Probing Estrogen Sulfotransferase-Mediated Inflammation with [ 11 C]-PiB in the Living Human Brain

Abstract

Background:

2-(4’- [¹¹C]Methylaminophenyl)-6-hydroxybenzothiazole ([¹¹C]-PiB), purportedly a specific imaging agent for cerebral amyloid-β plaques, is a specific, high affinity substrate for estrogen sulfotransferase (SULT1E1), an enzyme that regulates estrogen homeostasis.

Objective:

In this work, we use positron emission tomography (PET) imaging with [¹¹C]-PiB to assess the functional activity of SULT1E1 in the brain of moyamoya disease patients.

Methods:

Ten moyamoya subjects and five control patients were evaluated with [¹¹C]-PiB PET and structural MRI scans. Additionally, a patient with relapsing-remitting multiple sclerosis (RRMS) received [¹¹C]-PiB PET scans before and after steroidal and immunomodulatory therapy. Parametric PET images were established to assess SULT1E1 distribution in the inflamed brain tissue.

Results:

Increased [¹¹C]-PiB SRTM DVR in the thalamus, pons, corona radiata, and internal capsule of moyamoya cohort subjects was observed in comparison with controls (p ≤ 0.01). This was observed in patients without treatment, with collateralization, and also after radiation. The post-treatment [¹¹C]-PiB PET scan in one RRMS patient also revealed substantially reduced subcortical brain inflammation. In validation studies, [¹¹C]-PiB autoradiography signal in the peri-infarct area of the rat middle cerebral arterial occlusion stroke model was shown to correlate with SULT1E1 immunohistochemistry.

Conclusion:

Strong [¹¹C]-PiB PET signal associated with intracranial inflammation in the moyamoya syndrome cohort and a single RRMS patient appears consistent with functional imaging of SULT1E1 activity in the human brain. This preliminary work offers substantial and direct evidence that significant [¹¹C]-PiB PET focal signals can be obtained from the living human brain with intracranial inflammation, signals not attributable to amyloid-β plaques.

Keywords

Inflammation moyamoya PET PIB sulfotransferase

INTRODUCTION

Earlier work has reported the use of 2-(4^′- [¹¹C]methylaminophenyl)-6-hydroxybenzothiazole (“Pittsburgh Compound B” or “ [¹¹C]-PiB”) to visualize amyloid-β (Aβ) plaque distribution in the brain of Alzheimer’s disease (AD) patients [1]. However, [¹¹C]-PiB specificity for Aβ plaques has been questioned when possible in vivo signals emerging from other tissue targets met recognition. Regardless, the possibility of detecting [¹¹C]-PiB PET signals not attributable to Aβ plaque distribution in the living human brain has remained unproven [2 –4].

In this work, the in vivo behavior of [¹¹C]-PiB in inflammatory disease conditions of the human brain that do not implicate Aβ aggregates was evaluated. For this purpose, we studied patients with moyamoya syndrome, a progressive cerebrovascular disorder caused by arterial stenosis in the Circle of Willis [5]. Stenotic changes give rise to small collateral blood vessels, or “moyamoya vessels,” that form to compensate for the lack of blood supply. On an arteriogram, moyamoya vessels branching from the basal ganglia resemble a “puff of smoke”—a literal translation from Japanese (もやもや).

Inflammation is evident in virtually all associated risk factors for this condition, including the presence of cytokines, prostaglandins, and matrix metalloproteinases [6, 7]. Therefore, moyamoya syndrome is an inflammatory disease, a heterogenous condition resulting from various disparate origins that coalesce around a similar set of symptoms as the condition progresses [8].

Estrogen has been implicated in the concentration dependent regulation of inflammation [9]. At a high affinity (K_D = 1 nM), estrogen has direct interactions with estrogen receptors on immune cells that can inhibit polymorphonuclear leukocyte migration to the site of insult and suppress cytokine production in response to vascular injury [10, 11]. Estrogen can establish the hematopoietic niche for regulatory cells (T_reg), such as CD25⁺ cells, and suppressing effector T_H17 cells, which can facilitate pro-inflammatory cytokines and autoimmune responses [12 –14].

Estrogen sulfotransferase (SULT1E1) (EC2.8.2.4) is one of several regulatory enzymes of estrogen homeostasis, but the only one catalyzing sulfoconjugation at a concentration that competes with estrogen receptors (K_M = 5 nM) [15, 16]. Estrogen sulfation can establish a reservoir of the hormone that can be activated whenever necessary by the steroid sulfatase enzyme, which catalyzes the hydrolytic reaction [17 –20].

Thus, [¹¹C]-PiB, a high-affinity substrate for SULT1E1, was considered a good candidate for assessing intracranial inflammation in the human using PET [19]. The enzyme specifically sulfates [¹¹C]-PiB to produce its 6-O-sulfate, whose in vivo tissue accumulation may resemble the cellular trapping mechanism of 2-deoxy-2- [¹⁸F]fluoro-D-glucose (2-FDG) [19]. Consequently, this work assesses the hypothesis that regional [¹¹C]-PiB brain retention correlates with the distribution of functional SULT1E1 and, ultimately, the inflammatory response [20]. In this work we propose that through this mechanism, when properly interpreted, [¹¹C]-PiB PET imaging may be a powerful tool to investigate disease progression in moyamoya syndrome and other brain inflammatory conditions.

MATERIALS AND METHODS

Patient cohorts

This study met compliance with the UCLA Institutional Review Board and the Medical Radiation Safety Committee guidelines. Prior to scanning, our group obtained informed consent from patients featured in this study. Patients with confirmed moyamoya syndrome (10 subjects; with a wide range of ages: 27.0 to 76.9 years of age; mean age: 47.3±16.5 years) were compared with control subjects (5 subjects; mean age: 30.9±3.2 years) that exhibited no symptoms or risk factors for moyamoya syndrome (Table 1). Control subjects were from a cohort of persons at-risk for autosomal dominant Alzheimer disease (ADAD) enrolled in the Dominantly Inherited Alzheimer’s Network (DIAN) who were tested and found not to have inherited an ADAD mutation. Selection of these controls from the DIAN study was made because they are within the early age range of Moyamoya 1 through Moyamoya 5 (27.0 to 38.4 years), which is not a range most commonly described in the [¹¹C]-PiB literature. In terms of [¹¹C]-PiB brain signal distribution, older age controls most commonly found in the literature do not differ much from that of younger controls, and they were not included in this work.

Table 1

Moyamoya Syndrome Cohort Demographics^*. The moyamoya cohort reveals diverse symptoms, yet no patient had signs of dementia at the time of imaging. The mean age was 47.3±16.5 years. Bilateral encephalo-duro-arteriosynangiosis (EDAS) is an indirect revascularization procedure to stimulate vessel formation by using a segment of the temporal artery on the brain surface without an anastomosis. STA-MCA bypass, though, forms a junction between the superior temporal artery and the middle cerebral artery to improve perfusion. One patient had a ventriculoperitoneal shunt for hydrocephalus. The control cohort comprises of 5 patients (3 females and 2 males) with an average age of 30.9±3.2 years

Patient ID	Age	Gender	Symptoms	Clinical Presentation	Surgical Treatment
Moyamoya 1	27.0	Female	Dysphagia, dysarthria, right motor deficits	Radiation-induced vasculopathy with a prior history of astrocytoma, Occlusion of right and left ICA, M1, and right intracranial vertebral artery	Ventriculoperitoneal Shunt
Moyamoya 2	30.2	Female	Headaches, insomnia, diminished cognition	Bilateral moyamoya syndrome with ICA, ACA and MCA occlusion	Bilateral EDAS
Moyamoya 3	33.4	Female	Numbness, diffuse bilateral headaches	Cushing disorder	Bilateral EDAS
Moyamoya 4	38.0	Female	Headaches, carpal tunnel syndrome	Moyamoya syndrome, type I Diabetes	–
Moyamoya 5	38.4	Male	Lightheadedness, left arm tingling, clumsiness	Moyamoya syndrome, bifrontal Hypoperfusion (R > L)	Bilateral EDAS
Moyamoya 6	51.0	Male	Persistent dull bifrontal headaches	Moyamoya syndrome	–
Moyamoya 7	51.2	Male	Improved palpitations	Possible moyamoya disease, prior subdural hemorrhage concurrent with non-ST elevation myocardial infarct, hypertension, ventricular bigeminy	–
Moyamoya 8	55.7	Male	Dysarthria	Multiple intracranial stenoses, post-operative stroke after STA-MCA bypass	STA-MCA bypass.
Moyamoya 9	66.4	Female	Mild yet persistent problems with memory	Intraventricular hemorrhage with history of moyamoya syndrome	–
Moyamoya 10	76.9	Female	Vertigo, hallucinations, bilateral numbness, trigeminal neuralgia	Prior right occipital stroke, atherosclerotic disease with history of moyamoya syndrome	–

^*Time elapsed for Moyamoya 2–10 is approximately 6 months to 2 years between the [¹¹C]-PiB scan and diagnosis. Moyamoya 1 has had moyamoya syndrome since childhood.

In addition, one male 50.3-year-old patient with RRMS was under standard of care. His routine treatment included interferon-β (Avonex^®) followed by additional prednisone therapy to treat symptomatic central nervous system inflammation.

Imaging

Fully detailed imaging protocols for PET and MRI can be found in the Supplementary Material. With cerebellar grey matter as reference tissue, the Simplified Reference Tissue Model established parametric PET images of [¹¹C]-PiB uptake from distribution volume ratio (SRTM DVR). The procedure for image analysis was previously referenced [21].

Control subjects and the RRMS multiple sclerosis patient received structural T1 MRI scans. The entire moyamoya cohort received FLAIR, T2, and diffusion-weighted MRI scans to visualize flow voids, restricted diffusion and hyperintensities.

Middle cerebral arterial occlusion (MCAO) stroke model

All animal experiments met compliance with the UCLA Animal Care and Use Committee guidelines. The procedure for the MCAO model is referenced in the Supplementary Material section. Briefly, the MCAO model entailed 1 h of occlusion followed by [¹¹C]-PiB PET imaging that occurred after 48 h of reperfusion. Immunohistochemical staining for SULT1E1 and 2,3,5-triphenyltetrazolium chloride staining of the ischemic core was subsequent to euthanasia after imaging and sectioning.

Statistical analysis

Full details of all statistical analysis with R-Studio version 0.99.486 is featured in the Supplementary Material. Briefly, nonparametric analysis assessed differences between cohorts, while applying multiple comparisons corrections.

RESULTS

[¹¹C]-PiB SRTM DVR in moyamoya syndrome

Subcortical and midbrain regions with substantially elevated [¹¹C]-PiB SRTM DVR highlight inflammation in moyamoya subjects. Diminished perfusion from moyamoya vessels facilitate microstructural damage in subcortical regions that elicits persistent inflammatory responses. Demyelination and axonal loss within the corona radiata and thalamus of moyamoya patients seen on differential kurtosis and tensor MRI confirm microstructural damage induced by chronic hypoperfusion [22]. Additionally, autopsies on moyamoya patients highlight that intracranial hemorrhage in the pons, basal ganglia, and thalamus is common, and phosphorylated tau accumulation in the brain stem in one reported case [23, 24]. Statistically significant differences between [¹¹C]-PiB uptake between the moyamoya cohort subjects (i.e., without treatment, with collateralization, and also after radiation) and the control within the corona radiata, internal capsule, pons, and thalamus, support the conclusion for robust and ongoing inflammation in these regions (Fig. 1).

Fig.1

Regions of Prominent [¹¹C]-PiB Uptake in Moyamoya Patients. Regional subcortical and midbrain brain [¹¹C]-PiB SRTM DVR values in the moyamoya cohort demonstrate significantly higher uptake than in the corresponding regions of the control cohort. Control cohort signals did not deviate from previously determined regional [¹¹C]-PiB uptake in non-demented controls [45].

The corresponding table accompanying Fig. 1 summarizes the statistical comparisons, as follows:

Despite a larger age range in the moyamoya cohort when compared to control patients, the relationship between age and [¹¹C]-PiB signal differences, as dictated by the Friedman test between the two cohorts, lacks significance (p > 0.15).

Despite the rather heterogeneous composition of the moyamoya syndrome cohort, significant differences between controls and moyamoya cases were found in SRTM DVR values of the following regions: corona radiata, thalamus, internal capsule, and pons (**p ≤ 0.005; *p ≤ 0.01). Post-hoc testing results with the Dunn test validated significance in these regions (p < 0.05). Moyamoya 2, 3, and 5 each underwent bilateral encephalo-duro-arterio-synangiosis (EDAS) surgery to reestablish blood flow. SRTM DVR within the thalamus and internal capsule of the EDAS group produces statistical significance (0.01 < p≤0.05) in comparison to the controls (Supplementary Figure 1). There were no correlations between the SRTM DVR values of significant subcortical regions (Fig. 1) and their corresponding SRTM R1 value to validate the absence of a relationship between flow and [¹¹C]-PiB brain retention (Supplementary Table 1).

Ischemic condition and relative [¹¹C]-PiB signal in the brain of moyamoya patients

In the case of the untreated moyamoya patient (Fig. 2A), the [¹¹C]-PiB PET signal is milder than the other examples featured, but the subcortical tissues sustain an elevated profile in support of the moyamoya syndrome clinical diagnosis. White matter in the corona radiata, the internal capsule, and thalamus are elevated, which are consistent with subcortical inflammation associated with hypoperfused tissue in moyamoya.

Fig.2

Chronic Inflammatory Signal from [¹¹C]-PiB Moyamoya Syndrome. The figure displays the heterogeneous [¹¹C]-PiB PET response in the various moyamoya cohort subjects presented in this work: A) with no surgical intervention of any kind (Moyamoya 4, 38-year-old female); B) after receiving an EDAS procedure for cerebral revascularization demonstrating a sustained subcortical [¹¹C]-PiB uptake (Moyamoya 3, 33.4-year-old female); C) a patient with moyamoya syndrome with a ventriculoperitoneal (VP) shunt and severe trauma from sequelae of radiation treatment for childhood astrocytoma, as featured in the T2 and ADC MRIs (Moyamoya 1, 27-year-old female); D) a control subject with a normal T1 MRI and a [¹¹C]-PiB PET normal profile that has been characteristically reported in the literature by multiple authors (DIAN control 012249, 22.3-year-old female).

Co-registered [¹¹C]-PiB PET scans in surgically treated patients (Fig. 2B,C) demonstrate profound subcortical and midbrain retention in the moyamoya patient that is lacking in the corresponding uptake of the control patient. Moyamoya 1 subject (Fig. 2C) presented with astrocytoma as a child and suffered from radiation-induced vasculopathy that caused systemic occlusion and chronic stenosis. This patient received a ventriculoperitoneal shunt to relieve pressure and increase cerebral perfusion (Table 1). Sustained cortical damage demonstrates elevated diffusion, whereas suppressed apparent diffusion coefficient values corroborating restricted diffusion indicate ischemia in the basal ganglia and periventricular tissue. MRI apparent diffusion coefficient values, which exhibit ischemic signs, coexist with elevated thalamic and pontine [¹¹C]-PiB signal accumulation, with subcortical structures exhibiting a substantial gradient of [¹¹C]-PiB PET signal increases medially toward the midbrain. Preponderant increase of [¹¹C]-PiB PET contrasts against the featured age-matched control patient (23.4%, 28.8%, 21.5%, 50.4%, and 38.4%, respectively) (Fig. 2C). Unlike other patients, however, [¹¹C]-PiB PET signal extends beyond subcortical and midbrain tissue to the frontal lobe, to reflect the global radiation-induced chronic inflammation.

The [¹¹C]-PiB PET response in moyamoya syndrome subjects is in absence of amyloid aggregate accumulation, which it is consistent with the SULT1E1-mediated brain retention of [¹¹C]-PiB in the rat MCAO Model (Fig. 3A). The [¹¹C]-PiB signal is peripheral to the site of injury and is consistent with the post-insult distribution of SULT1E1 in that tissue.

Fig.3

[¹¹C]-PiB Uptake and SULT1E1 Expression in MCAO Rat Model. [¹¹C]-PiB autoradiography of a non-hemorrhagic stroke model after 48 h of reperfusion. A) Green and blue boundaries represent the ischemic core, with peri-infarct regions in red. [¹¹C]-PiB retention is diminished in the ischemic core (–29%) and increased in the peri-infarct regions (+39%), in both cases when compared to the contralateral side. IHC staining for SULT1E1 expression is more robust and abundant in the peri-infarct (B) versus nominal expression for the contralateral side (C). The brain slice is provided as anatomical reference (D) [Credit for the atlas: Paxinos G and Watson C, The Rat Brain in Stereotaxic Coordinates, 6th ed. Elsevier (2007)].

The dynamic PET signal in a multiple sclerosis patient further confirms that the brain [¹¹C]-PiB PET signal may be present in absence of Aβ deposition, and brain PET signal is susceptible to anti-inflammatory therapy (Fig. 4). The patient exhibited robust uptake in white matter prior to prednisone treatment. After prednisone administration that complied with his standard of care treatment, the previous robust signal dropped by 34.3% in the right ventral pallidum, 30.0% in the corona radiata, 14.7% in the thalamus, 16.7% in the internal capsule, and 8.27% in the pons.

Fig.4

Dynamic SULT1E1 Response in White Matter of Multiple Sclerosis. A 50.3-year-old male patient with RRMS has a T1 MRI scan with absent damage visible in white matter (A). Co-registered [¹¹C]-PiB PET scans before and one month after steroidal therapy demonstrate an ostensible reduction in [¹¹C]-PiB signal within the subcortical white matter, pallidum, and pons (B and C, respectively).

DISCUSSION

This is the first report using [¹¹C]-PiB PET imaging to visualize intracranial human brain inflammation, in this case with moyamoya patients. These results in living subjects with moyamoya syndrome are consistent with the hypothesis that elevated SULT1E1 expression and functional activity in brain tissue of the assessed patients is observable.

Previous reports have discussed the complex role of estrogen in brain diseases while conferring anti-inflammatory and neuroprotective effects. Estrogen downregulates microglial activation, promotes angiogenesis, and prevents peripheral immune cell invasion into the site of injury during the acute phase of ischemic stroke [9]. The presence of aromatase, which converts testosterone and other C19 steroids to estradiol in the human brain, supports these observations further through regulation of brain plasticity, changes in synaptic function, and neuroprotective effects [25].

Estrogen inactivation by human sulfotransferases (hSULTs) enables dynamic cytokine proliferation contributing to the etiology and pathogenesis of inflammation in the onset of disease. Three hSULTs can metabolize estrogens: SULT1A1 (EC2.8.2.1), SULT1E1 (EC2.8.2.4), and SULT2A1 (EC2.8.2.2) [26]. To date however, neither mRNA nor protein expression of SULT2A1 has yet been reported in the human brain [26]. SULT1A1 is mainly a xenobiotic enzyme, known to catalyze the sulfation of small phenols, but inhibition at high 17-β-estradiol concentrations has been demonstrated (e.g., 17β-estradiol has been shown to be a SULT1A1/2 substrate in human liver, breast cancer cells, and fetal lung extracts with a K_m of 2–5 microM) [27, 28].

Among all hSULTs, only SULT1E1 possesses sufficient affinity for sulfoconjugation of 17β-estradiol (E2) [K_m ∼5 nM] to allow its inactivation at a concentration range that competes with binding to estrogen receptors (ER) [K_D: 1 nM] [6]. SULT1E1 expression has been documented in rodents, it has not been reliably reported in the normal human brain [13 , 29], but it has been associated to stroke in humans [30]. Beyond these three hSULTs with the ability to metabolize estrogens, the mRNA expression of human hydroxysteroid sulfotransferase SULT2B1b has been reported in the brain. SULT2B1 isoforms shows that these enzymes are selective for the sulfation of 3β-hydroxysteroids but have no activity toward testosterone or 17-β-estradiol has been detected [26]. Since [¹¹C]-PiB is a good substrate for SULT1E1 (Km = 1.42 μM; Vmax 1.99 nmol/min/mg and Vmax/Km of 1.40 nmol/min/mg/μM) and a poor substrate for SULT1A1 [19], the combined available evidence suggests that the [¹¹C]-PiB PET signal is consistent with the participation of SULT1E1 in the disease-mediating inflammatory responses through estrogen-dependent multifarious signaling cascades.

The MCAO rat model of unilateral ischemic stroke provides additional biological evidence in support of the participation of functional SULT1E1 in [¹¹C]-PiB uptake in surrounding tissue soon after post-infarct reperfusion. Increased [¹¹C]-PiB uptake in the peri-infarct area with corresponding SULT1E1 expression is validated by immunohistochemical staining. Prior confirmation of reactive astrocytes, which release abundant cytokines and prostaglandins during brain injury, ipsilateral to the ischemic core in the peri-infarct area and the formation of the glial scar ensues from MCAO [31 –33]. These results also elucidate an active SULT1E1 enzyme expression in areas that serve to ensure a robust inflammatory response, with localized estrogen metabolism.

It is not openly recognized, but [¹¹C]-PiB retention as a result of brain inflammation has also literature precedence. The work of Ly and coworkers with 21 ischemic stroke patients provided substantial evidence of the occurrence of consistently ‘higher [¹¹C]-PiB retention within the ipsilateral peri-infarct region compared to the contralateral side’, particularly in the white matter around the infarct region [34]. In the apparent absence of amyloid brain deposition, the authors labeled the focal [¹¹C]-PiB retention as uncertain with a requirement for further investigation. However, the MCAO rat models described in the same study also lend support to the hypothesis of an acute inflammatory response produced by focal ischemic stress as responsible of the focal [¹¹C]-PiB retention.

Our work also demonstrates that the [¹¹C]-PiB PET response to brain inflammation is not exclusive to the moyamoya syndrome. Inflammation is also observable in a RRMS subject and, for the first time, an acutely dramatic effect upon [¹¹C]-PiB PET signal in a human subject resulting from treatment. Previous work on [¹¹C]-PiB PET imaging in multiple sclerosis in humans and baboons suggested that, in absence of amyloid deposition, myelin binding protein was the likely target for the tracer [35]. The present results do not seem in agreement with this conclusion based on the reported mechanism of demyelination-mediated axonal damage [36]. The multiple sclerosis patient (Fig. 4B) showed substantial white matter [¹¹C]-PiB retention, yet cortical grey matter is virtually devoid of tracer retention. Most remarkable, this patient’s prednisone regimen for downregulating inflammation and controlling symptoms produced significant reductions in the [¹¹C]-PiB PET signal of white matter on the scan signal following treatment (Fig. 4C). The figure illustrates a reduction in signal after prednisone routine clinical treatment in the RRMS patient, which would have been unexpected if myelin binding protein were truly the target for [¹¹C]-PiB. Diminished [¹¹C]-PiB PET signal after combined treatment with interferon-β and methylprednisolone is consistent with suppressed inflammation and reduction in SULT1E1 expression.

The reported findings in this work, inconsistent with the attribution of [¹¹C]-PiB brain accumulation to amyloid (Aβ) tissue targets, also find precedence in the [¹¹C]-PiB accumulation in meningiomas, tumors driven by inflammatory tumorigenesis, in living human subjects [2, 37]. Since the presence of the 6-hydroxy aromatic substitution in [¹¹C]-PiB permits its sulfotransferase-mediated sulfation, it may be further inferred that other structurally related 6-hydroxy substituted benzothiazole/benzoxazoles in use as amyloid imaging agents may have in vivo behavior similar to [¹¹C]-PiB, as shown in some publications [38]. These would include radiofluorinated 6-hydroxy derivatives such as [¹⁸F]flutemetamol, [¹⁸F]AZD4694, and [¹¹C]AZD2184, whose brain signal has been attributed to binding of brain Aβ aggregates and not to the action of estrogen sulfotransferase.

Interestingly, carbon-11 labeled 2-(4^′-methylaminophenyl) benzothiazole (BTA-1), a thioflavin analog of PiB lacking the 6-hydroxy group, has very poor in vivo binding in the AD living human brain, even though they share similar nanomolar in vitro binding affinities to amyloid aggregates. This observation provides additional strong indication that the 6-hydroxy substitution contributes to [¹¹C]-PiB retention in the human brain [2, 39].

This work has limitations in the number of human subjects involved, and further work would be needed to confirm these initial results with [¹¹C]-PiB-PET in brain inflammation syndromes. Testing with additional animal models of both ischemic stroke and moyamoya would be useful to reproduce these results and characterize relationships between SULT1E1 and inflammatory markers further. In humans, the challenge is the difficulty of patient recruitment due to the low incidence of moyamoya in the United States, which is significantly lower than in Asian countries [40]. Moreover, the variability in the stages of pathogenesis in moyamoya disease subjects at the time of recruitment, interferes with standardizing cohorts for PET imaging. Other factors may be less significant, as both Friedman testing and analysis of covariance (ANCOVA) failed to establish significant interactions between diagnosis and age or gender. Additionally, to collect further evidence on the sensitivity of [¹¹C]-PiB to visualize intracranial inflammation, PET scans of RRMS patients with immunomodulatory and steroidal therapies can be very helpful to reproduce the initial findings in this report.

Conclusions

Notably, Aβ protein aggregates are unobserved in the brains of moyamoya patients at autopsy [41, 42]. The aforementioned results demonstrate that [¹¹C]-PiB elevated signal in the brains of these patients is not due to any heretofore undiscovered Aβ aggregate deposition. Instead, these cases are consistent with chronic and dynamic inflammation in the brain with homeostatic estrogen synthesis. These results also strongly caution that attribution of [¹¹C]-PiB PET signals to the presence of Aβ aggregates in the brain of AD patients or asymptomatic controls should be carefully re-examined, considering the high inflammatory component in the inception of AD. This uncertain representation of Aβ neuropathology by [¹¹C]-PiB and other amyloid PET agents has resulted in attribution of significant Aβ plaques deposition in the brains of approximately 30% of cognitively normal control subjects [43]. These positive imaging results have been suggested as indicative of Aβ-mediated higher AD risk. Even though sparse amyloid deposition has been demonstrated in normal control human subjects, in a rather recent large clinical-pathological review of data from multiple laboratories, it is concluded that “it is extraordinarily rare for a case with widespread, dense AD-type neocortical lesions to lack documented antemortem cognitive decline” [44]. Re-evaluation of these amyloid imaging results in normal subjects, and attribution of positive [¹¹C]-PiB PET images to inflammation, may provide valuable alternative interpretations to currently conflictive views on the biology, clinical initiation and progression of AD [2, 3].

Footnotes

ACKNOWLEDGMENTS

Special thanks are given to all volunteer subjects for their generous participation in this project. Our appreciation also to Dr. N. Satyamurthy and his Cyclotron staff for invaluable help and advice, John Williams of the Nuclear Medicine Clinic for support with scanning protocols, and Dr. Vladimir Kepe for radiosynthesis, initial PET scan analyses, and helpful discussions.

This study was supported by UCLA ADRC (NIH grant P50 AG 16570) and the Dominantly Inherited Alzheimer Network (NIH grant U19AG032438). JRB gratefully acknowledges support from the Elizabeth and Thomas Plott Endowment in Gerontology. No company provided support of any kind for this study.

Authors’ disclosures available online ().

The supplementary material is available in the electronic version of this article: .

References

Klunk

, Engler

, Nordberg

, Wang

, Blomqvist

, Holt

, Bergstrom

, Savitcheva

, Huang

, Estrada

, Ausen

, Debnath

, Barletta

, Price

, Sandell

, Lopresti

, Wall

, Koivisto

, Antoni

, Mathis

, Langstrom

(2004) Imaging brain amyloid in Alzheimer’s disease with Pittsburgh Compound-B. Ann Neurol 55, 306–319.

Kepe

, Moghbel

, Langstrom

, Zaidi

, Vinters

, Huang

, Satyamurthy

, Doudet

, Mishani

, Cohen

, Hoilund-Carlsen

, Alavi

, Barrio

(2013) Amyloid-beta positron emission tomography imaging probes: A critical review. J Alzheimers Dis 36, 613–631.

Jack

Jr. , Barrio

, Kepe

(2013) Cerebral amyloid PET imaging in Alzheimer’s disease. Acta Neuropathol 126, 643–657.

Mathis

, Holt

, Wang

, Huang

, Debnath

, Shao

, Klunk

(2004) Species-dependent metabolism of the amyloid imaging agent [C-11] PIB. J Nucl Med 45, 114P.

Suzuki

, Kodama

(1983) Moyamoya disease–a review. Stroke 14, 104–109.

Kazumata

, Tha

, Narita

, Kusumi

, Shichinohe

, Ito

, Nakayama

, Houkin

(2015) Chronic ischemia alters brain microstructural integrity and cognitive performance in adult moyamoya disease. Stroke 46, 354–360.

Kang

, Kim

, Phi

, Kim

, Wang

, Cho

, Kim

(2010) Plasma matrix metalloproteinases, cytokines and angiogenic factors in moyamoya disease. J Neurol Neurosurg Psychiatry 81, 673–678.

Scott

, Smith

(2009) Moyamoya disease and moyamoya syndrome. N Engl J Med 360, 1226–1237.

Straub

(2007) The complex role of estrogens in inflammation. Endocr Rev 28, 521–574.

10.

Ito

, Hayashi

, Yamada

, Kuzuya

, Naito

, Iguchi

(1995) Physiological concentration of estradiol inhibits polymorphonuclear leukocyte chemotaxis via a receptor mediated system. Life Sci 56, 2247–2253.

11.

Miller

, Feng

, Xing

, Weathington

, Blalock

, Chen

, Oparil

(2004) Estrogen modulates inflammatory mediator expression and neutrophil chemotaxis in injured arteries. Circulation 110, 1664–1669.

12.

Maret

, Coudert

, Garidou

, Foucras

, Gourdy

, Krust

, Dupont

, Chambon

, Druet

, Bayard

, Guery

(2003) Estradiol enhances primary antigen-specific CD4 T cell responses and Th1 development in vivo. Essential role of estrogen receptor alpha expression in hematopoietic cells. Eur J Immunol 33, 512–521.

13.

McGeachy

, Bak-Jensen

, Chen

, Tato

, Blumenschein

, McClanahan

, Cua

(2007) TGF-beta and IL-6 drive the production of IL-17 and IL-10 by T cells and restrain T(H)-17 cell-mediated pathology. Nat Immunol 8, 1390–1397.

14.

Chen

, Fan

, Zhang

, Liu

, Li

, Ke

, Li

, You

(2015) Estradiol inhibits Th17 cell differentiation through inhibition of RORgammaT transcription by recruiting the ERalpha/REA complex to estrogen response elements of the RORgammaT promoter. J Immunol 194, 4019–4028.

15.

Zhang

, Varlamova

, Vargas

, Falany

, Leyh

(1998) Sulfuryl transfer: The catalytic mechanism of human estrogen sulfotransferase. J Biol Chem 273, 10888–10892.

16.

Falany

(1997) Enzymology of human cytosolic sulfotransferases. FASEB J 11, 206–216.

17.

Song

(2001) Biochemistry and reproductive endocrinology of estrogen sulfotransferase. Ann N Y Acad Sci 948, 43–50.

18.

Hobkirk

(1985) Steroid sulfotransferases and steroid sulfate sulfatases: Characteristics and biological roles. Can J Biochem Cell Biol 63, 1127–1144.

19.

Cole

, Keum

, Liu

, Small

, Satyamurthy

, Kepe

, Barrio

(2010) Specific estrogen sulfotransferase (SULT1E1) substrates and molecular imaging probe candidates. Proc Natl Acad Sci U S A 107, 6222–6227.

20.

Miki

, Nakata

, Suzuki

, Darnel

, Moriya

, Kaneko

, Hidaka

, Shiotsu

, Kusaka

, Sasano

(2002) Systemic distribution of steroid sulfatase and estrogen sulfotransferase in human adult and fetal tissues. J Clin Endocrinol Metab 87, 5760–5768.

21.

Wong

K-P

, Bergsneider

, Glenn

, Kepe

, Barrio

, Hovda

, Vespa

, Huang

S-C

(2015) A semi-automated workflow solution for multimodal neuroimaging: Application to patients with traumatic brain injury. Brain Informatics 3, 1–15.

22.

Kazumata

, Tha

, Narita

, Ito

, Shichinohe

, Ito

, Uchino

, Abumiya

(2016) Characteristics of diffusional kurtosis in chronic ischemia of adult moyamoya disease: Comparing diffusional kurtosis and diffusion tensor imaging. AJNR Am J Neuroradiol 37, 1432–1439.

23.

Yamashita

, Oka

, Tanaka

(1983) Histopathology of the brain vascular network in moyamoya disease. Stroke 14, 50–58.

24.

Okamoto

, Naito

, Fukuda

, Suzuki

, Takatama

(2018) Adult moyamoya disease associated with abundant phosphorylated tau accumulation in the brainstem: Report of a case with autopsy findings. Neuropathology 38, 315–320.

25.

Garcia-Segura

(2008) Aromatase in the brain: Not just for reroduction anymore. J Neuroendocrinol 20, 705–712.

26.

Salman

, Faye-Petersen

, Falany

(2011) Hydroxysteroid sulfotransferase 2B1b expression and localization in normal human brain. Horm Mol Biol Clin Investig 8, 445–454.

27.

Harris

, Waring

, Kirk

, Hughes

(2000) Sulfation of “estrogenic” alkylphenols and 17B-estradiol by human platelet phenol sulfotransferases. J Biol Chem 275, 159–166.

28.

Gamage

, Tsvetanov

, Duggleby

, McManus

, Martin

(2005) The structure of human SULT1A1 crystallized with estradiol. An insight into active site plasticity and substrate inhibition with multi-ring substrates. J Biol Chem 280, 41482–41486.

29.

Soriano

, Cowan

, Proctor

, Scott

(2002) Levels of soluble adhesion molecules are elevated in the cerebrospinal fluid of children with moyamoya syndrome. Neurosurgery 50, 544–549.

30.

Hsieh

, Jeng

, Lin

, Hu

, Yu

, Lien

, Peng

, Chen

, Tang

, Chi

, Tseng

, Chern

, Hsieh

, Bai

, Chen

, Chiou

(2012) Formosa Stroke Genetic Consortium Epistasis analysis for estrogen metabolic and signaling pathway genes on young ischemic stroke patients. PLoS One 7, e47773.

31.

Shimada

, Peterson

, Spees

(2010) Isolation of locally derived stem/progenitor cells from the peri-infarct area that do not migrate from the lateral ventricle after cortical stroke. Stroke 41, e552–560.

32.

Ridet

, Malhotra

, Privat

, Gage

(1997) Reactive astrocytes: Cellular and molecular cues to biological function. Trends Neurosci 20, 570–577.

33.

Hurley

, Olschowka

, O’Banion

(2002) Cyclooxygenase inhibition as a strategy to ameliorate brain injury. J Neurotrauma 19, 1–15.

34.

, Rowe

, Villemagne

, Zavala

, Ma

, Sahathevan

, O’Keefe

, Gong

, Gunawan

, Churilov

, Saunder

, Ackerman

, Tochon-Danguy

, Donnan

(2012) Subacute ischemic stroke is associated with focal 11C PiB positron emission tomography retention but not with global neocortical Abeta deposition. Stroke 43, 1341–134.

35.

Stankoff

, Freeman

, Aigrot

, Chardain

, Dolle

, Williams

, Galanaud

, Armand

, Lehericy

, Lubetzki

, Zalc

, Bottlaender

(2011) Imaging central nervous system myelin by positron emission tomography in multiple sclerosis using [methyl-(1)(1)C]-2-(4^′-methylaminophenyl)- 6-hydroxybenzothiazole. Ann Neurol 69, 673–680.

36.

Bitsch

, Schuchardt

, Bunkowski

, Kuhlmann

, Bruck

(2000) Acute axonal injury in multiple sclerosis. Correlation with demyelination and inflammation. Brain 123, 1174–1183.

37.

Bengel

, Minoshima

(2012) SNM highlights lectures. J Nucl Med 53, 15N–31N.

38.

Villemagne

, Mulligan

, Pejoska

, Ong

, Jones

, O’Keefe

, Chan

, Young

, Tochon-Danguy

, Masters

, Rowe

(2012) Comparison of 11C-PIB and 18F-Florbetaben for Aβ imaging in ageing and Alzheimer’s disease. Eur J Nucl Med Mol Imaging 39, 983–989.

39.

Klunk

, Wang

, Huang

, Debnath

, Holt

, Shao

, Hamilton

, Ikonomovic

, DeKosky

, Mathis

(2003) The binding of 2-(4^′-methylaminophenyl) benzothiazole to postmortem brain homogenates is dominated by the amyloid component. J Neurosci 23, 2086–2092.

40.

Starke

, Crowley

, Maltenfort

, Jabbour

, Gonzalez

, Tjoumakaris

, Randazzo

, Rosenwasser

, Dumont

(2012) Moyamoya disorder in the United States. Neurosurgery 71, 93–99.

41.

Fodstad

, Bodosi

, Forssell

, Perricone

(1996) Moyamoya disease in patients of Finno-Ugric origin. Br J Neurosurgery 10, 179–186.

42.

Kaufman

, Little

, Berkowitz

(1988) Recurrent intracranial hemorrhage in an adult with moyamoya disease: Case report, radiographic studies and pathology. Can J Neurol Sci 15, 430–434.

43.

Jack

Jr. , Knopman

, Jagust

, Petersen

, Weiner

, Aisen

, Shaw

, Vemuri

, Wiste

, Weigand

, Lesnick

, Pankratz

, Donohue

, Trojanowski

(2013) Tracking pathophysiological processes in Alzheimer’s disease: An updated hypothetical model of dynamic biomarkers. Lancet Neurol 12, 207–216.

44.

Nelson

, Alafuzoff

, Bigio

, Bouras

, Braak

, Cairns

, Castellani

, Crain

, Davies

, Del Tredici

, Duyckaerts

, Frosch

, Haroutunian

, Hof

, Hulette

, Hyman

, Iwatsubo

, Jellinger

, Jicha

, Kovari

, Kukull

, Leverenz

, Love

, Mackenzie

, Mann

, Masliah

, McKee

, Montine

, Morris

, Schneider

, Sonnen

, Thal

, Trojanowski

, Troncoso

, Wisniewski

, Woltjer

, Beach

(2012) Correlation of Alzheimer disease neuropathologic changes with cognitive status: A review of the literature. J Neuropathol Exp Neurol 71, 362–381.

45.

Sojkova

, Zhou

, An

, Kraut

, Ferrucci

, Wong

, Resnick

(2011) Longitudinal patterns of beta-amyloid deposition in nondemented older adults. Arch Neurol 68, 644–649.

Probing Estrogen Sulfotransferase-Mediated Inflammation with [ 11 C]-PiB in the Living Human Brain

Abstract

Background:

Objective:

Methods:

Results:

Conclusion:

Keywords

INTRODUCTION

MATERIALS AND METHODS

Patient cohorts

Imaging

Middle cerebral arterial occlusion (MCAO) stroke model

Statistical analysis

RESULTS

[11C]-PiB SRTM DVR in moyamoya syndrome

Ischemic condition and relative [11C]-PiB signal in the brain of moyamoya patients

DISCUSSION

Conclusions

Footnotes

ACKNOWLEDGMENTS

References

[¹¹C]-PiB SRTM DVR in moyamoya syndrome

Ischemic condition and relative [¹¹C]-PiB signal in the brain of moyamoya patients