Hydrogen Sulfide Regulates Alveolar Epithelial Cell Senescence In Bleomycin-induced Pulmonary Via MDM2 S-sulfhydration

Objective:Pulmonary fibrosis is a typical common pathological feature in lung diseases.Hydrogen sulfide?H₂S?is considered to be the third member of the gas transport family after nitric oxide and carbon monoxide.It plays an extremely important role in many physiological and pathophysiological processes including inflammation,metabolic disorders,and blood pressure regulation.Previous experiments by this us have shown that H₂S donor NaHS can reverse cell senescence in bleomycin-induced pulmonary fibrosis both in vivo and in vitro.The purpose of this study is to further elucidate how H₂S can regulate the senescence of alveolar epithelial cells and thus control pulmonary fibrosis from the mechanism.Methods:CBS knockout mice were constructed,and the expression of P53,P21,and CSE in lung tissues was detected by WB,the degree of pulmonary fibrosis was observed by Masson staining,and the co-expression of P53,P21 proteins and SPC in lung tissues was observed by immunofluorescence.The supernatant of the L2 cells was collected and act on NIH3T3.The expression of?-SMA and Fibronectin in fibroblasts was detected by WB,and the gene expression of proliferation-specific mRNAs Aurkb,Ccnb1,Cdc25b,and Foxm1 in fibroblasts were detected by PCR.In order to understand the key role of P53 in bleomycin-induced pulmonary fibrosis,L2cells were treated with P53 inhibitors and hydrogen sulfide.Cell senescence was detected by detecting P21 protein expression and SA-?-gal aging staining in cells.Co-immunoprecipitation was used to understand the interaction between P53 and MDM2 and the ubiquitination of P53 after H₂S treatment.Finally,the lung tissues of mice treated with BLM and H₂S were subjected to S-sulfhydration to clarify the S-sulfhydration effect of H₂S.Results:1)H₂S synthase CBS knockout can induce senescence and pulmonary fibrosis in type II lung epithelial cells;2)H₂S donor NaHS inhibits the interaction between ATII cells and fibroblasts;3)P53 inhibitors can reverse Aging;4)H₂S donor NaHS promotes P53ubiquitination by enhancing MDM2 S-sulfhydration.Conclusion:H₂S can inhibit the abnormal proliferation of NIH3T3,and regulates alveolar epithelial cell senescence in bleomycin-induced pulmonary via MDM2 S-sulfhydration.