Hydrogen sulfide-induced hypometabolism prevents renal ischemia/reperfusion injury

Abstract

Hydrogen sulfide (H(2)S) can induce a hypometabolic, hibernation-like state in mammals when given in subtoxic concentrations. Pharmacologically reducing the demand for oxygen is a promising strategy to minimize unavoidable hypoxia-induced injury such as ischemia/reperfusion injury during renal transplantation. Here we show that H(2)S reduces metabolism in vivo, ex vivo, and in vitro. Furthermore, we demonstrate the beneficial effects of H(2)S-induced hypometabolism in a model of bilateral renal ischemia/reperfusion injury using three different treatment strategies. The results demonstrate striking protective effects on survival, renal function, apoptosis, and inflammation. A hypometabolic state induced by H(2)S might have therapeutic potential to protect kidneys that suffer from hypoxia.

Figure 1.

Metabolic suppression by H₂S and experimental design. (A) Exposure to 100 ppm H₂S causes a rapid reduction in CO₂ production of a single mouse. (B) NRK-52E proximal tubular cells loaded with the mitochondrial membrane potential indicating fluorescent dye JC-1 were exposed to different concentrations of sodium hydrosulfide (a donor of H₂S in solution) for 20 min (**P < 0.01) (C and D) Rat kidneys in an isolated perfused kidney setup were exposed to 1 mM sodium hydrosulfide (n = 4) for 30 min, and O₂ consumption and ATP were compared with controls (n = 3) (*P < 0.05). (E) Schematic of experimental design showing different H₂S treatment regimens. (F) Relative CO₂ production of animals during the period of ischemia, corrected for body weight (n = 7) (**P < 0.01). (G) Average breathing frequency of animals 5 min before, during, and 30 min after ischemia (n = 5). Open circles indicate periods in which animals received 100 ppm H₂S.

Figure 2.

H₂S-induced hypometabolism prevents mortality and renal damage after renal ischemia. (A) Three-day survival of animals after reperfusion. (B) Renal function as measured by serum creatinine after 1 d of reperfusion. *P < 0.05 versus control, ^†P < 0.001 versus sham. (C) Apoptosis after 1 d of reperfusion was scored in sections stained for active Caspase 3 using immunohistochemistry. Apoptotic tubular cells were counted at 400× magnification in ten nonoverlapping fields (***P < 0.001). (D) Structural damage as assessed in periodic acid–Schiff-stained sections after 1 d of reperfusion. *P < 0.05 versus control, ***P < 0.001 versus control, ^†P < 0.001 versus sham. (E) Influx of leukocytes and granulocytes into the renal interstitium was scored in sections stained for Mac-1 (solid bars) or Ly-6G (dashed bars) using immunohistochemistry. *P < 0.05 versus control. (F through I) Representative photomicrographs of Ly-6G stained sections. (J through N) Representative periodic acid–Schiff-stained renal sections with necrotic area artificially colored red, indicating the extent of necrotic damage found in each group. [For B through E: sham (n = 5), control (n = 7), and H₂S-treated groups (n = 6)].