Background-Reactive oxygen species (ROS) play a major role in vascular inflammation and pathophysiology of many vascular diseases such as atherosclerosis and injury-induced neointima formation after balloon angioplasty. Nuclear factor E2-related factor-2 (Nrf2) is a transcription factor orchestrating antioxidant and cytoprotective responses on oxidative and electrophilic stress, and it has been shown to have antiinflammatory effects in vascular cells in vitro. We therefore postulated that Nrf2 gene transfer would have salutary effects on vascular inflammation after angioplasty. Methods and Results-Transduction of vascular smooth muscle cells (VSMCs) with Nrf2-expressing adenovirus increased the expression of several antioxidant enzymes including heme oxygenase-1 (HO-1) compared with ␤-galactosidase (AdLacZ)-transduced controls. Moreover, Nrf2 gene transfer also inhibited vascular smooth muscle cell (VSMC) proliferation, and the effect was partially reversed by the HO inhibitor Sn(IV) protoporphyrin. In vivo, adenoviral gene transfer effectively reduced oxidative stress determined by antibody staining against oxidized epitopes of LDL, as well as inhibited vascular inflammation assessed by the macrophage cell count and monocyte chemoattractant protein-1 (MCP-1) staining. However, the antiproliferative effects of Nrf2 in vivo were counterbalanced with diminished apoptosis in neointimal VSMCs, resulting in no change in neointimal hyperplasia. Conclusions-Nrf2

Besides their well-characterized proinflammatory and proatherogenic effects, oxidized phospholipids, such as oxPAPC (oxidized 1-palmitoyl-2-arachidonoyl-sn-glycero-phosphocholine) have been shown to have beneficial responses in vascular cells via induction of antioxidant enzymes such as heme oxygenase-1. We therefore hypothesized that oxPAPC could evoke a general cytoprotective response via activation of antioxidative transcription factor Nrf2. Here, we show that oxPAPC increases nuclear accumulation of Nrf2. Using the small interfering RNA approach, we demonstrate that Nrf2 is critical in mediating the induction of glutamate-cysteine ligase modifier subunit (GCLM) and NAD(P)H quinone oxidoreductase-1 (NQO1) by oxPAPC in human endothelial cells, whereas the contribution to the induction of heme oxygenase-1 was less significant. The induction of GCLM and NQO1 was attenuated by reduction of electrophilic groups with sodium borohydrate, as well as treatment with thiol antioxidant N-acetylcysteine, suggesting that the thiol reactivity of oxPAPC is largely mediating its effect on Nrf2-responsive genes. Moreover, we show that oxidized phospholipid having a highly electrophilic isoprostane ring in its sn-2 position is a potent inducer of Nrf2 target genes. Finally, we demonstrate that the oxPAPC-inducible expression of heme oxygenase-1, GCLM, and NQO1 is lower in Nrf2-null than wild-type mouse carotid arteries in vivo. We suggest that the activation of Nrf2 by oxidized phospholipids provides a mechanism by which their deleterious effects are limited in the vasculature.

Nrf2 deficiency specific to bone marrow-derived cells aggravates atherosclerosis in LDLR(-/-) mice. Furthermore, the loss of Nrf2 in macrophages enhances foam cell formation and promotes the pro-inflammatory phenotype.

The results suggest a central pathogenetic role of oxidation sensitive signaling processes in endothelial recovery and developing in-stent restenosis in atherosclerotic vessels. Local therapy against oxidative stress represents a promising therapeutic strategy in stent-induced vascular injury.