Chlorogenic acid attenuates hydrogen peroxide-induced oxidative stress in lens epithelial cells

Oxidative stress has an important role in the degradation, oxidation, cross-linking and aggregation of lens proteins, and can trigger lens epithelial cell apoptosis. To investigate the protective effect of chlorogenic acid (CGA) against hydrogen peroxide (H(2)O(2))-induced oxidative stress, human lens epithelial cells (hLECs) were exposed to various concentrations of H(2)O(2) in the presence and absence of CGA. Using MTT assay, reverse transcription-quantitative polymerase chain reaction (RT-qPCR) and ELISA techniques, cell viability, and protein/mRNA levels of BCL2 apoptosis regulator (Bcl-2) and BCL2 associated X apoptosis regulator (Bax) were investigated. Additionally, the levels of intracellular reactive oxygen species (ROS) and apoptosis within cells were measured using flow cytometry to determine the protective effect of CGA on H(2)O(2)-induced oxidative stress. Furthermore, the protective effect of CGA on H(2)O(2)-induced apoptosis was also examined using rabbit lenses ex vivo. The results indicated that CGA reduced H(2)O(2)-induced cytotoxicity in a dose-dependent manner. Flow cytometry analysis demonstrated that simultaneous exposure of hLECs to H(2)O(2) and CGA significantly decreased apoptosis and the levels of ROS. RT-qPCR analysis revealed a decrease in Bcl-2 and an increase in Bax in hLECs following exposure to H(2)O(2) for 24 h, regardless of CGA presence. Furthermore, ELISA results indicate that CGA increased Bcl-2 expression and decreased Bax expression following treatment with H(2)O(2) for 24 h and the Bax/Bcl-2 ratio was significantly decreased by CGA treatment. Lens organ culture experiments indicated a dose-dependent decrease in H(2)O(2)-induced lens opacity following CGA treatment. These results suggest that CGA suppresses hLECs apoptosis and prevents lens opacity induced by H(2)O(2) via Bax/Bcl-2 signaling pathway. CGA may provide effective defenses against oxidative stress and, thus, haσ potential as treatment for a variety of diseases in clinical practice.