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

Abstract

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 H2O2-mediated cytotoxicity. Nrf2 suppressed TNF-α-induced monocyte chemoattractant protein (MCP)-1 and VCAM-1 mRNA and protein expression in a dose-dependent manner and inhibited TNF-α-induced monocytic U937 cell adhesion to HAECs. Nrf2 also inhibited IL-1β-induced MCP-1 gene expression in human mesangial cells. Expression of Nrf2 inhibited TNF-α-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-α-induced NF-κB 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.

Coordinate regulation of enzyme markers for inflammation and for protection against oxidants and electrophiles

“…Moreover, nrf2 knockout mice showed prolonged inflammation during cutaneous wound healing (31) and displayed enhanced bronchial inflammation and susceptibility to severe airway inflammation and asthma (32,33). The Keap1/Nrf2/ARE pathway has also been shown to modulate redox-sensitive inflammatory gene expression in endothelial cells (34). Also in Nrf2-deficient mouse embryonic fibroblasts exposed to both inflammatory cytokines INF-␥ and TNF-␣, we observed that the Keap1/Nrf2/ARE pathway is essential for the anti-inflammatory effects of triterpenoids (19).…”

The C609T variant of NQO1 is associated with carotid artery plaques in patients with type 2 diabetes

“…Oxidative stress induces NQO1 expression as a defense system [14]. Endogenous antioxidant systems have been shown to suppress the expression of redox-sensitive inflammatory genes such as monocyte chemoattractant proteins (MCP)-1 and vascular cell adhesion molecules (VCAM)-1 [7,15]. In addition, the atheroprotective properties of laminar shear stress are mediated through NQO1 expression, and thus NQO1 appears to be important in protecting vessels against oxidative stress and atherogenesis [4,7,15].…”

Oxidative stress-inducible lentiviral vectors for gene therapy

“…10,27,28 AREregulated gene transcription has been shown to be a central mechanism providing protection against oxidative stress in the cardiovascular system. [29][30][31] Oxidized low density lipoprotein and 15d-PGJ 2 , agents that are important in vascular inflammatory processes such as atherogenesis and are present in atherosclerotic lesions, 22,32 are also potent instigators of ARE activation, 17,33 suggesting that vascular inflammatory processes could be targets for ARE-regulated gene therapy. In addition, in I/R injury, activation of Nrf2 during reperfusion mediates cytoprotective gene expression, 34 implying that ARE-regulated vectors could also be used for attenuation of reperfusion injury.…”