Activation of Nrf2/ARE pathway protects endothelial cells from oxidant injury and inhibits inflammatory gene expression

1 Discovery Research, AtheroGenics, Incorporated, Alpharetta, Georgia; and 2 Department of Internal Medicine and Dorothy M. Davis Heart and Lung Research Institute, Ohio State University College of Medicine and Public Health, Columbus, Ohio Submitted 16 June 2005 ; accepted in final form 30 November 2005 The antioxidant response element (ARE) is a transcriptional control element that mediates expression of a set of antioxidant proteins. NF-E2-related factor 2 (Nrf2) is a transcription factor that activates ARE-containing genes. In endothelial cells, the ARE-mediated genes are upregulated by atheroprotective laminar flow through a Nrf2-dependent mechanism. We tested the hypothesis that activation of ARE-regulated genes via adenovirus-mediated expression of Nrf2 may suppress redox-sensitive inflammatory gene expression. Expression of Nrf2 in human aortic endothelial cells (HAECs) resulted in a marked increase in ARE-driven transcriptional activity and protected HAECs from H 2 O 2 -mediated cytotoxicity. Nrf2 suppressed TNF- -induced monocyte chemoattractant protein (MCP)-1 and VCAM-1 mRNA and protein expression in a dose-dependent manner and inhibited TNF- -induced monocytic U937 cell adhesion to HAECs. Nrf2 also inhibited IL-1 -induced MCP-1 gene expression in human mesangial cells. Expression of Nrf2 inhibited TNF- -induced activation of p38 MAP kinase. Furthermore, expression of a constitutively active form of MKK6 (an upstream kinase for p38 MAP kinase) partially reversed Nrf2-mediated inhibition of VCAM-1 expression, suggesting that p38 MAP kinase, at least in part, mediates Nrf2's anti-inflammatory action. In contrast, Nrf2 did not inhibit TNF- -induced NF- B activation. These data identify the Nrf2/ARE pathway as an endogenous atheroprotective system for antioxidant protection and suppression of redox-sensitive inflammatory genes, suggesting that targeting the Nrf2/ARE pathway may represent a novel therapeutic approach for the treatment of inflammatory diseases such as atherosclerosis. antioxidant response element; monocyte chemoattractant protein-1; vascular cell adhesion molecule-1; tumor necrosis factor- Address for reprint requests and other correspondence: X. Chen, Discovery Research, AtheroGenics, Inc., 8995 Westside Parkway, Alpharetta, GA 30004 (e-mail: xchen{at}atherogenics.com )