Lycium barbarum Polysaccharides Protect Human Lens Epithelial Cells against Oxidative Stress–Induced Apoptosis and Senescence

OBJECTIVES: We aimed to investigate the protective effect of Lycium barbarum polysaccharides (LBPs) against oxidative stress–induced apoptosis and senescence in human lens epithelial cells. METHODS: To study apoptosis, SRA01/04 cells, a human lens epithelial cell lines, were exposed to 200 µM hydrogen peroxide (H(2)O(2)) for 24 h with or without pretreatment with LBPs. Cell viability was measured using a Cell Counting Kit-8 (CCK-8) assay. Cell apoptosis, intracellular reactive oxygen species (ROS), and the loss of mitochondria membrane potential (Δψm) were detected by flow cytometric analyses. Expression levels of Bcl-2 and Bax proteins were measured by western blot analysis. The levels of malondialdehyde (MDA), superoxide dismutase (SOD), and glutathione (GSH) were quantized using commercial enzymatic kits according to the manufacturer's instructions. To study senescence, SRA01/04 cells were pre-incubated with LBPs and all cells were then exposed to 100 µM H(2)O(2) for 96 h. Cellular senescence was assessed by morphologic examination and senescence-associated β-galactosidase (SA-β-gal) staining. RESULTS: LBPs significantly reduced H(2)O(2)-induced cell apoptosis, the generation of ROS, the loss of Δψm, and the levels of MDA. LBPs also inhibited H(2)O(2)-induced downregulated Bcl-2 and upregulated Bax proteins and increased the levels of SOD and GSH enzyme activity. Moreover, LBPs significantly attenuated H(2)O(2)-induced cellular senescence. CONCLUSIONS: These findings suggested that LBPs protect human lens epithelial cells from H(2)O(2)-induced apoptosis by modulating the generation of ROS, loss of Δψm, Bcl-2 family, and antioxidant enzyme activity and attenuating cellular senescence.