Li Lixin, Frei Balz
Linus Pauling Institute, Oregon State University, Corvallis, OR 97331-6512, USA.
Arterioscler Thromb Vasc Biol. 2009 May;29(5):732-8. doi: 10.1161/ATVBAHA.108.183210. Epub 2009 Feb 26.
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).
Incubation of HAECs for 24 hours with 5 microg/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 micromol/L DFO. Incubating HAECs with LPS also significantly increased cellular iron and heme levels and mRNA and protein levels of p22phox, 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 micromol/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 p47phox 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.
Our data indicate that prolonged exposure to LPS or iron increases endothelial NADPH oxidase activity by increasing p22phox gene transcription and cellular levels of iron, heme, and p22phox protein. Iron chelation by DFO effectively suppresses endothelial NADPH oxidase activity, which may be helpful as an adjunct in reducing vascular oxidative stress and inflammation in atherosclerosis.
血管氧化应激和炎症是动脉粥样硬化的促成因素。我们最近发现，铁螯合剂去铁胺（DFO）可抑制脂多糖（LPS）处理的小鼠中NADPH氧化酶介导的氧化应激和细胞黏附分子的表达。本研究的目的是调查LPS和铁是否以及如何增强，以及DFO如何抑制人主动脉内皮细胞（HAECs）中的NADPH氧化酶活性。
用5μg/mL LPS孵育HAECs 24小时导致NADPH氧化酶活性增加4倍，而用100μmol/L DFO预处理细胞24小时可强烈抑制该活性。用LPS孵育HAECs也显著增加了细胞铁和血红素水平以及p22phox（NADPH氧化酶的含血红素催化亚基）的mRNA和蛋白质水平。LPS对HAECs的所有这些作用均被DFO强烈抑制。将HAECs暴露于100μmol/L铁（柠檬酸铁）48小时产生了与LPS相似的作用，并且这些作用在与DFO共同孵育时被强烈抑制。此外，LPS和DFO均不影响NADPH氧化酶的不含血红素的调节亚基p47phox的mRNA和蛋白质水平，也不影响内皮细胞中NADPH氧化酶主要催化亚基的同种型NOX4的mRNA水平。相反，无论是否存在LPS或铁，血红素加氧酶-1均被DFO强烈抑制。
我们的数据表明，长时间暴露于LPS或铁会通过增加p22phox基因转录以及细胞铁、血红素和p22phox蛋白水平来增加内皮NADPH氧化酶活性。DFO进行铁螯合可有效抑制内皮NADPH氧化酶活性，这可能有助于作为辅助手段减轻动脉粥样硬化中的血管氧化应激和炎症。
