Hydrogen Sulfide Attenuates Hydrogen Peroxide-Induced Injury in Human Lung Epithelial A549 Cells

Lung tissues are frequently exposed to a hyperoxia environment, which leads to oxidative stress injuries. Hydrogen sulfide (H2S) is widely implicated in physiological and pathological processes and its antioxidant effect has attracted much attention. Therefore, in this study, we used hydrogen peroxide (H2O2) as an oxidative damage model to investigate the protective mechanism of H2S in lung injury. Cell death induced by H2O2 treatment could be significantly attenuated by the pre-treatment of H2S, resulting in a decrease in the Bax/Bcl-2 ratio and the inhibition of caspase-3 activity in human lung epithelial cell line A549 cells. Additionally, the results showed that H2S decreased reactive oxygen species (ROS), as well as neutralized the damaging effects of H2O2 in mitochondria energy-producing and cell metabolism. Pre-treatment of H2S also decreased H2O2-induced suppression of endogenous H2S production enzymes, cystathionine-beta-synthase (CBS), cystathionine-gamma-lyase (CSE), and 3-mercapto-pyruvate sulfurtransferase (MPST). Furthermore, the administration of H2S attenuated [Ca2+] overload and endoplasmic reticulum (ER) stress through the mitogen-activated protein kinase (MAPK) signaling pathway. Therefore, H2S might be a potential therapeutic agent for reducing ROS and ER stress-associated apoptosis against H2O2-induced lung injury.