Upregulation of cystathionine-γ-lyase/hydrogen sulfide pathway underlies the celecoxib counteraction of cyclosporine-induced hypertension and renal insult in rats

Telmisartan ameliorates nephropathy and restores the hippo pathway in rats with metabolic syndrome

The main objective of this study was to determine if the telmisartan-ameliorative effects of metabolic syndrome (MetS)-evoked nephropathy are attributed to the Hippo pathway. A secondary objective was to investigate the potential of vitamin D3 to enhance telmisartan-favourable effects. A diet composed of 24% fat and 3% salt, along with drinking water containing 10% fructose, was administered for 12 weeks to induce MetS. MetS-rats were given telmisartan (5 mg/kg/day), vitamin D3 (10 μg/kg/day) or both by gavage, starting in the sixth week of experimental diet administration. Assessments performed at closure included renal function, histological examination, catalase, malondialdehyde (MDA), nuclear factor kappa-B (NF-κB), interleukin-6 (IL-6), peroxisome proliferator-activated receptor-γ (PPAR-γ), phosphatase and tensin homolog (PTEN), and transforming growth factor-β (TGF-β). Matrix metalloproteinase-9 (MMP-9) immunostaining was conducted. The expression of the Hippo pathway components, as well as that of angiotensin II type 1 and type 2 (AT1 and AT2), receptors was evaluated. Telmisartan attenuated MetS-evoked nephropathy, as demonstrated by improvement of renal function and histological features, enhancement of catalase, reduction of MDA, inflammation (NF-κB, IL-6), and renal fibrosis (increased PPAR-γ and PTEN and reduced MMP-9 and TGF-β). Telmisartan downregulated AT1-receptor, upregulated AT2-receptor and restored the Hippo pathway. Vitamin D3 replicated most of the telmisartan-elicited effects and enhanced the antifibrotic actions of telmisartan. The alleviative effects of telmisartan on MetS-evoked nephropathy may be related to the restoration of the Hippo pathway. The combination of vitamin D3 and telmisartan exerted more favourable effects on metabolic and nephropathic biomarkers compared with either one administered alone.

Cyclooxygenase-2 inhibition prevents renal toxicity but not hypertension during sunitinib treatment

BACKGROUND

Anticancer angiogenesis inhibitors cause hypertension and renal injury. Previously we observed in rats that high-dose aspirin (capable of blocking cyclooxygenase (COX)-1 and-2) was superior to low-dose aspirin (blocking COX-1 only) to prevent these side-effects during treatment with the angiogenesis inhibitor sunitinib, suggesting a role for COX-2. High-dose aspirin additionally prevented the rise in COX-derived prostacyclin (PGI2). Therefore, we studied the preventive effects of selective COX-2 inhibition and the hypothesized contributing role of PGI2 during angiogenesis inhibition.

METHODS

Male WKY rats received vehicle, sunitinib ((SU), 14 mg/kg/day) alone or combined with COX-2 inhibition (celecoxib, 10 mg/kg/day) or a PGI2 analogue (iloprost, 100 μg/kg/day) for 8 days (n = 8-9 per group). Mean arterial pressure (MAP) was measured via radiotelemetry, biochemical measurements were performed via ELISA and vascular function was assessed via wire myography.

RESULTS

SU increased MAP (17±1mmHg versus 3±1mmHg after vehicle on day 4, P < 0.002), which could not be significantly blunted by celecoxib (+12±3mmHg on day 4, P = 0.247), but was temporarily attenuated by iloprost (treatment days 1 + 2 only). Urinary PGI2 (996 ± 112 versus 51 ± 11ng/24h after vehicle, P < 0.001), but not circulating PGI2 increased during SU, which remained unaffected by celecoxib and iloprost. Celecoxib reduced sunitinib-induced albuminuria (0.36 ± 0.05 versus 0.58 ± 0.05mg/24h after SU, P = 0.005). Wire myography demonstrated increased vasoconstriction to endothelin-1 after SU (Emax P = 0.005 versus vehicle), which remained unaffected by celecoxib or iloprost.

CONCLUSION

Selective COX-2 inhibition ameliorates albuminuria during angiogenesis inhibition with sunitinib, which most likely acts independently of PGI2. To combat angiogenesis inhibitor-induced hypertension, dual rather than selective COX-1/2 blockade seems preferential.

Palliative Role of Zamzam Water against Cyclosporine-Induced Nephrotoxicity through Modulating Autophagy and Apoptosis Crosstalk

Cyclosporine (CsA) is considered one of the main components of treatment protocols for organ transplantation owing to its immunosuppressive effect. However, its use is very restricted due to its nephrotoxic effect. ZW is an alkaline fluid rich in various trace elements and has a great ability to stimulate antioxidant processes. This study aimed to investigate the possible mitigating effect of ZW on CsA-induced nephrotoxicity and its underlying mechanisms. Forty rats were allocated into four groups (n = 10): a control group, ZW group, cyclosporine A group (injected subcutaneously (SC) with CsA (20 mg/kg/day)), and cyclosporine A+ Zamzam water group (administered CsA (SC) and ZW as their only drinking water (100 mL/cage/day) for 21 days). Exposure to CsA significantly (p < 0.001) increased the serum creatinine level, lipid peroxidation marker level (malondialdehyde; MDA), and the expression of apoptotic markers procaspase-8, caspase-8, caspase- 9, calpain, cytochrome c, caspas-3, P62, and mTOR in renal tissues. Meanwhile, it markedly decreased (p< 0.001) the autophagic markers (AMPK, ULK-I, ATag5, LC3, and Beclin-1), antiapoptotic Bcl-2, and antioxidant enzymes. Moreover, the administration of CsA caused histological alterations in renal tissues. ZW significantly (p < 0.001) reversed all the changes caused by CsA and conclusively achieved a positive outcome in restraining CsA-induced nephrotoxicity, as indicated by the restoration of the histological architecture, improvement of renal function, inhibition of apoptosis, and enhancement of autophagy via the AMPK/mTOR pathway.

TLRs-JNK/ NF-κB Pathway Underlies the Protective Effect of the Sulfide Salt Against Liver Toxicity

Hydrogen sulfide (H₂S) is an endogenously gas transmitter signaling molecule with known antioxidant, anti-inflammatory, and cytoprotective properties. Although accumulating evidence shows the therapeutic potential of H₂S in various hepatic diseases, its role in cyclophosphamide (CP)-induced hepatotoxicity remains elusive. The present study was undertaken to investigate the impact of endogenous and exogenous H₂S on toll-like receptors (TLRs)-mediated inflammatory response and apoptosis in CP-induced hepatotoxicity. Either an H₂S donor (NaHS (100 μM/kg) or an H2S blocker [dl-propargylglycine (PAG) (30 mg/kg, i. p.)], was administered for 10 days before a single ip injection of CP (200 mg/kg). NaHS attenuated conferred hepatoprotection against CP-induced toxicity, significantly decreasing serum hepatic function tests and improving hepatic histopathology. Additionally, NaHS-treated rats exhibited antioxidant activity in liver tissues compared with the CP group. The upregulated hepatic levels of TLR2/4 and their downstream signaling molecules including c-Jun N-terminal kinase (JNK) and nuclear factor-kappa B (NF-κB) were also suppressed by NaHS protective treatment. NaHS showed anti-inflammatory and antiapoptotic effects; reducing hepatic level tumor necrosis factor-alpha (TNF-α) and caspase-3 expression. Interestingly, the cytotoxic events induced in CP-treated rats were not significantly altered upon the blocking of endogenous H₂S. Taken together, the present study suggested that exogenously applied H₂S rather than the endogenously generated H₂S, displayed a hepatoprotective effect against CP-induced hepatotoxicity that might be mediated by TLRs-JNK/NF-κB pathways.

Quercetin ameliorated remote myocardial injury induced by renal ischemia/reperfusion in rats: Role of Rho-kinase and hydrogen sulfide

AIMS

This study was designated to investigate the means through which quercetin confers its cardioprotective action against remote cardiomyopathy elicited by renal ischemia/reperfusion (I/R). Potential involvement of hydrogen sulfide (H₂S) and its related mechanisms were accentuated herein.

MAIN METHODS

In anesthetized male Wistar rats, renal I/R was induced by bilateral renal pedicles occlusion for 30 min (ischemia) followed by 24 h reperfusion. Quercetin (50 mg/kg, gavage) was administered at 5 h post reperfusion initiation and 2 h before euthanasia. Cystathionine β-synthase (CBS) inhibitor, amino-oxyacetic acid (AOAA; 10 mg/kg, i.p) was given 30 min prior to each quercetin dose.

KEY FINDINGS

Quercetin reversed renal I/R induced derangements; as quercetin administration improved renal function and reversed I/R induced histopathological changes in both myocardium and kidney. Further, quercetin enhanced renal CBS content/activity, while mitigated myocardial cystathionine ɤ-lyase (CSE) content/activity as well as myocardial H₂S. On the other hand, quercetin augmented myocardial nitric oxide (NO), nuclear factor erythroid 2-related factor 2 (Nrf2) and its nuclear trasnslocation, glutamate cysteine ligase (GCL), reduced glutathione (GSH) and peroxiredoxin-2 (Prx2), while further reduced lipid peroxidation measured as malondialdehyde (MDA) as well as nuclear factor-kappa B (NF-κB), caspase-3 content and activity, and Rho-kinase activity.

SIGNIFICANCE

Cardioprotective effects of quercetin may be mediated through regulation of Rho-kinase pathway and H₂S production.

Avocado Seeds Relieve Oxidative Stress-Dependent Nephrotoxicity but Enhance Immunosuppression Induced by Cyclosporine in Rats

Cyclosporine A's (CsA) immunosuppressive effect makes it an ideal drug for organ transplantation. However, CsA's uses are restricted due to its side effects. We investigated the effects of avocado seed (AvS) powder on CsA-induced nephrotoxicity and immunosuppression in rats. The injection of CsA (5 mg/kg, subcutaneously, for 10 days) increased serum levels of creatinine, uric acid, and urea, and the renal levels of the malondialdehyde. It decreased creatinine clearance and the renal activity of antioxidant enzymes (superoxide dismutase, catalase, and glutathione peroxidase) and Na⁺/K⁺ ATPase. The administration of CsA also significantly downregulated the renal expression of interferon-gamma, tumor necrosis factor-alpha, interleukin 1 beta, monocyte chemotactic protein 1, intercellular adhesion molecule-1, and vascular cell adhesion molecule 1 genes, and increased renal DNA damage. Histopathological examination confirmed the biochemical and molecular alterations that accompanied CsA nephrotoxicity. All CsA-induced deleterious effects, except immunosuppression, were ameliorated by feeding rats on a basal diet supplemented with 5% AvS powder for 4 weeks. Importantly, AvS also maximized CsA's immunosuppressive effect. These findings suggest a potential ameliorative effect of AvS on CsA-induced nephrotoxicity, and AvS enhances CsA's immunosuppressive effect. Therefore, AvS might be used in combination with CsA in transplantation treatment to relieve the CsA-induced nephrotoxicity.

Nephroprotective effect of exogenous hydrogen sulfide donor against cyclophosphamide-induced toxicity is mediated by Nrf2/HO-1/NF-κB signaling pathway

AIM

Cyclophosphamide (CP) is an effective anticancer and immunosuppressive agent. However, it induces nephrotoxicity that limits its use. This study explored the effect of H₂S, an important biological signaling molecule with a cytoprotective activity, on CP-induced nephrotoxicity.

METHODS

Male Wistar rats were treated with saline or NaHS (100 μM/kg/day, H₂S donor) or dl-propargylglycine (PAG) (30 mg/kg/day, H₂S blocker) for 10 days before a single i.p injection of CP (200 mg/kg). Then, rats were sacrificed, and renal functions were assessed in serum. Histopathological changes, as well as oxidant defenses, inflammatory and apoptotic markers in the renal tissue, were evaluated.

KEY FINDINGS

Pretreatment with NaHS significantly reduced the urea and creatinine levels that were elevated in CP-intoxicated rats. NaHS increased the expression of the cytoprotective nuclear factor erythroid 2-related factor 2 (Nrf2) and its subsequent antioxidant proteins; heme oxygenase-1 (HO-1), NAD(P) H quinone oxidoreductase 1 (NQO1), reduced glutathione (GSH) and superoxide dismutase (SOD). Moreover, NaHS prohibited the histopathological damage induced by CP. The inhibition of caspase-3 and nuclear factor kappa B (NF-κB) supported the protective role of H₂S against CP-induced kidney damage. On the other hand, blocking endogenous H₂S did not provide a more significant deterioration in CP-induced nephrotoxicity in terms of oxidative stress or inflammatory status.

SIGNIFICANCE

Exogenous H₂S donors exhibited a protective effect against CP-induced nephrotoxicity, which may be mediated via the Nrf2/HO-1/NF-κB signaling pathway. However, endogenous H₂S may be insufficient to protect the cell against the induced oxidative damage. This approach provides a novel target to prevent nephrotoxicity of CP.

Hydrogen Sulfide in Pharmacotherapy, Beyond the Hydrogen Sulfide-Donors

Hydrogen sulfide (H₂S) is one of the important biological mediators involved in physiological and pathological processes in mammals. Recently developed H₂S donors show promising effects against several pathological processes in preclinical and early clinical studies. For example, H₂S donors have been found to be effective in the prevention of gastrointestinal ulcers during anti-inflammatory treatment. Notably, there are well-established medicines used for the treatment of a variety of diseases, whose chemical structure contains sulfur moieties and may release H₂S. Hence, the therapeutic effect of these drugs may be partly the result of the release of H₂S occurring during drug metabolism and/or the effect of these drugs on the production of endogenous hydrogen sulfide. In this work, we review data regarding sulfur drugs commonly used in clinical practice that can support the hypothesis about H₂S-dependent pharmacotherapeutic effects of these drugs.