLINICAL PROCEDURES FOR FIRST YEAR MEDICAL STUDENTS IN CADAVERIC SPECIMENS
Wayne State University School of Medicine, Detroit, USA
Severe traumatic brain injury often requires several immediate procedures such as ventriculostomy or emergency cricothyrotomy. Clinical procedures introduced in the gross lab during the first year of medical school may help students learn anatomical landmarks, create more enthusiasm in students' dissections, and impart basic familiarity with clinical procedures. Medical students in their third and fourth year are expected by the AAMC to master a number of clinical procedures. A philosophy in some hospitals is “see one, do one, teach one”. Year 1 medical students (n = 296) were emailed video links and given stepwise instructions on how to perform nasogastric (NG) tube insertion and emergency cricothyrotomy as part of the CNS unit. Upperclassmen (Supplemental Instructional Leaders) taught the lowerclassmen how to conduct these procedures on cadavers. Students appeared enthusiastic in performing these techniques even though the timing was not ideal (last 2 labs before exams). It required 10‐20 minutes to complete the procedures. Costs were minimal as the NG and intubation tubes could be used on several cadavers. Surveys that included requests for comments to obtain qualitative data were sent to first year medical students. Seventy percent (40/57) responded that this was a valuable educational experience and sixty‐four percent (36/56) answered that this helped them learn anatomical landmarks. Ninety percent (54/60) responded that more basic clinical procedures should be done as part of the first year curriculum. Most students had positive comments about the experience. Students mentioned that practicing these procedures in a controlled and low pressure setting will allow them to be more confident during their clerkships as well as reinforcing crucial information and anatomical landmarks. Based on our experience with these two clinical procedures, implementation of the basics of clinical procedures is a worthwhile endeavor. Other clinical procedures that might be useful include lumbar punctures, endotracheal intubation, and suturing. Supported by Wayne State School of Medicine.
Keywords: education, cricothyrotomy, medical students, survey, Critical care, Teaching
A13 Neuropathology
PARAMETER OPTIMIZATION OF EPIDURAL SPINAL CORD STIMULATION TO RESTORE VOLITIONAL MOVEMENT AFTER CHRONIC MOTOR‐COMPLETE INJURY
1UMN, BME, Minneapolis, USA
2UMN, Department of Neurosurgery, Minneapolis, USA
3HCMC, Department of Neurosurgery, Minneapolis, USA
4UMN, ECE, Minneapolis, USA
Epidural spinal cord stimulation (eSCS) has been reported to partially restore volitional movement and autonomic function for patients with chronic motor‐complete spinal cord injury (SCI). Existing eSCS systems tout a nearly infinite number of possible temporal and spatial patterns of stimulation, and the possible or adverse effects of eSCS span all organ systems, which produces a challenging global optimization problem. Significant heterogeneity of function after SCI has prompted a personalized approach to optimization. Therefore, we were motivated to create an optimization strategy capable of capturing effects spanning basic physiology to functional outcomes as well as from voluntary movement to autonomic function using remotely collected data for the E‐STAND trial. We developed a novel probit Bayesian optimization platform that leverages quantified patient preference data to efficiently search for optimal stimulation parameters. Routine reprogramming sessions and research visits allow new parameters to be regularly included and remotely evaluated via mobile application daily for binary comparison. Probabilistic value function is fit to all the tested settings that maximize the likelihood of preference observations. A simple one minute daily survey provides the necessary comparisons each month to estimate a cumulative probit model. Bayesian optimization identifies next settings to evaluate for incremental optimization while simultaneously provide multi‐outcome optimal parameter space maps. Out of seven patients (4 male, 3 female) with ages ranging from 30‐65 years old, and 4‐17 years from injury, two patients have completed the 15 month long study. Averagely, patients complete 45 binary comparisons each program month. Currently, the first seven patients have converged on a range of frequencies between 20 and 45 Hz after exploring from below 20 Hz to more than 600 Hz. Parameter optimization for function restoration with eSCS after SCI has revealed frequency‐dependence and relative pulse‐width or duty cycle independence across patients.
Keywords: machine learning, autonomic, spinal cord stimulation, volitional control
INCREASED SUSCEPTIBILITY TO TRAUMATIC BRAIN INJURY AND ASSOCIATED WHITE MATTER DAMAGE IN AGED MICE
1IRCCS‐Mario Negri Institute for Pharmacological Research, Department of Neuroscience, Milan, Italy
2Fondazione Ca' Granda ‐ Ospedale Maggiore Policlinico, Department of Anesthesiology and Intensive Care, Milan, Italy
3Fondazione IRCCS ‐ Istituto Neurologico Carlo Besta, Milan, Milan, Italy
4University of Cambridge, Division of Anaesthesia, Department of Medicine, Cambridge, UK
Traumatic brain injury (TBI) shows a second peak of incidence in the elderly and is associated with worse outcome. The mechanisms underpinning the higher susceptibility to progressive neurological deterioration and neurodegeneration are uncertain. We aim at understand whether a distinct aged dependent inflammatory response may contribute to increased brain dysfunction and white matter damage in the elderly. Adult (8 weeks old) and aged (18 months) mice were subjected to sham, moderate (m) or severe (s)TBI by controlled cortical impact. Sensorimotor deficits were assessed weekly by neuroscore and Simple Neuroassessment of Asymmetric imPairment (SNAP). TBI aged, showed greater sensorimotor deficits than adult mice, with mTBI in the elderly producing a degree of functional impairment similar to that observed in adult sTBI mice. We found a high correlation between SNAP at 1 week and contusion volume in young and aged mice assessed by magnetic resonance imaging (MRI). Functional deficits at 6 weeks only correlated with contusion volume in aged mice, suggesting a higher recovery potential in the young. MRI analysis showed a decreased fractional anisotropy in the ipsilateral white matter with an injury‐severity dependent effect both in adult and aged mice. Axial, radial and mean diffusivity were increased only in aged sTBI mice. Histopathology showed similar neuronal damage in the pericontusional cortex across ages, but an increased glial activation in aged compared to young sTBI mice. Notably, increased microgliosis was observed exclusively in the lesioned cortex while astrogliopathy was widespread involving white matter and contralateral brain structures thus suggesting a major contribution of astroglial activation in driving neurological dysfunction in the elderly.
Keywords: traumatic brain injury, susceptibility, aging, neuropathology
DEFINING INJURY TYPES OF NEURO‐VASCULAR UNIT COMPROMISE IN THE RAT PERICONTUSED CORTEX AFTER CONTROLLED CORTICAL IMPACT
1UCLA, IDDRC, Los Angeles, USA
2UCLA, BIRC, Los Angeles, USA
Relating non‐invasive neuroimaging and blood‐based biomarkers to distinct stages and types of traumatic brain injury (TBI) promotes understanding and tracking of pathophysiologies that determine severity and outcome. Routine clinical imaging captures tissue loss/atrophy, but tissue wounding and functional compromise remain elusive, yet are critical for neurological function. This project establishes parameters of cytological pathophysiology in the pericontused cortex after rat controlled cortical impact (CCI). Astrocytes are essential players in the neuro‐vascular unit and their damage compromises cerebral function. We correlated novel Astrocyte Injury Defined (AID) biomarkers with cytological wounding and neuroimaging. Coronal vibratome sections were cut from CCI and sham brains at 5‐8hrs and 24hrs post‐injury. Sudan black‐blocked sections were immunostained for rat immunoglobulins (IgGs), aldolase C (ALDOC), glutamine synthetase (GS), GFAP, pan‐neurofilament (NF) and NeuN. Images of core and pericontused gray matter were captured highly systematically regarding cortical microanatomy and injury position. AID biomarkers, neuron and astrocyte structural changes and interstitial bleeding were objectively measured using thresholding, and structure‐capturing in ImageJ. Pericontused regions showed significant NeuN reduction versus sham and presence of IgG extravasation, which was elevated over sham (effect size <3) but lower than in injury cores (effect size >3). Total NF signal was significantly reduced in pericontusions compared to sham gray matter. Automated capturing of NF profiles by size and shape distinguished intact fibers (85% of sham NF), larger/aligned segments (34‐50% of pericontusion NF) and entirely disintegrated fibers (38‐44% of core NF). ALDOC and GS signals were reduced after CCI from sham in pericontusions of non‐hemorrhagic CCIs, but not in hemorrhagic‐type injuries. Yet, both TBI‐types had crippled astrocytes, documented by significant reduction in ALDOC and GS‐expressing astrocytes. Astrocyte process‐branching was reduced in pericontusions. This cyto‐metric data is correlated with MRI, and biofluid levels of AID biomarkers. Correlating brain tissue compromise with noninvasive diagnostic tools will facilitate translation and improve future treatment assessment for TBI patients.
Keywords: Neurovascular unit, pericontusion, neuronal‐glial interaction, axonal injury, imaging, histopathology
DEFINING INJURY TYPES OF NEURO‐VASCULAR UNIT COMPROMISE IN THE RAT PERICONTUSED CORTEX AFTER CONTROLLED CORTICAL IMPACT
University of California, Los Angeles, IDDRC, Los Angeles, USA
Relating non‐invasive neuroimaging and blood‐based biomarkers to distinct stages and types of TBI promotes understanding and tracking of pathophysiologies that determine severity and outcome. Routine clinical imaging captures tissue loss/atrophy, but tissue wounding and compromise remain elusive, yet are critical for neurological function. This project establishes parameters of cytological pathophysiology in the pericontused cortex, which has potential for recovery, after rat controlled cortical impact (CCI). Astrocytes are essential players in the neuro‐vascular unit and their damage compromises cerebral function. We correlated novel Astrocyte Injury Defined (AID) biomarkers with cytological wounding and neuroimaging. Coronal vibratome sections were cut from CCI and sham brains at 5‐8hrs and 24hrs post‐injury. Sudan black‐blocked sections were immunostained for rat immunoglobulins (IgGs), aldolase C (ALDOC), glutamine synthetase (GS), GFAP, pan‐neurofilament (NF) and NeuN. Images of core and pericontused gray matter were captured highly systematically regarding cortical microanatomy and injury position. AID biomarkers, neuron and astrocyte structural changes and interstitial bleeding were objectively measured using thresholding and structure‐capturing in ImageJ. Pericontused regions showed significant NeuN reduction versus sham. Pericontusional IgG extravasation was elevated over sham (effect size <3) but lower than in injury cores (effect size >3). NF signal was significantly reduced in pericontusions compared to sham gray matter. Automated capturing of NF profiles by size and shape distinguished intact fibers (85% of sham NF), larger/aligned segments (34‐50% of pericontusion NF) and entirely disintegrated beads (38‐44% of core NF). ALDOC and GS signals were reduced after CCI from sham in pericontusions of non‐hemorrhagic CCIs, but not in hemorrhagic‐type injuries. Yet, pericontusions of both TBI‐types had crippled astrocytes, documented by reduced process branching and a significant reduction in ALDOC and GS‐expressing intact‐sized astrocyte numbers. This novel cyto‐metric data is correlated with MRI, and biofluid levels of AID biomarkers. Associating brain tissue compromise with noninvasive diagnostic tools will facilitate translation and improve future treatment assessment for TBI patients. Support:NIH UG3NS106945 a TOP‐NT consortium‐project.
Keywords: Neurovascular unit, pericontusion, neuronal‐glial interaction, axonal injury, imaging, histopathology
IMPACT OF DIET‐INDUCED MODIFICATION OF NEURONAL PLASMA MEMBRANE LIPID COMPOSITION ON SUSCEPTIBILITY TO TBI‐INDUCED DAMAGE
1CMC VAMC, Center for Neurotrauma, Neurodegeneration & Restoration, Philadelphia, USA
2UPenn, Center for Brain Injury & Repair, Department of Neurosurgery, Philadelphia, USA
Traumatic brain injury (TBI) can compromise neuronal plasma membrane integrity. Susceptibility to biomechanically‐induced plasmalemmal damage and subsequent pathophysiology could be altered by changing plasma membrane properties. Stiffer structures are more likely to experience plasmalemmal tears versus more flexible structures. Because these properties are affected by plasmalemmal lipid composition, we evaluated the role of various lipids on biomechanically‐induced alterations in membrane integrity using rat lateral fluid percussion injury (FPI). For 4 weeks rats were fed control diet, 6% fish oil diet (FO) high in polyunsaturated fatty acids (PUFAs) to increase membrane flexibility, or high saturated fat and cholesterol diet (HF) to increase membrane rigidity. Changes in brain fatty acid (FA) composition were confirmed in a cohort of animals via gas chromatography‐mass spectrometry. FO increased the percentage of unsaturated FA (p ≤ 0.005) and decreased saturated FA (p ≤ 0.001) compared to other diets. FO increased omega‐3 PUFAs like docosahexaenoic acid (p ≤ 0.004) and eicosapentaenoic acid (p ≤ 0.0001), while HF increased omega‐6 docosapentaenoic acid (p = 0.002) compared to other diets. To examine changes in plasma membrane integrity, a separate cohort of animals received intraventricular injections of a small, cell‐impermeable fluorescent dye (Lucifer Yellow, LY). After 2 hours of diffusion, animals received FPI (2.1‐2.3 atm) or sham injury and were sacrificed immediately. FPI produced LY+ cells in cortex, subcortical regions, and especially hippocampus. To examine longer‐term outcomes, a third cohort of animals did not receive LY injections and instead were survived 7 days post FPI/sham to assess behavioral changes, neurodegeneration, and inflammation. The effects of diet‐induced plasma membrane composition on neuronal permeability, behavioral, and neuropathological changes are being correlated. These findings will suggest a role of dietary fat intake on neuronal susceptibility to acute damage and pathophysiology post‐TBI, and may lead to dietary guidelines for persons in fields with an increased incidence of TBI, such as military personnel and athletes.
Keywords: permeability, lipid, plasma membrane, diet
NEUROGRANIN NEURONAL PROTEIN EXPRESSION IS ALTERED AFTER CONTROLLED CORTICAL IMPACT
1University of Pittsburgh, Center for Neuroscience, Pittsburgh, USA
2University of Pittsburgh Medical Center, Department of Neurological Surgery, Pittsburgh, USA
3V.A. Pittsburgh Healthcare System, Pittsburgh, USA
Traumatic brain injury (TBI) is known to cause short and long‐term synaptic changes in the brain, possibly underlying downstream cognitive impairments. Neuronal levels of neurogranin, a calcium‐sensitive calmodulin‐binding protein essential for synaptic plasticity and postsynaptic signaling, are tightly correlated with cognitive function. Thus, it has been established as a synaptic biomarker for Alzheimer's disease and, more recently, TBI. This study aims to understand the role of neurogranin in synaptic dysfunction by characterizing changes in protein expression at various time points after TBI. Under isoflurane anesthesia, adult male Sprague Dawley rats (275‐300g; 6 per group) were subjected to either controlled cortical impact (CCI) to simulate a moderate‐to‐severe TBI (2.8mm deformation, 4m/s) or control surgery. Expression of neurogranin was evaluated by Western blot in the cortex and hippocampus at 24 hours, 1‐week and 2‐weeks post‐injury. Student t‐tests were conducted for each region compared to sham. At 24hrs, distinct regional changes in neurogranin levels were observed. Protein expression was significantly reduced in both the ipsilateral and contralateral hippocampus (p = 0.0095; p = 0.0087), however no change was observed in cortex. At 1 week, injury proximity drove changes in neurogranin. Lower protein levels were observed in the ipsilateral hippocampus and cortex (p = 0.0043; p = 0.0022), while the contralateral hemisphere showed no changes. The same expression pattern was observed 2 weeks post‐injury (p = 0.0381; p = 0.0411). Qualitative immunohistochemical assessment corroborated our western blot findings. Particularly, the peri‐contusional cortex and hippocampal CA3 region showed marked reduction in immunoreactivity. Our results indicate that CCI lowers neurogranin expression with both temporal and regional specificity. The ipsilateral cortex and hippocampus were vulnerable at all time‐points, as compared to the contralateral hemisphere. Further understanding of changes in synaptic biology will elucidate pathological mechanisms contributing to cognitive dysfunction after injury.
Support: NIH R01 NS106925 (CED) and subcontract (CED) to PA Department of Health PA Consortium on TBI grant #4100077083.
Keywords: neurogranin, post‐synaptic, controlled cortical impact, plasticity
SUBSET OF NEUN‐ MEMBRANE DISRUPTED NEURONS FOLLOWING BRAIN TRAUMA IN RATS
1Virginia Commonwealth University, Richmond, USA
2Godwin High School, Henrico, USA
Traumatic brain injury (TBI) has repercussions for years post‐injury. Studies indicate that these consequences stem from diffuse pathologies, however, there are still inquiries regarding TBI‐mediated diffuse pathologies, particularly, diffuse membrane disruption. Membrane disruption has been shown to occur acutely following injury, primarily within neurons, however, the progression of membrane disruption remains undefined. Therefore, the current study investigated this pathology out to 4w following central fluid percussion injury (CFPI) in adult male Sprague Dawley rats using intraventricular infusion of 10kDa cell‐impermeable fluorescently‐tagged dextran administered 2h before sacrifice at 6h, 1d, 3d, 1w, 2w or 4w (n = 5/group). The percentage of NeuN+ neurons demonstrating membrane disruption, via uptake of dextran in the lateral neocortex, layers V and VI, was quantified from 6h‐4w. Membrane disruption displayed a biphasic pattern, wherein over 40% of the population displayed membrane disruption from 6h to 3d (6h p = 0.000234, 1d p = 0.013 3d p = 0.012 vs. sham). At 1w, however, the membrane disrupted population was drastically reduced. At 2w and 4w, there was a resurgence of membrane disruption to approximately 50% of the total population (p = 0.000137 and p = 0.000098 respectively vs. sham). Moreover, our data revealed a subset of membrane disrupted cells that were NeuN‐. This subpopulation was significantly elevated at 2w post‐injury (p = 0.007 vs. sham). Correlative western blot analyses, however, revealed no difference in NeuN protein amount. Furthermore, NeuN‐ membrane disrupted cells did not co‐label with the astrocyte marker, GFAP, microglial Iba‐1, nor oligodendrocyte marker CC‐1/APC. Immunohistochemistry against NeuN, paired with a hematoxylin and eosin counter‐stain, was performed to quantify the possibility of overall NeuN+ cell loss following CFPI. A NeuN‐ population was observed consistently in both sham and injured animals regardless of time post‐injury. Therefore, these data suggest NeuN‐ neurons are specifically vulnerable to membrane disruption at 2w post‐injury. Understanding membrane disruption and specifically the NeuN‐ membrane disrupted subpopulation, could provide insight into the mechanisms of diffuse pathology following TBI. Funding: NINDS R01NS096143.
Keywords: traumatic brain injury, diffuse pathology, central fluid percussion injury, membrane disruption, NeuN
A14 Pain
PAIN INPUT AFTER SPINAL CORD INJURY INCREASES TISSUE LOSS AND IMPAIRS LONG‐TERM RECOVERY IN FEMALE RATS
1Texas A&M University, Psychological and Brain Sciences, College Station, USA
2Army Institute of Surgical Research, Battlefield Pain Research, San Antonio, USA
Spinal cord injuries (SCI) are often the result of traumatic accidents resulting in polytrauma. Pain input from associated injuries has been shown to impair locomotor recovery, increase hemorrhage, and expand the lesion site. Historically, this research has focused exclusively on male subjects, due to a higher prevalence of SCI in that population. However, increasing incidence of SCI in females requires research to determine if pain input poses the same risk to females and their recovery. Research has shown that females demonstrate greater tissue preservation and better locomotor recovery following SCI. Given this, we examined the effect of sex on SCI recovery in two pain models. In both experiments, female rats were given a moderate contusion at T12 and treated 24 hours later. In the first experiment, subjects received either six minutes of uncontrollable intermittent electrical stimulation to the tail or none at all. In the second experiment, animals received an intradermal injection of the peripheral irritant, capsaicin (3%), or its vehicle to the hindpaw. After both treatments, blood pressure and BBB locomotor scores were evaluated at 0, 1, 2, and 3 hours. Animals were then sacrificed and a one‐centimeter section of spinal tissue centered on the lesion site was collected for protein extraction. Protein samples were analyzed for signs of hemorrhage using spectrophotometry and immunohistochemistry. Any pain input, either electrical stimulation or capsaicin injection, produced an acute impairment in locomotor function and increased hemorrhage. Finally, we assessed the effect of capsaicin and shock treatment on long‐term recovery. Female rats, treated as described above, were monitored for behavioral recovery over 28 days. Again, both shock and capsaicin produced a deficit in locomotor function, impairing behavioral recovery.
Supported by grants from the NIH (NS104422 and NS091723), DOD (SCI70241) and the Craig H. Neilsen Foundation to JWG
Keywords: Sex, Capsaicin, Recovery
PAIN INPUT INCREASES HEMORRHAGE AT THE LESION SITE AFTER TRAUMATIC BRAIN INJURY
Texas A&M University, Psychological and Brain Sciences, College Station, USA
Traumatic brain injury (TBI) is a major cause of death and disability in the United States. Many of these injuries are the result of events such as car accidents, combat violence, and falls, and often result in additional injuries (polytrauma) that serve as a source of pain. Previous work in our laboratory has shown that pain is detrimental to recovery after spinal cord injury (SCI) and leads to increased lesion site hemorrhage. It is not known whether these findings generalize to other neurologic insults. The present study sought to determine whether pain input expands the area of hemorrhage after TBI. Male Sprague‐Dawley rats (N = 12) weighing between 275‐300 grams were given a moderate traumatic brain injury in the right parietal region centered over the primary motor cortex, using the Leica One controlled cortical impact device (2mm impactor tip, 4 m/s, deformation depth 3mm). A day later, the irritant capsaicin (3%, 50 ml) or vehicle was applied to the contralateral hindpaw via a subdermal injection. Behavioral tests were performed at zero and three hours post pain input. After three hours, animals were euthanized and perfused with 4% paraformaldehyde. Sections were stained with hematoxylin and eosin to quantify hemorrhage extent at the lesion site, and sections were imaged. We found that pain input increased the area of hemorrhage at the injury site (p < .05) and produced an acute disruption in behavior. Additional analyses are being performed to determine the extent of capillary fragmentation in the region of injury.
Supported by grants from Mary Tucker Currie Endowment to JWG.
Keywords: polytrauma, C‐fiber, capsaicin, motor cortex
IS THERE A PHENOTYPE OF PERSISTENT PAIN IN PERSONS WITH MILD TRAUMATIC BRAIN INJURY?
Jaclyn Portanova1, Diana Buchanan1, Megan Moore2,3,
1The University of Washington, School of Nursing, Seattle, USA
2The University of Washington, School of Social Work, Seattle, USA
3Harborview Injury Prevention and Research Center, Seattle, USA
Acknowledgements: Supported, in part, by NIH/NINDS R01NS077913 (HT), NIH/NINR 5T32NR014833 (JP) and the Hester McLaws Fellowship (JP).
Keywords: persistent pain, risk factors, symptom clusters
HEADACHE TRAJECTORY AND CUMULATIVE MORBIDITY AFTER TRAUMATIC BRAIN INJURY
1University of Pittsburgh, PM&R, Pittsburgh, USA
2Mount Sinai, Icahn School of Medicine, New York, USA
3Safar Center for Resuscitation Research, University of Pittsburgh, Pittsburgh, USA
4Clinical and Translational Science Institute, University of Pittsburgh, Pittsburgh, USA
Headaches are a common secondary condition after a traumatic brain injury (TBI) that can persist chronically. However clinically, post traumatic headache rarely manifests as an isolated event, often co‐occurring with other common TBI impairments such as post‐traumatic depression. Moderate‐to‐severe TBI in particular is associated with mood and cognitive impairments that impact quality‐of‐life (QOL) and return‐to‐work after injury. The burden of headaches in addition to the post‐traumatic cumulative morbidity burden has not previously been characterized. Also, pain characteristics (e.g. pain type, location, or severity) and headache‐associated symptoms (e.g. vision changes), have not yet been assessed longitudinally in a TBI population. Likewise, the onset and subsequent trajectory of headaches after TBI have not yet been assessed. The aim of our study was to identify headache phenotypes and how these phenotypes are associated with other TBI outcomes. We used monthly questionnaires to categorize headaches to generate temporal headache trajectories in a prospective cohort of adults with TBI (n = 79). Headache frequency, severity, number of headache days, and pain type were used to describe the trajectory groups. We examined relationships between trajectories and other common TBI outcomes, including QOL and other common TBI comorbidities, including anxiety, depression, and fatigue. We observed three distinct headache profiles: low (n = 21), resolve (n = 23), and chronic (n = 35). The chronic group reported more frequent headaches, more headache days per month, and more severe headaches compared to those in the resolve headache group (p < 0.1 all comparisons). We observed differences in headache location and pain type between the chronic and resolve groups. Individuals in the chronic group experienced lower QOL, and had higher anxiety, depression, and fatigue scores (p < 0.05 at various timepoints). Future studies should identify how personal biology contributes headaches and TBI outcome.
Support: NIDILRR‐90DP0041.
Keywords: headache, cumulative morbitidy, TBI
IDENTIFYING PLASMA DERIVED EXTRACELLULAR VESICLE (EV) CONTAINED BIOMARKERS OF CHRONIC PAIN USING A SPINAL NERVE LIGATION MODEL
1US Army Institute of Surgical Research, Burn and Soft Tissue Research, JBSA Fort Sam Houston, USA
2Frederick National Lab for Cancer Research, Advanced Biomedical Computing Center, Fort Detrick, USA
3US Army Center for Environmental Health Research, Fort Detrick, USA
Discovery of novel biomarkers of neuropathic pain can aid in uncovering novel pathways and treatments for preventing the development and maintenance of neuropathic pain after traumatic injury. Currently, research into potentially novel biomarkers for chronic neuropathic pain are lacking. This study examined the plasma derived Extracellular vesicle (EV) miRNA content in a chronic neuropathic pain rat model. This was accomplished by performing either spinal nerve ligation (SNL; n = 6) or sham (n = 6) surgery on anesthetized male Sprague‐Dawley rats. Mechanosensitivity was assessed and plasma derived EV RNA was isolated at baseline, and days 3 and 15 post‐nerve injury. EV extracted small RNA was sequenced followed by differentially expressed (DE) miRNAs and gene target enrichment/signaling pathway analysis performed using R packages and TargetScan/Ingenuity pathway analysis, respectively. Seven of the DE miRNAs were validated by Reverse Transcription‐quantitative Polymerase Chain Reaction (RT‐qPCR). Results showed a reduction in withdrawal latency from day 3 to 15 post‐nerve injury in SNL rats. The key miRNA findings include 1) the majority of the DE EV miRNAs, which normally function to suppress inflammation, were downregulated, and 2) several of the plasma derived DE EV miRNAs reflect previously observed changes in the injured L5 nerve. These plasma derived DE EV miRNAs regulate processes important in the development and maintenance of neuropathic pain states and potentially serve as key regulators, biomarkers, and targets in the progression and treatment of chronic neuropathic pain.
Keywords: miRNA, Exosome, Neuropathic pain, Blood, Plasma
IMPAIRED MOTOR CORTICAL EXCITABILITY IN VETERANS WITH GULF WAR ILLNESS RELATED HEADACHE AND BODY PAIN
Albert Leung1,2,3,
1VA San Diego, San Diego, USA
2UCSD, La Jolla, USA
3VMRF, San Diego, USA
Headaches and body pain are debilitating conditions of Gulf War Illness (GWI), a chronic multisymptomatic illness that affects 1990‐91 Persian Gulf War veterans. There is little known about pathophysiology of GWI. Impaired motor cortical excitability is known to be associated with deficit in supraspinal pain modulatory functions due to trauma or other causes. To further understand the pathophysiology, the resting motor threshold (RMT) determined as the minimum % of the maximum intensity from transcranial magnetic stimulation (TMS) needed to elicit motor response, which is dependent on neuronal excitability, was compared in patients with GWI and chronic headaches, muscle and joint pain with gender and age matched healthy veterans, hypothesizing cortical excitability of the motor cortex is suppressed in patients. MRI anatomical scans (176 slices, T1, 256x256, and 1cm slice thickness) were processed with BrainVoyager Neuronavigation to guide the TMS coil. Electromyography recordings were taken from electrodes attached to the flexor pollicis brevis muscle and a ground electrode on the back of the hand. A figure of eight coil connected to MagProR30 delivered a single pulse TMS at the left motor cortex to determine the RMT based on an established protocol (Khedr EM et al 2005). The GWI group (N = 19) demonstrated a significantly (P < 0.0001) higher RMT than the healthy control group (N = 19). The average RMT (%±) for the GWI group was 77% ± 17% compared to 55% ± 8% for the healthy population. Patients with GWI and chronic pain showed impaired motor cortical excitability which in turn reduced their intrinsic supraspinal pain modulatory functions. While additional studies are required to further understand the pathophysiology of GWI and chronic pain associated with this finding, actively stimulating the motor cortex with TMS may provide an effective means to rectify this underlying supraspinal pain modulatory deficit.
Keywords: Gulf War Illness, Headache, Motor Cortical Excitability, Transcranial Magnetic Stimulation
A15 Rehabilitation
ROLE OF NOCICEPTIVE AFFERENT INPUT ON FORELIMB MOTOR RECOVERY WITH STRENGTH TRAINING IN THE SPINAL CORD INJURED RAT
Drexel University, Neurobiology and Anatomy, Philadelphia, USA
Individuals with spinal cord injury (SCI) suffer a loss of motor and sensory function. The current standard of care to recover fine motor control and reduce pain is rehabilitation focused on a combination of range of motion, aerobic and strength training (ST). However, limited research has been done to determine the role of nociceptive afferent inputs from muscle on spinal plasticity and/or recovery of function. To explore this, Sprague‐Dawley rats received a unilateral C5 SCI and were assigned to either no ST, early ST starting 5 days post‐SCI, or delayed ST at 42 days post‐SCI. The rats were trained to reach through a narrow slot in a test cage to repetitively pull a handle with at least 50g of force to receive a food reward. Several measures of forelimb strength were recorded over time. A single pellet retrieval task was performed to observe the effect of strength training on fine motor control. SCI rats received injections of cholera toxin‐b (CTB) into median and ulnar nerve and were perfused 3 days later. To determine the anatomical plasticity of primary afferent fibers following SCI and ST, cervical spinal cords were stained for antibodies against CTB, CGRP, and isolectin‐B4 to identify large diameter, myelinated afferents, peptidergic nociceptive afferents, and isolectin‐B4 of non‐peptidergic nociceptive afferents, respectively. Multivariate statistical analyses of the behavioral and anatomical outcomes of the ST are underway. An understanding of the role of nociceptors in spinal plasticity and functional motor and sensory recovery of SCI patients will guide future research and refine rehabilitation strategies to further improve their quality of life.
Support contributed by the Craig H. Neilsen Foundation #457508.
Keywords: primary afferent plasticity, Upper extremity function, behavior
UNDERSTANDING GUARDIANSHIP AFTER TRAUMATIC BRAIN INJURY
The University of Washington, Seattle, USA
Keywords: Guardianship, Legal Capacity, Outcomes, Disability
ASSESSING SLEEP AFTER TRAUMATIC SPINAL CORD INJURY
University of Pittsburgh, School of Nursing, Pittsburgh, USA
Sleep has a critical role in the maintenance of neuroplasticity and removal of neurotoxins that can lead to neurodegeneration and cognitive impairment. Traumatic spinal cord injury (TSCI), yields a robust inflammatory and systematic immune response, that contributes to impaired homeostatic regulation, increased fatigue and sleepiness, along with depressive symptoms. Sleep impairment after TSCI is highly prevalent, however, assessment beyond subjective report is not routine of care. The purpose of this study was to examine real time physiological markers of sleep, to characterize sleep architecture, sleep latency and positioning using frontal EEG objective measure in the subacute rehab phase of recovery. This prospective, exploratory pilot, examined objective EEG data, using the Sleep Profiler™ (Advanced Brain Monitoring, Carlsbad, CA, USA) and symptom data collected from an ongoing study conducted between September 2018 and February 2019. Participants were recruited through the University of Pittsburgh Model System on Spinal Cord Injury. The sample (N = 7) demographics are white (85.7%), male (71%), with average age of 44 years (±22.2; range = 18‐71). The spinal level is primarily cervical (42.2%) and thoracic (42.2%), while the American Spinal Injury Association Impairment score (AIS) is primarily D (71.4%). For over half of participants (86%), total sleep per night for two nights was 5 hours or less, with none of the participants achieving at least 20% REM sleep, which is essential for health maintenance. Half of participants reported difficulty with concentration (50%); feeling tired (50%); and reported difficulty with falling or staying asleep (90%). All participants reported feeling down, depressed, or hopeless. The clinical assessment of sleep after TSCI is critical given the sequela of secondary injury as a result of inflammation and its impact on long‐term recovery and functional outcomes. Early objective sleep assessment can lead to more evidence based intervention and potentially improve symptom management and functional outcomes. Support: Robert Wood Johnson Foundation; National Institute of Health (T32NR009759)
Keywords: traumatic spinal cord injury, impaired sleep, EEG, neuroprotection
THE EFFECT OF EXPERIMENTAL BRAIN TRAUMA ON SUSTAINED ATTENTION IN FEMALE RATS
University of Pittsburgh, Physical Medicine and Rehabilitation, Pittsburgh, USA
Long‐term sequelae after traumatic brain injury (TBI) include attention and concentration impairments. We reported attentional deficits after moderate TBI, using the operant 3‐choice serial reaction time task (3‐CSRT) and the digging attentional set‐shifting (dAST) test in male rats. Given that over 40% of TBIs occur in women, it is pivotal to assess complex cognition in injured female rats. We hypothesized that adult females will exhibit reduced accuracy and increased impulsivity post‐TBI. The 3‐CSRT requires subjects to divide attention between three nose‐poke holes in an operant chamber, with brief (300 ms) cues being presented randomly. Upon reaching 70% accuracy using incrementally shorter cues, adult female normal‐cycling Sprague‐Dawley rats were subjected to a controlled cortical impact (2.8 mm deformation depth, 4 m/sec) or sham injury over the right parietal cortex. After two weeks of recovery, they were re‐tested on 3‐CSRT for ten days and then trained/tested on dAST, which involves a series of complex stages, including simple and compound discriminations, reversals, and intra/extradimensional set‐shifts, at day 28 post‐surgery. Dependent measures include percent accuracy and omissions, and premature responses (3‐CSRT), as well as trials to reach criterion, total and perseverative errors (dAST). Results suggest that TBI females display reduced percent accuracy, as well as increased omissions and premature responses (i.e., reduced vigilance) when re‐tested on 3‐CSRT compared to Sham rats (n = 3/group), paralleling similar findings in males. Ongoing analyses include post‐surgery reaction times, dAST performance (total trials and errors), as well as within‐subject correlations between test modalities. Statistical analyses will employ repeated‐measures ANOVA followed by Newman‐Keuls post hoc for individual days when appropriate. In summary, preliminary results show that sustained attention may be similarly impacted by brain trauma in female versus male adult rats. Assessing attention post‐TBI via multimodal testing is clinically‐relevant and may provide reliable avenues towards developing therapeutic and rehabilitation targets in both males and females.
Grants: NIH NS094950, NS099683; Pitt Rehab. Inst.
Keywords: Attention, Female, Cognitive Flexibility, AST, Operant Behavior
GOAL‐DIRECTED BEHAVIOR AND MOTIVATION IN ADOLESCENT RATS SUBJECTED TO PEDIATRIC BRAIN TRAUMA
University of Pittsburgh, Physical Medicine and Rehabilitation, Pittsburgh, USA
Childhood‐acquired brain trauma accounts for 500,000 yearly emergency room visits. Therefore, the effect of brain trauma on executive function maturation, such as learning, motivation, and behavioral flexibility, is of major importance. We hypothesized that rats subjected to pediatric traumatic brain injury (TBI) will display impairments in instrumental learning task (ILT) behavior and behavioral flexibility during adolescence. Sprague‐Dawley rats (postnatal day, PND 17) received moderate controlled cortical impact (2.2 mm deformation depth, 4 m/sec) or sham injury to the right parietal hemisphere. Ten days later, they were trained for 12 consecutive days on a fixed‐ratio schedule of 1 in operant chambers with three nose‐poke holes and a food trough delivering sucrose pellets. They poked in the center hole when illuminated, for 99 trials or 30 min, whichever occurred first. Outcomes included number of completed trials, task‐irrelevant pokes (left or right), and latencies for nose‐poking and pellet retrieval. Rats were then trained/tested on the attentional set‐shifting test (AST) at PND 42‐43, which involves simple and compound discriminations, reversals, and intra/extradimensional set‐shifts. Dependent measures included number of trials to criterion, as well as total and perseverative errors. Repeated‐measures ANOVAs were performed, followed by Newman‐Keuls post hoc for individual days. ILT data (n = 8/group) paradoxically demonstrate TBI increased total trials and reduced task‐irrelevant pokes, suggesting attenuated exploratory drive but also reduced impulsivity (p < 0.05). These effects were not due to pellet retrieval alterations, as poke‐to‐pellet latencies were shorter in TBI rats (p < 0.05). No group differences were detected in AST, possibly due to higher baselines in Sham adolescents, as previously reported in the literature. In summary, adolescent instrumental learning is affected by pediatric TBI in a divergent manner, reflecting reduced exploratory drive without affecting motivation. Executive function was not impaired, albeit adolescent rats display cognitive rigidity compared to adults. These findings will advance our understanding of long‐term higher‐order cognitive and motivational deficits in adolescent survivors of childhood brain trauma. Grants: NIH NS094950, NS099683; Pitt Rehab. Inst.
Keywords: Attention, Operant Behavior, Adolescent, Motivation
MORE THAN JUST 'DISPO': EFFECTS OF AN ACUTE CARE BRAIN INJURY MEDICINE CONTINUITY SERVICE ON HEALTHCARE UTILIZATION AND REHAB
1University of Pittsburgh Medical Center, PM&R, Pittsburgh, USA
2Wenatchee Valley Hospital & Clinics, PM&R, Wenatchee, USA
Previous work demonstrates that early acute care physiatric consultation improves acute healthcare utilization and acute care outcomes after hospitalization with TBI. We studied patient outcomes among severe brain injury survivors followed in the acute setting by a Brain Injury Medicine (BIM) continuity consultation service. 238 patients were admitted to a single‐center brain injury rehabilitation unit for their initial inpatient rehabilitation (IPR) stay over a two‐year period. Of these, 73 were followed by the BIM continuity service during acute care; the remainder were controls. Treated at the same acute care and IPR facilities, those followed by the BIM consultation service received additional acute management including screening for medical complications, management of sleep/wake cycles, neurostimulation, paroxysmal sympathetic hyperactivity, agitation, electrophysiology, bracing, spasticity, pain, transitions of care, and family education/prognosis. No significant demographic or clinical differences were noted between groups. BIM consult cases were substantially more complex, having a greater number of comorbidities (p = 0.044), and a higher Case Mix Index than controls (p < 0.001). Despite this, BIM cases spent 6 fewer days in acute care. BIM rehabilitation lengths of stay (LOS) were 5.2 days longer than controls. Among disorders of consciousness (DoC) patients, JFK Coma Recovery Scale score gains were similar at IPR, however more BIM patients than controls emerged from a minimally conscious state during IPR as their initial JFK scores were higher upon IPR admission (p = .006). 31 non‐BIM patients were discharged to acute care unexpectedly and did not return to IPR (readmission penalty $180,432), compared to only 3 BIM patients transferred off unexpectedly without returning (readmission penalty $17,679). Early physiatric interventions by the BIM continuity service had a significant impact on quality of care, effectively facilitating patient transitions for early admission to rehabilitation, decreasing unplanned transfers, and increasing the likelihood of emerging from a minimally conscious state at our institution.
Keywords: Traumatic Brain Injury, Anoxic Brain Injury, Neurotrauma, Neurorehabilitation
A16 Stem Cells
EXOSOME TREATMENT IMPROVES FUNCTIONAL RECOVERY AFTER TRAUMATIC BRAIN INJURY IN RATS: A DOSE‐RESPONSE AND THERAPEUTIC WINDOW STUDY
1Henry Ford Hospital, Neurosurgery Research, Detroit, USA
2Henry Ford Hospital, Neurology, Detroit, USA
3Oakland University, Physics, Rochester, USA
4Henry Ford Hospital, Biostatistics and Research Epidemiology, Detroit, USA
We have previously demonstrated that treatment of traumatic brain injury (TBI) 24h post injury, with exosomes harvested from bone marrow mesenchymal stem cells, significantly improved functional recovery. The present study was designed to determine the dose‐response and therapeutic window of exosomes for treatment of TBI (n = 8 rats/group). In Experiment 1: male rats subjected to moderate TBI induced by controlled cortical impact randomly received phosphate‐buffered solution (PBS) or one dose of exosomes (50, 100, 200 μg/rat) 24h after injury. In Experiment 2: TBI rats randomly received PBS or 100 μg exosomes starting at 1, 4, and 7 days after injury. Neurological functional tests were performed 1 day and weekly after TBI for 5 weeks. Spatial learning was measured on days 31‐35 after TBI using the Morris water maze test. Analysis of variance (ANOVA) followed by post hoc Tukey's tests was used for data analyses. In Experiment 1, all the doses of exosomes significantly improved sensorimotor and cognitive function (p < 0.05). However, the exosome treatment at 100 μg/rat resulted in a more rapid and significantly greater reduction of these deficits compared with rats treated with the 50 μg or 200 μg exosomes (p < 0.05). In Experiment 2, treatment with exosomes at 100 μg/rat starting 1, 4, and 7 days post TBI significantly reduced neurological deficits and improved cognitive function (p < 0.05). However, the exosome treatment starting at 1 day post TBI resulted in a significantly greater reduction of these deficits compared with TBI rats treated with exosomes at the two later time points (p < 0.05). In summary, exosome therapy for male rats with therapy initiated 24h post TBI at 100 μg/rat provides a superior therapeutic window of treatment compared with treatment initiated at 4d or 7d time points. Exosome treatment at 100 μg/rat provides a robust therapeutic effect for treatment initiated at 24h post TBI in male rats, indicating that cell‐free exosomes may have potential as a novel treatment of TBI.
Keywords: stem cell therapy, exosome, functional outcome, rat, traumatic brain injury
3D ANALYSIS OF HUMAN NEURAL STEM CELL MIGRATION IN NAïVE MOUSE BRAIN AND TOWARDS TRAUMATIC BRAIN INJURY USING CLARITY
Margarita Gutova4, Russell Rockne4, Nicole Saltiel1, Andrew Pearson1,2, Vikram Adhikarla4, Lusine Tsaturyan4, Scott Ferguson1,2,3, Ghania Ait‐Ghezala1,2,3, Fiona Crawford1,2,3,
1Roskamp Institute, Sarasota, USA
2The Open University, Milton Keynes, United Kingdom
3James A. Haley Veteran's Administration, Tampa, USA
4Beckman Research Institute of City of Hope, Duarte, USA
Keywords: mild TBI, Neuroninflammation, Stem cells, CLARITY
NEURAL STEM CELL TRANSPLANTATION MITIGATES PENETRATING BALLISTIC‐LIKE BRAIN INJURY (PBBI) INDUCED MOTOR DEFICIT
1Univ of Miami, Miami, USA
2WRAIR, Brain Trauma Neuroprotection and Neurorestoration Center, Silver Spring, USA
Penetrating traumatic brain injury (PTBI) is associated with poor neurological outcomes. No restorative treatments are currently available. Cell replacement via neural stem cell transplantation is a putative therapeutic approach based on preclinical studies. Previous studies from our group established (i) durable engraftment of human fetal NSC (hNSC; Neuralstem Inc.), FDA approved for use in clinical trials, (ii) optimal location and injury‐transplant interval. This study tests the hypothesis that engraftment and PTBI deficit amelioration will be cell dose dependent.
Fifty adult male Sprague Dawley rats were randomized to five groups (10 per group). Unilateral PTBI was induced by rapid inflation of a balloon on a perforated probe stereotactically inserted through the right frontal lobe in 30 rats. Pair of injured and uninjured (Sham) to receive either 160,000 cells/rat (0.16M)‐ low dose or 1,600,000 cells/rat (1.6M) ‐ high dose of hNSCs intracerebrally in PTBI perilesion. The injured group with vehicle injection served as negative control. Animals were immunosuppressed and assessed on ‘GridWalk’ for motor ability pre transplantation and 12 weeks post transplantation. The mean left front foot faults pre transplant were 23.2 ± 3.34 (n = 30). At 12 weeks post transplantation, vehicle, low and high cell dose group LFF were 25.6 ± 2.386 (n = 10), 13 ± 0.948 (n = 5) and 21.2 ± 3.917 (n = 5) respectively. One‐way ANOVA revealed statistical significant differences only between pre transplant and 12 week low dose group (PTBI +0.16M 12wk) with a mean difference of 10.2 and p value 0.0016. GFP cell count based engraftment was not significantly different for a given cell doses between groups.
Thus a cell dose dependent therapeutic effect in conjunction with previous data collectively support the notion that hNSC transplants preserve motor function. Follow up studies in gyrencephalic TBI models with appropriate cell dose would help arrive at appropriate cell dose for a human application.
Funded by DOD W81XWH‐16‐2‐0008, BA150111 CDMRP JPC‐6.
Keywords: Penetrating traumatic brain injury, Penetrating ballistic‐like injury, frontal lobe, motor function
LONG‐TERM PRECLINICAL SAFETY EVALUATION OF CLINICAL‐GRADE HUMAN NEURAL STEM CELLS IN RODENT MODEL OF TRAUMATIC BRAIN INJURY
1University of Miami, Miami Project to Cure Paralysis, Miami, USA
2Walter Reed Army Institute of Research, Brain Trauma Neuroprotection, Silver Spring, USA
Traumatic brain injury (TBI) is a progressive disease, characterized with disability amongst its survivors due to loss of neural tissue. Transplantation of neural stem cells (NSCs) is an option to replace lost cells and restore function. Following robust durable engraftment of clinical trial grade human fetal neural stem cells (hNSC; Neuralstem Inc.), we initiated a safety/tumorigenicity study needed in order to obtain FDA approval for a TBI clinical indication. To evaluate the potential tumorigenicity of hNSCs, cells were transplanted in immune‐compromised rats with penetrating ballistic‐like brain injury (PBBI). Adult male athymic rats were subjected to unilateral PTBI via rapid inflation of a balloon attached to a perforated probe that was stereotactically inserted through the right frontal cortex. Animals were randomized to two groups (n = 20 per group). At one‐week post‐injury, animals received perilesional microinjection of vehicle (Group A) or 3 million green fluorescent protein (GFP) expressing hNSCs (Group B). Animals were euthanized at 6 months post‐transplantation. Tumorigenecity potential was assessed by examining brain and peripheral organ sections for oncogenic features such as abnormal mitoses, nuclear atypia, and necrosis in hematoxylin eosin stained section as well as quantitation of Ki67 positive mitotic figures in brains and spinal cords. The transplanted cells within brain sections showed pleomorphic density with seamless boundaries and no signs of tumorigenicity. Neither morphological nor immunohistochemical indicators indicative of preneoplastic or neoplastic growth were evident in transplanted cells. No abnormal masses were detected in peripheral tissues. While some peripheral tissue masses were detected, these were found to be benign neoplasms common to this species of rodents.
Collectively, data supports the notion that hNSC can be considered a safe cell therapy option for TBI patients. Support:W81XWH‐16‐2‐0008, BA150111 CDMRP JPC‐6
Keywords: human neural stem cells, tumorigenicity, TBI, Penetrating, Neuroprotection
POTENTIAL OF AN ARTIFICIAL SPINAL CORD IN THE TREATMENT OF SPINAL CORD INJURY
Wayne State University School of Medicine, Detroit, USA
Several studies have investigated material‐based and cellular constructs for spinal cord injury (SCI). However, no one has tried to replicate the cytoarchitecture of the spinal cord and address issues specific to SCI. The Artificial Spinal Cord (ASC) consists of a central layer of olfactory neural progenitor cells on hyaluronic acid electron spun fibers surrounded by two layers of electrospun fibers with opposing gradients of microspheres that slowly release neurotrophic factors (GDNF or BDNF) that is in a hydrogel containing olfactory ensheathing cells to myelinate and chondroitinase ABC to prevent scar formation. We implanted this construct into a rat model of severe spinal cord injury in which a 4‐5 mm segment of spinal cord was removed. Eighteen inbred male Lewis rats were randomly assigned into 4 groups: Sham (T7‐T11 laminectomy only); Segment removal with No graft; Segment removal with Hydrogel only; and Segment removal with ASC. A sterile surgical steel wire (25 gauge) bent in a hairpin shape around the spinous processes was used to stabilize the vertebral column. All animals were exposed to an enriched environment with exercise and underwent blinded weekly functional testing (BBB locomotor test, inclined plane, beam, Hargreaves and ladder rung test) for 15 weeks. Data were analyzed using ANOVA (significance p < 0.05). Rats receiving the ASC after spinal segment removal significantly improved in each of the functional tests. ASC group was the only group to gain hind limb weight support and front limb–hind limb coordination. In response to mildly painful stimulation using the Hargreaves apparatus, rats with ASC reacted similarly to the sham operated rats. The rats receiving the ASC went from a severe to a mild SCI. The artificial spinal cord is a platform for further improvement and holds great promise in the treatment of severe spinal cord injury. Support from Lone Star Foundation.
Keywords: Neurotrophic factors, electrospun fibers, hydrogel, microspheres, spinal cord injury, olfactory stem cells
A17 Therapeutics / Drug Discovery
HDACI‐LOADED NANOPARTICLES TO TREAT TRAUMATIC BRAIN INJURY
1Arizona State University, Biomedical Engineering, Tempe, USA
2Arizona State University, School of Life Sciences, Tempe, USA
3University of Texas Medical School, Vivian L. Smith Department of Neurosurgery, Houston, USA
Traumatic brain injury (TBI) is a major cause of disability, with approximately 1.7 million incidents reported annually. Following a TBI, patients are likely to sustain sensorimotor and cognitive impairments and are at an increased risk of developing neurodegenerative diseases later in life. Despite TBI's prevalence and enduring effects, robust therapies that treat TBI neuropathology are not available in the clinic. One emerging therapeutic approach is to target epigenetic mediators that modulate a variety of molecular regulatory events acutely following injury. Specifically, previous studies demonstrated that histone deacetylase inhibitor (HDACi) administration following TBI reduced inflammation, enhanced functional outcomes, and was neuroprotective. Here, we evaluated a novel quisinostat‐loaded PLA‐PEG nanoparticle (QNP) therapy in treating TBI as modeled by a controlled cortical impact in adult C57BL/6 mice (CCI; 2 mm tip diameter, 6.0 m/s over the frontoparietal cortex); all experiments were approved by ASU IACUC. Briefly, we evaluated initial pharmacodynamics within the injured cortex via histone acetylation levels following administration of QNPs. A second cohort of mice underwent a battery of behavioral assessment over the course of a month following CCI and QNP intervention (rotarod, open field, gridwalk, and Morris water maze). We observed that QNP administration acutely following injury increased histone acetylation specifically within the injury penumbra, as detected by Western blot analysis. Initial behavioral results indicate that QNP treatment dampened motor deficits as measured by increased rotarod latency to fall relative to blank nanoparticle‐ and saline‐treated controls. Additionally, open field results show that QNP treatment altered locomotion following injury. These results suggest that HDACi therapies are a beneficial therapeutic strategy following neural injury and demonstrate the utility for nanoparticle formulations as a mode for HDACi delivery following TBI. Funding: NINDS R21‐NS107985.
Keywords: TBI, Nanoparticle, histone deacetylase, quisinostat
STATUS OF N‐ACETYL CYSTEINE?
Defense and Veterans Brain Injury Center, Clinical Affairs, Silver Spring, USA
A 2013 clinical trial of N‐Acetyl Cysteine (NAC) in deployed service members with blast mTBI found that those treated with NAC were significantly more likely to recover from dizziness, headache and other post‐concussive symptoms by seven days after injury compared with a placebo‐treated group. Despite these promising results, there has been a paucity of clinical trials evaluating NAC.
The 2014 DoD Neurotrauma Pharmacology Workgroup Report concluded NAC has antioxidant and neuromodulatory activity with minimal adverse effects but requires potency and therapeutic window analysis to determine efficacy. The report recommended replication of the blast study findings in a larger population. Multiple reviews have also noted minimal safety concerns, improved neurofunctional outcomes, decreased oxidative stress and inflammation at cellular and molecular levels; and the need for adequately powered clinical trials with more extensive TBI and other mechanisms of injury.
The amide derivative of NAC, N‐acetyl cysteine amide, (NACA), has demonstrated increased BBB permeability relative to NAC. Additionally, pre‐clinical studies demonstrated increased brain concentrations of NAC when NAC was combined with the adjuvant, probenecid. In a study of children with severe TBI, the combination of probenecid and NAC (pro‐NAC) resulted in a progressive increase in the CSF concentration of NAC relative to serum concentration. Metabolomic assessment of the same CSF showed enhanced glutathione related pathways in the pro‐NAC treated group, suggesting target engagement.
The Operation Brain Trauma Therapy (OBTT) consortium was unable to execute desired analysis of an NAC analog but NAC and pro‐NAC will be considered for future analysis pending funding of OBTT‐II.
Optimization of dosing regimens, safety assessment of NACA and determination of long‐term therapy effects are needed. However, the favorable benefits versus risks of NAC warrant timely replication of the blast study findings. Replication should occur in adequately powered clinical trials with and without probenecid in acute TBI with longitudinal administration and follow‐up. Concurrently, expanded, multi‐level efficacy and outcomes assessments, including target engagement correlating genomic expression alterations with biomarkers and symptom presentation/resolution are needed to enable progression of NAC for use in service members affected by TBI.
Keywords: TBI, N‐acetyl cysteine
NEUROPROTECTION OF POLYNITROXYLATED PEGYLATED HEMOGLOBIN IN GUINEA PIGS WITH TRAUMATIC BRAIN INJURY COMBINED WITH HEMORRHAGE SHOCK
1Johns Hopkins University, Baltimore, USA
2AntiRadical Therapeutics, Sioux Falls, USA
Keywords: polynitroxylated PEGylated hemoglobin, traumatic brain injury, arterial blood pressure, guinea pigs, neuron
TRANEXAMIC ACID PHARMACOKINETICS IN PATIENTS WITH MODERATE OR SEVERE TRAUMATIC BRAIN INJURY
1Oregon Health & Science University, Division of Trauma, Critical Care & Acute Care Surgery, Portland, USA
2University of Washington, Department of Biostatistics, Seattle, USA
3Portland State University, Department of Pharmacology, Portland, USA
4Orlando Health Regional Medical Center, Department of Emergency Medicine, Orlando, USA
Keywords: TBI, Tranexamic Acid, Pharmacokinetics
DELAYED DOSING OF MINOCYCLINE PLUS N‐ACETYLCYSTEINE LIMITS GRAY MATTER INJURY AND RESTORES FUNCTION AFTER EXPERIMENTAL TBI
SUNY‐Downstate, Physiology and Pharmacology, Brooklyn, USA
There are currently no approved drug treatments for traumatic brain injury (TBI). After TBI, treatment may be delayed due to lack of medical access or perceived symptom resolution. Therefore, a clinically useful drug to treat TBI must retain potency with delayed dosing. The potency of the drug combination minocycline plus N‐acetylcysteine was examined when first dosed 72 hours (MN72) post‐injury (PI) in a unilateral closed head injury (CHI) mouse model. CHI produces long‐term and likely permanent impairments on Barnes maze, a spatial navigation task that requires one intact hippocampus. CHI decreases synaptic density and impairs long term potentiation (LTP) in the hippocampus ipsilateral and contralateral to the impact site. MN72 improves acquisition of Barnes maze, increases synaptic density and restores LTP in the contralateral hippocampus. In contrast, a first dose of drugs at 12 hours (MN12) PI bilaterally restores behavior, synaptic density and LTP. At 14 days PI, hippocampal regions CA3 and CA1 have bilateral neuronal loss. Golgi stain analysis of the surviving neurons reveals fewer dendrites with shorter branches and reduced complexity and synaptic fields. In CA1, MN72 bilaterally prevents neuronal loss and prevents dendritic degeneration. MN72 does not prevent CA3 neuronal loss, but protects spared neurons from further degeneration. MN72 also restores CHI‐induced loss of the dendritic proteins MAP2 and PKMζ. Expression of both proteins decreases bilaterally within 3 days PI and does not recover in the ipsilateral hippocampus. In the contralateral hippocampus, MN72 accelerates recovery of MAP2 expression, yet in all groups MAP2 expression recovers by 60 days PI. PKMζ expression, in contrast, recovers only after MN72 treatment. These data suggest that (1) CHI produces a diffuse gray matter injury, and (2) MN72 is less potent than MN12, yet MN72 retains potency since there are multiple cellular and synaptic functions that can still be targeted 3 days PI. Minocycline plus N‐acetylcysteine limits gray matter injury and improves function when dosed at a clinically relevant therapeutic window, and is an excellent candidate to treat clinical TBI.
Keywords: Preclinical, Dendrites, Morphology, Closed head injury, Protein expression
CYTOPROTECTIVE ADORA3 AGONIST AST‐004 REDUCES CELL DEATH RATES OF TRAUMATIZED HUMAN ASTROCYTES
1UCLA, Semel Institute for Neuroscience and Human Behavior, Los Angeles, USA
2UTH, Department of Cell Systems and Anatomy, San Antonio, USA
3Astrocyte Pharmaceuticals Inc., Cambridge, USA
Traumatic brain injury (TBI) causes cell injury and cell death inflicted by mechanical shear and deformation of injured brain tissue. No effective therapies for TBI patients mitigate long‐lasting neurological deficits. One recovery strategy is to interfere with ensuing cell death after trauma by targeting energy homeostasis. Our objective investigates this strategy using a new G‐protein coupled metabotropic adenosine receptor (ADORA3) agonist AST‐004, in a human trauma culture model. In vitro matured human astrocytes were traumatized using abrupt pressure‐pulses that produce shearing and inflict acute mechanoporation and progressing cell death. (Wanner, IB 2012; Halford J et al., 2017). Acutely traumatized astrocytes were treated 1x or 6x over 48 hours using a range of AST‐004 doses. Integrity‐compromised cells were identified by live‐propidium iodine uptake, followed by glial fibrillary acidic protein (GFAP) and nuclear staining. Automated stage‐microscopy provided unbiased tiled images. Cells were objectively counted using quality‐controlled, binarized images. PI‐positive cell numbers increased significantly by 3‐fold post‐stretching. At all doses tested, AST‐004 reduced trauma‐inflicted cell death by 4‐fold. This significant decrease was further investigated by determining different cell death stages. One‐fifth of permeable cells displayed complete chromatin condensation or nuclear fragmentation, while the majority displayed earlier stages of cellular demise. Stretching caused significant, 4‐fold, increase in disassembled GFAP‐bearing astrocytes that had 98‐100% pyknotic nuclei. This population was significantly, 3‐fold, reduced by AST‐004. The data suggest that the drug successfully ameliorated compromised human astrocytes from progressing to cell death. Disassembled GFAP fibers are related to elevated intracellular calcium and calpain activation. Thus, the drug may restore ion homeostasis, energy levels and cellular integrity. In conclusion, AST‐004 is cytoprotective by shifting cell fates of traumatized human astrocytes towards prolonged survival. Future studies will further elucidate drug action and kinetics to guide therapeutic dosing for clinical use in TBI patients.
Keywords: cell death, human, metabotrophic adenosine receptor, GFAP, mechanoporation, survival
COMBINATION OF THE LIPID PEROXIDATION INHIBITOR U‐74389G AND CARBONYL SCAVENGER PHENELZINE (PZ) IMPROVES POST‐TBI NEUROPROTECTION
Rachel Hill, Deann Hopkins, James Pauly,
Univ. of Kentucky, Spinal Cord & Brain Injury Research Center, Lexington, USA
The aim of this study was to explore the hypothesis that interrupting TBI‐induced brain oxidative damage via a mechanistically complementary antioxidant combination of LP inhibition and scavenging of LP‐derived reactive carbonyls (4‐hydroxynonenal and acrolein) following a CCI‐TBI in male S‐D rats would improve motor and histological neuroprotective outcomes. To test this hypothesis, we investigated the antioxidant neuroprotective effects of acute administration of the 21‐aminosteroid (a ‘Lazaroid’) LP inhibitor 16‐desmethyl tirilazad (U‐74389G, a ‘Lazaroid’) or the LP‐derived carbonyl scavenger PZ, alone, and in combination, on motor functional and histological outcomes after TBI. S‐D rats (N = 9/group) received a severe (2.2 mm) controlled cortical impact (CCI)‐TBI. U‐74389G was administered i.v. at 15 min and 2 hrs post injury (hpi) followed by an intraperitoneal (ip) maintenance dose at 8 hpi at the following dose: 1 mg/kg (i.v) +3 mg/kg (i.p). PZ was administered ip at 15 min and 24 hpi at the following dose: 10 mg/kg +5 mg/kg. The neurological severity score (NSS; beam task) was performed on 1, 3 & 7 dpi and showed a significant improvement on day 3 post‐TBI in each of the drug‐treated groups compared to vehicle. Histological examination of the brains on day 17 post‐CCI‐TBI did not reveal significant cortical tissue sparing in rats treated with either U74389G or PZ alone, compared to vehicle. However, evaluation of the brains in the group that received the U74389G + PZ revealed a significant 50% reduction in cortical lesion volume. In conclusion, we found that early administration of U‐74389G + PZ to moderately severe CCI‐TBI rats resulted in an improved motor function and preservation of cortical brain tissue. Further studies are needed to optimize the combination ratio and treatment duration and define the therapeutic windows for single vs. combinatorial antioxidant drug therapy. This work was supported by NIH/NINDS R01 NS0083405, R01 NS084857.
Keywords: lipid peroxidation, traumatic brain injury, antioxidant, carbonyl scavenger, phenelzine, U‐74389G
β2‐ADRENORECEPTOR‐MEDIATED MITOCHONDRIAL BIOGENESIS IMPROVES SKELETAL MUSCLE MITOCHONDRIAL HOMEOSTASIS AND RECOVERY AFTER SCI
University of Arizona, Tucson, USA
In addition to local mitochondrial dysfunction, spinal cord injury (SCI) can result in deteriorated body composition, leading to decreased skeletal muscle mitochondrial activity and muscle atrophy. Treatment with the FDA‐approved β2‐adrenoreceptor (ADRB2) agonist formoterol has been shown to induce mitochondrial biogenesis (MB) in both the spinal cord and skeletal muscle and, therefore, has the potential to address comprehensive mitochondrial dysfunction following SCI. Female C57BL/6 mice were subjected to moderate contusion SCI (80 Kdyn) followed by daily administration of vehicle or formoterol beginning 8h after injury, a clinically relevant time‐point characterized by a 50% decrease in injury site mtDNA content. Formoterol treatment improved functional recovery in SCI mice compared to vehicle treatment by 7d post‐injury, as measured by the Basso‐Mouse Scale, with continued recovery observed through 21d (3.5 v. 2). SCI resulted in 15% body weight loss in all mice by 3d. Mice treated with formoterol restored pre‐surgery weight by 13d, while no weight gain occurred in vehicle‐treated SCI mice. Remarkably, formoterol‐treated mice exhibited a 30% increase in skeletal muscle mass compared to those treated with vehicle 21d post‐SCI (0.93 v. 0.72% BW), corresponding with increased MB and decreased skeletal muscle atrophy. Importantly, these effects were not observed in ADRB2‐/‐ mice subjected to SCI, indicating that formoterol is acting via the ADRB2 receptor. Furthermore, ADRB2‐/‐ mice depicted decreased spinal cord and skeletal muscle PGC‐1α expression, suggesting that ADRB2 may play a role in mitochondrial homeostasis under basal conditions. These data provide evidence for systemic ADRB2‐mediated MB as a therapeutic avenue for the treatment of SCI.
Keywords: mitochondrial biogenesis, skeletal muscle, formoterol, recovery
LY34864‐INDUCED MITOCHONDRIAL BIOGENESIS AND RECOVERY AFTER SPINAL CORD INJURY REQUIRES THE 5‐HT1F RECEPTOR
University of Arizona, Pharmacy, Tucson, USA
Spinal cord injury (SCI) is characterized by vascular disruption leading to ischemia, decreased oxygen delivery and loss of mitochondrial homeostasis. This mitochondrial dysfunction results in loss of cellular functions, calcium overload and oxidative stress. Pharmacological induction of mitochondrial biogenesis (MB) may be an effective approach to treat SCI. LY344864, a 5‐hydroxytryptamine 1F (5‐HT1F) receptor agonist, is a potent inducer of MB in multiple organ systems. To assess the efficacy of LY344864‐induced MB on recovery post‐SCI, female mice were subjected to moderate force‐controlled impactor‐induced contusion SCI followed by daily LY344864 administration. Decreased mitochondrial DNA and protein content was present in the injury site 3d post‐SCI. LY344864 treatment beginning 1hr after injury attenuated these decreases, indicating MB. LY344864 also increased locomotor capability, with treated mice reaching a Basso‐Mouse Scale (BMS) score of 3.5 by 21d, while vehicle‐treated mice exhibited a score of only 1.9. Importantly, knockout of the 5‐HT1F receptor blocked LY344864‐induced recovery. In addition, decreases in RNA expression of mitochondrial proteins and lack of LY344864‐MB induction were observed in naïve KO mice, indicative of disruption of mitochondrial homeostasis. Remarkably, a similar degree of locomotor restoration was observed when treatment initiation was delayed until 8hr after injury. Furthermore, cross‐sectional analysis of the spinal cord 21d after injury revealed decreased lesion volume with delayed LY344864 treatment initiation, emphasizing the potential clinical applicability of this therapeutic approach. These data provide evidence that induction of MB via 5‐HT1F receptor agonism may be a promising strategy for the treatment of SCI.
Keywords: spinal cord injury, mitochondiral biogenesis, serotonin receptor, LY344864
RESTORATION OF THE BLOOD‐SPINAL CORD BARRIER AFTER SPINAL CORD INJURY THROUGH 5‐HT1F RECEPTOR MEDIATED MITOCHONDRIAL BIOGENESIS
University of Arizona, Pharmacy, Tucson, USA
Vascular and mitochondrial dysfunction are well‐established consequences of spinal cord injury (SCI). Evidence suggests mitigating these dysfunctions may be an effective approach in treating SCI. We propose to mitigate the vascular and mitochondrial dysfunction following SCI through pharmacological induction of mitochondrial biogenesis (MB). We previously reported that 5‐hydroxytryptamine (serotonin) receptor 1F (5‐HT1F) agonism induces MB in the spinal cord and promotes locomotor recovery with drug initiation beginning at a clinically relevant time point of 8h post‐SCI. The goal of this study was to elucidate if MB induction can enhance restoration of the blood‐spinal cord barrier (BSCB) after SCI. C57BL/6J mice were subjected to moderate SCI using a force‐controlled impactor‐induced contusion model followed by daily administration of LY344864, a specific 5‐HT1F receptor agonist, (2 mg/kg, i.p.) beginning 1h after injury. Integrity of the BSCB was assessed using Evans Blue dye extravasation. SCI increased dye extravasation at 1, 3 and 7d, and LY344864‐treated mice displayed reduced dye accumulation at 7d post‐SCI, suggesting accelerated BSCB recovery. Levels of tight junction proteins occludin and zonula occludens‐1 were decreased in vehicle‐treated mice yet returned to sham levels with LY344864 treatment by d7. These findings led us to investigate if LY344864 induces MB in endothelial cells. C57BL6 primary cultures of cerebral microvascular endothelial cells were treated with LY344864 and a newer selective 5‐HT1F receptor agonist lasmiditan. A Seahorse Biosciences flux analyzer was used to quantify carbonylcyanide p‐trifluoromethoxyphenylhydrazone (FCCP)‐uncoupled oxygen consumption rate (OCR), a marker of MB. LY344864 and lasmiditan increased FCCP‐uncoupled OCR and mitochondrial protein levels. Collectively, these data reveal that 5‐HT1F receptor agonist‐induced MB occurs in endothelial cells and may accelerate restoration of the BSCB after SCI.
Keywords: mitochondrial biogenesis, spinal cord injury, blood spinal cord barrier, endothelial cells, tight junctions
PENTOBARBITAL USED AS ANESTHETIC DOES NOT PREVENT NON‐CONVULSIVE STATUS EPILEPTICUS IN RATS WITH SEVERE TRAUMATIC BRAIN INJURY
University of Eastern Finland, A.I. Virtanen Institute for Molecular Sciences, Kuopio, Finland
Acknowledgements: Academy of Finland, The Sigrid Juselius Foundation, and CONACYT.
Keywords: antiepileptic drugs, epileptogenesis, lateral fluid‐percussion injury, seizure, video‐EEG monitoring
PHARMACOKINETICS AND LOCOMOTOR EFFICACY OF RILUZOLE AND MINOCYCLINE COMBINATION IN SPINAL CORD INJURED RATS
1University of Houston, Department of Pharmacological and Pharmaceutical Sciences, Houston, USA
2University of Mississippi Medical Center, Department of Neurobiology and Anatomical Sciences, Jackson, USA
3Houston Methodist Hospital, Department of Neurosurgery, Houston, USA
Riluzole (R) and Minocycline (M) are promising candidates for spinal cord injury (SCI) treatment, based on current individual clinical trials in SCI patients. The combination treatment with R and M (R+M) is rational to target multiple pathological mechanisms. The study was to evaluate R + M treatment on pharmacokinetics (PK) of R and M, efficacy in locomotor activity, and PK/efficacy correlation in T10 SCI rat model.
The rats were treated with R,M, and R + M by oral R and i.v. M at 10 mg/kg, with the first dose at 3 hr post injury and then once daily for 14 days. Hind limb function was monitored using BBB locomotor rating scale, at 24hr, 48hr, 72hr, 5d, 7d, 10d and 14d post injury.
Plasma concentrations of R did not change during two‐week treatment in both R and R + M groups, but M concentrations on 14d were significantly higher than those at 72 hr and 7d, in both M and R + M groups. Plasma and spinal cord concentrations of M were significantly higher on 14d in R + M group than those in M group. The spinal cord to plasma (SC/P) ratios for R were 8.83 and 11.93 in R and R + M groups, respectively, and those of M were 1.16 and 1.23 in M and R + M groups, respectively. The BBB score improvement (%) was highest in R + M group upto 14d, and significantly higher on 5d and 10d in R + M group than M group. The R and M plasma concentrations showed positive correlations with BBB score improvement.
Riluzole and minocycline have distinct plasma and spinal cord PK profiles after spinal injury. The combination treatment showed merits over single agent treatments with increased minocycline exposures in plasma and spinal cord, and potentially improved therapeutic efficacy.
Support: Wings for Life
Keywords: Pharmacokinetics, Riluzole, Minocycline, Combination
REPOSITIONING FLUBENDAZOLE FOR SPINAL CORD INJURY
1University of Kentucky, Neuroscience, Spinal Cord and Brain Injury Res. Center (SCBIRC), Lexington, USA
2University of Kentucky, 2Department of Microbiology, Immunology & Molecular Genetics, Lexington, USA
We previously reported the serendipitous observation that Fenbendazole, a benzimidazole anthelmintic, improved functional and pathological outcomes following thoracic spinal cord contusion injury in mice when administered pre‐injury. Fenbendazole is widely used in veterinary medicine. However, it is not approved for human use and it was uncertain if only post‐injury administration would offer similar benefits. In the present study we evaluated post‐injury administration of a closely related, human anthelmintic drug, Flubendazole, using a rat spinal cord contusion injury model. Flubendazole, administered IP, 5 or 10 mg/kg day, beginning 3 hrs postinjury and daily thereafter for 2 or 4 weeks, resulted in improved locomotor function after contusion SCI compared to vehicle‐treated controls. Histological analysis of spinal cord sections showed that such treatment with Flubendazole also reduced lesion volume, improved total tissue sparing, white matter sparing, and gray matter sparing. Flubendazole inhibited the activation of GFAP, suppressed cyclin B1 expression and Bruton's tyrosine kinase activation, markers of B cell activation/proliferation and inflammation, and reduced B cell autoimmune response. Together, these results suggest the use of the benzimidazole anthelmintic Flubendazole as a potential therapeutic for spinal cord injury.
Keywords: Flubendazole, B cell‐directed therapy, Mild microtubule destabilization, Cyclin B1
ANTIOXIDANT NANOPARTICLES REDUCE THE BILATERAL SPREAD OF SECONDARY DAMAGE FOLLOWING CONTROLLED CORTICAL IMPACT IN MICE
1University of Nebraska, Biological Systems Engineering, Lincoln, USA
2Missouri University of Science and Technology, Materials Science and Engineering, Rolla, USA
Multifunctional nanoparticles provide the advantage of simultaneously targeting affected tissue, being tracked in situ through imaging, and delivering treatments. With the goal of promoting accumulation and retention in a TBI to reduce the spread of oxidative stress, we have developed oxygen reactive polymer, core crosslinked nanoparticles that can bind and inactivate reactive oxygen species in the thioether core while being imaged through magnetic resonance imaging (MRI). These nanoparticles rapidly accumulate within 1 hr and are retained for over 16 hrs in damaged brain in a mild controlled cortical impact (CCI) mouse model as determined through MR imaging of the tissue permeability coefficient, Ktrans. At 1 month post‐injury, CCI mice that received antioxidant nanoparticle treatment performed better in various behavioral tasks that assess hippocampal function including startle habituation and the Morris water maze as compared to untreated CCI mice. Furthermore, we found that antioxidant nanoparticle‐mediated improvement in spatial learning and memory was correlated with a reduced bilateral spread of neuroinflammation including reactive astrocytes, activated microglia, and neuron‐astrocyte‐microglia triads in the various subfields of the hippocampus. Our findings suggest nanoparticle‐mediated delivery may provide a more effective approach for improving target engagement and reducing the spread of secondary injury following a TBI.
Keywords: nanoparticle, thioether, antioxidant, reactive oxygen species, theranostic, Ktrans
PRECLINICAL EVALUATION OF NOVEL 20‐HETE FORMATION INHIBITORS TO AMELIORATE SECONDARY BRAIN INJURY
1University of Pittsburgh, School of Pharmacy, Department of Pharmaceutical Sciences, PITTSBURGH, USA
2University of Pittsburgh, School of Medicine, Department of Computational and Systems Biology, PITTSBURGH, USA
Mitigating secondary brain injury that occurs after traumatic brain injury (TBI), stroke or cardiac arrest is an important treatment strategy to prevent further brain damage. 20‐hydroxyeicosatetraenoic acid (20‐HETE), a potent microvascular constrictor, is a metabolite of arachidonic acid (AA) by cytochrome P450 (CYP) 4F2 and CYP4A11 in human. High cerebral spinal fluid 20‐HETE level is associated with three‐fold increased mortality in subarachnoid hemorrhage patients. Inhibition of 20‐HETE produces neuroprotection in TBI, stroke, and cardiac arrest preclinical models. These findings suggest that enzymatic inhibition of 20‐HETE formation is a potential therapeutic strategy to ameliorate secondary brain injury. To date, there is no inhibitor in the market as therapeutic intervention. Our objective is to develop novel druglike compounds and evaluate potency, selectivity, metabolic stability, CYP inhibition, and BBB permeability to aid lead optimization. Novel compounds were screened at 500nM in different microsomes: human liver microsome (HLM), recombinant CYP4F2, rat liver microsome (RLM) for inhibition against 20‐HETE formation. Compounds showed >50% inhibition in HLM were selected for preclinical evaluation. Potency was determined as IC50 in HLM and RLM. Selectivity was determined for 20‐HETE over epoxyeicosatrienoic acids and dihydroxyeicosatrienoic acids (EETs/DiHETs) formation. Microsomal stability was measured by disappearance of compound in HLM. CYP inhibition was determined by decrease in metabolites of probe substrates for five isoforms. 20‐HETE, EETs, DiHETs were analyzed by a validated UPLC‐MS/MS assay. BBB permeability was determined by MDR1‐MDCK permeability assay. The IC50 values of hit compounds 10, 19 were 443.4 and 187.1 nM, with over 200 times selectivity for EETs/DiHETs and low intrinsic clearance (13.8, 3.23 ul/min/mg protein) in HLM. In lead optimization phase, we identified eleven potent and selective compounds with IC50 < 100 nM and >100 times selectivity for EETs/DiHETs in HLM. Compounds had low intrinsic clearance (<14.88 ul/min/mg protein) in HLM. We found greater than 5‐fold species difference in potency between rats and humans. To summarize, we have identified different series of potent, selective, metabolically stable, highly BBB permeable compounds for in vivo evaluation of neuroprotection after brain injury.
Keywords: 20‐HETE, CYP4F, fatty acids, arachidonic acid, selective inhibitor, stroke
POST‐INJURY TREATMENT WITH BUPRENORPHINE‐SR‐LAB MINIMALLY AFFECTS DIFFUSE PATHOLOGIES FOLLOWING TRAUMATIC BRAIN INJURY IN THE RAT
1VCU, Anatomy and Neurobiology, Richmond, USA
2Godwin High School, Henrico, USA
Traumatic brain injury (TBI) is an increasingly common phenomenon, accounting for significant healthcare cost and adverse health effects. While there is information about focal pathologies following TBI, knowledge of more diffuse processes is lacking, particularly regarding how analgesics affect this pathology. This study investigates the effects of the opioid analgesic buprenorphine (Bup) on diffuse neuronal pathology, neuroinflammation, cell damage, and systemic physiology. We utilized a model of central fluid percussion injury (cFPI) in adult male Sprague‐Dawley rats treated with a single subcutaneous bolus of Bup‐SR‐Lab (1mg/kg) or equal volume saline 15min post‐injury (n = 6 animals per group). Microscopic assessments were performed in the left hemi‐thalamus and in layers V and VI of the lateral neocortex 1 day post‐injury. Neuroinflammation was assessed by analyzing Iba‐1+ microglial numbers and morphological alterations, including process length, number of branches, and number of end points per cell. Cell impermeable 10kDa dextrans were infused intraventricularly prior to sacrifice, and the percentage of total NeuN+ neurons demonstrating membrane disruption via uptake of dextran was determined. Axonal injury was assessed by investigating axonal transport disruption using immunohistochemical labeling for the anterogradely transported amyloid precursor protein (APP). Physiologic data showed no difference between groups except for significantly reduced weight loss in Bup treated animals compared to saline (3.4% and 6.5% loss compared to pre‐injury weight respectively; p = 0.013). There were no discernable differences in axonal injury or membrane disruption between groups. Microglia, however, revealed a decrease in cell number and morphological changes in the thalamus of Bup treated rats not appreciable in the cortex. These data suggest effects of Bup treatment on weight loss following cFPI and potential regional specificity of Bup‐associated microglial alterations, but very little change in other acute pathology at 1 day post‐injury. Overall, this preliminary study indicates that preclinical Bup use likely has little effect on acute pathology and can be used for analgesia following TBI in rodents. Funding: NNDS R01NS096143.
Keywords: Traumatic brain injury, Microglia, Weight changes, Buprenorphine
TRANSCRANIAL DIRECT‐CURRENT STIMULATION REDUCES IMPULSIVITY AFTER EXPERIMENTAL TBI
West Virginia University, Department of Psychology, Morgantown, USA
Survivors of TBI often experience impairments in cognitive function as well as chronic psychiatric‐like symptoms such as increased risky decision‐making and impulsivity. At this time, no treatment specific to this population has been developed. With the increased prevalence of deep brain stimulation (DBS) implants, neuromodulation has emerged as a major field with numerous promising applications. One such neuromodulatory technique for TBI is transcranial direct‐current stimulation (tDCS). While the precise mechanism of tDCS is debated, it effectively increases extracellular levels of dopamine in rats. Because alterations to dopaminergic signaling likely contribute to psychiatric dysfunction after TBI, tDCS has the potential to be a cost‐effective treatment option. In a set of studies our lab assessed the efficacy of cathodal tDCS treatment after a severe bilateral frontal controlled cortical impact injury model of TBI (AP/ML/DV: +3.0/+0.0/‐2.5 @ 3 m/s). In two studies, we established chronic deficits in impulsivity on two different behavioral tasks (Rodent Gambling Task, 5‐Choice Serial Reaction Time Task). We then demonstrate that tDCS, applied at 800 μA (32 A/m2 density) in 10‐min sessions 2‐hours prior to testing reduces impulsivity in the chronic post‐injury period (6+ weeks after injury). However, the tDCS effects were transient and dissipated once treatment was discontinued. These findings suggest that tDCS may indeed be an avenue for the treatment of long‐term cognitive problems that arise after TBI, but that more data are needed. Future studies will expand upon the mechanism to evaluate potential contributions of dopamine to this phenomenon and seek to extend the window of effect.
Keywords: Neuromodulation, Impulsivity
Poster Session Tuesday
B01 Astrocyte
MESENCHYMAL STEM CELL TRANSPLANTATION PROMOTES FUNCTIONAL RECOVERY THROUGH MMP2/STAT3 RELATED ASTROGLIOSIS AFTER SCI
1Kangwon national university hospital, Neurosurgery, Chuncheon, Korea South
2Kangwon national university, Neurosurgery, Chuncheon, South Korea
3Kangwon national university, Applied animal science, Chuncheon, South Korea
Keywords: acute Spinal cord injury
EXAGGERATED PROLIFERATIVE RESPONSES IN THE SVZ FOLLOWING CLOSED HEAD INJURY IN LIF HAPLODEFICIENCY MICE
Rutgers University, Physiology, Pharmacology, Neuroscience/ Biomedical Engineering, Newark, USA
Supported by CBIR17IRG019 from the NJCBIR awarded to SWL.
Keywords: Closed Head Injury, Stem Cells, Astrocytes, Leukemia Inhibitory Factor
ASTROCYTE‐SPECIFIC GENE EXPRESSION AFTER MILD REPETITIVE CLOSED HEAD INJURY
1UCLA, Neurosurgery, Los Angeles, USA
2Physiology, UCLA, Los Angeles, USA
3Psychiatry and Biobehavioral Sciences, UCLA, Los Angeles, USA
4Neurobiology, UCLA, Los Angeles, USA
Repetitive concussions can lead to learning/memory deficits, particularly if the number of concussive impacts occur within a short time period. Glial biology remains an understudied area of TBI research and multiple lines of evidence suggest that TBI‐induced changes in astrocyte function are part of the pathology of the disease process, and that the underlying molecular signaling systems represent a target for recovery approaches. Toward a causal analysis of that goal, the objective of this study was to probe for genetic alterations within astrocytes, following a variable number of repetitive closed head injury (rCHI) impacts. Aldh1l1‐Cre/ERT2 BAC transgenic mice were used to investigate astrocyte‐specific genetic changes in response to single or multiple concussive impacts (1, 2, 5 @ 24hrs apart) in an rCHI mouse model. A controlled cortical impact device (5mm diameter impactor tip), centered midline over Bregma was used to produce rCHIs. Bilateral, dorsal hippocampal tissue was harvested for RNA immunoprecipitation at 24 hrs after 5 rCHIs (n = 4), 5 days after 1 rCHI (n = 5), and 4 days after 2 rCHIs (n = 4). We observed upregulation of 1230 genes (including: Mir544, Aqp1, Aqp7, Pdzk1ip1, Prr15l, Lrrc52, Zscan10, Igf2, Col4a3, Col8a1, Col18a1, Bmp4, Thbs1, Angptl2, Calml4, S100a9, Angptl2, Cldn1, Kcne2, Olfr570, Olfr574) and downregulation of 107 genes (including: Gal3st3, Scube2, Lars2, Gal3st3, Tac2) within hippocampal astrocytes in response to 5 rCHIs versus Sham (n = 4) animals. With our injury centered between medial prefrontal cortex and hippocampus, we postulate that astrocyte‐specific genetic alterations within the hippocampus will correlate with hippocampal neuronal cell death and learning/memory deficits. These results demonstrate a potential new therapeutic target for repetitive concussive injury. Support: UCLA Clinical and Translational Science Institute UL1TR001881.
Keywords: Astrocyte Injury Defined (AID) Biomarkers, MRI, TBI, Barnes maze, CCI
MRI CORRELATES OF ASTROCYTE‐DEFINED BIOMARKERS OF TRAUMATIC BRAIN INJURY: A TOP‐NT CONSORTIUM PROJECT
1Neurosurgery, UCLA, Los Angeles, USA
2IDDRC‐Semel Institute, UCLA, Los Angeles, USA
In the absence of gross anatomical abnormalities on MRI it is difficult to diagnose mild TBI. Glial biology is a complex, yet understudied area of TBI pathology that may provide useful indicators of injury diagnosis and prognosis. The objective was to quantify blood and CSF for Astrocyte Injury Defined (AID) biomarkers of pathology, and determine any correspondence to whether MRI‐specific parameters of pathology and injury severity correlate at acute time‐points after experimental TBI. A controlled cortical impact or sham injury was conducted in male and female adult rats and blood was collected from the tail vein at 30mins and 1.5hrs. Structural and cerebrovascular MRI data sets were acquired at 3hrs post‐injury/sham (n = 11,12, injured, sham) followed by measurement of tissue metabolism at 6hrs in hippocampus, thalamus, and cortex using a mitochondrial respiration assay. Longitudinal MRI data were acquired at 3 and 24hrs post‐injury/sham (n = 11,9, injured, sham) to assess tissue swelling/atrophy (T2‐weighted‐structural), microstructural changes (2‐shell, diffusion‐weighted imaging (DWI)), blood‐related products (multi‐echo‐T2*susceptibility‐weighted imaging) and cerebral blood flow (FAIR technique). Final terminal blood and cerebrospinal fluid were obtained in all rats at termination and analyzed with all biofluids for AID biomarkers. MRI DWI data were fit to the diffusion tensor and kurtosis models to derive indices of microstructural abnormalities. T2 data were analyzed by tensor‐based‐morphometry for unbiased delineation of early tissue swelling or atrophy. Echo‐averaged, T2*data and DWI‐derived indices were analyzed by comparison to population templates constructed across the entire study and interrogated for subject level “injury burden”, the volume of abnormal tissue related to haem load or microstructural disturbance. MRI data were tested for correlation to AID biomarkers. Analysis of glial pathology resulting from this multi‐parameter, multi‐time‐point study should aid in diagnosing/predicting outcome after TBI. Support: NIH‐UG3NS106945.
Keywords: TBI, Barnes maze, MRI, Astrocyte Injury Defined (AID) Biomarkers
ASTROCYTE INJURY‐DEFINED (AID) BIOMARKER ASSAYS FOR PRECLINICAL NEUROTRAUMA MODELS AND DIAGNOSTIC MONITORING OF TBI PATIENTS
1UCLA, Semel Institute, IDDRC, Los Angeles, USA
2Brain Box Solutions Inc, Richmond, USA
3EnCor Biotechnology, Gainesville, USA
4UCLA, BIRC, Department of Neurosurgery, Los Angeles, USA
Diagnosis, monitoring and outcome prediction are essential for translating novel TBI treatments from rodent to man. Our objective was to develop and validate immunoassays for quantitative assessment of novel Astrocyte Injury Defined (AID) neurotrauma biomarkers useful for both animal models and TBI patients. AID biomarkers include Aldolase C (ALDOC), brain fatty acid binding protein 7 (FABP7) and small breakdown products of glial fibrillary acidic protein (sGFAP‐BDP, Halford et al., 2017). Species‐differences exist for biofluids, and biomarker protein sequences and kinetics. We established species‐specific cerebrospinal‐fluid (CSF) and serum preparations and validated both assay standards and novel AID biomarkers antibodies. Serum albumin depletion was optimized using albumin‐binding magnetic beads for rat serum, and immunoaffinity columns for human serum, while retaining biomarkers in eluates. Custom‐antibodies to AID biomarkers were each validated separately for specificity and sensitivity using rat and human analytes, and recombinant proteins. Antibody specificity was determined using tissue lysates, dilution studies, recombinant biomarkers, isoforms and similar proteins using antigen‐antibody‐microarrays and western blotting. The best performing antibody pairs were then selected for mesoscale discovery platform (MSD) assay prototypes. Rodent AID biomarker detection was optimized by pre‐adsorbing antibodies with rat immunoglobulins before interrogation in immunoassays. The assays detected injury‐specific elevation of AID markers in CSF and serum after rat controlled cortical impact compared to sham samples. Pilot biomarker kinetic studies showed elevated ALDOC, GFAP and FABP7 at 1.5hrs post‐injury, while BDPs of ALDOC and GFAP accumulated by 24hrs post‐injury. These studies provide critical authentication of custom‐made antibodies for translational neurotrauma models and enable future clinical diagnosis and prognosis for TBI patients.
Support: NIH 1UG3NS106945‐01, UG3‐TOP‐NT consortium (NGH, IBW), NINDS SBIR grant 1R43NS106972‐01 (TVM, IBW), BRAINBox Solutions, Inc.
Keywords: translation, serum, csf, controlled cortical impact, outcome, breakdown product
EXAMINING CD44 AS A NOVEL MARKER FOR REACTIVE ASTROGLIOSIS FOLLOWING TBI
1University of Kentucky, Sanders‐Brown Center on Aging, Lexington, USA
2University of Kentucky, Neuroscience, Lexington, USA
The current knowledge base regarding the pathobiological contribution of reactive astrogliosis in the brain following traumatic brain injury is poorly understood. To begin to understand astrocyte‐specific response to TBI, we examined a time course spanning acute‐subacute intervals following TBI; 1, 3, and 7 days post‐surgery using 3‐month‐old C57BL6/J mice that received either sham or controlled cortical impact (CCI) contusion surgery. Two cohorts were generated; one for histological quantification and a second for gene expression profiling. Reactive astrogliosis was quantified using GFAP, S100beta, and Aqp4 as histological markers. Secondly, at the prescribed interval, ipsilateral neocortex and dorsal hippocampus was used for ACSA‐2 magnetic bead astrocyte enrichment. Enriched astrocytes were subsequently processed for RNA isolation, cell enrichment validation, and finally gene expression. Astrocyte‐specific response to TBI was profiled using a focused array of 46 genes. Our time course profiling revealed that the bulk of disparate responses occurred at the 3d interval, notably exacerbated expression of CD44, relative to sham. Gene profiling was examined using principle component analysis (PCA) and hierarchical clustering, revealing conserved groupings between each surgical cohort. As an extension; to examine the molecular underpinnings of CD44+astrocytes, we used our novel astrocyte‐specific conditional reporter strain (Ai9DAldh1l1CreERT2 ) which fluorescently labels all CNS astrocytes with tdTomato following tamoxifen administration. Using these reporter mice, 3 months old, we examined the 3d post‐surgery interval (sham and TBI) via FACS of CD44+astrocytes (e.g. CD44+tdTomato+) versus CD44neg.tdTomato+astrocytes. Sorted cells were again processed for RNA isolation and analyzed on the same focused gene array as above. Our current data indicate that TBI‐induced CD44+reactive astrocytes acquire a predominantly pro‐inflammatory response (e.g. CCL2), with a concomitant decrease in genes associated with synaptic support (e.g. GPC6), compared to CD44neg.astrocytes. Collectively, our findings identify a novel subset of astrocytes that may play an integral role in the deleterious neurodegenerative sequelae following TBI, highlighting these cells as a potential therapeutic target.
Keywords: Astrocyte, Closed Cortical Impact, Inflammation
B02 Behavioral Function
ALLEVIATE IMPULSIVE BEHAVIOR WITH HIPPOCAMPAL‐HYPOTHALAMIC CIRCUIT MANAGEMENT AFTER TRAUMATIC BRAIN INJURY
Indiana University School of Medicine, Neurological Surgery, Indianapolis, USA
In USA, traumatic brain injury (TBI) is a serious public health problem with high incidents, high death rate and high cost. Longitudinal studies showed that TBI patients are shown to associate with long‐term deficits. These long‐term effects range from personality change to diagnosed psychiatric disorders and may last for up to 10 years or for lifetime. Among all the symptoms, impulsivity serves as an important component of a lot of disorders, like ADHD, CODD, and is complaint by a large proportion of TBI patients' families. Recently a serial of published papers identified the hippocampal‐hypothalamic circuit which was involved in anxiety vs. impulsivity regulation. In our CCI model, moderate TBI mice showed dramatic increase of impulsivity along with the significant decrease of neuronal activity in both lateral hypothalamic area (LHA) and ventral hippocampal CA1 (vCA1) region. It suggested the reduction of neuronal activity in LHA and vCA1 may contribute to the increase of impulsivity after TBI. In elevated plus maze (EPM) test, by using Dreadd system, we manually increased the neuronal activity in vCA1 and in turn remarkably decrease the time and the distance that treated TBI mice spend and travelled in open arm comparing to the none‐treated TBI group. The results suggested increase of neuronal activity in vCA1 attenuated the impulsive behavior in TBI mice after injury. Same results was obtained in open field test either. Altogether, chemic‐genetically active hippocampal‐hypothalamic circuit alleviate the mice impulsivity after TBI and suggested the neural circuit is the potential target for effective TBI treatment.
Keywords: TBI, impulsivity, neural circuit, chemogenetics
A CD1D DEFICIENCY IN MICE PROMOTES FUNCTIONAL RECOVERY AFTER A SPINAL CORD INJURY
1Indiana University School of Medicine, Neurological Surgery, Indianapolis, USA
2IUSM, Microbiology and Immunology, Indianapolis, USA
CD1d is a glycoprotein expressed on the surface of various antigen‐presenting cells. CD1d presents lipid antigens to a subpopulation of innate T cells, natural killer T (NKT) cells. The CD1d/NKT cell axis plays an important role in inflammation which may exacerbate spinal cord injury (SCI)‐induced consequences. Here we investigated whether a CD1d deficiency could reduce inflammation and promote functional recovery after a SCI. The thoracic 10 contusive SCIs were performed on adult C57BL/6 wildtype (WT) and CD1d knockout (KO) mice. Inflammatory responses to acute SCI were analyzed by ELISA, flow cytometry, real time RT‐PCR and immunofluorescence. Functional recoveries were assessed with a combination of the Basso Mouse Scale (BMS), grid‐walking, rotarod and transcranial magnetic‐motor evoked potential (tcMMEP). Histological assessments included the lesion area and spared white matter after staining with Cresyl Violet‐Eosin and Luxol Fast Blue, respectively. Our results show that SCI induced NKT cell activation at 1 day post‐injury, and CD1d mRNA expression increased at 3 and 7 days post‐injury in WT mice. A CD1d deficiency significantly reduced the production of pro‐inflammatory cytokines (e.g. IL‐1, IL‐6 and TNF‐α), decreased microglia/macrophage numbers by 54%, and increased neuron survival surrounding the lesion area. A CD1d deficiency significantly increased BMS scores starting from 1 week and up to 4 weeks post‐injury. A CD1d deficiency also significantly reduced foot drop rate, and prolonged the latency on the rotarod test. A CD1d deficiency significantly protected descending axonal pathways by 81% in KO mice as compared to 43% in WT mice. The lesion area in CD1d‐deficient mice was reduced by 47%, and the spared white matter area was increased by 38%, respectively, as compared to WT mice. These data strongly suggest that a CD1d deficiency can remarkably reduce inflammation, decrease neuronal loss and tissue damage, and promote functional recovery after SCI.
Keywords: spinal cord injury, CD1d, inflammation, functional recovery, knockout mice
IMPROVING DETECTION OF REDUCED NEUROLOGICAL FUNCTION IN A LARGE ANIMAL MODEL OF SEVERE BRAIN INJURY
Massachusetts General Hospital, Harvard Medical School, Neurosurgery, Boston, USA
Hemispheric hypodensity (HH) is a severe form of traumatic brain injury (TBI) often associated with abusive head trauma, where children often have evidence of an impact, a subdural hematoma (SDH), seizures, apnea and destruction of the cortex underlying the SDH. Our model of unilateral HH includes focal injuries (cortical impact, mass effect, SDH, kainic acid‐induced seizures) and global insults (apnea and hypoventilation). One week (“infants”) and one‐month‐old piglets (“toddlers”) are comparable to human infants and toddlers respectively in brain maturation and morphology. “Toddlers” had more hypoxic‐ischemic‐type injury with vasogenic edema that was unilateral, while “infants” exhibited less damage that was bilateral. Our hypothesis was that the neurological exam we previously validated in “toddlers”, which included both global and motor domains, would detect neurologic deficit in both ages. At 8 hours post‐injury, both “infants” and “toddlers” had reduced neurological scores compared to shams. Additionally, “infants” scored lower than “toddlers” (P = 0.002) potentially due to their bilateral damage pattern. At 20 hours post‐injury, although a main effect of injury was still present (P < 0.05), neither “infants” nor “toddlers” scored lower than shams despite a subset that were unable to be extubated and/or exhibited motor deficits, indicating that our current neurological exam lacked sensitivity. Therefore, a neurological assessment was developed to detect the full range of neurological deficits in swine. This new exam assesses additional neural and motor domains along a continuum of impairment rather than on a binary “present” or “absent” determination, potentially improving sensitivity in pigs with less profound deficits. A comprehensive neurological exam to evaluate piglets after severe TBI will benefit future studies evaluating pathophysiology and potential therapeutics.
Keywords: Neurological assessment, Hemispheric hypodensity, Abusive head trauma, Neurological deficit, Subdural hematoma, Swine model
IMPAIRED FUNCTIONAL OUTCOME AFTER CONTROLLED CORTICAL IMPACT IN RIPK3 KINASE DEAD AND MLKL KNOCKOUT MICE
Massachusetts General Hospital, Pediatrics, Charlestown, USA
Keywords: necroptosis, blood brain barrier
GETTING SLAMMED: THE EFFECTS OF ACUTE AND CHRONIC ALCOHOL CONSUMPTION ON TBI OUTCOMES IN LATE ADOLESCENT FEMALE RATS
1Monash University, Melbourne, Australia
2University of Calgary, Calgary, Canada
Adolescence represents a period of dramatic change in nearly every facet of life, but particularly in neurological structure and function. Differences in maturation rates of various brain structures make risky behaviours more alluring for adolescents. Alcohol use, particularly binge drinking, is prevalent amongst adolescents and young adults. Research suggests that females are more susceptible to the detrimental effects of alcohol. While alcohol consumption itself may incur a risk of neurological damage, it's also a significant risk factor for traumatic brain injury (TBI). TBI among adolescents is described as a modern healthcare epidemic within North America. The drastic changes occurring within their neurological networks put them at a greater risk for developing long‐term post‐traumatic deficits. Recent studies have indicated contradictory findings regarding the effects of alcohol consumption on TBI outcomes in adults, with some studies indicating detrimental effects while others suggest neuroprotective abilities. However, little is known about the effects of alcohol consumption on TBI outcomes during the sensitive stage of adolescent development. Late adolescent female Sprague Dawley rats were randomly assigned to one of six experimental conditions: Pre‐injury alcohol+mTBI (8F); Pre‐injury alcohol+Sham (8F); Pre‐ and Post‐injury alcohol+mTBI (8F); Pre‐ and Post‐injury alcohol+Sham (8F); No alcohol+mTBI (8F); No alcohol+Sham (8F). The alcohol consumption groups received a 10% w/v ethanol solution in an amount based on the animals' weight. Following the injury, the rats were subjected to a behavioural test battery, which included beamwalking, elevated plus maze, openfield, novel context mismatch, and forced swim, to assess post‐concussive symptomology. Overall, alcohol consumption at the time of TBI significantly (p < .05) improved motor coordination and balance and decreased depressive‐like behaviours in comparison to the sham animals that consumed alcohol, while alcohol consumption in general significantly (p < .05) decreased anxiety‐like behaviours. Thus, the results suggest that alcohol may exhibit neuroprotective abilities in the context of adolescent TBI.
Keywords: mTBI, Alcohol Consumption, Adolescence, Rat Model, Post‐Concussive Symptomology, Neuroprotection
KETOSIS IMPROVES PROGNOSIS: THE EFFECTS OF THE KETOGENIC DIET ON MILD TRAUMATIC BRAIN INJURY IN ADOLESCENT RATS
1Monash University, Melbourne, Australia
2University of Calgary, Calgary, Canada
A mild traumatic brain injury (mTBI) is caused by an insult to the head and may result in transient neurological dysfunction. A proportion of individuals have prolonged clinical and cognitive symptoms, referred to as post‐concussion symptomology (PCS). Interestingly, the biphasic nature of these injuries is less publicly recognized. The resulting cascade of molecular imbalance that follows initial impact includes altered glucose metabolism, mitochondrial dysfunction, and increase in reactive oxygen species (ROS). Glucose is the primary energy source for the brain, however following brain injury glucose becomes an inefficient energy substrate, and the brain is primed to use alternative substrates for cerebral function. The ketogenic diet (KD), a high fat, low carbohydrate diet, forces the body to burn fat rather than carbohydrates thus utilizing ketones over glucose for energy. Ketones can supply up to 70% of the energy required for brain function, improve mitochondrial metabolism, and reduce production of ROS. Given that mTBIs are commonly experienced during adolescence, a period in which significant brain growth and maturation occurs, our study sought to examine the effects of the KD on PCS in adolescent rats. Male and female Sprague Dawley rats were randomly assigned to receive either a standard diet (n = 23), or the KD – either pre‐injury (n = 16) or post‐injury (n = 27), then further randomized into a sham (n = 30) or mTBI (n = 36) condition. All animals were then tested on 6 behavioral tasks validated to examine PCS. Gene expression analysis in the brain and gut were performed following sacrifice. Exposure to the KD prior to injury had some neuroprotective properties, improving short‐term working memory p < .05. The KD post‐injury may have been therapeutic, reducing both anxiety‐ and depressive‐like behaviours p's < .05. The KD also altered gene expression in the hypothalamus, prefrontal cortex, hippocampus and intestine p's < .05. This study demonstrates the promise of the KD as both a neuroprotective and therapeutic agent for mTBI and warrants further investigation.
Keywords: mTBI, Post Concussion Symptomology, Ketogenic Diet, Adolescence, Rat Model, Microbiome
ACUTE POSTCONCUSSIVE SYMPTOM DOMAINS AND MRI FOLLOWING MILD TRAUMATIC BRAIN INJURY
1National Institutes of Health, Nursing Research, Bethesda, USA
2National Institutes of Health, Neurological Disorders and Stroke, Bethesda, USA
In the United States, 42 million patients seek care for traumatic brain injuries (TBIs) every year, with over 90% of injuries classified as mild TBI (mTBI). One of the most common symptoms of mTBI is postconcussive symptoms (PCS). Determining who will and will not have long term symptoms is vital to improving outcomes. Imaging, such as MRI, may provide insight into underlying mechanisms of PCS. The aim of this study was to examine the association between PCS and MRI findings within 48 hours of injury.
Keywords: Postconcussive Symptoms, Neurobehavioral Symptom Inventory, MRI, Recovery
DAILY ADMINISTRATION OF PREBIOTIC INULIN AFTER JUVENILE TRAUMATIC BRAIN INJURY
Southern Illinois University, Psychology, Carbondale, USA
Juvenile traumatic brain injury (jTBI) is a public health problem in the United States and is one of the main causes of death and disability in children and adolescence. Recently, evidence of a bidirectional relationship between the gut microbiota and the brain, known as the gut‐brain axis, has shown to play an essential role regulating gastro‐intestinal, cognitive, and behavioral functions. Manipulation of this complex relationship will allow for the potential to develop approaches for treatments that ameliorate cognitive and behavioral dysfunction commonly associated with jTBI. As dietary supplements have been regarded as potential treatment candidates that can impact the gut‐brain axis, the current study used the prebiotic oligofructose‐enriched inulin. Inulin, in particular, has been shown to promote healthy gut bacteria. The current study hypothesized that daily administration of inulin would lead to functional improvement following injury. Male Sprague‐Dawley juvenile aged rats were injured at post‐natal day 28, age approximate to humans 4‐11 years old. Subjects received a moderate CCI over the parietal cortex and were administered 500mg/kg of inulin (via oral gavage) daily. Motor deficits were assessed on the foot fault task during the first week following injury, after which a battery of cognitive tasks, including novel object recognition (post‐injury day 7), Morris water maze (post‐injury day 14), and the radial arm maze (post‐injury day 22) were given. Contrary to the predicted outcome, the inulin‐treated subjects did not show improvement over the vehicle‐treated‐group on tests utilized. As prior work by our lab and others have shown that injury induces gut microbiota dysfunction, it is possible that complex gut microbiota related mechanisms after TBI may be interfering with or reducing the efficacy of dietary supplements such as inulin. Future research from our lab will examine any potential dose‐response related mechanisms using inulin to find optimal dosage parameters.
Keywords: Juvenile TBI
INTESTINAL DYSBIOSIS EXACERBATES BEHAVIORAL OUTCOMES AND PATHOLOGY AFTER TRAUMATIC BRAIN INJURY IN THE JUVENILE RAT
1Southern Illinois University, Psychology, Carbondale, USA
2Southern Illinois University, Microbiology, Carbondale, USA
Humans coexist in a mutually beneficial relationship with the gut microbiome, a collection of microorganisms that reside within the intestinal system. The intestinal microbiome is the best characterized microbial population within the body and communicates with the central nervous system (CNS). This communication is through the microbiome‐gut‐brain axis (MGBA), a bidirectional communication system that utilizes neural, hormonal, and immunological signals. Through the MGBA, the CNS influences gastro‐intestinal function and microbial content while the gut microbiota signals to the CNS affecting stress, anxiety, and learning. Evidence indicates that disrupting the gut microbiome (dysbiosis) impairs motor function, decreases synaptic plasticity, and exacerbates lesion size. However, it is unknown how dysbiosis affects neurobehavioral function following juvenile traumatic brain injury (jTBI). The current study explored the hypothesis that intestinal dysbiosis at the time of injury negatively impacts functional recovery and neuropathology after jTBI. Male and female Sprague‐Dawley rats were given an antibiotic cocktail via drinking water for one week prior to injury and fecal matter was collected daily. After injury (PND‐28), animals were returned to standard drinking water and assessed for functional recovery using the novel object recognition task, Morris water maze, and radial arm maze. Neuropathology was assessed through lesion size and microglial activity. Results demonstrated that intestinal dysbiosis exacerbates impairments in a sex‐dependent manner. Female rats with induced‐dysbiosis demonstrated worse outcomes in spatial navigation and decision making compared to non‐dysbiosis counterparts whereas males failed to show this effect. Induced‐dysbiosis females also showed larger lesion sizes and increased microglia compared to non‐dysbiosis females with this effect not present in males. These findings implicate a previously unknown role of gut bacteria in influencing functional recovery and pathophysiology after jTBI in a sex dependent manner. Future research will explore the role of the observed sex differences in how the microbiome influences recovery following jTBI.
Keywords: microbiome, sex, dysbiosis, gut‐brain axis
INTRANASAL INSULIN IMPROVES COGNITIVE FUNCTION AND REDUCES ANXIETY‐LIKE BEHAVIOR IN MILD TRAUMATIC BRAIN INJURY
1Uniformed Services University, Anatomy, Physiology and Genetics, Bethesda, USA
2Uniformed Services University, Center for Neuroscience and Regenerative Medicine, Bethesda, USA
3Uniformed Services University, Translational Imaging Core, Bethesda, USA
4HealthPartners Neuroscience Research, St Paul, USA
After a traumatic brain injury (TBI), including mild TBI (mTBI), there is an increased risk of cognitive deficits and anxiety disorders. Previously, we have shown that intranasal insulin can reduce post‐injury cognitive deficits after a moderate TBI. In this study, we aimed to examine the therapeutic effect of intranasal insulin treatment on cognitive function and anxiety in mTBI. Adult male Sprague‐Dawley rats underwent a mild lateral fluid percussion injury and received daily intranasal administration of insulin or saline from 4 hours to 14 days post injury. Positron emission tomography (PET) scans were conducted on days 2, 4, and 10 post injury to examine post‐injury glucose uptake in the brain. Unlike our previous studies, we observed no change in glucose uptake in insulin treated animals. Cognition was examined with the Morris water maze (MWM) on post injury days 11‐14. The MWM test showed a significant impairment in memory function, demonstrated by significant alteration of search strategy in saline‐treated, but not insulin‐treated, mTBI rats. To test anxiety‐like behavior, a series of tests were performed. Saline treated mTBI rats had both significantly increased grooming time in the perimeter and decreased time in the center compared to the insulin treated group. In the light dark box test, rats treated with saline had significantly fewer entries into the light area than insulin treated rats. These data demonstrate that mild TBI causes significant cognitive impairments and induces anxiety‐like behavior. Administration of insulin through 14 days post‐injury led to a significant reduction in these behaviors, providing support for a therapeutic use of insulin in mTBI.
Acknowledgements: This work is funded by the National Institutes of Health/NINDS (grant number 1 R21 NS095116‐01A1) and the CNRM at the Uniformed Services University.
Keywords: Insulin, Intranasal, Lateral Fluid Percussion, Anxiety, Memory
DEVELOPMENT OF A REALISTIC BRAIN INJURY MODEL IN A GYRENCEPHALIC ANIMAL
USUHS, CNRM, Bethesda, USA
During combat, frequent exposure to blast waves is often accompanied with ongoing stress and combined with other types of brain injuries. In this study, we attempted to develop a more realistic model of combat‐related brain injury that mimics multiple and repetitive brain injuries plus stress. Our studies use the smallest mammal with a gyrencephalic cortex, the ferret, which allows an easier comparison with the human brain. The ferret brain contains sulci and gyri, a substantial amount of white matter, and a ventrally positioned hippocampus. Our study included multiple blast and rotational head injuries (CHIMERA) accompanied by random stressors over a period of several weeks. Six‐month‐old male ferrets survived for an additional 4‐5 weeks and were tested for behaviors that addressed conditions known to be associated with TBI, including headache, sleep disturbances, and depression. Our groups included Sham, Injuries alone, and Injuries + Stress. The results revealed differences between the groups pre and post injury. For tests involving motor behavior we observed reduced speed and distance traveled when compared with their pre values in the Injury and Injury + Stress groups, in contrast to the Sham group. In socialization tests, the 2 injured groups preferred to spend more time with familiar animals than the Sham group. We also saw interesting changes in overall measures of activity. Actigraphs established that the activity configuration of each group was distinctly different, suggesting impaired patterns of sleep and general activity in both the Injury and Injury + Stress groups. More subtle impairments were observed with an overnight memory task of object recognition and in the amount of eye contact established with the investigator in the Injury + Stress group only. The Injury + Stress group also preferred to spend more time in a dark environment compared with the Sham and Injury only animals. Although preliminary, these observations suggest that animals undergoing stress and injury demonstrate behavioral changes that relate to headache, impaired sleep, and depression.
Funded by CNRM‐Ferret Core.
Keywords: CHIMERA, Actigraph, Socialization, Ferret
A NOVEL GLYCOSYLATED PITUITARY ADENYLATE CYCLASE‐ACTIVATING PEPTIDE ATTENUATED FUNCTIONAL DEFICITS FOLLOWING EXPERIMENTAL TBI
1University of Arizona College of Medicine‐Phoenix, Department of Child Health, Phoenix, USA
2BARROW Neurological Institute at Phoenix Children's Hospital, Phoenix, USA
3University of Bath, Bath, UK
4University of Arizona, Chemistry and Biochemistry, Bio5, Tucson, USA
5Phoenix VA Healthcare System, Phoenix, USA
Pituitary adenylate cyclase‐activating peptide (PACAP) is an endogenous peptide hormone released by the hypothalamus and adrenal gland. Therapeutically, PACAP has efficacy to reduce axonal injury, enhance neurogenesis and angiogenesis, and provide additional neuroprotective effects following traumatic brain injury (TBI). However, the physical properties of PACAP impair bioavailability at the target tissue. To overcome this, we have developed a novel glycosylated PACAP (GPACAP) with improved stability and bioavailability that is capable of easily crossing the blood brain barrier. We hypothesized GPACAP would reduce inflammation and inflammation‐induced sleep, and attenuate behavioral deficits following diffuse TBI in the mouse. Adult male and female C57BL/6J mice were subjected to midline fluid percussion or sham injury and administered GPACAP (10mg/kg, i.p.) or saline 30min prior to injury (shams n = 21, TBI‐saline n = 18, TBI‐GPACAP n = 17). TBI induced acute sleep regardless of treatment (F(2,51) = 3.69, p = 0.03). Motor deficits measured by rotarod were present at 2, 5, 7 days post‐injury (DPI) (F(2,54) = 7.43, p = 0.0014); TBI‐saline and TBI‐GPACAP groups had shorter latencies to fall off the rotarod compared to uninjured shams. TBI induced functional deficits as assessed by the neurological severity score (NSS) task at 2DPI (KW = 35.47, p < 0.0001), 5DPI (KW = 24.57, p < 0.0001), and 7DPI (KW = 12.54, p < 0,0019). TBI‐saline mice had higher NSS scores compared to sham at 2, 5, 7DPI, but TBI‐GPACAP mice recovered function by 7DPI. There were no injury‐induced deficits measured at 14 and 15DPI on open field task, novel object recognition, elevated plus maze, or tail suspension. Flow cytometry and cytokine analyses are ongoing to investigate if GPACAP attenuated. Thus, GPACAP accelerated recovery of function following TBI and should be further explored as a therapeutic candidate for neurological injury.
Funding: PCH‐Mission‐Support, R01NS091238
Keywords: Pituitary Adenylate Cyclase Activating Peptide, mTBI, Glycosylation, PACAP
ACUTE COLITIS FOLLOWING CHRONIC TRAUMATIC BRAIN INJURY IN MICE INDUCES PERSISTENT NEUROBEHAVIORAL DEFICITS
1University of Maryland, Baltimore, Baltimore, USA
2NIH, Bethesda, MD
Keywords: brain‐gut, colitis, TBI, behavior
EF‐24 PHARMACOTHERAPY IMPROVES NEUROLOGICAL FUNCTION AND ANXIETY DETECTED 1 DAY POST TRAUMATIC BRAIN INJURY AND HEMORRHAGIC SHOCK
1University of Oklahoma Health Sciences Center, Pharmaceutical Sciences, Oklahoma City, USA
2Oklahoma Center for Neuroscience, Oklahoma City, USA
3University of Oklahoma Health Sciences Center, Department of Surgery, Oklahoma City, USA
4Oklahoma City VA Medical Center, Oklahoma City, USA
Traumatic brain injury (TBI) is a leading cause of death and disability in Americans younger than 40 years old. The extent of primary brain damage and recovery from a TBI is further complicated by hemorrhagic shock (HS). Combined TBI + HS polytrauma is experienced with high morbidity and mortality in US military service members. To date, treatment of TBI + HS remains palliative and rehabilitative. Our main objective was to determine the neuroprotective effect of EF‐24 therapy on neurobehavioral deficits induced by a combined TBI + HS polytrauma model in rats. Sprague Dawley rats (male and female) received either vehicle, EF‐24 and/or blood transfusion treatment 1 hr following a mild TBI delivered by a controlled cortical impact with or without HS induced by 50% blood volume withdrawal 15‐30 min post‐TBI. Rats were assessed for neurological deficits and anxiety one day following TBI ± HS using the modified neurological severity score and elevated plus maze respectively. EF‐24 treatment seemed more effective in rats injured by combined TBI + HS polytrauma than rats injured by single TBI trauma. EF‐24 treatment of rats injured by TBI + HS polytrauma improved neurological deficits and anxiety levels assessed one day post‐injury compared to rats receiving vehicle treatment. These neurobehavioral improvements with EF‐24 treatment were similar to improvements in injured rats that received blood transfusion treatment following polytrauma. In conclusion, EF‐24 is a promising pharmacotherapy for polytrauma injuries, similar in efficacy to a blood transfusion and could potentially be used as an alternative in the absence of blood transfusions (e.g. battlefield). Altogether, these findings make it worthy to further characterize EF‐24 efficacy on polytrauma‐induced long‐term neurobehavioral and biochemical deficits. This work was supported by Department of the Army ‐ Prolonged Field Care Research Award #W81XWH‐16‐DMRDP‐CCCRP‐PFCRA to Vibhudutta Awasthi.
Keywords: traumatic brain injury, hemorrhagic shock, polytrauma, neurological deficit, anxiety, pharmacotherapy
UNDERSTANDING THE CROSS‐SECTIONAL AND LONGITUDINAL RELATIONSHIPS PREDICTING SUICIDAL ENDORSEMENT FOLLOWING TRAUMATIC BRAIN INJURY
1University of Pittsburgh, Biostatistics, Pittsburgh, USA
2University of Pittsburgh, PM&R, Pittsburgh, USA
3University of Pittsburgh, Neuroscience, Pittsburgh, USA
4University of Pittsburgh, Safar Center, Pittsburgh, USA
5University of Texas‐Southwestern, PM&R, Dallas, USA
6Mount Sinai Health System, Rehabilitation Medicine, New York, USA
7NYU Rusk Rehabiitation, Psychology, New York, USA
8UAB Spain Rehabilitation, PM&R, Birmingham, USA
9University of Washington, Psychiatry, Seattle, USA
10University of Pittsburgh, Surgery, Pittsburgh, USA
Traumatic brain injury (TBI) is associated with high rates of unemployment and substance abuse (SA), which may impact mood disorders and associated suicidal endorsement (SE). The goal of this study was to assess temporal relationships of demographic and clinical factors influencing employment, SA, and depression, and their collective impact on SE. We applied logistic regressions and cross‐lagged structural equation models (CLSEM) on a uniquely merged database of 2,813 individuals with moderate‐to‐severe TBI, enrolled in both the National Trauma Data Bank and Traumatic Brain Injury Model Systems National Database, aged 18‐59, with data at years‐1 or −2 post‐injury. The data showed a satisfactory fit to our hypothesis (comparative fit index, CFI = 0.986). In the CLSEM, year‐1 unemployment (p < 0.001) and SA (p = 0.002) were associated with higher likelihood of year‐1 depression. Depression was associated with concurrent SE at years‐1 (p < 0.001) and −2 (p = 0.033). Older adults (p = 0.027) and women (p = 0.010) had a greater likelihood of year‐1 depression. Year‐1 SE was associated with a greater likelihood of year‐2 SE (p = 0.050). Lastly, higher ECI remained independently associated with a greater likelihood of year‐1 SE (p = 0.015) beyond the unique pathway to SE through interrelationships between employment, SA, and depression. This novel approach identifies the patients at risk and reinforces the need for early interventions. Support: UPP‐Foundation, NIH R21 HD 089075‐01, NIDILRR 90DP0041 and NIH Center for Large Data Research and Data Sharing in Rehabilitation NIH P2C HD065702
Keywords: employment, substance abuse, depression, suicide, traumatic brain injury
THE INTERRELATIONSHIP OF POST‐TBI EMPLOYMENT AND SUBSTANCE ABUSE: A CROSS‐LAGGED STRUCTURAL EQUATION MODELING ANALYSIS
1University of Pittsburgh, PM&R, Pittsburgh, USA
2University of Pittsburgh, Biostatistics, Pittsburgh, USA
3University of Pittsburgh, Clinical and Translational Science Institute, Pittsburgh, USA
4University of Pittsburgh, Safar Center, Pittsburgh, USA
5University of Texas‐Southwestern, PM&R, Dallas, USA
6Mount Sinai Health System, Rehabilitation Medicine, New York, USA
7NYU Rusk Rehabiitation, Psychology, New York, USA
8UAB Spain Rehabilitation, PM&R, Birmingham, USA
9University of Washington, Psychiatry, Seattle, USA
10University of Pittsburgh, Surgery, Pittsburgh, USA
Substance abuse (SA) post‐TBI has been linked to mood disorders, cognitive impairments, and unemployment. The primary objective of this analysis was to characterize the interrelationship of employment and substance abuse (SA) following TBI using logistic regression and cross‐lagged structural equation models (CLSEM). Our work evaluated extra‐cranial injury (ECI) as a novel predictor of outcome post‐TBI. This analysis used a cohort of n = 2,890 individuals with moderate‐to‐severe TBI and probabilistically matched data from the National Trauma Databank (NTDB) and Traumatic Brain Injury Model Systems (TBIMS). ECI was measured using injury severity score (ISS) from NTDB data, while employment and SA were taken from the TBIMS. Regression and CLSEM analyses included employment and SA as outcomes; age, sex, and ISS were predictors, while controlling for relevant covariates. CLSEM analysis showed older age predicted lower likelihood of employment and male sex predicted higher likelihood of SA post‐injury. ECI uniquely predicted a reduced likelihood of employment (p = 0.027) and SA (p = 0.050) at year‐1.. Lastly, post‐injury employment at year‐1 predicted an increased likelihood for SA at year‐2 (p = 0.028). Our analyses identified unique trauma, employment and substance use predictors of long‐term outcome, highlighting the need to consider complex temporal interrelationships post‐TBI, and suggest the need for more research to identify causal pathways to minimize SA and facilitate successful employment outcomes.
Keywords: substance abuse, employment, brain injury, polytrauma
MAYO‐PORTLAND ADAPTABILITY INDEX AND ASSOCIATIONS WITH HEADACHE TRAJECTORY AFTER TRAUMATIC BRAIN INJURY
1University of Pittsburgh, PM&R, Pittsburgh, USA
2Mount Sinai, Icahn School of Medicine, New York, USA
3Safar Center for Resuscitation Research, University of Pittsburgh, Pittsburgh, USA
4Clinical and Translational Science Institute, University of Pittsburgh, Pittsburgh, USA
Traumatic brain injury (TBI) is associated with persistent functional and clinical impairments after rehabilitation care. The International Classification of Functioning, Disability and Health (ICF) is a framework for organizing information on functioning and disability and is composed of five components of disability. The Mayo‐Portland Adaptability Index‐4 (MPAI) was developed to assess global outcomes by capturing a range of problems that ensue following TBI, including physical, cognitive, emotional, behavioral, and social complications. The MPAI has three subscales: ability, adjustment, and participation to assess disability in common areas of reintegration into society after TBI. Headaches are a cardinal physical symptom after TBI that can persist through the first‐year post‐injury and are associated other cumulative comorbidities. Thus, we aimed to map MPAI components onto the ICF framework, identify headache phenotypes, and determine how these phenotypes are associated with global disability as measured by the MPAI. We used monthly questionnaires to create temporal headache trajectories in a prospective cohort of adults with moderate‐to‐severe TBI (n = 79). We observed relationships between trajectories and overall MPAI standardized scores and subscales at 12‐months post‐injury. We observed three distinct headache trajectories: low (n = 21), resolve (n = 23), and chronic (n = 35). Individuals in the chronic group had worse scores for abilities, adjustment, participation, and overall scores compared to the low group (p < 0.10 all comparisons). Individuals in the resolve group also had worse participation scores compared to the low group (p = 0.01). Finally, the chronic group had worse adjustment scores than the resolve group (p = 0.05). We observed the MPAI overall score, and ability, adjustment, and participation subscales are associated with temporal headache profiles. Taken together, the presence of headache symptoms and trajectories for the first‐year post‐injury contribute to the cumulative disability burden following TBI that limits recovery and community integration following rehabilitation care.
Support: NIDILRR‐90DP0041.
Keywords: Mayo‐Portland Adaptability Index, ICF framework, headache
COMMUNITY‐BASED MEASUREMENT OF NEUROBEHAVIORAL SYMPTOMS AFTER TRAUMATIC BRAIN INJURY: DIFFERENCES BY INJURY SEVERITY AND GENDER
University of Texas Southwestern Medical Center, Physical Medicine and Rehabilitation, Dallas, USA
Keywords: Measurement, Brain Injury, Fatigue, Gender
FUNCTIONAL STATUS EXAMINATION VERSUS GOSE AS OUTCOME MEASURES IN TRAUMATIC BRAIN INJURIES: HOW DO THEY COMPARE
1University of Washington, Neurological Surgery & Rehab, Seattle, USA
2UCSF, Neurosurgery & Radiology, San Francisco, USA
3Medical College of Wisconsin, Neurosurgeryy & Neurology, Milwaukee, USA
Outcome measures are essential components of natural history studies of recovery and treatment effects following traumatic brain injury (TBI). The Glasgow Outcome Scale (GOS) and its revised version, the Glasgow Outcome Scale Extended (GOSE), are well accepted and widely used for both observational and intervention studies, but there are concerns about their psychometric properties and aptness as outcome measures for TBI. The present study compares the Functional Status Examination (FSE) with the GOSE to assess outcome following TBI in a sample of 533 participants with TBI from the Magnesium Sulfate study and the Transforming Research and Clinical Knowledge in Traumatic Brain Injury (TRACK‐TBI) study by evaluating the sensitivity of each measure to severity of brain injury and recovery of function over time. The results indicate that both measures are strongly correlated with TBI severity. At 3 months the correlation strengths between injury severity and each outcome measure do not differ (p = .92 for Glasgow Coma Scale (GCS), p = .14 for CT abnormalities) but at 6 months, the FSE is more strongly related to TBI severity indices than is the GOSE (p = .038 for GCS, p = .010 for CT abnormalities). In addition, the FSE generally shows significantly more improvement over time than the GOSE (p < .001). Detailed, structured administration rules and a wider score range of the FSE likely yields more sensitive and precise assessment of functional level than the GOSE. The FSE may be a valuable alternative to the GOSE for assessing functional outcome after TBI. This study was supported by the following grants: W81XWH‐14‐2‐0176, R01 NS1963, U01NS086090.
Keywords: Traumatic Brain Injury, Outcome assessment, Psychosocial outcome, Quality of life, Functional outcome
A PRELIMINARY DESCRIPTION OF THE RELATIONSHIPS AMONG DOPAMINE GENETICS, DEPRESSION, AND NEUROBEHAVIORAL SYMPTOMS IN CHRONIC TBI
1UT Southwestern Medical Center, Physical Medicine & Rehabilitation, Dallas, USA
2University of Pittsburgh, Physical Medicine & Rehabilitation, Pittsburgh, USA
3University of Pittsburgh, School of Nursing, Pittsburgh, USA
Keywords: traumatic brain injury, assessment, functional outcomes, fatigue
OPIOID EXPOSURE FOLLOWING TRAUMATIC BRAIN INJURY EXACERBATES BEHAVIORAL AND NEUROINFLAMMATORY OUTCOMES
1Wayne State University, Neurosurgery, Detroit, USA
2John D Dingell VAMC, Detroit, USA
3Wayne State University, Psychiatry and Behavioral Neuroscience, Detroit, USA
Traumatic brain injury (TBI) is linked with higher‐risk opioid use, which may result from post‐TBI opioid treatment. Both TBI and the opioid, morphine, induce reactive oxygen species (ROS) and glial‐mediated inflammation. Considering this, we hypothesized that post‐TBI morphine exposure increases opioid responding after injury by synergistically enhancing ROS and glial activation. C57Bl/6 mice (8‐10 weeks old) received a closed‐skull impact or sham surgery. Thirty days later, morphine reward responding was assessed using conditioned place preference (CPP) and two‐bottle choice drinking. Compared to sham, TBI mice displayed a significant 1.5‐fold higher preference for the morphine‐paired environment in CPP. Regarding morphine consumption, both sham and TBI mice displayed a marked preference (∼80%) for morphine intake when paired against a quinine tastant control. However, only TBI mice continued to show a morphine preference (∼70%) when measured against its vehicle (0.2% sucrose solution, no quinine), a response that was significantly greater than that of sham controls (∼30% preference) under these conditions. To assess early changes in oxidative generation, tissue ROS was measured from TBI and sham mice treated with morphine or saline for 7 days post‐injury using a fluorometric assay. While TBI‐saline mice exhibited increased ROS levels compared to respective sham controls, ROS accumulation was significantly greater in the TBI‐morphine cohort relative to all other groups. Our data also support the hypothesized exaggerated glial recruitment in TBI‐morphine mice, with reward‐related cortical areas showing a markedly enhanced Iba‐1 expression (microglial marker) in tissue from TBI‐morphine mice undergoing CPP compared to all other injury/treatment groups. Together, our data model heightened preference to morphine post‐TBI and suggest alterations in oxidative and inflammatory mediators may underlie this vulnerability. This work was supported by the resources and facilities of the John D. Dingell VAMC.
Keywords: opioids, morphine, conditioned place preference, voluntary intake, mice, oxidative stress
FRONTAL TRAUMATIC BRAIN INJURY IMPAIRS EFFORT‐BASED DECISION MAKING IN RATS
West Virginia University, Morgantown, USA
In clinical populations, traumatic brain injury (TBI) is comorbid with various psychiatric conditions such as depression. Unpublished data from our lab indicates that more sensitive measures are needed to effectively model depressive‐like behavior following severe TBI in rodents. The objective of this study was to evaluate subtle, chronic, depressive‐like symptoms following TBI in rats using the effort discounting task (EDT). The EDT models effort‐based decision making, or the degree of motivation to expend effort for a large reinforcer. In the study, 23 male Long‐Evans rats were trained on the EDT. During the EDT, rats were presented with two levers, one of which delivered a large reinforcer (3 sucrose pellets), and the other delivered a small reinforcer (1 sucrose pellet). Each session consisted of four blocks of trials. The small lever delivered pellets on a fixed‐ratio (FR) 1 schedule throughout each block (1 pellet for every 1 press). The large lever had an increasing effort requirement across blocks, beginning with FR2 and increasing to FR5, FR10, and ending with FR20 (3 pellets for every 2, 5, 10, or 20 presses). Rats were able to choose freely between the large and small levers. After reaching stability, rats were either given a severe bilateral frontal TBI using controlled cortical impact (AP/ML/DV +3.0/0.0/‐2.5 @ 3 m/s) or sham injuries. TBI animals decreased preference for the large lever across all four effort requirements. Deficits never recovered to sham levels, but some recovery was observed at 5‐7 weeks post‐injury on all effort requirements. At 8 weeks post‐injury, acute challenges of the DAT/NET antagonist Buproprion were administered. Bupropion treatment was ineffective at restoring TBI‐induced behavioral deficits on the EDT. In conclusion, the EDT appeared to be an effective task for capturing subtle, chronic, depressive‐like behavior that occurs following TBI. Tasks involving a choice between multiple options may be an appropriate avenue for modeling TBI‐induced depression. However, treatments for TBI‐induced depression require further assessment.
Keywords: Traumatic Brain Injury, Operant Behavior, Effort Discounting, Drug Challenge, Animal model
UNILATERAL PARIETAL TRAUMATIC BRAIN INJURY INCREASES RISKY DECISIONS ON A RAT GAMBLING TASK
1West Virginia University, Psychology, Morgantown, USA
2West Virginia University, Neuroscience, Morgantown, USA
The development of psychiatric‐like symptoms, including deficits in decision‐making are relatively common in patients post‐TBI. Prior work has shown that severe bilateral frontal TBI reduces optimal decision‐making on a rat gambling task (RGT), which is used to assess risk‐taking in rodents. To determine if these effects were specific to frontal lobe damage or more reflective of general TBI deficits, the current study evaluated the effects of unilateral parietal TBI on RGT acquisition. Rats were pair‐matched for rotarod baseline performance, and then assigned to sham or TBI groups. Craniotomies were performed for sham and TBI animals centered at AP +2.4mm, ML +2.4mm from bregma and unilateral parietal injuries were delivered to TBI animals using controlled cortical impact (CCI; −2.5 DV @ 3 m/s). Following a 7‐day recovery period, motoric effects were assessed for three additional sessions on the rotarod. All rats were then trained on the RGT. During the RGT, choice occurs between four reinforcer/punisher options, two of which are considered relatively “safe” while the alternatives are considered “risky.” Sugar pellets earned can be maximized during this procedure if choice is for the “safe” options exclusively. Behavior was tested daily for 30 minutes until reaching stability (∼8 weeks) and then euthanized. Injured animals demonstrated deficits in motor function as well as increased risk‐taking during the RGT as compared to sham animals. These deficits became more pronounced and endured through the entire eight‐week recovery period. Such results are similar to previous work showing deficits in risk‐based decision‐making following bilateral frontal TBI via CCI. However, the current data suggest that factors other than frontal tissue damage, such as alterations to the mesocortical dopamine pathway, may be involved in mediating these impairments. This work underscores the importance of assessing executive function following a variety of methods of TBI.
Keywords: unilateral, operant behavior, risk, rotarod
B03 Blood Brain Barrier
LESION SEVERITY AND VASCULAR INTEGRITY AFTER TRAUMATIC BRAIN INJURY IN PLAU/PLAUR‐DEFICIENT MICE
A. I. Virtanen Institute for Molecular Sciences, Kuopio, Finland
The expression of urokinase‐type plasminogen activator receptor (uPAR) and its ligand urokinase‐type plasminogen activator (uPA) are elevated after ischemic brain damage in animal models and humans. Deficiency in uPAR is associated with increased lesion size and impaired vascularization after brain insults. We investigated if a double‐deficiency of genes encoding uPA (Plau) and uPAR (Plaur) influence the cortical lesion size or the vascular integrity after experimental traumatic brain injury (TBI). TBI was induced in wild‐type (Wt) and Plau/Plaur double knockout (dKO) mice with lateral fluid‐percussion injury (FPI) –induced TBI (1.8 ± 0.1 atm). Severity of somato‐motor deficits were assessed with neuroscore at day (d)2, d4, d7 and d14 post‐injury. Mice were killed at d4 or d30 post‐TBI, and brains were processed for histology to quantify lesion size, to confirm uPAR colocalization with platelet‐derived growth factor receptor β (PDGFRβ), and to assess the number of perilesional PDGFRβ+ pericytes and blood vessels in different genotypes. Somato‐motor deficiency or recovery did not differ between the genotypes. The area of the cortical lesion did not differ between the genotypes at d4 (Wt 10.3 ± 0.6 mm2 vs. dKO 10 ± 1.4 mm2, p > 0.05) or at d30 (Wt 8.3 ± 1.5 mm2 vs. dKO 8.6 ± 1.1 mm2, p > 0.05) post‐TBI. The total number of perilesional PDGFRβ+ pericytes was higher at d4 than d30 post‐TBI in both Wt (387 ± 63 vs. 68 ± 19, p < 0.01) and dKO mice (417 ± 66 vs. 102 ± 36, p < 0.05). No genotype effect was found on total number of PDGFRβ+ pericytes at d4 or d30 post‐injury (p > 0.05). Furthermore, there was no difference between Wt and dKO mice in pericyte subpopulations (reactive vs. structural) at d4 (Wt 1:3, dKO 1:5) or d30 (Wt 1:7, dKO 1:5) post‐TBI. Confocal imaging confirmed the colocalization of uPAR in PDGFRβ+ pericytes in Wt mice. Our data demonstrates that Plau/Plaur‐deficiency has no effect on somato‐motor recovery, cortical lesion size or vascular changes after lateral FPI in mice.
Keywords: double knockout, lateral fluid‐percussion injury, pericyte, platelet‐derived growth factor receptor β
IMAGING BLOOD‐BRAIN BARRIER DISRUPTION BY DCE‐MRI AND LA‐ICP‐MS
1Boston University School of Medicine, Department of Radiology, Boston, USA
2Boston University School of Medicine, Molecular Aging & Development Laboratory, Boston, USA
3Boston University Photonics Center, Boston, USA
4Boston University College of Engineering, Boston, USA
5Zlotowski Center for Neuroscience, Ben‐Gurion University of the Negev, Departments of Brain & Cognitive Sciences, Physiology & Cell Biology, Beer‐Sheva, Israel
6Dalhousie University, Department of Medical Neuroscience and the Brain Repair Center, Faculty of Medicine, Halifax, Canada
Traumatic brain injury (TBI) is associated with significant secondary morbidity, including increased risk of late‐life cognitive impairment and age‐related neurodegenerative diseases. In this study, we evaluated dynamic contrast‐enhanced MRI (DCE‐MRI) with gadofosveset trisodium (a gadolinium‐based contrast agent that binds serum albumin) to detect and track blood‐brain barrier (BBB) dysfunction in mice after closed‐head impact injury. We used laser ablation inductively coupled plasma mass spectrometry (LA‐ICP‐MS) to map spatial distribution of Gd in mouse brains harvested 2 weeks post‐injury to confirm that the detected DCE‐MRI abnormalities represented true BBB permeability dysfunction. Gd maps of brains obtained from impact‐injured mice revealed enhanced Gd accumulation that colocalized with T1‐weighted hyperintensities and BBB disruption detected by DCE‐MRI. Our results provide “proof of concept” feasibility validation of DCE‐MRI for diagnostic evaluation of BBB dysfunction in the acute‐subacute period after closed‐head impact injury. We also investigated spatial distribution of gadolinium deposition in cerebral cortex in humans with and without history of traumatic brain injury after repeated exposure to intravenous Gd‐containing contrast agents. Non‐homogeneous gadolinium retention was detected by LA‐ICP‐MS imaging in cerebral cortex, pia mater, and pial‐ensheathed leptomeningeal blood vessels from human subjects with normal renal function and history of traumatic brain injury. Our results provide unequivocal evidence that in vivo DCE‐MRI and ex vivo LA‐ICP‐MS enable anatomical localization and quantitation of non‐hemorrhagic BBB disruption post‐injury.
Acknowledgment: BU ADC P30AG013846
Keywords: Traumatic Brain Injury, DCE‐MRI, LA‐ICP‐MS, Gadolinium‐Based Contrast Agents, Mouse Model
ALLOPREGNANOLONE ATTENUATES BLOOD‐BRAIN BARRIER DYSFUNCTION FOLLOWING TRANSIENT ISCHEMIA IN STRESSED MALE RATS
Emory University, Emerrgency Medicine, Atlanta, USA
Dysfunction of the BBB complicates a number of neurologic diseases including stroke. It has been shown that various kinds of stress in rodents compromises blood brain barrier (BBB) function. We and others have shown that allopregnanolone (ALLO), a neuroactive metabolite of progesterone, is neuroprotective and attenuates BBB disruption after stroke, but it is not known whether it will be as effective under a comorbid condition of chronic stress. Changes in ALLO levels have been detected in stress and stress‐related disorders including anxiety and depression. Brexanolone, an analogue of ALLO, was recently approved by the FDA for the treatment of postpartum depression. The present study examines the effects of ALLO on BBB integrity after exposure to stress followed by transient cerebral ischemia. Adult male Wistar rats were exposed to social defeat stress for eight consecutive days and then subjected to either sham surgery or 90 minutes of middle cerebral artery occlusion (tMCAO). ALLO (8 mg/kg) and/or vehicle (22.5% 2‐hydroxypropyl‐β‐cyclodextrin) were administered intraperitoneally 5 min before reperfusion, and then subcutaneously at 6, 24 and 48 hours. At 72h post‐stroke, the rats were killed and brains were evaluated for infarct size, BBB permeability. We examined the expression of immunoglobulin (IgG) and alteration of tight junction (TJ) and adherence junction (AJ) proteins as markers of BBB disruption. Significantly larger infarct volume was observed in the stress+tMCAO group compared to the unstressed tMCAO group, and treatment with ALLO significantly attenuated infarct volume in both tMCAO groups. IgG extravasation after tMCAO, indicating more severe BBB injury, was significantly higher in the Stress+tMCAO than the tMCAO‐alone rats. Stressed animals with ischemic injury showed significantly reduced expression of TJ (occludin and ZO‐1) and AJ (β‐catenin) proteins compared to the unstressed tMCAO group. Treatment with ALLO attenuated BBB disruption by preventing the degradation of occludin, ZO‐1 and β catenin. In conclusion, ALLO can reduce BBB disruption in chronically stressed rats following stroke. Our findings suggest that ALLO holds potential for clinical testing in cerebral ischemic stroke where high stress may be a contributing factor.
Keywords: Ischemia, Blood brain barrier, Stress, Tighr junction proteins
NRF2 PROTECTS THE BRAIN FROM TRANSMIGRATION OF BLOOD CELLS BY DOWN‐REGULATING ICAM‐1 AFTER TRAUMATIC BRAIN INJURY
Laboratory of CNS Injury and Molecular Therapy, JFK Neuroscience Institute, Hackensack Meridian Health JFK Medical Center, Edison, NJ, USA
Traumatic brain injury (TBI) facilitates the transmigration of inflammatory blood cells into the brain, an important mechanism underlying neuroinflammation. This study investigated the neuroprotective role of Nuclear factor erythroid 2‐related factor 2 (Nrf2) in controlling transmigration of monocytes to the brain by down‐regulating intercellular adhesion molecular‐1 (ICAM‐1) after TBI. Nrf2, a key transcription factor, is an endogenous defense mechanism present within cells that play a crucial role in cytoprotection against inflammation. Using human brain microvascular endothelial cells (hBMVECs), and wild‐type Nrf2+/+ and ICAM+/+, and Nrf2−/− and ICAM−/− deficient mice, we demonstrated the regulatory role of Nrf2 in transmigration of monocytes to the brain after TBI. hBMVECs were subjected to 2‐psi stretch‐injury, and after 24 hours, the cells were prepared for immunofluorescence, western blotting, permeability assay, transmigration study, Chromatin Immunoprecipitation qPCR (ChIP qPCR), and ELISA. For transmigration study, the human monocytes were labeled with Calcein‐AM and then added to inserts having tight hBMVECs monolayer and analyzed migrated fluorescent cells by a plate reader. Similarly, FITC Dextran‐4 was used for analyzing permeability assay. For in vivo transmigration study, we removed bone marrow from femur bone and cultured mouse monocytes. After a week, we labeled these cells with Calcein‐AM and infused through an exposed right carotid artery of the mouse and identified transmigrated cells in the brain. To validate this, we separated bone marrow from a GFP mouse, cultured monocytes, infused through the carotid artery, and identified these GFP cells using anti‐GFP antibody by immunofluorescence. ChIP qPCR was performed in vitro and in vivo using anti‐p‐Nrf2 antibody and the antioxidant genes such as HO‐1, Gpx‐1, and GSTm‐1, NQO1 were analyzed by qPCR. Our results show that Nrf2 downregulates the expression level of ICAM‐1 and reduces BBB permeability and transmigration of blood cells. Nrf2−/− mice exacerbate BBB dysfunction, permeability, and transmigration.
Keywords: Traumatic brain injury, Blood‐brain barrier, Nrf2 transcription factor, Transmigration of blood cells, ICAM‐1, Neuroprotection
DEVELOPMENTAL REGULATION OF MATRIX METALLOPROTEINASE‐9 MAY BLUNT THE SPREAD OF DAMAGE IN A SEVERE MODEL OF TBI
1Massachusetts General Hospital, Harvard Medical School, Neurosurgery, Boston, USA
2Massachusetts General Hospital, Harvard Medical School, Pediatric Critical Care Medicine, Boston, USA
Unilateral hemispheric hypodensity (HH) is a radiological pattern associated with abusive head trauma where holo‐hemispheric damage underlies the unilateral subdural hematoma (SDH). HH pathophysiology and the effect of age remain poorly understood. HH is more often bilateral in infants and unilateral in toddlers. In our model of unilateral HH, piglets receive unilateral injuries: mass effect, cortical impact, SDH, and induced seizures; and global insults: apnea and hypoventilation. We hypothesized that matrix metalloproteinase‐9 (MMP‐9) is increased and the blood brain barrier (BBB) is disrupted in regions of damage and are developmentally regulated. “Infant” (one‐week old) and “toddler” (one‐month old) piglets received HH model injuries or sham surgery. At 24 hours post‐injury, the pattern of MMP‐9 upregulation and BBB disruption paralleled the pattern of damage in “toddlers” with a unilateral pattern, but MMP‐9, BBB disruption, and damage were lower and bilateral in “infants”. In sections with over 30% of hemispheric damage that was equivalent among ages, “toddlers” had a greater amount of MMP‐9 upregulation and BBB disruption than “infants”. Pro‐MMP‐9 increased at 1‐4h post‐injury (P < 0.05) and returned to baseline levels by 24h post‐injury (P < 0.05) in both ages. However, active‐MMP‐9 was greater in “toddlers” vs “infants” at 1‐4h post‐injury (P < 0.05) and remained elevated at 24h post‐injury in “toddlers” (P < 0.0001), but not “infants”. In conclusion, “infants” had a blunted increase in MMP‐9, perhaps via regulation of the conversion of pro‐ to active‐MMP‐9 and had less BBB disruption, while MMP‐9 continued to increase in “toddlers” potentially allowing continued spread of BBB disruption and damage. MMP‐9 may be a therapeutic target for reducing tissue damage from severe brain injury.
Keywords: Matrix Metalloproteinase‐9, Traumatic Brain Injury
TAU PROCESSING BY MURAL CELLS IN TRAUMATIC BRAIN INJURY
1Roskamp Institute, Sarasota, USA
2Open University, Milton Keynes, United Kingdom
Keywords: Tau, Mural Cell
DYSFUNCTION OF BLOOD BRAIN BARRIER IN CONCUSSIVE HEAD TRAUMA
1Stanford University, Biomechanical Engineering, Palo Alto, USA
2Trinity College Dublin, Smurfit Institute of Genetics, Dublin 2, Ireland
3Institute of Technology Tallaght, Tallaght, Ireland
4Stanford University, Mechanical Engineering, Palo Alto, USA
Diagnosis of mTBI is currently only based on signs and symptoms because it cannot be seen in CT and conventional MRI scans. Recently, using Dynamic Contrast Enhanced (DCE) MRI, the dysfunction of the Blood Brain Barrier (BBB) is found in many contact sports like rugby and mixed martial arts (MMA). And in previous studies with pig and mouse brain models, axonal pathology was found to be associated with BBB disruption, which implies that BBB can serve as a biological sensor for brain deformation and injury. In this study, 4 MMA fighters were injected with a weight‐based bolus of Gadolinium as contrast and scanned by DCE‐MRI before and after fights. The permeability of BBB was measured by the slope of density contrast in each voxel over time, and the fighters were instrumented with mouthguard developed by the Camarillo lab at Stanford. Accelerometers and gyroscopes were installed in the mouthguard to record the head kinematics. Then, the skull movements were applied to a finite element head model to calculate the brain deformation. The volume percentage of BBB dysfunction V is found to be in good linear relationship with the number of hits N as N = a 1·V + b 1 (a 1 = 66.4+‐45.2, b 1 = 1.48+‐7.11, R 2 = 0.95), and the average slope of contrast K is found to have a positive correlation with the peak deformation S during the match as S = a 2·K + b 2 (a 2 = 4.6+‐10.6, b 1 = 0.00+‐7.77, R 2 = 0.64).
Keywords: BBB Dysfunction, mTBI, Concussion, Mouthguard
APPLICATION OF DELAYED‐CONTRAST MRI FOR DEPICTING SUBTLE BLOOD‐BRAIN‐BARRIER DISRUPTION IN TBI
1Sheba, Joseph Sagol Neuroscience Center, Ramat‐Gan, Israel
2Sheba, Advanced Technology Center, Ramat‐Gan, Israel
3HUJI, Institute for Drug research, Jerusalem, Israel
4OAC, Faculty of Health Profession, Kiryat‐Ono, Israel
Keywords: Gliovascular
ACTIVATIONAL STATE OF NEUTROPHILS IS A DETERMINANT OF ACUTE AND LONG‐TERM DYSFUNCTION AFTER INJURY TO THE DEVELOPING BRAIN
1UCSF, Laboratory Medicine, San Francisco, USA
2The University of Texas at Austin, Neurology and Pschology, Austin, USA
While traumatic brain injury (TBI) is the leading cause of death and disability in children, we have yet to identify those pathogenic events that determine extent of recovery. Neutrophils are best known as “first responders” to sites of infection and trauma where they become fully activated, killing pathogens via proteases that are released during degranulation. However, this activational state may generate toxicity in the developing brain after TBI, where there is increased vulnerability due, in part, to inadequate antioxidant reserves. Neutrophil degranulation is triggered via a downstream signaling pathway that is dependent on spleen tyrosine kinase (SYK). To test the hypothesis that the activational state of neutrophils is a determinant of early tissue disruption and long‐term recovery, we compared young, brain‐injured conditional knockouts of SYK (sykf/fMRP8‐cre +) to congenic littermates (sykf/f ). Flow cytometry revealed the extended recruitment of distinct leukocyte subsets including Ly6Ghi/Ly6C‐ and Ly6Ghi/Ly6Cint, over the first several weeks post injury. These infiltrating neutrophils do not express CD206 or Arginase 1, suggesting that infiltrating neutrophils are of N1 type. While the magnitude of recruitment did not differ across genotypes, blood brain barrier disruption to both high and low molecular weight dextrans, expression of claudin 5, generation of reactive oxygen species, and neuronal loss were significantly reduced in the acutely injured brains of sykf/fMRP8‐cre + mice. At adulthood, brain‐injured sykf/fMRP8‐cre + mice showed robust improvements in task memory, and short and long‐term spatial memory retention. Our results establish the first mechanistic link between the activational state of neutrophils and long‐term cognitive recovery after traumatic injury to the developing brain and highlights a novel therapeutic target that could be further developed for the brain‐injured child. This work was supported by grant from NIH/NINDS 5R01NS077767‐05 (to L.J.N)
Keywords: Neutrophils, Traumatic brain injury, cognition, flow cytometry
CLINICAL TRANSLATION OF GROWTH FACTOR‐RELEASING BIOCELLULOSE BIOMATERIAL FOR NEURAL STEM CELL PROLIFERATION IN TBI
1University of Ottawa, Cellular and Molecular Medicine, Ottawa, Canada
2Ottawa Hospital Research Institute, Neurosciences, Ottawa, Canada
3University of British Columbia, Medicine, Vancouver, Canada
4University of Ottawa, Chemical and Biological Engineering, Ottawa, Canada
5Ottawa Hospital, Surgery, Ottawa, Canada
Current treatments cannot repair brain damage caused by traumatic brain injury (TBI). Improved neurological function in animal models has been shown with the application of epidermal growth factor (EGF) and fibroblast growth factors (FGF2) for neuroprotection and neural stem/progenitor cell (NSPCs) survival and proliferation. However, therapy translation to humans is limited by systemic side‐effects and life‐threatening intracranial pressure (ICP) increases associated with intraventricular infusion. To aid clinical translation, we have developed an EGF‐ and FGF2‐releasing biocellulose (BC) duraplasty material that can be used as a component of decompressive craniotomy (DC) which is a surgical remedy for increased ICP. The BC material would facilitate the targeted delivery of EGF and FGF2 to the edematous, injured brain. The efficacy of growth factor loaded BC material was assessed using in vitro neurosphere and differentiation assays along with in vivo biocompatibility testing in rodents. The loaded BC material stimulated NSPCs proliferation compared to the negative controls of serum‐free media (SFM) and nude BC with the number of neurospheres being 11.3 ± 1.3 for loaded BC, 0.6 ± 0.1 for SFM, and 0.6 ± 0.1 for nude BC (p < 0.01, n = 10 per group) over one‐week. The NSPCs from growth‐factor loaded BC treatment group were capable of differentiation into astrocytes, oligodendrocytes, and neurons. Lastly, we demonstrated using hematoxylin and eosin staining that the BC was a safe duraplasty that could be placed in rodents for 1 week and 4 weeks post‐decompression (n = 5 per group). We have developed a biocompatible BC that can deliver growth factors to promote the neuroprotection and proliferation of NSPCs. This BC implant may facilitate the clinically feasible translation of animal therapeutic strategies to humans.
Keywords: Duraplasty, Growth Factors, Biocellulose, Biomaterial, Rodent model, Neural stem and progenitor cells
NEUROVASCULAR EFFECTS OF SINGLE OR MULTIPLE MTBIS
1University of Texas Health Science Center, Neurobiology and Anatomy, Houston, USA
2University of Mississippi Medical Center, Neurobiology and Anatomical Sciences, Jackson, USA
Traumatic brain injury (TBI) has been shown to cause a disruption to neurovascular function in moderate to severe models, leading us to be interested in vascular pathology after single and repeat mild TBI. Adult male C57BL/6 mice received either a single mTBI, or 4 mTBIs spaced 24 hours apart. Brains were collected at 24h or 7d after the final injury for histology, and at 5d for protein analysis. One marker of vascular disruption is the presence of serum protein IgG in the tissue, indicating a disruption of the endothelial cells or the endothelial glycocalyx. Using histological methods, we found that at 24 hours following a single injury, IgG was associated with the luminal of the blood vessels. Coinciding with this was a profound loss of endothelial glycocalyx integrity determined using Lycopersicon esculentum (tomato lectin). However, while IgG labeling had returned to sham levels at 7 days, the glycocalyx had not yet recovered. Further, we investigated the effects of single vs. multiple mTBIs on expression of P‐glycoprotein (Pgp), a vascular efflux pump that is known to restrict CNS access of systemically‐administered therapeutics. While a single injury did not elicit an increase compared to sham, we observed a significant increase following multiple injuries. This suggests a sustained upregulation of Pgp and a possible induction of a state of chemotherapeutic resistance in the traumatized brain.
Keywords: preclinical, repeat injuries, multiple injuries, concussion
B04 Chronic Traumatic Encephalopathy
BILATERAL INTERNAL JUGULAR VEIN COMPRESSION MAY AMELIORATE TAU ACCUMULATION AND NEUROINFLAMMATION AFTER ROTATIONAL CLOSED HEAD IMP
Rebekah Mannix1,2, Nicholas Morriss1, Grace Conley1, Sara Ospina‐Mora1, Ashley Conley1, William Meehan1,2,3,
1Boston Children's Hospital, Emergency Medicine, Boston, USA
2Harvard Medical School, Boston, USA
3Boston Children's Hospital, Orthopedics, Boston, USA
4University of Cincinnati, Pediatrics and Orthopaedic Surgery, Cincinnati, USA
5Cincinnati Children's Hospital Medical Center, The SPORT Center, Division of Sports Medicine, Cincinnati, USA
Keywords: Tau phosphorylation, mTBI, swine, inflammation
BOSTON UNIVERSITY CONCUSSION SCALE (BUCS)
1Boston University School of Medicine, Boston, USA
2Boston University College of Engineering, Boston, USA
3Boston University Alzheimer's Disease Center, CTE Program, Boston, USA
Concussion in humans is characterized by rapid onset and spontaneous resolution of a constellation of somatic, neuromotor, cognitive, and behavioral signs and symptoms precipitated by head injury with or without loss of consciousness. Neurological signs of acute concussion include confusion, altered mentation, slowed reaction time, motor weakness, impaired balance, incoordination, dystaxia, affect lability, and amnesia. Preclinical models of acute concussion have eluded development due to experimental requirements for anesthesia during injury. Recently, we showed that unanesthetized mice subjected to closed‐head impact injury induced with a novel momentum transfer device reliably triggered abrupt onset and rapid recovery of a concussion syndrome similar to that in humans (Tagge CA et al., Brain, 2018). We developed the Boston University Concussion Scale (BUCS‐1.0) as a multidimensional test battery for rapid, objective assessment of acute concussion in awake, unanesthetized mice. BUCS‐1.0 comprises three 30‐sec subtests (open‐field, inverted wire mesh, beam walk) scored on standardized metrics (0–5) that capture graded task‐specific deficits and summed as a composite score (BUCS range, 15–0). We conducted BUCS testing 2 min pre‐injury (baseline), 2 min post‐injury (post‐injury), after 3‐hr rest period (recovery). Most mice (166/203, 81.8%) exhibited mild neurological impairment (BUCS ≥10) after single impact. Fewer (32/203, 15.8%) showed moderate impairment (BUCS, 9–5). Severe impairment (BUCS ≤4) was rare (5/203, 2.5%). All mice recovered to baseline, typically in minutes and always by 3‐hrs post‐injury. In a revised format (BUCS‐2.0), we incorporated and validated a cognitive measure of spatial memory during the open‐field subtest. Surprisingly, we did not observe acute concussion in mice exposed to experimental blast matched for head kinematics. However, both injuries (impact, blast) triggered phosphorylated tau proteinopathy and allied pathologies associated with chronic traumatic encephalopathy (CTE). Our results indicate that neurotrauma, not concussion, triggers CTE. Funding: DoD TATRC W81XWH‐13‐1‐0263, Concussion Legacy Foundation, Anonymous Foundation.
Keywords: Concussion, Chronic Traumatic Encephalopathy, Animal Models, Impact Neurotrauma, Blast Neurotrauma, Traumatic Brain Injury
TARGETING SYNAPTIC PROCESSES PREVENTS THE COGNITIVE DYSFUNCTION INDUCED BY REPETITIVE HEAD IMPACT
Georgetown University, Neuroscience, Washington, USA
Keywords: Concussion, CTE, Synapse, TBI
TACKLING FOOTBALL'S INFLUENCE ON LIFELONG HEALTH AND DEMENTIA RISK
1University of Glasgow, Institute of Neuroscience and Psychology, Glasgow, UK
2University of Glasgow, Institute of Cardiovascular and Medical Sciences, Glasgow, UK
3Hampden Stadium, Hampden Sports Clinic, Glasgow, UK
4University of Glasgow, Institute of Health and Wellbeing, Glasgow, UK
5University of Pennsylvania, Department of Neurosurgery, Philadelphia, USA
6Queen Elizabeth University Hospital, Department of Neuropathology, Glasgow, UK
In the past decade, evidence has emerged suggesting a potential link between contact sport participation and risk of neurodegenerative disease (NDD), in particular, chronic traumatic encephalopathy (CTE). Nevertheless, despite widespread public concern, robust data to inform on actual risk of NDD in former athletes are lacking. While there is pressing need to gain greater understanding of NDD risks from contact sport participation, these must be read in context of wider lifelong health outcomes. Football's InfluencE on Lifelong health and Dementia risk (FIELD) is a retrospective cohort study accessing comprehensive, electronic medical and death records of NHS Scotland. All Scottish professional association footballers (soccer players) born between 01/01/1900 and 31/12/1976 (n = 9,670) were identified from the National Football Museum and professional football club archives. Players were each matched to 3 population controls and records interrogated for a range of outcomes. Pilot observations on a sample cohort, born between 1900 and 1930 (n = 504), demonstrates life expectancy in footballers from this era as 76.2 (±10.6) years, compared with a predicted life expectancy from population modelling of 64.4 (± 1.0) years; representing an average increase in actual versus predicted life expectancy of 11.8 (± 10.5) years (p < 0.001; paired t‐test). Interrogation of the data is now being pursued to address the primary aims of FIELD. These data demonstrate that participation in contact sport (soccer) at elite level is associated with increased life expectancy. As such, while studies focus on NDD risk in former athletes, these risks must be balanced against lifelong health outcomes from physical activity to generate appropriately informed, balanced risk assessments.
Keywords: Chronic Traumatic Encephalopathy, Public Health, Neurodegeneration, Sport
EARLY ADDRESS OF POST‐TRAUMATIC GLYMPHATIC INSUFFICIENCY REDUCES NEURONAL/GLIAL CELL DEATH AND TISSUE DAMAGES
1University of Rochester, Department of Neurosurgery, Rochester, USA
2University of Copenhagen, Center for Basic and Translational Neuroscience, Copenhagen, Denmark
Neuronal and glial cell death either by necrosis or through programmed cell death pathways are the most important features of traumatic brain injury (TBI) at anatomical scale. Necrosis is expected at the site of injury due to direct application of mechanical forces while programmed cell death is more prevalent within the peri‐lesion site as well as in the region far from the site of impact. Emerging evidences show that TBI disturbs the extracellular ionic balance and significantly increase the levels of excitatory neurotransmitters at the injury site, and simultaneously impairs peri‐vascular CSF circulatory pathway named as glymphatic system. We hypothesize that normalizing the CSF flow within the brain early after injury could reduce the TBI mediated damages, and down regulates tissue inflammation by flushing the excessive metabolites and waste products out of the brain parenchyma. In current series of experiments, cortical impact was induced in mice using hit and run model, mice were treated with saline or nor‐adrenergic receptor inhibitor cocktail immediately after the injury. Immunohistochemistry, glymphatic assays, cerebral edema measurements, and western blots were performed up to two weeks post‐TBI. Our findings suggest that early address of glymphatic impairment reduces cerebral edema, astrogliosis, and secondary tissue damages. Furthermore, terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) assay, caspase I, 3 and 7 immunostaining suggest a significant reduction in cell death within the peri‐lesion area in nor‐adrenergic receptor antagonist treated group. Together, these finding suggests glymphatic stimulation a future therapeutic approach to reduce cell death and tissue damages in traumatic brain injury field.
Acknowledgment: This work was supported by the Office of the Assistant Secretary of Defense for Health Affairs under the Peer Reviewed Alzheimer's Research Program through the Award No. W81XWH‐16‐1‐0555. Opinions, interpretations, conclusions, and recommendations are those of the author and are not necessarily endorsed by the Department of Defense.”
Keywords: Glymphatic, TBI, nor‐adrenergic inhibition, apoptosis
INTERACTION OF APOE4 ALLELES AND [18F]AV1451 PET TAU IMAGING IN FORMER PROFESSIONAL ATHLETES WITH MULTIPLE CONCUSSIONS
1UofT, IMS, Toronto, CA
2UofT, Tanz CRND, Toronto, CA
3UHN, Neurology, Toronto, CA
4Krembil, Canadian Concussion Centre, Toronto, CA
5UHN, Neuroradiology, Toronto, CA
6UofT, Rehabilitation Sciences, Toronto, CA
7UHN, Neurosurgery, Toronto, CA
8UofT, Surgery, Toronto, CA
9CAMH, PET Centre, Toronto, CA
10UofT, Medicine, Toronto, CA
Keywords: Positron emission tomography, Tau, APOE4, Apolipoprotein E
B05 Concussion / Mtbi
MOUSE MODEL OF CLOSED‐HEAD IMPACT CONCUSSION AND CHRONIC TRAUMATIC ENCEPHALOPATHY (CTE)
1Boston University, College of Engineering, Boston, USA
2Boston University, School of Medicine, Boston, USA
3Lawrence Livermore National Laboratory, Livermore, USA
4University of Oxford, Oxford, UK
The mechanisms by which head injury induces concussion and chronic sequelae are not known. We examined postmortem brains from young athletes after concussive head injury and found parenchymal contusion, myelinated axonopathy, microvasculopathy, neuroinflammation, neurodegeneration, and phosphorylated tauopathy consistent with early chronic traumatic encephalopathy (CTE), a progressive tau protein neurodegenerative disease. We developed a biofidelic mouse model of closed‐head impact concussion that induces traumatic head acceleration (without skull deformation), acute concussion, and mild traumatic brain injury (mTBI) in non‐anesthetized C57BL/6 mice. Head‐injured mice exhibited acute onset of contralateral limb weakness, impaired balance, locomotor abnormalities, and cognitive dysfunction that recapitulate acute concussion in humans. Neurological function rapidly returned to baseline, but CTE markers—focal blood brain barrier disruption, neuroinflammation, impaired axonal conduction and long‐term potentiation (LTP) of synaptic transmission, progressive phosphorylated tau proteinopathy—persisted, and for tauopathy progressed, long after concussion resolution. Kinematic analysis revealed traumatic head acceleration sufficient to induce concussion, TBI, and CTE neuropathology. Notably, the presence and severity of acute concussion (Boston University Concussion Scale) did not correlate with CTE markers or TBI sequelae. Moreover, concussion was observed after closed‐head impact injury but not after blast exposure with comparable head kinematics. Dynamic modeling revealed greater focal ipsilateral brain shear stress during impact compared to blast before onset of head motion. These results indicate that while acute concussion and chronic sequelae may be triggered by the same insult, the pathophysiological underpinnings of each engage distinct mechanisms, time domains, and consequences. Our results indicate that concussion per se is neither necessary nor sufficient to trigger acute brain injury or CTE. Funding: DoD TATRC W81XWH‐13‐1‐0263, Concussion Legacy Foundation, Anonymous Foundation.
Keywords: traumatic brain injury, chronic traumatic encephalopathy, tau protein, animal model, computational model
GAIT ANALYSIS OF MALE AND FEMALE RATS AFTER REPEATED MILD TRAUMATIC BRAIN INJURY
Georgia Institute of Technology, Atlanta, USA
Approximately 2 million traumatic brain injuries (TBIs) per year are diagnosed in the US, and 80% of those are classified as “mild” (mTBI). Sex, age, previous injury, and other factors may affect an individual's response to these injuries, but these variables are not typically investigated in preclinical studies. Therefore, an animal study that addresses the heterogeneity shown in human populations is a necessary tool. Gait analysis is a fast and reliable diagnostic tool to can be translated to humans. To this end, we examined the effects of repeated mTBI on male and female rats. In this study, 8 male and 8 female young adult Sprague‐Dawley rats were split into injury (n = 4 male, 4 female) and sham groups (n = 4 male, 4 female). Animals were anesthetized, placed on an EVA foam pad without head fixation, and given an mTBI using a controlled cortical impact device (5 m/s, 5mm head displacement). The animals were injured five times with a 24‐hour interval between impacts. The sexes showed no significant differences in injury state as determined by toe pinch and righting time. The animals were then tested on the Noldus CatWalk XT gait analysis system once a day for seven days following the final injury. The injured females were significantly different compared to sham animals in 14 of 45 variables analyzed, while the injured males were only significantly different than sham animals in 8 of the 45 variables. It should be noted that the females showed significance in the same measures for different paws more frequently than the males, which further supports the argument that there are distinct differences in the responses of males and females to injury. While the use of one sex in research can ensure reliable testing conditions, this practice fails to identify different injury responses in the untested sex. This study shows that male and female rats have different outcomes in gait to the same injury conditions. Supported by NIH R21NS091832
Keywords: Gait, CatWalk, Heterogeneity, Sex Differences
ACUTE DECREASES IN CEREBRAL BLOOD FLOW REFLECT CHANGES IN AKT SIGNALING AND ENDOTHELIAL NOS AFTER MILD REPETITIVE TRAUMATIC BRAIN
1Georgia Tech, Inst for Bioengineering and Bioscience/Mechanical Engineering, Atlanta, USA
2Emory University, Department of Biomedical Engineering, Atlanta, USA
Repetitive mTBIs sustained within a window of vulnerability can lead to cumulative severity/duration of cognitive impairments compared to a single mTBI. Using a weight‐drop closed head injury (CHI) model that features blunt impact of the intact skull/scalp followed by rotational head acceleration, we previously found that low cerebral blood flow (CBF) measured early post‐injury is an acute biomarker of poor cognitive outcome after rmTBI. Here, we explore molecular changes that may drive acute CBF changes after repetitive mTBI. Specifically, because endothelial nitric oxide synthase (eNOS) activity is a key driver of nitric oxide production and vasodilation, we hypothesized that eNOS and key regulators of eNOS activity, such as Akt, would be downregulated in mice with lower CBF after repetitive mTBI. To test this, cortical CBF was non‐invasively measured with Diffuse Correlation Spectroscopy in anesthetized animals at 4h after 3 CHI spaced once‐daily. After CBF assessment, the brain was collected and the left cortex was microdissected for analysis by Western Blot and Luminex multiplexed ELISA analysis of phospho‐proteins within the MAPK, PI3K/Akt, and NFκB pathways. N = 8/7 injured/sham C57B6 adult male mice were studied. No significant differences were observed in eNOS or phosphorylated Akt between groups. However, within the injured group, acute CBF significantly correlated with total eNOS (R = 0.80, p = 0.017) and trended towards significance with phosphorylated Akt (R = 0.61, p = 0.11) assessed from cortical tissue lysates. Given that eNOS activity is known to drive changes in CBF, and phospho‐Akt activates eNOS via phosphorylation at Ser1179, these data suggest that low CBF after repetitive mTBI may be driven by reduced eNOS activity. Our ongoing work is interrogating changes in eNOS phosphorylation together with activity of other NOS isoforms in an effort to fully elucidate mechanisms driving reduction of CBF after repetitive mTBI.
Keywords: eNOS, Akt, Nitric Oxide, Vascular tone
NON‐INVASIVE VAGAL NERVE STIMULATION REDUCES NEUROLOGICAL DYSFUNCTION AFTER CLOSED HEAD INJURY IN MICE
1Massachusetts General Hospital, Neuroscience center, Boston, USA
2Electrocore LLC, N/A, Basking Ridge, USA
Keywords: closed head injury, vagal nerve stimulation, mice, functional outcome, Prophylaxis
ELEVATED SERUM MICRORNA LEVELS CORRELATES WITH NEUROCOGNITIVE OUTCOMES AFTER SPORTS CONCUSSION
1Henry M Jackson Foundation/ Uniformed Services University, Bethesda, USA
2Uniformed Services University, Bethesda, USA
3Orlando Regional Medical Center, Orlando, USA
4Pennsylvania State University, Pittsburg, USA
5Northwestern University, Chicago, USA
6Penn State College of Medicine, Pittsburg, USA
7Univesity of Chicago, Chicago, USA
8Sandlake Imaging, Orlnado, USA
9Michigan State University, East Lansing, USA
10University of Nebraska, Lincoln, USA
11Purdue University, west Lafayette, USA
Sports‐related concussions are considered a major public health problem. It is estimated that (4‐9) % of players suffer concussive injuries every year. Concussion is largely a clinical diagnosis based on injury, neurologic examination and neuropsychological testing. Blood‐based biomarkers could complement the clinical evaluation and guide management decisions. Circulating miRNAs have been reported as biomarkers of several diseases due to their stability and ease of detection. Earlier, we have reported a panel of miRNAs as to detect mild to severe TBI. In this prospective study, we assessed the performance of a novel panel of serum microRNA (miRNA) biomarkers of indicators of concussion, sub‐concussive impacts, and neurocognitive function in NCAA collegiate football players. 30 non‐athlete control subjects and 23 male collegiate student football athletes participated in this study. Neurocognitive assessments and blood samples were taken within the week before the athletic season began and within the week after the last game and a pre‐selected panel of miRNA biomarkers was measured. Elevation of miRNAs was observed in all the athletes at the beginning of the season compared to control subjects. Athletes with the lowest standardized assesment score (SAC) at the beginning of the season had the highest level of miRNA expression. Increased miRNA expression were found to be associated with a declining neurocognitive function. The results of this study suggest that miRNAs are good indicators of sub‐concussive and concussive injuries and can be further explored for concussion biomarkers.
Keywords: Concussion, microRNA, Biomarker
TRANSIENT PERTURBATION IN NEURO‐OPHTHALMOLOGIC FUNCTION AFTER REPETITIVE SUBCONCUSSIVE HEAD IMPACTS: A RANDOMIZED CONTROLLED TRIAL
1Indiana University, Kinesiology, Bloomington, USA
2Indiana University, Psychological and Brain Sciences, Bloomington, USA
3Indiana University, Epidemiology and Biostatistics, Bloomington, USA
Keywords: subconcussive head impact, neuro‐ophthalmology, concussion, soccer
PRELIMINARY EVIDENCE‐BASED RECOMMENDATIONS FOR RETURN TO LEARN: A NOVEL PILOT STUDY TRACKING CONCUSSION RECOVERY IN COLLEGE STUDENTS
Indiana University Bloomington, Bloomington, USA
Keywords: Return to Learn, Return to School, Longitudinal, Evidence‐Based, Text Message
PEPTIDOMIC APPROACH TO IDENTIFY TAU BREAK DOWN PRODUCTS FROM IN VITRO, ANIMAL AND HUMAN BIO‐FLUID OF TRAUMATIC BRAIN INJURY MODELS
1Kuwait University, Department of Biological Sciences, Khaldiya, Kuwait
2University Of Florida, Department Of Chemistry, Gainesville, U.S.A.
Traumatic brain injury (TBI) is a multifaceted injury that generates an extensive range of medical complications. Proteolytic signaling cascades become activated within the cell following brain injury (e.g., calpain and caspase pathways), resulting in truncation of tau, and generating varying lengths of fragments (MW ∼400‐45,000 Da). Tau hyperphosphorylation and proteolysis plays a fundamental role in causing neurodegenerative damages as in AD, TBI, and CTE. Inhibiting a specific pathway that is involved in tau hyperphosphorylation and proteolysis can mitigate tauopathies‐associated neurotoxicity and improve functional outcomes for therapeutic approaches. This study utilized immunological (antibody‐based detection), and peptidomic approach to investigate tau proteolytic fragments (≤10 kDa), and pathological phosphorylation sites derived from in vitro, animal TBI models and human cerebrospinal fluid (hCSF) samples. From our immunoblotting analysis, we were able to identify tau fragments at 40 kDa, 24 kDa and 15 kDa (p‐value <0.05) following neurotoxic conditions and animal models of TBI. As for peptidomic analysis, samples were subjected to ultrafiltration (10 kDa molecular weight cut‐off value), and the filtrates were analyzed using nanoLC‐MS/MS. Novel calpain‐tau cleavage sites were identified (n = 3) including: G19↓L20, Q49↓T50, A89↓A90, Q124↓E125, and Thr720↓Ser721 following in calpain digestion. We also identified low molecular weight calpain‐mediated tau peptides including N‐terminal peptide, C‐terminal peptides, and in an in vitro and in vivo animal TBI models. As for hCSF samples, we were able to observe an overall increase in tau hyperphosphorylation with TBI subjects (p < 0.05) with different tau epitopes (e.g. Ser202 and Thr231). The N‐terminal peptide generated by calpain digestion was detected (n = 3) in CSF samples with the injury. Monitoring a subset of these targets generated from TBI and the accompanied bio‐fluid might provide biomarker utilities and can be applied as a potential “theragnostic” tool in augmenting the clinical trials for new TBI drug development.
Keywords: Tau proteolysis, Peptidomics, Tau break down products, Cerebrospinal fluid biomarkers, Tau calpain proteolysis
CIRCULATING MICRORNAS AS BIOMARKERS OF CONCUSSION IN AMATEUR AUSTRALIAN RULES FOOTBALLERS
1Monash University, Department of Neuroscience, Melbourne, Australia
2La Trobe University, Department of Physiology, Anatomy and Microbiology, Melbourne, Australia
3The University of Sydney, NHMRC Clinical Trials Centre, Sydney, Australia
Keywords: microRNA, blood biomarker, sports‐related concussion
TRANSCRANIAL DOPPLER ULTRASOUND PULSE MORPHOLOGY DIFFERENCES AFTER SPORTS‐RELATED CONCUSSION DURING VASOMOTOR REACTIVITY TESTING
Neural Analytics, Inc., Los Angeles, USA
Previous studies exploring the hemodynamic changes after a mild traumatic brain injury using breath‐hold induced hypercapnia from this group, found significant differences in pulsatile morphology early in the post‐injury period. In the pilot study presented here, the presence of similar pulse‐level alterations are explored using a CO2 gas‐challenge protocol. Ten subjects between the ages of 14 and 19, with sports‐related concussion (SRC) were compared to 27 in‐sport controls (ISC), and 34 out‐of‐sport controls (OHC), using 2MHZ Transcranial Doppler (TCD) Ultrasound of the middle cerebral arteries during vasomotor reactivity testing. After a 4‐minute baseline period of normal inspiration, there were two periods of 5% CO2 induced hypercapnia for 1‐minute followed by a 1‐minute recovery period of normal room air. In this analysis, the pulsatility index (PI), resistivity index (RI), and P2 ratio (P2R), were extracted from the challenge sections. Statistical comparisons were completed using the Mann‐Whitney rank test. Interestingly, during the first challenge section there was no significant difference in features between the SRC population and either control group. During the second challenge section however, the difference in mean RI was significant between both the ISC group, (RIISC: U = 104.0, nSRC = 10, nISC = 34, P = 0.03, CL = 0.69), and the OSC group, (RIOSC: U = 75.0, nSRC = 10, nOSC = 27, P = 0.02, CL = 0.72), over days 1‐2 post‐injury. In addition, the mean PI differences were significant between the OSC group (PIOSC: U = 78.0, nSRC = 10, nOSC = 27, P = 0.03, CL = 0.71). After the first 3‐days post‐injury, there were no significant differences observed. There were no significant differences found in P2R. In our previous studies employing breath‐holding induced hypercapnia, these pulse‐level features were only significantly different within the first 48‐hours. The results here suggest a similar mechanism as found with breath‐holding but that the CO2 method may provide higher sensitivity.
Keywords: Transcranial Doppler, Cerebral Hemodynamics, Vasomotor Reactivity
OCULAR MOTOR ABNORMALITIES AND SHORTENED TELOMERES IN COLLISION SPORT ATHLETES
Monash University, Department of Neuroscience, Melbourne, Australia
Mild brain injuries associated with collision sport participation have been linked to a range of neurological consequences, with evidence suggesting that these athletes are more vulnerable to developing neurological syndromes later in life. Consequently, there is a need to understand how potential neurological changes manifest and whether abnormalities are specific to concussion history or whether sub‐concussive impacts also contribute. With female participation in collision sports rising, there is also further need to determine whether changes manifest differently between sexes. This study investigated the neurological implications of collision sport participation in male (n = 72) and female (n = 28) amateur Australian rules footballers, with and without a history of concussion, in comparison to male (n = 29) and female (n = 21) non‐collision sport control athletes. Effects of collision sport participation was investigated in two ways: (1) ocular motor assessment, a demonstrated sensitive marker of brain and namely cognitive functioning in a range of collision sports; (2) telomere length, found to be reduced in rodents given mild brain injuries. Overall, footballers exhibited reduced spatial accuracy to a remembered location on an ocular motor memory guided task (p < 0.01), and reduced telomere length (p < 0.05) in comparison to controls; both findings were independent of concussion history and sex. Notably, shortened telomere length was associated with shortened memory guided latencies among Australian rules footballers (p < 0.001). These finding suggest that, even at the amateur level, Australian rules footballers have demonstrable neurological abnormalities relative to non‐collision sport control athletes. Importantly, these changes are measurable through both ocular motor assessment and analysis of telomere length, suggesting these methodologies might be sensitive biomarkers to monitor long‐term neurological health of collision sport athletes.
Keywords: Concussion, Biomarker, Ocular motor, Telomere, Collision sport, Australian rules football
DEPRESSION INDICATORS IN FORMER PROFESSIONAL RUGBY PLAYERS ARE RELATED TO NUMBER OF PLAYING YEARS AND NOT CONCUSSION HISTORY
1Trinity College Dublin, Dublin, Ireland
2Rugby Players Ireland, Dublin, Ireland
3University of Michigan, Ann Arbor, USA
Keywords: Depression
CLOSED HEAD INJURY MODELS OF MILD TRAUMATIC BRAIN INJURY: WHAT HAS BEEN DONE AND WHAT IS LEFT TO DO?
University of Kentucky, Spinal Cord and Brain Injury Research Center, Lexington, USA
With over 90% of all traumatic brain injuries (TBI) being mild in nature and over 10 million TBIs occurring annually worldwide, mild TBI (mTBI) is a major public health concern. Animal models are one of our most valuable tools for understanding mechanisms, and pathological outcomes of mTBI, as well as to test therapeutic interventions. While a variety of closed head models of mTBI that incorporate different aspects (i.e., biomechanics) have been developed, there are still many unanswered questions in the field. To summarize the current state of the mTBI field, this review compiles a comprehensive list of the closed head mTBI rodent models, along with the common data elements, and outcome measures. Publications were identified from a search of PubMed and Web of Science and screened for eligibility for a final list of 402 articles. Many of the common data elements collected were often unreported such as the material that the animal was placed on for the impact or the impactor tip shape. These elements of how the injury was delivered are essential for reproducibility of results. We also discovered that female and both young and aged animals are underrepresented in experimental mTBI studies. It is known that these groups respond to mTBI differently and thus it is a major issue that these groups are not more represented in studies. By using the data reported in this review, it is possible to identify major gaps in our current understanding of mTBI and better direct future research endeavors to propel the field forward.
Keywords: Animals Models, Common data elements, Injury mechanisms
FRACTIONATED MITOCHONDRIAL MAGNETIC SEPARATION FOR ISOLATION OF SYNAPTIC MITOCHONDRIA: IMPLICATIONS FOR NEUROTRAUMA RESEARCH
1University of Kentucky, Spinal Cord and Brain Injury Research Center, Lexington, USA
2UK, Department of Neuroscience, Lexington, USA
3UK, Department of Physiology, Lexington, USA
4Lexington VAMC, Lexington, USA
While mitochondria maintain essential cellular functions, such as energy production, calcium homeostasis, and regulating programmed cell death, they also play a major role in pathophysiology of many neurological disorders, including traumatic brain injury (TBI). TBI is associated with synaptic damage and synaptic mitochondrial dysfunction. Unfortunately, the ability to assess mitochondrial dysfunction and the efficacy of mitochondrial‐targeted therapies after experimental TBI is limited by current mitochondrial isolation techniques. Density gradient ultracentrifugation (UC) is currently the only technique that can separate synaptic mitochondrial sub‐population, though relatively low mitochondrial yield is achieved. To address this limitation, we used fractionated mitochondrial magnetic separation (FMMS), employing magnetic anti‐Tom22 antibodies, to develop a novel strategy for isolation of synaptic and non‐synaptic mitochondria from mouse cortex and hippocampus without the usage of UC. We compared the yield and functionality of mitochondria derived using FMMS to those derived by UC. FMMS produced 3x more synaptic mitochondrial protein yield compared to UC from mouse hippocampus. Additionally, tubulin levels in mitochondrial samples were significantly lower after FMMS compared to UC‐based separation (n = 6/group, p < 0.05), demonstrating higher sample purity. Finally, we utilized both FMMS and UC to examine non‐synaptic and synaptic mitochondrial function at 48h after repeated closed head injury (rCHI). Utilizing UC methods, neither fraction showed significant differences between rCHI and Sham groups. Using FMMS, State III oxygen consumption rate was lower in the non‐synaptic fraction after rCHI compared to Sham (n = 6/group, p < 0.05). Therefore, FMMS has increased sensitivity compared to UC separation to detect changes in mitochondrial respiration. Taken together, FMMS enables improved brain‐derived mitochondrial yield, higher sample purity and better detection of mitochondrial impairment in CNS injury and neurodegenerative disease.
Funding Sources: VA Merit Award 1I01BX003405‐01A1 and KSCHIRT Grant 14‐13A.
Keywords: methods, mitochondria, traumatic brain injury, synapse, Seahorse, MACs
EARLY LIFE STRESS IMPAIRS RECOVERY FROM MILD TRAUMATIC BRAIN INJURY
University of Miami Miller School of Medicine, Neurological Surgery, Miami, USA
Traumatic brain injury (TBI) is a major clinical problem in the United States. Mild TBI (mTBI) accounts for approximately 70‐90% of all TBIs. About 85% of these patients experience full functional recovery within two weeks, however, a subset of people exhibit persistent cognitive dysfunction for weeks to months after injury. The factors that contribute to persistent cognitive deficits after mTBI are unknown. One potential risk factor is early life stress. Early life stress includes maltreatment, such as neglect or abuse, and interferes with the normal construction of cortical and hippocampal circuits. We hypothesized that early life stress prior to mTBI exacerbates neuroinflammatory sequelae and impairs synaptic plasticity. To address this question, Sprague Dawley pups were separated from their nursing mothers for 3 hours daily from postnatal days 2‐14. At 2 months of age, the male rats received sham surgery or mild parasagittal fluid‐percussion brain injury (1.4‐1.6 atm). To determine whether early life stress exacerbates neuroinflammation after mTBI, inflammatory gene expression was measured in the hippocampus at 24 hours post‐injury. Using a PCR gene array for innate and adaptive immune molecules, we found that the combination of early life stress and mTBI upregulated the inflammatory genes toll‐like receptor 4 (Tlr4), NOD‐like receptor family, pyrin domain containing 3 (Nlrp3), caspase 1 (cas1) and interleukin‐1β (Il‐1β). To determine whether this upregulation in neuroinflammation corresponded to changes in synaptic dysfunction, we evaluated the long‐term potentiation (LTP) in area CA1 of the hippocampus. At 2 weeks post‐surgery, LTP was significantly impaired in mTBI animals exposed to early life stress as compared to non‐stressed mTBI animals. These results suggest that exposure to early life stress worsens recovery after mTBI by exacerbating neuroinflammation and impairing hippocampal synaptic plasticity.
Keywords: stress, long term potentiation, hippocampus, synaptic plasticity
SERUM SNTF, A SURROGATE MARKER OF AXONAL INJURY, RAPIDLY PREDICTS LASTING BRAIN DYSFUNCTION IN MILD TBI TREATED IN THE ER
1University of Pennsylvania School of Medicine, Neurosurgery, Philadelphia, USA
2Regions Hospital, Emergency Medicine, St. Paul, USA
Mild traumatic brain injury (mTBI), or concussion, causes persisting post‐concussion syndrome for many patients without abnormalities on conventional neuroimaging. Currently, there is no validated method for identifying at‐risk cases at an early and potentially treatable stage. SNTF is a calpain‐derived N‐terminal proteolytic fragment of spectrin (alphaII‐spectrin1‐1176) generated under neurodegenerative conditions, including in damaged axons following mTBI. Preliminary human studies provide evidence that elevated blood SNTF on the day of mTBI correlates with white matter disruption and lasting brain dysfunction. Here, we conducted a larger study evaluating serum SNTF as a rapid prognostic marker for persisting brain dysfunction in CT‐negative mTBI patients treated in an emergency department Level I trauma center setting. Compared with healthy controls (n = 40), serum SNTF increased by 92% within 24 hours of mTBI (n = 96; p < 0.0001), and as a diagnostic exhibited 100% specificity and 36% sensitivity (AUC = 0.87; p < 0.0001). To determine whether the subset of mTBI cases positive for SNTF preferentially developed lasting brain dysfunction, its serum levels on the day of mTBI were compared with multiple measures of brain performance at 30 and 90 days post‐injury. Elevated serum SNTF correlated significantly in group analyses with impairments at 90 days in cognition under stress and sensory‐motor integration, and predicted dysfunctional sensory‐motor integration on a case by case basis (AUC = 0.76; p = 0.006). SNTF also predicted poorer recovery of cognitive stress function determined from the difference in 90 and 30 day performance (AUC = 0.79‐0.90). These results indicate that serum SNTF, a surrogate marker for axonal injury after mTBI, has potential for the rapid prognosis of persisting post‐concussion symptoms and impaired functional recovery following CT‐negative mTBI, and provide further evidence linking diffuse axonal injury to chronic brain dysfunction. An SNTF blood test may have important utilities in the research, management and treatment of concussion.
Keywords: Blood test, calpain, Prognosis, Diagnosis, CT‐negative,
EFFECTS OF REPEATED AWAKE CLOSED HEAD INJURY ON CELL PROLIFERATION AND NEUROGENESIS IN JUVENILE RATS
1University of Victoria, Division of Medical Sciences, Victoria, Canada
2Faculdade de Ciencias Medicas Santa Casa de São Paulo, Sao Paolo, Brazil
Traumatic brain injury (TBI), is becoming increasingly recognized as a global health issue. Each year over 160,000 Canadians experience some form of TBI and around 1.5 million Canadians are currently affected by a TBI. Children are especially susceptible to repeat head injury and represent an at risk population for sustaining sports‐related concussions. Learning and memory dysfunction are common sequelae of TBI, which is likely a result of damage to the hippocampus, a structure that is particularly vulnerable to insults to the brain. This study uses a novel awake closed head injury (ACHI) model in male juvenile rats to investigate injury‐induced changes to the neurogenic niche following repeated mild traumatic brain injury. Following 8 repeated ACHIs, rats (n = 7 per group) were injected with BrdU and then sacrificed 2 hours later on post injury day 1, 3 or 7. A neurological assessment protocol (NAP) administered immediately after each impact showed that the ACHI alters consciousness acutely and results in neurological deficits after each impact. BrdU was used to identify mitotically active cells at those specific time points in addition to ki‐67, an endogenous marker for proliferation, doublecortin (DCX), a marker of mature neurons and NeuroD, a marker of late stage progenitors. A robust and diffuse increase in cellular proliferation revealed reactive gliosis and double labeling of GFAP and Iba1 expression was done to distinguish dividing neural stem cells from glial cells. By avoiding potential confounds of anaesthesia, this study helps further our understanding of potential innate repair mechanisms in the juvenile brain following repeat traumatic brain injury.
Keywords: mTBI, neurogenesis
REPETITIVE EXPERIMENTAL MILD TRAUMATIC BRAIN INJURY DOES NOT CAUSE NEURONAL LOSS EVEN IN THE CHRONIC PHASES OF INJURY
Virginia Commonwealth University, Anatomy and Neurobiology, Richmond, USA
Mild traumatic brain injury (mTBI), a major health care issue, can result in significant morbidity, particularly in repetitively injured individuals. Previously, we reported an increased number of axotomized neurons as a function of both number of injuries and injury severity following mTBI in mice (Ogino Y, et al. 2018). Despite the use of repetitive injury of differing severities, we found no evidence of neuronal death, a finding confirmed by electron microscopy. However, in these same animals, neurons positive for NeuN, a well‐known neuronal marker, decreased with increased injury severity. We hypothesized that NeuN expression may have been altered by injury itself, thereby contributing to this decrease. To test this hypothesis, we quantitatively assessed more prolonged neuronal survival in the same model of increased severity, using NeuroTrace, a fluorescent Nissl staining dye, in combination with DRAQ5, a nuclear dye, and NeuN. Mice surgically prepared for mild cFPI were given either a repetitive injury, a single injury followed by sham injury or a dual sham injury at a 3 h interval. Animals were allowed to survive for 24 h or 28 days after the initial injury. Fixed brains were sectioned at 40 μm and labeled with anti‐NeuN antibody and counterstained with NeuroTrace and DRAQ5. Fluorescent images captured with spinning disk confocal microscope were analyzed to quantify NeuN positive neurons interspersed among NeuroTrace‐labeled neurons using 3D‐image‐based methodologies. Initial results revealed no difference between experimental groups in the number of neurons positive for either NeuroTrace or NeuN. Eighty to ninety percent of the NeuroTrace‐labeled neurons expressed NeuN with no difference between groups. These results suggest no differences in neuronal survival in either the acute or chronic phases of TBI nor do they support the premise of reduced NeuN expression after experimental TBI. While further analyses remain to be done, these studies reinforce the concept that many forms of repetitive mild TBI do not elicit overt cell death. (NIH grant NS077675)
Keywords: repetitive TBI, mice fluid percussion injury
HEMATOLOGICAL CHANGES INDUCED BY POLYTRAUMA WITH CONCOMITANT CONCUSSION INVOLVE ALTERED COAGULOPATHY AND BIOMARKER LEVELS
1Walter Reed Army Institute of Research, Brain Trauma, Neuroprotection, and Neurorestoration, Silver Spring, USA
2Uniformed Services University of the Health Sciences, Department of Surgery, Bethesda, USA
Traumatic brain injury (TBI) is not an isolated injury to the brain but also results in widespread systemic changes to the blood involving coagulation, gas delivery, and ion balance. Importantly, the damage to brain can also result in the release of brain proteins to the blood. However, the hematological changes and biomarker levels are not well understood in patients that have sustained TBI with hypoxia and hemorrhagic insults.
To elucidate these changes, rats were divided into six groups: sham, hemorrhage and hypoxia (HH), single‐TBI (sTBI), repeated‐TBI (rTBI, 3x5min), sTBI+HH, and rTBI+HH. Hypoxia was induced following TBI/sham procedures by decreasing the inspired air to 10% oxygen for 60 minutes. Normoxia was returned and hemorrhagic shock was induced for 60 minutes before resuscitation with lactated Ringer's. Blood samples were collected immediately following these procedures for blood gas and thromoboelastography and at 2 or 24 hrs post‐injury for biomarker (GFAP, UCHL1, neurofilament‐light chain (NF‐L), tau) analysis. Indications of a hypercoagulable state was observed from HH, sTBI+HH, and rTBI+HH groups following resuscitation compared to sham (p < 0.05). These groups also demonstrated increased lactate levels and decreased oxygen in the blood (p < 0.05). The rTBI group showed similar pathology including an increased K value and decreased blood oxygen compared to sham (p < 0.05). The effects of HH were prominent on circulating biomarker levels. At 2 hours post‐injury, GFAP, UCHL1, and NF‐L were significantly increased in sTBI+HH and rTBI+HH groups. NF‐L was also increased in sTBI and rTBI groups. At 24 hours post‐injury, NF‐L had returned to sham levels but GFAP and UCHL1 remained increased compared to sham (p < 0.05). No significant changes were observed for tau. These results suggest that hemorrhage and hypoxia may exacerbate the TBI pathology and alter blood‐based biomarker dynamics.
Keywords: Penetrating brain injury, Hypoxia, Hemorrhage, Polytrauma, Biomarker
COGNITIVE AND WHITE MATTER PATHOLOGY OUTCOMES OF A MILITARY‐RELEVANT REPEATED CLOSED‐HEAD CONCUSSION ANIMAL MODEL
1WRAIR, Center for Military Psychiatry and Neuroscience, Silver Spring, USA
2Uniformed Services University of the Health Sciences, Bethesda, USA
Concussion is the most common type of TBI and military service members are at higher risk of experiencing concussions with higher incidence rate of post‐concussive syndrome. Since there are no therapeutics for TBI, development of a military‐relevant repeated closed‐head concussion animal model is important for preclinical testing of TBI therapeutics. In this study, anesthetized rats were exposed to repeated concussions by a spherical projectile impacting animal's helmet protected head. Animals were subjected to pair of concussions for either 1, 2, or 5 days. Time to regain righting reflex and sensorimotor deficits were assessed. Cognitive abnormalities were evaluated by using the Morris water maze (MWM) two weeks post‐injury. Approximately three weeks after the injuries, brains were collected and white matter abnormalities were assessed with H&E and silver‐staining. Multiple concussions (for either 2 or 5 days) produced injury severity dependent delays in recovery time of righting reflex and sensorimotor performance (p < .05 vs shams). Deficits in MWM performance in both the acquisition and retention testing periods were found only in animals exposed to concussions for 5 consecutive days (p < .001 vs. sham). Rats with 1 or 2 days of concussive injuries did not show any statistically significant deficits in the MWM (p > .05 vs. sham). Histological assessment showed an injury severity dependent pattern of reduction in corpus callosum thickness and white matter damage indicative of axonal pathology. White matter damage was widespread throughout the corpus callosum, thalamus, cortex, olfactory, and optic tracts in rats exposed to repeated concussions. However, a single set of concussions did not lead to white matter abnormalities. These results show that the WRAIR closed‐head concussion model represents a preclinical model of concussion that can be reliably used for the screening of TBI therapeutics.
Keywords: cognitive dysfunction, animal model, repeated concussions, neuroprotection
B06 Diagnostics
USEFULNESS OF BED SIDE PORTABLE ULTRASONOGRAPHIC EXAMINATION IN CRANIECTOMIZED TBI PATIENT. DISCREPANCY BETWEEN CT AND ULTRASOUND
Ajou University, Department of Neurosurgery, Suwon, Korea South
Decompressive Craniectomy is the effective surgery for severe traumatic brain injury patients and sometimes key procedure to survival. And after decompressive craniectomy, multimodal monitoring including imaging study is mandatory. CT scan is the most frequent imaging tool but it needs an effort that patient transfer and risk of radiation exposure. We tried ultrasound examination in craniectomized patients to prove its feasibility and usefulness as an imaging modality.
In a single institute, the patients who underwent decompressive craniectomy were enrolled. CT scan and portable ultrasound examination were done in all enrolled patients. The portable ultrasound device was made by GE (V‐scan). With ultrasonic gel, the transducer was contacted on the scalp at craniectomy site. Key images and some motion files were also stored. The ultrasound images were compared to CT scan in a PACS system. Identifiable parameters were measured. Midline shifting, size of hematoma was measured.
From 2017 Oct to 2018 Sep total 23 patients were selected. They were performed decompressive craniectomy due to traumatic brain injury. There were 15 males and 8 females (average age 54.7 years old). Compared with CT scan about swelling, herniation (midline shifting) and hemorrhagic progression. Ultrasound showed identifiable images that were similar to CT scans.
Portable ultrasound can provide useful images of the brain in craniectomized patients immediately without transfer to the CT scan room.
Keywords: Ultrasound examination, Craniectomized patient, ICU bedside imaging
ACUTE TRAUMATIC BRAIN INJURY CANDIDATE BIOMARKERS DISCOVERED BY PHAGE DISPLAY
Arizona State University, Tempe, AZ, USA
The heterogeneous injury pathophysiology of TBI is a barrier to development of diagnostic tools. Thus, biomarker discovery techniques that take advantage of this complexity are critical to the identification of biomarkers with higher specificity and sensitivity. We employed a unique pipeline for biomarker discovery that entailed domain antibody phage display, next generation sequencing (NGS) analysis, and nanotechnology strategies to generate antibody mimetics. Here, we will present the results from this discovery pipeline where biopanning was conducted in an acute brain injury mouse model. For in vivo phage biopanning, adult C57Bl/6 mice were anesthetized and subjected to either controlled cortical impact (CCI) or sham surgery (n = 3 per group/timepoint; approved by ASU IACUC). At 1 day post‐injury, domain antibody (dAb) phage library was intravenously injected and allowed to circulate for 10min. Mice were promptly sacrificed, and phage eluted from injured tissue and amplified for a second biopanning round. Peptide‐based antibody‐mimetics were selected from NGS data analysis using nanotechnology/biochemical conjugation strategies. Control peptides were created using dAb sequences that were identified in peripheral tissue. Proof‐of‐concept immunohistochemistry experiments were performed with peptides serving as a primary “antibody” on preserved tissue sections from CCI and sham brains. NGS analysis revealed select dAbs that were substantially enriched between biopanning rounds within the injury penumbra and not found in control libraries. Injury‐specific peptides were visualized with IHC and demonstrated positive recognition of features within the cortical injury penumbra, while no signal was observed in sham tissue. Furthermore, the negative control peptides did not bind to either injury or sham tissue, suggesting specificity of the injury‐peptide sequences. The pipeline of phage display followed by NGS analysis demonstrated a unique approach to discover biomarker candidates that are sensitive to the heterogeneous and diverse pathology present in neural injury. We successfully identified potential dAbs specific to acute cortical injury, as demonstrated by the spatial homing of peptide‐based antibody‐mimetics. Future studies will include immunoprecipitation‐mass spectrometry experiments to determine the antigen targets. Funding: NICHD DP2HD084067.
Keywords: Phage display, Next generation sequencing, Nanotechnology, Acute cortical injury
COMBINING SERUM LEVELS OF UCH‐L1, GFAP, AND NF‐L ENHANCES PREDICTION OF ACUTE TRAUMATIC BRAIN INJURY
Georgia Institute of Technology & Emory University, The Wallace H. Coulter Department of Biomedical Engineering, Atlanta, USA
We piloted the use of the combinations of serum concentration of glial fibrillary acidic protein (GFAP), neurofilament light (NF‐L), and Ubiquitin Carboxy‐terminal Hydrolase L1 (UCH‐L1) as a novel acute diagnostic biomarker of traumatic brain injury (TBI). Thirteen female, 4‐week‐old piglets received a diffuse‐TBI via rapid non‐impact head rotation (RNR, n = 7) or a focal‐TBI via controlled cortical impact (CCI, n = 4), and serum samples were obtained pre‐injury, at 1‐hour and 25‐hours post‐TBI in each subject. The concentrations of these proteins in serum were determined via N4PA‐assay (Quanterix SR‐X system, Lexington, MA). Following diffuse TBI, UCH‐L1 and GFAP were significantly elevated (Mann–Whitney test, P < 0.05) at 1‐hour post‐injury compared to pre‐injury (baseline) levels and were returned to baseline levels at 25‐hours post‐injury. Following focal TBI, GFAP was elevated significantly at 1‐hour post‐TBI compared to baseline level and was increased dramatically (> 50‐folds) at 25‐hours post‐TBI compared to 1‐hour post‐TBI and/or baseline level. Following focal TBI, the elevation of UCH‐L1 was not significant at either 1‐hour or 25‐hours post‐TBI compared to baseline level. Regardless of injury type, NF‐L showed longer temporal profile with significant increase at 25‐hours but not at 1‐hour post‐TBI. We combined focal and diffuse TBI data and performed uni‐multivariate binary logistic regression analysis to evaluate the ability of these biomarkers and their combinations to correctly identify serum from injured and uninjured animals. For diagnosis of TBI, serum UCH‐L1, GFAP, and NF‐L, individually, showed overall prediction accuracy rate of 59%, 82%, and 50%, respectively, at 1‐hour post‐TBI and 59%, 73%, and 82%, respectively, at 25‐hours post‐TBI. UCH‐L1 combined with NF‐L at 1‐hour post‐TBI and GFAP combined with NF‐L at 25‐hours post‐TBI were found to be the optimal biomarkers for TBI diagnosis, with 91% sensitivity and 91% overall prediction accuracy rate. In summary, we found that combinations of serum biomarkers outperformed any single serum biomarker in diagnosis of acute TBI either at 1‐hour or 25‐hours post‐TBI. Funded by NIH‐R01NS097549.
Keywords: Acute TBI Diagnosis, TBI Serum Biomarker, Multivariate Analysis, Diffuse and Focal TBI, Pre‐Clinical TBI Models, Large Animal Models of TBI
RELIABILITY OF SELF‐REPORTED CONCUSSION HISTORY IN CURRENT PROFESSIONAL RUGBY UNION PLAYERS
1Trinity College Dublin, School of Medicine, Department of Physiotherapy, Dublin, Ireland
2University of Michigan, NeuroTrauma Research Laboratory, Ann Arbor, USA
3University College Dublin, Leinster Rugby, Newstead Building A, Dublin, Ireland
Keywords: epidemiology, concussion, professional athlete, reliability, validity
INTERLEUKIN 10 AND HEART FATTY‐ACID BINDING PROTEIN AS EARLY OUTCOME PREDICTORS IN PATIENTS WITH TRAUMATIC BRAIN INJURY
1Turku University Hospital, Brain Injury Center, Turku, Finland
2University of Geneva, Department of Specialities of Internal Medicine, Geneva, Switzerland
3University of Gothenburg, Department of Psychiatry and Neurochemistry, Gothenburg, Sweden
4University of Cambridge, Division of Anaesthesia, Department of Medicine, Cambridge, UK
5University of Cambridge, Division of Neurosurgery, Department of Clinical Neurosciences, Cambridge, UK
Keywords: IL‐10, H‐FABP, Outcome
EXPANSION OF THE FORENSIC NURSING EXAMINATION TO SCREEN FOR TRAUMATIC BRAIN INJURY FOLLOWING INTIMATE PARTNER VIOLENCE
1University of Arizona, College of Medicine ‐ Phoenix, Phoenix, USA
2HonorHealth, Mesa Family Advocacy Center, Mesa, AZ
3The CACTIS Foundation, Scottsdale, AZ
4Phoenix Children's Hospital, Barrow Neurological Institute, Phoenix, AZ
5Phoenix VA Health Care System, Phoenix, AZ
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Keywords: Domestic violence, strangulation, post‐concussion symptoms, neurological signs, Concussion
RETINAL POLARIZATION SCANNING IDENTIFIES DEFICITS IN MILD TRAUMATIC BRAIN INJURY
1University of Pennsylvania, Neurology, Philadelphia, USA
2Boston University School of Medicine, Psychiatry and Neurology, Boston, USA
3Boston University College of Engineering, Boston, USA
4Rebion, Boston, USA
5Boston Children's Hospital, Boston, USA
6Harvard Medical School, Boston, USA
Mild traumatic brain injury (mTBI) accounts for about 75% of TBI diagnoses; however, mTBI can be difficult to diagnose due to vague and non‐specific symptoms, with no sensitive, reliable, objective tools to assist in diagnosis and prognosis. TBI can affect nearly every aspect of visual performance, including retinal nerve fiber structure, fixation stability, saccadic latency, and convergence; therefore, ocular function shows potential as a sensitive clinical indicator for mTBI. Rebion has developed a hand‐held device, the Head and Intraocular Trauma Test (HITT), that scans for ocular defects corresponding to dysfunction after TBI. HITT uses retinal polarization scanning to probe retinal nerve fibers noninvasively, detecting eye fixation with high precision. The device assesses retinal integrity, saccadic latency, fixation stability, and binocular alignment (convergence) in a 30‐second test. To assess the capacity of HITT to detect deficits in mTBI, we conducted a pilot study including 7 TBI subjects and 50 healthy controls aged 18‐50. All mTBI subjects had a GCS of 14‐15 on arrival to the emergency department. mTBI patients showed significantly lower average fixation stability (p = 0.008) and significantly lower binocularity score consistent with poor convergence (p = 0.003); there was also a trend toward longer average saccadic latency (p = 0.06). These results warrant replication to assess the potential for HITT to function as diagnostic and prognostic biomarker for patients suffering from mTBI.
Keywords: mild TBI, ocular defects, diagnostic, prognostic, biomarker
QUANTITATIVE EVALUATION OF SENSORY DYSFUNCTION IN TBI PATIENTS: PRELIMINARY REPORT
1VUMC, Nashville, USA
2VA, Tennessee Valley Healthcare System, Nashville, USA
3Blanchfield Hospital, Fort Campbell, USA
4Intrepid Spirit Center, Fort Campbell, USA
5VU, Nashville, USA
6WRNMMC, Bethesda, USA
Patients with mTBI frequently report sensory dysfunction despite normal clinical evaluations. This study employs a combined battery of tests intended to identify and quantify sensory deficits. Adult subjects are recruited from VA hospitals, VUMC, and Fort Campbell. Control participants had no recent history of a TBI and no eye/vision or ear/hearing problems. mTBI participants had a GCS of 13‐15 at time of injury. Subjects with obvious eye or ear damage were excluded. Each subject had optical coherence tomography, ophthalmic and ocular motor testing, audiometric assessments, evoked potentials, EEGs, and MRIs. We have assessed 8 mTBI and 22 control participants. Four of the mTBI and 8 of the control subjects were male. The average age (± sd) was 39.1 ± 11.0 for controls and 35.0 ± 12.5 years for mTBI subjects. The average time since injury was 6.6 ± 6.3 years. 60% experienced loss of consciousness, 50% reported mild vision problems, moderate sensitivity to light, or moderate to severe sensitivity to noise, and 25% reported mild hearing difficulties. As expected, all subjects had normal visual acuity and normal audiometric thresholds for pure tones. Convergence insufficiency was detected in 67% of mTBI and 5% of control subjects. mTBI subjects exhibited poorer performance for speech recognition in noise and regional thinning of the retina. We detected differences between groups even with this small number of subjects. Expansion of the study at Fort Campbell likely will rapidly and significantly increase our recruitment numbers.
Keywords: Auditory dysfunction, Visual dysfunction, EEG, MRI
B07 Edema
CHINESE TECHNICAL NOTES FOR DECOMPRESSIVE CRANIECTOMY IN ADULT PATIENTS WITH SEVERE TRAUMATIC BRAIN INJURY
1Department of Neurosurgery, the First Affiliated Hospital of Anhui Medical University, Hefei, China
2Department of Neurosurgery, Beijing Tian Tan Hospital, Capital Medical University, Beijing, China
3China National Clinical Research Center for Neurological Diseases, Beijing, China
4Neurotrauma Laboratory, Beijing Neurosurgical Institute, Capital Medical University, Beijing, China
The Neurotrauma Training Committee of the Chinese Medical Doctor Association has strongly promoted the use of decompressive craniectomy (DC) for the treatment of raised intracranial pressure (ICP) after severe traumatic brain injury (s‐TBI). In order to improve the quality of treatment provided by neurosurgeons across China and build the basis for future technical innovation, we present technical notes for performing DC in patients with s‐TBI in China. We introduced why we use DC, what is indications for DC. The DC included unilateral frontotemporoparietal DC (Patients with refractory high ICP caused by unilateral injuries or by multiple injuries which occur primarily on one side) and bifrontal DC (Patients with persistent high ICP caused by bilateral frontotemporal injuries or by diffuse brain swelling without obvious shift of the midline). Because of the complex and highly individualized condition of s‐TBI patients, a great deal of research remains to be done. Accelerating technological advances and the future development of large‐scale clinical research will ensure that our knowledge will continue to grow, leading to improved outcomes in these patients.
Keywords: Decompressive Craniectomy, Chinese Technical Notes, Traumatic Brain Injury
REPRODUCIBILITY OF CSF VOLUMETRICS FOR ESTIMATING BRAIN VOLUME IN TBI
1Portland State University, Build Exito, Portland, USA
2Oregon Health & Science University, Department of Neurology, Portland, USA
Cerebral edema (CE) following traumatic brain injury (TBI) has been linked to secondary injury and increased mortality. Conventional measurements of CE on head computed tomography (CT) (e.g., midline shift, basal cistern compression) inadequately account for CE due to bilateral lesions, atrophy, or lesions in distant compartments. Serial CSF volumetrics may afford advantages over conventional techniques by facilitating estimation of total brain volume between scans. We evaluated 10 admission head CT scans from an existing database of trauma patients with acute TBI. Using the Medical Image Processing, Analysis, and Visualization tool (MIPAV) freely accessible from the National Institute of Health, we measured the volumes of the intracranial vault and CSF spaces, and calculated total brain volume while adjusting for the presence of intraparenchymal lesions. To assess reproducibility, three non‐expert readers performed volumetric measurements on the same ten scans, and inter‐rater reliability was evaluated with intra‐class correlations (ICC) and Pearson's product moment correlations between each pair of raters. Confidence intervals (CI) are reported with significance set at p ≤ 0.05. Calculated brain volume had excellent reliability, ICC = 0.90 (95%CI 0.75 to 0.97). More variability was observed in the remaining measurements, though all were significantly different than the null. Sulci had moderate reliability, ICC = 0.78 (95%CI 0.5 to 0.93). Cisterns had moderate reliability, ICC = 0.61 (95%CI 0.23 to 0.87). Intracranial volume had moderate reliability ICC = 0.63 (95%CI 0.26 to 0.88). Ventricles had poor reliability ICC = 0.65 (95%CI 0.29 to 0.89). Comparisons of the pairs of raters revealed strong agreement between readers 1 and 2 (r = 0.80 to 0.99), and less agreement between 2 and 3 (r = 0.44 to 0.87), and 1 and 3 (r = 0.47 to 0.94). Reader 3 had less exposure to neuroanatomy than readers 1 and 2, who demonstrated strong agreement. Performance of CSF volumetrics with MIPAV might be a reproducible method to estimate brain volume by non‐expert readers if neuroanatomy is sufficiently reviewed.
Keywords: Volumetrics, MIPAV, TBI, Brain Volume
TRPM2 CHANNELS CONTRIBUTE TO BLOOD BRAIN BARRIER BREAKDOWN AND CEREBRAL EDEMA FOLLOWING TRAUMATIC BRAIN INJURY IN JUVENILE MICE
1University of Colorado Anschutz Medical Campus/Children's Hospital Colorado, Pediatric Critical Care Medicine, Aurora, USA
2University of Colorado Anschutz Medical Campus, Anesthesia, Aurora, USA
Traumatic Brain Injury (TBI) is a leading cause of morbidity and mortality in the pediatric population. Studies suggest that the non‐selective transient receptor potential M2 (TRPM2) channel may contribute to secondary brain injury. We hypothesized that genetic knockout of TRPM2 would result in reduced cerebral edema and reduced blood brain barrier breakdown in juvenile mice in a controlled cortical impact (CCI) model of TBI. P21‐P25 male and female mice, including wild type C57BL/6 and TRPM2 knockout mice, underwent 2mm depth CCI under standardized conditions. Following a 48‐hour recovery period, tissue was collected and processed for immunohistochemistry or calculation of cerebral edema. In TRPM2 knockout mice, immunohistochemical markers of blood brain barrier breakdown and neuroinflammation were reduced in comparison to wild type controls. Similarly, cerebral edema was reduced in male TRPM2 knockout mice in comparison to wild type controls (mean water content 79.8% vs 81.2%, respectively, p < 0.05). This study suggests that TRPM2 channels contribute to the breakdown of the blood brain barrier and the development of cerebral edema, contributing to secondary injury after TBI. Therefore, targeting TRPM2 channel activity may be a potential therapeutic approach to improve long‐term functional outcome following TBI.
Keywords: pediatric, traumatic brain injury
IMAGING ENDOPHENOTYPES AND EFFECTS OF SUR1 INHIBITION IN TWO MOUSE MODELS OF TBI
1University of Pittsburgh, Critical‐Care‐Medicine, Pittsburgh, USA
2Children's Hospital(UPMC), Developmental‐Biology, Pittsburgh, USA
Cerebral edema endophenotypes in different TBI models may respond variably to targeted sulfonylurea receptor‐1 (Sur1) inhibition. We assessed Sur1 inhibition with glyburide or ABCC8‐/‐ (the Sur1 gene) mice using Magnetic Resonance Imaging (MRI) in mouse models of controlled cortical impact (CCI) and CCI+hemorrhagic shock (CCI+HS). Anesthetized mice underwent CCI or CCI+HS (mean arterial pressure = 25‐27mmHg, 35 min). For both models, male C57/BL6 mice were divided into 3 groups (n = 5/group): naïve, injury+vehicle, injury+glyburide. Additional experiments in both models were performed using ABCC8‐transgenic mice divided into 4 groups (n = 3‐5/group): ABCC8‐/‐ with injury, WT+injury, WT‐naive, ABCC8‐/‐naive. MRI was obtained at 3h, 6h, 24h and 7d (n = 188 scans). Edema‐volume (EV, ml), injury blood‐volume (IBV, ml), apparent‐diffusion coefficient (ADC, 10−3mm2/s), and T2‐quantification (ms) were assessed. Model comparison: Vasogenic T2‐EV was higher in CCI+HS (46.0 ± 5.7) vs CCI (31.5 ± 4.0) over all 7d. IBV was higher in CCI (21.8 ± 2.5) vs CCI+HS (12.0 ± 3.6). CCI+HS had higher T2‐hyperintensity in ipsilateral‐cortex (T2‐ic) than CCI or naive at 3h (83.2 ± 3.9 vs 67.6 ± 1.5 vs 49.6 ± 3.9) and 6h (88.4 ± 4.0 vs 70.9 ± 1.5 vs 48.9 ± 4.0). 3h ADC‐ic (mm2/s) was more restricted after CCI (0.65 ± 0.02) vs CCI+HS (0.81 ± 0.06) or naïve (0.84 ± 0.06). All p < 0.05. Sur1 inhibition: By 7d after CCI+HS, glyburide reduced vasogenic EV vs vehicle (27.4 ± 2.3 vs 51.4 ± 6.2). This also occurred in ABCC8‐/‐ vs WT (14.4 ± 0.9 vs 29.2 ± 3.0). CCI+HS 7d T2‐ic was lower in naïve (50.9 ± 7.8) and glyburide (66.4 ± 3.0) vs vehicle (87.3 ± 8.2). In contrast, Sur1 inhibition did not affect EV after CCI, although 7d IBV was lower in ABCC8‐/‐ (5.3 ± 0.5) vs WT(10.1 ± 1.5). All p < 0.05. Our data suggest markedly different MRI endophenotypes in CCI vs CCI+HS: extensive EV and T2‐hyperintensity in CCI+HS represent a robust penumbral Sur1 target. In CCI alone, Sur1‐inhibition effects were more modest. Consistent with gradual Sur1 upregulation, benefits manifest by 7d. Our findings may influence future clinical trial design.
Support:NINDS‐K23NS101036
Keywords: sulfonylurea receptor‐1, glyburide or glibenclamide, magnetic resonance imaging (MRI), cerebral edema, vasogenic edema
B08 Electophysiology
GENDER DIFFERENCE IN MICTURITION OF RATS AFTER SPINAL CORD INJURY
1Indiana University, Neurosurgery Department, Indianapolis, USA
2Indiana University, Anatomy and cell biology, Indianapolis, USA
Keywords: spinal cord injury, micturition, urination, urodynamic, detrusor, external urethral sphincter
FUNCTIONALITY OF GASTRIC TTX‐RESISTANT NAV CHANNELS IN NODOSE GANGLIA OF SPINAL CORD INJURED RATS
1Penn State College of Medicine, Neural and Behavioral Sciences, Hershey, USA
2Penn State College of Medicine, Anesthesiology and Perioperative Medicine, Hershey, USA
We have demonstrated post‐SCI vagal afferent insensitivity to both gastrointestinal peptides and mechanical stimuli. Voltage‐gated sodium (NaV) channels are essential for the rising phase and threshold of action potentials and three NaV subtypes (NaV 1.7, 1.8 and 1.9) are expressed in the nodose ganglion (NG). The NaV 1.8 and 1.9 channels are characterized by their resistance to tetrodotoxin (TTX‐R) while NaV 1.7 channels are TTX‐sensitive. The contributions of NaV 1.7, 1.8 and 1.9 channels in vagal afferent neurotransmission remains unclear in many disease states and is completely unknown after SCI. We hypothesized that reduced sensitivity of SCI gastric vagal afferents is due to decreased expression and current density of TTX‐R NaV channels. Male Wistar rats received a contusion T3‐SCI or laminectomy control prior to experimentation. Gastric vagal afferents were retrogradely traced with DiI, and the NG was dissociated to single cells. Voltage‐clamp recordings in the presence of TTX were conducted to assess Nav 1.8 and 1.9 biophysical properties following SCI. Gastric‐projecting NG neurons were also collected for single cell qRT‐PCR analysis of NaV 1.7, 1.8 and 1.9 mRNA expression. NaV 1.7 mRNA expression was elevated 3‐fold while NaV 1.9 mRNA was elevated over 500‐fold. NaV 1.8 expression was inconclusive. In control cells, exclusive NaV 1.8 currents were recorded in 44/57 cells. Mixed NaV 1.8 + 1.9 currents were in 13/57 cells. No exclusive NaV 1.9 currents were observed. In SCI cells, exclusive NaV 1.8 currents were recorded in 42/64 cells. Mixed NaV 1.8 + 1.9 currents were in 11/64 cells and exclusive NaV 1.9 currents were in 11/64 cells. Nav 1.8 current density was unaffected by SCI; however, the TTX‐R NaV 1.9 channel shows altered kinetics after SCI. The alterations of these complex electrophysiological phenotypes (including NaV 1.7) exhibited in vagal afferents after SCI requires further analysis, including the chronic phase of SCI. Support: NS049177
Keywords: Spinal Cord Injury, Nodose Ganglia, Voltage‐gated Sodium Channels, Gastric, TTX‐resistant
PURINERGIC DYSREGULATION IN GASTRIC VAGAL AFFERENTS AFTER SPINAL CORD INJURY
Emily Blanke1, Emily Besecker3,1, Victor Ruiz‐Velasco2,
1Penn State Univ. College of Medicine, Neural & Behavioral Sciences, Hershey, USA
2Penn State Univ. College of Medicine, Anesthesiology and Perioperative Medicine, Hershey, USA
3Gettysburg College, Health Sciences, Gettysburg, USA
Gastrointestinal (GI) dysfunction is indicative of the whole‐body change in physiology brought about by spinal cord injury (SCI). Emerging evidence is associating the post‐SCI systemic inflammatory response with this multiorgan dysfunction. Our previous data has shown diminished signaling of intact gastric vagal afferents after SCI. Studies of systemic inflammation demonstrate remodeling of the vagal afferent cell bodies and satellite glial cells within the nodose ganglion (NG) through a purinergic signaling cascade that includes the P2X3 receptor. The NG P2X3 receptor is upregulated following chronic SCI and this suggests that sensitivity of vagal afferents may be differentially regulated depending upon the level of NG purinergic stimulation that accompanies SCI. We hypothesized that T3‐SCI will increase gastric‐projecting NG P2X3 receptor expression and P2X current density. Male Wistar rats received a contusion T3‐SCI at 3 days or 3 weeks prior to experimentation. Gastric vagal afferents were retrogradely traced with DiI, and nodose ganglia (NG) were dissociated to single cells. The expression of the P2X3 receptor in gastric‐projecting afferents was analyzed with immunohistochemistry paired with confocal imaging. Whole cell patch clamp recordings assessed either ATP currents in dissociated gastric NG cells following exposure to 10μM Bz‐ATP or voltage‐gated sodium (NaV) currents following overnight incubation of dissociated cells with low (1μM) or high (50μM) Bz‐ATP. The expression of P2X3 receptor‐positive gastric‐projecting NG neurons was increased in 3 day SCI animals with greater cytoplasmic localization whereas P2X3‐positive labeling decreased in 3 week SCI animals. Native P2X currents were lower in NG neurons from 3 day SCI rats. NaV currents were elevated by incubation with low concentration Bz‐ATP and decreased by high concentration Bz‐ATP. The gastric vagal afferent dysfunction following SCI may occur because of an initial upregulation of the P2X3 receptors within the NG inducing excitotoxicity. Support: NS049177, Gettysburg College Internal Award
Keywords: Autonomic nervous system, Gastrointestinal dysfunction, Vagus nerve, Afferent signaling, Nodose ganglia, Purinergic signaling
INTRACORTICAL ELECTROENCEPHALOGRAPHY IN PEDIATRIC SEVERE TRAUMATIC BRAIN INJURY
Phoenix Children's Hospital, Neurosciences, Phoenix, USA
Keywords: Traumatic Brain Injury, Electroencephalography, Multimodal Neuromonitoring, Quantitative EEG, Neurocritical Care
ELECTROPHYSIOLOGICAL CHANGES IN THE HIPPOCAMPUS AFTER MILD CONTROLLED CORTICAL IMPACT
University of Pennsylvania, Bioengineering, Philadelphia, USA
Keywords: electrophysiology, mild TBI, controlled cortical impact, hippocampus
A TRANSLATIONAL MODEL OF POST‐TRAUMATIC EPILEPTOGENESIS
1University of Pennsylvania, Neurosurgery, Philadelphia, USA
2Veterans Affairs, Medical Center, Philadelphia, USA
Traumatic brain injury is a complex and heterogeneous injury that often involves both focal and diffuse pathologies. While TBI is a major cause of epilepsy in both military and civilian populations, the mechanisms underlying the development of post‐traumatic epilepsy remain unclear. We therefore developed a unique porcine model of controlled cortical impact (CCI) injury, which recapitulates both focal and diffuse pathologies observed in human TBI. Male Yucatan miniature pigs were injured at 6 months of age and assessed for any neurological deficits. We implemented a Large Animal Custom Enclosure System (LACES), a 64‐channel wireless recording system designed for use with a 32‐channel hippocampal probe, a 24‐channel cortical probe, and 4 bilaterally placed ECoG screws. This system allows for 24/7 video monitoring of awake behaving pigs, with alternate days of monitoring of the electrophysiological signals. Changes in neurophysiological signals were monitored for epileptogenesis and disturbances in sleep‐wake states. We found that CCI‐injured (n = 5) but not sham (n = 4) animals presented with a functional deficit that recovered at 72 hours post injury. Using electrophysiological recordings (sham = 2, injured = 2), we demonstrated that the brain is abnormally excitable for up to 8 months post CCI injury. At 1‐month (n = 2), the animals developed epileptiform activity in the cortex in the form of spikes, bursts, and slow wave discharges. At 4 months, electrographic seizures were observed in both hippocampus and cortex during sleep and awake states, and they became synchronized at 8‐month post injury (n = 1). Moreover, injured animals showed marked alterations in sleep patterns, with significantly more time spent in non‐REM vs. REM sleep. While the CCI injury model leads to substantial cortical and axonal pathology at acute time points, it also has the potential for inducing electrographic seizure activity over time. Exploring the circuit level changes in parallel with neuropathology may provide a powerful translational approach to understand the relationship between TBI and epileptogenesis. Funding: DoD ERP CDMRP W81XWH‐16‐1‐0675 and CURE‐TA PTE.
Keywords: TBI, PTE, pig, awake in‐vivo recordings, electrographic seizure, sleep states
COMPARATIVE STRIATAL DA NEUROTRANSMISSION CHARACTERISTICS IN CARDIAC ARREST VS. TRAUMATIC BRAIN INJURY
1University of Pittsburgh, Physical Medicine, Rehabilitation, Pittsburgh, USA
2University of Pittsburgh, Safar Center for Resuscitation Research, Pittsburgh, USA
3University of Pittsburgh, Critical Care Medicine, Pittsburgh, USA
4Duquesne University, School of Pharmacy, Pittsburgh, USA
5University of Pittsburgh, Center for Neuroscience, Pittsburgh, USA
6University of Pittsburgh, Anesthesia, Perioperative Medicine, Pittsburgh, USA
Traumatic brain injury (TBI) and Cardiac arrest (CA) survival rates have improved with modern clinical care, but survivors experience functional impairments after their insult. TBI and CA survivors exhibit similarly reduced arousal and behavioral/cognitive symptoms, indicating striatal dopamine (DA) dysfunction; both populations are often treated similarly, with DA agonists. However, the molecular underpinnings of these sequelae, their injury type differences, and their impact on DA neurotransmission are largely unknown. We hypothesized CA‐induced medium spiny neuron dysfunction and TBI‐induced cortical deafferentation would produce different DA neurotransmission effects. Anesthetized, adult male Sprague‐Dawley rats (n = 43) underwent controlled cortical impact (CCI) injury (4m/s velocity, 2.8mm lesion‐depth), 5‐minute CA, or were naïve. TBI‐sham and CA‐shams underwent similar procedures excluding the respective insult. Fast‐scan cyclic voltammetry was used with median forebrain bundle electrical stimulations (60Hz, 10s) to characterize presynaptic dorsal striatum (D‐STR) DA neurotransmission 14‐days after TBI/sham or CA/sham surgery. 8 of 9 CCI animals produced negligible D‐STR DA overflow, though simultaneous nucleus accumbens (NAc) recordings showed typical DA neurotransmission. CCI had significantly lower maximum evoked D‐STR DA overflow versus CCI‐Sham/Naïve. Alternatively, CA had higher maximum DA overflow versus CA‐shams (p < 0.0001). CCI also had lower DA release and DA reuptake maximal velocity (Vmax) versus CCI‐Sham/Naïve, whereas CA had higher DA release and Vmax values in D‐STR versus CA‐Sham (p < 0.05 both comparisons). Striatal DA transporter and tyrosine hydroxylase expression varied across models. These data have implications for CA and TBI treatment, suggesting precision medicine approaches may require further pre‐clinical comparative assessment to optimize recovery and DA therapeutics for TBI and CA survivors. Support: 1R21NS108386‐01A1
Keywords: Dopamine, Fast Scan Cyclic Voltammetry, Neurotransmission
RELIABLE MAGNETOENCEPHALOGRAPHIC MEASURES IN CHRONIC POST‐CONCUSSIVE SYNDROME ‐ A TEAM‐TBI STUDY
University of Pittsburgh, Neurological Surgery, Pittsburgh, USA
Magnetoencephalography (MEG) enables safe, non‐invasive measurement of human brain function with high temporal fidelity and spatial resolution. We established normative neuroelectric measures for 168 cortical and subcortical brain regions, for 18 deep white matter tracts, and for normative activity patterns using MEG recordings, healthy volunteers, n = 591, ages: 18‐87, Cam‐CAN cohort.
64 participants were recruited from the TEAM‐TBI trial, a prospective targeted interventional trial in adults with chronic (more than 6 months) post‐concussive symptoms. We compared their regional measures and patterns to the norms (a) to assess the integrity of each tract in each individual and (b) to assess the normality of the pattern of each individual. Repeat reliability of each measure and pattern for each individual was confirmed by comparing baseline to follow‐up studies, mean interval: 16.1 months (Cam‐CAN), 6.4 months (TEAM‐TBI).
Five of the TEAM‐TBI cohort demonstrated significantly reduced activity in multiple deep white matter tracts, p < 10−3 for each. Five more showed moderate reductions. All 64 of the TEAM‐TBI cohort showed patterns at baseline which were outside the range of the norms. 12 of the 39 with follow‐up studies moved more than two standard deviations toward the norm at follow‐up. This subgroup showed significant improvement (p = 0.02) in sleep disturbances (Insomnia Severity Index) and reductions in somatization, depression, and anxiety (Brief Symptom Inventory). The Alcohol Use Disorders Identification Test (AUDIT) did not change.
We demonstrate reliable identification of functional compromise to single deep white matter tracts in individuals and detailed measures of regional activity which characterize the normality of the tonic pattern of brain activity. MEG recordings provide precise and reliable physiological measures with significant potential for clinical utility. This may prove sufficient to enable both targeting and treatment monitoring for drug therapies and transcranial magnetic stimulation. Support: Department of Defense #13154004, University of Cambridge (UK) Centre for Ageing and Neuroscience (Cam‐CAN), Open Science Grid, Extreme Computing Consortium (XSEDE).
Keywords: magnetoencephalography, concussion, sleep disorder, diagnostics, deep white matter tracts, shared data
B09 Inflammation / Immune Function
FLOW CYTOMETRIC ANALYSIS OF BLOOD AND BRAIN INFLAMMATORY PROCESSES TRIGGERED BY MODERATE TBI IN A RAT MODEL
French Armed Forces Biomedical Research Institute, Bretigny‐sur‐Orge, France
To date, all attempts to reach a clinical benefit in human traumatic brain injury (TBI) using immune‐dampening strategies have failed. This might reflect the complexity and dual role (neuroprotective/reparative vs. maladaptative/neurotoxic) of immune‐inflammatory processes triggered by TBI. Here, we used flow cytometry to precisely identify the immune cells recruited to the blood and brain compartments following moderate TBI, and try to refine inflammation‐based therapies. Adult rats were exposed to moderate fluid percussion injury and were euthanized 24 hours, 1 week and 1 month thereafter. Blood was collected under anaesthesia, then rats were transcardially perfused with saline and their brain was removed. Brains were split into a traumatized (ipsilateral/left) and a contralateral part. Blood and brain samples were processed to detect and quantify immune‐inflammatory cells using flow cytometry. TBI caused massive inflammation in the traumatized, but not the contralateral, brain side. At 24 hours post‐TBI, there was a transient decrease in the density of microglial cells (CD45low/cd11b‐c+), that was not observed at later stages. Nevertheless, the sub‐population of activated microglia (MHCII+) was drastically increased up to 1 month post‐TBI. We also detected an outstanding increase (x 5‐6) in the density of myeloid blood‐derived cells (CD45high/cd11b‐c+) at 24 hours post‐TBI. While the myeloid cell population in brains of control rats seemed diffuse, three distinct and compact sub‐populations could be separated in the traumatized brain. This increase in myeloid cell density was observed throughout the first month post‐TBI, although the three myeloid sub‐populations observed 24 hours post‐TBI were not present at later stages. The most remarkable inflammatory process measured in blood samples was a dramatic increase in the density of neutrophils at 24 hours post‐TBI. Thus, moderate TBI triggers different inflammatory sequences over time. Future studies will examine the expression of pro‐ and anti‐inflammatory markers in all the immune‐inflammatory populations recruited following TBI. This work was supported by a grant from the French Ministry for Armed Forces.
Keywords: TBI, animal model, inflammation, flow cytometry
SYSTEMATIC REVIEW OF GENETIC RISK FACTORS FOR TRAUMATIC BRAIN INJURY (TBI)
Hennepin County Medical Center/ University of Minnesota‐Twin Cities, Neuroscience, Minneapolis, USA
Traumatic Brain Injuries (TBI) cause extensive morbidity and mortality with variable penetrance after exposure. The genetics of injury impacts not only exposure but also outcome. This review aims to identify and categorize genetic influencers of TBI based on pre‐injury impulsivity, aggression, and ADHD‐like symptom risk, short term edema and non‐edema risk, and predisposition to negative long‐term outcomes following TBI. 29 genes were identified: 7 as potential influencers of pre‐injury risk, 6 influencing symptoms associated with short‐term edema, 5 influencing symptoms associated with short‐term non‐edema, and 11 influencing predisposition to negative long‐term outcomes. While investigations of genetic impact and influence on traumatic brain injury are still developing, using such genetic indicators has the potential to aid the diagnostic and prognostic processes involved.
Keywords: Epigenetics, Long‐Term, Short‐Term, Edema, Non‐Edema
XENON REDUCES SECONDARY INJURY, PREVENTS NEURONAL LOSS AND NEUROINFLAMMATION IN A RAT MODEL OF TRAUMATIC BRAIN INJURY
1Imperial College London, Surgery and Cancer, London, United Kingdom
2Imperial College London, Royal British Legion Centre for Blast Injury Studies, London, United Kingdom
3Charing Cross Hospital, Critical Care Medicine, London, United Kingdom
4Imperial College London, Life Sciences, London, United Kingdom
5Royal Berkshire Hospital, Anaesthetics, Reading, United Kingdom
Keywords: xenon, neuroprotection, neuroinflammation
SHORT VS LONG‐TERM TOLL‐LIKE RECEPTOR 4 INHIBITION HAS OPPOSITE EFFECTS ON INFLAMMATION AND COGNITIVE OUTCOMES AFTER TBI
Johns Hopkins University, Pediatric Surgery, Baltimore, USA
Keywords: Monocyte, Pharmacologic Therapy, Neuroinflammation inhibition, Toll‐Like Receptor 4
PHARMACOLOGICAL BLOCKADE OF LEUKOTRIENE SYNTHESIS AMELIORATES NEUROINFLAMMATION AND REACTIVE GLIOSIS FOLLOWING REPETITIVE MILD TBI
1Roskamp Institute, Neuroscience, Sarasota, USA
2Open University, Milton Keynes, United Kingdom
Keywords: Repetitive mild Traumatic Brain Injury, Neuroinflammation, Bioactive Lipids, Leukotrienes, Zileuton, Montelukast
TYPE I INTERFERONS DRIVE NEUROINFLAMMATION AND NEURODEGENERATION FOLLOWING EXPERIMENTAL TRAUMATIC BRAIN INJURY IN MICE
1University of Maryland, STAR‐ORC, Baltimore, USA
2University of Maryland, Department of Microbiology and Immunology, Baltimore, USA
The present study examined the role of the type 1 interferon (IFN) β in mediating the inflammatory response following traumatic brain injury (TBI), and evaluated the effects of IFN inhibition on secondary neuroinflammation and long‐term neurological recovery. Experiment 1: Male C57BL/6J mice underwent moderate‐to‐severe controlled cortical impact (CCI) and brain tissue was isolated at 1 and 3 days post‐injury (DPI) for molecular analysis. Experiment 2: Male C57BL/6J and IFNβ‐null (IFNβ‐/‐) mice underwent CCI and brain tissue was isolated at 3 DPI for mRNA and protein analysis. Experiment 3: Male C57BL/6J and IFNβ‐/‐ mice underwent CCI. Cognitive and motor function were assessed through 28 DPI. At 28 DPI, brains were removed and fixed for histological analysis. Experiment 4: 30 minutes after CCI, male C57BL/6J received a 3 day intracerebroventricular infusion of a neutralizing antibody to IFNAR1 (mouse anti‐IFNR1 Ab, clone MAR1‐5A3) or mouse IgG1 isotype control (clone MG1‐45) using Alzet infusion pumps. Cognitive and motor function was assessed and at 28 DPI, brains were removed and fixed in for histological analysis. We demonstrate CCI results in increased expression of the DNA sensors Cyclic GMP‐AMP synthase (cGAS) and Stimulator of Interferon Genes (STING). In addition, IFNβ and IFN‐related genes are significantly increased after TBI. Gene expression of several pro‐inflammatory mediators were significantly attenuated in IFNβ‐/‐ mice when compared to WT CCI mice. CCI‐induced deficits in cognitive and motor function were significantly decreased in IFNβ‐/‐ mice compared to WT mice. Moreover, tissue loss was significantly decreased in IFNβ‐/‐ mice when compared to WT CCI mice. Administration of a neutralizing antibody to IFNAR1 reversed CCI‐induced cognitive impairments and improved motor function. These data demonstrate that TBI induces activation of cGAS/STING and upregulation of Type I IFN related genes. Furthermore, IFNβ deficiency reduces markers of pro‐inflammatory neuroinflammation, limits tissue loss and improves neurological recovery after moderate‐level CCI.
Keywords: Type I Interferon, Secondary Injury, Microglia, DNA damage
POST‐INJURY SLEEP DISRUPTION CAUSES IMMEDIATE AND DELAYED ALTERATIONS IN THE INFLAMMATORY RESPONSE TO TRAUMATIC BRAIN INJURY
1The Ohio State University College of Medicine, Department of Neuroscience, Columbus, USA
2The Ohio State University Neurological Institute, Insititute for Behavioral Medicine Research, Columbus, USA
3The Ohio State University College of Dentistry, Division of Biosciences, Columbus, USA
Mounting evidence shows that chronic sleep/wake disruption is a significant stressor that promotes inflammation, leading to brain dysfunction and behavioral impairment. We predict that maladaptive changes in the hypothalamic pituitary axis following traumatic brain injury (TBI) compromise the inflammatory response to post‐injury sleep disruption (SD). As a result, neuroinflammation persists. The purpose of this study was to determine the immediate and delayed inflammatory effects of transient post‐injury SD. Lateral fluid percussion TBI or sham injury was administered to an equal number of male and female C57BL/6 mice aged 2 months. Half of the mice in each group were exposed to 4 hours of SD from 7‐11am for 3 consecutive days post‐injury (DPI). Novel data show that the plasma corticosterone (CORT) response to SD was blunted in TBI mice, indicating that CORT‐mediated negative feedback was compromised after brain injury. Moreover, neuroinflammation in brain areas directly affected by TBI was enhanced after SD, as shown by increased peripheral leukocyte recruitment to the injured cortex, increased cortical Iba1 and Gfap immunolabeling, and elevated expression of cortical inflammatory mediators, such as Tlr4, Trem2, and Tnfa. Strikingly, these neuroinflammatory alterations in TBI SD mice persisted 7 DPI, four days after SD concluded. Together, these results support the hypothesis that SD is an immune stressor that significantly alters outcome from TBI. These data provide new insight into the dynamic interplay between TBI, SD, and outcome.
Keywords: Neuroinflammation, Sleep disruption, TBI, sleep, stress
IMMEDIATE AND DELAYED INFLAMMATORY EFFECTS OF CHRONIC SLEEP FRAGMENTATION AFTER TRAUMATIC BRAIN INJURY
The Ohio State University Wexner Medical Center, Neuroscience, Columbus, USA
Homeostatic sleep/wake behavior requires coordinated engagement of endocrine pathways, which become dysregulated after traumatic brain injury (TBI). Sleep fragmentation (SF) is common in post‐injury sleep disorders, such insomnia and sleep apnea, that affect up to 75% of TBI patients and can persist years after injury. Experimental models of TBI alone fail to recapitulate these chronic deficits in sleep/wake behavior. Thus, we predict that SF is a controlled experimental method to directly engage and interrupt endocrine coordination and consequently worsen neuroinflammation. To test this, equal numbers of male and female C57BL/6 mice were given lateral fluid percussion TBI or sham‐injury. Half the animals in each group were exposed to transient SF from 7‐11 AM for 30 days while the remaining animals were undisturbed. This resulted in four experimental groups: Sham, Sham SF, TBI, and TBI SF. As expected, TBI increased Iba‐1 and GFAP immunoreactivity in ipsilateral cortical and sub‐cortical areas 30 days post‐injury (DPI). Notably, these responses were exaggerated in TBI SF mice compared to all other groups. To examine the delayed effects of post‐injury SF, separate cohorts of mice were exposed to 30 days of SF and then remained undisturbed for an additional 30 days. TBI‐induced increases in Iba‐1 and GFAP immunoreactivity persisted in ipsilateral cortical and sub‐cortical areas 60 DPI. Further, TBI SF mice continued to display exaggerated immunoreactivity in sub‐cortical areas at 60 DPI compared to all other groups. Together, these data indicate that chronic transient sleep disruption is sufficient to alter the neuroinflammatory response to TBI and highlight the influence of endocrine‐immune pathways in mediating post‐injury recovery. Continued characterization of post‐TBI SF will better define how stressors, such as chronic sleep/wake disruption, influence endocrine and immune axes to compromise post‐injury recovery and contribute to long‐term consequences of TBI.
Keywords: neuroinflammation, sleep fragmentation, chronic TBI, sleep, stress
MODERATE CHIMERA INJURY ELICITS DIFFERENTIAL ACUTE INFLAMMATORY RESPONSES IN HUMANIZED APOE3 AND APOE4 TARGETED‐REPLACEMENT MICE
1University of British Columbia, Pathology and Laboratory Medicine, Vancouver, Canada
2Pfizer Inc, Internal Medicine Research Unit, Cambridge, United States
3Pfizer Inc, Medicine Design, Cambridge, United States
The CHIMERA is a biofidelic model of impact‐acceleration head injury that replicates multiple characteristics of clinical traumatic brain injury (TBI) including elevated plasma biomarkers, grey and white matter inflammation, and microvascular injury. This study was designed to evaluate the influence of apolipoprotein E (apoE) genotype on TBI outcomes. ApoE is the main lipid carrier in the brain with important roles in microglial phenotype, cerebrovascular function and injury repair. The study was also designed to test the effects of modulating apoE activity on TBI pathophysiology using liver X receptor agonist GW3965. Four‐month old apoE3 and apoE4 human targeted‐replacement male mice were randomized to sham or CHIMERA TBI (1x 2.2J) groups, after which they were treated with vehicle or GW3965 (subcutaneous) at 20 mg/kg 30 min post‐injury. A group was sacrificed at 6h post‐TBI, whereas a second group received vehicle or GW3965 every 24h until sacrifice at 7d. Immediately after injury, we observed that apoE4 mice showed greater levels of respiratory apnea and fatal cardiac arrest, compared to apoE3 controls. In surviving animals, apoE3 mice had a significantly longer loss of consciousness duration compared to apoE4 mice. Biochemical analyses revealed a significant injury effect in cytokine levels (TNFα, IL‐6, IL‐1β) at both 6h and 7d time‐points. Intriguingly, vehicle‐treated apoE4 mice showed inhibited IL‐6 and IL‐1β responses following CHIMERA TBI, both of which were restored to apoE3 levels after one dose of GW3965. Silver staining in the optic tract revealed an injury effect, drug effect, and an injury‐drug interaction, with the greatest evidence of silver uptake observed in GW‐treated apoE4 mice subjected to TBI at 7d post‐TBI. Our preliminary findings suggest apoE genotype modifies several acute outcomes after CHIMERA injury.
Keywords: CHIMERA, Apolipoprotein E, Inflammation, Axonal injury
A NOVEL METHOD OF PRODUCING BEHAVIOURAL AND PHYSIOLOGICAL CHANGES FROM MILD TRAUMATIC BRAIN INJURY IN MICE
1University of Calgary, Psychology, Calgary, Canada
2Monash University, Neuroscience, Melbourne, Australia
3University of Calgary, Cell Biology and Anatomy, Calgary, Canada
4University of Calgary, Hotchkiss Brain Institute, Calgary, Canada
Traumatic Brain Injury (TBI) is one of the most common adolescent health issues with the vast majority of all TBI cases being mild (mTBI). The causes of mTBI include falls, automobile accidents, and sports injuries. Common post‐concussive symptomology associated with mTBI include motor, cognitive, affective, and somatic behavioural deficits. Here, we have developed a novel method of producing post‐concussive symptomologies, the lateral impact model (LIM). LIM is a closed‐head injury producing horizontal acceleration and rotation forces more typical in mTBIs. Adolescent male and female C57Bl/6 mice were administered repetitive mTBI (rmTBI) or sham injuries. To assess behavioural and physiological outcomes following rmTBI half of the mice were subjected to a behavioural test battery while the other half were used to profile neuroinflammatory dynamics. The behavioural battery began following the final rmTBI and was used to assess motor balance, locomotor activity, short‐term working memory, social tendencies, anxiety‐like, and depressive‐like symptomologies. The time profile of Pro‐ and anti‐inflammatory markers following rmTBI were measured with flow cytometry and ELISAs at one‐hour, six‐hours, 24‐hours, and one‐week post injury. We identified microglia and infiltrating monocyte populations and subclasses of CD3+ (T‐cells), Ly‐6G+ (polymorphonuclear leukocytes), CD19+ (B‐cells) and Ly‐6C+ (monocytes/macrophages) cells. Characterization of pro‐inflammatory and anti‐inflammatory phenotypes were based on relative expression of inflammatory nitric oxide synthase (iNOS) and the mannose receptor (CD206), respectively. Overall, the rmTBI mice displayed significant motor and affective post‐concussive symptomologies (p < .05). Furthermore, the flow cytometry data correlated quantitatively with previous immunohistochemical analyses in TBI models. To our knowledge, we are the first to develop a lateral impact model of mTBI in the mouse which provides a more translational model to study concussions and investigate molecular mechanisms with employment of genetically modified animals and other experimental methods not currently available in larger model systems.
Keywords: Mild traumatic brain injury, Inflammation, Behaviour, Microglia
ADAPTIVE IMMUNE RESPONSES IN TRAUMATIC BRAIN INJURY
1University of Cambridge, Division of Anaesthesia, Cambridge, United Kingdom
2University of Florida, Dept Emergency Medicine, Gainesville, USA
Keywords: autoantibodies, TBI, neurodegeneration
PHARMACOKINETICS OF COMBINATION THERAPY WITH RILUZOLE AND ETORICOXIB FOR TRAUMATIC BRAIN INJURY
University of Houston, Pharmacological and Pharmaceutical Sciences, HOUSTON, USA
Traumatic brain injury (TBI) has devastating secondary consequences, such as neuroinflammation and excitotoxicity. Few efficacious treatment possibilities make improving functional outcomes a major therapeutic aim. Neuroinflammation, activated by the production of prostaglandins, can be detrimental or beneficial and has been targeted for therapeutic regulation. Our goal is to investigate riluzole and etoricoxib as a novel combination therapy to simultaneously target excitotoxicity and neuroinflammation, respectfully, in TBI. We investigated the brain exposure, and pharmacokinetic plasma profiles over 24 hours after oral gavage administration of riluzole and etoricoxib at doses of 10 mg/kg, in co‐solvent formulation, with PEG 400, propylene glycol and glycerin (15:20:10% V/V). Three groups of male SD rats (N = 4 each) were dosed with the combination, single agent of riluzole, and etoricoxib, respectively. Brain samples were harvested at 24hr, and drugs in plasma and brain matrices were simultaneously quantified using a validated LC‐MS/MS assay. Comparisons between combination and single agent groups were performed on concentrations at each time and PK parameters derived from Phoenix WinNonlin® modeling, using Student's t‐test at p < 0.05. Etoricoxib plasma concentrations from combination formulation increased 217% and 773% at 9 and 24 hr post dose, respectively, and a significant enhancement in brain exposure with a 460% increase in tissue concentration at 24 hr, compared to those with etoricoxib alone dosing. The pharmacokinetic profile of etoricoxib revealed its potential enterohepatic cycling (EHC) due to the drug – drug interaction with riluzole that resulted in the potential favorable increased exposure. Riluzole combined with etoricoxib caused a decrease (p = 0.027) in the plasma concentration at 6 hr compared to dosing riluzole alone. These results characterized the drug – drug interactions between riluzole and etoricoxib that enhanced brain exposure of etoricoxib. In conclusion, this is the first pharmacokinetic evaluation in SD rats on the combination of riluzole, neuroprotective agent, and etoricoxib (selective COX‐2 inhibitor, NSAID) as novel therapeutic candidates for future treatment in TBI rat model.
Keywords: Neuroinflammation, Riluzole, Etoricoxib
TRAUMATIC BRAIN INJURY INDUCES CHANGES IN MICROBIAL DIVERSITY AND INTESTINAL PATHOLOGY
1University of Kentucky, SCoBIRC, Lexington, USA
2University of Kentucky, College of Medicine, Lexington, USA
3University of Kentucky, Department of Physiology, Lexington, USA
4University of Kentucky, Department of Internal Medicine ‐ Digestive Health, Lexington, USA
5University of Kentucky, Department of Immunology & Molecular Genetics, Lexington, USA
Traumatic brain injury (TBI) represents a major public health issue, affecting over 2.8 million annually in the US. While TBI triggers neurovascular and glial changes within the brain, it also induces systemic changes such as gastrointestinal dysfunction. Even in the absence of polytrauma, individuals that suffer a brain injury have an increased incidence of intestinal inflammation, ulceration, fecal incontinence and gastrointestinal‐related mortality. The gut microbiome is a key regulator of gastrointestinal health and findings suggest that alterations in the gut microbiota affect brain function. Under normal conditions, the gut microbiota act symbiotically with their host to promote proper immune and neurologic function. Dysbiosis, a condition in which the intestinal microbiota are disturbed, can both result from, and contribute to, gastrointestinal damage. Although brain health has been linked to overall gut health and gut microbes, the mechanisms underlying this connection are an area of intense investigation. TBI is associated with alterations to fecal microbial diversity but little is known about the time course of these changes and whether or how they influence secondary injury cascades in the brain. We hypothesize that TBI is sufficient to induce a prolonged dysbiosis and trigger intestinal damage. Conventionally raised male C57Bl/6J mice underwent a controlled cortical impact or sham injury and were euthanized 3‐ or 14‐days post injury (n = 3‐4/injury group). Histology and immunohistochemistry were used to assess intestinal pathology at 3‐ and 14‐days post injury. Fecal microbiome changes were assessed by analysis of 16S rRNA gene sequencing at 1‐ and 3‐days post injury. Analysis of sequencing data provides evidence of changes in diversity to the microbiome after TBI, and predicts changes in the microbiome's metabolic processes using PICRUSt.
Keywords: Microbiome, Neuroenteric Axis, Gut‐Brain Axis
ISOLATION AND DETECTION OF EXTRACELLULAR VESICLES FROM MOUSE SPINAL CORD TISSUE: IMPLICATIONS FOR NEUROTRAUMA
University of Maryland, Baltimore, Anesthesiology and Shock, Trauma and Anesthesiology Research Center (STAR), Baltimore, USA
Cells release extracellular vesicles (EVs) as a form of intercellular communication. EVs carry bioactive molecules whose composition can change during pathology. Previous work from our lab demonstrated an increase in a subset of plasma EVs 24h after mouse brain injury, which was associated with increased pro‐inflammatory microRNAs. To date, the majority of EV studies have been conducted in vitro after isolation of EVs from cell culture media or biological fluids like plasma. Direct support for the physiological role of EVs requires the ability to identify these structures at the tissue level. Here we provide the first evidence for EVs isolated from ex vivo mouse spinal cord tissue. We performed an enzymatic digestion of 1 cm spinal cord followed by differential centrifugation to remove cells and cellular debris. The remaining supernatant was overlaid onto a three‐step sucrose gradient (0.6M, 1.3M, 2.5M) to isolate EVs by density gradient ultracentrifugation. We found at least two populations of EVs differentiated by density that pelleted at 100,000g. High density EVs that equilibrated in 1.3M sucrose showed strong expression for classical EV markers including CD81, Flotillin‐1, and LAMP‐1 by Western Blot (WB). Low density EVs equilibrating in the 0.6M sucrose layer were also positive for CD81 by WB but had minimal expression of Flotillin‐1 and LAMP‐1. We further characterized these EV fractions at an individual particle level using the ExoView R100. This novel technology captures EVs onto surface‐coated antibody spots for tetraspanin proteins (e.g., CD9, CD81) that are highly enriched in EVs. With immunostaining after surface capture, we detected about twice as many CD81+ EVs in the high density fraction (1747 particles) compared to the low density fraction (874 particles) while CD9+ EV counts were only slightly different between fractions (high: 914 particles; low: 758 particles). Future work in our lab will apply this methodology to analyze how EVs contribute to local inflammatory and neurodegenerative processes after neurotrauma.
Keywords: Extracellular Vesicles, Exosomes, Spinal Cord Injury, Traumatic Brain Injury
CROSSTALK BETWEEN AUTOPHAGY AND NEUROINFLAMMATION FOLLOWING TRAUMATIC BRAIN INJURY
1University of Maryland, Baltimore, Anesthesiology, Baltimore, USA
2Trinity College, Dublin, Ireland
The autophagy‐lysosomal pathway has an important role in cellular homeostasis and serves a protective function against neurodegeneration. Recently autophagy has been also implicated in regulation of immune and inflammatory responses. Specifically, high levels of autophagy flux – the progress of substrates through autophagic compartments leading to their delivery and degradation in the lysosomes – are generally associated with anti‐inflammatory, and inhibition of flux with pro‐inflammatory phenotypes. To determine if autophagy may be involved in modulation of brain inflammation after TBI, we assessed the levels of autophagy in microglia and infiltrating macrophages following moderate controlled cortical impact (CCI) in C57Bl/6 mice. Consistent with a potential function in neuroinflammation, we observed accumulation of autophagosomes and inhibition of autophagy flux specifically in the activated microglia/macrophages. Our studies using transgenic Cx3Cr1‐GFP microglial and Ccr2‐RFP monocyte reporter mice also demonstrated that infiltrating macrophages are affected by the block of autophagy flux to a higher degree than activated resident microglia. Autophagy impairment in the activated cells of the microglia/macrophage lineage peaked at day 3 post‐CCI and persisted at least through day 7. At day 3 after CCI the cells with inhibited autophagy expressed both pro‐ and anti‐inflammatory polarization markers, indicating a mixed (transitional) inflammatory phenotype. Since the transitional cells are thought to preferentially switch to pro‐inflammatory fates, we hypothesized that inhibition of autophagy in these cells could promote their pro‐inflammatory polarization after TBI. Consistently, flow cytometry studies in TBI mice demonstrated increased expression of pro‐inflammatory marker and decreased phagocytic function in microglia and infiltrating monocytes with inhibited/low autophagy flux as compared to cells with higher autophagy flux. This was furthermore supported by our in vitro experiments demonstrating that inhibition of autophagy potentiates pro‐inflammatory activation induced by LPS treatment of macrophage and microglial cells and in vivo data showing impaired functional recovery in autophagy hypomorph Becn1+/‐ mice after injury.
Keywords: autophagy, cellular mechanisms, infiltrating monocytes, CCI
PROFILING TEMPORAL CHANGES IN IMMUNE CELL PHENOTYPES IN TRAUMATIC BRAIN INJURY
1UMN, Veterinary Population Medicine, Comparative and Molecular Biosciences, CVM, St. Paul, USA
2UMN, Neurosurgery, Medical School, Minneapolis, USA
Approximately 2.87 million people in the US had a traumatic brain injury (TBI) that led to hospitalization, ER visits, and death in 2014, an increase of 53% from 2006. About 60‐90% of injuries are mild, which increases the risk of developing Parkinson's Disease, Alzheimer Disease, and depression, potentially due to a chronic inflammatory process. Therefore, we designed an experiment to map the temporal changes in the immune cell phenotypes after mild TBI in 9 week old C57BL/6 mice. Injury was induced using a controlled cortical impactor centered over the primary and secondary motor cortices with 4m/s velocity, 1mm depth and 100ms dwell time. Mice were tested on spontaneous alternation Y maze, fear‐conditioning, and beam walk (n = 6) at 2, 6, 14, and 29 days post TBI to assess cognitive and motor deficits. Cohorts of mice were sacrificed at 3, 7, 15 and 30 days post TBI and neuroinflammation was characterized by flow cytometry (n = 6). The results showed a positive trend between the resolution of neuroinflammation and overt behavioral deficits. In the fear‐conditioning test, freezing time decreased 2 days after TBI, suggesting a decrease in memory retention which resolved at day 14. TBI also increased foot slips in test that requiring precise foot positioning which resolved at day 14. The total number of neutrophils and macrophages increased at day 3, with increased expression of CD86 and MHCII on macrophages. These cells returned to levels in the sham‐injured animals at day 14. The levels of inflammatory infiltrates seen at 3 days after mild injury were similar to that in animals subjected to moderate injury (6m/s; 1mm depth) at the same site. Funded in part by the Minnesota Spinal Cord and Traumatic Brain Injury Research Grant Program (Grant #128515), MN office of Higher Education, State of MN and the National Research Service Award T32 DA007097, NIDA, NIH
Keywords: Flow Cytometry, Cognitive Deficits, Behavioral Deficits, Neuroimmunology
HUMAN VS ANIMAL NEURAL/STEM PROGENITOR RESPONSE TO INFLAMMATORY CUES: IMPACT ON SUCCESSFUL TRANSLATION OF THERAPIES TO HUMANS
1University of Ottawa, Ottawa, Canada
2Ottawa Hospital, Ottawa, Canada
3Ottawa Hospital Research Institute, Ottawa, Canada
Keywords: translational, Human, porcine, glial scar, reactive astrogliosis, neurogenesis
IMPROVING PREDICTION OF POST‐TRAUMATIC DEPRESSION AT 12 MONTHS AFTER BRAIN INJURY USING RANDOM FOREST AND LOGISTIC REGRESSION
1University of Pittsburgh, Physical Medicine & Rehabilitation, Pittsburgh, USA
2University of Pittsburgh, Biostatistics, Pittsburgh, USA
3University of Pittsburgh, Safar Center, Pittsburgh, USA
4University of Pittsburgh, Clinical and Translational Science Institute, Pittsburgh, USA
Traumatic brain injury (TBI) includes the primary trauma and a secondary neuro‐metabolic crisis potentiated by factors such as inflammation. While a well‐controlled acute inflammatory response is vital to recovery, sustained inflammation may be harmful. Inflammatory biomarkers may be able to predict risk for adverse outcomes post‐TBI, as previous work suggests individuals with TBI and elevated acute (cerebrospinal fluid) and chronic (serum) inflammation are more likely to experience severe disability or death within six months post‐injury. This work assesses how inflammatory marker levels expressed in serum during the sub‐acute to chronic phase (2 weeks‐6 months) predict post‐traumatic depression (PTD) at 12 months post‐TBI. Predictive capacity was assessed using an inflammatory load score (ILS), which was created by summing the quartiles of inflammatory markers associated (p < 0.1) with PTD. We compared the prediction performance of logistic regression (LR) and random forest (RF) models in an imbalanced dataset with random missingness. We demonstrate that LR and RF models can have poor sensitivity despite high area under the curve (AUC) and discuss how sensitivity can be significantly improved by applying a down‐sampling scheme to these models. Our analyses, based on 10‐fold cross‐validation, showed high AUC on the test data (LR:70.68%, RF:87.97%), but the sensitivity was poor: only 14.29% (for both). The high accuracy measures (LR:65.38%, RF:76.92%) were mainly dominated by high specificities (LR:84.21%, RF:100%). We applied a down‐sampling scheme to achieve significantly better sensitivities (71.43% and 85.71%) at the cost of some loss in specificities (73.68% for both). Because PTD is a treatable secondary condition after TBI, remarkably improving detection rates for people at risk can be clinically beneficial in PTD prevention, screening or management algorithms for TBI medical providers. (Support: NIDILRR‐90DP0041, DODW81XWH‐071‐0701, CDC‐49‐CCR323155).
Keywords: Post‐traumatic depression, inflammatory markers, cytokines, logistic regression, random forest, prediction
ESTRONE EXPRESSION IN CEREBRAL SPINAL FLUID: LINKS TO NEUROINFLAMMATION, STEROIDOGENESIS, AND OUTCOME FOLLOWING CLINICAL TBI
1University of Pittsburgh, Physical Medicine and Rehabilitation, Pittsburgh, USA
2Icahn School of Medicine at Mount Sinai, Rehabilitation and Human Performance, New York, USA
3Seoul National University, Rehabilitation Medicine, Seoul, South Korea
4University of Pittsburgh, Safar Center for Resuscitation Research, Pittsburgh, USA
5University of Pittsburgh, Clinical and Translational Science Institute, Pittsburgh, USA
Sex hormone physiology following traumatic brain injury (TBI) is particularly compelling to study to reconcile apparent contradictions in hormone effects on clinical outcomes and in experimental animal models. We evaluated CSF estrone (E1) levels (n = 371 samples) in relationship to neuroinflammation, steroidogenesis, and outcome among n = 146 adults with severe TBI. Daily CSF E1 did not differ significantly by one‐month mortality, sex, or age. However, individuals with unfavorable outcomes (GOS score = 1,2,3) had significantly higher CSF E1 levels day 0‐3 post‐injury than those with favorable outcomes (GOS score = 4,5) (p = 0.014). We stratified individuals by day 0‐3 CSF E1 tertile to explore underlying differences in demographic, injury, inflammatory, and sex hormone factors. Best in 24‐hour Glasgow Coma Scale (GCS) score was more severe in the high E1 tertile (median = 6, IQR = 3‐7) than the low/middle E1 tertiles (median = 7, IQR = 6‐8). Interestingly, the middle tertile consisted of nearly 93% men. Day 0‐3 mean E1 levels increased with higher neurological burden scores (NBS), a sum of contusion, subdural (SDH) and subarachnoid (SAH) hemorrhage incidence. Also, day 0‐3 mean CSF interleukin (IL)‐5, IL‐6, IL‐8, IL‐10, soluble vascular cell adhesion molecule (sVCAM)‐1, soluble intracellular adhesion molecule (sICAM)‐1, and soluble (s)FAS levels all increased with higher E1 tertile. Mean tumor necrosis factor (TNF)‐alpha levels were significantly diminished in the low E1 tertile compared to middle and high E1 tertiles. Similarly, day 0‐3 mean CSF estradiol, progesterone, testosterone, and cortisol levels were significantly elevated with higher E1 tertile. These results suggest CSF E1 is a leading indicator of CNS hormone and inflammatory state post‐TBI and an early indicator of long‐term outcome. Support: NIDILRR‐90DP004, DOD‐W81XWH‐071‐0701, CDC‐R49‐CCR323155.
Keywords: Estrone, Sex Hormone Steroidogensis, Neuroinflammation, Neuroendocrine
CHARACTERIZING VARIABILITY AND LONGITUDINAL SYSTEMIC INFLAMMATION IN ACUTE HEMATOLOGIC AND RENAL ORGAN DYSFUNCTION FOLLOWING TBI
1University of Pittsburgh, Physical Medicine and Rehabilitation, Pittsburgh, USA
2University of Pittsburgh, Safar Center for Resuscitation Research, Pittsburgh, USA
3University of Pittsburgh, Clinical and Translational Science Institute, Pittsburgh, USA
Traumatic brain injury (TBI) is increasingly recognized for its deleterious impact and homeostatic disruption to non‐neurological systems and systemic functioning, which comes with additional morbidity burden. We assessed platelet and hematocrit data, along with creatinine data from medical records for adults with moderate‐to‐severe TBI to characterize variability in hematologic and renal organ system dysfunction, and their unique contributions, via inflammatory pathways, to long‐term outcome among individuals TBI survived out to six months post‐TBI (n = 173). We compared this information with serum inflammatory data from samples collected during acute (day 0‐5) (n = 484 samples) and chronic (2‐weeks‐6‐months) (n = 671 samples) periods post‐injury. Glasgow Outcome Scale (GOS) score was dichotomized as unfavorable (GOS score = 2,3) and favorable (4,5). Survivors with unfavorable GOS score exhibited significantly lower mean platelet and hematocrit with higher creatinine levels over the first 20 days post‐injury. Pearson correlation analyses suggested positive associations between mean levels of creatinine with interleukin (IL)‐12 (r = 0.57, p < 0.0001), as well as mean platelet levels with IL‐4 (r = 0.25, p = 0.0109) and IL‐7 (r = 0.43, p < 0.0001) (day 0‐5). Acute hematocrit and inflammatory relationships were less evident. Mean creatinine, platelet, and hematocrit levels up to 20 days post‐injury were significantly associated with IL‐2 and TNF‐alpha signaling measured and averaged over the first 6‐months post‐injury (p < 0.05 all comparisons). Interestingly, increased IL‐2 and TNF‐alpha signaling pathways were associated with unfavorable survivor‐based outcomes (p < 0.05 all comparisons). We investigated how commonalities among these inflammatory, hematologic and renal biomarker patterns impacted outcome using multivariate regression models, and the data show that early organ function is manifest chronically by dysfunctional acute TNF‐alpha and IL‐2 signaling. We propose this work provides insight on the utility of clinical laboratory measures of acute organ dysfunction in capturing later, down‐stream impacts of chronic inflammation on long‐term outcome. Support: UPP Foundation.
Keywords: Organ Dysfunction, Inflammation
THE INFLAMMATORY AND IMMUNOLOGIC IMPACT OF ACUTE CARE BETA‐BLOCKER ADMINISTRATION FOLLOWING CLINICAL TBI: A RETROSPECTIVE ANALYSIS
1University of Pittsburgh, Physical Medicine and Rehabilitation, Pittsburgh, USA
2University of Pittsburgh, School of Medicine, Pittsburgh, USA
3University of Pittsburgh, Safar Center for Resuscitation Research, Pittsburgh, USA
4University of Pittsburgh, Clinical and Translational Science Institute, Pittsburgh, USA
The traumatic brain injury (TBI) pathophysiology that drives delayed morbidity and mortality is at least partially grounded in the detrimental aspects of sympathetic nervous system (SNS) activation, aseptic inflammation, and subsequent immune‐depression. There is limited, yet compelling, evidence from human retrospective studies and experimental models that demonstrate the beneficial effects of beta‐blockers in mediating inflammation and limiting immune‐depression (expressed as neutrophil‐to‐lymphocyte ratio (NLR) reductions). We hypothesized that patients administered beta‐blockers during their acute hospitalization (first ten days post‐injury) will have lower NLRs than patients not receiving beta‐blockers during that timeframe. Eighty‐nine patients with moderate‐to‐severe closed head injury and with acute cerebral spinal fluid (CSF) inflammatory data (n = 313 samples) were examined. Individual medication data, absolute lymphocytes and neutrophils were abstracted from pharmacy orders and hematology laboratory results. Bivariate analyses compared demographic, clinical and injury‐related variables by beta‐blocker treatment group stratified by time‐to‐first administration. When stratifying time to first beta‐blocker administration at 10 days, group membership relationships to global outcome at six months were not evident; however, an observable separation in NLR levels appeared over days two through seven post‐injury. Compared to later beta‐blocker recipients, the early beta‐blocker recipient group (first 10 days) had lower mean NLR levels. This group also presented with acute CSF cytokine suppression of multiple inflammatory markers (p < 0.05 all comparisons) over the first five days post‐injury. These trends show the potential impact of beta‐blocker on overall immune response, neutrophil suppression, lymphocyte elevation, or both, after TBI. The findings described may also be relevant to clinical symptoms (e.g. dysautonomia, paroxysmal sympathetic hyperactivity) that drive clinical beta‐blocker use early after TBI.
Keywords: Beta‐blockers, Neutrophils, Lymphocytes, Sympathetic nervous system
TEMPORAL ACUTE SERUM ESTRADIOL AND TUMOR NECROSIS FACTOR‐α ASSOCIATIONS WITH MORTALITY AFTER SEVERE TRAUMATIC BRAIN INJURY
1University of Pittsburgh, PM&R, Pittsburgh, USA
2Icahn School of Medicine at Mount Sinai, Rehabilitation Medicine, New York, USA
3Emory University, Emergency Medicine, Atlanta, USA
4University of Utah, Reproductive Endocrinology, Salt Lake City, USA
5University of Pittsburgh, School of Nursing, Pittsburgh, USA
6University of Pittsburgh, Epidemiology, Pittsburgh, USA
Individuals with severe Traumatic Brain Injury (TBI) are at risk for systemic compromise and acute mortality. Tumor necrosis factor‐alpha (TNFα) is a mediator between systemic shock and an extra‐gonadal transcription factor for estradiol (E2) production, a prognostic marker of mortality after severe TBI. The study objectives were to test the hypothesis that acute serum concentrations of E2 and TNFα are interrelated and prognostic indicators of mortality after severe TBI. For n = 157 adults with severe TBI, serum samples were collected for the first five days' post‐injury. TNFα and E2 levels were averaged into 2 time epochs: first 72 hours (T1) and second 72 hours' post‐injury (T2). Cross‐lagged panel analysis showed significant acute interrelationships between E2 and TNFα. Cox proportional hazards multivariable regression models determined that increases in T1 E2 (HR = 1.82, 95% CI: 1.14, 2.89), but not T2 E2 (HR = 0.91, 95% CI: 0.56, 1.47), were associated with increased risk for mortality. Increases in T2 TNFα (HR = 2.55, 95% CI: 1.40, 4.64), and T1 TNFα (HR = 1.46, 95% CI: 0.99, 2.17) to a lesser degree, were associated with increased mortality risk. Individuals experiencing cardiovascular dysfunction had significantly higher 6‐month mortality rates compared to those without CV dysfunction (43.2% versus 17.3%). Overall, 20.7% of the association between T1 E2 and mortality and 21.9% of the association between T2 TNFα and mortality were explained by CV dysfunction as defined by the Sequential Organ Failure Assessment. This presented work demonstrates E2 and TNFα as systemic biomarkers indicative of systemic compromise, non‐neurologic organ dysfunction, and increased mortality risk after severe TBI.
Keywords: Estradiol, Tumor Necrosis Factor‐alpha, Mortality, Traumatic Brain Injury, Systemic Trauma Complex, Non‐neurological organ dysfunction
POST‐ACUTE SYSTEMIC INFLAMMATORY BIOMARKERS AND COGNITION AFTER TBI: A FOLLOW‐UP STUDY
1University of Pittsburgh, Department of PM&R, Pittsburgh, USA
2Mount Sinai, Icahn School of Medicine, NYC, USA
3University of Pittsburgh, School of Medicine, Pittsburgh, USA
4University of Pittsburgh, Center for Neuroscience, Pittsburgh, USA
5University of Pittsburgh, Safar Center for Resuscitation Research, Pittsburgh, USA
6University of Pittsburgh, Clinical and Translational Science Institute, Pittsburgh, USA
Cognitive impairment is a large contributor to traumatic brain injury (TBI) disability, yet few studies have examined the relationship between inflammation and cognition post‐TBI. Thus, we examined prospective relationships of post‐acute, serum inflammatory markers with cognitive performance at 6 and 12‐months for adults after moderate‐to‐severe TBI, using a weighted inflammatory load score (wILS) evaluating serum inflammation levels from 2 weeks to 3 months post‐injury. Subjects completed neuropsychological testing at 6 (n = 118) and 12 (n = 121) months post‐injury. Nine neuropsychological measures tested the domains of verbal fluency, memory, attention/processing speed, and executive function. Overall composite scores were created as an average of normalized mean T‐scores for each cognitive domain. Domain‐specific and overall cognition wILS were generated. wILS values were generated using a 2‐step process wherein associations between standardized serum cytokine levels, and composite scores were assessed using multivariable linear regression. Standardized markers (p < 0.10) were then multiplied by regression‐derived β‐values and summed to generate each wILS. Multivariable linear regression included co‐variate adjusted associations between wILS and composite scores. wILS captured 8.43% and 10.36% additional variance for overall composite score at 6 and 12 months. For each 1‐unit increase in wILS, overall composite T‐scores increased by β = 1.029 (p = 0.0005) and β = 0.903 (p = <.0001) at 6 and 12 months. Domain‐specific wILS discriminated performance on domain‐specific composite scores including memory, verbal fluency, attention/processing speed, and executive function. Results show post‐acute inflammatory profiles are associated with cognitive performance at 6 and 12‐months post‐TBI. Compared to our previous unweighted methods, this wILS utilizes fewer markers to explain greater variance in composite scores. Identifying inflammatory biomarker tools sensitive to cognitive performance post‐TBI may support future intervention and prognostication studies. Support: DOD‐W81XWH‐071‐0701, CDC‐R49‐CCR‐323155‐03, NIDILRR‐90DP0041
Keywords: Cognition, Chronic Inflammation, TBI, Memory, Executive Function, Attention
INTRANASAL INSULIN REDUCES INFLAMMATION AFTER TBI: POTENTIAL MECHANISMS
USUHS/US Army, Bethesda, USA
Traumatic brain injury (TBI) affects approximately 1.5 million Americans annually. Injured tissue from TBI results from direct injury and the ensuing fluctuations in metabolic processes and immune response. To date, there are no treatments available to address these changes in cellular metabolism or immune response. Administration of insulin through the nose (intranasal) allows for insulin to be absorbed directly into the brain, increases glucose uptake, and improves memory, while avoiding negative effects on blood glucose. Our lab has shown that this treatment significantly increased memory and decreased edema volume within the hippocampus in rats after a moderate TBI. The current study evaluates the potential mechanism of intranasal insulin after TBI by examining cellular and molecular changes from 6 hours through 10 days post‐injury (DPI). Adult male rats received a controlled cortical impact (CCI) TBI, followed by daily intranasal treatment with 6 international units (IU) insulin or vehicle (saline) that began at 4 hours post injury and continued daily through 14 days DPI. In the cortex, there was a robust increase in phosphorylation of both AKT and MEK that corresponded with the dramatic rise in microglia accumulation around the area of injury at 4 DPI. Intranasal insulin administration resulted in a significantly higher increase in the phosphorylation of MEK within the cortex at 4 and 10 DPI in comparison to the saline‐treated group. Within the hippocampus, there were significant fluctuations in both AKT and MEK phosphorylation with a general trend of decrease in AKT and rise in MEK over time, but show no effect of treatment at any timepoint. Intranasal insulin administration did reduce activated microglia at 6hr and 24hr post injury and reduced tissue necrosis factor alpha (TNFa – a pro‐inflammatory cytokine implicated in insulin resistance) at 24hrs in the hippocampus. These data suggest that intranasal insulin is affecting the hippocampus by decreasing inflammation at acute timepoints by decreasing activated microglia and inflammatory cytokines, In the cortex, alterations in responses may be due to effects on the MAPK pathway.
Keywords: Intranasal insulin, TBI, signaling, cytokines
EFFECTS OF CHRONIC SYSTEMIC VERSUS CENTRAL INFLAMMATORY CHALLENGE ON MOTIVATION IN RATS
West Virginia University, Psychology, Morgantown, USA
Neuroinflammation is highly correlated with numerous neurological and psychiatric disorders and chronically elevated after traumatic brain injury (TBI). However, it is unclear whether TBI‐induced neuroinflammation causes psychiatric dysfunction. The aim of this study was to selectively model chronic neuroinflammation in the absence of other confounding TBI pathology. Lipopolysaccharide (LPS) is a component of gram‐negative bacteria and was used to activate microglia, inducing activity of pro‐inflammatory cytokines. Rats were trained on a progressive ratio schedule, an operant task used to assess motivation as a measure of depressive‐like behavior. In this task, a lever is extended and presses on the lever are reinforced by providing a sucrose pellet. With each pellet received, the number of presses for reinforcement is increased. The sessions were 60 minutes long or terminated after 5 minutes of no responding. Animals were trained to a stable baseline (∼30 sessions) then an acute or chronic dose of LPS was administered one of three ways. Acute doses were intraperitoneal injection of LPS at 2, 1, or 0.5 mg/kg, whereas chronic doses were subcutaneous (0.71 mg/kg/day LPS or saline) or intracerebroventricular to the lateral ventricle (1.5 μg/day LPS or saline) via osmotic mini‐pumps for 14 days. Behavior was evaluated on the progressive ratio after/during the LPS exposure. The acute systemic doses of 1 and 2 mg/kg of LPS decreased motivation. The chronic peripheral dose of LPS caused a transient drop in motivation, but rapidly recovered, suggesting that central administration will yield larger effects through bypassing peripheral adaptive immunity. While chronic LPS led to increased depressive‐like behaviors, further investigation to the relationship between neuroinflammation and depression is needed and may give insight into the prevalence of psychiatric disease following brain injury.
Keywords: Lipopolysaccharide, Rat, Motivation, Traumatic brain injury
B10 Informatics
TRANSCRIPTOMIC ANALYSIS OF MOUSE BRAIN REGIONS AFTER TBI INDICATES CANDESARTAN TREATMENT ALTERS NOVEL MOLECULAR PATHWAYS
1Uniformed Services University of the Health Sciences, Department of Pharmacology, Bethesda, USA
2Henry M. Jackson Foundation for the Advancement of Military Medicine, Bethesda, USA
3Uniformed Services University of the Health Sciences, Department of Anatomy, Physiology & Genetics, Bethesda, USA
4Collaborative Health Initiative Research Program, The American Genome Center, Bethesda, USA
We have previously shown that the angiotensin receptor blocker candesartan, improves functional recovery, and reduces pathology in mice after controlled cortical impact injury (CCI). Although candesartan blocks signaling through the AT1 angiotensin receptor, the molecular mechanisms through which it is beneficial to recovery, are not understood. In order to identify changes in expression of potential targets of candesartan's action we performed transcriptome profiling by mRNA‐seq on RNA isolated from three different brain regions, the hippocampus, thalamus, and hypothalamus in mice after candesartan or vehicle treatment, with or without CCI injury, 3 and 29 days after injury. Individual groups were compared to sham mice and differentially expressed genes (DEGs) were identified with a false discovery rate of 0.05. The largest differences between groups were found in the hippocampus at 3DPI. All groups had fewer DEGs by 29DPI. While direct comparison between drug and vehicle treatment after CCI did not show significant DEGs, there were significantly fewer inflammatory genes induced after candesartan treatment at both 3DPI and 29DPI. Gene ontology analysis indicated that candesartan treatment alone showed significant reductions in transcriptome signatures enriched in Wnt‐protein binding, oxidoreductase activity, cellular adhesion, and transcellular transport, mainly in the hippocampus. At 29DPI, candesartan showed regulation of possible novel mediators including the down‐regulation of the lncRNA Malat1 that has been implicated in chronic inflammatory processes. These data suggest that candesartan mediates its beneficial effects after CCI through pathways associated with decreased expression in acute and chronic inflammatory genes. Other targets of candesartan action include genes encoding cell adhesion and solute carriers suggesting significant activity in the cerebrovasculature.
Keywords: Transcriptomic Analysis, Molecular Mechanisms, Angiotensin System, TBI Treatment Mechanisms
DISSECTING MOLECULAR MECHANISM AND THERAPEUTIC IMPACT OF REMOTE ISCHEMIC CONDITIONING IN A MOUSE MODEL OF DIFFUSE TRAUMATIC BRAIN
1University of Arizona COM ‐ Phoenix, Child Health, Phoenix, USA
2BARROW Neurological Institute at Phoenix Children's Hospital, Phoenix, USA
3Translational Genomics Research Institute, Collaborative Center for Translational Mass Spectrometry, Phoenix, USA
4Phoenix VA Health Care System, Phoenix, USA
Traumatic brain injury (TBI) can increase the risk and accelerate development of multiple neurodegenerative diseases. Diffuse TBI can go undiagnosed or misdiagnosed due to lack of available, reliable diagnostic or therapeutic biological markers required for precision medicine. Furthermore, interventions such as remote ischemic conditioning (RIC; transient restriction of blood flow to a limb or non‐vital organ) that can reduce the expression of these biomarkers may be beneficial for chronic outcomes. This study sought to determine interactions between diffuse TBI and RIC on proteins and metabolites in blood. Male C57BL/6 mice were subjected to midline fluid percussion injury. Fifteen minutes following recovery of righting reflex, mice were randomly assigned to a treatment cohort (TBI RIC, TBI no‐RIC, Sham RIC, Sham no‐RIC). Plasma was collected 24hrs after RIC procedure. During proteomic discovery phase, 29 proteins were differentially expressed between TBI and RIC treated groups. Four of these proteins were chosen for validation. Discovery predicted RIC and TBI main effects on the expression of selenium‐binding protein 1 (SBP1), complement factor B (CFB), superoxide dismutase (SOD1), and heat shock cognate (HSPA8). During validation, SOD1 was expressed significantly more in TBI no‐RIC mice compared to sham groups and TBI RIC mice (RIC: F(1,12) = 5.522, p = 0.0367; interaction: F(1,12) = 14.40, p = 0.0026). There was a RIC effect in SBP1 and CFB (SBP1: F(1,12) 5.697, p = 0.0343; CFB: F(1,12) = 6.245, p = 0.0266). These data expose potential new biomarkers for TBI and mechanisms for RIC treatment. Further studies will determine if RIC can reduce TBI pathophysiology through associated cellular mechanisms. Funding: NIH‐R21‐NS096515 and T32‐AG044402
Keywords: Proteomics, Metabolomics, Remote ischemic conditioning, Midline fluid percussion injury
DATA SHARING INFRASTRUCTURES FOR SPINAL CORD INJURY: ODC‐SCI.ORG AND BEYOND
1UCSF, San Francisco, USA
2UCI, Irvine, USA
3Univ of Miami, Miami, USA
4NIH, Bethesda, USA
5Univ of Louisville, Louisville, USA
6OSU, Columbus, USA
7iCORD, Vancouver, Canada
8UCSD, San Diego, USA
9Univ of Alberta, Edmonton, Canada
10Univ of Minnesota, Minneapolis, USA
11SFVAMC, San Francisco, USA
The complexity of spinal cord injury has limited translational bench‐to‐bedside results, and the traditional publishing model of summarizing SCI complexity with sparse univariate measures (t‐tests, ANOVA, correlations) has contributed to the reproducibility crisis. The variety of data collected on a single SCI subject represent a ‘big‐data’ problem, calling for modern data science solutions beyond traditional scientific publication. With the advent of big‐data analytics, we now have the opportunity to leverage the multidimensional nature of SCI to drive scientific insights. To seize this opportunity, managing and sharing SCI data is essential. We recently developed the Open Data Commons for Spinal Cord Injury (odc‐sci.org) to facilitate data‐sharing within/between labs. ODC‐SCI currently hosts 49 labs, with 152 unique datasets, representing a broad cross‐section of preclinical SCI data. The goal of odc‐sci.org is to make SCI data FAIR (Findable‐Accessible‐Interoperable‐Reusable) and provide mechanisms for data‐management and open data citation. However, there are instances in which SCI researchers collect sensitive data that needs to remain private, such as data sets designed to meet regulatory approval (FDA), sensitive intellectual property, non‐human primate studies, among others. We have addressed this need by developing a Private Data Commons for SCI (PDC‐SCI). This private infrastructure is ideal for multi‐lab transdisciplinary studies that require well‐organized, scalable data commons for rapid data‐sharing within a closed, distributed team. We present features of PDC‐SCI through the use‐case of the VA Gordon Mansfield SCI Consortium. Support: CHN Foundation, WfL, ISRT, Rick Hansen Institute, INCF, UCSF‐BASIC, University of Alberta, NIH(NS088475, NS106899, MH116156), VA(I01RX002245‐01, I01RX002787).
Keywords: Data Sharing, SCI, Informatics, Big Data
IMPACT OF ALCOHOL ABUSE HISTORY ON SUBJECT RETENTION IN TBI CLINICAL RESEARCH: A TRACK‐TBI STUDY
University of Pittsburgh, Neurological Surgery, Pittsburgh, USA
Keywords: alcohol, AUDIT‐C, Retention, screening
B11 Microglia
TIME‐DEPENDENT CHANGES IN MICROGLIA TRANSCRIPTIONAL NETWORKS FOLLOWING TRAUMATIC BRAIN INJURY
1Brigham and Women's Hospital, Neurology, Boston, USA
2School of Basic Medical Sciences, Fudan University, Department of Anatomy, Histology and Embryology, Shanghai, China
3Massachusetts General Hospital, Department of Pediatrics, Boston, USA
4Massachusetts General Hospital, Center for Immunology & Inflammatory Diseases, Boston, USA
5Tufts University, Department of Biomedical Engineering, Medford, USA
Microglia play a critical role in neuroinflammation and their persistent activation may contribute to long‐term functional deficits. However, to our knowledge, no study has characterized temporal expression patterns, including the chronic period, of microglia specific inflammatory genes in a preclinical TBI model.
Keywords: Traumatic brain injury, Microglia, Transcriptome, Neurodegeneration, Neuroinflammation
CHARACTERIZATION OF PRIMARY RAT MICROGLIA FOLLOWING EXPOSURE TO STRETCH‐INJURY
Uniformed Service University, GEO, Bethesda, USA
Traumatic brain injury (TBI) is a major public health concern with 1.7 million case report annual. Primary forces acting upon the cranium lead to immediate and irreversible cellular damage and dysfunction, resulting in downstream pathophysiological processes. Neuroinflammation is a prevalent pathology observed following TBI and can last for decades following a single insult. Microglia play an integral role in initiating and mediating the inflammatory cascade following TBI by interacting with soluble factors released from cells following the initial injury. In vitro models of neurotrauma demonstrate that microglia become activated when exposed to media from stretch‐injured astrocytes. However, to date, the effect of this same mechanical strain on microglia are unknown. To address this gap in knowledge we characterized the effect of a 5psi stretch‐injury on post‐natal day two rat microglia in an in vitro model of neurotrauma using the Cell Injury Controller II (CIC II). We assessed viability and reactivity using media assays for lactate dehydrogenase (LDH) and nitric oxide (NO), respectively. Using these outcome measures we conducted a time course study at one, six, twelve, eighteen, twenty‐four, forty‐eight, and seventy‐two hours post stretch‐injury. Results from the LDH assay revealed no significant difference between the stretch‐injury and control group at any time point. Interestingly, when compared to controls, the stretch‐injury group displayed a significance decrease of NO release at twelve, eighteen, and forty‐hours following injury. To address these findings, we characterized integrin expression, oxidative stress, polarization markers, and metabolic changes at twelve hours post‐injury. We found no significant changes in oxidative stress, metabolism, or markers of polarization. We did observe an increase in the beta‐1 integrin in the stretch‐injured group compared to controls. Vinculin was increased in cells cultured on Pronectin coated plates, suggesting the formation of focal adhesion complexes through integrin extracellular matrix (ECM) binding. The information gathered from this characterization study will contribute to the mechanistic understanding of microglia function following TBI and potentially provide sites for therapeutic intervention.
Keywords: In vitro, Stretch‐injury
A METABOTROPIC GLUTAMATE RECEPTOR 4 POSITIVE ALLOSTERIC MODULATOR, ADX88178, ATTENUATES MICROGLIAL ACTIVATION IN VITRO
1University of Maryland School of Medicine, Department of Anesthesiology, Baltimore, USA
2University of Maryland School of Medicine, Shock, Trauma and Anesthesiology Research (STAR) Center, Baltimore, USA
Microglial activation is a major hallmark of neuroinflammation following brain trauma. Major efforts have focused on developing strategies to inhibit microglial activation and attenuate the release of pro‐inflammatory cytokines following brain injury. Metabotropic glutamate receptors (mGluRs) are expressed on neurons and glial cells. Prior research on mGluRs relating to neuroinflammation have focused on group I and II receptors, with less focus on group III. Similarity in the ligand binding domain for group III mGluRs has proved challenging in developing orthosteric agonists. In contrast, positive allosteric modulators (PAMs) for these receptors may provide a better selectivity. Limited prior research has suggested that mGluR4 agonists may limit microglial activation in vitro. ADX88178 is a potent, orally bioavailable mGluR4 PAM that can cross the blood brain barrier. We examined the effects of ADX88178 in vitro‐ using BV2 microglia cells and primary microglia. We showed that ADX88178 downregulated expression of pro‐inflammatory mediators TNF‐α, IL‐1β, CCL‐2, and miR‐155 after exposure to LPS. Unlike purported mGluR4 PAMs that showed attenuation of microglial activation, the mGluR4 orthosteric agonist L‐AP4 did not. Additionally, we administered ADX88178 orally after controlled cortical impact injury in adult male C57BL/6 mice to examine acute secondary injury processes but did not observe changes in release of pro‐inflammatory cytokines. This may have reflected dosing or timing issues. It has been shown that mGluR PAMs can dimerize with other mGluR groups or with adenosine receptors (A2a and A3). We tested the effects of A2a receptor agonist or A3 receptor antagonist in combination with ADX88178, but we did not observe reversal in the neuroprotective actions of mGluR4 PAM. These studies demonstrate that certain mGluR4 PAMs can reduce pro‐inflammatory effects of LPS activated microglial cells, but further investigation is needed to elucidate the specificity or mechanism of action for these compounds.
Keywords: mGluR
PEDIATRIC TRAUMATIC BRAIN INJURY CAUSES LONG LASTING ADULT HIPPOCAMPAL NEUROGENESIS IMPAIRMENT AND COGNITIVE DEFICITS
1University of Michigan‐Dearborn, Natural Sciences, Dearborn, USA
2Johns Hopkins School of Medicine, ACCM, Baltimore, USA
Young children who have sustained severe traumatic brain injury (TBI) can suffer from debilitating neurocognitive deficits. Impairment of adult hippocampal neurogenesis is associated with cognitive deficits and depression. The hippocampus is particularly vulnerable after TBI, and it can be damaged even when it is not directly injured. Very few studies have investigated adult hippocampal neurogenesis after pediatric TBI. Here we evaluated the long‐term cognition and adult hippocampal neurogenesis in a rabbit model of pediatric TBI. On postnatal day 5‐7 (P5‐7), New Zealand white rabbits from the same litter were randomized into naïve, sham (craniotomy alone) and TBI (controlled cortical impact). Bromodeoxyuridine (BrdU, 50 mg/kg, ip) was administered at one‐month post‐injury, once/daily for five consecutive days. Novel object recognition (NOR) and T‐maze spontaneous alternation tests were performed at 2 months post‐injury to measure the cognitive functions. The animals were euthanized after behavioral tests at 3 months of age to evaluate hippocampal adult neurogenesis and microglial activation. We found that 1) Pediatric TBI significantly impaired cognitive functions at 2 months post‐injury; 2) The survival rate of adult‐born neurons at both the ipsilateral and contralateral hippocampus significantly decreased in the TBI kits at 3 months post‐injury. 3) TBI induced aberrant migration of the adult‐born neurons at 3 months post‐injury. 4) TBI induced abnormal microglial morphology at 3 months post‐injury. In conclusion, pediatric TBI causes prolonged dysregulation of the adult hippocampal neurogenesis through young adulthood, which might be, at least partly, responsible for the cognitive deficits. Protection of adult hippocampal neurogenesis at the chronic phase of injury may potentially improve outcomes and functionality.
Keywords: hippocampus, Pediatric, controlled cortical impact, rabbit
RESTORATIVE MICROGLIA‐OLIGODENDROCYTE INTERACTIONS IN POST‐TBI REMYELINATION
1University of Pittsburgh, Department of Neurology, Pittsburgh, USA
2Univeriity of Pittsburgh, Pittsburgh Institute for Neurodegenerative Disorders, Pittsburgh, USA
3University of Pittsburgh, Department of Neurosurgery, Pittsburgh, USA
4Veterans Affairs Pittsburgh Health Care System, Pittsburgh, USA
Traumatic brain injury (TBI) patients often develop long‐lasting traumatic axonal injury, which contribute to motor‐sensory and cognitive functional deficits. Upon brain injury, microglia are rapidly activated and cause inflammatory responses, leading to white matter demyelination. Meanwhile, alternatively activated microglia with adaptive functions release restorative cytokines/growth factors that promote remyelination. It remains incompletely understood how microglia communicate with oligodendrocytes during white matter tissue repair after TBI. Microglial Na+/H+ exchanger (NHE1) mediates H+ efflux that maintains pHi homeostasis and is required for microglial activation. In this study, we investigated roles of microglial NHE1 in TBI‐induced white matter injury and remyelination. Selective deletion of microglial Nhe1 in Cx3cr1‐CreER;Nhe1flox/flox mice (Nhe1 KO mice) was induced by tamoxifen (Tam). Tam‐injected Cx3cr1‐CreER mice were used as control (Con). TBI was induced by controlled cortical impact. While the Con and Nhe1 KO sham‐control mice exhibited similar APC+ mature oligodendrocytes in corpus callosum (CC) and external capsule (EC), the Nhe1 KO sham mice displayed 20% increase in the CC thickness than the Con sham mice (p < 0.05). TBI caused a significant reduction in APC+ counts in the Con mice but not in the Nhe1 KO mice at 24 h after TBI. These Nhe1 KO mice concurrently exhibited increased CC thickness and higher NG2+Olig2+ oligodendrocyte precursor counts than the Con mice (p < 0.05). Post‐TBI administration of NHE1 protein inhibitor HOE642 accelerated motor‐sensory and cognitive functional recovery, as well as preserved white matter integrity. These studies indicate that microglial NHE1 is important for microglia‐mediated inflammation, and blocking microglial NHE1 skews the microglia‐oligodendrocyte interactions towards restorative functions and stimulates oligodendrogenesis and remyelination. NHE1 protein emerges as a potential therapeutic target for white matter repair after TBI.
Keywords: microglia, oligodendrocytes, traumatic brain injury, Na+/H+ exchanger‐1
THE ROLE OF INOS DERIVED NO IN MACROPHAGE ACCUMULATION AFTER TBI
1Dept. Critical Care Medicine, Safar Center, Children's Neuroscience Institute, University of Pittsburgh, Pittsburgh, USA
2Dept. Environmental and Occupational Health, Center for Free Radical and Antioxidant Health, University of Pittsburgh, Pittsburgh, USA
3Dept. Developmental Biology, University of Pittsburgh, Pittsburgh, USA
Support: NS076511, NS061817
Keywords: Macrophage, Microglia, Nitric Oxide
THE ROLE OF CANNABINOID 2 RECEPTOR IN MODULATING MICROGLIA ACTIVATION AFTER A TRAUMATIC BRAIN INJURY
1William Paterson University, Biology, Wayne, USA
2NIH, NIA, Baltimorre, USA
Traumatic brain injury (TBI) occurs when a sudden trauma is applied to the head and causes damage to the brain. TBI can result from a multitude of events including most commonly from sports injuries, vehicle collisions, violence, falls, and war. It is estimated that there are 1.4 million cases of TBIs in the USA every year. Injury can result in permanent disabilities and in severe cases it can be fatal. Symptoms after a TBI can be mild, moderate and severe depending on the extent of brain damage as well as location. Long‐term behavioral effects can be characterized including depression, anti‐social behavior, and fear/anxiety. Additionally, TBI injuries have shown symptoms that are closely related to Parkinson's and Alzheimer's like‐symptoms. Currently, there are no specific treatments for a TBI injury. TBI occurs in two phases, the primary injury (physical aspect of the injury) and the secondary injury which consists of cellular process activated hours, days, and months after the initial injury. Neuroinflammation arising during the secondary injury can lead to neuronal death and involves the activation of microglia. The Endocannabinoid system (ECS) consist of two major receptors CB1 and CB2, including the endocannabinoids that activate these receptors and the enzymes involved in their synthesis and degradation. Previously published in vitro data indicates that activation of CB2 receptors in microglia decreased the production of pro‐inflammatory factors; thus expression of CB2 receptor in microglia may play a role in the modulation of the immune response. This research evaluated the role of microglia activation after TBI by using CB2 receptor knockout mice (Cx3‐Cnr2) which would not express the characteristic neuroprotective effects on local neural circuits. The mechanism of action in which this occurs is not fully understood. We found that Cx3‐Cnr2 mice show a difference compared to control mice when evaluating anxiety and fear behavior using a multitude of standard behavioral tests.
Keywords: fear, anxiety, endocannabinoids
B12 Neurodegeneration
INJURY THRESHOLDS: STRUCTURAL ALTERATIONS TO CULTURED HIPPOCAMPAL NEURONS FOLLOWING INCREASING STRAINS
1Army Research Laboratory, WMRD, Aberdeen, USA
2Bennett Aerospace Inc., Cary, NC
3Boston University, Boston, MA
Traumatic brain injury (TBI) occurs when an external, mechanical force causes brain distortion beyond a certain tolerance. To design the best protection to prevent TBI, it is important to understand these tolerances. In vitro models can investigate individual neuronal responses to mechanical loading. Cultures of primary pyramidal neurons and astrocytes were grown on BioFlex® plates and stretched at different strains (0%, 3%, 12%, 20%, 28% or 37%) using the Cell Injury Controller II. Phase‐contrast images were collected prior to stretch and at several time points after (1min, 4hrs, and 24hrs). Neuronal alterations were assessed using several methods: microtubule associated protein 2 (MAP2) was used to identify focal, neuritic bead‐like swellings; a fragmentation index provided a neurodegeneration measure; and Sholl analysis described neuritic arborization. The beading score took the volume‐weighted sum of the radii of axonal swellings, normalized by the length of said axon. The fragmentation index was the dystrophic axonal area over the total thresholded axonal area. And the arborization was characterized by the number of intersections of neurites and their branches at prescribed distances from the soma, the radial distance from the soma at which the maximum number of neurites/branches intersected a circle with that radius, and a regression coefficient describing the change in density of neurites as a function of distance from the soma. The beading score and fragmentation index measures did not demonstrate a statistically significant difference between the strain levels or time points. However, quantification of the arborization revealed that the number of maximum intersections significantly decreased, while the regression coefficient showed a significant immediate increase in rate of decay following 28% and 37% strains compared to sham. The Sholl analysis was the most sensitive measure evaluated for describing morphological alterations following injury. Finally, this study identified a threshold of structural injury to be between 20% and 28% strain using the morphological metrics described.
Keywords: Sholl, Cell Culture, Strain, TBI, MAP2, Fragmentation Index
EXPERIMENTAL SPINAL CORD INJURY REDUCES MECHANOSENSITIVITY OF VAGAL AFFERENTS
1Gettysburg College, Health Sciences, Gettysburg, USA
2Penn State College of Medicine, Neural and Behavioral Sciences, Hershey, USA
The upper gastrointestinal (GI) system relies exclusively on the vagus nerve for basic coordinated reflex actions necessary for digestion. The afferent (sensory) fibers within the gastric vagus transmit mechanical and chemical stimuli. Mechanosensitive fibers are located predominantly in the stomach and presumably regulate satiety and gastric motility through volumetric stimuli. The proximal segment of the duodenum and distal small intestine transmit chemosensory stimuli to provoke nutritive satiety and altered motility. We have previously demonstrated that gastric reflexes to GI peptides associated with “nutritive” satiety (e.g., cholecystokinin [CCK] and ghrelin) are diminished following T3‐SCI and these signals are attenuated at the initial segments of the vagal afferents. The mechanism of chemosensory dysfunction and the universality of this dysfunction to volumetric stimuli remains obscure. We hypothesize that T3‐SCI causes vagal afferent hyposensitivity to mechanical stimuli originating at the stomach. Male Wistar rats received a contusion T3‐SCI or laminectomy at 3 days or 3 weeks prior to experimentation. Rats were anesthetized then vagal afferents were isolated and attached to recording electrodes. The stomach was subjected to graded mechanical stimuli with von Frey Hairs. In a separate group, gastric vagal afferents were retrogradely traced with DiI, and nodose ganglia (NG) were dissociated to single cells. The expression of CCK‐A and TRPV1 receptors in gastric‐projecting afferents were then analyzed with immunocytochemistry (ICC) paired with confocal imaging. Vagal afferent mechanical responses were reduced in T3‐SCI rats at 3 days and 3 weeks, suggesting a desensitization of gastric mucosa mechanoreceptors. NG chemoreceptors CCK‐A and TRPV1 revealed alterations in immunoreactivity. There were no significant changes in CCK‐A from 3 days to 3 weeks in T3‐SCI; TRPV1 levels significantly increased from 3 days to 3 weeks in T3‐SCI. These results suggest that SCI‐induced Gl dysfunction is partially due to hypoexcitable vagal mechanosensory afferents and increased expression levels of inflammatory‐induced TRPV1 receptors. Support: NS049177 & Gettysburg College Internal Award
Keywords: Gastric emptying, gastrointestinal motility, vago‐vagal reflexes, stomach, TRPV1
MILD TRAUMATIC BRAIN INJURY IN OLDER ADULTS AND ALZHEIMER'S DISEASE SHARE PATTERNS OF WHITE MATTER DEGENERATION
1University of Southern California, Leonard Davis School of Gerontology, Los Angeles, USA
2University of California Los Angeles, Semel Institute for Neuroscience and Behavior, Los Angeles, USA
White matter (WM) alterations associated with mild traumatic brain injury (mTBI) and Alzheimer's disease (AD) have been well described. For example, studies utilizing diffusion tensor imaging (DTI) have found that, compared to healthy control (HC) participants, both conditions are associated with a decrease in the WM fractional anisotropy (FA) of the corpus callosum and cingulum bundle. However, no direct comparisons have been made yet between the patterns of WM degeneration due to mTBI vs. AD. Recent interest in the possibility that mTBI is a risk factor for AD has motivated us to investigate whether these conditions share patterns of WM neurodegeneration. DTI volumes acquired at 3 T and tract‐based spatial statistics were utilized to investigate WM FA differences between age‐ and sex‐matched older‐adults: 33 chronic mTBI patients, 67 AD patients and 81 HC participants. The mTBI group underwent a scan at ∼6 months post‐injury. Eddy‐current correction, tensor estimation and FA map generation were completed using FSL software. Confirming our expectations, there was a significant mean FA difference between the mTBI and HC groups, as well as between the AD and HC groups, with differences observed throughout the entire brain (p < 0.01). The WM FA comparison of the mTBI and AD group was completed using two‐one‐sided t tests (TOSTs) of statistical equivalence, utilizing a null hypothesis specified by Cohen's d < 0.3. The WM FA means of the mTBI and AD groups were found to be statistically equivalent across the WM skeleton (p < 0.05, corrected). In conclusion, we suggest that, over 6 months post‐injury, mTBI may lead to FA alteration patterns which are statistically very similar to those found in AD patients. Future research should seek to elucidate the relationship between mTBI, AD and WM degeneration.
Keywords: mTBI, Alzheimer's Disease, white matter degeneration, brain imaging
THE EFFECTS OF CEREBRAL MICROHEMORRHAGES ON WHITE MATTER CONNECTIVITY AND AGING IN MILD TRAUMATIC BRAIN INJURY
Di Fan1, Nikhil N. Chaudhari1, Kenneth A. Rostowsky1, Maria Calvillo1, Sean K. Lee1, Nahian F. Chowdhury1, Fan Zhang2, Lauren J. O'Donnell2,
1University of Southern California, Leonard Davis School of Gerontology, Los Angeles, USA
2Harvard Medical School, Laboratory of Mathematics in Imaging, Boston, USA
Mild traumatic brain injury (mTBI) is frequently associated with the presence of cerebral microbleeds (CMBs) in the brain parenchyma. CMBs may lead to long‐term white matter (WM) alterations and neurocognitive deficits, both of which may be further exacerbated in older adults due to neurobiological brain changes related to senescence. In this study we aim to 1) report the efficacy of a new CMB identification algorithm, 2) assess longitudinal WM fractional anisotropy (FA) differences in mTBI, and 3) evaluate the statistical relationship between CMB presence and changes in the FA of the WM in areas neighboring CMBs. Participants included 25 older adults with a history of mTBI who were assessed within 6‐8 months post‐injury using T1‐ and T2‐ weighted magnetic resonance imaging, gradient recalled echo/susceptibility‐weighted imaging (SWI) and diffusion tensor imaging (DTI) acquired at 3T. Preprocessing was completed using FMRIB Software Library. CMB identification was achieved automatically from SWI, through the implementation of a gradient‐based edge detection method. WM connectivity streamlines were segmented and clustered using a comprehensive DTI atlas, after which their prototypes were identified. A correlation coefficient was then calculated between (A) the WM FA values at the locations of streamline prototype vertices and (B) the distances between these vertices and the closest CMB. Across subjects, the sensitivity and precision of the proposed CMB identification method was 96.8 ± 5.0% and 77.7 ± 7.4%, respectively. The calculated correlation coefficient was negative and significant for 12.5 ± 3.5% of WM clusters (p < 0.05, corrected). Our results suggest that, especially in older age, mTBI‐related CMBs can have an adverse effect on surrounding WM tissue, with decreasing distance to the CMB being related to greater WM damage.
Keywords: cerebral micro‐hemorrhages, mTBI, white matter degradation, aging
NEUROLOGY 4‐PLEX A BIOMARKER ANALYSIS WITH BRAIN TISSUE AND BEHAVIORAL CORRELATES IN P301S TAU MICE AFTER REPETITIVE MILD TBI
1USUHS, Bethesda, USA
2Colgate University, Hamilton, USA
3NINR/NIH, Bethesda, USA
Repetitive mild traumatic brain injury (r‐mTBI) is associated with chronic neurodegeneration. Improving diagnosis and treatment of r‐mTBI requires understanding how relatively subtle injury progresses to long term pathophysiology. Translational assessments that inform research in both patients and experimental models are a key to advancing diagnosis and testing treatments. To examine chronic r‐mTBI effects in the context of tau pathology, closed head r‐mTBI (5 daily impacts) was induced in 8‐week old P301S mice expressing human mutant tau. Blood was collected at 6 wks and 4 mths after injury prior to perfusion for brain neuropathology or biochemical fractionation. In non‐injured homozygous mice, these time points correspond to pre‐symptomatic (6 wks) and impaired (4 mths) using a hang time assessment. Serum was analyzed using the Single‐molecule array technology (Simoa™) Neurology 4‐Plex A multiplex assay. In sham and r‐mTBI homozygous mice, neurofilament light chain (NF‐L) was increased by 6 wks and further elevated at 4 mths, while tau and glial fibrillary acidic protein (GFAP) were elevated only at 4 mths. Ubiquitin c‐terminal hydrolase 1 (UCHL1) was not increased by mutant tau or r‐mTBI. Biochemical quantification of soluble tau in the forebrain region under the impact site showed increased total tau and phosphorylated tau based on P301S genotype. Neuropathology demonstrated human tau expression and phosphorylated tau in neurons immunolabeled by HT7 and AT8, respectively, along with neuroinflammation after injury. Finally, behavioral testing differentiated functional effects from both mutant tau and r‐mTBI. Reduced hang time was accelerated by r‐mTBI in hemizygous mice. Social interaction was impaired at 6 wks after r‐mTBI in wild‐type mice yet deficits were already present in sham and r‐mTBI hemizygous mice. These studies show translational feasibility of a promising clinical biomarker assay for analysis of mouse serum, with NF‐L being the most sensitive to tau induced pathology.
Keywords: neurofilament light chain, tau, biomarker, repetitive injury, Traumatic brain injury, axon damage
FACTORS ASSOCIATED WITH MISSED VISITS IN CHRONIC EFFECTS OF NEUROTRAUMA CONSORTIUM (CENC) MULTICENTER LONGITUDINAL MILD TBI STUDY
1Virginia Commonwealth University, Richmond, USA
2HH McGuire VAMC, Richmond, USA
3VA Boston Healthcare System, Boston, USA
4Michael DeBakey VAMC, Houston, USA
5James Haley Veterans Hospital, Tampa, USA
6Minneapolis VA Healthcare System, Minneapolis, USA
7VA Portland Healthcare System, Portland, USA
The CENC Multicenter Observational Study of persons with post‐9/11 combat exposure was established to examine the long‐term effects of mild traumatic brain injury (mTBI) including neurodegeneration. The 1,600+ enrollees are assessed annually, including comprehensive in‐person evaluations at least once every five years and telephone assessments for all other years. This analysis examined potential selection bias of missed longitudinal assessments. Using backwards selection in multivariable model of missed visits, the following covariates were entered to calculate odds ratios: age, gender, race, ethnicity, mTBI group (none, during combat deployment, nondeployment only), depression, posttraumatic stress disorder (PTSD), substance misuse, and student/employment status. In total, 79% of all past due in‐person follow‐up visits were completed and 82% of all past due annual phone appointments were completed, with 76% completing all phone assessments. Younger participants (OR = 1.25, 95% CI: 1.08, 1.45) and participants with PTSD (OR = 1.99, 95% CI: 1.14, 3.49) were more likely to miss their follow‐up in‐person assessments. Latino participants (OR = 1.89, 95% CI: 1.30, 2.72) and participants with combat mTBI (OR = 1.86, 95% CI: 1.12, 3.08) were more likely to miss their annual phone assessments than White participants and those with no mTBI, respectively. Compared to other large longitudinal studies, these visit completion rates are very high. The factors associated with missed visits will inform retention efforts, imputation methods for missing data, and interpretation of future findings. Longitudinal research with military cohorts should consider the challenges of retaining individuals who are younger, Latino, and have PTSD and/or combat‐related mTBI.
Acknowledgment: supported by grant funding; Department of Defense CENC Award W81XWH‐13‐2‐0095, Department of Veterans Affairs CENC Award I01 CX001135.
Keywords: Longitudinal Studies, Military Personnel, Veterans, Traumatic Brain Injury, Mild
DETERMINING THE EFFECT OF TAU AND MITOCHONDRIAL FUNCTION IN RESPONSE TO TRAUMATIC BRAIN INJURY
1Wayne State University, Pharmacology, Detroit, USA
2Wayne State University, Department of Obstetrics and Gynecology, Detroit, USA
3Wayne State University, Institute of Environmental Health Sciences, Detroit, USA
Traumatic brain injury (TBI), defined as damage to the brain resulting from an external mechanical force, can lead to impairment of cognitive and physical function. TBI is an emerging health epidemic with ∼2.5 million incidents severe enough to cause hospitalization or death. This study utilizes Drosophila melanogaster, a highly tractable genetic model organism for studying human diseases, to investigate TBI outcome. Flies subjected to rapid acceleration and impact exhibit TBI related symptoms consistent with other mammalian and human studies. The primary effect of TBI is axonal damage, which when coupled with brain injury triggers a cascade of events increasing phosphorylation of Tau (a microtubule associated protein) and mitochondrial dysfunction. Uninterrupted transport of mitochondria, which harbor the machinery to generate ATP, relies on the ability of phosphorylated Tau to stabilize microtubules. However, aberrant Tau phosphorylation causes depolymerization of microtubules, Tau filament formation, disruption of mitochondrial dynamics and increases cell death. This study hypothesizes that changes in Tau activity and mitochondrial function have an impact in response to TBI. We make use of EGFP fused Tau insertion (Tau‐EGFP) and Tau knock‐out (Tau‐KO) fly lines to assess the impact of TBI on Tau activity. In addition, fly line with selective expression in motor neurons of a fusion of GFP with a mitochondrial import signal (Mito‐GFP) is employed to assess mitochondrial impairment post‐injury. We have observed increased Tau activity, increased mitochondrial activity and locomotion impairments post‐TBI. Our results establish that changes in Tau activity and mitochondrial function play an important role in the outcome of TBI. We further propose to study if TBI mediated mitochondrial dysfunction regulates Tau expression and vice‐versa.
Keywords: TBI, Tau, Mitochondrial, Axonal injury
B13 Neuroprotection
PROTECTIVE ROLE OF AST‐004 IN PIGLET MODEL OF BLUNT TBI
1Emory University and Georgia Tech, Biomedical Engineering, Atlanta, USA
2Children's Hospital of Philadelphia, Critical Care, Philadelphia, USA
3University of Pennsylvania, Bioengineering, Philadelphia, USA
4UT San Antonio, San Antonio, USA
5Astrocyte Pharma, Boston, USA
6Pennsylvania State University, State College, USA
Traumatic brain injuries (TBIs) are a common medical condition with no approved FDA treatment. AST‐004, an adenosine A3 receptor (ADORA3, A3R) agonist has exhibited significant neuroprotective efficacy in mouse and rat models of TBI and stroke. Here, we present evidence that AST‐004 exhibits significant neuroprotective efficacy in a large animal model of TBI. Piglets (4 week‐old females) were subjected to controlled cortical injury (CCI; open skull). A skull‐mounted, spring‐loaded blunt indentation device was deformed approximately 1 cm3 of the right cortical rostral gyrus rapidly (4 ms), with a typical lesion volume (Vinj) of 4% of the cerebrum. Injured piglets were assigned to 5 injury arms (CCI with vehicle or 4 dose levels of AST‐004). AST‐004 was delivered using an intravenous bolus, 1 hour after injury, followed by continuous infusion for 24 hours. Magnetic resonance imaging images acquired 48 hr post‐injury showed that AST‐004 treatment reduced edema formation by 38.5% in the optimal dose group (p < 0.013 AST‐004 [N = 6] vs vehicle [N = 7]). DTI fractional anisotropy also showed a 38.5% improvement (p < 0.05) in white matter injury compared to vehicle. Blood samples were obtained from each pig 1 hr pre‐injury, then post‐injury at 0.33, 1, 3, 24, 48 and 72 hrs. We found plasma GFAP increased significantly at 24 hrs after injury in treated and untreated animals. However, at 24 hours post‐injury, plasma levels of GFAP were significantly lower in pigs treated with AST‐004 (p < 0.007 AST‐004 [N = 6] vs vehicle [N = 7]). Taken together, these data demonstrate the significant potential of AST‐004 in treating TBI in gyrencephalic mammals. Supported by STTR NIH R41NS093756 and Astrocyte Pharmaceuticals.
Keywords: preclinical, TBI, treatment, therapeutic
INTRAPARENCHYMAL APPLICATION OF MATURE B LYMPHOCYTES IMPROVES STRUCTURAL AND FUNCTIONAL OUTCOME AFTER CONTUSION TBI
1Massachusetts General Hospital, Medicine, Charlestown, USA
2Harvard Medical School, Boston, USA
3Massachusetts General Hospital, Pediatrics, Charlestown, USA
Cerebral contusion causes neurological dysfunction mediated in part by inflammatory responses to injury. B lymphocytes are dynamic regulators of the immune system that have not been systematically studied in traumatic brain injury (TBI). We showed previously that topically‐applied mature B cells have immuno‐modulatory properties and strongly promote tissue regeneration, including cutaneous nerve growth, in murine models of acute and chronic skin wounds. Using a mouse controlled cortical impact (CCI) model, we assessed a possible beneficial role of exogenously applied B cells on histopathological and functional outcome after TBI. Mice were injected intraparenchymally at the lesion site with 2 × 106 mature naïve syngeneic splenic B cells, then subjected to CCI. Control CCI mice received equal numbers of T cells or saline, and sham‐injured mice (craniotomy only) were given B cells or saline. Sham‐injured groups performed similarly in motor and learning tests, regardless of treatment. Injured mice treated with B cells showed significantly improved post‐injury Rotarod, Y maze, and Morris water maze (MWM) performance compared to saline‐ or T cell‐treated CCI groups. Moreover, lesion volume in B cell‐treated mice was 40% lower at 35 days post‐TBI while gliosis and microglial activation were significantly reduced as compared to controls. In vivo tracking of exogenous B cells showed that they have a limited lifespan of approximately 14 days in situ and do not appear to proliferate. These data provide proof of principle that local administration of B lymphocytes may represent a therapeutic option for treatment of cerebral contusion, especially when clinical management involves procedures that allow access to the injury site.
Keywords: B cells, lymphocytes, TBI, CCI, learning and memory, inflammation
A NEW KETOGENIC FORMULATION IMPROVES FUNCTIONAL OUTCOME AND REDUCES TISSUE DAMAGE FOLLOWING TRAUMATIC BRAIN INJURY
1Queen Mary University of London, Neurosciences, Surgery and Trauma, London, United Kingdom
2Nutricia Research, Advanced Medical Nutrition, Utrecht, The Netherlands
Traumatic brain injury (TBI) leads to major neurological impairment and at present there is no satisfactory treatment for this condition, which can have life‐changing consequences for individuals. TBI can lead to major tissue disruption, neuroinflammation and axonal damage. Accumulating evidence indicates that a ketogenic diet, which reduces the reliance on carbohydrates for energy supply and provides ketones as an alternative fuel for the brain, has neuroprotective potential in TBI. We hypothesised that a new ketogenic diet formulation, containing docosahexaenoic acid (DHA), medium chain triglycerides (MCT) and free leucine, with a ketogenic weight ratio of 2:1, could have protective effects after TBI. We investigated in a mouse model of TBI whether this new diet could counter the tissue injury and lead to an improved neurological outcome. Adult male C57/BL6 mice received an injury by controlled cortical impact (CCI) and were tested on behavioural tasks for 70 days post‐injury. Following TBI, animals were fed daily with a control diet or the new ketogenic formulation until the end of the study. The new ketogenic diet significantly attenuated the deficit post‐TBI assessed using a modified neurological severity score (mNSS). It also decreased the injury‐induced impairment in the Rotarod test ‐ used to explore motor coordination, balance and strength. Following CCI, mice developed a marked impairment in spatial memory, which was assessed in the Morris Water Maze (MWM). The injury‐induced deficit in the probe trial in the MWM was corrected by the ketogenic diet. The lesion size was reduced by the experimental diet, and the perilesional microglia/macrophage activation was markedly reduced. Furthermore, the injury‐induced loss of oligodendrocytes was fully reversed by the diet. These results suggest that this new ketogenic diet has therapeutic potential in TBI.
Keywords: Traumatic brain injury, Control Cortical Impact (CCI), Functional improvement, Neuroprotection, ketogenic diet (new formulation)
KETOGENIC DIET (KD) TREATMENT IMPLICATIONS ON MTBI IN MICE
1Tel Aviv University, Anatomy, Tel‐Aviv, Israel
2Tel Aviv Sourasky Medical Center, Psychiatry, Tel‐Aviv, Israel
Traumatic brain injury (TBI), is a brain dysfunction without present treatment, caused by a violent blow to the head. In models of various brain injuries, animals fed with ketogenic diet (KD) perform better on learning tasks than those fed standard diet (SD). The main goal was to examine whether KD has a neuroprotective or neuro‐rehabilitative effect on the cognitive deficits in the mTBI mouse model. ICR mice were fed ketogenic or standard diet starting immediately following the trauma. Cognitive and behavioral performance were assessed 7 and 30 days post injury using Elevated Plus Maze (EPM), Y‐Maze and Novel Object Recognition (NOR) tasks. Tail blood was taken for determination of ketone bodies levels at 0, 3, and 7 days post injury and SIRT1 levels in the cortex were assessed using western blot analysis 30 days post injury. The results of the Y‐maze and NOR tasks showed that mTBI mice, maintained on KD, showed better cognitive abilities than those fed SD. EPM analysis shows no difference between all groups, indicating that injury failed to cause any anxiety‐like behavior. Relative to control + SD mice, mice on KD (with or without mTBI) demonstrated a prominent increase in ketone bodies as soon as 3 and 7 days after the KD was initiated. Mice maintained on SD post injury demonstrated SIRT1 reduction when compared to control and KD groups. These results support accumulating evidence that KD may be an effective approach to increase brain resistance to damage and suggest a potential new therapeutic strategy for treating mTBI.
Keywords: Ketogenic Diet, mTBI, learning, mice
COMPENSATORY PROKINETICIN‐2 UPREGULATION DURING TRAUMATIC BRAIN INJURY PROTECTS NEURONAL DEATH VIA FERROPTOSIS INACTIVATION
the First Affiliated Hospital of Nanjing Medical University, 300 Guangzhou Road, Nanjing, Department of Neurosurgery, Nanjing, China
Keywords: Prok2, ferroptosis, traumatic brain injury, ACSL4, lipid oxidation
MRI EVIDENCE OF THERAPEUTIC EFFICACY OF ULTRA‐EARLY (<12 HOURS), EARLY (12‐24 HOURS) AND LATE (>24 HOURS) DECOMPRESSIVE SURGERY IN
University of Maryland School of Medicine, Neurosurgery, Baltimore, USA
In traumatic cervical spinal cord injury (SCI), early decompression might be neuroprotective; however, the relationship between timing of decompression, extent of decompression, and outcome are incompletely understood. We investigated the effect of timing of decompression and long‐term neurological outcome in patients with postoperatively confirmed decompression. Six months after cervical SCI, AIS grade conversion was determined in 72 AIS grades A, B, and C patients whose postoperative MRI confirmed spinal cord decompression. Thirty‐two patients underwent decompressive surgery less than 12 hours from injury, 25 within 12‐24 hours, and 15 more than 24 hours after trauma. Age, gender, injury mechanism, admission AIS grade, intramedullary lesion length (IMLL) on MRI, and surgical technique were not statistically different in‐between groups. One or more grade improvement was 55.6% in AIS grade A, 60.9% in AIS grade B, and 86.4% in AIS grade C patients. Admission AIS motor score (p = 0.0004) and pre‐operative IMLL (p = 00001) were the strongest predictors of neurological outcome. AIS grade improvement was 65.6% in patients undergoing decompressive surgery within 12 hours after trauma, 60% in patients undergoing surgery within 12‐24 hours, and 80% when decompression was performed more than 24 hours after injury (p = 0.424). Multiple regression analysis of all significant and marginally significant variables revealed that the only significant variable predictive of AIS grade conversion to a better grade was IMLL (odds ratio 133.51, CI 11.68‐1525.71, p < 0.0001). In patients with postoperative MRI confirmation of decompression following traumatic cervical SCI, pre‐operative IMLL and not the timing of surgery appears to determine long‐term neurological outcome.
Keywords: Trauma, Spinal Cord Injury, Timing of Surgery, Decompression, Outcome
THE VOLTAGE‐GATED PROTON CHANNEL HV1 IMPAIRS RECOVERY AFTER MOUSE SPINAL CORD INJURY THROUGH NOX2/ROS SIGNALING
1University of Maryland, Department of Anesthesiology & Center for Shock, Trauma and Anesthesiology Research (STAR), Baltimore, USA
2Mayo Clinic, Department of Neurology, Rochester, USA
The voltage‐gated Hv1 channel is a recently cloned ion channel that rapidly removes protons from depolarized cytoplasm and is highly expressed in the immune system. Hv1 is required for NADPH (NOX)‐dependent ROS (reactive oxygen species) production during phagocyte respiratory burst. Excessive NOX2/ROS production is critical in the pathophysiology of SCI as it non‐selectively damages neurons and glia. Microglial Hv1 regulates intracellular pH and aids in NOX2‐dependent generation of ROS. Thus, Hv1 is a unique target for controlling multiple NOX activities and ROS production. In mouse models of brain ischemia, studies point to an acute neuroprotection phenotype in Hv1 knockout (KO) mice. However, neither the precise cellular mechanisms nor the role of Hv1 in the pathophysiology of SCI is fully understood. Adult female Hv1 KO and WT mice were subjected to moderate contusion SCI using the Infinite Horizon spinal cord impactor. Injured spinal cord tissue was harvested at 1, 3, 7, 14, and 28 days post‐injury, and processed for Hv1 mRNA and protein expression by qPCR and Western blot (WB). qPCR analysis showed a rapid up‐regulation (40 folds) of Hv1 mRNA, starting at 3d post‐injury and continuing up to 28d. This was confirmed in CD11b+ microglia/macrophages isolated from adult spinal cord at 3d post‐injury. WB and IHC showed that Hv1 significantly increased after SCI and is localized predominantly in microglia/macrophages. IHC and flow cytometry analysis showed that Hv1‐KO mice exhibited significantly attenuated NOX2/ROS production, IL‐1β signaling, and neuronal cell death at 3d and 7d post‐injury. BMS assessment of locomotor function showed marked improvement in Hv1 KO mice, which correlated with increased spare white matter. Together, the present data suggest an important role for Hv1 in regulating NOX2/ROS‐mediated secondary injury after SCI. Thus, Hv1 represents a potential therapeutic target that may lead to novel clinical therapeutic strategies.
Keywords: Voltage‐gated proton channel Hv1, Spinal Cord Injury, NOX2, ROS, Microglia/Macrophage, Functional Outcome
SPINAL CORD AND MULTI‐ORGAN REGIONAL BLOOD FLOW AUTOREGULATION SECONDARY TO BLOOD PRESSURE CHANGES IN ANESTHETIZED YUCATAN MINIPIG
1University of Miami, Miller School of Medicine, Miami Project To Cure Paralysis, Miami, USA
2University of Miami, Miller School of Medicine, Pediatrics Critical Care, Miami, USA
3University of Miami, Miller School of Medicine, Neurological Surgery, Miami, USA
Microvascular effects of mean arterial pressure (MAP) variations after spinal cord injury (SCI) are not well established. Current guidelines to elevate MAP after SCI aim to improve neurological recovery by increasing blood flow (BF) at epicenter regions prone to ischemia; but may also accentuate hemorrhage and edema from injured vessels, amplifying secondary injury. Furthermore, surgery and general anesthesia impose artificial conditions in SCI translational research. To quantify spinal cord (SC) regional blood flow (RBF) changes, we used multiple timed fluorescent microsphere (FM) infusions under different anesthetic paradigms and MAP variants.
Acknowledgments: Supported by the Craig Neilsen Foundation.
Keywords: SCI, Autoregulation, Blood Flow
REPETITIVE CLOSED HEAD INJURY RESULTS IN ALTERED DENDRITIC ARBORS IN THE HIPPOCAMPUS
1VA New Jersey Health Care System, Pharmacology, Physiology & Neuroscience, Rutgers‐ NJMS, East Orange, USA
2Bay Pines VA Healthcare System, R&D, Bay Pines, USA
3Sackler School of Medicine, Anatomy & Anthropoloigy, Tel Aviv, Israel
4VA New Jersey Health Care System, R&D, East Orange, USA
At least 15% of deployed service personnel have received mild traumatic brain injuries and these also occur in 0.5% of the general worldwide population each year. Mild injuries can result in cognitive and other deficits and there is currently no effective treatment. Multiple mild TBI incidents can increase the risk for other neurodegenerative disorders. Dysregulation of gene expression is an important factor in the outcome of traumatic brain injury with or without treatment. Our lab and others have shown that activation of transcription factors Nuclear Factor Erythroid 2‐like 2 (Nrf2) and Peroxisome‐proliferator‐activated receptor (PPARγ) provides robust neuroprotection in both cell and animal models of TBI. We examined the effects of repetitive injury and treatment on the state of dendritic arbors and spines in the hippocampus. We used a weight drop closed head injury model with a total of 5 injuries with 1 week intervals in between. The dentate gyrus region of the hippocampus was examined in 5 mice per group. After Golgi staining, granule cells were analyzed and we found that spine density was reduced in injured brains by about 25% (P < 0.05) but only 14% reduced when treatment was administered to the injured mice. Also, total dendritic length per cell was also reduced by the repetitive injury. The changes in the complexity of the dendritic arbor and spine configurations could explain some of the memory deficits that we have observed. Consideration of alterations in gene expression, structural results, and behavioral performance provide clues to potential neuroprotective approaches. Supported by the VA, DOD, and Veterans Bio‐Medical Research Institute.
Keywords: Nrf2, PPARg, Repetitive Injury, Golgi Staining
TACROLIMUS‐BASED IMMUNE SUPPRESSION FOLLOWING TRAUMATIC BRAIN INJURY NEGATIVELY AFFECTS COGNITION
Walter Reed Army Institute of Research, Brain Trauma Neuroprotection Branch, Center for Military Psychiatry and Neuroscience, Silver Spring, USA
Tacrolimus is a calcineurin inhibitor with immunosuppressive properties that is frequently employed in post‐transplant immunosuppressant cocktails with mycophenolate and steroids. Tacrolimus has demonstrated neuroprotective effects in models of ischemia, spinal cord injury (SCI), and traumatic brain injury (TBI). Thus, utilization of tacrolimus in cell‐based therapy for central nervous system (CNS) injury or disease may confound results. This study aimed to identify any potential neuroprotective effects of tacrolimus‐based immunosuppression in a preclinical model of penetrating ballistic‐like TBI (pTBI). Adult rats were randomized into TBI or Sham groups with or without immune suppression. PTBI was performed unilaterally in the right hemisphere of anesthetized rats. Five days post‐pTBI, daily intraperitoneal (IP) administration of 1mg/kg tacrolimus (Prograf) was initiated. 30mg/kg mycophenolate mofetil (CellCept) was administered IP daily 7‐16 days post‐PBBI. 10mg/kg methylprednisolone acetate (Depo‐Medrol) was delivered 7 days post‐injury IP and then weekly at 1mg/kg. Control treatment groups received saline (vehicle). Rotarod (7 days and 6 weeks) and Morris water maze (MWM; 5 weeks) assessments were conducted post‐treatment. Peripheral blood was sampled on 2, 7, 30, and 90 days post‐treatment at 1hour post‐drug administration for complete blood count (CBC) analysis. Histopathological analysis for lesion volume and astrocyte activation were conducted at 1, 6, and 12 weeks post‐treatment. By treatment day 7, the Tacrolimus‐based cocktail significantly decreased the white blood cell (WBC) count, primarily affecting the lymphocyte population, indicating that 7 days of Tacrolimus‐based immune‐suppression is optimal for neural stem cell transplantation studies. No neuroprotective effects from Tacrolimus were detected on lesion volume and cortical volume loss assessments. Nor were any beneficial effects observed on motor or cognitive outcomes. In fact, pTBI and sham animals treated with Tacrolimus actually performed worse in the MWM task versus vehicle‐treated controls which suggests the long‐lasting lymphocyte population reduction may be associated with the worsened cognitive outcome.
Keywords: TBI, tacrolimus, cognition, pre‐clinical
ALTERNATIVE BRAIN ENERGY BIOFUELS ALC AND GTA IMPROVE MITOCHONDRIAL BIOENERGETICS FOLLOWING PENETRATING TRAUMATIC BRAIN INJURY
Walter Reed Army Institute of Research, BTNN, Silver Spring, USA
Mitochondria play a pivotal role in maintaining brain energy homeostasis following traumatic brain injury (TBI). While glucose serves as the primary metabolic substrate for the brain energy production (i.e. adenosine triphosphate, ATP), other alternative biofuels are being evaluated to mitigate metabolic disruption following acute TBI. Time‐course analysis of mitochondrial bioenergetics in a preclinical model of penetrating ballistic‐like brain injury (PBBI) showed altered substrates utilization and impaired bioenergetics profile evident from 30min post‐injury out to 14d. The current study tested acetyl L‐carnitine (ALC) and glyceryl triacetate (GTA) as alternative energy supplements for TBI. These drugs were selected for testing based on their ability to supplement “acetate” substrates for mitochondrial ATP synthesis and bypass key metabolic reactions of glucose oxidation. Dose response (D‐R) experiments for each drug were conducted to evaluate therapeutic efficacy based on improvement in bioenergetics measured at 7d post‐PBBI. ALC (50‐500 mg/kg or vehicle) was administered intraperitoneally (i.p.) at 15min and 6h post‐injury, then once daily for 7d. GTA (1‐7.5g/kg or vehicle) was administered intragastrically at 15min and 6h post‐injury, then once daily for 7d. The ALC 50mg/kg group had significantly higher mitochondrial ATP synthesis rates (*p < 0.05 vs. vehicle) at 7d post‐PBBI. Likewise, GTA displayed dose‐dependent improvements in bioenergetics, particularly GTA (7.5mg/kg) group had significantly higher ATP synthesis rates (*p < 0.05 vs. vehicle) at 7d post‐PBBI. Furthermore, ongoing therapeutic window experiments indicate that ALC is effective even when initial treatment is delayed to 6h post‐injury. Overall, these observations suggest that “acetate” therapy may serve as an alternative energy biofuels following acute brain trauma. Support: US_Army_CCCRP_H_001_2018_WRAIR. Disclaimer: The opinions or assertions contained herein are the private ones of the author/speaker and are not to be construed as official or reflecting the views of the Department of Defense, the Uniformed Services University of the Health Sciences or any other agency of the U.S. Government.
Keywords: Mitochondria, Acetate Therapy, Dose‐Response, Therapeutic Window, Penetrating Traumatic Brain Injury (pTBI)
NICOTINE AMELIORATES MOTOR AND COGNITIVE DEFICITS IN RATS FOLLOWING PENETRATING BRAIN INJURY
Walter Reed Army Institute of Research, Brain Trauma Neuroprotection Branch, Center for Military Psychiatry and Neuroscience, Silver Spring, MD, USA
Neuropathological and behavioral/cognitive impairments resulting from traumatic brain injury (TBI) remain a concern for the worldwide population. However, efficacious treatments are lacking. Nicotine therapy represents one promising avenue of research as nicotine enhances attention, memory, and fine motor abilities in smokers and non‐smokers. Additionally, nicotine has been shown to result in cognitive enhancement and the mitigation of molecular pathology following CCI in rats. This study aimed to evaluate the efficacy of subcutaneously administered nicotine for reducing neuropathological and behavioral/cognitive ailments in a rodent model of penetrating ballistic‐like brain injury (PBBI). Rats were divided into seven groups: PBBI‐Nicotine 0.375 mg/kg/day, PBBI‐Nicotine 0.75 mg/kg/day, PBBI‐Nicotine 1.5 mg/kg/day, PBBI‐Nicotine 3.0 mg/kg/day, PBBI‐Nicotine 6.0 mg/kg/day, PBBI‐Vehicle, and Sham. Immediately following PBBI, administration of nicotine or vehicle began via a subcutaneously implanted osmotic pump, which continued throughout the study period. Motor function was evaluated at 7 and 10 days post‐injury. Cognition was assessed by spatial memory performance at 13‐17 days post‐injury and working memory performance at 22 days post‐injury. Animals were perfused on day 23 post‐PBBI. Nicotine administration at 6mg/kg/day significantly improved post‐PBBI motor function, though no improvements in cognitive parameters were observed. Interestingly, 3mg/kg/day improved memory recall deficit, reduced attention impairment, and promoted working memory performance, though no therapeutic effect on spatial learning or motor function was observed. Doses ranging from 0.375 to 1.5 mg/kg/day did not ameliorate any assessed parameter. Nicotine did not demonstrate a neuroprotective effect as determined by lesion volume and cortical volume loss analyses. In summary, chronic administration of higher doses of nicotine showed therapeutic benefit on motor and cognitive outcomes, with an optimal dosage range between 3 and 6 mg/kg/day. Importantly, nicotine plasma levels reached by these doses in the rat can be achieved in humans via transdermal patch, equating to 1‐2 packs of cigarettes per day.
Keywords: Nicotine, Severe TBI, Point‐of‐Injury, PBBI
B14 Neurotransmitter
CHRONIC CONTUSION INJURY DECREASED GLUTAMATERGIC AXONAL INPUTS TO SPINAL EJACULATION GENERATOR IN MALE RATS: TIME COURSE
Kiran K. Soni,
Kent State University, Biological Sciences, Kent, USA
Chronic spinal cord injury (SCI) results in sexual dysfunction in men, including anejaculation. Ejaculation is regulated by a spinal reflex generator in the lumbosacral spinal cord. This generator consists of neurons located in spinal levels L3‐4 that were named for their projections to the thalamus (lumbar spinothalamic cells: LSt cells). LSt cells convert the sensory inputs during sexual activity into a coordinated autonomic and motor output required for ejaculation. Processing of sensory inputs requires glutamate‐induced activation of NMDA receptors in LSt cells. We previously demonstrated that contusion spinal injury at T6 severely disrupted ejaculatory reflexes triggered by stimulation of the dorsal penile nerve, 4‐6 weeks after injury. Therefore, we hypothesize that SCI impaired the processing of sensory signals required to trigger ejaculation. Indeed, we recently showed that contusion injury significantly reduced glutamatergic inputs to LSt cells, evidenced by a significant reduction of axon terminals expressing vesicular glutamate transporter 1 or 2 (VGlut1 or VGlut2) in contact with LSt cells. In the current study, we tested the time course by which this reduction in glutamatergic inputs to LSt cells after SCI occurs. Male Sprague Dawley rats received a contusion injury at spinal levels T6 and were perfused 1 day, 1, 2, or 4 weeks later. Controls consisted of animals with sham surgery or no surgery and were perfused at the same time intervals. Spinal cords were immunoprocessed for galanin (LSt cell marker) and VGlut2. Quantitative confocal analysis of putative synaptic inputs to LSt cells showed that SCI significantly reduced VGlut2‐inputs to LSt cells, at all time points, with increasing further loss of VGlut2‐inputs with each greater time point. In contract, SCI did not affect numbers or soma sizes of galanin‐immunoreactive cells. Together, these data demonstrate an immediate and long‐lasting impact of SCI on excitatory glutamatergic inputs to LSt cells and suggest both early as well as chronic timepoints as targets for intervention and treatment.
This research is funded by DOD SCI 150225 to LMC
Keywords: Sexual function, Ejaculation, Glutamate, Spinal interneurons
EFFECTS OF SPINAL CORD INJURY ON LOCALIZATION AND FUNCTION OF MU OPIOID RECEPTORS IN SPINAL EJACULATION GENERATOR IN MALE RATS
Siddharth S. Gaikwad2, Natalie Kozyrev3,
1Kent State University, Biological Sciences, Kent, USA
2University of Mississippi Medical Center, Graduate Program in Neuroscience, Jackson, USA
3Western University, Robarts Research Institute, London, CA
Spinal cord injury (SCI) has devastating effects, including ejaculatory dysfunction. Surveys among SCI men places recovery of sexual function as a high priority, but available treatment options are invasive. Ejaculation is regulated by the spinal ejaculation generator (SEG), which consists of lumbar spinothalamic cells (LSt). LSt cells convert sensory signals during mating into coordinated autonomic and motor responses required for ejaculation via axonal release of neuropeptides onto preganglionic and motor neurons. These neuropeptides include enkephalin, acting on mu opioid receptors (MOR). However, it is currently unknown where within the SEG MOR are expressed. In addition, we have previously shown that chronic spinal contusion injury in rats severely disrupts ejaculatory function similar to the deficits in humans. Here, we examined effects of SCI on MOR expression in the SEG and effects of MOR agonist on ejaculatory reflexes. Spinal cord sections of SCI and sham surgery animals (n = 4 each; 5 weeks after T6 contusion injury) were immunostained for MOR and choline acetyltransferase (ChAT) to reveal MOR expression in neurons in the intermediolateral cell column, central autonomic nucleus, sacral parasympathetic nucleus and sacral nucleus of the bulbocavernosus, as well as in LSt cells. SCI did not have an apparent effect on overall localization of MOR in neurons in the SEG. Finally, sham and SCI male rats (n = 11 each; 5 weeks after T5‐6 contusion injury) received intrathecal infusions of MOR agonist (D‐Ala2, N‐Me‐Phe4, glycinol5) – Enkephalin; DAMGO; 1 nmol/1μL) 2 hours after an acute spinal transection and ejaculatory reflexes were recorded. DAMGO infusions triggered ejaculatory reflexes in both sham and SCI groups. Together, these data show that MOR is expressed throughout the rat SEG and may form a potential target for treatment options for ejaculatory dysfunction after SCI. Supported by Craig H. Neilsen Foundation # 546401 to LMC.
Keywords: mu opioid receptor, ejaculation, sexual function, thoracic injury
TRAUMATIC BRAIN INJURY‐INDUCED LATE‐ONSET SENSORY HYPERSENSITIVITY AND CIRCUIT FUNCTION: DOES SEX MATTER?
1University of Arizona Phoenix, Child Health, Phoenix, USA
2BARROW Neurological Institute at Phoenix Children's Hospital, Phoenix, USA
3University of Bath, Bath, UK
4Phoenix VA Healthcare System, Phoenix, USA
The incidence of traumatic brain injury (TBI) in women rose from 25% to 40% between 2004 and 2014, with women reporting a higher prevalence for persistent TBI symptoms. Yet, there is a paucity of translational studies that evaluated females at chronic time points. Traditionally, TBI reports are overwhelmingly focused on males. Fluctuating levels of ovarian hormones in naturally cycling females inferred by estrous cycle are predicted to be neuroprotective and add variability to outcome measures. Previously, we reported late‐onset persisting sensory hypersensitivity that paralleled changes in circuit function after midline fluid percussion injury (mFPI) in male rat. Presently, we test the hypothesis the female estrous cycle will influence the severity of sensory hypersensitivity and relevant circuit functions in comparison to males. Adult female Sprague Dawley rats were habituated to handling, then estrous cycles were tracked daily for 28 days following mFPI or sham surgery. Age‐matched male sham and injured rats were similarly handled (n = 5‐8/group). At 28dpi, the whisker nuisance behavioral task was performed followed by in vivo amperometric recordings of glutamate in the ventral posterior medial nucleus of the thalamus (VPM) and the primary somatosensory cortex (S1BF). We found that female rats developed similar late‐onset whisker sensory sensitivity with injury associated with alterations in transient glutamate events in the VPM or S1BF, similar to males. Further, in female rats, TBI during follicular (high estrous) phase showed fluctuations in the cycling, suggesting a link between brain injury and ovarian hormones. These findings do not reveal sex‐specific factors influencing late‐onset whisker sensory sensitivity and underlying circuit function. However, changes in estrous cycle would influence circulating ovarian hormone levels, potentially influencing circuitry with higher expression of hormone receptors. Support: NIH(R01NS100793)‐PCH Mission Support
Keywords: Traumatic brain injury, Amperometry, Estrous cycle, Thalamocortical system
HIPPOCAMPAL SNARE PROTEIN REDUCTIONS IN HETEROZYGOUS CYSTEINE‐STRING PROTEIN ALPHA KNOCK‐OUT MICE AFTER CONTROLLED CORTICAL IMPACT
University of Pittsburgh, Neurosurgery, Pittsburgh, USA
Impairments in cognitive function up to one year after traumatic brain injury (TBI) are reported in patients and recapitulated in experimental models of TBI. Previous studies implicate neurotransmission impairment as a contributor to cognitive dysfunction after TBI, but additional work is warranted to better understand mechanisms underlying this impairment. Neurotransmitter release is facilitated by formation of the soluble N‐ethylmaleimide‐sensitive factor attachment protein receptor (SNARE) complex. Cysteine‐string protein alpha (CSPα) is a chaperone important for SNARE complex formation. We previously showed reduced SNARE complex formation and CSPα abundance after TBI. To test the importance of CSPα on neurobehavioral function and SNARE complex formation after TBI, CSPα heterozygous (CSPα HET) knock‐out mice were utilized. We hypothesized CSPα HET mice exhibit reduced SNARE complex formation and exacerbated neurobehavioral dysfunction post‐injury. CSPα HET and wild‐type (WT) mice were subjected to controlled cortical impact (CCI; 1.8mm, 6 m/s, 150msec dwell) or sham surgery. Two cohorts were generated to test the effects of genetically reduced CSPα at 2 weeks (n = 9‐10/group) and 3 months (n = 10/group) following CCI. In the 2wk cohort, motor performance on 1‐5d post‐injury revealed no differences between groups. Assessment of spatial acquisition in the Morris water maze task on 9‐13d post‐injury showed a significant injury effect (p < 0.05), independent of genotype. Evaluation of spatial memory performance at 14d post‐injury revealed no difference between groups. Immunoblotting revealed reduced hippocampal CSPα abundance (p < 0.01) and reduced SNARE complex formation (p < 0.05) in sham and CCI‐injured CSPα HET mice compared to sham and CCI‐injured WT mice at 2wk post‐injury. In the 3mo cohort, a significant injury effect (p < 0.05) was observed in spatial memory performance, independent of genotype. While genetic reduction of CSPα did not alter neurobehavioral function at 2wk or 3mo post‐injury, immunoblot data revealed reduced SNARE complex formation. Future work will examine the efficacy of therapeutic interventions, dependent upon CSPα, to promoting SNARE complex formation.
Acknowledgement: NIH‐NS40125, NIH‐NS060672, VAI01RX001127, 1‐F32NS090748, The Pittsburgh Foundation
Keywords: Synapse, SNARE
B15 Pediatric
HOW DO CHILDREN COMPARE TO ADULTS AS TBI RESEARCH SUBJECTS?
Massachusetts General Hospital, Neurosurgery, BOSTON, USA
Few longitudinal studies include patients of all ages from infancy through late life. We sought to determine whether inclusion of pediatric patients helped or impeded attainment of study goals. TRACK‐TBI is a multicenter study collecting clinical, imaging, biospecimen, and outcome data from subjects of all ages and injury severity throughout one year. We compared pediatric to adult subjects for participation and completion of study milestones. 272 subjects enrolled, receiving stipends after each milestone. Followup rates and milestone completion were tracked. Coordinator effort was estimated by number of telephone contacts needed to schedule a successfully completed followup. Comparisons of medians, interquartile ranges and percentages were made using chi‐square test of homogeneity for categorical and Mann‐Whitney U tests for continuous variables. After exclusions, 100 pediatric (median age 8 years, 62% male) and 102 adult (median age 43 years, 56% male) subjects were analyzed. 48% of pediatric subjects and 24% of adults were admitted to the Intensive Care Unit (ICU), 42% pediatric and 25% adults were admitted to a non‐ICU unit, and 10% of pediatric and 52% adult subjects were discharged from the Emergency Department. At 2 week, 3 month, and 6 month followup timepoints, neurocognitive assessment completion rates were comparable between the two subject groups (pediatric 86%, 79%, 71%; adults 87%, 72%, 69% respectively). Pediatric subjects had a significantly higher 12‐month neurocognitive assessment completion rate (70%) than adults (55%) (p = 0.03). Pediatric subjects were more likely to complete all 4 followups (55% vs. 43%). Effort to schedule a completed followup visit was lower for children for the overall study (p = 0.03) and per each followup timepoint (p = 0.01). Few single studies enroll patients across the entire age spectrum. The current findings demonstrate that pediatric patients had higher followup rates and required less effort from researchers to successfully complete milestones. Besides the obvious gain in scientific knowledge about children, results suggested no detriment to including pediatric patients in combined longitudinal research studies; in fact, their inclusion may be beneficial for study goals.
Keywords: Traumatic Brain Injury, Pediatric/Adult Subjects, Followup Assessment, Longitudinal Study
A PERFECT STORM: DEVELOPMENT OF UNILATERAL HEMISPHERIC HYPODENSITY IS AGE‐DEPENDENT IN A LARGE ANIMAL MODEL OF SEVERE TBI
1Harvard Medical School/ MGH, Neurosurgery, Boston, USA
2Harvard Medical School/MGH, Neurology, Boston, USA
Hemispheric hypodensity (HH) is a severe injury pattern in which the hemisphere underlying a subdural hematoma (SDH) exhibits damage that evolves over hours to days, spans multiple vascular territories, and often results from abusive head trauma. Using our model of unilateral HH, we tested the effect of age on the amount and distribution of tissue damage in piglets of similar maturity to human infants (1‐week‐old, “infants”) vs. toddlers (1‐month‐old, “toddlers”). Focal injuries were scaled to brain size (cortical impact, SDH, mass effect) and focal seizures, global apnea, and hypoventilation were induced modeling the pathoanatomic lesions and clinical manifestations of HH in children. At 24 hours post‐injury, “toddlers” had wide‐spread hypoxic‐ischemic‐type damage encompassing most of the ipsilateral cortex with sparing of deep brain regions and the contralateral hemisphere while “infants” had less damage that was bilateral. Both ages required intensive care, but “infants” had more profound neurologic dysfunction and persistent metabolic acidosis compared to “toddlers”. The proportion of piglets that had unilateral HH was greater in “toddlers” vs. “infants” (67 vs. 11%; P = 0.049). Despite unilateral injection, SDH was unilateral in “toddlers” but not “infants” and was not correlated to damage in either age. SDH indirectly produced a focal subarachnoid hemorrhage (SAH; P = 0.03), which was positively correlated to damage in both ages (P < 0.005). Seizure duration was equivalent between ages and was positively correlated with ipsilateral hemispheric damage in “toddlers” (P = .012) but not “infants” (P = 0.2). In conclusion, “toddlers” had a greater pathophysiologic response to SAH and seizures, which may induce spreading of damage throughout the ipsilateral hemisphere. We are currently evaluating age‐dependent mediators of damage, which may serve as therapeutic targets that reduce the evolution of HH.
Keywords: gyrencephalic, abusive head trauma, subdural hematoma, subarachnoid hemorrhage, traumatic seizures, hemispheric hypodensity
TRKB AGONISM CONFERS NEUROPROTECTION IN A MOUSE MODEL OF PEDIATRIC TRAUMATIC BRAIN INJURY
1Monash University, Department of Neuroscience, Melbourne, Australia
2University of Melbourne, Department of Neuroscience and Anatomy, Parkville, Australia
Young children have a high risk of sustaining a traumatic brain injury (TBI), which can have debilitating life‐long consequences. Importantly, the young brain shows particular vulnerability to injury, which is likely attributed to ongoing development and maturation at the time of insult, including myelination. Here, we examined the role of tropomyosin receptor kinase B (TrkB) in pathological and neurobehavioral outcomes after pediatric TBI, hypothesizing that promoting TrkB signalling would minimise tissue damage and support functional recovery. We focused on white matter tracts, the corpus callosum and external capsules, based on recent evidence that TrkB is critical for oligodendrocyte myelination. Male mice at postnatal day 21 received moderately‐severe experimental TBI or sham surgery, and administered saline vehicle or the small‐molecule partial TrkB agonist LM22A4 (5mg/kg/day for 14 days, intranasally). Behavior testing was performed at 4 weeks post‐injury, and brains collected at 5 weeks for sectioning and staining. TBI mice showed hyperactivity and reduced anxiety, but normal sensorimotor function and sociability at 5 weeks post‐injury. LM22A4 ameliorated the abnormal anxiolytic phenotype in TBI mice. Considerable loss of grey and white matter tissue in TBI‐vehicle treated mice was detected by volumetric analyses of cresyl violet‐stained brain sections. However, this tissue loss was significantly reduced in TBI‐LM22A4 treated mice. Immunostaining for myelin basic protein, and the novel label‐free imaging modality, spectral confocal reflectance microscopy (SCoRe), revealed persistent myelin debris in TBI brains, which was greater in TBI‐vehicle versus TBI‐LM22A4 mice. Surprisingly, quantification of immature (Olig2+/PDGFRalpha+) and mature oligodendrocytes (Olig2+/CC1+) did not reveal any effects of TBI or drug treatment in the corpus callosum or external capsule. Together, these findings demonstrate a neuroprotective effect of targeting TrkB signalling after injury to the developing brain. However, further work is needed to understand the underlying mechanisms.
Keywords: TrkB, neuroprotection, behavior testing, spectral confocal reflectance microscopy
MICE BORN TO MOTHERS WITH GESTATIONAL BRAIN INJURY HAVE DISTORTED BRAIN CIRCUITRY AND DIFFERENTIAL IMMUNE RESPONSES
1BARROW Neurological Institute at PCH, Phoenix, USA
2UA COM‐ Phoenix, Child health, Phoenix, USA
3UA COM‐ Phoenix, BMS, Phoenix, USA
4Phoenix VA Health Care System, Phoenix, USA
Intimate partner violence (IPV) affects 1:4 women with up to 90% experiencing traumatic brain injury (TBI). Moreover, IPV and pregnancy often co‐occur. Fetal development is sensitive to stress, peripheral inflammation, and infection, which may be augmented by gestational TBI in mothers. We hypothesized gestational TBI in mothers would lead to increased anxiety‐like behavior, susceptibility to infection, dysbiosis in gut microbiome, and distorted brain circuitry in offspring. Pregnant dams received either diffuse TBI or sham injury 12 days post‐coitum. After giving birth, a subset of mixed‐sex pups from TBI and sham mothers were assessed for cortical circuitry using laser scanning photostimulation (LSPS) at PND25‐32. All other pups were assessed for cognitive, anxiety‐like, and depressive‐like behaviors and gut microbiome from PND30‐80. After PND80, pups received LPS (1 mg/kg, i.p.) and blood was drawn 6hrs post‐LPS. After 24hrs, pups were euthanized and blood and tissue were harvested. TBI and sham offsprings were comparable sizes. Using LSPS functional circuit mapping, we found significantly altered intra‐laminar connectivity onto prefrontal layer 5 pyramidal neurons in male TBI offspring compared to males sham offspring (F(15, 208) = 10.82, p < 0.0001). After LPS injections, pups from TBI mothers had significantly smaller neutrophil populations in blood 6hrs post‐LPS than pups from sham mothers (t(23) = 3.253, p = 0.0035), without significant differences 24hrs post‐LPS. No overt behavioral differences were observed between litters, behavior and microbiome analyses are ongoing. These results show the first developmental consequences of TBI during pregnancy on offspring's cortical circuitry and inflammatory system. These findings necessitates intervention through public health and rapid TBI therapy to mitigate two lives affected by post‐injury symptoms. Funding: PCH Mission Support and BNI@PCH
Keywords: Gestation traumatic brain injury in mothers, Fetal development, Laser scanning photostimulation, Midline fluid percussion injury
SELF‐GUIDED REHABILITATION IMPROVED COGNITIVE PERFORMANCE AFTER DIFFUSE TRAUMATIC BRAIN INJURY IN JUVENILE RATS
1University of Arizona College of Medicine‐Phoenix, Department of Child Health, Phoenix, USA
2BARROW Neurological Institute at Phoenix Children's Hospital, Phoenix, USA
3Arizona State University, Tempe, USA
4Phoenix VA Health Care System, Phoenix, USA
A traumatic brain injury (TBI) experienced early in life affects developmental and functional outcomes, especially when left untreated. Clinical and experimental TBI disrupt cognitive performance, for which a critical need arises to develop experimental rehabilitation strategies that mitigate cognitive and motor deficits. We hypothesized that rehabilitation targeting spatial and contextual memory circuits would prevent the onset of injury‐induced cognitive impairments in juvenile rats. Rehabilitation occurred in a box with a peg board floor that allowed pegs to be inserted in designated layouts (Peg Forest Rehabilitation; PFR). Male and female juvenile rats (post‐natal day 35; n = 24) were subjected to midline fluid percussion or sham injury. One‐week post‐injury, rats were exposed to PFR or cage control exploration (15 min/day). PFR allowed free navigation through random configurations of the peg‐filled arena for 10 days over 2 weeks. Control rats remained in home cages in the center of the arena with the peg‐board removed for 15min/day/10days. One‐week post‐rehabilitation (1 month post‐injury), cognitive performance was assessed for short‐term (novel object recognition; NOR), long‐term (novel location recognition; NLR), and working (temporal order recognition; TOR) memory performance calculated as a discrimination index between novel and familiar objects. An overall effect on NOR discrimination index existed in females (F(3,8) = 4.050, p = 0.050), with TBI‐PFR rats having the highest discrimination index. Overall effects existed on percent time spent between objects in NOR (males: F(3,8) = 59.67, p < 0.001; females: F(3,8) = 14.67, p = 0.0013), NLR (females: F(3,8) = 5.667, p = 0.0222), and TOR (males: F(3,8) = 12.67, p = 0.0021) tasks. Thus, the passive, intermittent PFR that involves dynamic, novel spatial navigation can prevent TBI‐induced cognitive impairment in juvenile rats. PFR serves as a therapeutic intervention to investigate cellular and molecular mechanisms of effective rehabilitation. Spatial navigation training may have clinical efficacy.
Keywords: Pediatric TBI, Learning and memory, Rehabilitation, mTBI
ASSOCIATED RISK FACTORS TO PREDICT PEDIATRIC NON‐ACCIDENTAL HEAD TRAUMA
1University of Arizona College of Medicine‐Phoenix, Department of Child Health, Phoenix, USA
2BARROW Neurological Institute at Phoenix Children's Hospital, Phoenix, USA
3Phoenix Children's Hospital, Phoenix, USA
4Phoenix VA Healthcare System, Phoenix, USA
Head trauma is associated with approximately 70% of infant deaths and promotes infant disability. Injury patterns differ between inflicted and unintentional head trauma, and these patterns can enhance screening and detection. The purpose of this research was to analyze patient and injury characteristics associated with inflicted head trauma to develop a pre‐admission screening algorithm. We performed a single‐institution, retrospective review of all patients suspected of non‐accidental head trauma (NAHT) from 2010‐2017 from a hospital forensic database. Data were collected on demographics, hospitalization, injury, and family characteristics on fatal and non‐fatal head trauma. Differences between patients with inflicted and unintentional head trauma were determined by chi‐square tests. Risk factors for inflicted head trauma were identified by unadjusted odds ratios from logistic regression. Adjusted odds ratios (AOR) were used to assess area under the receiver operating characteristic (AUROC) curve and calculate sensitivity and specificity. Of 804 patients with head trauma (91% <3yo), 276 had a determination of probable NAHT, 343 of probable not NAHT, and 185 were undetermined. Key risks associated with inflicted head trauma were bruising away from the injury (AOR = 6.1[p < .001]), multiple fractures (AOR = 9.5[p < 0.001]), unknown/unreported method of injury (AOR = 3.9[p < .001]), care‐giver history of substance abuse (AOR = 8.8[p < 0.001]), prior Department of Child Safety reports (AOR = 2.1[p < 0.032]), prior police involvement (AOR = 5.3[p < 0.001]), domestic violence (AOR = 2.7[p < 0.014]), and unknown number of adults at home (AOR = 9.5[p < 0.001]). Eight risk factors accounted for 83% of the AUROC analysis with 73% sensitivity, 90% specificity for inflicted head trauma. A risk factor profile for NAHT can identify probable NAHT in the emergency department, urgent care, or primary care. Risk factors justify social change to reduce the incidence of NAHT.
Keywords: Abusive Head Trauma, Non‐Accidental Head Trauma, Pediatric brain injury, inflicted head trauma
DIFFERENCES IN BIOMARKER LEVELS IN MALES VS FEMALES IN CORRELATION WITH GOS‐E PEDS AFTER PEDIATRIC TRAUMATIC BRAIN INJURY
1University of Florida, Pediatric Critical Care, Gainesville, USA
2University of Florida, Emergency Medicine, Gainesville, USA
3University of Florida, Program for Neurotrauma, Neuroprotoemics & Biomarker Research, Gainesville, USA
4University of Florida, Pediatric Neurology, Gainesville, USA
Keywords: Pediatric, TBI, GFAP, Gender, Outcomes
TAU AS A POTENTIAL BIOMARKER FOR PROGNOSIS AND DIAGNOSIS OF PEDIATRIC TRAUMATIC BRAIN INJURY
1University of Florida, Pediatric Critical Care, Gainesville, USA
2University of Florida, Neurotrauma, Neuroprotoemics & Biomarker Research, Gainesville, USA
3University of Florida, Emergency Medicine, Gainesville, USA
4University of Florida, Pediatric Neurology, Gainesville, USA
Keywords: pediatric, tbi, tau, biomarker
COMBINED BLOOD‐BASED BIOMARKER PANEL OF MAJOR SUBPHENOTYPES OF PEDIATRIC TRAUMATIC BRAIN INJURY AND NEURODEVELOPMENTAL OUTCOMES
1University of Florida, Pediatric Critical Care, Gainesville, USA
2University of Florida, Pediatric Surgery, Gainesville, USA
3University of Florida, Emergency Medicine, Gainesville, USA
4University of Florida, Pediatric Neurology, Gainesville, USA
5University of Florida, Neurotrauma, Neuroprotoemics & Biomarker Research, Gainesville, USA
6University of Florida, Pediatric Neurosurgery, Gainesville, USA
Keywords: pediatric tbi, biomarkers, neurocognitive outcomes, mortality
AGE AND SEX‐DEPENDENT EFFECTS ON OUTCOME FOLLOWING A NOVEL, MIXED MODEL OF PEDIATRIC TBI
University of Iowa Carver College of Medicine, Pediatrics, Iowa City, USA
Age‐dependent biomechanical and pathophysiologic differences have been demonstrated following pediatric TBI, demanding greater use of pediatric TBI models in order to identify relevant therapeutic targets. In children with severe TBI, mixed focal and diffuse brain injury occurs commonly. The lateral FPI model induces mixed injury with both focal contusion and diffuse axonal injury. While lateral FPI has been adapted to juvenile rats, it has not been reported in juvenile mice limiting the genetic tools available for dissection of TBI pathophysiology. Adaptation of lateral FPI to juvenile mice is thus an important advance. Our primary objective was to determine if lateral FPI in juvenile mice represents a reproducible model of pediatric TBI with characteristic tissue injury, secondary injury response, and behavioral deficits. Additionally, we were interested in examining age‐ and sex‐dependent effects on outcome. Methods: A modification was made to the standard method of trephination allowing for successful left parietal craniectomy in 21 ± 3 day male and female juvenile C57BL/6J mice. Sham injury or lateral FPI was completed on the following day, targeting moderate‐severe injury. Gene expression, neuropathology, and neurobehavioral function were evaluated at various time points post‐TBI. Outcomes in juvenile mice were also compared to our historical data from adult mice exposed to the same severity of lateral FPI. Results: Average peak pressure of fluid pulse was 1.29 ATM resulting in a righting reflex of 11.8 ± 0.5 minutes. Juvenile lateral FPI resulted in DAI and cortical tissue loss. Rapid cytokine expression was seen in areas of focal and diffuse injury. Neurobehavioral consequences included motor and cognitive dysfunction. Age‐dependent differences in secondary neuroinflammation and neurologic outcome were observed. Juvenile mice also displayed sex differences in the inflammatory response and cognitive outcome following lateral FPI. Conclusions: Juvenile lateral FPI in mice represents a reproducible model of pediatric TBI. Further work will be done utilizing juvenile lateral FPI in mice to dissect the biologic effects of age and sex on TBI outcome. K12HD27748, K08NS110829
Keywords: Pediatric TBI
MULTIDISCIPLINARY REHABILITATION‐BASED CLINIC FOR CHILDREN WITH TRAUMATIC BRAIN INJURY
1University of Pittsburgh Medical Center, Department of Critical Care Medicine, Pittsburgh, USA
2University of Pittsburgh Medical Center, Department of Physical Medicine and Rehabilitation, Pittsburgh, USA
3UPMC Children's Hospital of Pittsburgh, The Brain Care Institute, Pittsbughh, USA
Keywords: TBI, Outcome, Multidisciplinary Clinic, Recovery
EFFECT OF A MILD TRAUMATIC BRAIN INJURY DURING ADOLESCENCE ON EXECUTIVE FUNCTION IN ADULTHOOD
1University of South Australia, Adelaide, Australia
2University of Adelaide, Adelaide, Australia
Adolescents have the highest rates of mild traumatic brain injury (mTBI) and respond differently compared to adults. Symptomatic recovery takes twice as long, and a higher percentage develop chronic symptoms such as impulsivity and difficulty concentrating. Vulnerability to mTBI in adolescence may relate to disruption of pre‐frontal cortex development, which is maturing throughout adolescence and is critical for development of executive functions including behavioural inhibition and attention. Gender also influences response to mTBI, with females proposed to have more neurologic deficits. This study investigated effects of mTBI in mid‐adolescence in male and female Sprague Dawley rats on executive functioning in adulthood via the 5‐choice serial reaction task (5‐CSRT). Animals at postnatal day 35 (n = 8 per group) were injured via weight drop (100g from 0.75m), with impact driving rats through foil onto foam to produce rotational forces. Injury was confirmed with significant increase in righting reflex in both genders (males 358.58 ± 50.98 vs 191.83 ± 65.67; females 323.5 ± 51.06 vs 185.37 ± 74.36, p < 0.05). Following training, at four weeks post‐injury animals undertook a series of 5‐CSRT probe trials, locating a stimulus in one of five potential locations. Probe 1 randomly varied inter‐trial interval; Probes 2‐4 gradually decreased stimulus duration (4, 2.5 and 1.5 sec). In Probe 1, mTBI males had a higher premature response rate relative to shams, reflecting increased impulsivity (22.28 ± 5.25 vs 12.32 ± 33 ± 5.88%, p < 0.05). This effect was not noted in females, but may relate to a higher premature response rate in female vs male shams (p = 0.08). No effects of injury or gender were noted in accuracy in Probes 2‐4, but injury regardless of gender led to increased omissions, most notably at 4 and 2.5, but not 1.5 sec stimulus duration. We found subtle gender specific deficits in executive function in early adulthood suggesting this is a critical period for maturation of executive function that may be disrupted by a mTBI.
Keywords: adolescence, executive function
B16 Post‐Traumatic Stress
SEX DIFFERENTIATION OF SPORT‐RELATED CONCUSSION IN JAPAN
Toho University Ohashi Medical Center, Department of Neurosurgery, Tokyo, Japan
The search period is April 2017 to February 2018. Inclusion criteria were as follows: 1) Sports‐related head injury cases, 2) Physician‐diagnosed Sports‐related concussion, 3) Underwent evaluation by the same neurosurgeon, 4) More than 28 days continued follow‐up. The following items were compared male and female. The examination items were as follows: 1) Age/sex, 2) competition item, 3) prior concussion, 4) Migraine history, 5) persistent post concussive symptoms. Statistical analysis used t test.
Keywords: sports‐related concussion, persistent post concussive symptoms
INCREASED PHONOPHOBIA AND CONTEXTUAL FEAR IN FEMALE RATS FOLLOWING FLUID PERCUSSION INJURY
1UCLA, Neurosurgery, Los Angeles, USA
2UCLA, Psychology, Los Angeles, USA
3UCLA, Steve Tisch BrainSPORT Program, Los Angeles, USA
4UCLA, Staglin Center for Brain and Behavioral Health, Los Angeles, USA
Traumatic brain injury (TBI) is a significant predictor for post traumatic stress disorder (PTSD). Prevalence of TBI is higher in males than females. However, females are 2‐4 times more likely to have PTSD. Sex differences in stress reactions and learning and memory may underlie differences in psychiatric comorbidities that emerge following TBI. We have shown that auditory white noise is noxious to male rats following fluid percussion injury (FPI) and increases fear learning when used in auditory fear conditioning, but it is unclear whether females exhibit a similar PTSD‐like phenotype. Adult female and male rats received either lateral FPI or sham surgery and 48h later received behavioral training. In this two part study, we first investigated sex differences in behavioral responses to white noise and noise‐shock fear conditioning and contextual recent and remote fear memory. Groups were pre‐exposed to white noise (75dB) the day before noise‐shock fear conditioning to the same stimulus. FPI groups exhibited defensive behavior to white noise, which was significantly more robust in females, suggesting FPI increased auditory sensitivity. After auditory fear conditioning, females overall had reduced recent and remote contextual fear. In experiment 2, we looked at whether FPI increases nonassociative fear after shock only conditioning in both sexes. FPI groups froze more following the first shock trial than sham and FPI groups also showed greater context fear, driven by the females. We saw little to no fear sensitization to a novel tone (75dB/2800Hz) in any group. Given that in general females display reduced contextual fear compared to males, our data suggest that females may be more affected by TBI as evidenced by greater phonophobia and context fear after FPI. These data demonstrate sex differences in emergent anxiety phenotypes following TBI that may contribute to comorbid PTSD.
Keywords: fear, hippocampus, amygdala, phonophobia, sex differences, female
A TALE OF TWO DATABASES: ALIGNING COMMON DATA ELEMENTS FOR POSTTRAUMATIC STRESS AND TRAUMATIC BRAIN INJURY
1University of Minnesota, Department of Psychiatry and Behavioral Sciences, Minneapolis, USA
2University of Minnesota, Institute for Health Informatics, Minneapolis, USA
3University of California San Francisco, Department of Veterans Affairs, San Francisco, USA
4University of Minnesota, Department of Medicine, Minneapolis, USA
Maladaptive complications following physical and psychological trauma, including traumatic brain injury (TBI) and posttraumatic stress (PTS), have been difficult to accurately diagnose, manage and treat. Recent efforts in computational psychiatry and TBI clinical research aim to harness multi‐dimensional data from clinical research studies and leverage machine learning approaches to identify “biotypes” of neuropsychiatric disorders. This study aims to identify common elements across TBI and PTS data, by mining the Federal Interagency Traumatic Brain Injury Research (FITBIR) informatics system (N = 4799), and the National Institute of Mental Health (NIMH) Data Archive (NDA, N = 310,256). We identified approximately 100 common elements among the 690 and 2815 different forms/assessments collected across both FITBIR and NDA, respectively. However, not all studies have shared data that is accessible to researchers, and only 27 of these assessments are fully congruent between the two repositories. Along with basic demographics and core common data elements, other overlapping assessments include measures of anxiety, depression, general psychiatric symptoms, cognitive function across multiple domains, alcohol use, PTSD symptoms, general health, sleep quality, satisfaction with life, and measures of intelligence. With these overlapping data elements, we will build a cross‐platform query tool to harness data across these two repositories to apply machine learning algorithms aimed at defining more precise “biotypes” of neurological trauma to tease out the distinct and overlapping features of TBI and PTS psychopathology.
Funded by NIMH R01 MH116156 (JLN).
Keywords: Computational Psychiatry
CHRONIC EFFECTS OF TBI ON LIMBIC CIRCUITRY, ANXIETY AND LEARNED FEAR BEHAVIORS
1University of Pennslyvania, Neurosurgery, Philadelphia, USA
2Corporal Michael J. Crescenz VA Medical Center, Philadelphia, USA
Traumatic Brain Injury (TBI) has been implicated in memory deficits and anxiety disorders such as Post‐Traumatic Stress Disorder (PTSD), and is commonly seen in veterens returing from combat. Previous studies investigating the effect of injury on limbic circuitry have found disruptions in entrainment of single units and in local field potential oscillations that organize neuronal ensembles. To determine how injury affects these limbic mechanisms and related changes in fear response, we subjected rats to a lateral fluid percussion injury (FPI) and chronically implanted high density silicon electrodes in the basolateral amygdala (BLA) as well as bipolar electrodes in medial prefrontal cortex (mPFC) and ventral hippocampus (vHC). We recorded during an anxiety behavior paradigm including elevated plus maze (PM), open field (OF), and fear conditioning (FC). The FC paradigm consisted of acquisition where rats learned to associate white noise (CS+) with a mild footshock, followed by two days of extinction, where rats were presented the white noise and a novel tone (CS‐) without the footshock. Both groups of animals acquired the fear response similarly, but FPI animals extinguished fear at a slower rate and showed a higher fear response on day 2 of extinction. Animals tested at 6 months post‐injury showed similar results, but displayed faster fear acquisition and slower extinction in both groups. We also found that FPI led to an increase in the strength of gamma oscillations (45‐110Hz) in BLA and mPFC‐BLA gamma coherence, both of which increased further after fear acquisition. FPI also caused an increase in phase‐amplitude coupling of BLA gamma to low frequencies in mPFC, which shifted to theta after acquisition. Additionally, we found that FPI led to a shift in entrainment of BLA neuron firing to local BLA theta. These changes in oscillations and spike‐timing may lead to altered fear learning following TBI.
Keywords: Amygdala, Hippocampus, Medial Prefrontal Cortex, Anxiety
ACUTE RESTRAINT STRESS EXACERBATES LONG‐TERM MALADAPTIVE MEMORY IN A MURINE MODEL OF TBI WITH DELAYED HYPOXEMIA
Washington University in St. Louis School of Medicine, Pediatrics, St Louis, USA
Maladaptive and abnormal fear memory has been associated with post‐traumatic stress disorder (PTSD), and altered hippocampal‐amygdala circuitry may be a contributing factor to such pathologic memory. Utilizing our previously developed clinically relevant murine model of TBI with delayed hypoxemia, we analyzed whether exposure to an acute stress remotely after injury could induce PTSD‐like memory impairment. Mice experienced controlled cortical impact or sham surgery followed by 1h of hypoxemia (8% O2 and 4% CO2) 24h after injury. We performed a three‐day contextual and cued fear conditioning behavioral paradigm at 1 or 3 months post injury in separate cohorts. Immediately after conditioning day (Day 1), mice were randomized to acute stress exposure, placing mice in a 50 mL ventilated falcon tube for 1h, or no stress. At one month post injury, injured animals regardless of stress exposure had increased freezing during contextual fear memory testing and increased freezing during non‐tone periods of cued fear memory compared to shams. However, there was no significant effect of restrained stress in fear memory in injured or sham animals. At 3 months post injury, there was a significant injury*stress interaction during cued fear memory testing (p = 0.036) with injured animals exposed to acute stress freezing more during tone periods. Interestingly, there was no significant injury*stress effect observed during contextual fear memory testing. Our data shows that when injured mice with delayed hypoxemia are exposed to restrained stress 3 months post injury, they exhibit a PTSD‐like maladaptive fear memory response. We hypothesize that an imbalance between excitatory and inhibitory neurons may be responsible for these PTSD‐like memory impairments. Elucidating the underlying pathology involved with abnormal fear response after TBI may provide a unique opportunity to better develop therapeutics that target clinically relevant long‐term psychological dysfunction for TBI survivors.
Keywords: restraint stress, maladaptive fear memory, traumatic brain injury, delayed hypoxemia, contextual and cue fear conditioning
B17 Regeneration & Plasticity
PROLONGED NEUROMODULATION AFTER EXPERIMENTAL TBI ENHANCES FUNCTIONAL CONNECTIVITY BUT DOES NOT IMPROVE EVOKED ACTIVATION
UCLA, Neurosurgery, Brain Injury Research Center, Los Angeles, USA
Functional connectivity changes occur after TBI in humans and animal models. We hypothesize that development of hyperexcitability after injury within homotopic cortical regions contralateral to the primary injury site, results in increased trans‐hemispheric inhibition that prevents reorganization of the primary injured hemisphere. To determine the effect of long‐term silencing of contralesional cortex on reorganization of brain circuits, we acquired forelimb‐evoked‐fMRI and resting‐state‐fMRI at 4 and 8wks post‐injury after continuous infusion of muscimol into the contralesional sensory‐motor cortex for 4wks immediately following CCI injury, and compared the data to vehicle‐infused‐injured and sham rats (n = 6,5,6). Forelimb‐evoked brain activation and network‐based functional connectivity (fc) were calculated. The ladder‐walk task at 1wk post‐injury confirmed brain silencing as indicated by increased number of faults of the limb opposite to the muscimol‐injected, contralesional cortex. However, to our surprise, increased evoked activation from the same forelimb 3wks later indicated the development of increased contralesional hyperexcitability above that in the vehicle‐treated, injured rats (P < 0.001, z > 2.3 cluster‐corrected), but not at 8wks post‐injury, 4wks after the end of muscimol infusion. There was no change in brain activation within the ipsilesional hemisphere evoked by the injury‐affected limb stimulation at either time‐point, indicating that either the period of silencing was not optimal to enhance ipsilateral brain function, and/or, that the unexpected, neuromodulatory‐induced hyperexcitation nulled any potentially positive effects. We evaluated the impact of hyperexcitability on fc after TBI in the same rats and found the expected bilateral decrease within and between the cortical hemispheres at 4wks due to muscimol, indicating cortical isolation (P < 0.05, FDR‐corrected q = 0.05). However, this was followed at 8wks by a significant, bilateral increase in local fc, especially in ipsilateral forelimb circuits, as well as across the brain when compared to vehicle‐treated, injured rats. Differences in outcome between the evoked‐activation and resting‐state circuit analysis indicate some persistent neuromodulatory effects, but that the parameters of neuromodulation remain to be optimized.
Acknowledgements: UCLA Brain‐Injury‐Research‐Center; NIH‐NINDS R01NS091222
Keywords: Traumatic Brain Injury, Reorganization, long‐term silencing of contralesional cortex, rsfMRI, Functional Connectivity, forelimb stimulation‐induced fMRI
TRAUMATIC STRESS DYNAMICALLY ALTERS INHIBITORY PROCESSES IN LIMBIC AREAS AFTER TRAUMATIC BRAIN INJURY
1UCLA, Neurosurgery, Los Angeles, USA
2UCLA, Psychology, Los Angeles, USA
3UCLA, Steve Tisch BrainSPORT, Los Angeles, USA
4UCLA, Mattel Children's Hospital, Los Angeles, USA
5UCLA, Psychiatry & Biobehavioral Sciences, Los Angeles, USA
6UCLA, Staglin Center for Brain Behavioral Health, Los Angeles, USA
Traumatic brain injury (TBI) is often comorbid with psychological mood and trauma related disorders, such as post‐traumatic stress disorder (PTSD) but the biological mechanisms for this association are not well understood. We previously investigated the effects of TBI on neuronal plasticity within the first week after fluid percussion injury (FPI) and found post‐injury dysregulation in both the dorsal hippocampus (DH) and basolateral amygdala (BLA). In this study we asked whether an emotional stressor exposure would affect these disrupted networks after FPI. To determine the effect of TBI and behavioral trauma on GABA in bilateral DH and BLA, 48h after lateral FPI or sham surgery, rats received auditory fear conditioning or were left undisturbed. We measured levels of the GABA synthetic proteins, glutamate decarboxylase (GAD67, GAD65) 6h after conditioning via western blotting. In the DH, FPI led to an overall decrease of GAD65 (p < 0.01). In the BLA, a fear conditioning by injury group interaction revealed that in shams only, fear conditioning resulted in significant upregulation of GAD65 (p = 0.04), suggesting a changed response to stress in FPI groups. These data demonstrate that the inhibitory mechanisms involved in learning and affective processing which are dysregulated after TBI, are further affected as a result of traumatic stress. Understanding the alterations of inhibitory proteins in the limbic system after TBI and traumatic stress may provide insight into mechanisms disrupting fear learning and memory processes after injury. This work was supported in part by Avanir Pharmaceuticals, Inc.: CG, AH; F32S098694: AH; UCLA Brain Injury Research Center; 1RO1NS27544: DH, CG; UCLA Easton Labs for Brain Health, UCLA Steve Tisch BrainSPORT Program: CG, SW, AH.
Keywords: Glutamatergic, GABAergic, Excitatory, Inhibitory
HARNESSING RETRO‐AAV TO ASSESS DE NOVO GROWTH OF ADULT CORTICAL NEURONS FOLLOWING PTEN DELETION
University of California, Irvine, Anatomy and Neurobiology, Irvine, USA
The mammalian target of rapamycin (mTOR) pathway is a major regulator of cell growth and proliferation, with phosphatase and tensin homolog (PTEN) being a key negative regulator of its activity. Past studies have shown that deletion or knockdown of PTEN enables axon regeneration following both optic nerve and spinal cord injury. Although early embryonic deletion of PTEN results in brain hypertrophy and seizures, no adverse effects have been seen with PTEN deletion in adult rodents. Recently, our lab has shown that direct cortical PTEN deletion in adult mice triggers de novo growth of cortical neuron cell bodies and increased dendritic arborization. Here, we utilized a remarkable new technology involving AAV vectors that are transported retrogradely from axons to neuronal cell bodies (retro‐AAV). When injected into the spinal cord, retro‐AAV is transported back to the cell bodies of cortical neurons that give rise to the corticospinal tract (CST). Specifically, retro AAV‐Cre was injected into the spinal cord at cervical level 5 (C5) in transgenic mice with floxed PTEN and a Cre‐dependent reporter gene, stop‐flox tdTomato (tdT). In these mice, transfection with AAV‐Cre results in deletion of PTEN and expression of tdT in the same neurons. Controls were transgenic tdT reporter mice. In both strains, thousands of cortical motoneurons are transfected as evidenced by expression of tdT. Immunostaining reveals effective deletion of PTEN in retrogradely transfected neurons in PTEN/tdT mice with continued PTEN expression in tdT controls. Preliminary results reveal increases in cell body and nuclear size and assessment of locomotor function on the Rotorod reveals no differences between PTEN‐deleted and control groups. Our preliminary findings demonstrate that PTEN deletion can induce growth in pyramidal motor neurons of adult mice without causing any significant impairments in motor learning. Further characterization will allow for better understanding of the role of PTEN in neuronal morphology and plasticity and insights into the therapeutic potential of this intervention following injury.
Keywords: PTEN, retrograde AAV, mTOR, corticospinal tract
A TISSUE ENGINEERED ROSTRAL MIGRATORY STREAM FOR DIRECTED NEURONAL REPLACEMENT FOLLOWING BRAIN INJURY
1CMJC VA Medical Center, Center for Neurotrauma, Neurodegeneration & Restoration, Philadelphia, USA
2University of Pennsylvania, Center for Brain Injury & Repair, Department of Neurosurgery, Philadelphia, USA
3University of Pennsylvania, Department of Oral and Maxillofacial Surgery and Pharmacology, Philadelphia, USA
Neuroregeneration post‐injury is hindered by a dearth of new neurons in the mature brain. Neurogenesis in adults is limited to the subventricular zone (SVZ) and dentate gyrus. The rostral migratory stream (RMS) facilitates migration of neuroblasts from the SVZ to the olfactory bulb, where they replace lost neurons. In some cases, injury results in migration of neuroblasts out of the RMS toward affected areas, but this response is insufficient. We have developed techniques for fabricating aligned astrocytic bundles mimicking the organization of the glial tube at the core structure of the RMS. This Tissue‐Engineered RMS (TE‐RMS) provides a “living scaffold” to redirect endogenous neuroblasts from the SVZ into distal brain lesions. TE‐RMSs were created using a biomaterial encasement scheme to induce astrocytes to self‐assemble into dense bundles of bipolar, longitudinally‐aligned astrocytes, just 150 microns in diameter yet extending several centimeters long. The TE‐RMS reflects the morphology and protein expression of the glial tube, and directly facilitates migration of immature neurons in vitro. In an exciting recent development, our team has recently developed a protocol for deriving astrocytes from human gingiva stem cells, providing a minimally‐invasive means to create patient‐specific TE‐RMSs. Finally, TE‐RMSs fabricated from deidentified human stem cell‐derived astrocytes were implanted in athymic rat brains and facilitated migration of endogenous neuroblasts out of the native RMS and through the TE‐RMS. By enhancing the brain's endogenous injury response through emulation of the brain's most efficient means for directing neuroblast migration, the TE‐RMS offers a promising new approach to neuroregenerative medicine. Future work will focus on testing the effects of TE‐RMS implantation on regeneration and recovery after brain injury.
Keywords: Tissue‐engineering, Bioengineering, rostral migratory stream, Neuroregeneration, Neuroblast, glial tube
WIDESPREAD DENDRITIC PATHOLOGY IS EVIDENT FOLLOWING SEVERE PENETRATING BRAIN INJURY IN RATS
WRAIR, Brain Trauma Neuroprotection Branch, Center for Military Psychiatry and Neuroscience, Silver Spring, USA
Traumatic brain injury (TBI) has been shown to induce extensive dendritic pathology. Increasing evidence suggests that damaged dendrite and spines directly affect synaptic plasticity, which plays a critical role in neuronal function and behavioral modulation. The current study was designed to define the temporal and regional alterations in neuronal morphology and dendritic loss in the penetrating ballistic‐like brain injury (PBBI) model. Adult Sprague‐Dawley rats were subjected to PBBI (10% injury, n = 8/group) or sham craniotomy (n = 4/group) and euthanized at 1, 2, 3, 7, 14 or 28 days post‐injury. Assessment and quantitation of dendritic injury was done using Golgi and microtubule associated protein‐2 (MAP‐2) staining. For dendritic Sholl analysis, Golgi stained neuronal images were analyzed using Fiji Sholl analysis plugin for ImageJ. MAP‐2 immunostaining intensity was quantified separately from cortex and hippocampus using ImageJ. The injury core was devoid of Golgi stained neurons and neurons in the injury penumbra showed reduced dendritic branching complexity. Significant changes in various Sholl parameters including number of intersections, maximum radius and Schoenen Ramification Index (SRI), were observed following PBBI at the majority of post‐injury time points studied. We also observed dendritic beading/blebbing in penumbral neurons indicating the presence of degenerating dendrites. Reduced MAP‐2 staining was seen in the cortex at acute time points following severe brain injury, demonstrating loss of neurites. Employing Golgi staining coupled with Sholl analysis we have been able to identify several morphological changes in neurons following PBBI. Extensive trauma induced alterations in dendrites show that these changes may underlie neurological symptoms following TBI. Moreover, loss of MAP‐2 staining even in areas distal to the injury core indicate that dendritic derangement is widespread following PBBI, and may contribute to post‐traumatic behavioral dysfunction. Further studies in PBBI model will utilize therapeutic approaches to protect spared neural dendrites and spines in an effort to mitigate functional abnormalities following severe TBI.
Keywords: Golgi stain, dendrites, MAP‐2, TBI
B18 Secondary Injury
TOWARDS AN AUTOMATED ALGORITHM FOR DETECTION OF CORTICAL SPREADING DEPRESSION BASED ON ELECTROCORTICOGRAPHY SIGNALS
Keerthana Gurushankar1,
1Carnegie Mellon University, ECE, Pittsburgh, USA
2University of Pittsburgh/UPMC Healthcare System, Department of Emergency Medicine and Critical Care Medicine, Pittsburgh, USA
3University of Pittsburgh/UPMC Healthcare System, Department of Critical Care Medicine, Neurology and Neurosurgery, Pittsburgh, USA
4University of Cincinnati, Neurosurgery, Cincinnati, USA
Keywords: Cortical Spreading Depression (CSD), Traumatic Brain Injury (TBI), Electrocorticography (ECoG), Automated detection, Stroke
DELETION OF SYNTAPHILIN IS NEUROPROTECTIVE AND IMPROVES BEHAVIORAL RECOVERY AFTER SPINAL CORD INJURY
Indiana University School of Medicine, Neurological Surgery, Indianapolis, USA
Traumatic spinal cord injury (SCI) is prevalent worldwide with limited treatments available. Understanding molecular mechanisms that underlie functional deficits associated with SCI and developing new repair strategies for it are urgent medical needs. Mitochondrial dysfunction has been implicated in the secondary neuronal injury following SCI. Recent evidence showed that knocking down mitochondria‐anchoring protein syntaphilin (SNPH) enhanced mitochondrial transport, and led to removing stressed mitochondria, rescuing energy deficits, and promoting axon regeneration. However, whether SNPH deletion has a neuroprotective effect after SCI remains unclear. In this study, we explored such possibility in a clinically relevant model of contusive SCI. In this study, SNPH knockout (KO) mice and wild‐type (WT) littermates (12 weeks, 18–24g) underwent a T10 contusion using an Infinite Horizon impactor (Lexington, KY) at an impact force of 60 kdyne. All assessments were blindly performed. After injury, the Basso Mouse Scale (BMS) locomotor test was performed weekly up to 6 weeks, and grid walking test was performed at 4 and 6 weeks. Histological analysis was performed at 6 weeks postinjury using Cresyl violet and eosin staining. Prior to the injury, behavioral baseline assessments showed no difference in motor and sensory functions between SNPH KO and WT mice. After SCI, the BMS locomotor scores were significantly improved in SNPH KO mice (p < 0.05–0.01) for up to 6 weeks as compared to WT littermates. The grid walking test showed a significant improvement in SNPH KO mice (p < 0.05–0.01) at 4 and 6 weeks post‐SCI as compared to WT littermates. Histological analysis revealed a significant reduction of tissue damage (p < 0.01) in SNPH KO mice as compared to WT littermates. These findings collectively suggest that blocking SNPH is neuroprotective, and as such could be an attractive therapeutic approach for ameliorating secondary SCI.
Keywords: Spinal cord injury, Mitochondria‐anchoring protein syntaphilin, Neuroprotection, Behavioral recovery
CEREBRAL BLOOD FLOW IS REDUCED DURING AEROMEDICAL EVACUATION‐RELEVANT HYPOBARIA FOLLOWING RAT TRAUMATIC BRAIN INJURY
Univ. of Maryland School of Medicine, Anesthesiology, Baltimore, USA
Simulated aeromedical evacuation (AE), or hypobaria equal to 8000 ft cabin pressure, worsens neurologic and neuropathologic outcomes after TBI; however, the underlying mechanisms responsible for this form of secondary brain injury are unknown. Magnetic resonance imaging and spectroscopy measurements were performed on control cortical impact (CCI) injured male rats before, during and after exposure to simulated AE in a MRI compatible, custom built hypobaric chamber. A 6 hr “flight” initiated at 24 hr after CCI injury was conducted under normobaric (sea level) or hypobaric cabin pressure and under normoxic (30‐40% O2) or hyperoxic (100% O2) conditions. Pulsed continuous arterial spin labeling experiments revealed a hypobaria‐induced, acute reduction in cerebral blood flow (CBF) in the ipsilateral and contralateral cortex, thalamus and hippocampus. Single voxel proton spectra were obtained from the ipsilateral and contralateral cortex measuring absolute concentrations of multiple metabolites. Ipsilateral cortical glutathione levels dropped by approximately 50% within one day after injury but increased with subsequent exposure to hypobaria under normoxic and hyperoxic conditions. Lactate levels increased by 8‐fold following CCI, remained elevated during all AE and returned to baseline by 14 dpi. Exposure to normobaria under 100% O2 resulted in further increase compared to hypobaric counterparts. Cortical hyperintensity volumes quantified from T2‐weighted images show an increase due to CCI and further increase only when AE occurred under normobaric conditions under 100% oxygen. The primary conclusion from these measurements is that exposure to AE‐relevant hypobaria one day after moderate TBI reduces CBF in the cortex and in brain locations distal from the primary injury. Experiments are in progress to determine if this effect is due to elevated intracerebral pressure. These and other TBI/hypobaria studies suggest that it would be safer to avoid flying soon after TBI. Supported by US Air Force FA8650‐17‐2‐6H13
Keywords: hypobaria, hyperoxia, magnetic resonance spectroscopy, magnetic resonance imaging
NEUROGENIC SHOCK TREATMENT EFFECTIVENESS IN THE EMERGENCY DEPARTMENT ‐ THE NEED FOR A CODE SCI
University of California San Francisco, Emergency Medicine ‐ Track SCI, San francisco, USA
The optimal mean arterial blood pressure (MAP) for maintenance of spinal cord perfusion in the first four hours following spinal cord injury (SCI) is not known. Data from ICU patients suggests using vasopressors instead of fluids to obtain a MAP goal of 75‐85 for 7 days post injury in patients with no known ongoing hemorrhage. Our aim was to identify and evaluate treatment of blunt non‐hemorrhagic shock SCI patients (SBP <100) at the earliest time points in a Level 1 Emergency Department. Methods: Retrospective cohort study (2005‐2015) of 212 patients with SCI. 93 patients with blunt injury mechanism without evidence of hemorrhage. Results: Total time in ED was 229 minutes. 49.4 percent of SCI patients experienced non‐hemorrhagic presumed neurogenic shock (Systolic BP <100) (45 minutes) in the ED. Mean Arterial Blood Pressure (MAP) goals (MAP >85) were not met in 80% of patients (156 minutes). Injury Severity Score (ISS) and initial ASIA grade were each significant predictors of hypotension (p = .011 & p = .003). Only 50% of shock patients were bradycardic (HR <60). All patients received IV Normal Saline (1.3 liters) but treatment with IV fluids alone did not effectively treat hypotension or improve MAP goal compliance. Conclusions: Approximately half of blunt trauma SCI patients experience ongoing non‐hemorrhagic shock during a significant portion of their Emergency Department evaluation. Despite guidelines associating hypotension with worsening outcomes, patients remained hypotensive after fluids and had delays in pressor initiation. Acute ED Stroke management has shown that ultra‐early treatment including MAP control is possible within minutes suggesting the need for a “Code SCI” to aggressively treat neurogenic shock.
Keywords: neurogenic shock, emergency department, ischemia, vasopressors
CYCLIN D1 AND NRF1 INTERACTION AFFECTS MITOCHONDRIAL MASS FOLLOWING TRAUMATIC BRAIN INJURY
University of Pittsburgh Medical Center, Department of Neurological Surgery, Pittsburgh, USA
CyclinD1 is a key component of cell cycle activation and regulates cell cycle progression through phosphorylating various substrates. Despite its well characterized classical functions in cell cycle regulation, a set of new functions including inhibition of mitochondrial metabolism have recently been identified. Aberrant cell cycle activation along with CyclinD1 upregulation has been reported in several neurological disorders including traumatic brain injury (TBI). In addition, mitochondrial mass which is a critical indicator of mitochondrial health, has also been found to be impaired in injured brain tissues. However, the underlying mechanism of how TBI leads to impairment of mitochondrial mass following TBI remains obscure. The transcription factor, nuclear respiratory factor 1 (NRF1), regulates different signal cascades that determine mitochondrial mass and therefore the function. Moreover, CyclinD1 has a negative impact on NRF1 function. In our present study, we sought to identify whether CyclinD1 has any effect on NRF1 and thereafter the impairment of mitochondrial mass in TBI brain. Our results indicate that, augmentation of CyclinD1 attenuates mitochondrial mass formation following TBI in mice brain cortex. In order to identify the molecular mechanism, we found that CyclinD1 interacts with NRF1 in nucleus and prevents its interaction with p300 following TBI. As a result, p300 mediated acetylation of NRF1 is decreased and the deacetylated NRF1 becomes transcriptionally inactive. Therefore TFAM, a downstream target of NRF1, has been found to be downregulated upon TBI condition. This phenomenon leads to a loss of mitochondrial mass following TBI. Finally, intranasal delivery of CyclinD1 RNAi after TBI, rescues transcriptional activation of NRF1 through restoring its interaction with p300 acetyltransferase and increased expression of TFAM. Eventually, mitochondrial mass has also been found to be restored after TBI by RNAi mediated CyclinD1 knockdown. So taken together, our study unravel a molecular mechanism of how CyclinD1 mediates impairment of mitochondrial mass by interacting with NRF1 upon TBI in mice brain cortex.
Keywords: CyclinD1, TBI, Mitochondrial dysfunction
PREDICTING NEUROSURGICAL CLEARANCE IN THE PATIENT WITH POLYTRAUMA AND CONCOMITANT TRAUMATIC BRAIN INJURY
University of South Florida, Neurosurgery, Tampa, USA
Neurosurgeons are faced with the dilemma of providing clearance for a polytrauma with traumatic brain injury (TBI) patient to undergo non‐cranial surgery. Current prognostic scores are used as predictors of long‐term outcome for TBI patients, however, there is a need to create a model to predict the likelihood of stability during a non‐cranial surgery in a polytrauma with TBI patient in the acute setting. We aimed to develop a prognostic model based on previously used predictors of prognosis in TBI patients to determine the likelihood of neurologic clearance for non‐cranial surgery. Polytrauma patients with concomitant TBI who presented to Tampa General Hospital (TGH) from July 2016 to December 2017 were included in the study. The data was recorded longitudinally from admission. The neurologic stability of the patient was assessed daily by noting a worsening, improvement, or stability in the patient's Glascow coma scale (GCS), CT scan, or tier of intracranial pressure (ICP) management. We developed a statistical model using the clinical measures of GCS, CT score, and tier of ICP management. Our model suggests that the relative importance of GCS, ICP and CT score in predicting clearance for surgery in polytrauma patients changes significantly with time. While GCS and CT scan are major determinants in the initial 24 hours, their importance lessens over time, and eventually becomes secondary to the ICP treatment tier. The preliminary model can be used to develop an algorithm to predict stability of neurologic status after extra‐cranial surgery in the polytrauma patient with TBI.
Keywords: polytrauma, outcome, predictive score
ALTERATIONS IN BRAIN MICRORNA EXPRESSION FOLLOWING CLOSED‐HEAD CONCUSSIVE INJURY
WRAIR, Brain Trauma Neuroprotection Branch, Center for Military Psychiatry and Neuroscience, Silver Spring, USA
MicroRNAs (miRNA) are small non‐coding RNAs that regulate gene expression and miRNA profiling is commonly used to screen biomarkers and identify novel therapeutic targets. Changes in miRNA expression have been observed following traumatic brain injury (TBI). The aim of the current study was to characterize regional and temporal changes in brain enriched miRNAs following both single and repeated concussion. Adult male Sprague‐Dawley rats were subjected to either single concussion (n = 10/time point) or repeated concussion (n = 10/time point) with appropriate sham controls (n = 5/group). Brain tissue from both the ipsilateral cortex and the hippocampus was collected at 24h, 72h, 7 days, 14 days, or 28 days post‐injury. Real‐time quantitative PCRs were carried out for 756 miRNA sequences of interest using TaqMan® OpenArray® miRNA panels. The relative level of expression, relative quantitation (RQ), was calculated using the following formula, RQ = 2‐ΔΔCRT. Differences between groups were evaluated after the data met the following criteria: CRT ≤35, AMPSCORE ≥1.24. Further assessment of the data was performed using Ingenuity Pathway Analysis (IPA) using miRNAs showing significant differences between groups (p ≤ 0.05). We detected temporal changes across 58 microRNAs in the cortex and 75 microRNAs in the hippocampus as a result of single or repeated concussion. Single concussions altered fewer (∼20) microRNAs in the cortex and hippocampus across all the time points studied whereas repeated concussions produced a greater number of alterations in microRNAs (∼50) in both regions. A comparative analysis across all the time points showed that 14 of these miRNAs are common between single and repeated concussion in the cortex and 8 in the hippocampus. Potential connections generated using IPA recognized 157 target molecules associated with TBI pathology. Further analysis revealed that the significantly altered microRNAs are predicted to target candidate genes playing vital roles in long term potentiation/depression, learning and memory, focal epilepsy, schizophrenia, speech disorders and general cognitive disability.
Keywords: microRNA, repeated concussion, mild TBI, gene expression
B19 Sleep
DISRUPTION IN SLEEP ARCHITECTURE IS ASSOCIATED WITH COGNITIVE OUTCOME AND QUALITY OF LIFE AFTER TBI IN A SEX DEPENDENT MANNER
Centre for NeuroSkills, Encino, USA
Those that endured a TBI frequently report problems with sleep and diurnal somnolence. After determining if subjective somnolence was associated with sleep disturbances, we investigated if alterations in sleep architecture were associated with cognitive, social and emotional health in a sex dependent manner. Given that some patients are receiving positive airway pressure (PAP) treatment, we also determined if lack of compliance contributed to cognitive and quality of life issues.
Keywords: sleep, apnea, outcome, traumatic brain injury
SLEEPINESS ALTERS GENE EXPRESSION IN MILITARY PERSONNEL AND VETERANS WITH TBI AND PTSD
1NIH, NINR, Bethesda, USA
2Henry M. Jackson Foundation for the Advancement of Military Medicine, Bethesda, USA
3Yotta Biomed, Bethesda, USA
4CNRM, Rockville, USA
5USUHS, Department of Medicine, Bethesda, USA
TBI with concurrent PTSD is pervasive in military personnel and veterans. A common symptom of both TBIs and PTSD is disturbed sleep. Up to 91% of military personnel and veterans with PTSD report co‐occurring sleep disturbances. Sleep disturbances have been shown to exacerbate PTSD, and increase risk of developing PTSD. The aim of this study was to examine gene expression in military personnel and veterans with TBI and PTSD, with and without sleep problems. Participants were categorized into two groups; 1) TBI+, PTSD+, with sleepiness (s_TBI_PTSD; n = 21), 2) TBI+, PTSD+, without sleepiness (nos_TBI_PTSD; n = 25).
Keywords: PTSD, RNA, Military, Veterans
SPECIFIC SLEEP DISORDER TARGETED INTERVENTION THERAPY IMPACT ON SLEEP QUALITY AND SATISFACTION WITH LIFE SCALE: A TEAM‐TBI STUDY
University of Pittsburgh, Neurological Surgery, Pittsburgh, USA
Keywords: Targeted, Therapy, Satisfaction, Sleep‐disorder
B20 Vascular
LOWER BODY NEGATIVE PRESSURE: A PRE‐CLINICAL MODEL OF ORTHOSTATIC HYPOTENSION FOLLOWING SPINAL CORD INJURY
1International Collaboration on Repair Discoveries, Vancouver, Canada
2University of British Columbia, Department of Medicine, Vancouver, Canada
Spinal Cord Injury (SCI) is a devastating condition that permanently impacts quality of life. Majority of individuals with cervical or high thoracic SCI suffer from debilitating cardiovascular impairments that are the leading cause of disability and death among this population. On daily basis, a common challenge faced by individuals with SCI is of unstable blood pressure (BP) control. During assumption of an upright posture from a supine position, the BP drops to abnormally low levels, a condition called orthostatic hypotension (OH). The BP during OH can fall to dangerously low levels (even below 50 mmHg) and often results in blurred vision, dizziness, loss of consciousness, cognitive deficits, and an elevated risk of stroke. Occurrence of OH during standard rehabilitation procedures decreases the ability of individuals with SCI to participate in rehabilitation interventions. Despite OH leading to alarming increases in morbidity and mortality following SCI, there remains to be limited knowledge on therapeutic approaches for its management and prevention. This is due in part to the difficulty of generating an animal model of OH after SCI. We present lower‐body negative pressure (LBNP) as a robust and clinically‐relevant animal model of OH. Using a well‐characterized rat model of T3 SCI, we evaluated the efficacy of LBNP to reduce BP. At 8 weeks post‐SCI, a wireless pressure transducer was implanted into the femoral artery. The lower body of the anesthetized animal was placed in the LBNP chamber connected to a vacuum source. The basal mean arterial pressure was recorded. Consistent with the clinical definition of OH, we observed a LBNP‐induced decrease of 20.2 ± 6.0 mmHg and 15.1 ± 5.1 mmHg in systolic and diastolic BP, respectively. These findings suggest that an LBNP chamber may be a valuable tool to test the efficacy of various treatment strategies for mitigating OH.
Keywords: Orthostatic Hypotension, Lower‐Body Negative Pressure Chamber, Pre‐Clinical, Systolic Blood Pressure, Diastolic Blood Pressure
A NON‐INVASIVE NEUROPROSTHESIS FOR CARDIOVASCULAR RECOVERY AFTER SPINAL CORD INJURY
International Collaboration on Repair Discoveries (ICORD), University of British Columbia, Medicine, Vancouver, Canada
Keywords: Spinal Cord Injury, Autonomic Dysreflexia, Transcutaneous Spinal Cord Stimulation
SEX DIFFERENCES IN VASCULAR DENSITY AND MOTOR OUTCOMES IN RATS GIVEN A TRAUMATIC BRAIN INJURY
1Monash Univeristy, Neuroscience & Medicine, Melbourne, Australia
2University of Melbourne, Medicine, Melbourne, Australia
The mechanisms that underlie potential sex differences in traumatic brain injury (TBI) outcomes remain unclear. Changes in vascular density and other measures of new blood vessel growth (i.e., angiogenesis) play a role in recovery post‐TBI. It is unknown if there are sex differences in injury induced changes in vessel density post‐TBI. The objective of this study was to test the hypothesis that females would have greater vessel density post‐TBI than males, and that this would be associated with improved recovery. Adult male and female rats were subjected to a severe TBI using a fluid percussion injury model. Steady‐state contrast enhanced MRI (SSC‐MRI, 15 mg/kg of ferumoxytol) was used to assess injured cortex vessel density in vivo 48 hours post‐injury. Motor coordination was assessed one week post‐injury using the balance beam. Male rats given a TBI were found to have longer traverse times and more slips/falls on a beam task when compared to their female counterparts (p < 0.05), while no statistical differences were found between sham males and sham females (p > 0.05). In regards to the SSC‐MRI results, TBI males had a significant decrease in vessel density as compared to TBI females as well as the sham‐injured groups. Moreover, the TBI females did not have a significant difference in vessel density as compared to sham‐injured females (p > 0.05). The greater vessel density in TBI females as compared to TBI males may have contributed to sex differences in motor coordination post‐TBI. SSC‐MRI could be used in future clinical studies in order to elucidate the temporal changes in cortical vessel density post‐TBI. A better understanding of sex differences in vascular responses post‐injury could aide in ensuring that the development of therapies targeting angiogenesis post‐TBI will be appropriate for both male and female patients.
Keywords: rat, behavior, sex difference, female, MRI, angiogenesis
CORRELATION BETWEEN POST TRAUMATIC HEADACHE AND TRAUMATIC CEREBROVASCULAR INJURY
Franck Amyot2,
1USUHS, Neurology, Bethesda, USA
2Walter Reed National Military Medical Center, National Intrepid Center of Excellence, Bethesda, USA
3University of Pennsylvania Perelman School of Medicine, Neurology, Philadelphia, USA
4National Insitutes of Health, Department of Rehabilitation, Bethesda, USA
5National Institutes of Health, National Institutes of Neurological Disorders and Stroke, Bethesda, USA
Keywords: Vascular injury, Post traumatic headache, cerebrovascular reactivity
Pre-Conference Bio
BIO2 Pre‐Conference II: Fluid‐Based Biomarkers for Precision Medicine Applications Assessing Function in NeuroTrauma Populations
DATA DRIVEN APPROACHES FOR SYNDROMIC BIOMARKERS IN THE LABORATORY AND CLINIC
University of California, San Francisco, Neurological Surgery, San Francisco, USA
The complex and heterogeneous nature of traumatic brain injury (TBI) has rendered the identification of diagnostic and prognostic biomarkers elusive. A single acute biomarker may not be sufficient to categorize injury severity and/or predict outcome. Using multivariate dimension reduction analyses, we tested the sensitivity and specificity of a multianalyte panel of proteins as an ensemble biomarker for TBI. Serum was collected within 24 hours of injury in a cohort of 130 patients enrolled in the Transforming Research and Clinical Knowledge in Traumatic Brain Injury (TRACK‐TBI) prospective pilot trial, and run on an array that measured 72 proteins. Using unsupervised principal components analysis we first identified the subset of proteins accounting for the most variance across patients. This yielded a group of 21 proteins that reflected an inverse relationship between inflammatory cytokines and regulators of anti‐inflammation, and generated an individual inflammatory profile score for each patient. We then tested the association between these scores and CT findings at hospital admission, as well as their prognostic association with functional recovery measures at 3 and 6 months (Glasgow Outcome Scale‐Extended) and cognitive recovery at 6 months (California Verbal Learning Test) after injury. Inflammatory signatures were significantly increased in patients with positive CT findings, as well as in those that showed poor or incomplete recovery. Inflammation biomarker scores also showed significant sensitivity and specificity as a discriminator of these outcome measures (all AUCs >0.62). This proof‐of‐concept for the feasibility of multivariate biomarker identification demonstrates the prognostic validity of using a proteomic panel as a potential biomarker for TBI.
Keywords: Biomarker, TBI, Multivariate
AANS CNS Sessions
CNS5 AANS/CNS Session 5: Controversies in Brain Injury
CONTROVERSIES IN BRAIN INJURY ‐ PRECLINICAL DATA HELPS
Safar Center, Univ of Pittsburgh, Critical Care Medicine, Pittsburgh, USA
Despite considerable support for therapeutic efficacy for a number of acute therapies targeting traumatic brain injury (TBI) in pre‐clinical studies in individual laboratories, there has been a failure of translation to successful clinical trials. Many explanations for this have been suggested, with concerns raised with regard to both the pre‐clinical and clinical investigations. In an attempt to address this translation failure, we developed Operation Brain Trauma Therapy (OBTT), a multicenter pre‐clinical therapy and biomarker screening consortium for severe TBI. The approach taken by OBTT has attempted to target two of the perceived major limitations in preclinical research; 1) the need to test drugs simultaneously across multiple models, in order to address the multiple TBI endophenotypes that are identified clinically on imaging, and 2) the need for a higher level of rigor in carrying out pre‐clinical therapy screening. OBTT has screened 12 therapies (nicotinamide, erythropoietin, cyclosporine, simvastatin, levetiracetam, glibenclamide, Kollidon VA‐64, AER‐271, amantadine, minocycline, E64d and P7C3‐A20) in >1500 rats across three TBI models (parasagittal fluid percussion [FPI], controlled cortical impact [CCI], and penetrating ballistic‐like brain injury [PBBI]). We assigned 22‐points per model across behavioral and histological outcomes, generating an overall score for each therapy. Two therapies, levetiracetam and glibenclamide ranked the highest. Only levetiracetam showed efficacy in multiple models. Glibenclamide showed marked model dependence, with efficacy largely restricted to CCI—suggesting potential use in contusion. Thus, precision‐based clinical trials may be needed and could be directed by a pre‐clinical multi‐model screening approach. Another potentially important finding from OBTT is that the pre‐clinical literature may be overly optimistic. We conclude that although there are many challenges to successfully carrying out rigorous pre‐clinical therapy screening, the work of OBTT suggests that rigorous multicenter pre‐clinical therapy screening may represent an important avenue to enhance the chance for successful translation. Finally, several potential paradigms for pre‐clinical therapy development based on the OBTT approach will be presented. Support: DAMD W81HWH‐14‐2‐0118/W81XWH‐10‐1‐0623.
Keywords: Consortium, Biomarker, Drug Screening, Translation
Lunch Wokshops
LW6 Intersection of TBI and Domestic Violence
INTERSECTION OF TRAUMATIC BRAIN INJURY AND DOMESTIC VIOLENCE
1University of Arizona, College of Medicine ‐ Phoenix, Phoenix, USA
2Phoenix Children's Hospital, Barrow Neurological Institute, Phoenix, USA
Domestic violence (DV) continues to be a pervasive problem that has been described as an ongoing social epidemic (Daire et al., 2014; Eastman et al., 2007), where one in three U.S. women has been raped, physically assaulted, and/or stalked by an intimate partner in her lifetime and one in 5 has experienced severe physical abuse (Black et al., 2011). Incomplete data indicate that abuse involves the head and face. Thus, the relationship between TBI and DV is increasingly evident and alarming. This session highlights the causes and consequences of TBI within the context of domestic violence, in stark contrast to athletic or military TBI. A multidisciplinary approach for TBI and DV education, assessment, and intervention is used as an example of what can be done to meet patients where they need services. As this situation has no preference for age, sex, gender, race, or socioeconomic status, additional talks highlight the direct and indirect impact of DV on the pediatric population, with particular focus on blood‐based biomarkers. Similarly, consideration is given to elder abuse and the societal approaches to intervene with policy and social change. Our members will understand the unique situations of DV and the impact on individual, family, and community function. Unquestionably, domestic violence intensifies the impact of TBI as a health care epidemic.
Keywords: domestic violence, concussion, community health, diagnosis
Breakout Sessions
S02 Measuring Functional Outcomes in Pre‐Clinical Blast Models
THE CUMULATIVE EFFECTS OF REPEATED LOW‐LEVEL BLAST EXPOSURE
Walter Reed Army Institute of Research, Blast‐Induced Neurotrauma, Silver Spring, USA
The emergence of evidence linking multiple mild traumatic brain injuries to progressive, long‐term debilitations and neurodegeneration has prompted concern over the cumulative deleterious effects of blast exposure on the brain and the need to mitigate this risk among Warfighters. Similar concerns have arisen over neurosensory impairments. At present, there are no set guidelines establishing cumulative limits for blast exposures in military personnel in combat or training operations. Using laboratory rats and an advanced blast simulator (ABS), which closely mimics free‐field blast, we have evaluated the cumulative effects of repeated daily low level blast exposures on auditory, visual, and neurological function and assessed changes in pathophysiological markers in the brain, which include the mechanosensitive cation channel receptor piezo2, ‐ TAR DNA binding protein‐43 (TDP‐43), the tight junction proteins claudin‐5 and occludin, and vascular endothelial growth factor (VEGF), relative to exposure flow conditions. Functional assessments with electroretinograms for vision and distortion product otoacoustic emissions and auditory brainstem response for the auditory system, revealed significant decrements that were accompanied by retinal damage and cochlear hair cell loss. Among the pathophysiological markers, changes in piezo2 were particularly noteworthy, and a significant positive correlation between peak blast overpressure and piezo2 levels (R = 0.624, p < 0.00001, n = 138) was observed. These responses were accompanied by changes in levels of the tightly‐regulated protein TDP‐43, which has been implicated in frontotemporal dementia and chronic traumatic encephalopathy, and could have negative consequences in the brain when the protein is abnormally expressed and aggregated. Changes in expression of VEGF and the tight junction protein claudin‐5, which each play an important role in maintaining blood‐brain barrier integrity, point to potentially heightened blood‐brain barrier vulnerability after repeated blast. Collectively, these findings illustrate vulnerability to low level repeated blast like that occurring in the training and operations of Soldiers as a first step towards identifying tolerable thresholds of blast exposure and developing an understanding of how to prevent these debilitations in soldiers exposed to blast.
Keywords: blast, repeated exposure, auditory, vision
S03 Therapeutic Strategies for CNS Regeneration and Functional Recovery
TARGETING NLRP3 INFLAMMASOME TO TREAT TRAUMATIC BRAIN INJURY WITH A NOVEL PHARMACOLOGICAL INHIBITOR
Virginia Commonwealth Univ., Anatomy and Neurobiology, Richmond, USA
Recent studies have identified that inflammasome complexes are responsible for inflammatory responses in many pathological conditions. Inflammasomes are intracellular multiprotein complexes that regulate the innate immune response, activation of caspase‐1, production of pro‐inflammatory cytokines IL‐1β and IL‐18, and induction of cell death (pyroptosis). Among inflammasome family members the nucleotide‐binding domain
Keywords: NLRP3 inflammasome, neuroinflammation, cortical impact injury, functional recovery
PATIENT‐REPORTED AND PERFORMANCE BASED OUTCOME AFTER TBI ‐ EUROPEAN EXPERIENCES FROM CENTER‐TBI
1University Medical Center, IMPS, Goettingen, Germany
2University of Florida, Psychiatry, Gainesville, USA
3University Pecs, Neuroscience, Pecs, Hungary
4Universityhospital Antwerp, Neurosurgery, Antwerp, Belgium
5University of Cambridge, Anaesthesia, Cambridge, UK
Most outcomes show significant, yet small improvement between 3 and 6 months with little change thereafter. Uni‐ and multivariate analyses of predictors (age, gender, GCS pre‐injury mental health status) especially indicate a strong negative effect of preinjury mental state on outcomes.
Keywords: TBI, Outcome, CenterTBI, HRQOL
S05 Spinal Interneurons After Spinal Cord Injury
TRANSPLANTATION OF V2A INTERNEURONS IN HYALURONIC ACID HYDROGELS AFTER SPINAL CORD INJURY
The University of Texas at Austin, Biomedical Engineering, Austin, USA
While lack of regeneration after SCI is often attributed to the formation of a glial scar, astrocytes have also been observed to be present where axons are able to enter or exit the lesion. This suggests that astrocytes are involved in both permissive and inhibitory environments post injury. V2a interneurons (INs) are glutamatergic, ipsilaterally projecting cells that have been found to be important for local rewiring following SCI, particularly in the phrenic circuit. In this work, we used a novel hyaluronic acid (HA)‐astrocyte extracellular matrix (ECM) hydrogel to deliver V2a interneurons into the injured spinal cord. Astrocytes were derived from mouse embryonic stem cells (mESCs) using retinoic acid followed by BMP‐4 and FGF‐1 to generate protoplasmic astrocytes. A detergent protocol was used to remove the cell leaving astrocyte ECM, which was lyophilized. V2a INs were derived from Chx10‐PAC CAG‐TdTomato mESCs as previously described. This cell line expresses puromycin resistance under control of the Chx10 promoter so, after selection, cultures contain 80% V2a INs. After differentiation, V2a INs were aggregated for 2 days. Astrocyte ECM was reconstituted in 1% HA‐methylfuran and crosslinked with PEG‐bismaleimide and V2a aggregates. The resulting gels were injected into Long‐Evans rats 2 weeks after a T8 dorsal hemisection SCI. Animals were immunosuppressed with cyclosporine‐A. Histological recovery was assessed 14 d after implantation. The phenotype of the transplanted V2as was assessed with Vglut2 and NeuN and transplanted cells were identified by TdTomato fluorescence. We found that HA hydrogels containing protoplasmic ECM support V2a IN survival after injury. Furthermore, we found that the presence of V2a INs with neuronal processes after 14 d. In addition to improving axon growth, protoplasmic ECM was found to reduce astrocyte reactivity around the lesion and to reduce infiltration of macrophages into the lesion and surrounding tissue compared to HA alone and sham implant. We found that transplanted V2a INs survived and extended processes into the host tissue. This work shows that astrocyte ECM maintains bioactivity and improves histological outcomes following SCI. In addition, these hydrogels can support cell transplantation.
Keywords: extracellular matrix, interneuron, hydrogel
TRANSCRIPTIONAL DYNAMICS OF NEUROREHABILITATION IN SPINAL CORD INJURY AT SINGLE‐NUCLEUS RESOLUTION
1Ecole Polytechnique Federale de Lausanne, Brain Mind Institute, Geneva, Switzerland
2National Institute of Neurological Disorders and Stroke, Spinal Circuits and Plasticity Unit, Bethesda, USA
Spinal cord injury (SCI) is a life‐changing event that has a devastating impact on quality of life. A major neurological consequence of SCI is partial or complete paralysis, which results from disruption of connections to the lumbar circuitry responsible for locomotion, often located below the level of injury. Targeted neuromodulation of the lumbar circuitry using epidural electrical stimulation not only enables walking in rodents and humans with severe SCI, but also triggers reorganization of this circuitry and restored partial control over previously paralyzed leg muscles without stimulation. However, the molecular and anatomical mechanisms underlying this remarkable neurological recovery remain largely unknown. We used single‐nucleus RNA‐sequencing (snRNA‐seq) to profile the gene expression of more than 100,000 cells of the lumbar spinal cord to dissect the transcriptional dynamics underlying the response to rehabilitation. By integrating data from several distinct neuromodulatory stimuli, our preliminary analysis uncovered candidate neuronal subtypes that may serve as key integration nodes responsible for driving plasticity and recovery of walking following neurorehabilitation. Future work will build on the identification of these candidate neuronal subtypes to experimentally probe the molecular and anatomical features of the circuits responsible for driving neurological recovery, with the ultimate goal of targeting the identified circuits in order to augment recovery in SCI patients.
Keywords: neurostimulation, spinal interneurons, single‐nucleus sequencing, locomotion, lumbar circuitry
SILENCING SPARED INTERNEURONS RESULTS IN BETTER STEPPING AFTER SCI IN THE RAT: CLINICAL IMPLICATIONS.
University of Louisville, Neurological Surgery, Louisville, USA
Within the cervical and lumbar spinal enlargements, central pattern generating (CPG) circuitry produces the rhythmic output necessary for limb coordination during locomotion. Long propriospinal neurons that inter‐connect these CPGs are thought to be critical for hindlimb‐forelimb coordination and are thus important components for functional recovery after injury and potential targets for therapies. Using a reversible virus‐based system, we found that silencing long ascending propriospinal neurons (LAPNs) that connect the lumbar (L1‐3) segments to cervical (C5‐7) segments disrupts left‐right alternation of both the hindlimbs and the forelimbs in otherwise uninjured adult female SD rats. These perturbations to interlimb coordination were independent of the locomotor rhythm, did not affect intralimb coordination, and did not disrupt the speed‐dependent (or any other) principal features of locomotion. We then gave these animals a moderate contusive injury at T10 and let them recover for 6 weeks. Finally, we silenced the LAPNs again, effectively reducing the number of spared ascending axons that cross the injury. Exactly opposite to our expectations, we observed significantly improved stepping (gait and kinematics) in injured animals with silenced LAPNs which was reversed when silencing ceased. The most likely explanation for these observations is that the injury results in incomplete or garbled information being exchanged by the two enlargements via long propriospinal interneurons. We propose that silencing the LAPNs reduced the exchange of incomplete information and allowed the lumbar circuitry to function more autonomously. These observations suggest that some axons that are spared after an incomplete contusive injury are actually detrimental, either directly or indirectly, to function. Further, these findings have significant clinical implications in scenarios where epidural stimulation or other forms of neuromodulation are used to drive circuitry below the level of injury.
Supported by the Kentucky Spinal Cord and Head Injury Research Trust 13‐14 and the NIH GM103507, R01 NS089324.
Keywords: locomotor, central pattern generator, propriospinal neuron, interneuron, synaptic silencing
S08 Use of Alternative Neurotrauma Models in Defining and Assessing Functional Outcome Measures
GENETIC VARIANTS AFFECT THE RISK OF TRAUMATIC BRAIN INJURY OUTCOMES
University of Wisconsin‐Madison, Department of Medical Genetics, Madison, USA
Using a Drosophila melanogaster (fruit fly) model of closed head traumatic brain injury (TBI), we have found that naturally occurring variation in genetic background substantially influences the severity of secondary injury responses following TBI. Single nucleotide polymorphisms identified through our genome‐wide association study (GWAS) analyses implicate genes involved in tissue barrier function, energy homeostasis, and microtubule function in the differential secondary injury response. Furthermore, our genetic and pharmacological interventions that alter these genes and cellular processes support their importance in generating heterogeneity in TBI outcomes.
Keywords: Drosophila, Microtubules, GWAS, Innate immunity
S13 Under Construction: The Function of the Teenage Brain After TBI
ADOLESCENT TBI AND ADDICTIVE BEHAVIOUR: A SILENT EPIDEMIC IN DIRE NEED OF IMMEDIATE PREVENTION EFFORTS
Dalhousie University, Department of Community Health and Epidemiology, Halifax, Canada
Here we review studies conducted by our group looking at the association between TBI and substance use, and their mental health and behavioural adverse health correlates from 2013 to present. In particular, we describe the combined impact of traumatic brain injury (TBI) and hazardous drinking on mental health and behavioral issues among Ontario adolescents. This latest study assessed the incremental co‐occurrence of hazardous drinking with history of TBI, in comparison to experiencing just one of these conditions. The study assessed a cross‐sectional subsample of 3130 Ontario adolescents attending grades 9 through 12, ages 10 through 21 were surveyed in 2013 as part of the Centre for Addiction and Mental Health's Ontario Student Drug Use and Health Survey. Recent(past year) and former (lifetime, excluding last year) TBI were defined as trauma to the head that resulted in loss of consciousness for at least five minutes or overnight hospitalization. Current hazardous drinking was derived using the Alcohol Use Disorders Identification Test (AUDIT). Results showed that an estimated 11.8% (95% CI: 10.1, 13.8) reported a history of formerTBI and were not hazardous drinkers; 4.0% (95% CI: 2.9, 5.5) reported recentTBI and were not hazardous drinkers; 13.7% (95% CI: 12.3, 15.3) were hazardous drinkers who never had a TBI; 4.1% (95% CI: 2.9, 5.8) had former TBI with co‐occurring hazardous drinking; and 2.2% (95% CI: 1.6, 3.0) had recentTBI with co‐occurring hazardous drinking. Most odds increased significantly and were between 2 to 3 times higher for reporting compromised mental health, violent and non‐violent conduct behaviors, and reported victimization for classifying as hazardous drinker at the time of testing with co‐occurring either formeror recent TBI compared to classifying as not having either of these conditions. Adolescents classified as hazardous drinkers with formerTBI had numerous and higher odd ratios for conduct behaviors than hazardous drinkers with recentTBI. Results point to a silent TBI epidemic and a strong interplay between TBI and hazardous drinking, which is associated with harmful associations on their academic performance, short term but also long term in terms of vocational success and overall quality of life.
Keywords: adolescent TBI, Substance use, mental health, conduct behaviours, population based
DO RATHLETES RECOVER FROM CONCUSSION FASTER THAN SEDENTARY RATS?
University of California Los Angeles, Neurosurgery, Los Angeles, USA
Adolescents and young adults show the highest incidence of mild traumatic brain injury (mTBI), with sports related activities as the majority contributor. Roughly 1/3 of these are estimated to have received a repeat mTBI (rTBI). This study addresses the physical activity state as a dependent variable prior to rTBI in adolescent rats. It is hypothesized that the post‐concussion recovery profile is dependent on the prior states of activity level. Sedentary animals were given access to locked running wheels for 10d prior to and after sham injury. Rathletes were allowed to run 10d prior to rTBI or sham injury. Rathletes with rTBI were run at 3 different times post injury: no run (n = 7), immediate run (n = 8), or 3‐day delay (n = 7). Animals were tested on motor and cognitive tests using a rat sports concussion assessment tool (rat SCAT) on post‐injury days 1,3,5,7, and 10. Anxiety: A repeated measures analysis of variance found sedentary shams showed lowest anxiety like behaviors (high anxiolytic factor, 107.2) following injury compared to all other groups on all testing days (41.69‐66.3, p's < 0.05). Injured rathletes showed anxiety levels closer to injured shams (41.69‐66.3 vs 50.05, not significant). Social: We found that rTBI +3d delay group exhibited 2x more playful behavior with intruder rats compared to shams (47% vs 20%, p < 0.05), while the rTBI+immed showed the least number of social contacts (18.5 vs. 25.9, p < 0.01). Motor: Sham+immed showed fewer foot slips on day 1 (20.7%) compared to sham+no run (41.5%, p < 0.05). While others have shown deficits in motor behavior following rTBI, our injured rathletes performed at the level of sham rathletes. No significant differences were seen for memory tasks or allodynia. As all rTBI subjects were given access to an open running wheel, these data suggest that athletes may be protected from motor impairment. Further, this study is the first to address the return‐to‐play activity in adolescents. Results suggest delayed return‐to‐activity improved social behavior following rTBI. UCLA BIRC & BrainSPORT, Easton Labs, NIH NS110757.
Keywords: adolescents, return‐to‐play, repeat TBI, athletes
S19 Latest Advances in Functional Imaging After TBI
RESILIENCE OF SUBCORTICAL AROUSAL NUCLEI IN PATIENTS RECOVERING FROM TRAUMATIC COMA
Marta Bianciardi1, Saef Izzy2, Bruce Rosen1, Larry Wald1,
1Massachusetts General Hospital, Radiology, Boston, USA
2Brigham and Women's Hospital, Neurology, Boston, USA
3Massachusetts General Hospital, Neurology, Boston, USA
Lesions that injure subcortical ascending arousal network (AAN) nuclei are implicated in the pathogenesis of coma in patients with severe traumatic brain injury (TBI). However, due to difficulty in localizing AAN nuclei with conventional MRI, it is unknown which lesioned nuclei are involved in coma, and which are compatible with recovery of consciousness. We mapped our recently developed atlases for brainstem AAN nuclei, as well as current thalamic, hypothalamic, and basal forebrain atlases, to 3 Tesla susceptibility‐weighted images (SWI) in 12 patients with acute severe TBI who presented in coma and who recovered consciousness within six months. Next, we measured the volume of SWI microbleeds within each AAN nucleus. Our findings indicated that there was no single nucleus whose injury was implicated in coma pathogenesis. Rather, we identified multiple combinations of partially injured brainstem nuclei (e.g. pedunculotegmental nucleus, midbrain reticular formation, ventral tegmental area, and substantia nigra subregions) and thalamic nuclei that were involved in coma and were compatible with recovery of consciousness. The volume of SWI microbleeds within these nuclei correlated with the number of days until command‐following (p ≤ 0.05). In conclusion, our study suggests that AAN nuclei are resilient in patients recovering from traumatic coma. Although the mechanisms underlying AAN resilience remain to be elucidated, these observations suggest that redundant circuitry may facilitate functional reorganization of the network after structural injury to network nodes. SWI evaluation of AAN nucleus lesions using novel brainstem atlases may help elucidate the mechanisms by which patients with traumatic coma recover consciousness.
Keywords: brainstem, coma, consciousness, networks
S20 Sex Differences in TBI Pathophysiology
SEXUAL DIMORPHISM IN THE INFLAMMATORY RESPONSE TO TRAUMATIC BRAIN INJURY
Houston Methodist Research Institute, Department of Neurosurgery, Center for Neuroregeneration, Houston, USA
The activation of resident microglial cells, alongside the infiltration of peripheral macrophages, are key neuroinflammatory responses to traumatic brain injury (TBI) that are directly associated with neuronal death. Sexual disparities in response to TBI have been previously reported; however, it is unclear whether a sex difference exists in neuroinflammatory progression after TBI. We exposed male and female mice to moderate‐to‐severe controlled cortical impact (CCI) injury and studied glial cell activation in the acute and chronic stages of TBI using immunofluorescence and in situ hybridization analysis. We found that the sex response was completely divergent up to 7 days postinjury. TBI caused a rapid and pronounced cortical microglia/macrophage activation in male mice with a prominent activated phenotype that produced both pro‐ (IL‐1β and TNFα) and anti‐inflammatory (Arg1 and TGFβ) cytokines with a single‐phase, sustained peak from 1 to 7 days. In contrast, TBI caused a less robust microglia/macrophage phenotype in females with biphasic pro‐inflammatory response peaks at 4 hours and 7 days, and a delayed anti‐inflammatory mRNA peak at 30 days. We further report that female mice were protected against acute cell loss after CCI, with male mice demonstrating enhanced astrogliosis, neuronal death, neutrophil infiltration, and increased lesion volume through 7 days post‐injury. This local inflammation does not exclusively affect the brain, and it also induces a systemic acute phase response that affects other organs. Our results show that the liver produces serum amyloid A (SAA) as acute phase protein at high levels in the initial hours after CCI injury in mice. SAA levels are higher in males compared to female mice. Collectively, these findings indicate that TBI leads to a more aggressive central and peripheral inflammatory profile in male compared with female mice during the acute and subacute phases postinjury. Understanding how sex affects the course of inflammation following brain injury is a vital step toward developing personalized and effective treatments for TBI.
Keywords: Neuroinflammation, Neurorestoration, Microbiome, Brain‐periphery Axis, Neuroprotection, traumatic brain injury