Hydrogen Sulfide Inhibits H₂O₂-induced Senescence Of Human Umbilical Vascular Endothelial Cells Through Activation Of The SIRT1/FoxO1 Pathway

[Background and objective] Cardiovascular disease is the leading cause of death worldwide, with aging as the key independent risk factor. Exploring the mechanisms and effective interventions against aging are important for prevention and treatment of cardiovascular disease. It has been reported that hydrogen sulfide(H2S) has an inhibitory effect on aging, but the underlying mechanisms remain largely unclear. Sirtuin1(SIRT1), a highly conserved NAD+-dependent protein deacetylase, could resist to oxidative stress through deacetylating forkhead box O transcription factor 1(Fox O1) and retard aging. H2 S plays a role in regulating the expression and activity of SIRT1. This study aimed to explore whether activation of SIRT1/Fox O1 signaling is involved in H2S-inhibited senescence of human umbilical vascular endothelial cells(HUVECs) induced by hydrogen peroxide(H2O2).[Methods and results] 1. The senescence of HUVECs was induced by treatment with 100 μM H2O2 for 1 h. The percentage of SA-β-gal positive cells in the H2O2-treated HUVECs was increased by 7.4 folds, compared with that in the control group(P < 0.01). The protein expression of p53, p21 and plasminogen activator inhibitor-1(PAI-1) in the H2O2-treated group, as detected by western blot analysis, was obviously enhanced by 60.5%, 5.8 and 1.6 folds, respectively, compared with those in the control group(P < 0.01). 2. Pretreatment of HUVECs with 100 μM Na HS for 30 min significantly inhibited H2O2-induced the SA-β-gal positive cells and the protein expression of p53, p21 and PAI-1 by 43.8%, 49.7%, 49.4% and 67.6%, respectively(P < 0.01). 3. Compared with those in the control group, the protein expression of SIRT1, Fox O1, Mn SOD and catalase was significantly reduced by 61.4%, 28.3%, 43.9% and 45.4%, respectively(P < 0.05), whereas the ratio of Ac-Fox O1/Fox O1 and the level of reactive oxygen species(ROS) detected by DCFH-DA fluorescent probe were markedly enhanced by 84% and 2.8 folds respectively(P < 0.01) in H2O2 group. On the other hand, the protein expression of SIRT1, Fox O1, Mn SOD and catalase was increased by 2.2 folds, 84.1%, 38% and 38.7%, respectively(P < 0.01), and the ratio of Ac-Fox O1/ Fox O1 and the level of ROS were decreased by 48.4% and 46.2%, respectively(P < 0.05), in H2O2+Na HS group, compared with those in H2O2 group. In addition, compared with those in the control and H2O2 group, the S-sulfhydration of SIRT1 was evidently increased in H2O2+Na HS group(P < 0.01). 4. After preincubation with 50 n M Fox O1 si RNA for 24 h, the SA-β-gal positive cells, the protein expression of p53, p21 and PAI-1, and the level of ROS were significantly enhanced by 39%, 65.5%, 1.9, 1.5 and 1.6 folds, respectively(P < 0.01), while the protein expression of Mn SOD and catalase was remarkably reduced by 80% and 67.6%, respectively(P<0.01), in H2O2+Na HS+Fox O1 si RNA group compared to the H2O2+Na HS group.[Conclusions] H2 S inhibits HUVECs senescence induced by H2O2 via up-regulation of SIRT1 expression and S-sulfhydration of SIRT1, which, in turn, lowers the acetylation level of Fox O1, increases the expressions of Mn SOD, catalase and decreases oxidative stress through reduced the production of ROS.