Neutrophils are mobilized to the vascular wall during vessel inflammation. Published data are conflicting on phagocytic nicotinamide-adenine dinucleotide phosphate (NADPH) oxidase activation during the hypertensive state, and the capacity of angiotensin II (Ang II) to modulate the intracellular redox status has not been analyzed in neutrophils. We here describe that Ang II highly stimulates endogenous and extracellular O 2 ؊ production in these cells, consistent with the translocation to the cell membrane of the cytosolic components of NADPH oxidase, p47 phox , and p67 phox . The Ang II-dependent O 2 ؊ production was suppressed by specific inhibitors of AT1 receptors, of the p38MAPK and ERK1/2 pathways, and of flavin oxidases. Furthermore, Ang II induced a robust phosphorylation of p38MAPK, ERK1/2, and JNK1/2 (particularly JNK2), which was hindered by inhibitors of NADPH oxidase, tyrosine kinases, and ROS scavengers. Ang II increased cytosolic Ca 2؉ levels-released mainly from calcium stores-enhanced the syn- IntroductionAngiotensin II (Ang II), the main peptide hormone of the reninangiotensin system, induces leukocyte recruitment to the vessel wall, which constitutes a hallmark of the early stages of atherosclerosis and several hypertensive diseases. 1 In addition, it plays a regulatory role on blood pressure and circulation volume and on the proliferation of vascular smooth muscle cells. 2 Ang II acts through high-affinity cell surface receptors (AT1), which are linked to pathways classically associated with G-protein-coupled and tyrosine-kinase-mediated responses. 3 Although most studies on Ang II have been carried out in smooth muscle and endothelial cells, experimental evidence has been obtained on its effects on circulating cells. AT1 receptors for Ang II have been found recently in circulating neutrophils 4 and human peripheral monocytes, 5 and Ang II-induced cell activation in the latter has been reported. 6 In this context, the migration of leukocytes from blood to sites of inflammation and their adhesion to endothelial cells are primary events taking place during the acute inflammatory response and the pathogenesis of vascular diseases. 7 Because chronic inflammation of vessel walls is a hallmark of atherosclerosis, 8 and reactive oxygen species (ROS) such as superoxide anion (O 2 Ϫ ) and H 2 O 2 constitute the main intermediary molecules responsible for inflammation, 9 a link between atherosclerosis and ROS production has been postulated. 10 Nicotinamideadenine dinucleotide phosphate (NADPH) oxidase of phagocytes catalyzes the reduction of oxygen to O 2 Ϫ . In resting cells this enzyme is inactive, and its components are distributed between the cytosol and the membrane of secretory vesicles. When phagocytic cells are activated, the enzyme's cytosolic components associate to membrane-bound components and assemble into catalytically active NADPH oxidase. 11 It has been reported that Ang II-induced hypertrophy of vascular smooth muscle cells is mediated by both O 2 Ϫ and H 2 O 2 . 12 In addition, ROS ha...

Interleukin (IL)-1β is a pleiotropic cytokine implicated in a variety of activities, including damage of insulin-producing cells, brain injury, or neuromodulatory responses. Many of these effects are mediated by nitric oxide (NO) produced by the induction of NO synthase (iNOS) expression. We report here that IL-1β provokes a marked repression of genes, such as fragile X mental retardation 1 (FMR1) and hypoxanthine phosphoribosyltransferase (HPRT), having a CpG island in their promoter region. This effect can be fully prevented by iNOS inhibitors and is dependent on DNA methylation. NO donors also cause FMR1 and HPRT gene silencing. NO-induced methylation of FMR1 CpG island can be reverted by demethylating agents which, in turn, produce the recovery of gene expression. The effects of IL-1β and NO appear to be exerted through activation of DNA methyltransferase (DNA MeTase). Although exposure of the cells to NO does not increase DNA MeTase gene expression, the activity of the enzyme selectively increases when NO is applied directly on a nuclear protein extract. These findings reveal a previously unknown effect of IL-1β and NO on gene expression, and demonstrate a novel pathway for gene silencing based on activation of DNA MeTase by NO and acute modification of CpG island methylation.