Hydrogen sulfide (H2S) alleviates diabetic myocardial fibrosis by suppressing pyroptosis via inhibiting DNMT3a-mediated Sestrin2 CpG promoter hypermethylation

Background

Diabetic cardiomyopathy (DCM) represents an important concern associated with diabetes, inhibiting pyroptosis has shown promising results in alleviating DCM symptoms. The objective of this work is to investigate the role and underlying mechanism of hydrogen sulfide (H₂S) in the suppression of pyroptosis in the context of diabetic myocardial fibrosis (MF).

Methods

The effect of H₂S on pyroptosis was detected using CCK-8, ELISA, and flow cytometry. The expression of Sestrin2 and its DNA methylation modification, as well as the quantification of pyroptosis-related proteins and the activation of the TLR4/MyD88/NF-κB signaling pathway, were measured using Western blot, ChIP, Immunofluorescence, and methylation-specific quantitative PCR. To establish a type 2 diabetes rat model, a high-fat diet was administered, followed by injection of streptozotocin (HFD/STZ). After five weeks, the rats received H₂S treatment for four weeks, either with or without sh-Sestrin2. The effects of H₂S treatment on myocardial function, tissue structure, and myocardial cell apoptosis were assessed. Furthermore, the CCK-8 assay was used to detect the cell viability induced by TGF-β. Cellular oxidative stress levels were measured by the ELISA method. Western blotting was applied to determine the protein expression levels of Collagen I, Fibronectin, α-SMA, NLRP3, caspase-1, GSDMD-N, and Sestrin2.

Results

H₂S ameliorates HG-induced fibrosis, injury, pyroptosis, and inflammatory response of cardiac fibroblasts (CFs). H₂S inhibits Sestrin2 methylation and up-regulates its expression through DNMT3a. H₂S ameliorates HG-induced CFs pyroptosis and fibrosis through Sestrin2. Sestrin2 regulates HG-induced CFs pyroptosis and fibrosis through the TLR4/MyD88/NF-κB pathway. The myocardial tissue injury was improved after H₂S treatment, and the results of the H₂S treatment were reversed after knockdown of Sestrin2. In addition, TGF-β1 can induce an increase in the activity of cardiac fibroblasts and enhance cellular oxidative stress. Meanwhile, it significantly upregulates the expression of Collagen I, Fibronectin, α-SMA, as well as NLRP3, caspase-1, and GSDMD-N, and remarkably downregulates the expression of Sestrin2. However, H₂S intervention can reverse the aforementioned phenomena.

Conclusion

H₂S can suppress pyroptosis and ameliorate diabetic MF by inhibiting DNMT3a-mediated DNA methylation of Sestrin2 promoter through the TLR4/MyD88/NF-κB pathway.