Occludin degradation makes brain microvascular endothelial cells more vulnerable to reperfusion injury in vitro

AbstractIntracerebral hemorrhage is the most dangerous complication in tPA thrombolytic therapy for ischemic stroke, which occurs as a consequence of endothelial cell death at the blood brain barrier (BBB) during thrombolytic reperfusion. We have previously shown that cerebral ischemia induced rapid occludin degradation and BBB disruption. Here we demonstrated an important role of occludin degradation in facilitating the evolution of ischemic endothelial cells towards death. Cultured brain microvascular endothelial cells (bEnd.3 cells) were exposed to oxygen ‐glucose deprivation (OGD) or incubated with occludin siRNA or occludin AAV to achieve an occludin deficiency or overexpression status before exposing to reoxygenation (R) or TNF‐α treatment. Cell death was assessed by measuring lactate dehydrogenase release, TUNEL staining and flow cytometry a nalysis. Inhibition of OGD‐induced occludin degradation with SB‐3CT or overexpression of occludin with occludin AAV both significantly attenuated OGD/R‐induced apoptosis and pyroptosis in bEnd.3 cells. Consistently, knockdown of occludin with siRNA potentiated TNF‐α‐induced apoptosis, sup porting an important role of occludin integrity in endothelial cell survival. Similar results were observed for pyroptosis, in which occludin knockdown with siRNA led to a significant augmentation of cytokines secretion, inflammasome activation and pyroptosis occurrence in TNF‐α‐treated bEnd.3 cells. Lastly, upregulation of c...
Source: Journal of Neurochemistry - Category: Neuroscience Authors: Tags: ORIGINAL ARTICLE Source Type: research