Inhibition of NAD(P)H oxidase activity blocks vascular endothelial growth factor overexpression and neovascularization during ischemic retinopathy

Mohamed Al-Shabrawey, Manuela Bartoli, Azza B. El-Remessy, Daniel H. Platt, Sue Matragoon, M. Ali Behzadian, Robert W. Caldwell, Ruth B. Caldwell

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Abstract

Because oxidative stress has been strongly implicated in up-regulation of vascular endothelial growth factor (VEGF) expression in ischemic retinopathy, we evaluated the role of NAD(P)H oxidase in causing VEGF overexpression and retinal neovascularization. Dihydroethidium imaging analyses showed increased superoxide formation in areas of retinal neovascularization associated with relative retinal hypoxia in a mouse model for oxygen-induced retinopathy. The effect of hypoxia in stimulating superoxide formation in retinal vascular endothelial cells was confirmed by in vitro chemiluminescence assays. The superoxide formation was blocked by specific inhibitors of NAD(P)H oxidase activity (apocynin, gp91ds-tat) indicating that NAD(P)H oxidase is a major source of superoxide formation. Western blot and immunolocalization analyses showed that retinal ischemia increased expression of the NAD(P)H oxidase catalytic subunit gp91phox, which localized primarily within vascular endothelial cells. Treatment of mice with apocynin blocked ischemia-induced increases in oxidative stress, normalized VEGF expression, and prevented retinal neovascularization. Apocynin and gp91ds-tat also blocked the action of hypoxia in causing increased VEGF expression in vitro, confirming the specific role of NAD(P)H oxidase in hypoxia-induced increases in VEGF expression. In conclusion, NAD(P)H oxidase activity is required for hypoxia-stimulated increases in VEGF expression and retinal neovascularization. Inhibition of NAD(P)H oxidase offers a new therapeutic target for the treatment of retinopathy.

Original languageEnglish (US)
Pages (from-to)599-607
Number of pages9
JournalAmerican Journal of Pathology
Volume167
Issue number2
DOIs
StatePublished - Aug 2005

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NADPH Oxidase
Vascular Endothelial Growth Factor A
Retinal Neovascularization
Superoxides
Oxidative Stress
Ischemia
Endothelial Cells
Retinal Vessels
Luminescence
Catalytic Domain
Up-Regulation
Western Blotting
Hypoxia
Oxygen
acetovanillone

ASJC Scopus subject areas

  • Pathology and Forensic Medicine

Cite this

Inhibition of NAD(P)H oxidase activity blocks vascular endothelial growth factor overexpression and neovascularization during ischemic retinopathy. / Al-Shabrawey, Mohamed; Bartoli, Manuela; El-Remessy, Azza B.; Platt, Daniel H.; Matragoon, Sue; Behzadian, M. Ali; Caldwell, Robert W.; Caldwell, Ruth B.

In: American Journal of Pathology, Vol. 167, No. 2, 08.2005, p. 599-607.

Research output: Contribution to journalArticle

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