Oxidative Stress Participates in Age-Related Cataract Formation by Disrupting Connection between Lens Epithelial Cells through c-Src/VEGF Pathway.

ABSTRACT

PURPOSE: To observe the effects of oxidative stress on vascular endothelial growth factor (VEGF) and connections of lens epithelial cells. METHODS: Human lens epithelium of patients with age-related cataract (ARC), both SRA01/04 cells and whole mice lens stimulated by H2O2 were employed. VEGF in human aqueous humor of ARC-patients and the supernatant of SRA01/04 cells was determined by ELISA. The expressions of VEFG in human lens epithelium were detected by immunofluorescence staining. Multiple linear regression analysis and spearman rank-order correlation were used to determine the associations between VEGF and parameters of ARC individuals. In H2O2-induced SRA01/04 cells, Catalase (CAT), PP1 (inhibitor of c-Src kinase) and Avastin (VEGF antibody) were used to inhibit the effects of H2O2, activation of c-Src kinase and VEGF, which were detected by Western blot. The alterations of ZO-1 and N-cadherin were tested by immunofluorescence staining and Western blot. In H2O2-induced whole lens, the changes of opacification area in different treatment of inhibitors were observed. RESULTS: The secretion of VEGF in aqueous humor and expression of VEGF in the lens epithelium of ARC patients increased significantly with age. In H2O2-induced SRA01/04 cells, the VEGF in the supernatant was increased with the culture duration and the dose of H2O2. The expressions of p-Src418 and VEGF were also up-regulated, whereas the expressions of ZO-1 and N-cadherin were down-regulated. CAT effectively prevented these changes induced by H2O2, while PP1 inhibited not only p-Src418 but also up-regulation of VEGF, Avastin partially inhibited VEGF up-regulation. Both PP1 and Avastin prevented down-regulation of ZO-1 and N-cadherin, respectively, but Avastin combined with PP1 had no significant synergistic effects. In H2O2-induced cataract, CAT prevented development of opacification area effectively, and PP1 and Avastin did partially. CONCLUSIONS: Oxidative stress disrupts connections of lens epithelial cells by activating c-Src/VEGF, inhibiting which may prevent cataract.