Inhibition of NOX4 prevents the development of atherosclerosis in Ldlr-/- mice

Atherosclerosis is a progressive disease with endothelial cell inflammation. Recent studies showed that oxidative stress is an important factor in inducing endothelial cell inflammation. NOX4 is a major ROS-producing enzyme in endothelial cells, yet its role in the pathogenesis of atherosclerosis and plaque formation remains unclear. LDLr-/- mice were fed with high fat diet for 16 weeks to establish atherosclerosis model and treated with NOX4 siRNA. NOX4 expression was detected by western blot. H2O2 level was determined by the kit. Plaque formation was assessed by general oil red O staining and HE staining. Aorta endothelial cells were treated with oxLDL to mimic the atherosclerosis after transfected with NOX4 siRNA. ROS level and cell apoptosis were evaluated by flow cytometry and AV-PI staining. NOX4 expression was significantly increased in atherosclerotic mice with huge amount of tissue H2O2 production (P < 0.01). NOX4 siRNA obviously reduced the production of tissue H909 (P < 0.01), decreased atherosclerotic plaque area, and elevated endothelial integrity. In endothelial cells, NOX4 increased markedly in model group compared with normal control (P < 0.01), accompanied with massive production of ROS. Inhibition of NOX4 expression reduced ROS production and inhibited apoptosis (P < 0.01). In conclusion, a large amount of ROS produced by NOX4 is the initiating factor of atherosclerosis and inhibition of NOX4 level shows a protective effect on atherosclerosis, suggesting that NOX4 may serve as a key target for the treatment of atherosclerosis.