RhoA deletion in macrophages/microglia aggravates blood-brain barrier disruption after ischemic stroke reperfusion injury by promoting endothelial cell apoptosis and pyroptosis.

Disruption of the blood-brain barrier (BBB) is an important cause of secondary injury following cerebral ischemia-reperfusion (I/R). Database analyses revealed RhoA upregulation in macrophages/microglia within I/R brain tissue; however, the role of macrophage/microglial RhoA in BBB disruption and I/R injury remains poorly understood. In this study, we verified that macrophage/microglial RhoA was significantly upregulated in I/R mice. Employing conditional knockout (cKO) mice, present study demonstrated that the macrophage/microglial RhoA deficiency exacerbates I/R injury, manifesting as enlarged infarct volumes, aggravated cerebral oedema and BBB leakage. Mechanistically, RhoA deficiency alters the secretory profile of macrophages/microglia, enhancing pro-inflammatory factors production in macrophages/microglia, which subsequently induces pyroptosis and apoptosis while downregulates tight junction proteins in endothelial cells via the NLRP3 pathway. Collectively, our findings revealed a novel macrophage/microglial-endothelial crosstalk mechanism whereby I/R-induced RhoA upregulation in macrophages/microglia serves to attenuate their pro-inflammatory polarization, thereby preserving BBB function through suppression of NLRP3-mediated pyroptosis and apoptosis in the endothelial cells. These findings may reshape the conventional view of RhoA inhibition therapy and pave the way for more precise, cell-targeted interventions in I/R brain injury.