Prolonged Exposure to LPS Increases Iron, Heme, and p22 ^phox Levels and NADPH Oxidase Activity in Human Aortic Endothelial Cells

Abstract

Objective-Vascular oxidative stress and inflammation are contributing factors in atherosclerosis. We recently found that the iron chelator, desferrioxamine (DFO), suppresses NADPH oxidase-mediated oxidative stress and expression of cellular adhesion molecules in mice treated with lipopolysaccharide (LPS). The objective of the present study was to investigate whether and how LPS and iron enhance, and DFO inhibits, NADPH oxidase activity in human aortic endothelial cells (HAECs). Methods and Results-Incubation of HAECs for 24 hours with 5 g/mL LPS led to a 4-fold increase in NADPH oxidase activity, which was strongly suppressed by pretreatment of the cells for 24 hours with 100 mol/L DFO. Incubating HAECs with LPS also significantly increased cellular iron and heme levels and mRNA and protein levels of p22 phox , a heme-containing, catalytic subunit of NADPH oxidase. All of these effects of LPS on HAECs were strongly inhibited by DFO. Exposing HAECs to 100 mol/L iron (ferric citrate) for 48 hours exerted similar effects as LPS, and these effects were strongly inhibited by coincubation with DFO. Furthermore, neither LPS nor DFO affected mRNA and protein levels of p47 phox a nonheme-containing, regulatory subunit of NADPH oxidase, or the mRNA level of NOX4, an isoform of the principal catalytic subunit of NADPH oxidase in endothelial cells. In contrast, heme oxygenase-1 was strongly suppressed by DFO, both in the absence and presence of LPS or iron. Conclusions-Our

Iron reduction by deferoxamine leads to amelioration of adiposity via the regulation of oxidative stress and inflammation in obese and type 2 diabetes KKAy mice

“…We found that NADPH oxidase activity as well as the level of p22 phox , a subunit of the NADPH component, was decreased in adipose tissue by DFO treatment. Consistent with our observation, Li and Frei reported that DFO treatment suppressed lipopolysaccharide-induced NADPH oxidase activity via attenuation of p22 phox protein expression in vivo (27) and in vitro (28). Elemental iron is necessary for enzyme activity of NADPH oxidase (33) as well as the biosynthesis of heme proteins, including the p22 phox subunit (43).…”

Iron Sucrose Accelerates Early Atherogenesis by Increasing Superoxide Production and Upregulating Adhesion Molecules in CKD

“…intravenous iron preparations inhibited proliferation and promoted apoptosis of cultured endothelial cells 24,25 as well as increased MNC-endothelial adhesion in vitro 6,26 ; however, a reliable cell model for atherogenesis [27][28][29] and the exact signaling pathway have not been fully established. Li and Frei 30 have found that iron increased endothelial NOx activity and ROS production in cultured endothelial cells. Additionally, ROS is thought to induce endothelial damage through activation of NF-kB, a major redox-sensitive transcription factor that is a key regulator of cytokines, chemokines, and cellular adhesion molecules.…”

Dietary iron restriction inhibits progression of diabetic nephropathy indb/dbmice

“…In the relationship between NADPH oxidase and iron, the p22 phox subunit is identified as an important target of the antioxidant effect of iron reduction. Li and Frei (33,34) have shown that LPS or iron-induced increase of p22 phox protein and NADPH oxidase activity was suppressed by deferoxamine (DFO), an iron chelator, in mice and endothelial cells. We previously found that DFO prevented white adipocyte hypertrophy through the suppression of oxidative stress via reducing p22 phox protein expression and NADPH oxidase activity.…”