Induction of Caspase-Mediated Cell Death by Matrix Metalloproteinases in Cerebral Endothelial Cells after Hypoxia—Reoxygenation

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Abstract
Matrix metalloproteinases (MMPs) may contribute to the pathophysiology of cerebral ischemia by degrading matrix components in the neurovascular unit. In this study, the authors document a pathway by which MMPs interfere with cell—matrix interactions and trigger caspase-mediated cytotoxicity in brain endothelial cells. Hypoxia—reoxygenation induced endothelial cytotoxicity. Cytoprotection with zDEVD-fmk confirmed that cell death was partly caspase mediated. The temporal profile of caspase-3 activation was matched by elevations in MMP-2 and MMP-9. MMP inhibitors significantly decreased caspase-3 activation and reduced endothelial cell death. Degradation of matrix fibronectin confirmed the presence of extracellular proteolysis. Increasing integrin-linked kinase signaling with the β1 integrin-activating antibody (8A2) ameliorated endothelial cytotoxicity. The results suggest that MMP-9 and MMP-2 contribute to caspase-mediated brain endothelial cell death after hypoxia—reoxygenation by disrupting cell—matrix interactions and homeostatic integrin signaling.