Hydrogen sulfide attenuates oxidative stress-induced cellular senescence via the Sirt3/SOD2 signaling pathway in chronic obstructive pulmonary disease.

Abstract

Background: Senescence significantly participates in shaping the pathobiological process underlying chronic obstructive pulmonary disease (COPD). Currently, the mechanisms underlying the anti-aging effects within COPD of hydrogen sulfide (H2S) are not fully illustrated.

Methods: Immunohistochemistry (IHC) staining was performed on human lung tissue to detect the expression levels of sirtuin 3 (Sirt3), cyclin-dependent kinase 4 inhibitor (P16), and cystathionin gamma lyase (CTH). An animal model including wild-type (WT) and Sirt3 knockout (KO) mice was established by exposing them to cigarette smoking (CS) for 24 weeks, with or without intraperitoneal injection of sodium hydrosulfide (NaHS, 50 µmol∙L-1∙kg-1) 30 min prior to CS exposure. Lung function was assessed. The expression levels of P16, cyclin-dependent kinase inhibitor 1 (P21), Sirt3, manganese superoxide dismutase (SOD2), manganese acetylated superoxide dismutase (ac-SOD2), interleukin-6 (IL-6), IL-8, malondialdehyde (MDA), and glutathione (GSH), as well as the activity of SOD2 and Sirt3, were evaluated. Human bronchial epithelial BEAS-2B cells were subjected to diverse cigarette smoking extract (CSE) concentrations for 48 h with or without sodium hydrosulfide (NaHS). Subsequently, the levels of total intracellular reactive oxygen species (T-ROS), mitochondrial reactive oxygen species (mitoROS), mitochondrial membrane potential (MMP), senescence-associated β-galactosidase (SA-β-gal) staining positive cells, and related marker proteins and cytokines were assessed. Furthermore, the Sirt3-specific inhibitor 3-TYP and small interfering RNAs (siRNAs) of Sirt3 were used to examine the mechanisms whereby H2S inhibits oxidative stress and senescence in COPD.

Results: IHC showed a significant reduction of CTH and Sirt3 protein levels in the lung tissue of COPD with smoking patients and smokers without COPD compared to non-smokers. Furthermore, the expression of the aging marker protein P16 was notably elevated in the COPD with smoking group compared to the smokers without COPD and non-smoker groups. Furthermore, our results demonstrated that exposure to CS resulted in imbalanced oxidative and cellular senescence, including elevated mitoROS, T-ROS, MDA, and ac-SOD2, along with increased proportions of SA-β-gal staining positive cells and the increased expression levels of IL-6, IL-8, P21, and P16, as well as decreased GSH levels, SOD2 and Sirt3 activities, and Sirt3 expression, which ultimately contribute to emphysema development and impaired lung function. However, pretreatment with NaHS effectively reversed these detrimental effects. Nevertheless, the protective effect of NaHS was alleviated in Sirt3 KO mice and in cellular models treated with Sirt3 siRNA and 3-TYP.

Conclusion: Our study indicates that H2S inhibits oxidative stress and cellular senescence by modulating the Sirt3/SOD2 signaling pathway, therefore attenuating the emphysema and impaired lung function induced by CS.