Abstract: Microglia, which are the resident macrophages of the central nervous system, are an important part of the inflammatory response that occurs after cerebral ischemia. Vav guanine nucleotide exchange factor 1 (Vav1) is a guanine nucleotide exchange factor that is related to microglial activation. However, how Vav1 participates in the inflammatory response after cerebral ischemia/reperfusion injury remains unclear. In this study, we subjected rats to occlusion and reperfusion of the middle cerebral artery and subjected the BV-2 microglia cell line to oxygen-glucose deprivation/reoxygenation to mimic cerebral ischemia/reperfusion in vivo and in vitro, respectively. We found that Vav1 levels were increased in the brain tissue of rats subjected to occlusion and reperfusion of the middle cerebral artery and in BV-2 cells subjected to oxygen-glucose deprivation/reoxygenation. Silencing Vav1 reduced the cerebral infarct volume and brain water content, inhibited neuronal loss and apoptosis in the ischemic penumbra, and improved neurological function in rats subjected to occlusion and reperfusion of the middle cerebral artery. Further analysis showed that Vav1 was almost exclusively localized to microglia and that Vav1 downregulation inhibited microglial activation and the NOD-like receptor pyrin 3 (NLRP3) inflammasome in the ischemic penumbra, as well as the expression of inflammatory factors. In addition, Vav1 knockdown decreased the inflammatory response exhibited by BV-2 cells after oxygen-glucose deprivation/reoxygenation. Taken together, these findings show that silencing Vav1 attenuates inflammation and neuronal apoptosis in rats subjected to cerebral ischemia/reperfusion through inhibiting the activation of microglia and NLRP3 inflammasome.

Key words: apoptosis, cerebral ischemia/reperfusion, inflammatory cytokines, microglia, microglial activation, middle cerebral artery occlusion, neuroprotection, NLRP3 inflammasome, oxygen-glucose deprivation/reoxygenation, Vav1