Update March 2016

Featured Article

Dashkevich, A., et al. (2015). “Ischemia-reperfusion injury enhances lymphatic endothelial VEGFR3 and rejection in cardiac allografts.” Am J Transplant. [EPub 2015 Dec 21]

Organ damage and innate immunity during heart transplantation may evoke adaptive immunity with serious consequences. Because lymphatic vessels bridge innate and adaptive immunity, they are critical in immune surveillance; however, their role in ischemia-reperfusion injury (IRI) in allotransplantation remains unknown. We investigated whether the lymphangiogenic VEGF-C/VEGFR3 pathway during cardiac allograft IRI regulates organ damage and subsequent interplay between innate and adaptive immunity. We found that cardiac allograft IRI, within hours, increased graft VEGF-C expression and lymphatic vessel activation in the form of increased lymphatic VEGFR3 and adhesion protein expression. Pharmacological VEGF-C/VEGFR3 stimulation resulted in early lymphatic activation and later increase in allograft inflammation. In contrast, pharmacological VEGF-C/VEGFR3 inhibition during cardiac allograft IRI decreased early lymphatic vessel activation with subsequent dampening of acute and chronic rejection. Genetic deletion of VEGFR3 specifically in the lymphatics of the transplanted heart recapitulated the survival effect achieved by pharmacological VEGF-C/VEGFR3 inhibition. Our results suggest that tissue damage rapidly changes lymphatic vessel phenotype, which, in turn, may shape the interplay of innate and adaptive immunity. Importantly, VEGF-C/VEGFR3 inhibition during solid organ transplant IRI could be used as lymphatic-targeted immunomodulatory therapy to prevent acute and chronic rejection.

The authors explore the intricacies of allotransplant rejection with a focus on the role of the lymphatic VEGFC/VEGFR3 pathway in ischemia/reperfusion of cardiac allografts in rat and mouse models. Induction of adaptive immunity (delayed-type, antigen-specific immunity, mediated via antibody producing via B-cells and effector T-cells), is an unwanted consequence of allotransplantation. They demonstrate activation of VEGFC/VEGFR3 within hours of cardiac allograft ischemia-reperfusion injury.

Unique to allotransplantation is the inability to clear foreign antigen, and previous studies (referenced in this article) have demonstrated a correlation between lymphangiogenesis and acute and chronic solid organ transplant rejection. The studies in this article assess the role of VEGFC/VEGFR3 in allograft survival and rejection. The ischemia-reperfusion injury triggers an immediate innate immune response, activating VEGFC/VEGFR3, which could evolve into an adaptive immune response and organ rejection. Pretreatment of donor organs with VEGF-inhibitors (e.g. VEGF-C/D trap) was able to prevent the innate immune response as well as adaptive allograft rejection, fibrosis and vasculopathy. These findings suggest a potential mechanism for prevention of solid organ rejection by pretreatment of organs with VEGFC/VEGFR3 inhibitors.

Basic Science

Agollah, G. D., et al. (2015). “Dextran sulfate sodium-induced acute colitis impairs dermal lymphatic function in mice.” World J Gastroenterol 21(45): 12767–12777.

Davis, M. J. (2016). “Is nitric oxide important for the diastolic phase of the lymphatic contraction/relaxation cycle?” Proc Natl Acad Sci USA 113(2): E105.

Gibot, L., et al. (2015). “Cell-based approach for 3D reconstruction of lymphatic capillaries in vitro reveals distinct functions of HGF and VEGF-C in lymphangiogenesis.” Biomaterials 78: 129–139.

Regeneration of lymphatic vessels is important for treatment of various disorders of lymphatic system and for restoration of lymphatic function after surgery. We have developed a method for generating a human 3D lymphatic vascular construct. In this system, human lymphatic endothelial cells, co-cultured with fibroblasts, spontaneously organized into a stable 3D lymphatic capillary network without the use of any exogenous factors. In vitro-generated lymphatic capillaries exhibited the major molecular and ultra-structural features of native, human lymphatic microvasculature: branches in the three dimensions, wide lumen, blind ends, overlapping borders, adherens and tight junctions, anchoring filaments, lack of mural cells, and poorly developed basement membrane. Furthermore, we show that fibroblast-derived VEGF-C and HGF cooperate in the formation of lymphatic vasculature by activating ERK1/2 signaling, and demonstrate distinct functions of HGF/c-Met and VEGF-C/VEGFR-3 in lymphangiogenesis. This lymphatic vascular construct is expected to facilitate studies of lymphangiogenesis in vitro and it holds promise as a strategy for regeneration of lymphatic vessels and treatment of lymphatic disorders in various conditions.

Greiwe, L., et al. (2015). “The muscle contraction mode determines lymphangiogenesis differentially in rat skeletal and cardiac muscles by modifying local lymphatic extracellular matrix microenvironments.” Acta Physiol (Oxf). [EPub 2015 Nov 25].

Jang, D. H., et al. (2015). “Anti-inflammatory and lymphangiogenetic effects of low-level laser therapy on lymphedema in an experimental mouse tail model.” Lasers Med Sci. [EPub 2015 Dec 29].

Johnson, O. W., et al. (2015). “The thoracic duct: clinical importance, anatomic variation, imaging, and embolization.” Eur Radiol. [EPub 2015 Dec 1].

Kang, G. J., et al. (2016). “Intravital imaging reveals dynamics of lymphangiogenesis and valvulogenesis.” Sci Rep 6: 19459.

Kim, S., et al. (2015). “Three-dimensional biomimetic model to reconstitute sprouting lymphangiogenesis in vitro.” Biomaterials 78: 115–128.

Koltowska, K., et al. (2015). “VEGFC regulates bipotential precursor division and Prox1 expression to promote lymphatic identity in zebrafish.” Cell Rep 13(9): 1828–1841.

Lymphatic vessels arise chiefly from preexisting embryonic veins. Genetic regulators of lymphatic fate are known, but how dynamic cellular changes contribute during the acquisition of lymphatic identity is not understood. We report the visualization of zebrafish lymphatic precursor cell dynamics during fate restriction. In the cardinal vein, cellular commitment is linked with the division of bipotential Prox1-positive precursor cells, which occurs immediately prior to sprouting angiogenesis. Following precursor division, identities are established asymmetrically in daughter cells; one daughter cell becomes lymphatic and progressively upregulates Prox1, and the other downregulates Prox1 and remains in the vein. Vegfc drives cell division and Prox1 expression in lymphatic daughter cells, coupling signaling dynamics with daughter cell fate restriction and precursor division.

Lamers, S. L., et al. (2015). “The meningeal lymphatic system: A route for HIV brain migration?” J Neurovirol. [EPub 2015 Nov 16].

Li, J., et al. (2015). “Establishment of lymphatic filarial specific IgG4 indirect ELISA detection method.” Int J Clin Exp Med 8(9): 16496–16503.

Loder, S., et al. (2016). “Lymphatic contribution to the cellular niche in heterotopic ossification.” Ann Surg. [EPub 2016 Jan 15].

Mitsi, M., et al. (2015). “Walking the line: A fibronectin fiber-guided assay to probe early steps of (lymph)angiogenesis.” PLoS One 10(12): e0145210.

Oka, S., et al. (2015). “Microsurgical anatomy of the spermatic cord and spermatic fascia: Distributions of lymphatics and sensory and autonomic nerves.” J Urol. [EPub 2015 Nov 25].

Qi, S. and J. Pan (2015). “Cell-based therapy for therapeutic lymphangiogenesis.” Stem Cells Dev 24(3): 271–283.

Rakocevic, J., et al. (2015). “Co-expression of vascular and lymphatic endothelial cell markers on early endothelial cells present in aspirated coronary thrombi from patients with ST-elevation myocardial infarction.” Exp Mol Pathol 100(1): 31–38.

Rossi, E., et al. (2015). “Endoglin regulates mural cell adhesion in the circulatory system.” Cell Mol Life Sci. [EPub].

Schrodl, F., et al. (2015). “Lymphatic markers in the adult human choroid.” Invest Ophthalmol Vis Sci 56(12): 7406–7416.

Teijeira, A. and C. Halin (2015). “Editorial: Breaching their way through: Neutrophils destroy intercellular junctions to transmigrate rapidly across lymphatic endothelium.” J Leukoc Biol 98(6): 880–882.

Yang, J. F., et al. (2015). “Understanding lymphangiogenesis in knockout models, the cornea, and ocular diseases for the development of therapeutic interventions.” Surv Ophthalmol. [EPub 2015 Dec 16].

Zawieja, S. D., et al. (2015). “Blunted flow-mediated responses and diminished nitric oxide synthase expression in lymphatic thoracic ducts of a rat model of metabolic syndrome.” Am J Physiol Heart Circ Physiol: ajpheart 00664 02015.

Zhang, L. M., et al. (2016). “Nitric oxide regulates the lymphatic reactivity following hemorrhagic shock through ATP-sensitive potassium channel.” Shock. [EPub 2016 Jan 8].

Lymphatic reactivity has been shown to exhibit a biphasic change following hemorrhagic shock, and nitric oxide (NO) is involved in this process. However, the precise mechanism responsible for NO regulation of the lymphatic reactivity along with the progression of hemorrhagic shock is unclear. Therefore, the present study was to investigate how NO participates in regulating the shock-induced biphasic changes in lymphatic reactivity and its underlying mechanisms. First, the expressions or contents of inducible NO synthase (iNOS), nitrite plus nitrate and elements of cAMP-PKA-KATP and cGMP-PKG-KATP pathway in thoracic ducts tissue were assessed. The results revealed that levels of nitrite plus nitrate, cAMP, cGMP, p-PKA and p-PKG were increased gradually along with the process of shock. Second, the roles of cAMP-PKA-KATP and cGMP-PKG-KATP in NO regulating lymphatic response to gradient substance P were evaluated with an isolated lymphatic perfusion system. The results showed that the NOS substrate (L-Arg), PKA donor (8-Br-cAMP) decreased the reactivity of shock 0.5 h-lymphatics, and that the PKA inhibitor (H-89) and KATP inhibitor (glibenclamide) restrained the effects of L-Arg while glibenclamide abolished the effects of 8-Br-cAMP. Meanwhile, NOS antagonist (L-NAME), PKG inhibitor (KT-5823), and soluble guanylate cyclase inhibitor (ODQ) increased the reactivity of shock 2 h-lymphatics, whereas KATP opener (pinacidil) inhibited these elevated effects induced by either L-NAME, ODQ or KT-5823. Taken together, these results indicate that NO regulation of lymphatic reactivity during shock involves both cAMP-PKA-KATP and cGMP-PKG-KATP pathways. These findings have potential significance for the treatment of hemorrhagic shock through regulating lymphatic reactivity.

Clinical

Bastaki, F., et al. (2015). “A novel SOX18 mutation uncovered in Jordanian patient with hypotrichosis-lymphedema-telangiectasia syndrome by Whole Exome Sequencing.” Mol Cell Probes. [EPub 2015 Nov 26].

El Mouhadi, S., et al. (2015). “Plastic bronchitis related to idiopathic thoracic lymphangiectasia. Noncontrast magnetic resonance lymphography.” Am J Respir Crit Care Med 192(5): 632–633.

Franchini, M., Lippi G. (2015). “Thalidomide for hereditary haemorrhagic telangiectasia.” Lancet Haematol 2(11): e457–458.

Hos, D., et al. (2015). “IL-10 indirectly regulates corneal lymphangiogenesis and resolution of inflammation via macrophages.” Am J Pathol. [EPub Nov 19].

Jackson, C. C., et al. (2015). “A multiplex kindred with Hennekam Syndrome due to homozygosity for a CCBE1 mutation that does not prevent protein expression.” J Clin Immunol. [EPub 2015 Dec 19].

Jeon, J. Y., et al. (2016). “Three-dimensional isotropic fast spin-echo MR lymphangiography of T1-weighted and intermediate-weighted pulse sequences in patients with lymphoedema.” Clin Radiol 71(1): e56–63.

Tashiro, K., et al. (2015). “Proximal and distal patterns: Different spreading patterns of indocyanine green lymphography in secondary lower extremity lymphedema.” J Plast Reconstr Aesthet Surg. [EPub 2015 Nov 5].

Thomas, A. C., et al. (2016). “Mosaic activating mutations in GNA11 and GNAQ are associated with phakomatosis pigmentovascularis and extensive dermal melanocytosis.” J Invest Dermatol. [EPub 2016 Jan 14].

Torrisi, J. S., et al. (2016). “Inhibition of inflammation and iNOS improves lymphatic function in obesity.” Sci Rep 6: 19817.

Vlahu, C. A., et al. (2015). “Lymphangiogenesis and lymphatic absorption are related and increased in chronic kidney failure, independent of exposure to dialysis solutions.” Adv Perit Dial 31: 21–25.

Oncology

Abellan-Pose, R., et al. (2015). “Lymphatic targeting of nanosystems for anticancer drug therapy.” Curr Pharm Des. [EPub 2015 Dec 16].

The lymphatic system represents a major route of dissemination in metastatic cancer. Given the lack of selectivity of conventional chemotherapy to prevent lymphatic metastasis, in the last years there has been a growing interest in the development of nanocarriers showing lymphotropic characteristics. The goal of this lympho-targeting strategy is to facilitate the delivery of anticancer drugs to the lymph node-resident cancer cells, thereby enhancing the effectiveness of the anti-cancer therapies. This article focuses on the nanosystems described so far for the active or passive targeting of oncological drugs to the lymphatic circulation. To understand the design and performance of these nanosystems, we will discuss first the physiology of the lymphatic system and how physiopathological changes associated to tumor growth influence the biodistribution of nanocarriers. Second, we provide evidence on how the tailoring of the physicochemical characteristics of nanosystems, i.e. particle size, surface charge and hydrophilicity, allows the modulation of their access to the lymphatic circulation. Finally, we provide an overview of the relationship between the biodistribution and anti-metastatic activity of the nanocarriers loaded with oncological drugs, and illustrate the most promising active targeting approaches investigated so far.

Chandrasekaran, S., et al. (2016). “Super natural killer cells that target metastases in the tumor draining lymph nodes.” Biomaterials 77: 66–76.

HC, V. A. N. W., et al. (2015). “Comparison of methods to identify lymphatic and blood vessel invasion and their prognostic value in patients with primary operable colorectal cancer.” Anticancer Res 35(12): 6457–6463.

Kato, S., et al. (2015). “A novel treatment method for lymph node metastasis using a lymphatic drug delivery system with nano/microbubbles and ultrasound.” J Cancer 6(12): 1282–1294.

Park, K. J., et al. (2016). “Prospero homeobox 1 mediates the progression of gastric cancer by inducing tumor cell proliferation and lymphangiogenesis.” Gastric Cancer. [EPub 2016 Jan 12].

BACKGROUND: Prospero homeobox 1 (PROX1) functions as a tumor suppressor gene or an oncogene in various cancer types. However, the distinct function of PROX1 in gastric cancer is unclear. We determined whether PROX1 affected the oncogenic behavior of gastric cancer cells and investigated its prognostic value in patients with gastric cancer. METHODS: A small interfering RNA against PROX1 was used to silence PROX1 expression in gastric cancer cell lines AGS and SNU638. Expression of PROX1 in gastric cancer tissues was investigated by performing immunohistochemistry. Apoptosis, proliferation, angiogenesis, and lymphangiogenesis were determined by performing the TUNEL assay and immunohistochemical staining for Ki-67, CD34, and D2-40. RESULTS: PROX1 knockdown induced apoptosis by activating cleaved caspase-3, caspase-7, caspase-9, and poly(ADP-ribose) polymerase, and by decreasing the expression of anti-apoptotic proteins Bcl-2 and Bcl-xL. PROX1 knockdown also suppressed tumor cell proliferation. In addition, PROX1 knockdown decreased lymphatic endothelial cell invasion and tube formation and the expression of vascular endothelial growth factor (VEGF)-C and -D and cyclooxygenase (COX)-2. However, PROX1 knockdown only decreased umbilical vein endothelial cell invasion, not tube formation. The mean Ki-67 labeling index and lymphatic vessel density value of PROX1-positive tumors were significantly higher than those of PROX1-negative tumors. However, no significant difference was observed between PROX1 expression and apoptotic index or microvessel density. PROX1 expression was significantly associated with age, cell differentiation, lymph node metastasis, cancer stage, and poor survival. CONCLUSIONS: These results indicate that PROX1 mediates the progression of gastric cancer by inducing tumor cell proliferation and lymphangiogenesis.

Sautter-Bihl, M. L. and F. Sedlmayer (2015). “Radiotherapy of the lymphatic pathways in early breast cancer.” Breast Care (Basel) 10(4): 254–258.

Sugimoto, S., et al. (2015). “The Ki-67 labeling index and lymphatic/venous permeation predict the metastatic potential of rectal neuroendocrine tumors.” Surg Endosc. [2015 Dec 30].

Vidal, M., et al. (2015). “Correlation between theoretical anatomical patterns of lymphatic drainage and lymphoscintigraphy findings during sentinel node detection in head and neck melanomas.” Eur J Nucl Med Mol Imaging. [EPub Nov 19].

Wakisaka, N., et al. (2015). “Primary tumor-secreted lymphangiogenic factors induce pre-metastatic lymphvascular niche formation at sentinel lymph nodes in oral squamous cell carcinoma.” PLoS One 10(12): e0144056.

Zhou, Z., et al. (2015). “A protein-corona-free T1-T2 dual-modal contrast agent for accurate imaging of lymphatic tumor metastasis.” ACS Appl Mater Interfaces 7(51): 28286–28293.

Vascular Anomalies

Bertoni, N., et al. (2016). “Integrative meta-analysis identifies microRNA-regulated networks in infantile hemangioma.” BMC Med Genet 17(1): 4.

BACKGROUND: Hemangioma is a common benign tumor in the childhood; however our knowledge about the molecular mechanisms of hemangioma development and progression are still limited. Currently, microRNAs (miRNAs) have been shown as gene expression regulators with an important role in disease pathogenesis. Our goals were to identify miRNA-mRNA expression networks associated with infantile hemangioma. METHODS: We performed a meta-analysis of previously published gene expression datasets including 98 hemangioma samples. Deregulated genes were further used to identify microRNAs as potential regulators of gene expression in infantile hemangioma. Data were integrated using bioinformatics methods, and genes were mapped in proteins, which were then used to construct protein-protein interaction networks. RESULTS: Deregulated genes play roles in cell growth and differentiation, cell signaling, angiogenesis and vasculogenesis. Regulatory networks identified included microRNAs miR-9, miR-939 and let-7 family; these microRNAs showed the most number of interactions with deregulated genes in infantile hemangioma, suggesting that they may have an important role in the molecular mechanisms of disease. Additionally, results were used to identify drug-gene interactions and druggable gene categories using Drug-Gene Interaction Database. We show that microRNAs and microRNA-target genes may be useful biomarkers for the development of novel therapeutic strategies for patients with infantile hemangioma. CONCLUSIONS: microRNA-regulated pathways may play a role in infantile hemangioma development and progression and may be potentially useful for future development of novel therapeutic strategies for patients with infantile hemangioma.

Bostrom, K. I., et al. (2015). “Matrix Gla protein limits pulmonary arteriovenous malformations in ALK1 deficiency.” Eur Respir J 45(3): 849–852.

Cheufou, D. H., et al. (2015). “Pulmonary manifestation of a condition resembling Kasabach-Merritt syndrome in a woman with abdominal angiomatosis associated with consumptive coagulopathy–surgical management: A case report.” J Med Case Rep 9: 107.

Chinnadurai, S., et al. (2016). “Pharmacologic interventions for infantile hemangioma: A meta-analysis.” Pediatrics. [EPub 2016 Jan 15.].

Couto, J. A., et al. (2015). “A somatic MAP3K3 mutation is associated with verrucous venous malformation.” Am J Hum Genet 96(3): 480–486.

Filippi, L., et al. (2015). “Infantile hemangiomas, retinopathy of prematurity and cancer: a common pathogenetic role of the beta-adrenergic system.” Med Res Rev 35(3): 619–652.

Hashizume, N., et al. (2016). “Clinical efficacy of herbal medicine for pediatric lymphatic malformations: A pilot study.” Pediatr Dermatol. [EPub 2016 Jan 17].

Heit, J. J., et al. (2016). “Guidelines and parameters: Percutaneous sclerotherapy for the treatment of head and neck venous and lymphatic malformations.” J Neurointerv Surg. [EPub 2016 Jan 22].

Invernizzi, R., et al. (2015). “Efficacy and safety of thalidomide for the treatment of severe recurrent epistaxis in hereditary haemorrhagic telangiectasia: Results of a non-randomised, single-centre, phase 2 study.” Lancet Haematol 2(11): e465–473.

Kar, S., et al. (2016). “Role of Delta-Notch signaling in cerebral cavernous malformations.” Neurosurg Rev. [EPub 2016 Jan 16].

Cerebral cavernous malformations (CCM) commonly known as cavernous hemangioma are associated with abnormally enlarged thin-walled blood vessels. As a result, these dilated capillaries are prone to leakage and result in hemorrhages. Clinically, such hemorrhages lead to severe headaches, focal neurological deficits, and epileptic seizures. CCM is caused by loss of function mutations in one of the three well-known CCM genes: Krev interaction trapped 1 (KRIT1), OSM, and programmed cell death 10 (PDCD10). Loss of CCM genes have been shown to be synergistically related to decreased Notch signaling and excessive angiogenesis. Despite recent evidences indicating that Notch signaling plays a pivotal role in regulating angiogenesis, the role of Notch in CCM development and progression is still not clear. Here, we provide an update literature review on the current knowledge of the structure of Notch receptor and its ligands, its relevance to angiogenesis and more precisely to CCM pathogenesis. In addition to reviewing the current literatures, this review will also focus on the cross talk between Delta-Notch and vascular endothelial growth factor (VEGF) signaling in angiogenesis and in CCM pathogenesis. Understanding the role of Notch signaling in CCM development and progression might help provide a better insight for novel anti-angiogenic therapies.

Limaye, N., et al. (2015). “Somatic activating PIK3CA mutations cause venous malformation.” Am J Hum Genet 97(6): 914–921.

Somatic mutations in TEK, the gene encoding endothelial cell tyrosine kinase receptor TIE2, cause more than half of sporadically occurring unifocal venous malformations (VMs). Here, we report that somatic mutations in PIK3CA, the gene encoding the catalytic p110alpha subunit of PI3K, cause 54% (27 out of 50) of VMs with no detected TEK mutation. The hotspot mutations c.1624G>A, c.1633G>A, and c.3140A>G (p.Glu542Lys, p.Glu545Lys, and p.His1047Arg), frequent in PIK3CA-associated cancers, overgrowth syndromes, and lymphatic malformation (LM), account for >92% of individuals who carry mutations. Like VM-causative mutations in TEK, the PIK3CA mutations cause chronic activation of AKT, dysregulation of certain important angiogenic factors, and abnormal endothelial cell morphology when expressed in human umbilical vein endothelial cells (HUVECs). The p110alpha-specific inhibitor BYL719 restores all abnormal phenotypes tested, in PIK3CA- as well as TEK-mutant HUVECs, demonstrating that they operate via the same pathogenic pathways. Nevertheless, significant genotype-phenotype correlations in lesion localization and histology are observed between individuals with mutations in PIK3CA versus TEK, pointing to gene-specific effects.

Lindhurst, M. J., et al. (2015). “Repression of AKT signaling by ARQ 092 in cells and tissues from patients with Proteus syndrome.” Sci Rep 5: 17162.

A somatic activating mutation in AKT1, c.49G>A, pGlu17Lys, that results in elevated AKT signaling in mutation-positive cells, is responsible for the mosaic overgrowth condition, Proteus syndrome. ARQ 092 is an allosteric pan-AKT inhibitor under development for treatment in cancer. We tested the efficacy of this drug for suppressing AKT signaling in cells and tissues from patients with Proteus syndrome. ARQ 092 reduced phosphorylation of AKT and downstream targets of AKT in a concentration-dependent manner in as little as two hours. While AKT signaling was suppressed with ARQ 092 treatment, cells retained their ability to respond to growth factor stimulation by increasing pAKT levels proportionally to untreated cells. At concentrations sufficient to decrease AKT signaling, little reduction in cell viability was seen. These results indicate that ARQ 092 can suppress AKT signaling and warrants further development as a therapeutic option for patients with Proteus syndrome.

Lougaris, V., et al. (2016). “Proteus syndrome: Evaluation of the immunological profile.” Orphanet J Rare Dis 11(1): 3.

MacIsaac, Z. M., et al. (2016). “Treatment for infantile hemangiomas: Selection criteria, safety, and outcomes using oral propranolol during the early phase of propranolol use for hemangiomas.” J Craniofac Surg 27(1): 159–162.

Marnat, G., et al. (2015). “VEGFA targeting in capillary hemangiomas.” J Neurooncol 125(2): 443–444.

McCormick, A., et al. (2016). “A case of a central conducting lymphatic anomaly responsive to sirolimus.” Pediatrics 137(1): 1–4.

Munabi, N. C., et al. (2016). “Propranolol targets hemangioma stem cells via cAMP and mitogen-activated protein kinase regulation.” Stem Cells Transl Med 5(1): 45–55.

Infantile hemangiomas (IHs) are the most common vascular tumor and arise from a hemangioma stem cell (HemSC). Propranolol has proved efficacious for problematic IHs. Propranolol is a nonselective beta-adrenergic receptor (betaAR) antagonist that can lower cAMP levels and activate the mitogen-activated protein kinase (MAPK) pathway downstream of betaARs. We found that HemSCs express beta1AR and beta2AR in proliferating IHs and determined the role of these betaARs and the downstream pathways in mediating propranolol's effects. In isolated HemSCs, propranolol suppressed cAMP levels and activated extracellular signal-regulated kinase (ERK)1/2 in a dose-dependent fashion. Propranolol, used at doses of <10(-4) M, reduced cAMP levels and decreased HemSC proliferation and viability. Propranolol at >/ = 10(-5) M reduced cAMP levels and activated ERK1/2, and this correlated with HemSC apoptosis and cytotoxicity at >/ = 10(-4) M. Stimulation with a betaAR agonist, isoprenaline, promoted HemSC proliferation and rescued the antiproliferative effects of propranolol, suggesting that propranolol inhibits betaAR signaling in HemSCs. Treatment with a cAMP analog or a MAPK inhibitor partially rescued the HemSC cell viability suppressed by propranolol. A selective beta2AR antagonist mirrored propranolol's effects on HemSCs in a dose-dependent fashion, and a selective beta1AR antagonist had no effect, supporting a role for beta2AR signaling in IH pathobiology. In a mouse model of IH, propranolol reduced the vessel caliber and blood flow assessed by ultrasound Doppler and increased activation of ERK1/2 in IH cells. We have thus demonstrated that propranolol acts on HemSCs in IH to suppress proliferation and promote apoptosis in a dose-dependent fashion via beta2AR perturbation, resulting in reduced cAMP and MAPK activation. SIGNIFICANCE: The present study investigated the action of propranolol in infantile hemangiomas (IHs). IHs are the most common vascular tumor in children and have been proposed to arise from a hemangioma stem cell (HemSC). Propranolol, a nonselective beta-adrenergic receptor (betaAR) antagonist, has proven efficacy; however, understanding of its mechanism of action on HemSCs is limited. The presented data demonstrate that propranolol, via betaAR perturbation, dose dependently suppresses cAMP levels and activated extracellular signal-regulated kinase 1/2. Furthermore, propranolol acts via perturbation of beta2AR, and not beta1AR, although both receptors are expressed in HemSCs. These results provide important insight into propranolol's action in IHs and can be used to guide the development of more targeted therapy.

Noguera-Morel, L., et al. (2016). “Net-like superficial vascular malformation: Clinical description and evidence for lymphatic origin.” Br J Dermatol. [EPub 2016 Jan 22.]

We describe a distinctive presentation of LM that has not been previously recognized. Three children had progressive skin lesions consisting of large, irregularly shaped, bright red to red/brown to purple patches with a finely reticulated pattern. Dermoscopy showed deep red, reticulated telangiectatic vessels. Skin biopsies showed dilated thin-walled vessels in the upper dermis lined by a single layer of endothelial cells with prominent nuclei protruding into the lumens. Immunohistochemistry for the lymphatic marker podoplanin (D2-40) was positive in all cases. The patients described do not adequately fit other described types of cutaneous LM. We propose that this is a distinct, not formerly described type of LM, for which we propose the term Lymphatic Net-like Malformation (LNM). This article is protected by copyright. All rights reserved.

Passali, G. C., et al. (2015). “An old drug for a new application: Carbazochrome-sodium-sulfonate in HHT.” J Clin Pharmacol 55(5): 601–602.

Peacock, H. M., et al. (2015). “Arteriovenous malformations in hereditary haemorrhagic telangiectasia: Looking beyond ALK1-NOTCH interactions.” Cardiovasc Res. [EPub 2015 Dec 8].

Peng, H. L., et al. (2015). “Thalidomide effects in patients with hereditary hemorrhagic telangiectasia during therapeutic treatment and in Fli-EGFP transgenic zebrafish model.” Chin Med J (Engl) 128(22): 3050–3054.

BACKGROUND: Hereditary hemorrhagic telangiectasia (HHT) is an autosomal dominant disease characterized by recurrent epistaxis, mucocutaneous telangiectasia, and arteriovenous malformations. The efficacy of traditional treatments for HHT is very limited. The aim of this study was to investigate the therapeutic role of thalidomide in HHT patients and the effect in FLI-EGFP transgenic zebrafish model. METHODS: HHT was diagnosed according to Shovlin criteria. Five HHT patients were treated with thalidomide (100 mg/d). The Epistaxis Severity Score (ESS), telangiectasia spots, and hepatic computed tomography angiography (CTA) were used to assess the clinical efficacy of thalidomide. The Fli-EGFP zebrafish model was investigated for the effect of thalidomide on angiogenesis. Dynamic real-time polymerase chain reaction assay, ELISA and Western blotting from patient's peripheral blood mononuclear cells and plasma were used to detect the expression of transforming growth factor beta 3 (TGF-beta3) messenger RNA (mRNA) and vascular endothelial growth factor (VEGF) protein before and after 6 months of thalidomide treatment. RESULTS: The average ESS before and after thalidomide were 6.966 +/− 3.093 and 1.799 +/− 0.627, respectively (P = 0.009). The “telangiectatic spot” on the tongue almost vanished; CTA examination of case 2 indicated a smaller proximal hepatic artery and decreased or ceased hepatic artery collateral circulation. The Fli-EGFP zebrafish model manifested discontinuous vessel development and vascular occlusion (7 of 10 fishes), and the TGF-beta3 mRNA expression of five patients was lower after thalidomide therapy. The plasma VEGF protein expression was down-regulated in HHT patients. CONCLUSIONS: Thalidomide reverses telangiectasia and controls nosebleeds by down-regulating the expression of TGF-beta3 and VEGF in HHT patients. It also leads to vascular remodeling in the zebrafish model.

Qiu, Y., et al. (2015). “Eighteen cases of soft tissue atrophy after intralesional bleomycin a5 injections for the treatment of infantile hemangiomas: A long-term follow-up.” Pediatr Dermatol 32(2): 188–191.

Quan, A. V., et al. (2015). “Retinal vein-to-vein anastomoses in Sturge-Weber syndrome documented by ultra-widefield fluorescein angiography.” J AAPOS 19(3): 270–272.

Sulzberger, L., et al. (2015). “Serum levels of renin, angiotensin-converting enzyme and angiotensin II in patients treated by surgical excision, propranolol and captopril for problematic proliferating infantile haemangioma.” J Plast Reconstr Aesthet Surg. [EPub 2015 Oct 26].

The role of the renin-angiotensin system (RAS) in the biology of infantile haemangioma (IH) and its accelerated involution induced by beta-blockers was first proposed in 2010. This led to the first clinical trial in 2012 using low-dose captopril, an angiotensin-converting enzyme (ACE) inhibitor, demonstrating a similar response in these tumours. This study aimed to compare serial serum levels of the components of the RAS in patients before and after surgical excision, propranolol or captopril treatment for problematic proliferating IH. Patients with problematic proliferating IH underwent measurements of serum levels of plasma renin activity (PRA), ACE and angiotensin II (ATII) before, and 1–2 and 6 months following surgical excision, propranolol or captopril treatment. This study included 27 patients undergoing surgical excision (n = 8), propranolol (n = 11) and captopril (n = 8) treatment. Treatment with either surgical excision or propranolol resulted in significant decrease in the mean levels of PRA. Surgical excision or captopril treatment led to significant decline in the mean levels of ATII. All three treatment modalities had no significant effect on the mean levels of ACE. This study demonstrates the effect of surgical excision, propranolol and captopril treatment in lowering the levels of PRA and ATII, but not ACE, supporting a mechanistic role for the RAS in the biology of IH.

Theiler, M., et al. (2016). “Breast hypoplasia as a complication of an untreated infantile hemangioma.” Pediatr Dermatol. [EPub 2016 Jan 14].

Yun, Y. J., et al. (2015). “A prospective study to assess the efficacy and safety of oral propranolol as first-line treatment for infantile superficial hemangioma.” Korean J Pediatr 58(12): 484–490.

Zaher, H., et al. (2015). “Propranolol versus captopril in the treatment of infantile hemangioma (IH): A randomized controlled trial.” J Am Acad Dermatol. [EPub 2015 Dec 11]

Zhao, S. F., et al. (2015). “Gorham disease of the mandible.” J Craniofac Surg 26(2): e160–162.

Zuccolo, E., et al. (2015). “Constitutive store-operated Ca2+ entry leads to enhanced nitric oxide production and proliferation in infantile hemangioma-derived endothelial colony forming cells.” Stem Cells Dev. [EPub 2015 Dec 9].

Clonal endothelial progenitor cells (EPCs) have been implicated in the aberrant vascular growth that features infantile hemangioma (IH), the most common benign vascular tumor in the childhood that may cause ulceration, bleeding and/or permanent disfigurement. Endothelial colony forming cells (ECFCs), truly endothelial EPCs endowed with clonal ability and capable of forming patent vessels in vivo, remodel their Ca2+ toolkit in tumor-derived patients to acquire an adaptive advantage. Particularly, they up-regulate the pro-angiogenic store-operated Ca2+ entry (SOCE) pathway due to the over-expression of its underlying components, i.e. Stromal Interaction Molecule 1 (Stim1), Orai1 and Transient Receptor Potential Canonical 1 (TRPC1). The present work was undertaken to assess whether and how the Ca2+ signalosome is altered in IH-ECFCs by employing Ca2+ and nitric oxide (NO) imaging, real-time polymerase chain reaction, western blotting and functional assays. IH-ECFCs display a lower intracellular Ca2+ release in response to either pharmacological (i.e. cyclopiazonic acid) or physiological (i.e. ATP and VEGF) stimulation. Conversely, Stim1, Orai1 and TRPC1 transcripts and proteins are normally expressed in these cells and mediate a constitutive SOCE which is sensitive to BTP-2, La3+ and Pyr6 and recharges the intracellular Ca2+ pool. The resting SOCE in IH-ECFCs is also associated to an increase in their proliferation rate and in the basal production of NO as compared to normal cells. Likewise, the pharmacological blockade of SOCE and NO synthesis blocks IH-ECFC growth. Collectively, these data indicate that the constitutive SOCE activation enhances IH-ECFC proliferation by augmenting basal NO production and sheds novel light on the molecular mechanisms of IH.