Induction of heme oxygenase-1 in vivo suppresses NADPH oxidase derived oxidative stress

Hypertension. 2007 Oct;50(4):636-42. doi: 10.1161/HYPERTENSIONAHA.107.092296. Epub 2007 Aug 6.


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.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Angiotensin II / physiology
  • Animals
  • Apolipoproteins E / genetics
  • Apolipoproteins E / metabolism
  • Bilirubin / pharmacology
  • Cell Line
  • Enzyme Induction
  • Enzyme Inhibitors / pharmacology
  • F2-Isoprostanes / blood
  • HL-60 Cells
  • Heme Oxygenase-1 / antagonists & inhibitors
  • Heme Oxygenase-1 / drug effects*
  • Heme Oxygenase-1 / metabolism*
  • Hemin / pharmacology*
  • Humans
  • Male
  • Metalloporphyrins / pharmacology
  • Mice
  • Mice, Mutant Strains
  • Muscle, Smooth, Vascular / cytology
  • Muscle, Smooth, Vascular / enzymology
  • NADPH Oxidases / antagonists & inhibitors
  • NADPH Oxidases / metabolism*
  • Nitrates / metabolism
  • Nitrites / metabolism
  • Oxidative Stress / drug effects
  • Oxidative Stress / physiology*
  • Phagocytes / cytology
  • Phagocytes / enzymology
  • Protoporphyrins / pharmacology
  • Rats
  • Superoxides / metabolism


  • Apolipoproteins E
  • Enzyme Inhibitors
  • F2-Isoprostanes
  • Metalloporphyrins
  • Nitrates
  • Nitrites
  • Protoporphyrins
  • Superoxides
  • Angiotensin II
  • tin protoporphyrin IX
  • Hemin
  • Heme Oxygenase-1
  • NADPH Oxidases
  • Bilirubin