NDUFC2 deficiency exacerbates endothelial mesenchymal transformation during ischemia-reperfusion via NLRP3

Ischemic stroke is the main type of cerebrovascular disease. Emergency thrombectomy combined with medication therapy is currently the primary treatment for stroke. Inflammation and oxidative stress induced by ischemia-reperfusion cause secondary damage to blood vessels, especially endothelial mesenchymal transformation (EndoMT). However, much is still unclear about the role of EndoMT in ischemia-reperfusion. In this study, an in vivo ischemia-reperfusion model was established by transient middle cerebral artery occlusion (tMCAO) in wild-type (WT) C57BL/6 mice and NLRP3 (NOD-like receptor thermal protein domain associated protein 3) knockout (KO) C57BL/6 mice. An in vitro ischemia-reperfusion model was established by oxygen glucose deprivation and reoxygenation (OGD/R) of human brain microvascular endothelial cells (HBMECs). α-SMA (alpha smooth muscle actin), CD31 (platelet endothelial cell adhesion molecule-1, PECAM-1/CD31), NDUFC2 (NADH: ubiquinone oxidoreductase subunit C2), and NLRP3 were used to evaluate EndoMT and inflammation. Real-time PCR measured superoxide dismutase 1 (SOD1) and catalase (CAT) mRNA expression to evaluate oxidative stress levels. NLRP3 was activated by ischemia-reperfusion injury and NLRP3 inactivation inhibited the EndoMT in tMCAO mice. Further experiments demonstrated that OGD/R treatment induced NLRP3 activation and EndoMT in HBMECs, which resulted in NDUFC2 deficiency. NDUFC2 overexpression suppressed NLRP3 activation and EndoMT in HBMECs induced by OGD/R. Moreover, NDUFC2 overexpression rescued SOD1 and CAT mRNA expression. These results demonstrated that NDUFC2 deficiency decreased the antioxidant levels, leading to NLRP3 activation and EndoMT during ischemia-reperfusion injury and suggesting that NDUFC2 is a potential drug target for the treatment of ischemic stroke.