부산대학교 도서관

Integrins are transmembrane receptor proteins critical for growth and stabilization of vessels, but the mechanisms by which integrin activities are involved in neoangiogenesis of the eye remain unclear. Specific inhibitors to fibronectin receptor integrin α5β1 impeded pathological neovascularization in vivo. Our objective was to determine whether α5β1 plays a role in ocular angiogenesis, and whether a novel α5β1-inhibiting small molecule is able to reduce angiogenesis in a model of inflammatory corneal neovascularization. Corneal neovascularization was induced in C57Bl/6 mice by NaOH-application and debridement of the limbal epithelium. Mice were randomized into six groups receiving either no treatment, or intraperitoneal osmotic pumps delivering three different doses of integrin antagonist or control substance on day 10 after scraping. In order to quantify the neovascular response, flatmounts were stained with FITC-CD31. Integrin α5 expression was determined by immunohistochemistry and quantified by semiquantitative western blot analysis. Influence of integrin antagonist treatment on the mRNA expression of VEGF, bFGF and integrin α5 was quantified by real-time RT–PCR. Vascularized corneas demonstrated a strong up-regulation of integrin α5 within affected areas. Animals treated systemically with α5β1-inhibiting small molecule showed a significant inhibition and regression of corneal neovascularization. PCR analysis evinced a significant up-regulation of VEGF and integrin α5 mRNA levels in injured animals compared to controls, and a significant reduction of integrin α5 mRNA in substance-treated animals compared to control substance, but no significant differences of bFGF levels in all groups. Western blot analysis of integrin α5β1 protein expression showed a trend towards up-regulation in injured animals, both control substance-treated and those treated with the α5β1-inhibiting small molecule. Systemic delivery of an α5β1-inhibiting small molecule inhibits and regresses corneal neovascularization induced by mechanical-alkali burn corneal injury. These results suggest an essential role for the integrin α5β1 in pathological neovascular processes of the cornea. Integrin α5β1 inhibitors could become a new approach for treatment of neovascularization in the eye.