Protective role of glutathione peroxidase 4 in laser-induced choroidal neovascularization in mice.

Abstract

PURPOSE: To evaluate the influence of glutathione peroxidase 4 (GPx4) expression in retinal pigment epithelium (RPE)/choroid tissue using a mouse model of laser-induced choroidal neovascularization (CNV). METHODS: In this study, GPx4+/-, GPx4+/+, and GPx4-overexpressing transgenic mice were created for comparison. The mRNA and protein expression of vascular endothelial growth factor (VEGF)-A in RPE/choroid tissue were evaluated before and after CNV induction by laser. Moreover, we investigated the changes in the VEGF-A mRNA level in RPE/choroid tissue in the CNV model that have not been clearly shown previously. Lipid peroxidation in RPE/choroid tissue was evaluated by immunohistochemistry using antibody against 4-hydroxy-2-nonenal. To investigate the protective role of GPx4, the size of laser-induced CNV was compared on day 7 among the mice expressing different levels of GPx4. RESULTS: In the laser-induced CNV mouse model, laser treatment reduced the VEGF-A mRNA level in RPE/choroid tissue, while it increased the VEGF-A protein level. Evaluation of VEGF-A expression in RPE/choroid tissue of the GPx4+/-, GPx4+/+, and GPx4 transgenic mice revealed that GPx4 increased the VEGF-A protein level under physiological conditions (i.e., without laser treatment), while GPx4 suppressed the increase in the VEGF-A protein level under pathological conditions (i.e., after CNV induction by laser). In addition, GPx4 reduced the CNV size in a dose-dependent manner in vivo. CONCLUSIONS: GPx4 suppresses the increase in the VEGF-A protein level, which occurs during the development of pathological CNV, thus partly explaining the protective effect of GPx4 against CNV.