title: Pro-oxidant role of heme oxygenase in mediating glucose-induced endothelial cell damage.
abstract: Oxidative damage to the vascular endothelial cells may play a crucial role in mediating glucose-induced cellular dysfunction in chronic diabetic complications. The present study was aimed at elucidating the role of glucose-induced alteration of highly inducible heme oxygenase (HO) in mediating oxidative stress in the vascular endothelial cells. We have also investigated the interaction between HO and the nitric oxide (NO) system, and its possible role in alteration of other vasoactive factors. Human umbilical vein endothelial cells (HUVECs) were exposed to low (5mmol/l) and high (25mmol/l) glucose levels. In order to determine the role of HO in endothelial dysfunction and to elucidate a possible interaction between the HO and NO systems, cells were exposed to HO inducer (hemin, 10 micromol/l), HO antagonist (SnPPIX, 10 micromol/l), and NO synthase blocker (L-NAME, 200 micromol/l) with or without NO donor (arginine, 1 mmol/l). mRNA expression of HO and NO isoforms was measured by real time RT-PCR. HO activity was measured by bilirubin production and cellular oxidative stress was assessed by 8-hydroxy-2'-deoxyguanosine (8-OHdG) and nitrotyrosine staining. We also determined the expression of vasoactive factors, endothelin-1 (ET-1) and vascular endothelial growth factor (VEGF). In the endothelial cells, glucose caused upregulation of HO-1 expression and increased HO activity. A co-stimulatory relationship between HO and NO was observed. Increased HO activity also associated with oxidative DNA and protein damage in the endothelial cells. Furthermore, increased HO activity augmented mRNA expression of vasoactive factors, ET-1 and VEGF. These data suggest that HO by itself and via elaboration of other vasoactive factors may cause endothelial injury and functional alteration. These findings are of importance in the context of chronic diabetic complications.
authors.affiliation: Department of Pathology, University of Western Ontario, London, Ontario, Canada.
authors.forename: Shali
authors.initials: S
authors.lastname: Chen
authors.forename: Zia A
authors.initials: ZA
authors.lastname: Khan
authors.forename: Yousef
authors.initials: Y
authors.lastname: Barbin
authors.forename: Subrata
authors.initials: S
authors.lastname: Chakrabarti
mesh_terms: D019332:Endothelin-1 / Q000235:genetics / Q000378:metabolism; D004730:Endothelium, Vascular / Q000187:drug effects / Q000201:enzymology*; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005947:Glucose / Q000494:pharmacology* / Q000502:physiology; D006419:Heme Oxygenase (Decyclizing) / Q000037:antagonists & inhibitors / Q000235:genetics / Q000502:physiology*; D051547:Heme Oxygenase-1; D006427:Hemin / Q000494:pharmacology; D006801:Humans; D008565:Membrane Proteins; D008665:Metalloporphyrins / Q000494:pharmacology; D009569:Nitric Oxide / Q000032:analysis / Q000378:metabolism; D019001:Nitric Oxide Synthase / Q000235:genetics / Q000378:metabolism; D052247:Nitric Oxide Synthase Type II; D016877:Oxidants / Q000502:physiology*; D018384:Oxidative Stress; D011524:Protoporphyrins / Q000494:pharmacology; D012333:RNA, Messenger / Q000032:analysis / Q000378:metabolism; D014470:Umbilical Cord / Q000166:cytology; D015854:Up-Regulation; D042461:Vascular Endothelial Growth Factor A / Q000235:genetics / Q000378:metabolism
chemical_list: D019332:Endothelin-1; D004791:Enzyme Inhibitors; D008565:Membrane Proteins; D008665:Metalloporphyrins; D016877:Oxidants; D011524:Protoporphyrins; D012333:RNA, Messenger; D042461:Vascular Endothelial Growth Factor A; D009569:Nitric Oxide; D006427:Hemin; C032628:tin protoporphyrin IX; C496319:NOS2 protein, human; D019001:Nitric Oxide Synthase; D052247:Nitric Oxide Synthase Type II; C496541:HMOX1 protein, human; D006419:Heme Oxygenase (Decyclizing); D051547:Heme Oxygenase-1; D005947:Glucose