Induction of heme oxygenase-1 in vivo suppresses NADPH oxidase derived oxidative stress.
Our previous studies suggest that heme oxygenase (HO)-1 induction and/or subsequent bilirubin generation in endothelial cells may suppress superoxide generation of from reduced nicotinamide-adenine dinucleotide phosphate (NADPH) oxidase. In this study, we examined the consequence of HO-1 induction in vivo on NADPH oxidase activity. Three doses of hemin (25 mg x kg(-1), IP, every 48 hours), with or without cotreatment with the HO inhibitor tin protoporphyrin-IX (15 mg x kg(-1), IP), were given to apolipoprotein E-deficient mice, which display vascular oxidative stress. Hemin treatment increased HO-1 expression and activity in aorta (undetectable at baseline) and kidney (by 3-fold) and significantly reduced both NADPH oxidase activity (by approximately 25% to 50%) and superoxide generation in situ. The increase in HO-1 activity and inhibition of NADPH oxidase activity by hemin were reversed by tin protoporphyrin-IX and were not associated with changes in Nox2 or Nox4 protein levels. Hemin also reduced plasma F(2)-isoprostane levels by 23%. The inhibition of NADPH oxidase activity by hemin in the aorta was mimicked by bilirubin in vitro (0.01 to 1 micromol/L). Bilirubin also concentration-dependently reduced NADPH oxidase-dependent superoxide production stimulated by angiotensin II in rat vascular smooth muscle cells and by phorbol 12-myristate 13-acetate in human neutrophil-like HL-60 cells. HO-1 overexpression by plasmid-mediated gene transfer in rat vascular smooth muscle cells decreased NADPH-stimulated superoxide production. Thus, systemic expression of HO-1 suppresses NADPH oxidase activity by mechanisms at least partly mediated by the bile pigment bilirubin, thereby reducing oxidative stress.
Bernard O'Brien Institute of Microsurgery, University of Melbourne, Victoria, Australia.
Srinivasa R
SR
Datla
Gregory J
GJ
Dusting
Trevor A
TA
Mori
Caroline J
CJ
Taylor
Kevin D
KD
Croft
Fan
F
Jiang
D000804:Angiotensin II / Q000502:physiology; D000818:Animals; D001057:Apolipoproteins E / Q000235:genetics / Q000378:metabolism; D001663:Bilirubin / Q000494:pharmacology; D002460:Cell Line; D004790:Enzyme Induction; D004791:Enzyme Inhibitors / Q000494:pharmacology; D028441:F2-Isoprostanes / Q000097:blood; D018922:HL-60 Cells; D051547:Heme Oxygenase-1 / Q000037:antagonists & inhibitors / Q000187:drug effects* / Q000378:metabolism*; D006427:Hemin / Q000494:pharmacology*; D006801:Humans; D008297:Male; D008665:Metalloporphyrins / Q000494:pharmacology; D051379:Mice; D008817:Mice, Mutant Strains; D009131:Muscle, Smooth, Vascular / Q000166:cytology / Q000201:enzymology; D019255:NADPH Oxidases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D009566:Nitrates / Q000378:metabolism; D009573:Nitrites / Q000378:metabolism; D018384:Oxidative Stress / Q000187:drug effects / Q000502:physiology*; D010586:Phagocytes / Q000166:cytology / Q000201:enzymology; D011524:Protoporphyrins / Q000494:pharmacology; D051381:Rats; D013481:Superoxides / Q000378:metabolism
D001057:Apolipoproteins E; D004791:Enzyme Inhibitors; D028441:F2-Isoprostanes; D008665:Metalloporphyrins; D009566:Nitrates; D009573:Nitrites; D011524:Protoporphyrins; D013481:Superoxides; D000804:Angiotensin II; D006427:Hemin; C032628:tin protoporphyrin IX; D051547:Heme Oxygenase-1; D019255:NADPH Oxidases; D001663:Bilirubin