INHIBITION OF RETINAL-PIGMENT EPITHELIAL CELL-INDUCED TRACTIONAL RETINAL-DETACHMENT BY DISINTEGRINS, A GROUP OF ARG-GLY-ASP-CONTAINING PEPTIDES FROM VIPER VENOM

Purpose. Integrin-mediated extracellular matrix (ECM) attachment plays an important role in vitreous contraction of retinal pigment epitheli al (RPE) cells. Disintegrins, a group of Arg-Gly-Asp (RGD)containing p eptides from viper venom, are potential anti-adhesion agents that inte rfere with integrin-ECM binding. This study was performed to determine whether disintegrins were effective in inhibiting RPE cell-induced ma trix attachment in vitro and tractional retinal detachment in a rabbit model in vivo. Methods. Two disintegrins, echistatin from viper Echis carinalus and flavoridin from Trimeresurus flavoviridis, were used. T he expression of integrins on the surface of bovine and rabbit RPE cel ls was examined by indirect immunofluorescent stain with specific anti -integrin monoclonal antibodies. The inhibitory effect of disintegrins on RPE cell-mediated ECM attachment and vitreous contraction was eval uated with cell adhesion and vitreous contraction assays. In the in vi vo model, rabbit eyes were injected intravitreously with either homolo gous rabbit RPE cells alone or together with disintegrins to induce tr actional retinal detachment The cytotoxic effect of disintegrins was e xamined with a cell proliferation assay using the alamar blue method. Retinal toxicity of disintegrins was evaluated with electroretinograms and histologic examination of the rabbit eyes. Results, Bovine and ra bbit RPE cells showed the positive staining for the integrins alpha(2) beta(1) and alpha(5) beta(1) on cell surface. Disintegrins, echistati n, and flavoridin inhibited RPE cell attachment to the ECM. The potenc y of disintegrins was 150 to 300 times higher than that of Gly-Arg-Gly -Asp-Ser (GRGDS) peptide. The disintegrins also inhibited RPE cell-ind uced vitreous contraction in a dose-dependent manner, whereas the GRGD S peptide had no effect. In the in vivo experiment, echistatin (50 mu g/ml) or flavoridin (80 mu g/ml) significantly inhibited RPE cell-indu ced tractional retinal detachment compared with the control group at w eek 2 (P < 0.05) and week 4 (P < 0.01) after surgery. Disintegrins wer e nontoxic to RPE cells and rabbit retina as evaluated by cytotoxicity tests, electroretinograms, and histologic examinations. Conclusions, The disintegrins were effective in inhibiting RPE cell attachment to t he ECM and vitreous contraction in vitro. They also were effective in suppressing RPE cell-induced tractional retinal detachment in the rabb it eyes. They were nontoxic. Disintegrins and their analogs might be p otential anti-adhesion therapeutic agents in the treatment of prolifer ative vitreoretinopathy.