Effects of PGC-1α on TNF-α–Induced MCP-1 and VCAM-1 Expression and NF-κB Activation in Human Aortic Smooth Muscle and Endothelial Cells

Abstract

Increased oxidative stress in vascular cells is implicated in the pathogenesis of atherosclerosis. Reactive oxygen species (ROS) induce vascular inflammation via the proinflammatory cytokine/NF-κB pathway. Several lines of evidence suggest that peroxisome proliferator-activated receptor-γ coactivator 1-α (PGC-1α) is an important regulator of intracellular ROS levels. However, no studies have examined the effects of PGC-1α on this process. We investigated the effects of PGC-1α on inflammatory molecule expression and activity of the redox-sensitive transcription factor, NF-κB, in vascular cells. PGC-1α expressed in human aortic smooth (HASMCs) and endothelial cells (HAECs) is upregulated by AMP-activated protein kinase activators, including metformin, rosiglitazone and α-lipoic acid. Tumor necrosis factor-α (TNF-α), a major proinflammatory factor in the development of vascular inflammation, stimulates intracellular ROS production through an increase in both mitochondrial ROS and NAD(P)H oxidase activity. Adenovirus-mediated overexpression of the PGC-1α gene in HASMCs and HAECs leads to a significant reduction in intracellular and mitochondrial ROS production as well as NAD(P)H oxidase activity. Consequently, NF-κB activity and MCP-1 and VCAM- 1 induced by TNF-α are suppressed. Our data support the possibility that agents stimulating PGC-1α expression in the vasculature aid in preventing the development of atherosclerosis.