Lipid peroxidation accompanies cyclosporine nephrotoxicity: effects of vitamin E

Role of cyclosporin A in the treatment of kidney disease and nephrotoxicity

The clinical use of cyclosporin A (CsA) has led to significant advances and achievements in the field of transplantation and immune diseases. However, the nephrotoxicity of CsA is a major concern in current immunosuppression regimens. CsA causes abnormal kidney function while treating kidney disease, causing problems for clinicians and patients. Evidence of CsA nephrotoxicity is almost always present in transplant recipients after long-term CsA administration (up to 10 years), and similar phenomena occur with other calcineurin inhibitors. In this review, we summarize the mechanisms and influencing factors of CsA for the treatment of primary nephrotic syndrome. The mechanisms of CsA nephrotoxicity, clinical-pathological features, diagnosis, prevention strategies, and risk factors are summarized. We discuss the correlates and mechanisms of the switch between kidney disease prevention and nephrotoxicity of CsA to better understand the function of CsA in the kidney and to provide a basis for the prevention and treatment of CsA nephrotoxicity.

Chronic interstitial nephritis in agricultural communities (CINAC) and lysosomal tubulopathy: Is there a place for anti-oxidants?

Chronic Interstitial Nephritis in Agricultural Communities (CINAC) continues to attract controversy in the scientific community. It was previously known as Chronic Kidney Disease of Unknown Etiology (CKDu) and is not associated with the common aetiological factors such as diabetes. There is general acceptance that it is an environmentally induced disorder due to a combination of toxicities: heavy metals from food, fluoride in drinking water, hard water, heat stress and pesticides. The recent findings of a lysosomal inclusion body tubulopathy is of great interest to those attempting to find therapeutic agents to slow or eliminate its renal damage. The paper argues that despite these new findings, oxidative stress could play a key role and proposes that anti-oxidants such as Vitamin C and E be repurposed for treatment.

Cyclosporin A aggravates hydrogen peroxide-induced cell death in kidney proximal tubule epithelial cells

Cyclosporin A (CsA) does not only exert a toxic effect on kidney parenchymal cells, but also protects them against necrotic cell death by inhibiting opening of mitochondrial permeability transition pore. However, whether CsA plays a role in hydrogen peroxide-induced kidney proximal tubular cell death is currently unclear. In the present study, treatment with CsA further increased apoptosis and necrosis in HK-2 human kidney proximal tubule epithelial cells during exposure to hydrogen peroxide. In addition, hydrogen peroxide-induced p53 activation and BH3 interacting-domain death agonist (BID) expression were higher in CsA-treated cells than those in non-treated cells, whereas hydrogen peroxide-induced activation of mitogen-activated protein kinases including p38, c-Jun N-terminal kinase, and extracellular signal-regulated kinase and activation of protein kinase B were not significantly altered by treatment with CsA. In oxidant-antioxidant system, reactive oxygen species (ROS) production induced by hydrogen peroxide was further enhanced by treatment with CsA. However, expression levels of antioxidant enzymes including manganese superoxide dismutase, copper/zinc superoxide dismutase, and catalase were not altered by treatment with hydrogen peroxide or CsA. Treatment with CsA further enhanced mitochondrial membrane potential induced by exposure to hydrogen peroxide, although it did not alter endoplasmic reticulum stress based on expression of glucose-regulated protein 78 and 94. Taken together, these data suggest that CsA can aggravate hydrogen peroxide-induced cell death through p53 activation, BID expression, and ROS production.

The epoxyeicosatrienoic acid analog PVPA ameliorates cyclosporine-induced hypertension and renal injury in rats

The introduction of calcineurin inhibitors (CNI) into clinical practice in the late 1970s transformed organ transplantation and led to significant improvement in acute rejection episodes. However, despite their significant clinical utility, the use of these agents is hampered by the development of hypertension and nephrotoxicity, which ultimately lead to end-stage kidney disease and overt cardiovascular outcomes. There are currently no effective agents to treat or prevent these complications. Importantly, CNI-free immunosuppressive regimens lack the overall efficacy of CNI-based treatments and put patients at risk of allograft rejection. Cytochrome P-450 epoxygenase metabolites of arachidonic acid, epoxyeicosatrienoic acids (EETs), have potent vasodilator and antihypertensive properties in addition to many cytoprotective effects, but their effects on CNI-induced nephrotoxicity have not been explored. Here, we show that PVPA, a novel, orally active analog of 14,15-EET, effectively prevents the development of hypertension and ameliorates kidney injury in cyclosporine-treated rats. PVPA treatment reduced proteinuria and renal dysfunction induced by cyclosporine. PVPA inhibited inflammatory cell infiltration into the kidney and decreased renal fibrosis. PVPA also reduced tubular epithelial cell apoptosis, attenuated the generation of reactive oxygen species, and modulated the unfolded protein response that is associated with endoplasmic reticulum stress. Consistent with the in vivo data, PVPA attenuated cyclosporine-induced apoptosis of NRK-52E cells in vitro. These data indicate that the cytochrome P-450/EET system offers a novel therapeutic strategy to treat or prevent CNI-induced nephrotoxicity.

Protection against Cyclosporine-Induced Reprotoxicity by Satureja khuzestanica Essential Oil in Male Rats

Background

The effects of cyclosporine (Cs), a fungal cyclic polypeptide with potent immunosuppressive activity, on fertility have assumed greater significance with the increasing numbers of transplantations being performed all over the world. Current study was undertaken to investigate the potential of Satureja khuzestanica Essential Oil (SEO) as an antioxidant to mitigate Cs-induced reprotoxicity.

Materials and Methods

In this experimental study (April-July 2012), thirty-two adult male Wistar rats were randomly divided into 4 groups of 8 animals each. Two groups of rats were administered Cs [40 mg/kg/day, per oral (p.o.)] for 45 days. One of these groups received SEO (225 mg/kg/day, p.o.) four hours after Cs administration. A vehicle-treated control group and a SEO control group were also included. Epididymal sperm characteristics, in vitro fertilizing capacity as well as embryo development were evaluated. For statistical analysis, one-way ANOVA and Tukey’s post-hoc test were used, and the value of P<0.05 was considered as the criterion for statistical significance.

Results

Sperm count and viability along with fertilization and blastocyst development rates were significantly decreased by Cs treatment. Moreover, Cs-treated group showed significant increases in DNA damage, protamine deficiency of the sperm cells and proportion of spermatozoa with cytoplasmic droplet. Notably, aforementioned parameters were improved to near normal level by SEO co-administration.

Conclusion

These results suggest that SEO has a protective action against Cs-induced reprotoxicity in a rat model.

Vasopressin attenuates ischemia-reperfusion injury via reduction of oxidative stress and inhibition of mitochondrial permeability transition pore opening in rat hearts

Aim of this study was to investigate the involvement of the mitochondrial permeability transition pore (MPTP) and oxidative stress in the cardioprotective effect of vasopressin (AVP) on ischemia/reperfusion (I/R) injury. Anesthetized male wistar rats were subjected to regional 30 min ischemia and 120 min reperfusion and randomly divided into nine groups: (1) Control; saline was administered intravenously before ischemia, (2) vasopressin was administrated 10 min prior to ischemia, (3, 4) Atractyloside as MPTP opener, was injected 5 min prior to reperfusion without and with vasopressin, (5, 6) Cyclosporine A as a MPTP closer, was injected 5 min prior to reperfusion without and with vasopressin, (7) mitochondria were isolated from control group and CaCl2 was added as MPTP opener and swelling inducer, (8) isolated mitochondria from Control hearts was incubated with Cyclosporine A before adding the CaCl2 (9) CaCl2 was added to isolated mitochondria from vasopressin group. Infusion of vasopressin decreased infarct size (18.6±1.7% vs. control group 37.6±2.4%), biochemical parameters [LDH (Lactate Dehydrogenase), CK-MB (Creatine Kinase-MB) and MDA (Malondialdehyde) plasma levels, PAB (Prooxidant-antioxidant balance)] compared to control group. Atactyloside suppressed the cardioprotective effect of vasopressin (32.5±1.9% vs. 18.6±1.7%) but administration of the Cyclosporine A without and with vasopressin significantly reduced infarct size to 17.7±4% (P<0.001) and 22.7±3% (P<0.01) respectively, vs. 37.6±2.4% in control group. Also, vasopressin, similar to Cyclosporine A, led to decrease in CaCl2-induced swelling. It seems that vasopressin through antioxidant effect and MPTP inhibition has created a cardioprotection against ischemia/reperfusion injuries.

Biomarkers of calcineurin inhibitor nephrotoxicity in transplantation

Over 35 years of use has demonstrated the revolutionary therapeutic benefits of calcineurin inhibitors (CNI) in not only preventing transplant rejection, but also the renal and nonrenal toxicity of CNI. Acute reversible and insidious irreversible forms of CNI nephrotoxicity have been identified, with ischemia from an imbalance between vasoconstrictors and vasodilators playing an important role. The ongoing search to define toxicity pathways has been enriched by ‘Omics’ studies. Changes in proteins including those involved in activation of pro-inflammatory responses, oxidative stress, ER stress and the unfolded protein response have been identified, and these may serve as biomarkers of toxicity. However, the current standard of CNI toxicity, histology, lacks specificity, which creates challenges for biomarker validation. This review focuses on progress in nephrotoxic pathway identification of CNI and biomarker validation.

A comparative study on renal biopsy before and after long-term calcineurin inhibitors therapy: an insight for pathogenesis of its toxicity

Calcineurin inhibitors (CNIs) are effective immunosuppressive agents for the successful treatment of childhood steroid-resistant nephrotic syndrome (SRNS). Because these patients require long-term treatment, the identification of early markers of CNI-induced nephrotoxicity (CNIN) is imperative. The monitoring of CNI trough levels, serum creatinine, and glomerular filtration rate is not an accurate marker of CNIN. The present study has been undertaken to identify early markers of CNIN in SRNS patients. Twenty-four pediatric SRNS patients were included with paired renal biopsies, before initiation (time zero biopsy) and at least 1 year after CNI therapy (protocol renal biopsy) with standard dosage. Semiquantitative morphologic grading of the histologic features was done for assessing CNIN. Immunohistochemical markers for oxidative stress (nitrotyrosine [NT]), fibrogenic cytokine (transforming growth factor β1 [TGF-β1]), and endothelial injury (endothelial nitric oxide synthase [eNOS]) were evaluated. In addition, ultrastructural study was done to assess mitochondrial injury in endothelial and tubular epithelial cells. The protocol renal biopsies in comparison with time zero biopsies showed significant increase in glomerulosclerosis, juxtaglomerular apparatus hyperplasia, tubular atrophy, interstitial fibrosis, arteriolar hyalinosis, and smooth muscle vacuolization (P < .05 - P < .001). Significantly higher immunoexpression of eNOS (91.6%), NT (71%), and TGF-β1 (87.5%) was noted in posttreatment biopsies. Mean mitochondrial injury grade among post-CNI cases in endothelial cells and proximal tubular cells was 2.28 and 1.4, whereas in pre-CNI, it was 0.28 and 0.27, respectively. We propose that immunohistochemical overexpression of NT, eNOS, and TGF-β1 is an early marker of CNIN. Endothelial and proximal tubular mitochondrial injury may play an important role in the pathogenesis of CNIN.

Recognition of malondialdehyde-modified proteins by the C terminus of complement factor H is mediated via the polyanion binding site and impaired by mutations found in atypical hemolytic uremic syndrome

Atypical hemolytic uremic syndrome (aHUS) is a severe thrombotic microangiopathy characterized by uncontrolled complement activation against endothelial and blood cells. Mutations in the C-terminal target recognition domains 19-20 of complement regulator factor H (FH) are strongly associated with aHUS, but the mechanisms triggering disease onset have remained unresolved. Here we report that several aHUS-related mutations alter the binding of FH19-20 to proteins where lysines have reacted with malondialdehyde (MDA). Although FH19-20 did not interact with MDA-modified hexylamine, lysine-containing peptides, or a proteolytically degraded protein, it bound to MDA-modified polylysine. This suggests that FH19-20 recognizes only clustered MDA adducts. Binding of MDA-modified BSA to FH19-20 was ionic by nature, depended on positive residues of FH19-20, and competed with the polyanions heparin and DNA. This could not be explained with the mainly neutral adducts known to form in MDA modification. When positive charges of lysines were eliminated by acetic anhydride instead of MDA, the acetylated BSA started to bind FH19-20. Together, these results indicate that negative charges on the modified proteins dominate the interaction with FH19-20. This is beneficial for the physiological function of FH because by binding to the negative charges of the modified target, FH could prevent excess complement activation initiated by naturally occurring antibodies recognizing MDA epitopes with multiple different structures. We propose that oxidative stress leading to formation of MDA adducts is a common feature for triggers of aHUS and that failure of FH in protecting MDA-modified surfaces from complement activation is involved in the pathogenesis of the disease.

Human adipose tissue derived mesenchymal stem cells aggravate chronic cyclosporin nephrotoxicity by the induction of oxidative stress

The aim of this study was to investigate whether hATMSCs protect against cyclosporine (CsA)-induced renal injury. CsA (7.5 mg/kg) and hATMSCs (3×10⁶/5 mL) were administered alone and together to rats for 4 weeks. The effect of hATMSCs on CsA-induced renal injury was evaluated by assessing renal function, interstitial fibrosis, infiltration of inflammatory cells, and apoptotic cell death. Four weeks of CsA-treatment produced typical chronic CsA-nephropathy. Combined treatment with CsA and hATMSCs did not prevent these effects and showed a trend toward further renal deterioration. To evaluate why hATMSCs aggravated CsA-induced renal injury, we measured oxidative stress, a major mechanism of CsA-induced renal injury. Both urine and serum 8-hydroxydeoxyguanosine(8-OHdG) levels were higher in the CsA+hATMSCs group than in the CsA group (P<0.05). An in vitro study showed similar results. Although the rate of apoptosis did not differ significantly between HK-2 cells cultured in hATMSCs-conditioned medium and those cultured in DMEM, addition of CsA resulted in greater apoptosis in HK-2 cells cultured in hATMSCs-conditioned medium. Addition of CsA increased oxidative stress in the hATMSCs-conditioned medium. The results of our study suggest that treatment with hATMSCs may aggravate CsA-induced renal injury because hATMSCs cause oxidative stress in the presence of CsA.

Nox2 is a mediator of chronic CsA nephrotoxicity

We hypothesized that Nox2, the classical phagocytic NADPH oxidase, plays an important role in calcineurin inhibitor (CNI)-induced renal fibrosis. We tested this hypothesis in vitro, in animal and in human studies. Cyclosporine A (CsA) and tacrolimus (TAC) were associated with greater levels of Nox2 mRNA and epithelial to mesenchymal transition (EMT) in NRK52E cells. CsA increased Nox2, α-SMA and phosphorylated-p38MAPK, Smad3 and NFκB proteins. Nox2 upregulation and EMT were inhibited in TGF-β1 knockout cells suggesting that TGF-β1 is required for Nox2 activation. Fisher344 rats treated with high dose CsA showed increased Nox2 in the tubulointerstitium and greater Nox2, α-SMA, phosphorylated Smad3 and nitrotyrosine by immunoblot analyses. Inhibition of Nox2 by coadministration of apocynin or diphenyleneiodonium was associated with reduced fibrogenesis. We validated these findings by treating wild type and Nox2 null (B6.129S-Cybb(Tm1Din)/J) mice with high dose CsA. Western blot analyses confirmed the absence of Nox2 and significantly lower levels of α-SMA and 4-hydroxynonenal (HNE) in CsA-treated knockout mice. These findings were clinically relevant since Nox2 and α-SMA were increased in the tubulointerstitium of kidneys from 15 liver transplant recipients with biopsy-confirmed chronic CsA or TAC nephrotoxicity. In conclusion, specific Nox2 inhibition strategies may improve chronic CNI nephrotoxicity in solid organ transplantation.

Crosstalk between central pathways of nitric oxide and carbon monoxide in the hypertensive action of cyclosporine

Although the intermediary role of central neurons in the hypertensive and sympathoexcitatory actions of cyclosporine (CSA) has been recognized in previous studies including our own, the underlying mechanism remains obscure. In this study, we tested the hypothesis that central pathways of nitric oxide (NO) and carbon monoxide (CO) modulate the blood pressure (BP) response elicited by CSA in conscious rats. Hemodynamic effects of CSA were evaluated in absence and presence of maneuvers that inhibit or facilitate biosynthesizing enzymes of NO (NOS) or CO (heme oxygenase, HO). CSA (20mg/kg i.v.) produced abrupt increases in BP that peaked in 5min and maintained for at least 45min. The hypertensive effect of CSA disappeared in rats pretreated intracisternally (i.c.) with N(ω)-nitro-l-arginine methyl ester (L-NAME, nonselective NOS inhibitor), N(5)-(1-iminoethyl)-l-ornithine (L-NIO, selective eNOS inhibitor), N(ω)-propyl-l-arginine (NPLA, selective nNOS inhibitor), or 1H-[1,2,4] oxadiazolo[4,3-a] quinoxalin-1-one (ODQ, guanylate cyclase inhibitor), suggesting the importance of central eNOS/nNOS/GC cascade in CSA-induced hypertension. L-NAME also abolished the hypotension caused by the sympatholytic drug moxonidine, indicating a tonic sympathoinhibitory action for NO. The inhibition of HO activity by zinc protoporphyrin IX (ZnPP) abrogated the hypertensive action of CSA. The abolition by L-NAME or ZnPP of CSA hypertension was compromised upon simultaneous i.c. exposure to hemin (HO substrate) and l-arginine (NOS substrate), respectively. Together, the interruption of the mutually facilitated NOS/NO and HO/CO pathways and coupled GC/cGMP in central neuronal pools accounts, at least partly, for the hypertensive and perhaps sympathoexcitatory actions of CSA.

Cyclosporin A and tacrolimus induce renal Erk1/2 pathway via ROS-induced and metalloproteinase-dependent EGF-receptor signaling

We previously demonstrated that the widely used immunosuppressive drugs cyclosporin A (CsA) and tacrolimus (FK506), independent of immunophilin binding, can activate profibrogenic transforming growth factor β (TGFβ)/Smad signaling cascades in rat renal mesangial cells (MC). Here we report that both peptidyl-prolyl cis/trans isomerase (PPIase) inhibitors activate the extracellular-signaling regulated kinase (ERK) a member of the mitogen activated protein kinase (MAPK) and induce a rapid and transient increase in ERK phosphorylation. The MEK inhibitor U0126, the reactive oxygen species (ROS) scavenger N-acetyl-cysteine (NAC), a cell-permeant superoxide dismutase (SOD) and stigmatellin, an inhibitor of mitochondrial cytochrome bc1 complex strongly attenuated the increase in ERK1/2 phosphorylation triggered by PPIase inhibitors. Moreover, neutralizing antibodies against heparin binding-epidermal growth factor (HB-EGF), and inhibition of the EGF receptor by either small interfering (si)RNA or AG1478, demonstrate that ERK activation by both PPIase inhibitors is mediated via HB-EGF-induced EGF receptor (EGFR) tyrosine kinase activation. The strong inhibitory effects achieved by GM6001 and TAPI-2 furthermore implicate the involvement of a desintegrin and metalloproteinase 17 (ADAM17). Concomitantly, the PPIase inhibitor-induced ADAM17 secretase activity was significantly reduced by SOD and stigmatellin thus suggesting that mitochondrial ROS play a primary role in PPIase inhibitor-induced and ADAM17-mediated HB-EGF shedding. Functionally, both immunosuppressants caused a strong increase in MC proliferation which was similarly impeded when cells were treated in the presence of NAC, TAPI-2 or AG1478, respectively. Our data suggest that CsA and FK506, via ROS-dependent and ADAM17-catalyzed HB-EGF shedding induce the mitogenic ERK1/2 signaling cascade in renal MC.

Biomarkers of immunosuppressant organ toxicity after transplantation: status, concepts and misconceptions

INTRODUCTION

A major challenge in transplantation is improving long-term organ transplant and patient survival. Immunosuppressants protect the transplant organ from alloimmune reactions, but sometimes also exhibit limiting side effects. The key to improving long-term outcome following transplantation is the selection of the correct immunosuppressive regimen for an individual patient for minimizing toxicity while maintaining immunosuppressive efficacy.

AREAS COVERED

Proteomics and metabolomics have the potential to develop sensitive and specific diagnostic tools for monitoring early changes in cell signal transduction, regulation and biochemical pathways. Here, we review the steps required for the development of molecular markers from discovery, mechanistic and clinical qualification to regulatory approval, and present a critical discussion of the current status of molecular marker development as relevant for the management and individualization of immunosuppressive drug regimens.

EXPERT OPINION

Although metabolomics and proteomics-based studies have yielded several candidate molecular markers, most published studies are poorly designed, statistically underpowered and/or often have not gone beyond the discovery stage. Most molecular marker candidates are still at an early stage. Due to the high complexity of and the resources required for diagnostic marker development, initiatives and consortia organized and supported by funding agencies and regulatory agencies will be critical.

Evaluation of efficacy of vitamin E and N-acetyl cysteine in gentamicin-induced nephrotoxicity in rats

Gentamicin (GM), an aminoglycoside, is widely employed in clinical practice for the treatment of serious gram-negative infections. The clinical utility of GM is limited by the frequent incidence of acute renal failure. This study was designed to investigate treatment and posttreatment renoprotective potential of vitamin E and N-acetyl cysteine (NAC) against GM-induced oxidative stress and renal dysfunction. Male Sprague-Dawley rats were divided into six groups: first group is the control group that received olive oil (0.1 mL/100 g B.W.), second is the one that was treated with GM (80 mg/kg/i.p./8 days), third is the one that was treated with GM (80 mg/kg/i.p./8 days) and vitamin E (50 mg/kg/i.p./8 days), fourth is the one that was treated with GM (80 mg/kg/i.p./8 days) and NAC (50 mg/kg/i.p./8 days), fifth is the one that was treated with GM (80 mg/kg/i.p./8 days), vitamin E (50 mg/kg/i.p./8 days), and NAC (50 mg/kg/i.p./8 days), and sixth is the one that was treated with GM initially for 8 days (at 80 mg/kg/i.p.) after which vitamin E (at 50 mg/kg/i.p.) and NAC (at 50 mg/kg/i.p.) were administered for 8 days. Serum creatinine, blood urea nitrogen, serum glucose, renal malondialdehyde, renal reduced glutathione, urine sodium, fractional excretion of sodium, and histopathological examination of kidney were performed after treatment. Gentamicin treatment caused nephrotoxicity as evidenced by marked elevation in serum creatinine, blood urea nitrogen, renal malondialdehyde, urine sodium, and fractional excretion of sodium. Study of renal morphology showed marked loss of epithelium in proximal convoluted tubule, inflammatory infiltrate in the form of lymphocytes, mainly in interstitium. Treatment and posttreatment with vitamin E and NAC significantly restored renal functions, reduced lipid peroxidation, enhanced reduced glutathione level, and restored the biochemical parameters. The results of this study demonstrate the therapeutic potential of vitamin E and NAC in gentamicin-induced nephrotoxicity.

Study on toxicological aspects of crystal-mediated nephrotoxicity induced by FYX-051, a xanthine oxidoreductase inhibitor, in rats

To clarify the toxicological aspects of crystal-mediated nephrotoxicity, we performed analysis concerning the correlation between representative kidney-related parameters and renal histopathology, using the individual data obtained from the 4-week toxicity studies of FYX-051, a xanthine oxidoreductase inhibitor, by oral administration at 1 and 3 mg/kg to Sprague-Dawley (SD) rats and at 3 and 10 mg/kg to F344 rats. In SD rats, the correlation coefficient on histopathology between the right and left kidneys was 0.7826 and remained within a lower range of strong correlation (range: ±0.7 ∼ ±0.9). The correlation coefficient between body-weight gains, urinary volume, osmolarity, serum blood urea nitrogen (BUN), creatinine, and relative kidney weights and renal histopathology was -0.6648, 0.7896, -0.7751, 0.8195, 0.8479, and 0.8969, respectively, showing a strong correlation, except a moderate correlation in body-weight gains (range: ±0.4 ∼ ±0.7). In F344 rats, the correlation coefficient on histopathology between the right and left kidneys was 0.8637, remaining within an upper range of strong correlation. The correlation coefficient between the above parameters and renal histopathology was -0.8175, 0.8616, -0.9045, 0.9010, 0.8991, and 0.9524, respectively, showing an extremely strong correlation in urinary osmolarity, serum BUN, and relative kidney weights (range: ±0.9 ∼ ±1.0). Therefore, the present study suggests that FYX-051-induced nephrotoxicity may occur with more inconsistency in the degree of nephropathy between the right and left kidneys in SD rats than in F344 rats, which would explain the above outcomes.

Fenoldopam preconditioning: role of heme oxygenase-1 in protecting human tubular cells and rodent kidneys against cold-hypoxic injury

BACKGROUND

Kidneys from brain-dead donors are cold preserved until transplanted. However, prolonged cold storage can contribute to allograft failure. Studies suggest that donor preconditioning with dopaminergics may reduce cold-ischemic transplant injury, but whether heme oxygenase (HO)-1 induction is an underlying mechanism is not known.

OBJECTIVE

To test whether preconditioning with fenoldopam (FD) induce HO-1 and protect kidneys against cold storage injury and whether HO-1 plays a role in protection.

METHOD

We used human renal proximal tubular epithelial cells, rat kidney transplants, and HO-1 null mice kidneys.

RESULTS

FD preconditioning of cells for 4 hr significantly protected against cell death from 24-hr cold hypoxia and was associated with a dose-dependent increase in HO-1 expression. In a syngeneic rat kidney transplant model, FD preconditioning for 18 hr markedly increased kidney HO-1 expression and protected kidneys against 24-hr cold-ischemic transplant injury. To test the role of HO-1, renal proximal tubular epithelial cells were treated with HO-1 small interfering RNA, followed by FD-preconditioning. Small interfering RNA inhibited the HO-1 messenger RNA expression and reversed the FD protection. Suspension of kidneys of HO-1 null and wild-type mice preconditioned with FD or saline were subjected to 24- and 48-hr cold storage. N-acetyl glucosaminidase, a specific tubular injury marker, was significantly lower in FD-preconditioned wild-type kidneys, but not in HO-1 null kidneys, suggesting a role for HO-1 in FD's preconditioning.

CONCLUSION

Our data suggest HO-1 induction as an underlying mechanism for FD preconditioning and support the idea of testing FD preconditioning in the clinical setting. Studies are required to determine the optimum FD-preconditioning protocol.

Toxicodynamic effects of ciclosporin are reflected by metabolite profiles in the urine of healthy individuals after a single dose

WHAT IS ALREADY KNOWN ABOUT THE SUBJECT * Ciclosporin's nephrotoxicity initially targets the proximal tubule and is, at least in part, driven by increased formation of oxygen radicals. * (1)H-nuclear magnetic resonance spectroscopy (NMR)- and mass spectrometry (MS)-based biochemical profiling (metabolomics) allows for the sensitive detection of metabolite pattern changes in urine. * In systematic studies in rats we showed that ciclosporin caused urine metabolite pattern changes typical for proximal tubule damage and that these pattern changes seemed to be more sensitive than established clinical kidney function markers such as serum creatinine concentrations. WHAT THIS PAPER ADDS * This study showed that urine metabolite pattern changes as assessed by (1)H-NMR and HPLC-MS are sensitive enough to detect the effect of ciclosporin as early as 4 h after a single oral dose. * In our previous rat studies, changes in urine metabolite pattern in response to ciclosporin translated into healthy humans, indicating the involvement of the same toxicodynamic mechanisms. * The results provide proof of concept for further development of this combination molecular marker strategy into diagnostic tools for the detection and monitoring of drug nephrotoxicity. AIMS The immunosuppressant ciclosporin is an efficient prophylaxis against transplant organ rejection but its clinical use is limited by its nephrotoxicity. Our previous systematic studies in the rat indicated urine metabolite pattern changes to be sensitive indicators of the negative effects of ciclosporin on the kidney. To translate these results, we conducted an open label, placebo-controlled, crossover study assessing the time-dependent toxicodynamic effects of a single oral ciclosporin dose (5 mg kg(-1)) on the kidney in 13 healthy individuals. METHODS In plasma and urine samples, ciclosporin and 15-F(2t)-isoprostane concentrations were assessed using HPLC-MS and metabolite profiles using (1)H-NMR spectroscopy. RESULTS The maximum ciclosporin concentrations were 1489 +/- 425 ng ml(-1) (blood) and 2629 +/- 1308 ng ml(-1) (urine). The increase in urinary 15-F(2t)-isoprostane observed 4 h after administration of ciclosporin indicated an increase in oxidative stress. 15-F(2t)-isoprostane concentrations were on average 2.9-fold higher after ciclosporin than after placebo (59.8 +/- 31.2 vs. 20.9 +/- 19.9 pg mg(-1) creatinine, P < 0.02). While there were no conclusive changes in plasma 15-F(2t)-isoprostane concentrations or metabolite patterns, non-targeted metabolome analysis using principal components analysis and partial least square fit analysis revealed significant changes in urine metabolites typically associated with negative effects on proximal tubule cells. The major metabolites that differed between the 4 h urine samples after ciclosporin and placebo were citrate, hippurate, lactate, TMAO, creatinine and phenylalanine. CONCLUSION Changes in urine metabolite patterns as a molecular marker are sufficiently sensitive for the detection of the negative effects of ciclosporin on the kidney after a single oral dose.

Effects of erdosteine on cyclosporine-A-induced hepatotoxicity in rats

Cyclosporine A (CsA) is a potent immunosuppressive agent used for organ transplantations and various autoimmune disorders. However, hepatotoxicity due to CsA remains one of the major side effects. The use of antioxidants reduces the adverse effects of CsA. The aim of this study was to determine the protective effects of erdosteine on CsA-induced liver injury through tissue oxidant/antioxidant parameters and to evaluate light microscopic alterations in rat-liver tissues. Rats were randomly divided into four experimental groups: The control group received sunflower oil (2 mL/kg/day, per orally; p.o.), while the other groups were treated with CsA (25 mg/kg/day, p.o.) or erdosteine (10 mg/kg/day, p.o.) or CsA+erdosteine, respectively. Serum aspartate aminotransferase and alanine aminotransferase levels, tissue malondialdehyde and nitric oxide levels, and superoxide dismutase, glutathione peroxidase and catalase enzyme activities were measured. Histological examination was performed. CsA caused a significant deterioration in the hepatic function tests, morphology, and gave rise to severe oxidative stress in the liver. Erdostein significantly improved the functional and histological parameters and attenuated the oxidative stresss induced by CsA. Erdostein protects liver tissue against oxygen free radicals and prevents hepatic dysfunction and morphological abnormalities associated with chronic CsA administration.

Macrophage depletion attenuates chronic cyclosporine A nephrotoxicity

BACKGROUND

Cyclosporine A (CsA)-induced chronic nephrotoxicity is characterized by renal dysfunction and interstitial fibrosis. Early and progressive renal macrophage influx, correlating with latter interstitial fibrotic areas, has been associated with CsA treatment. This study investigated the role of macrophages, the nitric oxide (NO) pathway, and the oxidative stress on chronic CsA nephrotoxicity.

METHODS

The macrophages were depleted by clodronate liposomes. Animals were distributed into four groups: vehicle (olive oil for 21 days), CsA 7.5 mg/kg per day (21 days), CsA plus clodronate (5 mg/mL intraperitoneally on days -4, 1, 4, 11, and 18 of CsA treatment), or vehicle plus clodronate. On day 22, glomerular filtration rate, renal blood flow, renal tubulointerstitial fibrosis, CsA blood levels, serum malondialdehyde and renal tissue immunohistochemistry for macrophages, inducible NO synthase, transforming growth factor-beta, nuclear factor-kbeta, alpha-smooth muscle actin, vimentin, and nitrotyrosine were assessed.

RESULTS

CsA-induced increase in the macrophage was prevented by clodronate. Macrophage depletion attenuated the reductions in the glomerular filtration rate and renal blood flow, the development of tubulointerstitial fibrosis, malondialdehyde increase and increases in nuclear factor-kbeta, transforming growth factor-beta, vimentin, inducible NO synthase, and nitrotyrosine expression provoked by CsA. Clodronate did not affect alpha-smooth muscle actin expression and CsA blood levels.

CONCLUSIONS

Renal macrophage influx plays an important role in CsA-induced chronic nephrotoxicity. The NO pathway and oxidative stress are likely mechanisms involved in the genesis of this form of renal injury.

The NRF2-heme oxygenase-1 system modulates cyclosporin A-induced epithelial-mesenchymal transition and renal fibrosis

Epithelial-mesenchymal transition (EMT) is an underlying mechanism of tissue fibrosis, generating myofibroblasts, which serve as the primary source of extracellular matrix production from tissue epithelial cells. Recently, EMT has been implicated in immunosuppressive cyclosporin A (CsA)-induced renal fibrosis. In this study, the potential role of NRF2, which is the master regulator of genes associated with the cellular antioxidant defense system, in CsA-induced EMT renal fibrosis has been investigated. Pretreatment of rat tubular epithelial NRK-52E cells with sulforaphane, an activator of NRF2, could prevent EMT gene changes such as the loss of E-cadherin and the increase in alpha-smooth muscle actin (alpha-SMA) expression. Conversely, genetic inhibition of NRF2 in these cells aggravated changes in CsA-induced EMT markers. These in vitro observations could be confirmed in vivo: CsA treatment resulted in severe renal damage and fibrosis with increased expression of alpha-SMA in NRF2-deficient mice compared to wild-type mice. NRF2-mediated amelioration of CsA-caused EMT changes could be accounted for in part by the regulation of heme oxygenase-1 (HO-1). CsA treatment increased HO-1 expression in an NRF2-dependent manner in NRK cells as well as in murine fibroblasts. Induction of HO-1 by CsA seems to be advantageous in that it counteracts EMT gene changes: specific increase in HO-1 expression caused by cobalt protoporphyrin prevented CsA-mediated alpha-SMA induction, whereas genetic inhibition of HO-1 by siRNA substantially enhanced alpha-SMA induction compared to control cells. Collectively, our results suggest that the NRF2-HO-1 system plays a protective role against CsA-induced renal fibrosis by modulating EMT gene changes.

Polymerized type I collagen reduces chronic cyclosporine nephrotoxicity

BACKGROUND

Polymerized type I collagen (P-collagen) has been successfully used to reduce human hypertrophic scars due to its anti-fibrotic and anti-inflammatory properties. We therefore carried out a study to determine if P-collagen reduces functional and structural injury in chronic cyclosporine [cyclosporine A (CsA)] nephropathy.

METHODS

Four groups of six male Wistar rats fed with a low sodium diet were treated with vehicle, P-collagen (0.8 mg/day, i.p.), CsA (15 mg/kg) or CsA + P-collagen for 15 days. Mean arterial pressure, renal blood flow and glomerular filtration rate were measured in all groups. Structural injury such as arteriolopathy, tubulo-interstitial fibrosis (TI-fibrosis) and positive apoptotic cells were quantified. The mRNA expression levels of transforming growth factor-beta (TGF-beta), kidney injury molecule (Kim-1), alpha-smooth muscle actin (alpha-SMA), glutathione peroxidase, catalase and Cu/Zn superoxide dismutase (SOD) as well as MnSOD were assessed. Antioxidant enzyme activity, renal lipoperoxidation and urinary excretion of oxygen peroxide (UH(2)O(2)V) were determined.

RESULTS

Cyclosporine produced renal dysfunction and induced the development of arteriolopathy, TI-fibrosis and tubular apoptosis. These alterations were associated with increases in TGF-beta, Kim-1 and alpha-SMA mRNA levels as well as with a significant increase of oxidative stress and a reduction of SOD activity. P-Collagen partially ameliorated CsA-induced renal dysfunction and structural injury and prevented both tubular apoptosis and increased oxidative stress. This renoprotective effect was found to be associated with a reduction of TGF-beta, Kim-1 and alpha-SMA mRNA levels.

CONCLUSIONS

This study has therefore demonstrated that P-collagen appears to have anti-fibrotic and anti-apoptotic properties and highlights the possibility that the compound might be useful in a strategy to reduce chronic CsA nephrotoxicity.

Early alterations in protein and gene expression in rat kidney following bromate exposure

Bromate, a common disinfectant byproduct of drinking water ozonation, has been linked to human and animal renal toxicity, including renal cell carcinomas in multiple animal species. Here, we evaluate changes in protein and gene expression through two-dimensional difference gel electrophoresis (2D-DIGE) and Affymetrix arrays to identify potential modes of action involved in potassium bromate carcinogenicity. Male rats were exposed to potassium bromate in drinking water at concentrations of 0, 1, 20 and 400 ppm for two weeks. Differential expression of glycolytic proteins including enolase 1 (Eno1), triosephosphate isomerase 1 (Tpi1) and glyceraldehyde-3-phosphate dehydrogenase (Gapdh) suggests that bromate toxicity is associated with changes in energy consumption and utilization in renal cells involving up-regulation of glycolytic processes that may be the result of altered mitochondrial function. Several alterations in glycolysis and mitochondrial gene transcripts were also observed to be consistent with this mode of action. These studies provide insight into early events in renal cell physiology altered by bromate exposure.

Attenuation of Cyclosporine-Induced Renal Dysfunction by Catechin: Possible Antioxidant Mechanism

One of great use of immunosuppressant, Cyclosporine-A (CsA) is in the solid organ transplantation; however the extensive use of this is cautionable due to its toxic effect in renal tissue, characterized by the tubular atrophy, interstitial fibrosis, and progressive renal impairment. However, there are many mediators are associated with pathogenesis of nephrotoxicity of CsA, the exact mechanism is still in debate. Recent studies indicate that Reactive Oxygen Species (ROS) induced oxidative stress and lipid peroxidations are the important mechanisms implicated in the pathophysiology of nephrotoxicity with CsA. In the present study we examined effect of dietary flavonoid catechin on oxidative damage in cyclosporine-A induced nephrotoxicity. Chronic administration of CsA (20 mg/kg/day) subcutaneously for 21 days significantly decreased the body weight as compared with vehicle treated rats. CsA (20 mg/kg/day) administration for 21 days significantly decreased the renal function by increase in the serum creatinine, blood urea nitrogen, and decrease in the creatinine and urea clearance as compared with vehicle treated rats. Catechin (100 mg/kg/day) for 21 days along with CsA significantly reversed the changed renal parameters, however lower dose of catechin (50 mg/kg/day) restored only increased serum creatinine levels as compared with CsA alone treated group. Biochemical analysis revealed that chronic administration of CsA (20 mg/kg/day) for 21 days significantly induced lipid peroxidation and decreased the glutathione levels in the kidney homogenate of rats. It is also observed that chronic CsA administered rats showed decrease in antioxidant defense enzyme superoxide dismutase and increase in the catalase activity as compared with vehicle treated rats. Co-administration of catechin (100 mg/kg/day) orally along with CsA for 21 days significantly reduced the lipid peroxidation and restored the decreased glutathione levels as compared with CsA alone group, but lower dose of catechin (50 mg/kg/day) restored only decreased glutathione levels induced by CsA. Co-administration of only higher dose of catechin (100 mg/kg/day) along with CsA significantly increased the superoxide dismutase (SOD) levels as compared with CsA alone treated group. It is also observed that catechin (100 mg/kg/day) along with CsA further increased the catalase levels as compared with CsA alone treated group, but not with lower dose of catechin. Animals administered with catechin (100 mg/kg/day) alone for 21 days showed significant increase in the catalase levels as compared with vehicle treated group. The major findings of the present study suggest that oxidative stress might play a significant role in CsA-induced nephrotoxicity. In conclusion, dietary administration of flavonoid catechin could be a useful component for the prevention/treatment of CsA-induced nephrotoxicity.

Calcineurin inhibitor nephrotoxicity

The use of the calcineurin inhibitors cyclosporine and tacrolimus led to major advances in the field of transplantation, with excellent short-term outcome. However, the chronic nephrotoxicity of these drugs is the Achilles' heel of current immunosuppressive regimens. In this review, the authors summarize the clinical features and histologic appearance of both acute and chronic calcineurin inhibitor nephrotoxicity in renal and nonrenal transplantation, together with the pitfalls in its diagnosis. The authors also review the available literature on the physiologic and molecular mechanisms underlying acute and chronic calcineurin inhibitor nephrotoxicity, and demonstrate that its development is related to both reversible alterations and irreversible damage to all compartments of the kidneys, including glomeruli, arterioles, and tubulo-interstitium. The main question--whether nephrotoxicity is secondary to the actions of cyclosporine and tacrolimus on the calcineurin-NFAT pathway--remains largely unanswered. The authors critically review the current evidence relating systemic blood levels of cyclosporine and tacrolimus to calcineurin inhibitor nephrotoxicity, and summarize the data suggesting that local exposure to cyclosporine or tacrolimus could be more important than systemic exposure. Finally, other local susceptibility factors for calcineurin inhibitor nephrotoxicity are reviewed, including variability in P-glycoprotein and CYP3A4/5 expression or activity, older kidney age, salt depletion, the use of nonsteroidal anti-inflammatory drugs, and genetic polymorphisms in genes like TGF-beta and ACE. Better insight into the mechanisms underlying calcineurin inhibitor nephrotoxicity might pave the way toward more targeted therapy or prevention of calcineurin inhibitor nephrotoxicity.

Protective effect of Epo on oxidative renal injury in rats with cyclosporine nephrotoxicity

The aim of our study was to determine the effect of recombinant human erythropoietin (rhEPO) on cyclosporine (CsA) nephrotoxicity. Twenty-six female Wistar rats were injected with 15 mg/kg subcutaneous CsA and intraperitoneal saline/rhEPO for 28 days. Four groups were formed: Group 1 (n = 5), a control group; Group 2 (n = 7), CsA + saline; Group 3 (n = 7), CsA + low dose (20 U/kg per day) rhEPO; Group 4 (n = 7), CsA + high dose (100 U/kg per day) rhEPO. Body weights, creatinine clearance, urinary protein/creatinine, hematocrit, serum creatinine levels, histopathological parameters, apoptosis and lipid peroxidation tests were compared between the three groups. Body weights and renal functions were similar in Groups 2, 3 and 4 rats but significantly lower than the values found for the control group at the end of the study. The hematocrit was significantly different between the four groups, showing a positive association with the strength of the injected rhEPO doses. Tubular and arteriolar damage was significantly lower in Groups 3 and 4 rats than in Group 2 rats, while chronic changes were similar between the three groups. TUNEL-positive cells and thiobabarbituric acid reacting substance (TBARS) levels were significantly higher in Group 2 rats, whereas superoxide dismutase levels were significantly lower in Group 2 rats than in those of the other three groups. Low or high dose rhEPO had no significant protective effects on body weight, renal functions, chronic fibrotic changes, but both doses reduced tubular and arteriolar changes, apoptotis and oxidative stress.

Hyperbaric oxygen treatment improves GFR in rats with ischaemia/reperfusion renal injury: a possible role for the antioxidant/oxidant balance in the ischaemic kidney

BACKGROUND

Ischaemic kidney injury continues to play a dominant role in the pathogenesis of acute renal failure (ARF) in many surgical and medical settings. A major event in the induction of renal injury is related to the generation of oxygen-free radicals. Hyperbaric oxygen therapy (HBO) is indicated for treatment of many ischaemic events but not for ARF. Therefore, the present study examined the effects of HBO on kidney function and renal haemodynamics in rats with ischaemic ARF.

METHODS

Renal ischaemia was induced by unilateral renal artery clamping (45 min) in rats. Within 24 h following ischaemia, rats were treated twice with HBO of 100% O(2) at 2.5 absolute atmospheres for 90 min each (+HBO). Untreated rats (-HBO) served as a control. Forty-eight hours later, GFR, RBF and endothelial-dependent vasorelaxation were measured. In addition, the immunoreactive staining of 4-hydroxy-2-noneal (4-HNE), a major product of endogenous lipid peroxidation, and superoxide dismutase (SOD) were assessed.

RESULTS

In the -HBO group, GFR was reduced by 94% compared with the untouched normal kidney (ischaemic: 0.06 +/- 0.03 ml/min, normal: 1.02 +/- 0.13 ml). In contrast, in the +HBO group, GFR of the ischaemic kidney (0.36 +/- 0.07 ml/min) was reduced only by 68% compared with the contralateral normal kidney (1.12 +/- 0.12 ml/min). In line with these findings, HBO improved the vasodilatory response to ACh as expressed in enhancement of both total and regional renal blood flow. In addition, HBO reduced the formation of 4-HNE by 33% and 76% and increased SOD by 30% and 70% in the cortex and outer stripe region of the medulla of the ischaemic kidney, respectively.

CONCLUSION

HBO attenuates the decline in GFR following renal ischaemia, and improves endothelial-dependent vasorelaxation, suggesting that treatment with HBO may be beneficial in the setting of ischaemic ARF.

Hydrogen sulphide-induced hypothermia attenuates stress-related ulceration in rats

1. Hydrogen sulphide (H(2)S) acts as a gaseous cellular messenger and has recently been reported to induce a suspended animation-like state in mice. The aim of the present study was to investigate the protective role of H(2)S exposure in stress gastric ulcer. 2. In the present study, we used a rat model of water immersion and restraint stress (WRS) to induce the typical stress disease, namely stress gastric ulcer. Rats were treated with WRS for 4 h, with or without pre-exposure to H(2)S (160 p.p.m. H(2)S for 2.5 h). 3. In H(2)S-exposed rats, body temperature was significantly reduced by 2.5C (P < 0.01) and oxygen consumption was reduced by 37.1% (P < 0.01) compared with control rats. Plasma levels of H(2)S were increased by 20.8% (P < 0.01) following pre-exposure. Pre-exposure to H(2)S significantly reduced the gastric ulcer index, from 24 +/- 9 to 9 +/- 2 (P < 0.01), in WRS rats. In addition, WRS increased plasma levels of adrenocorticotropin (ACTH) and corticosterone 4.7- and 4.8-fold, respectively (both P < 0.01). Pre-exposure to H(2)S markedly suppressed plasma ACTH and corticosterone level by 34.4 and 53.2%, respectively (both P < 0.01), and reduced WRS-elevated myeloperoxidase (MPO) activity by 19%. In the present study, WRS increased gastric malondialdehyde and conjugated diene content by 42 and 68%, respectively (both P < 0.01), and H(2)S exposure reduced lipid peroxide production. Finally, H(2)S exposure inhibited the WRS-elevated expression of glucose-regulated protein 78 and caspase 12, markers of endoplasmic reticulum stress. 4. In conclusion, a low concentration of H(2)S may be a new pharmacological tool for induced hypothermia to prevent severe stress-induced diseases and multifarious trauma in the clinical setting.

The protective effect of erdosteine against cyclosporine A-induced cardiotoxicity in rats

Cyclosporine A (CsA) is a frequently used immunosuppressive agent in transplant medicine to prevent rejection and in the treatment of autoimmune diseases. However, CsA generates reactive oxygen species, which causes nephrotoxicity, hepatotoxicity and cardiotoxicity. The use of antioxidants reduces the adverse effects of CsA. The aim of this study is to determine the protective effects of erdosteine on CsA-induced heart injury through tissue oxidant/antioxidant parameters and light microscopic evaluation in rats. CsA cardiotoxicity was induced by administrating an oral dose of 15mg/kg CsA daily for 21 days. The rats were divided into four groups: control group (n=4), CsA administrated group (15mg/kg, n=5), CsA+erdosteine administrated group (10mg/kg day orally erdosteine, n=4) and only erdosteine administrated group (10mg/kg day orally n=5). CsA treated rats showed increase in the number of infiltrated cells and disorganization of myocardial fibers with interstitial fibrosis. The number of infiltrated cells, disorganization of myocardial fibers and interstitial fibrosis was diminished in the hearts of CsA-treated rats given erdosteine. The malondialdehyde, the protein carbonyl content and nitric oxide levels were increased in the cyclosporine A group in comparison with the control and CsA plus erdosteine groups. The activities of superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GSH-Px) were higher in CsA plus erdosteine group than CsA group. However, the CAT, GSH-Px and SOD activities were significantly lower in CsA group than in control group and erdosteine group. These results suggest that erdosteine has protective effect against CsA-induced cardiotoxicity.

Sulphated polysaccharides: new insight in the prevention of cyclosporine A-induced glomerular injury

The scope of the current study was to examine the possible effects of sulphated polysaccharides against cyclosporine A-induced glomerular injury. Nephrotoxicity induced by cyclosporine A continues to be a major problem despite its potent immunosuppressive action. Adult male albino rats of Wistar strain were categorized into four groups. Two groups (II and IV) were administered cyclosporine A (25 mg/kg body weight, orally) for 21 days, in which Group IV rats were also treated simultaneously with sulphated polysaccharides (5 mg/kg body weight, subcutaneously) for the same period. A significant loss in body weight was noted in the cyclosporine A-induced rats. Renal damage was assessed in terms of decreased creatinine clearance and increased activity of lysosomal enzymes. The levels of glycoproteins were found to be decreased in the renal tissue, and a noticeable rise in glycosaminoglycanuria coupled with marked proteinuria was more prominent in the cyclosporine A-induced animals. Furthermore, the extent of kidney damage was assessed by histopathological findings. Toxic manifestations were also confirmed by transmission electron microscopic studies. These morphological abnormalities and other alterations in the renal tissue were significantly offset by sulphated polysaccharides supplementation. These findings underline that restoration of normal cells accredits sulphated polysaccharides, from Sargassum wightii, with nephroprotective role, against cyclosporine A-induced renal injury.

Protective effects of caffeic acid phenethyl ester, vitamin C, vitamin E and N-acetylcysteine on vancomycin-induced nephrotoxicity in rats

The objective of this study was to compare the beneficial effects of caffeic acid phenethyl ester (CAPE), vitamin C, vitamin E and N-acetylcysteine on vancomycin-induced nephrotoxicity. Thirty rats were randomly devided into six groups: (i) control; (ii) vancomycin, 200 mg/kg administrated via intraperitoneal route; (iii) vancomycin plus CAPE-vancomycin with 10 micromol/kg CAPE; (iv) vancomycin plus vitamin C-vancomycin (intraperitoneally) with 200 mg/dl vitamin C in drinking water; (v) vancomycin plus vitamin E-vancomycin with 1000 mg/kg body weight vitamin E (intramuscularly); and (vi) vancomycin plus N-acetylcysteine-vancomycin with 10 mg/kg body weight (intraperitoneally) of N-acetylcysteine. Vancomycin treatments were started 1 day after the first administrations of these agents and continued for 7 days. At the end of the experiments, catalase activity was significantly decreased by vancomycin in kidney homogenates (P < 0.05). Vitamin E, vitamin C, N-acetylcysteine and CAPE administrations decreased the blood urea nitrogen levels increased by vancomycin, although significant differences were detected only in the vitamins E and C groups (P < 0.05). Increased renal malondialdehyde and nitric oxide levels by vancomycin were significantly suppressed by agents used in the study (P < 0.05). Histopathological examination demonstrated prominent damages in the vancomycin-treated group. Vitamin E was the most beneficial agent on vancomycin-induced tubular damage, followed by vitamin C, N-acetylcysteine and CAPE treatments, respectively. The data suggest that vitamin E, as well as vitamin C, N-acetylcysteine and CAPE, could be useful for reducing the detrimental effects on vancomycin-induced toxicity in kidneys.

Cyclosporin A-induced oxidative stress is not the consequence of an increase in mitochondrial membrane potential

Cyclosporin A induces closure of the mitochondrial permeability transition pore. We aimed to investigate whether this closure results in concomitant increases in mitochondrial membrane potential (DeltaPsim) and the production of reactive oxygen species. Fluorescent probes were used to assess DeltaPsim (JC-1, 5,5',6,6'-tetrachloro-1,1',3,3'-tetraethyl-benzimidazolyl-carbocyanine iodide), reactive oxygen species [DCF, 5- (and 6)-chloromethyl-2',7'-dichlorodihydrofluorescein diacetate, acetyl ester] and [Ca2+][Fluo-3, glycine N-[4-[6-[(acetyloxy)methoxy]-2,7-dichloro-3-oxo-3H-xanthen-9-yl]-2-[2-[2-[bis[2-[(acetyloxy)methoxy]-2-oxyethyl]amino]-5-methylphenoxy]ethoxy]phenyl]-N-[2-[(acetyloxy)methoxy]-2-oxyethyl]-(acetyloxy)methyl ester] in human kidney cells (HK-2 cells) and in a line of human small cell carcinoma cells (GLC4 cells), because these do not express cyclosporin A-sensitive P-glycoprotein. We used transfected GLC4 cells expressing P-glycoprotein as control for GLC4 cells. NIM811 (N-methyl-4-isoleucine-cyclosporin) and PSC833 (SDZ-PSC833) were applied as selective mitochondrial permeability transition pore and P-glycoprotein blockers, respectively. To study the effect of cyclosporin A on mitochondrial function, we isolated mitochondria from fresh pig livers. Cyclosporin A and PSC833 induced a more than two-fold increase in JC-1 fluorescence in HK-2 cells, whereas NIM811 had no effect. None of the three substances induced a significant increase in JC-1 fluorescence in GLC4 cells. Despite this, cyclosporin A, NIM811 and PSC833 induced a 1.5-fold increase in DCF fluorescence (P<0.05) and a two-fold increase in Fluo-3 fluorescence (P<0.05). Studies in isolated mitochondria showed that blockage of mitochondrial permeability transition pores by cyclosporin A affected neither DeltaPsim, ATP synthesis, nor respiration rate. The mitochondrial permeability transition pore blockers cyclosporin A and NIM811, but also the non-mitochondrial permeability transition pore blocker PSC833, induced comparable degrees of reactive oxygen species production and cytosolic [Ca2+]. Neither mitochondria, effects on P-glycoprotein nor inhibition of calcineurin therefore play a role in cyclosporin A-induced oxidative stress and disturbed Ca2+ homeostasis.

Vitamin E in renal therapeutic regiments

Administration of vitamin E in children with immunoglobulin A (IgA) nephropathy, focal segmental glomerulosclerosis (FSGS) and type I diabetes demonstrated potential towards ameliorating progression. Oral vitamin E therapy reduced endothelial dysfunction, lipid peroxidation and oxidative stress in patients with chronic kidney failure (CKF). Moreover, the use of vitamin E-bonded hemodialyzers reduced atherosclerotic changes, erythropoietin dosage and muscular cramps in patients on hemodialysis (HD). However, several controlled clinical trials failed to document beneficial effects on the study subjects' cardiovascular and renal outcomes. A recent report of increased all-cause mortality in adult patients receiving high dose vitamin E therapy has caused considerable concern and debate. These issues regarding the efficacy and safety of vitamin E in renal therapeutic regimens will be reviewed in this article.

Role of lipoic acid in reducing the oxidative stress induced by cyclosporine A

BACKGROUND

Cyclosporine A (CsA) is the first choice immunosuppressant universally used for the prevention of allograft rejection in solid organ transplantation and immune-mediated diseases. However, with increasing use, evidence has accumulated that CsA therapy is associated with a variety of side effects, the most important being nephrotoxicity. We investigated the potential role of DL-alpha lipoic acid (LA), a universal antioxidant in combating the oxidative stress induced by CsA.

METHODS

Adult male albino Wistar rats were divided into 4 treatment groups. Two groups received CsA (25 mg/kg body weight, orally for 21 days) to induce nephrotoxicity. One of these groups received LA treatment (20 mg/kg body weight, orally) for 21 days concurrently during CsA administration. A vehicle treated control group and a LA drug control were also included.

RESULTS

CsA-induced nephrotoxicity was assessed in terms of increased activities of serum marker enzymes; alkaline phosphatase, acid phosphatase and lactate dehydrogenase. An apparent rise in the activities of N-acetyl-beta-D-glucosaminidase, beta-glucuronidase and cathepsin D were seen in the renal tissue of CsA given rats, which were reversed upon treatment with LA. CsA administration induced significant elevation in lipid peroxidation along with abnormal levels of enzymic (superoxide dismutase, catalase, glutathione peroxidase, glutathione reductase, glutathione-S-transferase and glucose-6-phosphate dehydrogenase) and non-enzymic antioxidants (glutathione, vitamins C and E) in the rat kidney. LA administration improved renal function, by bringing about a significant decrease in peroxidative levels and increase in antioxidant status.

CONCLUSION

These results indicate that LA has a protective action against CsA nephrotoxicity and suggest that the LA may find clinical application against a variety of toxins where cellular damage is a consequence of reactive oxygen species.

Evidence that intracellular cyclophilin A and cyclophilin A/CD147 receptor-mediated ERK1/2 signalling can protect neurons against in vitro oxidative and ischemic injury

We previously reported that cyclophilin A protein is up-regulated in cortical neuronal cultures following several preconditioning treatments. In the present study, we have demonstrated that adenoviral-mediated over-expression of cyclophilin A in rat cortical neuronal cultures can protect neurons from oxidative stress (induced by cumene hydroperoxide) and in vitro ischemia (induced by oxygen glucose deprivation). We subsequently demonstrated that cultured neurons, but not astrocytes, express the recently identified putative cyclophilin A receptor, CD147 (also called neurothelin, basigin and EMMPRIN), and that administration of purified cyclophilin A protein to neuronal cultures induces a rapid but transient phosphorylation of the extracellular signal-regulated kinase (ERK) 1/2. Furthermore, administration of purified cyclophilin A protein to neuronal cultures protects neurons from oxidative stress and in vitro ischemia. Interestingly, we detected up-regulation of cyclophilin A mRNA, but not protein in the hippocampus following a 3-min period of sublethal global cerebral ischemia in the rat. Despite our in vivo findings, our in vitro data show that cyclophilin A has both intracellular- and extracellular-mediated neuroprotective mechanisms. To this end, we propose cyclophilin A's extracellular-mediated neuroprotection occurs via CD147 receptor signalling, possibly by activation of ERK1/2 pro-survival pathways. Further characterization of cyclophilin A's neuroprotective mechanisms may aid the development of a neuroprotective therapy.

Paraoxonase activity and antibodies to oxidized-LDL in chronic renal failure patients on renal replacement therapy

Serum paraoxonase (PON1) and antibodies to oxidized-LDL (anti ox-LDL) were measured in chronic renal failure subjects on renal replacement therapy such as hemodialysis (HD) peritoneal dialysis (PD) and transplantation (Txp). Paraoxonase activity was significantly lower in HD and PD group (P<0.001) than in control subjects. In transplant patients, paraoxonase activity was not significantly different from that of controls. Antibodies to ox-LDL was significantly higher in HD, PD and Transplant patients (P<0.0001) compared to control subjects. High titers of antibodies were observed in the HD group compared to the PD and Transplant subjects. A decrease in paraoxonase activity and high titers of Antibodies to ox-LDL in the dialysis group suggest a decreased cardio protective effect of HDL and enhanced risk of premature cardiovascular complications. Whereas in case of transplant subjects, there seems to be restoration of PON1 activity, but elevated levels of anti-oxLDL could still be a potential atherogenic factor. Hence, we propose that estimation of these two parameters can be used as a useful index to measure the cardiac risk in the above patient category.

Cyclosporine A induced changes to plasma and erythrocyte antioxidant defences

Organ transplant recipients develop pronounced cardiovascular disease, and decreased antioxidant capacity in plasma and erythrocytes is associated with the pathogenesis of this disease. These experiments tested the hypothesis that the immunosuppressant cyclosporine A (CsA) alters erythrocyte redox balance and reduces plasma antioxidant capacity. Female Sprague-Dawley rats were randomly assigned to a control or CsA treated group. Treatment animals received 25 mg/kg/day of CsA via intraperitoneal injection for 18 days. Control rats were injected with the same volume of the vehicle. Three hours after the final CsA injection, rats were exsanguinated and plasma analysed for total antioxidant status (TAS), alpha-tocopherol, malondialdehyde (MDA), and creatinine. Erythrocytes were analysed for superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPX) and glucose-6-phosphate dehydrogenase (G6PD) activities, alpha-tocopherol, and MDA. CsA administration resulted in a significant (P < 0.05) decrease in plasma TAS and significant increases (P < 0.05) in plasma creatinine and MDA. Erythrocyte CAT was significantly (P < 0.05) increased in CsA treated rats compared to controls. There were no significant differences (P > 0.05) in erythrocyte SOD, GPX, G6PD, alpha-tocopherol or MDA between groups. In summary, CsA alters erythrocyte antioxidant defence and decreases plasma total antioxidant capacity.

Investigation of the Effect of Hyperbaric Oxygen on Experimental Cyclosporine Nephrotoxicity

Hyperbaric oxygen interacts with drugs which patients use concurrently with hyperbaric oxygen treatment, which may cause in potentiation or inhibition of both therapeutic and toxic effects. We examined the effect of hyperbaric oxygen therapy on experimental cyclosporine A nephrotoxicity. The study comprised four groups of rats: a control group, a cyclosporine A group (25 mg/kg/day intraperitoneally for four days), a hyperbaric oxygen group (60 min. every day for four days at 2.5 atmospheric pressure), and a cyclosporine A+hyperbaric oxygen group (CsA 25 mg/kg/day intraperitoneally for four days+hyperbaric oxygen for 60 min. every day for four days at 2.5 atmospheric pressure). Hyperbaric oxygen did not alter biochemical parameters. Cyclosporine A increased serum urea and serum creatinine levels and decreased creatinine clearance. In the cyclosporine A+hyperbaric oxygen group serum urea level increased more than in the cyclosporine A group. Cyclosporine A increased tubular epithelial cell apoptosis and necrosis score values. The numbers of apoptotic cells in proximal tubule epithelial cells in the cyclosporine A+hyperbaric oxygen group were significantly higher than those of the cyclosporine A group. We recommend that renal functions of the patients receiving cyclosporine A should be monitored during hyperbaric oxygen therapy.

Acute exposure to cyclosporine does not increase plasma homocysteine in rats

There is interest in the postulate that cyclosporine a (CsA) contributes to the elevated homocysteine levels seen in organ transplant recipients, as hyperhomocysteinemia is now considered an independent risk factor for cardiovascular disease (CVD) and may partially explain the increased prevalence of CVD in this population. The main purpose of this investigation was to determine the effect of CsA administration on plasma homocysteine. Eighteen female Sprague Dawley rats (4 months old) were randomly assigned to either a treatment or a control group. For 18 days the treatment group received of CsA (25 mg/kg/d) while the control group received the same volume of the vehicle. Blood samples obtained following sacrifice to measure CsA, total homocysteine, and plasma creatinine. There were no significant differences in plasma homocysteine (mean values +/- SD: treatment = 4.79 +/- 0.63 micromol/L, control = 4.46 +/- 0.75 micromol/L; P = .37). Homocysteine was not significantly correlated with final CsA concentrations (r = .17; P = .69). There was a significant difference in plasma creatinine values between the two groups (treatment = 60.44 +/- 7.68 micromol/L, control = 46.33 +/- 1.66 micromol/L; P < .001). Furthermore, plasma homocysteine and creatinine were positively correlated with the treatment group (r = .73; P < .05) but not the controls (r = -.10; P = .81). In conclusion, CsA does not influence plasma homocysteine concentrations in rats.

Antioxidant supplementation enhances erythrocyte antioxidant status and attenuates cyclosporine-induced vascular dysfunction

The aim of this study was to determine the effects of dietary antioxidant supplementation with alpha-tocopherol and alpha-lipoic acid on cyclosporine-induced alterations to erythrocyte and plasma redox balance, and cyclosporine-induced endothelial and smooth muscle dysfunction. Rats were randomly assigned to either control, antioxidant, cyclosporine or cyclosporine + antioxidant treatments. Cyclosporine A was administered for 10 days after an 8-week feeding period. Plasma was analyzed for alpha-tocopherol, total antioxidant capacity, malondialdehyde and creatinine. Erythrocytes were analyzed for glutathione, methemoglobin, superoxide dismutase, catalase, glutathione peroxidase, glucose-6-phosphate dehydrogenase, alpha-tocopherol and malondialdehye. Vascular endothelial and smooth muscle function was determined in vitro. Antioxidant supplementation resulted in significant increases in erythrocyte alpha-tocopherol concentration and glutathione peroxidase activity in both of the antioxidant-supplemented groups. Cyclosporine administration caused significant decreases in glutathione concentration, methemoglobin concentration and superoxide dismutase activity. Antioxidant supplementation attenuated the cyclosporine-induced decrease in superoxide dismutase activity. Cyclosporine therapy impaired both endothelium-independent and -dependent relaxation of the thoracic aorta, and this was attenuated by antioxidant supplementation. In summary, dietary supplementation with alpha-tocopherol and alpha-lipoic acid attenuated the cyclosporine-induced decrease in erythrocyte superoxide dismutase activity and attenuated cyclosporine-induced vascular dysfunction.