Integrin Alpha5beta1–Inhibiting Small Molecule Reduces Corneal Neovascularisation

Abstract

Abstract: : Purpose: Neovascularisation in diverse tissues of the eye is a major cause for deterioration and loss of vision. In former literature studies α5ß1 specific inhibitors inhibited pathological neovascularisation in tumor models and chicken chorioallantoic membrane model (CAM). Our objective is to determine whether alpha5beta1–inhibiting small molecule reduces and regresses corneal neovascularisation in induced mechanical–chemical limbal insufficiency. Methods: Corneal neovascularisation in C57 mice was induced by NaOH–application and limbal scraping. Mice were randomised to three groups receiving either no treatment, or intraperitoneal osmotic pumps delivering anti–integrin or vehicle. Corneae were harvested two weeks after injury, or one week after treatment, respectively. Flatmounts were stained with FITC–CD31 and Cy3–SMA. In a second setup, after equal injury, staining with anti–integrin alpha5 was performed to detect the expression of integrin alpha5beta1. Influence of anti–integrin treatment on VEGF and AGPT1+2 expression was quantified by RT–PCR. Results: Animals with systemic treatment of alpha5beta1–inhibiting small molecule showed a significant inhibition of corneal neovascularisation following induced limbal injury compared to controls, analysed via neovascularisation area percentage. Compared to non–injured, avascular corneae, by immunostaining, injured objects showed a strong upregulation of integrin alpha5–beta1in the affected areas. PCR analysis showed a significant reduction of VEGF mRNA levels in treated corneae compared to controls, whereas AGPT1+2–levels did not point out significant changes. Conclusions: Induction of corneal neovascularisation results in a strong increase of integrin alpha5–receptor expression of affected areas compared to physiologic corneae. Systemic delivery of alpha5beta1–inhibiting small molecule inhibits corneal neovascularisation induced by mechanical–alkali burn corneal injury. These results provide an essential role of integrin alpha5beta1 in pathological neovascular processes of the cornea and could be a new approach for treatment of neovascularisation in the eye.

Keywords: neovascularization • receptors: pharmacology/physiology