Pauline M. Snijder

Gaseous Hydrogen Sulfide Protects against Myocardial Ischemia-Reperfusion Injury in Mice Partially Independent from Hypometabolism

Background Ischemia-reperfusion injury (IRI) is a major cause of cardiac damage following various pathological processes. Gaseous hydrogen sulfide (H2S) is protective during IRI by inducing a hypometabolic state in mice which is associated with anti-apoptotic, anti-inflammatory and antioxidant properties. We investigated whether gaseous H2S administration is protective in cardiac IRI and whether non-hypometabolic concentrations of H2S have similar protective properties. Methods Male C57BL/6 mice received a 0, 10, or 100 ppm H2S-N2 mixture starting 30 minutes prior to ischemia until 5 minutes pre-reperfusion. IRI was inflicted by temporary ligation of the left coronary artery for 30 minutes. High-resolution respirometry equipment was used to assess CO2-production and blood pressure was measured using internal transmitters. The effects of H2S were assessed by histological and molecular analysis. Results Treatment with 100 ppm H2S decreased CO2-production by 72%, blood pressure by 14% and heart rate by 25%, while treatment with 10 ppm H2S had no effects. At day 1 of reperfusion 10 ppm H2S showed no effect on necrosis, while treatment with 100 ppm H2S reduced necrosis by 62% (p<0.05). Seven days post-reperfusion, both 10 ppm (p<0.01) and 100 ppm (p<0.05) H2S showed a reduction in fibrosis compared to IRI animals. Both 10 ppm and 100 ppm H2S reduced granulocyte-influx by 43% (p<0.05) and 60% (p<0.001), respectively. At 7 days post-reperfusion both 10 and 100 ppm H2S reduced expression of fibronectin by 63% (p<0.05) and 67% (p<0.01) and ANP by 84% and 63% (p<0.05), respectively. Conclusions Gaseous administration of H2S is protective when administered during a cardiac ischemic insult. Although hypometabolism is restricted to small animals, we now showed that low non-hypometabolic concentrations of H2S also have protective properties in IRI. Since IRI is a frequent cause of myocardial damage during percutaneous coronary intervention and cardiac transplantation, H2S treatment might lead to novel therapeutical modalities.

Exogenous administration of thiosulfate, a donor of hydrogen sulfide, attenuates angiotensin II-induced hypertensive heart disease in rats.

Hypertension is an important mediator of cardiac damage and remodelling. Hydrogen sulfide (H2S) is an endogenously produced gasotransmitter with cardioprotective properties. However, it is not yet in clinical use. We, therefore, investigated the protective effects of sodium thiosulfate (STS), a clinically applicable H2S donor substance, in angiotensin II (Ang II)‐induced hypertensive cardiac disease in rats.

Sodium thiosulfate attenuates angiotensin II-induced hypertension, proteinuria and renal damage.

Hypertension and proteinuria are important mediators of renal damage. Despite therapeutic interventions, the number of patients with end stage renal disease steadily increases. Hydrogen sulfide (H(2)S) is an endogenously produced gasotransmitter with vasodilatory, anti-inflammatory and antioxidant properties. These beneficial characteristics make H(2)S an attractive candidate for pharmacological use in hypertensive renal disease. We investigated the protective properties of H(2)S in angiotensin II (Ang II)-induced hypertensive renal disease in rats. Treatment with the H(2)S donor NaHS and major H(2)S metabolite sodium thiosulfate (STS) during three weeks of Ang II infusion reduced hypertension, proteinuria, oxidative stress and renal functional and structural deterioration. In an ex vivo isolated perfused kidney setup, NaHS, but not STS, reduced intrarenal pressure. The effect of NaHS could partially be explained by its activation of the ATP-sensitive potassium channels. In conclusion, treatment with H(2)S attenuates Ang II-associated functional and structural renal deterioration, suggesting that intervention in H(2)S production pathways has potential therapeutic benefit and might be a valuable addition to the already existing antihypertensive and renoprotective therapies.

Beneficial effects of gaseous hydrogen sulfide in hepatic ischemia/reperfusion injury

Hydrogen sulfide (H2S) can induce a reversible hypometabolic state, which could protect against hypoxia. In this study we investigated whether H2S could protect livers from ischemia/reperfusion injury (IRI). Male C57BL/6 mice were subjected to partial hepatic IRI for 60 min. Animals received 0 (IRI) or 100 ppm H2S (IRI + H2S) from 30 min prior to ischemia until 5 min before reperfusion. Core body temperature was maintained at 37 °C. Animals were sacrificed after 1, 6 or 24 h. Hepatic ischemia caused extensive hepatic necrosis in the IRI animals which coincided with an increase in ALT and AST serum levels. Animals treated with H2S showed attenuated serum ALT and AST levels and reduced necrotic lesions after 24 h. IRI animals had increased Bcl‐2 mRNA expression and increased active Caspase 3 protein, which were both significantly lower in H2S treated animals. Increased TNFα and IL‐6 mRNA in the IRI livers was significantly attenuated by H2S treatment, as was hepatic influx of Ly‐6G positive granulocytes. Hepatic superoxide production after ischemia was attenuated by H2S treatment. In hepatic ischemia/reperfusion injury, gaseous H2S treatment is highly protective, substantially reducing necrosis, apoptosis and inflammation. Gaseous H2S is therefore a very promising treatment for reducing IRI during hepatic transplantation.

Emerging Role of Gasotransmitters in Renal Transplantation

Once patients with kidney disease progress to end‐stage renal failure, transplantation is the preferred option of treatment resulting in improved quality of life and reduced mortality compared to dialysis. Although 1‐year survival has improved considerably, graft and patient survival in the long term have not been concurrent, and therefore new tools to improve long‐term graft and patient survival are warranted. Over the past decades, the gasotransmitters nitric oxide (NO), carbon monoxide (CO) and hydrogen sulfide (H2S) have emerged as potent cytoprotective mediators in various diseases. All three gasotransmitters are endogenously produced messenger molecules that possess vasodilatory, anti‐apoptotic, anti‐inflammatory and anti‐oxidant properties by influencing an array of intracellular signaling processes. Although many regulatory functions of gasotransmitters have overlapping actions, differences have also been reported. In addition, crosstalk between NO, CO and H2S results in synergistic regulatory effects. Endogenous and exogenous manipulation of gasotransmitter levels modulates several processes involved in renal transplantation. This review focuses on mechanisms of gas‐mediated cytoprotection and complex interactions between gasotransmitters in renal transplantation.

dl-propargylglycine reduces blood pressure and renal injury but increases kidney weight in angiotensin-II infused rats

Hydrogen sulfide (H2S), carbon monoxide (CO) and nitric oxide (NO) share signaling and vasorelaxant properties and are involved in proliferation and apoptosis. Inhibiting NO production or availability induces hypertension and proteinuria, which is prevented by concomitant blockade of the H2S producing enzyme cystathionine γ-lyase (CSE) by d,l-propargylglycine (PAG). We hypothesized that blocking H2S production ameliorates Angiotensin II (AngII)-induced hypertension and renal injury in a rodent model. Effects of concomitant administration of PAG or saline were therefore studied in healthy (CON) and AngII hypertensive rats. In CON rats, PAG did not affect systolic blood pressure (SBP), but slightly increased proteinuria. In AngII rats PAG reduced SBP, proteinuria and plasma creatinine (180 ± 12 vs. 211 ± 19 mmHg; 66 ± 35 vs. 346 ± 92 mg/24 h; 24 ± 6 vs. 47 ± 15 μmol/L, respectively; p < 0.01). Unexpectedly, kidney to body weight ratio was increased in all groups by PAG (p < 0.05). Renal injury induced by AngII was reduced by PAG (p < 0.001). HO-1 gene expression was increased by PAG alone (p < 0.05). PAG increased inner cortical tubular cell proliferation after 1 week and decreased outer cortical tubular nucleus number/field after 4 weeks. In vitro proximal tubular cell size increased after exposure to PAG. In summary, blocking H2S production with PAG reduced SBP and renal injury in AngII infused rats. Independent of the cardiovascular and renal effects, PAG increased HO-1 gene expression and kidney weight. PAG alone increased tubular cell size and proliferation in-vivo and in-vitro. Our results are indicative of a complex interplay of gasotransmitter signaling/action of mutually compensatory nature in the kidney.