Targeting Oxidative Stress Attenuates Vascular Fibrosis in Cellular and Animal Models of Hyperlipidemia

Hyperlipidemia-associated atherosclerosis promotes plaque formation and extracellular matrix accumulation in the vascular media, increasing also the production of reactive oxygen species (ROS), inflammation, and the oxidation of LDL to oxidized-LDL, through mechanisms that remain unknown. Our objective was to determine whether oxidizedLDL-induced oxidative stress drives fibrosis in the arterial media during atherosclerosis and whether antioxidants can prevent or reduce this effect. Experiments were conducted in vascular smooth muscle cells (VSMCs) and in apolipoproteinE-knockout (KO-apoE) mice. ROS production was measured by confocal microscopy and fibrosis by immunofluorescence, Western and RT-qPCR in VSMCs and by Sirius red staining and RT-qPCR in mice. In VSMCs, oxidized-LDL treatment significantly increased the expression of TGF-beta, fibronectin and collagen-I, indicating fibrosis. Additionally, oxidized-LDL enhanced ROS production and NF-κB activation. The fibrotic response was prevented by treatment with the antioxidant N-acetylcysteine (NAC) and an NF-κB inhibitor, suggesting that the ROS-NF-κB axis mediates these effects in VSMCs. In vivo, KO-apoE mice exhibited higher cholesterol levels and increased ROS production compared with wild-type controls. These mice also showed enhanced aortic fibrosis. Importantly, NAC administration reduced both ROS production and fibrosis in KO-apoE mice. Overall, the findings suggest that both oxidized-LDL-induced vascular fibrosis and hyperlipidemia-induced fibrosis are mediated by ROS.