Oxidative stress activates endothelial innate immunity via sterol regulatory element binding protein 2 (SREBP2) transactivation of MicroRNA-92a

Background - Oxidative stress activates endothelial innate immunity and disrupts endothelial functions, including endothelial nitric oxide synthase - derived nitric oxide bioavailability. Here, we postulated that oxidative stress induces sterol regulatory element - binding protein 2 (SREBP2) and microRNA-92a (miR-92a), which in turn activate endothelial innate immune response, leading to dysfunctional endothelium. Methods and Results - Using cultured endothelial cells challenged by diverse oxidative stresses, hypercholesterolemic zebrafish, and angiotensin II - infused or aged mice, we demonstrated that SREBP2 transactivation of microRNA-92a (miR-92a) is oxidative stress inducible. The SREBP2-induced miR-92a targets key molecules in endothelial homeostasis, including sirtuin 1, Krüppel-like factor 2, and Krüppel-like factor 4, leading to NOD-like receptor family pyrin domain-containing 3 inflammasome activation and endothelial nitric oxide synthase inhibition. In endothelial cell - specific SREBP2 transgenic mice, locked nucleic acid - modified antisense miR-92a attenuates inflammasome, improves vasodilation, and ameliorates angiotensin II - induced and aging-related atherogenesis. In patients with coronary artery disease, the level of circulating miR-92a is inversely correlated with endothelial cell - dependent, flow-mediated vasodilation and is positively correlated with serum level of interleukin-1β. Conclusions - Our findings suggest that SREBP2 - miR-92a - inflammasome exacerbates endothelial dysfunction during oxidative stress. Identification of this mechanism may help in the diagnosis or treatment of disorders associated with oxidative stress, innate immune activation, and endothelial dysfunction.