Muzaffar Saima, Shukla Nilima, Angelini Gianni D, Jeremy Jamie Y
Bristol Heart Institute, University of Bristol, Bristol, UK.
Eur J Pharmacol. 2006 May 24;538(1-3):108-14. doi: 10.1016/j.ejphar.2006.03.047. Epub 2006 Mar 28.
Central to the aetiology of Acute Respiratory Distress Syndrome (ARDS) is superoxide, the principal source of which is nicotinamide adenine dinucleotide phosphate oxidase (NADPH oxidase). To test whether superoxide may influence NADPH oxidase expression directly, the effect of incubation of superoxide with porcine pulmonary arterial endothelial cells on the expression of gp91(phox) (a catalytic subunit of NADPH oxidase) and superoxide formation was investigated. Since iloprost has been purported to be potentially effective in treating ARDS, the effect of iloprost on superoxide-mediated effects was also studied. Pulmonary artery endothelial cells were incubated with xanthine/xanthine oxidase which generates superoxide, or tumour necrosis factor alpha (TNFalpha) or thromboxane A(2) analogue, U46619 (+/- superoxide dismutase [SOD] or catalase or iloprost) for 16 h. Cells were then washed and superoxide formation assessed spectrophometrically and gp91(phox) expression using Western blotting. The role of NADPH oxidase was also studied in the above settings using apocynin, an NADPH oxidase inhibitor. Superoxide, TNFalpha and U46619 elicited an increase in the formation of superoxide and induced gp91(phox) expression in pulmonary artery endothelial cells following a 16 h incubation an effect blocked by the continual presence of SOD and apocynin but not catalase. Apocynin completely inhibited superoxide formation induced with xanthine/xanthine oxidase after the 16 h incubation. Rotenone and allopurinol were without effect. Iloprost inhibited the formation of superoxide and gp91(phox) expression. These data demonstrate that superoxide upregulates gp91(phox) expression in pulmonary artery endothelial cells and thus augments superoxide formation, an effect blocked by iloprost. This constitutes a novel mechanism by which vascular superoxide creates a self-perpetuating cascade that may be of importance to the etiology of ARDS and other vasculopathies.
急性呼吸窘迫综合征（ARDS）病因的核心是超氧化物，其主要来源是烟酰胺腺嘌呤二核苷酸磷酸氧化酶（NADPH氧化酶）。为了测试超氧化物是否可能直接影响NADPH氧化酶的表达，研究了超氧化物与猪肺动脉内皮细胞孵育对gp91（phox）（NADPH氧化酶的催化亚基）表达和超氧化物形成的影响。由于伊洛前列素据称对治疗ARDS可能有效，因此也研究了伊洛前列素对超氧化物介导作用的影响。将肺动脉内皮细胞与产生超氧化物的黄嘌呤/黄嘌呤氧化酶、肿瘤坏死因子α（TNFα）或血栓素A2类似物U46619（±超氧化物歧化酶[SOD]或过氧化氢酶或伊洛前列素）孵育16小时。然后洗涤细胞，用分光光度法评估超氧化物形成，并使用蛋白质印迹法检测gp91（phox）表达。在上述实验条件下，还使用NADPH氧化酶抑制剂阿朴吗啡研究了NADPH氧化酶的作用。超氧化物、TNFα和U46619在孵育16小时后引起肺动脉内皮细胞中超氧化物形成增加并诱导gp91（phox）表达，这一效应被持续存在的SOD和阿朴吗啡阻断，但未被过氧化氢酶阻断。孵育16小时后，阿朴吗啡完全抑制了黄嘌呤/黄嘌呤氧化酶诱导的超氧化物形成。鱼藤酮和别嘌呤醇无作用。伊洛前列素抑制超氧化物形成和gp91（phox）表达。这些数据表明，超氧化物上调肺动脉内皮细胞中gp91（phox）的表达，从而增强超氧化物形成，这一效应被伊洛前列素阻断。这构成了一种新机制，通过该机制血管超氧化物产生一个自我延续的级联反应可能对ARDS和其他血管病变的病因学具有重要意义。
