Activation of Nuclear Factor-kappa B in Endothelial Cells of Chronic Subdural Hematoma Outer Membranes.

Background: Chronic subdural hematoma (CSDH) is considered an angiogenic and inflammatory disease. Nuclear factor-kappa B (NF-κB) induces the production of inflammatory cytokines and adhesion molecules, which play an essential role in angiogenesis and inflammation. Recently, the double-stranded RNA-activated protein kinase (PKR) was shown to directly interact with NF-κB subunits to influence its transcriptional activity.

Objective: To examine the expression of NF-κB signaling pathway components and PKR in CSDH outer membranes.

Methods: Eight patients whose outer membranes were successfully obtained during trepanation surgery were included in this study. The IκBα, IKKβ, IKKγ, NF-κB, phosphorylated ( p )-NF-κB, and PKR expression levels were examined using western blotting analysis. NF-κB expression was also examined using immunohistochemistry. We investigated whether CSDH fluid could activate NF-κB in cultured endothelial cells in Vitro.

Results: The IκBα, IKKβ, IKKγ, and NF-κB levels were approximately the same. Additionally, p -NF-κB and PKR were detected at similar levels. Immunostaining showed that NF-κB was expressed in the vascular endothelium. p -NF-κB expression in endothelial cells was significantly induced immediately after treatment with CSDH fluid. Furthermore, NF-κB activation was significantly inhibited by treatment with antibodies directed against vascular endothelial growth factor.

Conclusion: PKR might activate NF-κB through vascular endothelial growth factor in endothelial cells, which might be associated with endothelial cell proliferation in the CSDH outer membrane. Thus, the NF-κB signaling pathway could play a critical role in CSDH growth.