Exogenous hydrogen sulfide prevents SOD2 degradation to safeguard renal function in diabetic kidney disease

Diabetic kidney disease (DKD) is a major contributor to chronic kidney disease. Hydrogen sulfide (H₂S) serves as an endogenous gaseous signaling molecule capable of safeguarding renal function within the context of DKD. However, the underlying mechanisms need to be elucidated. This study was undertaken to unveil the mechanisms by which H₂S counteracts against DKD. Utilizing mice and human renal tubular epithelial (HK-2) cells, we demonstrated a reduction in cystathionine-γ-lyase/H₂S levels within renal tissues of db/db mice and in HK-2 cells subjected to hyperglycemic and hyperlipidemic environments. Notably, we observed that sodium hydrosulfide (NaHS) supplementation could serve as an exogenous source of H₂S. Exogenous H₂S exhibited the capacity to mitigate the accumulation of reactive oxygen species and attenuate the degradation of superoxide dismutase 2 (SOD2) by Lon protease homolog 1 induced by hyperglycemia and hyperlipidemia, thus affording cellular protection against mitochondrial apoptosis. Consequently, NaHS treatment led to decreased serum levels of blood urea nitrogen and serum creatinine, reflecting alleviated renal damage and thereby preserving renal function in db/db mice. Based on these findings, we propose that exogenous H₂S exerts a protective role against DKD by inhibiting SOD2 degradation.