Hydrogen Sulfide Alleviates High-Salt-Stimulated Myocardial Fibrosis Through Inhibiting Hypoxia-Inducible Factor-1α

Qian Peng¹Pan Huang²Boyang Lv¹Chaoshu Tang³Hongfang Jin^1*Yaqian Huang^1*

• ¹First Hospital, Peking University, Beijing, China
• ²Capital Institute of Pediatrics, Beijing, Beijing Municipality, China
• ³Department of Physiology and Pathophysiology, School of Basic Medical Sciences, Health Science Centre, Peking University, Beijing, Beijing Municipality, China

Background: Endogenous hydrogen sulfide (H2S) and its key generating enzyme, cystathionine β-synthase (CBS), prevent vascular remodeling and damage to target organs during the advancement of hypertension induced by a high-salt diet.The contribution of the H₂S/CBS pathway to high-salt-induced myocardial fibrosis (MF) was explored, with a focus on the mechanistic involvement of hypoxiainducible factor-1α (HIF-1α).We used primary rat cardiac fibroblasts stimulated with high-salt medium and an MF model induced by a high-salt diet in Dahl salt-sensitive rats. Sodium hydrosulfide (NaHS), a commonly used H₂S donor, was administered in vitro at 100 μmol/L and in vivo at 90 µmol/kg to maintain adequate H₂S levels. An HIF-1α stabilizer, dimethyloxalylglycine (DMOG), was used to maintain the HIF-1α protein level. The H2S/CBS pathway was followed using western blotting and a sulfide-sensitive probe.The extent of MF was examined using histological and immunofluorescence staining techniques, including Sirius red and Masson trichrome. We performed western blot analysis to measure fibrosis-related protein and HIF-1α protein levels.Results: High-salt exposure reduced H₂S production and downregulated CBS protein expression in cardiac fibroblasts both in vitro and in vivo. In vitro, the H₂S donor inhibited the activation of cardiac fibroblasts triggered by high-salt conditions, while in vivo, it alleviated MF in salt-sensitive rats. From a mechanistic standpoint, high-salt exposure markedly upregulated HIF-1α expression. However, this increase was reversed by pretreatment with H2S. Furthermore, the HIF-1α stabilizer DMOG blocked the H2S-induced reduction in HIF-1α protein levels and consequently abolished the antifibrotic effect of H₂S on cardiac fibroblasts exposed to high-salt conditions.In conclusion, H₂S attenuates high-salt-induced MF by suppressing fibroblast activity and collagen synthesis, potentially via downregulation of HIF-1α.