Expression of Mitogen-Activated Protein Kinases in Chronic Subdural Hematoma Outer Membranes

Platelet-derived Growth Factor Activates Pericytes in the Microvessels of Chronic Subdural Hematoma Outer Membranes

Angiogenesis is one of the growth mechanisms of chronic subdural hematoma (CSDH). Pericytes have been implicated in the capillary sprouting during angiogenesis and are involved in brain ischemia and diabetic retinopathy. This study examined the pericyte expressions in CSDH outer membranes obtained during trepanation surgery. Eight samples of CSDH outer membranes and 35 samples of CSDH fluid were included. NG2, N-cadherin, VE-cadherin, Tie-2, endothelial nitric oxide synthase (eNOS), platelet-derived growth factor (PDGF) receptor-β (PDGFR-β), a well-known marker of pericytes, phosphorylated PDGFR-β at Tyr751, and β-actin expressions, were examined using western blot analysis. PDGFR-β, N-cadherin, and Tie-2 expression levels were also examined using immunohistochemistry. The concentrations of PDGF-BB in CSDH fluid samples were measured using enzyme-linked immunosorbent assay kits. NG2, N-cadherin, VE-cadherin, Tie-2, eNOS, PDGFR-β, and eNOS expressions in CSDH outer membranes were confirmed in all cases. Furthermore, phosphorylated PDGFR-β at Tyr751 was also detected. In addition, PDGFR-β, N-cadherin, and Tie-2 expressions were localized to the endothelial cells of the vessels within CSDH outer membranes by immunohistochemistry. The concentration of PDGF-BB in CSDH fluids was significantly higher than that in cerebrospinal fluid. These findings indicate that PDGF activates pericytes in the microvessels of CSDH outer membranes and suggest that pericytes are crucial in CSDH angiogenesis through the PDGF/PDGFR-β signaling pathway.

Angiogenesis in the Outer Membrane of Chronic Subdural Hematomas through Thrombin-Cleaved Osteopontin and the Integrin α9 and Integrin β1 Signaling Pathways

BACKGROUND

A chronic subdural hematoma (CSDH) is considered to be an inflammatory and angiogenic disease. The CSDH outer membrane, which contains inflammatory cells, plays an important role in CSDH development. Osteopontin (OPN) is an extracellular matrix protein that is cleaved by thrombin, generating the N-terminal half of OPN, which is prominently involved in integrin signal transduction. We explored the expression of the N-terminal half of OPN in CSDH fluid and the expression of integrins α9 and β1 and the downstream components of the angiogenic signaling pathways in the outer membrane of CSDHs.

METHODS

Twenty samples of CSDH fluid and eight samples of CSDH outer membrane were collected from patients suffering from CSDHs. The concentrations of the N-terminal half of OPN in CSDH fluid samples were measured using ELISA kits. The expression levels of integrins α9 and β1, vinculin, talin-1, focal adhesion kinase (FAK), paxillin, α-actin, Src and β-actin were examined by Western blot analysis. The expression levels of integrins α9 and β1, FAK and paxillin were also examined by immunohistochemistry. We investigated whether CSDH fluid could activate FAK in cultured endothelial cells in vitro.

RESULTS

The concentration of the N-terminal half of OPN in CSDH fluid was significantly higher than that in the serum. Western blot analysis confirmed the presence of these molecules. In addition, integrins α9 and β1, FAK and paxillin were localized in the endothelial cells of vessels within the CSDH outer membrane. FAK was significantly phosphorylated immediately after treatment with CSDH fluid.

CONCLUSION

Our data suggest that the N-terminal half of OPN in CSDH fluid promotes neovascularization in endothelial cells through integrins α9 and β1. The N-terminal half of OPN, which is part of the extracellular matrix, plays a critical role in the promotion of CSDHs.

Expression of high mobility group B1 and toll-like receptor-nuclear factor κB signaling pathway in chronic subdural hematomas

Chronic subdural hematoma (CSDH) is an angiogenic and inflammatory disease. Toll-like receptors (TLRs) transduce intracellular signals, resulting in the activation of nuclear factor κB (NF-κB), which leads to the production of inflammatory cytokines. High-mobility group box 1 (HMGB1) functions as a mediator of inflammatory responses through TLRs. In this study, we examined the expression of HMGB1 and components of the Toll-like receptor and NF-κB signaling pathways in the outer membrane of CSDH. Eight patients whose outer membrane was successfully obtained during trepanation surgery were included in this study. The expression of TLR4, myeloid differentiation factor 88 (MyD88), interleukin-1 receptor-associated kinase 4 (IRAK4), TNF receptor-associated factor 6 (TRAF6), TGFβ-activated kinase 1 (Tak1), interferon regulatory factors 3 (IRF3), IκB kinase β (IKKβ), IKKγ, IκBε, IκBα, NF-κB/p65 and β-actin was examined by Western blot analysis. The expression of TLR4, NF-κB/p65 and interleukin-6 (IL-6) was also examined by immunohistochemistry. The concentrations of HMGB1 and IL-6 in CSDH fluids were measured using ELISA kits. Above-mentioned molecules were detected in all cases. In addition, TLR4, NF-κB/p65 and IL-6 were localized in the endothelial cells of vessels within CSDH outer membranes. The concentrations of HMGB1 and IL-6 in CSDH fluids were significantly higher than that in the CSF and serum. There existed a correlation between the concentrations of HMGB1 and IL-6 in CSDH fluids. Our data suggest that HMGB1 in CSDH fluids produces the inflammatory cytokine IL-6 in endothelial cells through the Toll-like receptor and NF-κB signaling pathways. Anti-HMGB1 therapy might be a useful method to treat the growth of CSDH.

The Effect of Goreisan on the Prevention of Chronic Subdural Hematoma Recurrence: Multi-Center Randomized Controlled Study

The relatively high rate of post-operative recurrence in the treatment of chronic subdural hematoma (CSDH) is a significant problem. Goreisan is an herbal medicine that exhibits a hydragogue effect by inhibiting the expression of aquaporins, and its efficacy in preventing post-operative CSDH recurrence has been suggested by several case trials. This multi-center prospective randomized controlled trial was performed to investigate the preventative effect of goreisan on post-operative CSDH recurrence. Patients with symptomatic CSDH over 60 years old undergoing burr hole surgery were enrolled in this study. The patients were randomly allocated to the control group or the goreisan group, in which oral administration of goreisan (7.5 g daily) was continued for 12 weeks. The primary end-point was the post-operative recurrence rate at 12 weeks and the secondary end-point was hematoma volume reduction rates on computed tomography scan at 12 weeks. The analyses were performed not only on patients of all ages older than 60 years, but also on patients divided into those over or under 75 years old. One hundred and eighty patients were followed and analyzed (the control group, n = 88; the goreisan group, n = 92). The recurrence rates considering patients of all ages and patients under 75 years old were relatively low in the goreisan group but without a significant difference. The hematoma volume reduction rates showed no significant difference. Based on the results of the present study, a larger-scale study including more cases is necessary in future to confirm the efficacy of goreisan.

Expression of Autophagy Signaling Molecules in the Outer Membranes of Chronic Subdural Hematomas

Chronic subdural hematoma (CSDH) is fundamentally treatable, although it sometimes recurs. We observed, however, several cases of spontaneous resolution of CSDH outer membranes, even in a trabecular type of CSDH, after a trepanation surgical procedure. In this study, we examined the expression of molecules of the autophagy signaling pathway in CSDH outer membranes. Eight patients whose outer membranes were obtained successfully during trepanation were included in this study. By Western blot analysis, we examined the expression of mammalian target of rapamycin (mTOR); GβL; UNC-51-like kinase-1 (ULK1); Beclin-1; autophagy-related genes (Atg) 3, 5, 7, 12, 13, and 16L1β,α; the autophagy marker Light Chain3A/B (LC3A/B); and β-actin, which constitute the autophagy signaling pathway. The expression levels of Beclin-1, Atg12, and LC3A/B were also examined by immunohistochemistry. Almost all of these molecules could be detected in all samples. Beclin-1, Atg12, and LC3A/B were found to be localized in the endothelial cells of vessels and fibroblasts in CSDH. We detected molecules of the autophagy signaling pathway in CSDH outer membranes. Autophagy contributes to the tissue homeostatic process, maintaining cellular integrity by clearing debris. Our data suggest that autophagy might play an important role in the spontaneous resolution of CSDH. Therefore, these molecules may be novel therapeutic targets for the treatment of those with CSDH.

Expressions of Eotaxin-3, Interleukin-5, and Eosinophil-Derived Neurotoxin in Chronic Subdural Hematoma Fluids

Eosinophils induce inflammation by releasing cytokines and cytotoxic granule proteins. Infiltration of eosinophilic granulocytes occurs in the outer membrane of chronic subdural hematomas (CSDHs). Eosinophils play an important role in the growth of CSDHs. However, the manner in which eosinophils accumulate within CSDH fluid remains undetermined. In the current study, we assessed the expression of eosinophil chemoattractants in CSDH fluids according to growth stage of CSDHs and examined the correlation between the two. CSDH fluids were obtained from 38 patients during trepanation surgery. Ecalectin, eotaxin-3, interleukin-5 (IL-5), and eosinophil-derived neurotoxin (EDN) concentrations were measured using enzyme-linked immunosorbent assay kits. For use as controls, serum samples were collected from 5 healthy adults, and cerebrospinal fluid (CSF) samples were collected from 5 adults with unruptured aneurysms. The percentage of eosinophils (%eosinophil) in CSDH fluids was calculated using Giemsa staining. Concentrations of ecalectin, eotaxin-3, IL-5, and EDN were nearly equivalent in serum and CSF samples; however, their concentrations were high in CSDH fluids. In particular, ecalectin and EDN levels in CSDH fluids were significantly higher than those in serum and CSF. Levels of eotaxin-3, IL-5, EDN, and %eosinophil were significantly higher in laminar type of CSDH, whereas that of ecalectin was not. The correlations between eotaxin-3 and IL-5, IL-5 and EDN, and EDN and %eosinophil were statistically significant (p < 0.01). Our data suggest that eotaxin-3 is a chemoattractant of eosinophils. IL-5 induces the activation of eosinophils subsequent to degranulation of EDN into CSDH fluids. These factors may serve as novel therapeutic targets for managing CSDH.

Inhibitory Mechanism of the Outer Membrane Growth of Chronic Subdural Hematomas

We previously demonstrated that the inflammatory cytokine interleukin-6 (IL-6) activates the Janus kinase (JAK)-signal transducer and activator of transcription (STAT) signaling pathway in fibroblasts within the outer membranes of chronic subdural hematomas (CSDHs), and the activation of this pathway may induce CSDH outer membrane growth. The inhibitory system for this signal transduction pathway is unknown. CSDH fluids were obtained from 10 patients during trepanation surgery as the case group, and cerebrospinal fluid (CSF) samples were obtained from seven patients suffering from subarachnoid hemorrhage (SAH) on Day 1 as the control group. The concentrations of IL-6, soluble IL-6 receptor (sIL-6R), and soluble gp130 (sgp130) in CSDH fluid and CSF were measured using enzyme immunoassay kits. The co-localization of IL-6 and sgp130 in CSDH fluid was examined by immunoprecipitation. The expression levels of STAT3, JAK2, suppressor of cytokine signaling 3 (SOCS3), and protein inhibitor of activated Stat3 (PIAS3) in the outer membranes of CSDHs were examined by immunostaining. Soluble IL-6R and sgp130 concentrations in CSDH fluid were significantly higher than those in CSF after SAH. Sgp130 and IL-6 were co-immunoprecipitated from CSDH fluid. Immunostaining revealed STAT3, JAK2, SOCS3, and PIAS3 expression in fibroblasts located in the outer membranes of CSDHs. Soluble gp130 binds to IL-6/sIL-6R and acts as an antagonist of the JAK/STAT signaling pathway. SOCS3 also binds to JAK and inhibits its signaling pathway. In addition, PIAS3 regulates STAT3 activation. These factors might down-regulate the IL-6/JAK/STAT signaling pathway in fibroblasts within CSDH outer membranes. Therefore, these molecules may be novel therapeutic targets for the inhibition of CSDH growth.

Pathophysiology of chronic subdural haematoma: inflammation, angiogenesis and implications for pharmacotherapy

Chronic subdural haematoma (CSDH) is an encapsulated collection of blood and fluid on the surface of the brain. Historically considered a result of head trauma, recent evidence suggests there are more complex processes involved. Trauma may be absent or very minor and does not explain the progressive, chronic course of the condition. This review focuses on several key processes involved in CSDH development: angiogenesis, fibrinolysis and inflammation. The characteristic membrane surrounding the CSDH has been identified as a source of fluid exudation and haemorrhage. Angiogenic stimuli lead to the creation of fragile blood vessels within membrane walls, whilst fibrinolytic processes prevent clot formation resulting in continued haemorrhage. An abundance of inflammatory cells and markers have been identified within the membranes and subdural fluid and are likely to contribute to propagating an inflammatory response which stimulates ongoing membrane growth and fluid accumulation. Currently, the mainstay of treatment for CSDH is surgical drainage, which has associated risks of recurrence requiring repeat surgery. Understanding of the underlying pathophysiological processes has been applied to developing potential drug treatments. Ongoing research is needed to identify if these therapies are successful in controlling the inflammatory and angiogenic disease processes leading to control and resolution of CSDH.