AIM: To study the effects of FOXO4 on oxidative stress and apoptosis of retinal vascular endothelial cells under high glucose environmental conditions.

METHODS: Human retinal vascular endothelial cells were cultured with high glucose medium. Real-time PCR and Western blot were used to detect the expressions of FOXO4 within cells; meanwhile, both FOXO4 RNAi lentivirus and control vector lentivirus were infected the retinal vascular endothelial cells cultured in high sugar culture medium. Real-time PCR and Western blot techniques were used to detect the interference efficiency. After collection of supernatant and cells treated with various interferences, the SOD activity, MDA content in the supernatants and ROS level within cells were detected. Flow cytometry was used to determine the changes of cell apoptosis. Western blot was used to detect the expressions of apoptotic protein cleaved Caspase-3 and cleaved Caspase-9 within cells.

RESULTS: The expression of FOXO4 was increased in retinal vascular endothelial cells after treatment with high glucose medium. FOXO4 RNAi lentivirus infection reduced the expression level of FOXO4 in retinal vascular endothelial cells under high glucose environmental conditions. By contrast, control vector lentivirus had no effect on FOXO4 expression in cells. High glucose induced elevated levels of ROS in retinal vascular endothelial cells, reduced the activity of SOD in cell culture medium, increased the content of MDA, elevated the rate of apoptosis, and promoted the expressions of cleaved Caspase-3 and cleaved Caspase-9 proteins in cells. After down-regulation of FOXO4 expression, retinal endothelial cells were induced by high glucose, the activity of SOD in the cell culture medium increased, the levels of MDA, ROS, apoptosis, and the levels of cleaved Caspase-3 and cleaved Caspase-9 proteins decreased in cells as compared with those of retinal vascular endothelial cells. Moreover, compared with those did not interfere with FOXO4 expression, there was statistically significant differences(P<0.05).

CONCLUSION: High glucose induces the expression of FOXO4 in retinal vascular endothelial cells. Knocking-down of FOXO4 expression reduces oxidative stress and apoptosis induced by high glucose medium.