Sildenafil attenuates renal injury in an experimental model of rat cisplatin-induced nephrotoxicity

A combination of generated hydrogen sulfide and nitric oxide activity has a potentiated protectant effect against cisplatin induced nephrotoxicity

Aim

Hydrogen sulfide and nitric oxide possess cytoprotective activity and in vivo, they are generated from exogenous sodium hydrosulfide and L-arginine respectively. Cisplatin is a major chemotherapeutic agent used to treat cancer and has a high incidence of nephrotoxicity as a side effect. The study aim was to explore the effects of NaHS and L-arginine or their combination on cisplatin induced nephrotoxicity in rats.

Methods

Wistar Kyoto rats were given a single intraperitoneal dose of cisplatin (5 mg/kg) followed either by NaHS (56 μmol/kg, i. p.), L-arginine (1.25 g/L in drinking water) or their combination daily for 28-days. Post-mortem plasma, urine and kidney samples were collected for biochemical assays and histopathological analysis.

Results

Cisplatin decreased body weights and increased urinary output, while plasma creatinine and urea levels were elevated, but sodium and potassium concentrations were diminished. The renal function parameters, blood urea nitrogen and creatinine clearance, were raised and decreased respectively. Regarding markers of reactive oxygen species, plasma total superoxide dismutase was reduced, whereas malondiadehyde was augmented.Cisplatin also diminished plasma and urinary H2S as well as plasma NO, while NaHS and L-arginine counteracted this activity on both redox-active molecules. Cisplatin cotreatment with NaHS, and/or L-arginine exhibited a reversal of all other measured parameters.

Conclusion

In current study, NaHS and L-arginine as monotherapy protected the rats from cisplatin-induced nephrotoxicity but the combination of both worked more effectively suggesting the augmented anti-inflammatory and antioxidative potential of test treatments when administered together.

Ammonium tetrathiomolybdate relieves oxidative stress in cisplatin-induced acute kidney injury via NRF2 signaling pathway

Cisplatin is an efficient chemotherapeutic agent for various solid tumors, but its usage is restricted by nephrotoxicity. A single dose of cisplatin can cause acute kidney injury (AKI), which is characterized by rapid reduction in kidney function. However, the current therapies, such as hydration, are limited. It is vital to develop novel therapeutic reagents that have both anticancer and renoprotective properties. The objective of this study was to determine whether ammonium tetrathiomolybdate (TM), a copper chelator used to treat cancer and disorders of copper metabolism, may offer protection against cisplatin-induced AKI. In this study, we demonstrated that TM treatment had antioxidative effects and mitigated cisplatin-induced AKI both in vivo and in vitro. Mechanically, TM inhibited NRF2 ubiquitination, which activated the NRF2 pathway in HK-2 cells and promoted the expression of target genes. It should be noted that the protective effect conferred by TM against cisplatin was compromised by the knockdown of the NRF2 gene. Furthermore, TM selectively activated the NRF2 pathways in the liver and kidney. The current study provided evidence for additional clinical applications of TM by showing that it activates NRF2 and has a favorable therapeutic impact on cisplatin-induced AKI.

Sildenafil and Kidney Function in Heart Failure with Preserved Ejection Fraction

Key Points

Sildenafil induced an acute effect on eGFR without change in the overall eGFR slope after 24 weeks in a heart failure with preserved ejection fraction (HFpEF) cohort. N -terminal pro–brain natriuretic peptide levels and baseline diuretic use were most strongly associated with eGFR decline in this HFpEF cohort. Long-term studies are required to determine sildenafil's influence on kidney function and outcomes in HFpEF.

Background

CKD worsens the prognosis for people with heart failure with preserved ejection fraction (HFpEF). In the Phosphodiesterase-5 Inhibition to Improve Clinical Status and Exercise Capacity in Diastolic HFpEF (RELAX) trial, sildenafil decreased eGFR compared with placebo despite favorable kidney effects in preclinical models. Since acute eGFR decline precedes long-term kidney benefits for select medications, we assessed the influence of sildenafil on acute and chronic eGFR slopes.

Methods

The RELAX trial randomized 216 participants to placebo or sildenafil and assessed 24-week changes in cardiopulmonary exercise testing, cardiovascular imaging, and laboratory data. We applied linear mixed modeling to calculate the total, acute (0–12 weeks), and chronic (3–24 weeks) eGFR slopes by treatment. Using regression modeling, we assessed respective associations between eGFR slope and baseline data and clinical end points. We repeated the analyses using a binary outcome on the basis of a substantial (≥20%) decline in eGFR.

Results

The mean baseline eGFR was 60.8 ml/min per 1.73 m2, and the mean eGFR slope during follow-up was −3.21 ml/min per 1.73 m2 per year. Sildenafil did not alter total eGFR slope compared with placebo (difference +0.47 ml/min per 1.73 m2 per year, 95% confidence interval [CI], −6.63 to 7.57 ml/min per 1.73 m2 per year). Sildenafil users tended to experience a more negative acute eGFR slope (difference −3.15 ml/min per 1.73 m2 per year) and more positive chronic slope (+2.06 ml/min per 1.73 m2 per year) compared with placebo, but neither difference reached statistical significance. Baseline N -terminal pro–B-type natriuretic peptide and loop diuretic use were associated with worse eGFR trajectory regardless of treatment. Substantial eGFR decline was associated with increase in endothelin-1 and a greater risk of hospitalization or death (HR, 2.34, 95% CI, 1.21 to 4.53, P =0.01).

Conclusions

Sildenafil induced an acute effect on eGFR without change in the overall eGFR slope after 24 weeks in an HFpEF cohort, suggesting lack of long-term risk related to early reduction in eGFR after initiating treatment. Long-term studies are needed to determine the effect of sildenafil on kidney function in HFpEF.

The efficacy of PDE5 inhibitors in diabetic patients

BACKGROUND

Phosphodiesterase 5 inhibitors (PDE5i), since their introduction in the late 1990s, have proven their efficacy in treating several conditions, predominantly pulmonary hypertension and erectile dysfunction where they remain the first-line therapeutic option. However, in the recent years, growing evidence from both animal and human studies has emerged to suggest the additional benefits of PDE5i in cardiovascular and metabolic disorders. This is of specific interest to the diabetes population where prevalent cardiovascular disease and metabolic dysregulation significantly contribute to the increased morbidity and mortality.

OBJECTIVES

To examine the available data on the non-standard, pleiotropic effects of PDE5i in patients with diabetes mellitus.

MATERIALS AND METHODS

The review of the published background research, preclinical studies and clinical trials.

RESULTS

In human studies, PDE5 inhibition appeared to be associated with reduced cardiovascular mortality and overall improved clinical outcomes in those with established cardiovascular disease. PDE5i were also consistently found to reduce albuminuria in subjects with diabetic nephropathy. Furthermore, animal data suggest a plausible effect of this group of medication on sensory function and neuropathic symptoms in diabetic neuropathy as well as improved wound healing. A decrease in insulin resistance and augmentation of beta cell function seen in preclinical studies has not been consistently demonstrated in human trials.

DISCUSSION AND CONCLUSION

In animal models, PDE5 inhibition appears to decrease oxidative stress and reduce some of the micro- and macrovascular complications associated with diabetes. However, data from human trials are limited and largely inconsistent, highlighting the need for adequately powered, randomised-controlled trials in diabetic cohorts in order to fully assess the benefits of PDE5i in this group of patients.

Electric field-directed migration of mesenchymal stem cells enhances their therapeutic potential on cisplatin-induced acute nephrotoxicity in rats

Cisplatin is widely used as an anti-neoplastic agent but is limited by its nephrotoxicity. The use of mesenchymal stem cells (MSCs) for the management of acute kidney injury (AKI) represents a new era in treatment but effective homing of administered cells is needed. This study aimed to investigate the effect of bone marrow-derived mesenchymal stem cells (BM-MSCs) on cisplatin-induced AKI in rats after directed migration by electric field (EF). Forty-eight adult male albino rats were equally classified into four groups: control, cisplatin-treated, cisplatin plus BM-MSCs, and cisplatin plus BM-MSCs exposed to EF. Serum levels of IL-10 and TNF-α were measured by ELISA. Quantitative real-time PCR analysis for gene expression of Bcl2, Bax, caspase-3, and caspase-8 was measured. Hematoxylin and eosin (H&E) staining, periodic acid Schiff staining, and immunohistochemical analysis were also done. MSC-treated groups showed improvement of kidney function; increased serum levels of IL-10 and decreased levels of TNF-α; and increased mRNA expression of Bcl2 and decreased expression of Bax, caspase-3, and caspase-8 proteins comparable to the cisplatin-injured group. EF application increased MSCs homing with significant decrease in serum urea level and caspase-3 gene expression together with significant increase in Bcl2 expression than occurred in the MSCs group. Restoration of normal kidney histomorphology with significant decrease in immunohistochemical expression of caspase-3 protein was observed in the BM-MSCs plus EF group compared to the BM-MSCs group. EF stimulation enhanced the MSCs homing and improved their therapeutic potential on acute cisplatin nephrotoxicity.

7-hydroxycoumarin modulates Nrf2/HO-1 and microRNA-34a/SIRT1 signaling and prevents cisplatin-induced oxidative stress, inflammation, and kidney injury in rats

The kidneys are vulnerable to toxicity and acute kidney injury (AKI) is the main adverse effect associated with the clinical use of the chemotherapeutic agent cisplatin (CIS). Oxidative stress and inflammation are implicated in CIS nephrotoxicity. In this study, the effect of the antioxidant 7-hydroxycoumarin (7-HC) against CIS-induced renal intoxication was evaluated. Rats received 7-HC (25, 50, and 100 mg/kg) orally for 14 days and CIS (7 mg/kg) at day 15, and samples were collected 3 days after CIS administration. CIS increased serum urea, creatinine and kidney injury molecule (Kim)-1, caused multiple histopathological changes and increased renal reactive oxygen species (ROS), malondialdehyde (MDA), nitric oxide (NO), NF-κB p65, iNOS, and pro-inflammatory cytokines. 7-HC dose-dependently prevented kidney dysfunction and tissue injury and suppressed ROS and inflammatory mediators. 7-HC boosted renal antioxidants and Bcl-2 while decreased Bax and caspase-3 expression in CIS-administered rats. In addition, 7-HC downregulated Keap-1 and microRNA-34a and upregulated Nrf2, NQO-1, HO-1, and SIRT1. Molecular docking revealed the binding affinity of 7-HC towards NF-κB, Keap-1, and SIRT1. In Conclusion, 7-HC prevented CIS nephrotoxicity by attenuating tissue injury, oxidative stress, inflammation, and apoptotic cell death. The protective efficacy of 7-HC was associated with inhibiting NF-κB and Keap-1, and modulating Nrf2/HO-1 and microRNA34a/Sirt1 signaling.

Sildenafil, a Type-5 Phosphodiesterase Inhibitor, Fails to Reverse Myeloid-Derived Suppressor Cell-Mediated T Cell Suppression in Cells Isolated From Tuberculosis Patients

Successful TB treatment is hampered by increasing resistance to the two most effective first-line anti-TB drugs, namely isoniazid and rifampicin, thus innovative therapies focused on host processes, termed host-directed therapies (HDTs), are promising novel approaches for increasing treatment efficacy without inducing drug resistance. We assessed the ability of Sildenafil, a type-5 phosphodiesterase inhibitor, as a repurposed compound, to serve as HDT target, by counteracting the suppressive effects of myeloid-derived suppressor cells (MDSC) obtained from active TB cases on T-cell responsiveness. We confirm that MDSC suppress non-specific T-cell activation. We also show that Sildenafil treatment fails to reverse the MDSC-mediated suppression of T-cell functions measured here, namely activation and proliferation. The impact of Sildenafil treatment on improved immunity, using the concentration tested here, is likely to be minimal, but further identification and development of MDSC-targeting TB host-directed therapies are warranted.

FKBP51, AmotL2 and IQGAP1 Involvement in Cilastatin Prevention of Cisplatin-Induced Tubular Nephrotoxicity in Rats

The immunophilin FKBP51, the angiomotin AmotL2, and the scaffoldin IQGAP1 are overexpressed in many types of cancer, with the highest increase in leucocytes from patients undergoing oxaliplatin chemotherapy. Inflammation is involved in the pathogenesis of nephrotoxicity induced by platinum analogs. Cilastatin prevents renal damage caused by cisplatin. This functional and confocal microscopy study shows the renal focal-segmental expression of TNFα after cisplatin administration in rats, predominantly of tubular localization and mostly prevented by co-administration of cilastatin. FKBP51, AmotL2 and IQGAP1 protein expression increases slightly with cilastatin administration and to a much higher extent with cisplatin, in a cellular- and subcellular-specific manner. Kidney tubule cells expressing FKBP51 show either very low or no expression of TNFα, while cells expressing TNFα have low levels of FKBP51. AmotL2 and TNFα seem to colocalize and their expression is increased in tubular cells. IQGAP1 fluorescence increases with cilastatin, cisplatin and joint cilastatin-cisplatin treatment, and does not correlate with TNFα expression or localization. These data suggest a role for FKBP51, AmotL2 and IQGAP1 in cisplatin toxicity in kidney tubules and in the protective effect of cilastatin through inhibition of dehydropeptidase-I.

Protective effects of sildenafil administration on chemotherapeutic-induced ovarian damage in rats

Agents to reduce the gonadotoxic effects of chemotherapeutics are still under investigation. In this context, we aimed to investigate the protective effect of sildenafil against chemotherapeutic-induced gonadotoxicity in a rat model. A total of 62 female rats were divided into eight groups as control, sildenafil (1.4 mg/kg, orally), doxorubicin (3 mg/kg, i.p.), cisplatin (5 mg/kg, i.p.), cyclophosphamide (200 mg/kg, i.p.), doxorubicin+sildenafil, cisplatin+sildenafil, and cyclophosphamide+sildenafil (1.4 mg/kg orally sildenafil in addition to the same dose of chemotherapeutics). The groups were compared in terms of follicle count, ovarian size, and anti-müllerian hormone (AMH) levels. Use of sildenafil with cyclophosphamide was effective only in preserving primary follicle count (p = 0.026) and had no significant change in the secondary follicle count, ovarian size, or AMH level. Adding sildenafil to cisplatin had a significant protective effect on primary follicle count (p = 0.011), secondary follicle count (p = 0.009), and ovarian size (p = 0.001), but this effect could not be demonstrated at AMH level. Sildenafil was not effective on any parameter in the doxorubicin group. Sildenafil may be effective in reducing the gonadotoxicity associated with the use of cisplatin and cyclophosphamide.

Phosphodiesterase-5 inhibitor sildenafil attenuates kidney injury induced by Bothrops alternatus snake venom

Acute kidney injury pathogenesis in envenoming by snakes is multifactorial and involves immunologic reactions, hemodynamic disturbances, and direct nephrotoxicity. Sildenafil (SFC), a phosphodiesterase 5 inhibitor, has been reported to protect against pathological kidney changes.

OBJECTIVE

This study aimed to investigate the protective effect of sildenafil against Bothrops alternatus snake venom (BaV)-induced nephrotoxicity.

METHODS

Kidneys from Wistar rats (n = 6, weighing 260-300 g) were isolated and divided into four groups: (1) perfused with a modified Krebs-Henseleit solution (MKHS) containing 6 g% of bovine serum albumin; (2) administered 3 μg/mL SFC; (3) perfused with 3 μg/mL BaV; and (4) administered SFC + BaV, both at 3 μg/mL. Subsequently, the perfusion pressure (PP), renal vascular resistance (RVR), urinary flow (UF), glomerular filtration rate (GFR), and percentage of electrolyte tubular sodium and chloride transport (%TNa⁺, %TCl^-, respectively) were evaluated. The cyclic guanosine monophosphate (cGMP) levels were analyzed in the perfusate, and the kidneys were removed to perform oxidative stress and histopathological analyses.

RESULTS

All renal parameters evaluated were reduced with BaV. In the SFC + BaV group, SFC restored PP to normal values and promoted a significant increase in %TNa⁺ and %TCl^-. cGMP levels were increased in the SFC + BaV group. The oxidative stress biomarkers, malondialdehyde (MDA) and glutathione (GSH), were reduced by BaV. In the SFC + BaV group, a decrease in MDA without an increase in GSH was observed. These findings were confirmed by histological analysis, which showed improvement mainly in tubulis.

CONCLUSION

Our data suggest the involvement of phosphodiesterase-5 and cGMP in BaV-induced nephrotoxicity since its effects were attenuated by the administration of SFC.

Sildenafil in Combination Therapy against Cancer: A Literature Review

The concepts of drug repurposing and Sildenafil or blue pill are tightly linked over the years. Indeed, in addition to its initial clinical application as an anti-hypertensive drug in the pulmonary system, Sildenafil is also known for its beneficial effects in erectile dysfunction. Moreover, evidence has been accumulated to support its value in anti-cancer therapy, either alone or in combination with other clinically efficient chemotherapy drugs. In this review, we focused on the old and recent in vitro and in vivo studies demonstrating the cellular and molecular rationale for the application of Sildenafil in combination therapy in various types of cancer. We emphasized on the different molecular targets as well as the different signaling pathways involved in cancer cells. The pro-apoptotic effect of Sildenafil through nitric oxide (NO)/ phosphodiesterase type 5 (PDE5)-dependent manner seems to be one of the most common mechanisms. However, the activation of autophagy, as well as the modulation of the anti-tumor immunity, constitutes the other pathways triggered by Sildenafil. Overall, the studies converged to reveal the complexity of the anti-cancer potential of Sildenafil. Thus, through our review, we aimed to present an updated and simplified picture of such repurposing of Sildenafil in the field of oncology.

Sildenafil beyond erectile dysfunction and pulmonary arterial hypertension: Thinking about new indications

Sildenafil, approved two decades ago, is the inhibitor of phosphodiesterase 5 (PDE5). First of all, it was designated for angina pectoris, but soon it showed a wonderful efficacy in erectile dysfunction (ED) and then pulmonary arterial hypertension (PAH). Due to the distribution of phosphodiesterase (PDE) in almost all organs, maybe it effects other diseases. Hence, a great number of investigations began to understand the role of PDEi in different organs. Preliminary research on sildenafil in cell culture and animal models has yielded promising results. Soon, a greater number of animal researches and clinical trials joined them. The results disclosed sildenafil can have beneficial effects in each organ such as heart, liver, kidney, brain, and intestines. Furthermore, it has significantly improved the prognosis of organ ischemia in various animal models. Clinical trials in several diseases, such as recurrent spontaneous miscarriage, fatty liver disease, bronchopulmonary dysplasia (BPD), heart failure, and premature ejaculation (PE) brought promising results. Although some clinical trials are available on the effects of sildenafil on various diseases, further studies on humans are needed to consolidate the ultimate effects of sildenafil. The aim of this review was to describe the effects of sildenafil on each organ and explain its mechanisms of action. Further, other PDE inhibitors such as tadalafil and vardenafil have been briefly discussed in parts of this review.

Current Concepts on the Reno-Protective Effects of Phosphodiesterase 5 Inhibitors in Acute Kidney Injury: Systematic Search and Review

Acute kidney injury (AKI) is associated with increased morbidity, prolonged hospitalization, and mortality, especially in high risk patients. Phosphodiesterase 5 inhibitors (PDE5Is), currently available as first-line therapy of erectile dysfunction in humans, have shown a beneficial potential of reno-protection through various reno-protective mechanisms. The aim of this work is to provide a comprehensive overview of the available literature on the reno-protective properties of PDE5Is in the various forms of AKI. Medline was systematically searched from 1946 to November 2019 to detect all relevant animal and human studies in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) statement. In total, 83 studies were included for qualitative synthesis. Sildenafil is the most widely investigated compound (42 studies), followed by tadalafil (20 studies), icariin (10 studies), vardenafil (7 studies), zaprinast (4 studies), and udenafil (2 studies). Even though data are limited, especially in humans with inconclusive or negative results of only two clinically relevant studies available at present, the results of animal studies are promising. The reno-protective action of PDE5Is was evident in the vast majority of studies, independently of the AKI type and the agent applied. PDE5Is appear to improve the renal functional/histopathological alternations of AKI through various mechanisms, mainly by affecting regional hemodynamics, cell expression, and mitochondrial response to oxidative stress and inflammation.

Myeloid-Derived Suppressor Cells as Target of Phosphodiesterase-5 Inhibitors in Host-Directed Therapeutics for Tuberculosis

Resistance toward current and new classes of anti-tuberculosis (anti-TB) antibiotics are rapidly emerging; thus, innovative therapies focused on host processes, termed host-directed therapies (HDTs), are promising novel approaches for shortening therapy regimens without inducing drug resistance. Development of new TB drugs is lengthy and expensive, and success is not guaranteed; thus, alternatives are needed. Repurposed drugs have already passed Food and Drug Administration (FDA) as well as European Medicines Agency (EMA) safety requirements and may only need to prove efficacy against Mycobacterium tuberculosis (M.tb). Phosphodiesterases (PDEs) hydrolyze the catalytic breakdown of both cyclic adenosine monophosphate (cAMP) and cyclic guanosine monophosphate (cGMP) to their inactive mononucleotides. Advances in molecular pharmacology have identified 11 PDE families; and the success of sildenafil, a PDE-5 selective inhibitor (PDE-5i), in treating pulmonary hypertension and erectile dysfunction has invigorated research into the therapeutic potential of selective PDE inhibitors in other conditions. Myeloid-derived suppressor cells (MDSCs) suppress anti-TB T-cell responses, likely contributing to TB disease progression. PDE-5i increases cGMP within MDSC resulting in the downregulation of arginase-1 (ARG1) and nitric oxide synthase 2 (NOS2), reducing MDSC's suppressive potential. The effect of this reduction decreases MDSC-induced T-cell-suppressive mechanisms. This review highlights the possibility of HDT targeting of MDSC, using a PDE-5i in combination with the current TB regimen, resulting in improved TB treatment efficacy.

Disulfiram and Its Copper Chelate Attenuate Cisplatin-Induced Acute Nephrotoxicity in Rats Via Reduction of Oxidative Stress and Inflammation

The use of cisplatin (CP) in chemotherapy of resistant cancers is limited due to its dose-dependent nephrotoxicity. Disulfiram (DSF), the aversion therapy for alcoholism, has recently emerged as an anticancer and chemopreventive agent. Its anticancer activity is potentiated in the presence of copper. However, such use of copper leads to several adverse effects. In the present study, the protective effect of DSF and its copper chelate (Cu-DEDC) against CP-induced nephrotoxicity in rats was evaluated. Nephrotoxicity was induced by a single intraperitoneal injection of CP (5 mg/kg). The treatment groups included control (vehicle treated), CP (CP-treated), CP + DSF (CP followed by DSF), CP + DSF + Cu (CP followed by DSF and CuCl₂), CP + Cu-DEDC (CP followed by Cu-DEDC), and CP + AMF (amifostine pre-treated and CP-treated). The DSF, Cu-DEDC, and CuCl₂ were administered orally at 50 mM/kg/day dose for 5 days post CP injection. AMF served as a standard chemo protectant, administered intravenously 30 min prior to CP. The markers of oxidative stress, inflammation, and kidney function estimated on the 6th day revealed that both DSF and Cu-DEDC significantly attenuated the CP-induced rise in the serum/urine creatinine and blood urea nitrogen (BUN). The CP-induced rise in serum alkaline phosphatase (ALPase) was reversed by these drugs. Both drugs reduced the levels of malondialdehyde and nitric oxide (NO) in kidney tissues. These drugs reversed CP-induced depletion of SOD, catalase, and GSH in the kidneys. There was a significant reduction in the CP-induced TNF-α and IL-1β production along with prevention of histological alterations. Above observations indicate that DSF and Cu-DEDC may have significance as adjuvants to protect against CP-induced nephrotoxicity.

Protective effects of zingerone on cisplatin-induced nephrotoxicity in female rats

Zingerone (ZO), one of the active components of ginger (Zingiber officinale), is a phenolic alkanone with antioxidant, antiapoptotic, and anti-inflammatory properties. Cisplatin (CP) is a widely used chemotherapeutic drug for solid tumors, but its therapeutic use is limited due to dose-dependent nephrotoxicity. In the present study, we investigated the ameliorative effect of ZO against CP-induced nephrotoxicity. Intraperitoneal administration of single-dose CP (7 mg/kg body weight) on the first day enhanced kidney lipid peroxidation and reduced antioxidant enzyme activities such as catalase (CAT), superoxide dismutase (SOD), glutathione peroxidase (GPx), and glutathione (GSH). CP increased serum urea and creatinine levels and disrupted histological integrity while causing a decrease aquaporin 1 (AQP1) level in the kidney tissues. CP induced inflammatory responses by elevating the levels of tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), interleukin-6 (IL-6), interleukin-33 (IL-33) and nuclear factor kappa B (NF-κB), and activities of inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2). Moreover, it also caused oxidative DNA damage and activation of apoptotic pathway by increasing of 8-hydroxy-2'-deoxyguanosine (8-OHdG), p53, cysteine aspartate-specific protease-3 (caspase-3), and Bcl-2-associated x protein (bax) while decreasing B cell lymphoma-2 (Bcl-2). However, treatment with ZO at a dose of 25 and 50 mg/kg b.wt. for 7 days significantly decreased oxidative stress, apoptosis, inflammation, and histopathological alterations while increased AQP1 levels in the kidney tissue. The results of the current study suggested that ZO as an effective natural product attenuates CP-induced nephrotoxicity.

β-hydroxybutyrate attenuates renal ischemia-reperfusion injury through its anti-pyroptotic effects

Ketone bodies including β-hydroxybutyrate (β-OHB) have been shown to protect against ischemic tissue injury when present at low concentrations. We evaluated the impact of β-OHB on renal ischemia/reperfusion injury (IRI). Mice were treated with a continuous infusion of β-OHB using an osmotic mini-pump before and after IRI. We also tested the effects of increasing endogenous serum β-OHB levels by fasting. Renal IRI was attenuated by β-OHB treatment compared to saline control, with similar results in the fasting condition. β-OHB treatment reduced the number of terminal deoxynucleotidyl transferase-mediated dUTP nick end-labeling (TUNEL)-positive cells and increased expression of forkhead transcription factor O3 (FOXO3), an upstream regulator of pyroptosis. Although β-OHB treatment did not impact markers of apoptosis, it decreased the expression of caspase-1 and proinflammatory cytokines, indicating that β-OHB blocked pyroptosis. In a human proximal tubular cell line exposed to hypoxia and reoxygenation, β-OHB reduced cell death in a FOXO3-dependent fashion. Histone acetylation was decreased in kidneys exposed to IRI and in proximal tubular cells exposed to hypoxia and reoxygenation, and this effect was ameliorated by β-OHB through the inactivation of histone deacetylases. In vitro, β-OHB treatment restored histone acetylation at the FOXO3 promoter. Consistent with epigenetic molecular effects, the renoprotective effects of β-OHB were still observed when the continuous infusion was stopped at the time of IRI. Thus, β-OHB attenuates renal IRI through anti-pyroptotic effects, likely mediated by an epigenetic effect on FOXO3 expression.

Effect of combination sildenafil and gemfibrozil on cisplatin-induced nephrotoxicity; role of heme oxygenase-1

Background/aim: Cisplatin-induced nephrotoxicity in large proportion of patients. The aim of this work is to clarify the effect of combination of sildenafil and gemfibrozil on cisplatin-induced nephrotoxicity either before or after cisplatin treatment and determination of nephrotoxicity predictors among the measured tissue markers.

Methods: Thirty two adult male albino rats were divided into four equal groups (G) GI control, GII received cisplatin, GIII received sildenafil and gemfibrozil before cisplatin, GIV received sildenafil and gemfibrozil after cisplatin. Creatinine and urea were measured and animals were sacrificed and kidney was taken for histopathology. The following tissue markers were measured, heme oxygenase-1 (HO-1) activity, reduced glutathione, quantitative (real-time polymerase chain reaction) RT-PCR for gene expression of tumor necrosis factor alpha (TNF-α) and endothelial nitric oxide synthase (ENOS) level.

Results: GII developed AKI demonstrated by significantly high urea and creatinine and severe diffuse (80–90%) tubular necrosis. TNF-α was highly and significantly elevated while the rest of tissue markers were significantly reduced in GI1 compared to other groups. GIV showed better results compared to GIII. There was a significant positive correlation between creatinine and TNF-α when combining GI and GII while there were significant negative correlation between creatinine and other tissue markers in same groups. Linear regression analysis demonstrated that HO-1 was the independent predictor of AKI demonstrated by elevated creatinine among GI and GII.

Conclusions: Combination of sildenafil and gemfibrozil can be used in treatment of cisplatin-induced nephrotoxicity. HO-1 is a promising target for prevention and/or treatment of cisplatin-induced nephrotoxicity.

Cisplatin-induced renal inflammation is ameliorated by cilastatin nephroprotection

Background

Cisplatin is a potent chemotherapeutic drug whose nephrotoxic effect is a major complication and a dose-limiting factor for antitumoral therapy. There is much evidence that inflammation contributes to the pathogenesis of cisplatin-induced nephrotoxicity. We found that cilastatin, a renal dehydropeptidase-I inhibitor, has protective effects in vitro and in vivo against cisplatin-induced renal damage by inhibiting apoptosis and oxidation. Here, we investigated the potential use of cilastatin to protect against cisplatin-induced kidney injury and inflammation in rats.

Methods

Male Wistar rats were divided into four groups: control, cilastatin-control, cisplatin and cilastatin-cisplatin. Nephrotoxicity was assessed 5 days after administration of cisplatin based on blood urea nitrogen, creatinine, glomerular filtration rate (GFR), kidney injury molecule (KIM)-1 and renal morphology. Inflammation was measured using the electrophoretic mobility shift assay, immunohistochemical studies and evaluation of inflammatory mediators.

Results

Compared with the control rats, cisplatin-administered rats were affected by significant proximal tubule damage, decreased GFR, increased production of inflammatory mediators and elevations in urea, creatinine and tissue KIM-1 levels. Cilastatin prevented these changes in renal function and ameliorated histological damage in cisplatin-administered animals. Cilastatin also reduced pro-inflammatory cytokine levels, activation of nuclear factor-κB and CD68-positive cell concentrations.

Conclusions

Cilastatin reduces cisplatin-induced nephrotoxicity, which is associated with decreased inflammation in vivo. Although the exact role of decreased inflammation in nephroprotection has not been fully elucidated, treatment with cilastatin could be a novel strategy for the prevention of cisplatin-induced acute kidney injury.

Phosphodiesterase type 5 and cancers: progress and challenges

Cancers are an extraordinarily heterogeneous collection of diseases with distinct genetic profiles and biological features that directly influence response patterns to various treatment strategies as well as clinical outcomes. Nevertheless, our growing understanding of cancer cell biology and tumor progression is gradually leading towards rational, tailored medical treatments designed to destroy cancer cells by exploiting the unique cellular pathways that distinguish them from normal healthy counterparts. Recently, inhibition of the activity of phosphodiesterase type 5 (PDE5) is emerging as a promising approach to restore normal intracellular cyclic guanosine monophosphate (cGMP) signalling, and thereby resulting into the activation of various downstream molecules to inhibit proliferation, motility and invasion of certain cancer cells. In this review, we present an overview of the experimental and clinical evidences highlighting the role of PDE5 in the pathogenesis and prevention of various malignancies. Current data are still not sufficient to draw conclusive statements for cancer patient management, but could provide further rational for testing PDE5-targeting drugs as anticancer agents in clinical settings.

Nephroprotective Effects of Saponins from Leaves of Panax quinquefolius against Cisplatin-Induced Acute Kidney Injury

Although cisplatin is an anticancer drug that has activity against malignant tumor, it often causes nephrotoxicity. Previous reports have confirmed that the saponins from the leaves of P. quinquefolium (PQS) exerted many pharmacological activities. However, the renoprotective effects of PQS were still unknown. The purpose of the present research was to discuss renoprotective effect of PQS in a mouse model of cisplatin-induced acute kidney injury (AKI). The levels of blood urea nitrogen (BUN) and serum creatinine (CRE) were evidently increased in cisplatin-intoxicated mice, which were reversed by PQS. Renal oxidative stress, evidenced by increased malondialdehyde (MDA) level and decline of glutathione (GSH) and superoxide dismutase (SOD) activities, was significantly alleviated by PQS pretreatment. The suppression of inflammatory response by PQS was realized through the decrease the mRNA expression levels of tumor necrosis factor-α (TNF-α) and interleukin-1β (IL-1β) in kidney tissues, which were measured by quantitative real-time polymerase chain reaction (qRT-PCR). Simultaneously, the overexpression of cytochrome P450 E1 (CYP2E1) and heme oxygenase-1 (HO-1) were attenuated by PQS. Furthermore, the effects of Western blotting demonstrated that PQS administration significantly suppressed the protein expression levels of nicotinamide adenine dinucleotide phosphate oxidase type 4 (Nox4), cleaved Caspase-3, cleaved Caspase-9, Bax, nuclear factor-κB (NF-κB), cyclooxygenase-2 (COX-2), and inducible nitric oxide synthase (iNOS), suggesting the inhibition of apoptosis and inflammation response. Overall, PQS may possess protective effects in cisplatin-induced AKI through suppression of oxidative stress, inflammation and apoptosis.

Nafamostat Mesilate Attenuates Ischemia-Reperfusion-Induced Renal Injury

BACKGROUND

It has been reported that nafamostat mesilate (NM) inhibits inflammatory injury via inhibition of complement activation in ischemic heart, liver, and intestine. However, it is unclear if NM also inhibits apoptosis in ischemia-reperfusion (IR)-injured kidney. We therefore investigated whether NM attenuates IR renal injury that involves inhibition of apoptosis.

METHODS

HK-2 cells and male C57BL/6 mice were used for this study. C57Bl/6 mice were divided into 4 groups: sham, NM (2 mg/kg) + sham, IR injury (IR injury; reperfusion 27 minutes after clamping of both the renal artery and vein), and NM + IR injury. Kidneys were harvested 24 hours after IR injury, and functional and molecular parameters were evaluated. For in vitro studies, HK-2 cells were incubated for 6 hours with mineral paraffin oil to induce hypoxic injury, and then treated with various doses of NM to evaluate the antiapoptotic effects.

RESULTS

Blood urea nitrogen, serum creatinine levels, and renal tissue injury scores in NM + IR-injured mice were significantly lower than those of control IR mice (all P < .01). NM significantly improved cell survival in hypoxic HK-2 cells (P < .01), significantly decreased renal Bax expression (P < .05), and increased renal Bcl-2 protein levels in IR kidneys and hypoxic HK-2 cells compared with those of the sham and control groups. The numbers of terminal deoxynucleotide transferase-mediated dUTP nick-end labeling- and 8-oxo-2'-deoxyguanosine-positive cells were significantly lower in NM + IR-injured kidneys compared with those in control IR-injured mice (P < .05); NM treatment decreased the expression of inducible and endothelial nitric oxide synthase in IR-injured mice (P < .05).

CONCLUSIONS

NM ameliorates IR renal injury via inhibition of apoptosis by, at least in part, lowering nitric oxide overproduction, reducing Bax, and increasing Bcl-2.

Ginsenoside Rg5 Ameliorates Cisplatin-Induced Nephrotoxicity in Mice through Inhibition of Inflammation, Oxidative Stress, and Apoptosis

Although cisplatin is an effective anti-cancer agent that is widely used for treating various types of malignant solid tumors, the nephrotoxicity induced by cisplatin severely limits its clinical application. The present study was designed to explore the potential protective effect of ginsenoside Rg5, a rare ginsenoside generated during steaming ginseng, on cisplatin-induced nephrotoxicity in a mouse experimental model. The possible mechanisms underlying this nephroprotective effect were also investigated for the first time. Rg5 was given at doses of 10 and 20 mg/kg for 10 consecutive days. On Day 7, a single nephrotoxic dose of cisplatin (25 mg/kg) was injected to mice. Cisplatin administration resulted in renal dysfunction as evidenced by increase in serum creatinine (CRE) and blood urea nitrogen (BUN) levels. In addition, cisplatin increased the level of malondialdehyde (MDA) and 4-hydroxynonenal (4-HNE), the makers of lipid peroxidation, and depleted glutathione (GSH) content and superoxide dismutase (SOD) activity in renal tissues. These effects were associated with the significantly increased levels of cytochrome P450 E1 (CYP2E1), 4-hydroxynonenal (4-HNE), tumor necrosis factor (TNF)-α, interleukin (IL)-1β, nuclear factor-kappa B (NF-κB) p65, and cyclooxygenase-2 (COX-2) in renal tissues. However, pretreatment with ginsenoside Rg5 significantly attenuated the renal dysfunction, oxidative stress and inflammation response induced by cisplatin. Furthermore, ginsenoside Rg5 supplementation inhibited activation of apoptotic pathways through increasing Bcl-2 and decreasing Bax expression levels. Histopathological examination further confirmed the nephroprotective effect of Rg5. Collectively, these results clearly suggest that Rg5-mediated alleviation of cisplatin-induced nephrotoxicity may be related to its anti-oxidant, anti-apoptotic and anti-inflammatory effects.

The role of cGMP and its signaling pathways in kidney disease

Cyclic nucleotide signal transduction pathways are an emerging research field in kidney disease. Activated cell surface receptors transduce their signals via intracellular second messengers such as cAMP and cGMP. There is increasing evidence that regulation of the cGMP-cGMP-dependent protein kinase 1-phosphodiesterase (cGMP-cGK1-PDE) signaling pathway may be renoprotective. Selective PDE5 inhibitors have shown potential in treating kidney fibrosis in patients with chronic kidney disease (CKD), via their downstream signaling, and these inhibitors also have known activity as antithrombotic and anticancer agents. This review gives an outline of the cGMP-cGK1-PDE signaling pathways and details the downstream signaling and regulatory functions that are modulated by cGK1 and PDE inhibitors with regard to antifibrotic, antithrombotic, and antitumor activity. Current evidence that supports the renoprotective effects of regulating cGMP-cGK1-PDE signaling is also summarized. Finally, the effects of icariin, a natural plant extract with PDE5 inhibitory function, are discussed. We conclude that regulation of cGMP-cGK1-PDE signaling might provide novel, therapeutic strategies for the worsening global public health problem of CKD.

Dapagliflozin, SGLT2 Inhibitor, Attenuates Renal Ischemia-Reperfusion Injury

Dapagliflozin, a new type of drug used to treat diabetes mellitus (DM), is a sodium/glucose cotransporter 2 (SGLT2) inhibitor. Although some studies showed that SGLT2 inhibition attenuated reactive oxygen generation in diabetic kidney the role of SGLT2 inhibition is unknown. We evaluated whether SLT2 inhibition has renoprotective effects in ischemia-reperfusion (IR) models. We evaluated whether dapagliflozin reduces renal damage in IR mice model. In addition, hypoxic HK2 cells were treated with or without SGLT2 inhibitor to investigate cell survival, the apoptosis signal pathway, and the induction of hypoxia-inducible factor 1 (HIF1) and associated proteins. Dapagliflozin improved renal function. Dapagliflozin reduced renal expression of Bax, renal tubule injury and TUNEL-positive cells and increased renal expression of HIF1 in IR-injured mice. HIF1 inhibition by albendazole negated the renoprotective effects of dapagliflozin treatment in IR-injured mice. In vitro, dapagliflozin increased the expression of HIF1, AMP-activated protein kinase (AMPK), and ERK and increased cell survival of hypoxic HK2 cells in a dose-dependent manner. In conclusion, dapagliflozin attenuates renal IR injury. HIF1 induction by dapagliflozin may play a role in renoprotection against renal IR injury.

Renal Integrin-Linked Kinase Depletion Induces Kidney cGMP-Axis Upregulation: Consequences on Basal and Acutely Damaged Renal Function

Soluble guanylyl cyclase (sGC) is activated by nitric oxide (NO) and produces cGMP, which activates cGMP-dependent protein kinases (PKG) and is hydrolyzed by specific phosphodiesterases (PDE). The vasodilatory and cytoprotective capacity of cGMP-axis activation results in a therapeutic strategy for several pathologies. Integrin-linked kinase (ILK), a major scaffold protein between the extracellular matrix and intracellular signaling pathways, may modulate the expression and functionality of the cGMP-axis-related proteins. We introduce ILK as a novel modulator in renal homeostasis as well as a potential target for cisplatin (CIS)-induced acute kidney injury (AKI) improvement. We used an adult mice model of depletion of ILK (cKD-ILK), which showed basal increase of sGC and PKG expressions and activities in renal cortex when compared with wildtype (WT) littermates. Twenty-four h activation of sGC activation with NO enhanced the filtration rate in cKD-ILK. During AKI, cKD-ILK maintained the cGMP-axis upregulation with consequent filtration rates enhancement and ameliorated CIS-dependent tubular epithelial-to-mesenchymal transition and inflammation and markers. To emphasize the role of cGMP-axis upregulation due to ILK depletion, we modulated the cGMP axis under AKI in vivo and in renal cultured cells. A suboptimal dose of the PDE inhibitor ZAP enhanced the beneficial effects of the ILK depletion in AKI mice. On the other hand, CIS increased contractility-related events in cultured glomerular mesangial cells and necrosis rates in cultured tubular cells; ILK depletion protected the cells while sGC blockade with ODQ fully recovered the damage.

Sildenafil improves renal function in patients with pulmonary arterial hypertension

AIM

Elevated serum creatinine (sCr) and low estimated glomerular filtration rate (eGFR) are associated with poor outcomes in patients with pulmonary arterial hypertension (PAH) whereas sildenafil treatment improves PAH outcomes. This post hoc analysis assessed the effect of sildenafil on kidney function and links with clinical outcomes including 6-min walk distance, functional class, time to clinical worsening and survival.

METHODS

Patients with PAH received placebo or sildenafil 20, 40 or 80 mg three times daily in the SUPER-1 study and open-label sildenafil titrated to 80 mg three times daily (as tolerated) in the extension study.

RESULTS

Baseline characteristics were similar among groups (n = 277). PAH was mostly idiopathic (63%) and functional class II (39%) or III (58%). From baseline to week 12, kidney function improved (increased eGFR, decreased sCr) with sildenafil and worsened with placebo. In univariate logistic regression, improved kidney function was associated with significantly improved exercise and functional class (odds ratios 1.17 [95% CI 1.01, 1.36] and 1.21 [95% CI 1.03, 1.41], respectively, for sCr and 0.97 [95% CI 0.94, 0.99] and 0.97 [95% CI 0.94, 0.99] for eGFR, all P < 0.05). In patients who maintained or improved kidney function, time to worsening was significantly delayed (P < 0.02 for both kidney parameters). Observed trends towards improved survival were not significant. Patients with eGFR <60 (vs. ≥60) ml min(-1) 1.73 m(-2) appeared to have worse survival.

CONCLUSIONS

Sildenafil treatment was associated with improved kidney function in patients with PAH, which was in turn associated with improved exercise capacity and functional class, a reduced risk of clinical worsening, and a trend towards reduced mortality.

Protective effects of sildenafil citrate administration on cisplatin-induced ovarian damage in rats

The aim of this study is to evaluate the effects of sildenafil citrate on cisplatin-induced ovarian toxicity. Thirty-two female rats were divided into four groups. Group 1: saline control; group 2: cisplatin; group 3: sildenafil citrate; and group 4: cisplatin plus sildenafil citrate group. In groups 2 and 4, the rats were injected with 5 mg/kg cisplatin intraperitoneally (i.p.). In groups 3 and 4, the rats were injected with 1.4 mg/kg sildenafil citrate i.p. The ovaries were removed two weeks later in all groups. Histopathologic examination, follicle counting and classification were performed. The expression of anti-Müllerian hormone (AMH) was detected immunohistochemically in the ovarian tissues. Sildenafil alleviated cisplatin-induced histopathological changes in the ovarian tissue. Primordial, secondary and tertiary follicles were diminished in group 2 compared with group 1 (p < 0.05). Pretreatment with sildenafil citrate preserved primordial follicle count in group 4 compared with group 2, and the difference was statistically significant (p < 0.05). According to our results, immunoreactivity intensity of AMH was lower in group 2 compared with group 1 (92.4 ± 3.97 versus 88.8 ± 1.77) but not significantly, whereas immunoreactivity intensity of AMH was higher in group 4 compared with group 2 (88.8 ± 1.77 versus 94.1 ± 2.36; p < 0.05). Our results demonstrated that pretreatment with sildenafil citrate is beneficial for protecting the ovaries from cisplatin-induced damage. Sildenafil citrate can be a choice for fertility preservation.

Protective effects of C-type natriuretic peptide on cisplatin-induced nephrotoxicity in mice

PURPOSE

Cisplatin is a highly effective chemotherapeutic agent used to treat various malignancies, but its utility is compromised by its nephrotoxicity. C-type natriuretic peptide (CNP), a member of the natriuretic peptide family, exhibits anti-inflammatory effects by activating its specific receptor, guanylyl cyclase (GC)-B. CNP and GC-B receptor are known to be expressed in both the vascular endothelium and the kidney. The objective of this study was to investigate the renoprotective effects of CNP in a mouse model of cisplatin-induced nephrotoxicity.

METHODS

C57BL/6 mice were divided into three groups: normal control mice; cisplatin (20 mg/kg, intraperitoneal) mice treated with vehicle; and cisplatin mice treated with CNP (2.5 µg/kg/min, subcutaneous). At 72 h after cisplatin injection, urine, blood and kidney samples were collected. Urine and blood samples were examined biochemically. Histological findings and gene expression in kidney tissue were evaluated.

RESULTS

CNP reduced histological renal tubular damage and apoptosis induced by cisplatin and suppressed plasma blood urea nitrogen and creatinine levels, which were elevated by cisplatin administration. CNP treatment decreased the expression of kidney injury molecule-1 and monocyte chemoattractant protein-1, which were elevated in the kidney by cisplatin administration. CNP treatment attenuated the decrease in GC-B expression in cisplatin-induced kidney injury.

CONCLUSIONS

The present study is the first to show that CNP inhibits nephrotoxicity and kidney cell damage induced by cisplatin. The mechanism of action may involve down-regulation of inflammatory cytokine expression in cisplatin-induced kidney injury and attenuation of apoptosis in renal tubular cells.

The pseudoginsenoside F11 ameliorates cisplatin-induced nephrotoxicity without compromising its anti-tumor activity in vivo

The clinical use of cisplatin was severely limited by its associated nephrotoxicity. In this study, we investigated whether the pseudoginsenoside F11 had protective effects against cisplatin-induced nephrotoxicity. To clarify it, one in vivo model of cisplatin-induced acute renal failure was performed. The results showed that pretreatment with F11 reduced cisplatin-elevated blood urea nitrogen and creatinine levels, as well as ameliorated the histophathological damage. Further studies showed that F11 could suppress P53 activation, inverse the ratio of Bax/Bcl2 and the anti-oxidative and free radical levels induced by cisplatin, which in turn inhibited tubular cell apoptosis. Importantly, F11 enhanced rather than inhibited the anti-tumor activity of cispaltin in murine melanoma and Lewis lung cancer xenograft tumor models. Our findings suggested that administering F11 with cisplatin might alleviate the associated nephrotoxicity without compromising its therapeutic efficiency. This finding provides a novel potential strategy in the clinical treatment of cancer.

Renal denervation restores the baroreflex control of renal sympathetic nerve activity and heart rate in Wistar-Kyoto rats with cisplatin-induced renal failure

AIM

There is evidence that in chronic renal failure, the sympathetic nervous system is activated. This study investigated the role of the renal innervation in suppressing high- and low-pressure baroreflex control of renal sympathetic nerve activity and heart rate in cisplatin-induced renal failure.

METHODS

Renal failure was induced using cisplatin (5 mg kg(-1) , i.p.) and the rats used 7 days later. Groups of rats were anaesthetized and prepared for measurement of renal sympathetic nerve activity and heart rate. Acute unilateral or bilateral renal denervation was performed, and renal sympathetic nerve activity and heart rate baroreflex gain curves were generated while the cardiopulmonary receptors were stimulated using an acute saline volume load.

RESULTS

Cisplatin administration reduced (P < 0.05) glomerular filtration rate by 27%, increased sodium fractional excretions fourfold, plasma creatinine and kidney index by 39 and 30% respectively, (all P < 0.05) compared with control rats. In the renal failure rats, baroreflex sensitivity for renal sympathetic nerve activity and heart rate was reduced (P < 0.05) by 29% and 27% (both P < 0.05) compared with control animals. Bilateral, but not unilateral, renal denervation restored baroreflex sensitivity to normal values. Volume expansion reduced (P < 0.05) renal sympathetic nerve activity by 34% in control rats, but remained unchanged in the renal failure rats. Unilateral and bilateral renal denervation progressively restored the volume expansion induced renal sympathoinhibition to control values.

CONCLUSION

These findings reveal a significant role of the renal sensory innervation in cisplatin-damaged kidneys which blunt the normal baroreflex control of renal sympathetic nerve activity.

cGMP-selective phosphodiesterase inhibitors stimulate mitochondrial biogenesis and promote recovery from acute kidney injury

Recent studies demonstrate that mitochondrial dysfunction is a mediator of acute kidney injury (AKI). Consequently, restoration of mitochondrial function after AKI may be key to the recovery of renal function. Mitochondrial function can be restored through the generation of new, functional mitochondria in a process called mitochondrial biogenesis (MB). Despite its potential therapeutic significance, very few pharmacological agents have been identified to induce MB. To examine the efficacy of phosphodiesterase (PDE) inhibitors (PDE3: cAMP and cGMP activity; and PDE4: cAMP activity) in stimulating MB, primary cultures of renal proximal tubular cells (RPTCs) were treated with a panel of inhibitors for 24 hours. PDE3, but not PDE4, inhibitors increased the FCCP-uncoupled oxygen consumption rate (OCR), a marker of MB. Exposure of RPTCs to the PDE3 inhibitors, cilostamide and trequinsin, for 24 hours increased peroxisome proliferator-activated receptor γ coactivator-1α, and multiple mitochondrial electron transport chain genes. Cilostamide and trequinsin also increased mRNA expression of mitochondrial genes and mitochondrial DNA copy number in mice renal cortex. Consistent with these experiments, 8-Br-cGMP increased FCCP-uncoupled OCR and mitochondrial gene expression, whereas 8-Br-cAMP had no effect. The cGMP-specific PDE5 inhibitor sildenafil also induced MB in RPTCs and in vivo in mouse renal cortex. Treatment of mice with sildenafil after folic acid-induced AKI promoted restoration of MB and renal recovery. These data provide strong evidence that specific PDE inhibitors that increase cGMP are inducers of MB in vitro and in vivo, and suggest their potential efficacy in AKI and other diseases characterized by mitochondrial dysfunction and suppressed MB.

Luteolin ameliorates cisplatin-induced nephrotoxicity in mice through inhibition of platinum accumulation, inflammation and apoptosis in the kidney

The aim of this study was to investigate the effects of flavone luteolin against cisplatin (CP)-induced kidney injury in mice. Luteolin at doses of 10mg/kg was administered intraperitoneally (ip) once daily for 3 days following single CP (10 or 20mg/kg) ip injection. Mice were sacrificed 24h after the last dose of luteolin. The CP treatment significantly increased serum creatinine and blood urea nitrogen and induced pathohistological changes in the kidneys. Renal oxidative/nitrosative stress was evidenced by decreased glutathione (GSH) levels and increased 3-nitrotyrosine (3-NT) and 4-hydroxynonenal (4-HNE) formation as well as cytochrome P450 2E1 (CYP2E1) expression. The CP administration triggered inflammatory response in mice kidneys through activation of nuclear factor-kappaB (NF-κB) and overexpression of tumor necrosis factor-alpha (TNF-α) and cyclooxygenase-2 (COX-2). Simultaneously, the increase in renal p53 and caspase-3 expression indicated apoptosis of tubular cells. The administration of luteolin significantly reduced histological and biochemical changes induced by CP, decreased platinum (Pt) levels and suppressed oxidative/nitrosative stress, inflammation and apoptosis in the kidneys. These results suggest that luteolin is an effective nephroprotective agent, with potential to reduce Pt accumulation in the kidneys and ameliorate CP-induced nephrotoxicity.

Protective role of phosphatidylcholine against cisplatin-induced renal toxicity and oxidative stress in rats

Although cisplatin is widely used in the treatment of cancers, clinical use of cisplatin is limited due to its nephrotoxicity. Pathophysiological mechanism of cisplatin-induced renal toxicity is a complex process and has not been fully understand. Reactive oxygen species (ROS) and oxidative stress have been presumed to be involved in this damage process. Phosphatidylcholine (PC) has antioxidant effect and prevents oxidative stress. Therefore, the present study aimed to investigate potential protective effects of PC on cisplatin-induced renal damage in rat. We examined the protective effects of PC on cisplatin-induced renal damage by assessment of serum creatinine, BUN, lipid peroxidation, total glutathione, glutathione peroxidase activity, catalase activity, superoxide dismutase activity and histophathological changes. PC ameliorated cisplatin-induced increases in serum creatinine, urea and oxidative stress. PC also decreased tubular degeneration and hypertrophy of glomeruli. PC may have a protective effect against cisplatin-induced nephrotoxicity in rats via enhancing antioxidant enzyme activity.

Sildenafil protects against nitric oxide deficiency-related nephrotoxicity in cyclosporine A treated rats

Cyclosporine A (CsA) is the most widely used immunosuppressant in organ transplant surgery and in treatment of autoimmune disease. Nevertheless, animal and clinical studies have demonstrated that nephrotoxicity is the major adverse effect limiting the prolonged CsA therapeutic use. The present study aimed to investigate possible protective effect of sildenafil, a phoshodiestrase-5 inhibitor, on CsA-induced nephrotoxicity and various mechanism(s) underlies this effect. Male Wistar rats were administered CsA (20 mg/kg/day, s.c.) for 21 days alone or in combination with sildenafil (5 mg/kg/day, p.o.). Sildenafil exhibited nephroprotective effects as evidenced by significant decrease in serum creatinine and urea levels, spot urine albumin-creatinine ratio, as well as renal level of malondialdehyde, with a concurrent increase in renal levels of reduced glutathione and nitric oxide along with catalase activity compared to CsA-treated rats. [corrected]. Additionally, immunohistochemical analysis demonstrated that sildenafil treatment markedly reduced inducible nitric oxide synthase, tumor necrosis factor-alpha, and caspase-3 expressions, while expression of endothelial nitric oxide synthase was prominently enhanced. The protective effects of sildenafil were confirmed by renal histopathological examination. Pretreatment with l-nitro-arginine methyl ester (10 mg/kg/day, i.p.), a non-selective nitric oxide synthase inhibitor, reversed the protection afforded by sildenafil. Taken together, the current study highlighted the renoprotective effects of sildenafil against CsA-induced nephrotoxicity in rats, which might be mediated, in part, through nitric oxide pathway as well as antioxidant, anti-inflammatory, and anti-apoptotic activities.

Phosphodiesterase-5 inhibition attenuates early renal ischemia-reperfusion-induced acute kidney injury: assessment by quantitative measurement of urinary NGAL and KIM-1

Acute kidney injury (AKI) is a common clinical problem that still lacks effective treatment. Phosphodiesterase-5 (PDE5) inhibitors possess anti-apoptotic and anti-oxidant properties, making it a promising therapy for ischemia-reperfusion (I/R) injury of various organs. The present study evaluated the early nephroprotective effects of Tadalafil, a PDE5 inhibitor, in an experimental model of renal I/R. Sprague-Dawley rats were divided into two groups: vehicle-treated I/R (n = 10), and Tadalafil (10 mg/kg po)-treated I/R group (n = 11). After removal of the right kidney and collection of two baseline urine samples, the left renal artery was clamped for 45 min followed by reperfusion for 60, 120, 180, and 240 min. Functional and histological parameters of the kidneys from the various groups were determined. In the vehicle-treated I/R group, glomerular filtration rate was significantly reduced compared with that in normal kidneys. In addition, the ischemic kidney showed remarkable cast formation, necrosis, and congestion, a consistent pattern of acute tubular necrosis. Furthermore, urinary excretion of NGAL and KIM-1, two novel biomarkers of kidney injury, substantially increased following I/R insult. In contrast, Tadalafil treatment resulted in a significant improvement in kidney function and amelioration of the adverse histological alterations of the ischemic kidney. Noteworthy, the urinary excretion of NGAL and KIM-1 markedly decreased in the Tadalafil-treated I/R group. These findings demonstrate that Tadalafil possesses early nephroprotective effects in rat kidneys subjected to I/R insult. This approach may suggest a prophylactic therapy for patients with ischemic AKI.

Mirtazapine protects against cisplatin-induced oxidative stress and DNA damage in the rat brain

AIM

Cisplatin chemotherapy is associated with neurotoxicity, and oxidative stress might play an important role in the pathogenesis. Mirtazapine may be a preventative agent via its less-known antioxidant properties. The aim of this study was to examine the potential chemoprotective effects of mirtazapine against cisplatin-induced oxidative stress and DNA damage.

METHODS

Twenty-four rats were divided equally into four groups: control; cisplatin (10 mg/kg i.p.); cisplatin plus mirtazapine (10-30 mg/kg, respectively i.p and p.o.); and mirtazapine (30 mg/kg p.o.). The rats were killed at the end of the 14th day of treatment. Brain tissue was examined with regard to antioxidant/oxidant biochemical parameters.

RESULTS

Although glutathione (tGSH) and nitric oxide (NO) end product mean scores were found to be statistically higher in the control group when compared with the cisplatin group (72.44% and 61.99% percentage change [PC], respectively), malondialdehyde (MDA), myeloperoxidase (MPO), and 8-hydroxyguanine (8-OH-GUA) mean scores were statistically lower in the control group in comparison with the cisplatin group (-55.48%, -67.99%, and -48.81% PC, respectively; P < 0.01). Finally, tGSH and NO end product levels were restored to normal (85.90% and 55.30% PC, respectively), and MDA, MPO, and 8-OH-GUA were significantly reduced by treatment with mirtazapine (-60.50%, -78.59%, and -38.10% PC, respectively; P < 0.01).

CONCLUSION

Mirtazapine has chemoprotective effects against cisplatin-induced oxidative stress and DNA damage in the rat brain, which may be attributed to its antioxidant capabilities. It would be useful to investigate whether cisplatin at the desired doses can be given concurrently with mirtazapine.

Vitamin E, Vitamin C, or Losartan Is Not Nephroprotectant against Cisplatin-Induced Nephrotoxicity in Presence of Estrogen in Ovariectomized Rat Model

Background. The nephroprotective effect of vitamins E and C or losartan against cisplatin (CP)- induced nephrotoxicity when they are accompanied by estrogen was investigated. Methods. The ovariectomized rats received estradiol valerate for two weeks. At the end of the first week, a single dose of CP (7 mg/kg, IP) was also administered, and they received placebo (group 1), vitamin E (group 2), vitamin C (group 3), or losartan (group 4) every day during the second week, and they were compared with another three control groups. Results. CP alone increased the serum levels of blood urea nitrogen (BUN), creatinine (Cr), and kidney tissue damage score (KTDS), significantly (P < 0.05), however at the presence of estradiol and CP, vitamin C, vitamin E, or losartan not only did not decrease these parameters, but also increased them significantly (P < 0.05). The serum level of superoxidase dismutase (SOD) was reduced by CP (P < 0.05), but it was increased when estradiol or estradiol plus vitamin C or losartan were added (P < 0.05). Conclusion. The particular pharmacological dose of estrogen used in this study abolish the nephroprotective effects vitamins C and E or losartan against CP-induced nephrotoxicity.

Evaluation of chinese-herbal-medicine-induced herb-drug interactions: focusing on organic anion transporter 1

The consumption of Chinese herbal medicines (CHMs) is increasing exponentially. Many patients utilize CHMs concomitantly with prescription drugs in great frequency. Herb-drug interaction has hence become an important focus of study. Transporter-mediated herb-drug interactions have the potential to seriously influence drug efficacy and toxicity. Since organic anion transporter 1 (OAT1) is crucial in renal active secretion and drug-drug interactions, the possibility of modulation of OAT1-mediated drug transport should be seriously concerned. Sixty-three clinically used CHMs were evaluated in the study. An hOAT1-overexpressing cell line was used for the in vitro CHMs screening, and the effective candidates were administered to Wistar rats to access renal hemodynamics. The regulation of OAT1 mRNA expression was also examined for further evidence of CHMs affecting OAT1-mediated transport. Among all the 63 CHMs, formulae Gui Zhi Fu Ling Wan (GZ) and Chia Wei Hsiao Yao San (CW) exhibited significant inhibitions on hOAT1-mediated [³H]-PAH uptake in vitro and PAH clearance and net secretion in vivo. Moreover, GZ showed concentration-dependent manners both in vitro and in vivo, and the decrease of rOAT1 mRNA expression indicated that GZ not only inhibited function of OAT1 but also suppressed expression of OAT1.

Cilastatin protects against cisplatin-induced nephrotoxicity without compromising its anticancer efficiency in rats

Cisplatin is an anticancer agent marred by nephrotoxicity; however, limiting this adverse effect may allow the use of higher doses to improve its efficacy. Cilastatin, a small molecule inhibitor of renal dehydropeptidase I, prevents proximal tubular cells from undergoing cisplatin-induced apoptosis in vitro. Here, we explored the in vivo relevance of these findings and the specificity of protection for kidney cells in cisplatin-treated rats. Cisplatin increased serum blood urea nitrogen and creatinine levels, and the fractional excretion of sodium. Cisplatin decreased the glomerular filtration rate, promoted histological renal injury and the expression of many pro-apoptotic proteins in the renal cortex, increased the Bax/Bcl2 ratio, and oxidative stress in kidney tissue and urine. All these features were decreased by cilastatin, which preserved renal function but did not modify the pharmacokinetics of cisplatin area under the curve. The cisplatin-induced death of cervical, colon, breast, and bladder-derived cancer cell lines was not prevented by cilastatin. Thus, cilastatin has the potential to prevent cisplatin nephrotoxicity without compromising its anticancer efficacy.

C-phycocyanin attenuates cisplatin-induced nephrotoxicity in mice

Although cisplatin is a highly effective antineoplastic agent, nephrotoxicity is its major clinical problem. Recently, it was reported that Spirulina, a blue-green algae, has potent antioxidant properties. The aim of this study was to establish the possible protective role of C-phycocyanin (PC), one of the active ingredients of Spirulina, against cisplatin-induced nephrotoxicity. This study was carried out using human kidney-2 (HK-2) cells and male C57BL6 mice. Cells and mice were divided into four groups; untreated control group, PC-treated control group, cisplatin-treated group, and PC plus cisplatin-treated group. The molecular, functional, and structural parameters were measured. PC significantly attenuated blood urea nitrogen, serum creatinine, renal histological damages, and apoptotic cell death in cisplatin-treated mice. The cisplatin-induced cell death was significantly attenuated in cells pretreated with PC. PC also significantly attenuated the elevation of p-ERK, p-JNK, and p-p38 induced by cisplatin treatment. The expression of Bax, caspase-9, and caspase-3 in cisplatin-treated cells were also decreased by PC treatment. In conclusion, PC ameliorates cisplatin-induced nephrotoxicity and, at least in part, suppression of p-ERK, p-JNK, p-p38, Bax, caspase-9, and caspase-3 may be involved in this mechanism.