Protective effect of hydrogen sulfide on renal injury in the experimental unilateral ureteral obstruction

Evaluating the Effects of Kidney Preservation at 10 °C with Hemopure and Sodium Thiosulfate in a Rat Model of Syngeneic Orthotopic Kidney Transplantation

Kidney transplantation is preferred for end-stage renal disease. The current gold standard for kidney preservation is static cold storage (SCS) at 4 °C. However, SCS contributes to renal graft damage through ischemia-reperfusion injury (IRI). We previously reported renal graft protection after SCS with a hydrogen sulfide donor, sodium thiosulfate (STS), at 4 °C. Therefore, this study aims to investigate whether SCS at 10 °C with STS and Hemopure (blood substitute), will provide similar protection. Using in vitro model of IRI, we subjected rat renal proximal tubular epithelial cells to hypoxia-reoxygenation for 24 h at 10 °C with or without STS and measured cell viability. In vivo, we preserved 36 donor kidneys of Lewis rats for 24 h in a preservation solution at 10 °C supplemented with STS, Hemopure, or both followed by transplantation. Tissue damage and recipient graft function parameters, including serum creatinine, blood urea nitrogen, urine osmolality, and glomerular filtration rate (GFR), were evaluated. STS-treated proximal tubular epithelial cells exhibited enhanced viability at 10 °C compared with untreated control cells (p < 0.05). Also, STS and Hemopure improved renal graft function compared with control grafts (p < 0.05) in the early time period after the transplant, but long-term function did not reach significance. Overall, renal graft preservation at 10 °C with STS and Hemopure supplementation has the potential to enhance graft function and reduce kidney damage, suggesting a novel approach to reducing IRI and post-transplant complications.

The roles of hydrogen sulfide in renal physiology and disease states

Hydrogen sulfide (H₂S), an endogenous gaseous signaling transmitter, has gained recognition for its physiological effects. In this review, we aim to summarize and discuss existing studies about the roles of H₂S in renal functions and renal disease as well as the underlying mechanisms. H₂S is mainly produced by four pathways, and the kidneys are major H₂S–producing organs. Previous studies have shown that H₂S can impact multiple signaling pathways via sulfhydration. In renal physiology, H₂S promotes kidney excretion, regulates renin release and increases ATP production as a sensor for oxygen. H₂S is also involved in the development of kidney disease. H₂S has been implicated in renal ischemia/reperfusion and cisplatin–and sepsis–induced kidney disease. In chronic kidney diseases, especially diabetic nephropathy, hypertensive nephropathy and obstructive kidney disease, H₂S attenuates disease progression by regulating oxidative stress, inflammation and the renin–angiotensin–aldosterone system. Despite accumulating evidence from experimental studies suggesting the potential roles of H₂S donors in the treatment of kidney disease, these results need further clinical translation. Therefore, expanding the understanding of H₂S can not only promote our further understanding of renal physiology but also lay a foundation for transforming H₂S into a target for specific kidney diseases.

Protective effect of H2S on LPS‑induced AKI by promoting autophagy

The present study explored the protective effect of exogenous hydrogen sulfide (H2S) on lipopolysaccharide (LPS)‑induced acute kidney injury (AKI) and the underlying mechanisms. To establish an AKI injury mouse model, LPS (10 mg/kg) was intraperitoneally injected into mice pretreated with 0.8 mg/kg sodium hydrosulfide hydrate (NaHS), an H2S donor. The mouse survival rate and the degree of kidney injury were examined. To construct a cell damage model, HK‑2 cells were pretreated with different concentrations (0.1, 0.3 and 0.5 mM) of NaHS, and then the cells were stimulated with LPS (1 µg/ml). The cell viability, autophagy, apoptosis levels and the release of inflammatory factors were examined in mouse kidney tissue and HK‑2 renal tubular epithelial cells. It was found that pretreatment with NaHS significantly improved the survival rate of septic AKI mice, and reduced the renal damage, release of inflammatory factors and apoptosis. In HK‑2 cells, NaHS protected cells from LPS caused damage via promoting autophagy and inhibiting apoptosis and the release of inflammatory factors. In order to clarify the relationship between autophagy and apoptosis and inflammatory factors, this study used 3‑methyladenine (3‑MA) to inhibit autophagy. The results revealed that 3‑MA eliminated the protective effect of NaHS in HK‑2 cells and AKI mice. Overall, NaHS can protect from LPS‑induced AKI by promoting autophagy and inhibiting apoptosis and the release of inflammatory factors.

Role of Hydrogen Sulfide in the Treatment of Fibrosis

Hydrogen sulfide (H₂S) is a biological gas, the abnormal metabolism of which has associations with the pathogenesis of fibrosis. The purpose of this paper was to determine the potential of H₂S in the prevention and treatment of fibrosis. The data is obtained mainly from articles found in the PubMed database using the keywords “fibrosis” and “hydrogen sulfide,” limiting the results to those published within the last 10 years. Some additional resources have also been used, such as books and articles within journals. Evidence of decreased H₂S enzyme levels in animal models with fibrotic diseases has been found. The protective role of H₂S has been validated by the administration of exogenous H₂S donors in animal models with fibrosis. It is also evident that H₂S is involved in complex signaling pathways and ion channels that inhibit fibrosis development. These findings support the role of H₂S in the treatment of a variety of fibrotic diseases. A randomized controlled trial in fibrosis patients comparing the efficacy of exogenous H₂S and placebo in addition to standard of care can be implemented to validate this further.

Beneficial effects of Oltipraz, nuclear factor - erythroid - 2 - related factor 2 (Nrf2), on renal damage in unilateral ureteral obstruction rat model

Introduction:

We investigated whether Oltipraz (OPZ) attenuated renal fibrosis in a unilateral ureteral obstruction (UUO) rat model.

Materials and Methods:

We randomly divided 32 rats into four groups, each consisting of eight animals as follows: Rats in group 1 underwent a sham operation and received no treatment. Rats in group 2 underwent a sham operation and received OPZ. Rats in group 3 underwent unilateral ureteral ligation and received no treatment. Group 4 rats were subjected to unilateral ureteral ligation plus OPZ administration. Transforming growth factor beta-1 (TGF-β1), E-cadherin, nitric oxide (NO) and hydroxyproline levels were measured. Histopathological and immunohistochemical examinations were carried out.

Results:

TGF-β1, NO and E-cadherin levels in the UUO group were significantly higher than the sham group and these values were significantly different in treated groups compared to the UUO group. In rats treated with UUO + OPZ, despite the presence of mild tubular degeneration and less severe tubular necrosis, glomeruli maintained a better morphology when compared to the UUO group. Expressions of α-SMA in immunohistochemistry showed that the staining positivity decreased in the tubules of the OPZ-treated group.

Conclusions:

While the precise mechanism of action remains unknown, our results demonstrated that OPZ exerted a protective role in the UUO-mediated renal fibrosis rat model highlighting a promising therapeutic potency of Nrf2-activators for alleviating the detrimental effects of unilateral obstruction in kidneys.

Cystathionine γ-Lyase Deficiency Exacerbates CCl4-Induced Acute Hepatitis and Fibrosis in the Mouse Liver

AIMS

The present study examined the role of cystathionine γ-lyase (CSE) in carbon tetrachloride (CCl₄)-induced liver damage.

RESULTS

A CSE gene knock-out and luciferase gene knock-in (KI) mouse model was constructed to study the function of CSE and to trace its expression in living status. CCl₄ or lipopolysaccharide markedly downregulated CSE expression in the liver of mice. CSE-deficient mice showed increased serum alanine aminotransferase and aspartate aminotransferase levels, and liver damage after CCl₄ challenge, whereas albumin and endogenous hydrogen sulfide (H₂S) levels decreased significantly. CSE knockout mice showed increased serum homocysteine levels, upregulation of inflammatory cytokines, and increased autophagy and IκB-α degradation in the liver in response to CCl₄ treatment. The increase in pro-inflammatory cytokines, including tumor necrosis factor-alpha in CSE-deficient mice after CCl₄ challenge, was accompanied by a significant increase in liver tissue hydroxyproline and α-smooth muscle actin and histopathologic changes in the liver. However, H₂S donor pretreatment effectively attenuated most of these imbalances.

INNOVATION

Here, a CSE knock-out and luciferase KI mouse model was established for the first time to study the transcriptional regulation of CSE expression in real time in a non-invasive manner, providing information on the effects and potential mechanisms of CSE on CCl₄-induced liver injury.

CONCLUSION

CSE deficiency increases pro-inflammatory cytokines in the liver and exacerbates acute hepatitis and liver fibrosis by reducing H₂S production from L-cysteine in the liver. The present data suggest the potential of an H₂S donor for the treatment of liver diseases such as toxic hepatitis and fibrosis. Antioxid. Redox Signal. 27, 133-149.

The Role of Hydrogen Sulfide in Renal System

Hydrogen sulfide has gained recognition as the third gaseous signaling molecule after nitric oxide and carbon monoxide. This review surveys the emerging role of H2S in mammalian renal system, with emphasis on both renal physiology and diseases. H2S is produced redundantly by four pathways in kidney, indicating the abundance of this gaseous molecule in the organ. In physiological conditions, H2S was found to regulate the excretory function of the kidney possibly by the inhibitory effect on sodium transporters on renal tubular cells. Likewise, it also influences the release of renin from juxtaglomerular cells and thereby modulates blood pressure. A possible role of H2S as an oxygen sensor has also been discussed, especially at renal medulla. Alternation of H2S level has been implicated in various pathological conditions such as renal ischemia/reperfusion, obstructive nephropathy, diabetic nephropathy, and hypertensive nephropathy. Moreover, H2S donors exhibit broad beneficial effects in renal diseases although a few conflicts need to be resolved. Further research reveals that multiple mechanisms are underlying the protective effects of H2S, including anti-inflammation, anti-oxidation, and anti-apoptosis. In the review, several research directions are also proposed including the role of mitochondrial H2S in renal diseases, H2S delivery to kidney by targeting D-amino acid oxidase/3-mercaptopyruvate sulfurtransferase (DAO/3-MST) pathway, effect of drug-like H2S donors in kidney diseases and understanding the molecular mechanism of H2S. The completion of the studies in these directions will not only improves our understanding of renal H2S functions but may also be critical to translate H2S to be a new therapy for renal diseases.