Abstract
Vascular endothelial growth factor (VEGF) and inducible nitric-oxide synthase (iNOS) have been implicated in ischemia-induced retinal neovascularization. Retinal ischemia has been shown to induce VEGF and iNOS expression. It has been postulated that one of the crucial consequences of iNOS expression in the ischemic retina is the inhibition of angiogenesis. Furthermore, iNOS was shown to be overexpressed in Müller cells from patients with diabetic retinopathy. YC-1, a small molecule inhibitor of hypoxia-inducible factor (HIF)-1α, has been shown to inhibit iNOS expression in various tissue models. Our aim was to assess the pleiotropic effects of YC-1 in an oxygen-induced retinopathy (OIR) mouse model and evaluate its therapeutic potential in HIF-1- and iNOS-mediated retinal pathologies. Dual-injections of YC-1 into the neovascular retinas decreased the total retinopathy score, inhibited vaso-obliteration and pathologic tuft formation, and concomitantly promoted physiological retinal revascularization, compared with dimethyl sulfoxide (DMSO)-treated group. Furthermore, YC-1-treated retinas exhibited a marked increase in immunoreactivities for CD31 and von Willebrand factor and displayed significant inhibition in HIF-1α protein expression. Furthermore, YC-1 down-regulated VEGF, erythropoietin, endothelin-1, matrix metalloproteinase-9, and iNOS message and protein levels. When hypoxic Müller and neuoroglial cells were treated with YC-1, iNOS mRNA and protein levels were reduced in a dose-dependent fashion. We demonstrate that YC-1 inhibits pathological retinal neovascularization by exhibiting antineovascular activities, which impaired ischemia-induced expression of HIF-1 and its downstream angiogenic molecules. Furthermore, YC-1 enhanced physiological revascularization of the retinal vascular plexuses via the inhibition of iNOS mRNA and protein expressions. The pleiotropic effects of YC-1 allude to its possible use as a promising therapeutic iNOS inhibitor candidate for the treatment of retinal neovascularization.
Footnotes
↵ The online version of this article (available at http://molpharm.aspetjournals.org) contains supplemental material.
Article, publication date, and citation information can be found at http://molpharm.aspetjournals.org.
doi:10.1124/mol.109.061366
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ABBREVIATIONS:
- NV
- neovascularization
- ROP
- retinopathy of prematurity
- HIF-1
- hypoxia-inducible factor-1
- VEGF
- vascular endothelial growth factor
- iNOS
- inducible nitric-oxide synthase
- EPO
- erythropoietin
- ET-1
- endothelin-1
- OIR
- oxygen-induced retinopathy
- ROP
- retinopathy of prematurity
- P
- postnatal day
- MMP-9
- matrix metalloproteinase-9
- NOS
- nitric-oxide synthase
- sGC
- soluble guanylyl cyclase
- YC-1
- 3-(5′-hydroxymethyl-2′furyl)-1-benzyl indazole
- sGC
- soluble guanylate cyclase
- DMSO
- dimethyl sulfoxide
- FITC
- fluorescein isothiocyanate
- vWF
- von Willebrand Factor
- FBS
- fetal bovine serum
- HRP
- horseradish peroxidase
- RT-PCR
- reverse transcription-polymerase chain reaction
- PBS
- phosphate-buffered saline
- ANOVA
- analysis of variance
- FITC
- fluorescein isothiocyanate
- GCL
- ganglion cell layer
- INL
- inner nuclear layer
- IPL
- inner plexiform layer
- NFL
- nerve fibers layer
- OPL
- outer plexiform layer
- ONL
- outer nuclear layer
- OLM
- outer limiting membrane
- RGC
- retinal ganglion cell
- RV
- revascularization
- YC-1
- 3-(5′-hydroxymethyl-2′furyl)-1-benzyl indazole.
- Received September 29, 2009.
- Accepted December 14, 2009.
- Copyright © 2010 The American Society for Pharmacology and Experimental Therapeutics
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