Prevention of nephrotoxicity induced by cyclosporine-A: role of antioxidants

Precision nephrotoxicity testing using 3D in vitro models

Nephrotoxicity is a significant concern during the development of new drugs or when assessing the safety of chemicals in consumer products. Traditional methods for testing nephrotoxicity involve animal models or 2D in vitro cell cultures, the latter of which lack the complexity and functionality of the human kidney. 3D in vitro models are created by culturing human primary kidney cells derived from urine in a 3D microenvironment that mimics the fluid shear stresses of the kidney. Thus, 3D in vitro models provide more accurate and reliable predictions of human nephrotoxicity compared to existing 2D models. In this review, we focus on precision nephrotoxicity testing using 3D in vitro models with human autologous urine-derived kidney cells as a promising approach for evaluating drug safety.

Low dose of cyclosporine A disrupts sperm parameters and testosterone levels reversibly in mice

The prevalence of autoimmune diseases has increased worldwide, including in men of reproductive age. Cyclosporine A (CsA) is an immunosuppressive drug commonly used for long periods in the prophylaxis and treatment of autoimmune dysfunction and transplant rejection. Owing to CsA toxicity, most clinical settings use lower CsA doses. Therefore, we evaluated whether a low dose (10 mg/kg) of CsA affects sperm parameters (daily sperm production, motility, morphology, mitochondrial activity, and acrosomal integrity), plasma testosterone levels, and fertility after short-term (10 days) and long-term (50 days) treatments in mice. Short-term CsA treatment partially affected sperm parameters and fertility, as shown by the reduction in sperm hyperactivation and gestational rate 10 days after the interruption of short-term CsA treatment. Long-term CsA treatment impairs sperm count, hyperactivated motility, and acrosomal integrity. This treatment regimen further decreased plasma testosterone concentrations but did not affect reproductive outcomes in mating trials. These outcomes were reversed 50 days after the interruption of long-term CsA treatment. We conclude that a low CsA dose differentially impairs sperm parameters and testicular steroidogenesis in a time-dependent and mostly reversible manner but does not affect male fertility.

A Synopsis of Current Theories on Drug-Induced Nephrotoxicity

The overriding goal of the treatment of patients is its effectiveness and safety. However, all medications currently being used also exert some adverse pharmaceutical reactions, which may be regarded as an unintended but inevitable cost of pharmacotherapy. The kidney, as the main organ that eliminates xenobiotics, is an organ especially predisposed and vulnerable to the toxic effects of drugs and their metabolites during their excretion from the body. Moreover, some drugs (e.g., aminoglycosides, cyclosporin A, cisplatin, amphotericin B, and others) have a "preferential" nephrotoxicity potential, and their use is associated with an increased risk of kidney damage. Drug nephrotoxicity is, therefore, both a significant problem and a complication of pharmacotherapy. It should be noted that, currently, there is no generally recognized definition of drug-induced nephrotoxicity and no clear criteria for its diagnosis. This review briefly describes the epidemiology and diagnosis of drug-induced nephrotoxicity and characterizes its pathomechanisms, including immunological and inflammatory disturbances, altered kidney blood flow, tubulointerstitial injury, increased lithogenesis-crystal nephropathy, rhabdomyolysis, and thrombotic microangiopathy. The study also lists the basic drugs with nephrotoxicity potential and provides a short overview of the preventive methods for reducing the risk of drug-related kidney damage developing.

Natural Reno-Protective Agents against Cyclosporine A-Induced Nephrotoxicity: An Overview

CA (cyclosporine A) is a powerful immunosuppressing agent that is commonly utilized for treating various autoimmune illnesses and in transplantation surgery. However, its usage has been significantly restricted because of its unwanted effects, including nephrotoxicity. The pathophysiology of CA-induced kidney injury involves inflammation, apoptosis, tubular injury, oxidative stress, and vascular injury. Despite the fact that exact mechanism accountable for CA's effects is inadequately understood, ROS (reactive oxygen species) involvement has been widely proposed. At present, there are no efficient methods or drugs for treating CA-caused kidney damage. It is noteworthy that diverse natural products have been investigated both in vivo and in-vitro for their possible preventive potential in CA-produced nephrotoxicity. Various extracts and natural metabolites have been found to possess a remarkable potential for restoring CA-produced renal damage and oxidative stress alterations via their anti-apoptosis, anti-inflammatory, and antioxidative potentials. The present article reviews the reported studies that assess the protective capacity of natural products, as well as dietary regimens, in relation to CA-induced nephrotoxicity. Thus, the present study presents novel ideas for designing and developing more efficient prophylactic or remedial strategies versus CA passive influences.

Cyclosporine A Induces Cardiac Developmental Toxicity in Zebrafish by Up-Regulation of Wnt Signaling and Oxidative Stress

Due to the widely application of Cyclosporine A (CsA) as an immunosuppressant in clinic, it is necessary to study its potential toxicity. Therefore, we used zebrafish as a model animal to evaluate the toxicity of CsA on embryonic development. Exposure of zebrafish embryos to CsA at concentrations of 5 mg/L, 10 mg/L, and 15 mg/L from 12 hpf to 72 hpf resulted in abnormal embryonic development, including cardiac malformation, pericardial edema, decreased heart rate, decreased blood flow velocity, deposition at yolk sac, shortened body length, and increased distance between venous sinus and arterial bulb (SV-BA). The expression of genes related to cardiac development was disordered, and the apoptotic genes were up-regulated. Oxidative stress level was up-regulated and accumulated in pericardium in a dose-dependent manner. Astaxanthin (ATX) treatment could significantly alleviate zebrafish heart defects. CsA induced up-regulation of Wnt signaling in zebrafish, and IWR-1, an inhibitor of Wnt signaling pathway, could effectively rescue the heart defects induced by CsA. Together, our study indicated that CsA induced cardiac developmental toxicity in zebrafish larvae through up-regulating oxidative stress and Wnt signaling, contributing to a more comprehensive evaluation of the safety of the drug.

The protective effect of resveratrol against cyclosporine A-induced oxidative stress and hepatotoxicity

The immunosuppressive agent cyclosporine A (CsA) has hepatotoxic potential. Increased reactive oxygen species (ROS) formation is among the causes leading to hepatotoxicity. This study aimed to investigate the effect of resveratrol (RES) on CsA-induced oxidative stress and hepatotoxicity in rats. Rats were treated with RES (10 mg/kg/day; i.p.) for 14 days. CsA (25 mg/kg/day; s.c.) was given during the last seven days together with RES. Serum alanine aminotransferase and aspartate aminotransferase activities together with hepatic histopathological examinations were performed. ROS, thiobarbituric acid reactive substances (TBARS), advanced oxidation protein products (AOPPs), ferric reducing antioxidant power, and glutathione levels as well as superoxide dismutase, and glutathione peroxidase activities were measured in the liver tissue. RES ameliorated histopathological changes and decreased hepatic ROS, TBARS, and AOPP levels significantly. However, antioxidant parameters did not change in CsA-treated rats. Our results indicate that RES treatment may be effective in decreasing CsA-induced oxidative stress and hepatotoxicity.

A Novel Dipeptidyl Peptidase-4 Inhibitor DA-1229 Ameliorates Tubulointerstitial Fibrosis in Cyclosporine Nephrotoxicity in Mice

Cyclosporine A (CyA) is an immunosuppressive agent that induces nephrotoxicity with long-term treatment. The roles of DPP-4 and its inhibitors in cyclosporine nephrotoxicity are not fully understood. Therefore, we investigated the effects of a novel DPP-4 inhibitor, DA-1229, on the progression of renal disease in an experimental cyclosporine nephrotoxicity model. Chronic cyclosporine nephrotoxicity was induced in six-week-old male ICR mice by subcutaneous injections of CyA at a dose of 30 mg/kg for four weeks. Animals were treated with DA-1229 at a dose of 300 mg/kg per day in food for four weeks. Although DPP-4 activity did not increase in the kidneys of mice with induced cyclosporine nephrotoxicity, DA-1229 treatment significantly suppressed DPP-4 activity in both plasma and renal tissues. DPP-4 inhibition by DA-1229 led to significantly decreased albuminuria and urinary excretion of 8-isoprosatane. DPP-4 inhibition also substantially suppressed pro-inflammatory effects, profibrotic molecules, and macrophage infiltration, and led to the improvement in renal structural changes. Our results suggest that DPP-4 inhibition by DA-1229 provides renoprotective effects in an animal model of cyclosporine nephrotoxicity via antioxidant, anti-inflammatory, and anti-fibrotic mechanisms. DPP-4 inhibition may be a useful new therapeutic approach for the management of progressive renal disease in cyclosporine nephrotoxicity.

Effect of Kaempferol on Tacrolimus-Induced Nephrotoxicity and Calcineurin B1 Expression Level in Animal Model

BACKGROUND

The kidneys are considered one of the most susceptible organs for adverse drug effects, particularly in post-transplant conditions. Tacrolimus (FK506), a calcineurin inhibitor immunosuppressant, is an essential component in the transplantation regimen. Despite that, nephrotoxicity is a severe drawback for its chronic utilization, where oxidative stress might be implicated. Kaempferol (KMF) is a natural flavonoid that has many adaptable biological activities, including antioxidant action.

OBJECTIVE

Exploring the KMF protective effect on FK506-induced nephrotoxicity and the underlying role of calcineurin B1.

METHODS

Twenty-four male albino-Wistar rats were randomly divided into three equal groups. The control group received solvents: propylene glycol, i.p. and 0.5% carboxymethyl cellulose, PO; FK506 group was injected with FK506 (0.6 mg/kg, i.p.), and FK506+KMF group was given FK506 (0.6 mg/kg, i.p.) and KMF (10 mg/kg, PO). The treatment regimen for all groups was once daily for 30 days. ELISA technique applied for measuring FK506 trough level and nephrotoxicity biomarkers in serum (cystatin C and urea) on days 15 and 30, and in kidney tissue homogenate (MDA and calcineurin B1) on day 30.

RESULTS

In FK506-treated rats, the FK506 trough level was 7.84 ± 1.31 ug/l on day 15 and 9.54 ± 1.45 ug/l on day 30. FK506 use has significantly (P<0.01) increased biomarkers levels of cystatin C (325% and 477%), urea (177% and 245%), MDA (1253%), except calcineurin B1 that has decreased (97%). The KMF combination has resulted in a significant reduction in the FK506 trough level by day 30 (6.79 ± 1.35 ug/l, P<0.01). KMF has significantly ameliorated the levels of cystatin C (46% and 73%, P<0.001), urea (38% and 68%, P<0.001), MDA (75%, P<0.001), and calcineurin B1 (1833%, P<0.05).

CONCLUSION

Oxidative stress and calcineurin B1 are contributing factors in FK506-induced nephrotoxicity. Hence, inhibition of calcineurin enzyme is not limited to the immune cells. KMF could be a novel nephroprotective antioxidant.

Cyclosporine A induces kidney dysfunction by the alteration of molecular mediators involved in slit diaphragm regulation and matrix metalloproteins: the mitigating effect of curcumin

BACKGROUND

This research aimed at investigating the cyclosporine A intake impact with/without curcumin on podocyte protein gene expressions and matrix metalloproteins (MMPs) changes in rat kidney.

METHODS

Thirty-two Wistar male rats were assigned to the control, sham, cyclosporine A, and cyclosporine A with curcumin groups.

RESULTS

A significant increase was observed in CD2AP, ACTN4, podocin and also MMP9 and 2, cystatin C levels in the cyclosporine A group following treatment for four weeks, whereas a decrease was found in nephrin gene expression than the control group. In addition, a significant reduction was observed in the cyclosporine A group in glomerular filtration rate (GFR), urine creatinine, and increased plasma creatinine levels than the control group. Using curcumin plus cyclosporine A ameliorated gene expression alterations and increased the reduced amount of GFR, urine urea, and creatinine while reducing the increased plasma cystatine C, urea, and creatinine levels compared with the cyclosporine A group.

CONCLUSION

Accordingly, cyclosporine A-induced kidney abnormalities are possibly associated with changes in podocyte intra- and extra-cellular protein gene expression that influence the quality of filtrated fluid via altering the foot process shape and slit diaphragm size. Finally, such impacts are reduced via curcumin as an antioxidant and anti-inflammatory compound.

[Role of TGF-β1/ILK/FSP1 signaling pathway in cyclosporin A-induced epithelialmesenchymal transition in cultured renal tubular epithelial cells]

OBJECTIVE

To explore the role of transforming growth factor-β1/integrin-linked kinase/fibroblast-specific protein 1 (TGF- β1/ILK/FSP1) signaling pathway in cyclosporine A (CsA)-induced renal tubular epithelial cell transdifferentiation.

METHODS

Rat renal tubular epithelial NRK-52E cells were induced with 1 mg/L CsA, treated with TGF-β1 inhibitor (SB431542, 10 μmol/L), or transfected with the ILK-RNAi lentiviral expression vector (ILKshRNA) or a negative control vector before CsA induction. The expressions of TGF-β1, ILK and FSP-1 mRNAs and proteins in the cells were detected using real-time PCR and Western blotting. The positive cells for α-SMA expression were detected by immunohistochemistry.

RESULTS

Compared with the blank control cells, the cells treated with CsA showed significantly increased levels of TGF-β1, ILK and FSP-1 mRNAs and proteins (P < 0.05). The expressions of TGF-β1, ILK and FSP-1 were significantly lower in TGF-β1 inhibitor group than in CsA group (P < 0.05). The levels of ILK and FSP-1 were significantly decreased after shRNA-mediated ILK silencing (P < 0.05). The number of positive cells for α-SMA was significantly lower in cells treated with SB431542 and in cells with ILK silencing than in the cells treated with CsA alone (P < 0.05).

CONCLUSIONS

The activation of TGF-β1/ILK/FSP-1 signaling pathway is an important mechanism for CsA-induced transdifferentiation in rat renal tubular epithelial cells. ILK participates in CsA-induced epithelialmesenchymal transition of renal tubular epithelial cells.

Modulation of eNOS/iNOS by nebivolol protects against cyclosporine A-mediated nephrotoxicity through targeting inflammatory and apoptotic pathways

The aim of this study was to investigate effect of nitric oxide (NO) modulation on possible nephroprotective mechanisms of nebivolol (NEB) in cyclosporine A (CsA)-induced nephrotoxicity. Rats were treated with 20 mg/kg/day s.c. of CsA for 21 days, with NEB alone (10 mg/kg/day orally) or together with a NOS inhibitor, L-NAME (10 mg/kg/day i.p.). NEB conferred nephroprotection against CsA-induced toxicity, significantly decreasing serum kidney function tests and improving renal histopathology. NEB showed antioxidant effects, by significantly decreasing renal malondialdehyde levels, while increasing reduced glutathione levels and catalase activity. NEB showed anti-inflammatory and anti-apoptotic effects; reducing renal expression NF-κB and fas ligand. NEB also reversed CsA-induced effects on NO system; increasing renal NO level, with up-regulation of eNOS and down-regulation of iNOS expression. Administering L-NAME with NEB reversed all beneficial effects of NEB. Thus, NEB's modulation of NO system in CsA-induced nephrotoxicity might be the triggering mechanism controlling NEB's nephroprotective effect.

Influence of Tacrolimus on Depressive-Like Behavior in Diabetic Rats Through Brain-Derived Neurotrophic Factor Regulation in the Hippocampus

The neurotoxicity of immunosuppressive agents and diabetes mellitus are known risk factors of neurological complications in kidney transplant recipients. The aim of the present study was to investigate the influence of tacrolimus on brain-derived neurotrophic factor (BDNF), the critical protein for maintenance of neuronal functions, in the hippocampus in a diabetic condition. A diabetic rat model was established by a single streptozotocin injection (60 mg/kg). Control and diabetic rats then received daily tacrolimus (1.5 mg/kg per day) injections for 6 weeks. BDNF expression in the hippocampus was examined in the dentate gyrus (DG) and CA3 region using immunohistochemistry. There was a significant decrease of BDNF expression in the DG and CA3 region in tacrolimus-treated and diabetic rats compared with that of the control group injected with vehicle only. However, there was no difference in BDNF expression between the two experimental groups. Tacrolimus treatment in diabetic rats further decreased the BDNF expression level in the DG and CA3 region. Interestingly, mossy fiber sprouting, demonstrated by prominent punctate immunolabeling of BDNF with synaptoporin, was observed in the diabetic group treated with tacrolimus, which localized at the stratum oriens of the CA3 region. These data suggest that tacrolimus treatment or a diabetic condition decreases BDNF expression in the hippocampus, and that tacrolimus treatment in the diabetic condition further injures the CA3 region of the hippocampus. In addition to BDNF expression, decreased locomotor activity and evident depressive behavior were observed in tacrolimus-treated diabetic rats. Moreover, there were significant decreases of the mRNA levels of γ-aminobutyric acid and serotonin receptors in the diabetic hippocampus with tacrolimus treatment. This finding suggests that tacrolimus treatment may cause further psychiatric and neurological complications for patients with diabetes, and should thus be used with caution.

Metabolic Pathway of Cyclosporine A and Its Correlation with Nephrotoxicity

Background:

Cyclosporine A (CsA) is widely used for organ transplantation and autoimmune disorders. However, CsA nephrotoxicity is a serious side effect that limits the clinical use of CsA. The metabolism of CsA has a close relationship with this disease in renal-transplant patients. However, the metabolic pathways of CsA and its metabolizing enzymes have rarely been comprehensively reviewed. In this review, we have summarized the specific metabolic profiles of CsA in humans, especially renal-transplant patients. Moreover, the specific metabolizing enzymes and the potential roles that CsA metabolism plays in CsA nephrotoxicity were summarized and discussed.

Methods:

Electronic databases including PubMed, Web of Science, and Scifinder were searched with the keywords "Cyclosporine A and metabolism", and "Cyclosporine A and nephrotoxicity", "Cyclosporine A metabolism and nephrotoxicity". All these studies published until 2018 were included in this review.

Results:

The major metabolic pathways of CsA in humans are hydroxylation and N-demethylation. Normally, these metabolites are relatively less toxic than CsA. However, the metabolism of CsA in the kidneys is much weaker than that in the liver, which explains why CsA is so toxic to the kidneys. CYP3A families, especially CYP3A4 and CYP3A5, play an important role in the biotransformation of CsA. Moreover, increased lines of evidence show that some metabolites (including AM19) associate directly with nephrotoxicity in CsA-treated organ-transplant patients.

Conclusion:

The findings of this review help to further understand the metabolic activities of CsA in renal-transplant patients and cast some light on the mechanisms of CsA nephrotoxicity.

Optimal sampling time-point for cyclosporin A concentration monitoring in heart transplant recipients

The present study was performed to determine an optimal time-point for monitoring the concentration of the immunosuppressive drug cyclosporin A (CsA) in heart transplant patients and its efficacy in the prevention of transplant rejection. A total of 32 transplant recipients were randomly assigned for three treatment approaches. Recipients in groups A (n=11), B (n=13) and C (n=8) received oral administration of CsA at doses of 3.2, 3.5 and 4.4 mg/kg, respectively. The plasma CsA concentrations were examined at 2 h intervals over 12 h. Furthermore, their correlation with the 4 h pharmacokinetic profiles as the area under the plasma CsA concentration vs. time curve (AUC_{0-4 h}) were calculated The efficacy of CsA in inhibiting cardiac allograft rejection was assessed at 2 h after oral CsA intake (C2) and adverse events of the drug were examined in the C2-monitored recipients. The plasma CsA concentration rapidly increased in most recipients with a peak level detected at ~2 h after dosing. Regression analysis revealed that among all time-points assessed, the CsA had the highest correlation with the AUC_{0-4 h} at C2. At C2, increasing CsA doses exhibited a positive association with the measure of AUC_{0-4 h}. The efficacy of increasing CsA target levels at C2 in preventing heart transplant rejection was comparable, as the survival rate was 100% in all of the treatment groups. However, the proportion of recipients with side effects in group A was obviously lower than that in the other two groups. In conclusion, C2 is an ideal time-point for monitoring plasma CsA levels with a utility for individualising the next scheduled dose for each patient to ensure that target levels are maintained and achieve a high efficacy and safety of CsA therapy in heart transplant recipients (clinical trial no. 12002610).

Activation of renal profibrotic TGFβ controlled signaling cascades by calcineurin and mTOR inhibitors

The calcineurin inhibitors (CNI) cyclosporine A (CsA) and tacrolimus represent potent immunosuppressive agents frequently used for solid organ transplantation and treatment of autoimmune disorders. Despite of their immense therapeutic benefits, residual fibrosis mainly in the kidney represents a common side effect of long-term therapy with CNI. Regardless of the immunosuppressive action, an increasing body of evidence implicates that a drug-induced increase in TGFβ and subsequent activation of TGFβ-initiated signaling pathways is closely associated with the development and progression of CNI-induced nephropathy. Mechanistically, an increase in reactive oxygen species (ROS) generation due to drug-induced changes in the intracellular redox homeostasis functions as an important trigger of the profibrotic signaling cascades activated under therapy with CNI. Although, inhibitors of the mechanistic target of rapamycin (mTOR) kinase have firmly been established as alternative compounds with a lower nephrotoxic potential, an activation of fibrogenic signaling cascades has been reported for these drugs as well. This review will comprehensively summarize recent advances in the understanding of profibrotic signaling events modulated by these widely used compounds with a specific focus put on mechanisms occurring independent of their respective immunosuppressive action. Herein, the impact of redox modulation, the activation of canonical TGFβ and non-Smad pathways and modulation of autophagy by both classes of immunosuppressive drugs will be highlighted and discussed in a broader perspective. The comprehensive knowledge of profibrotic signaling events specifically accompanying the immunomodulatory activity of these widely used drugs is needed for a reliable benefit-risk assessment under therapeutic regimens.

Cyclosporine A induces endothelin-converting enzyme-1: Studies in vivo and in vitro

AIM

Cyclosporine A (CsA) induces renal vasoconstriction and hypoxia and enhances the expression of endothelin-1 (ET-1) pro-hormone (pre-pro-ET-1), plausibly leading to a feed-forward loop of renal vasoconstriction, hypoxia and enhanced synthesis of the potent vasoconstrictor ET-1. Endothelin-converting enzyme (ECE)-1 cleaves big endothelin to generate endothelin (ET)-1 and is upregulated by hypoxia via hypoxia-inducible factor (HIF). We hypothesized that in addition to the direct induction of ET-1 synthesis, CsA might also intensify renal ECE-1 expression, thus contributing to enhanced ET-1 synthesis following CsA.

METHODS

CsA was administered to Sprague Dawley rats (120 mg/kg/SC) for 4 days, and renal HIF and ECE-1 expression were assessed with Western blots and immunostaining. Human umbilical vein endothelial cells (HUVEC) and proximal tubular cell line (HK-2) were subjected to CsA, and ECE-1 induction was evaluated using real-time mRNA PCR and Western blots.

RESULTS

Cyclosporine A intensified renal parenchymal ECE-1 expression in the rat kidney, particularly in distal nephron segments, along with renal hypoxia (detected by pimonidazole adducts) and HIF expression, in line with our recent observations showing episodic hypoxia in mice subjected to CsA. Furthermore, in cultured normoxic HUVEC and HK-2 cells, CsA dose-dependently induced both pre-pro-ET-1 and ECE-1 mRNA and protein expression, with enhanced ET-1 generation.

CONCLUSION

CsA induces ECE-1 via both hypoxic and non-hypoxic pathways. ECE-1 may contribute to increased renal ET-1 generation following CsA, participating in a feed-forward loop of renal parenchymal hypoxia and ET synthesis.

Endothelin-1 receptor antagonists protect the kidney against the nephrotoxicity induced by cyclosporine-A in normotensive and hypertensive rats

Cyclosporin-A (CsA) is an immunosuppressant associated with acute kidney injury and chronic kidney disease. Nephrotoxicity associated with CsA involves the increase in afferent and efferent arteriole resistance, decreased renal blood flow (RBF) and glomerular filtration. The aim of this study was to evaluate the effect of Endothelin-1 (ET-1) receptor blockade with bosentan (BOS) and macitentan (MAC) antagonists on altered renal function induced by CsA in normotensive and hypertensive animals. Wistar and genetically hypertensive rats (SHR) were separated into control group, CsA group that received intraperitoneal injections of CsA (40 mg/kg) for 15 days, CsA+BOS and CsA+MAC that received CsA and BOS (5 mg/kg) or MAC (25 mg/kg) by gavage for 15 days. Plasma creatinine and urea, mean arterial pressure (MAP), RBF and renal vascular resistance (RVR), and immunohistochemistry for ET-1 in the kidney cortex were measured. CsA decreased renal function, as shown by increased creatinine and urea. There was a decrease in RBF and an increase in MAP and RVR in normotensive and hypertensive animals. These effects were partially reversed by ET-1 antagonists, especially in SHR where increased ET-1 production was observed in the kidney. Most MAC effects were similar to BOS, but BOS seemed to be better at reversing cyclosporine-induced changes in renal function in hypertensive animals. The results of this work suggested the direct participation of ET-1 in renal hemodynamics changes induced by cyclosporin in normotensive and hypertensive rats. The antagonists of ET-1 MAC and BOS reversed part of these effects.

miR-181c protects CsA-induced renal damage and fibrosis through inhibiting EMT

Cyclosporine A (CsA), a widely used immunosuppressive drug in organ transplantation and autoimmune disorders, frequently induces renal damage and fibrosis. Recent evidence has implicated epithelial-mesenchymal transition (EMT) in CsA-induced nephrotoxicity. Microarray analysis disclosed miR-181c as the microRNA most dramatically repressed by CsA. Downregulation of miR-181c expression at the transcriptional level by CsA is dependent on the transcription factor Nrf2. miR-181c mimics or inhibitors attenuate or aggravate CsA-induced EMT gene changes, respectively. Importantly, in Nrf2-/- mice, CsA-induced renal damage, fibrosis, and EMT gene changes are restored by miR-181c mimics. Mechanistically, we identified Notch2 as a potential target of miR-181c. Collectively, our data support the notion that miR-181c may serve as an important factor for protecting renal tissues from CsA-induced nephrotoxicity.

Attenuation of cyclosporine A induced nephrotoxicity by schisandrin B through suppression of oxidative stress, apoptosis and autophagy

Cyclosporine A (CsA) is a potent immunosuppressive agent whose clinical usage is limited by nephrotoxicity. Schisandrin B (SchB), isolated from the fruit of Schisandra chinensis, is a natural compound with multiple pharmacological activities that has been shown to attenuate organ injury caused by CsA. Hence, the primary objective of the current study was to evaluate whether SchB has a cytoprotective effect on CsA-induced nephrotoxicity in human proximal tubular epithelial cell line (HK-2). This study demonstrated that pre-incubation of HK-2 cells with 2.5-10.0μM SchB ameliorated CsA induced cytotoxicity caused by oxidative stress as evidenced by reduced levels of intracellular reactive oxygen species (ROS) and LDH release along with increased levels of mitochondrial membrane potential (ΔΨm) and glutathione (GSH). Also, it was demonstrated that nuclear factor erythroid 2-related factor 2 (Nrf2) activation was involved in modulating cellular oxidative stress, where SchB promoted Nrf2 translocation into the nucleus and downstream target gene expression of heme oxygenase-1 (HO-1), NAD(P)H:quinone oxidoreductase 1 (NQO1) and Glutamate-cysteine ligase modifier subunit (GCLM). Additionally, SchB was found to enhance cell survival via reducing apoptosis rate as well as recover the CsA induced blockade of autophagic flux. Collectively, these findings demonstrated that SchB mediated alleviation of CsA induced nephrotoxicity by preventing the accumulation of ROS by way of suppressing oxidative stress, apoptosis and autophagy.

Protective Effect of Edaravone Against Cyclosporine-Induced Chronic Nephropathy Through Antioxidant and Nitric Oxide Modulating Pathways in Rats

BACKGROUND

Cyclosporine A (CsA) is an immunosuppressant with therapeutic indications in various immunological diseases; however, its use is associated with chronic nephropathy. Oxidative stress has a crucial role in CsA-induced nephrotoxicity. The present study evaluates the protective effect of edaravone on CsA-induced chronic nephropathy and investigates its antioxidant and nitric oxide modulating property.

METHODS

Male Sprague-Dawley rats (n=66) were distributed into nine groups, including a control (group 1) (n=7). Eight groups received CsA (15 mg/kg) for 28 days while being treated. The groups were categorized as: Group 2: Vehicle (n=10)Groups 3, 4, and 5: Edaravone (1, 5, and 10 mg/kg) (n=7 each)Group 6: Diphenyliodonium chloride, a specific endothelial nitric oxide synthase (eNOS) inhibitor (n=7)Group 7: Aminoguanidine, a specific inducible nitric oxide synthase (iNOS) inhibitor (n=7)Group 8: Edaravone (10 mg/kg) plus diphenyliodonium chloride (n=7)Group 9: Edaravone (10 mg/kg) plus aminoguanidine (n=7) Blood urea nitrogen and serum creatinine levels, malondialdehyde, superoxide dismutase, and glutathione reductase enzyme activities were measured using standard kits. Renal histopathological evaluations and measurements of eNOS and iNOS gene expressions by RT-PCR were also performed. Data were analyzed using one-way analysis of variance (ANOVA) followed by Tukey's test (SPSS software version 18.0).

RESULTS

Edaravone (10 mg/kg) significantly attenuated CsA-induced oxidative stress, renal dysfunction, and kidney tissue injury. Aminoguanidine improved the renoprotective effect of edaravone. Edaravone reduced the elevated mRNA level of iNOS, but could not alter the level of eNOS mRNA significantly.

CONCLUSION

Edaravone protects against CsA-induced chronic nephropathy using antioxidant property and probably through inhibiting iNOS gene expression.

The Protective Effect of Febuxostat on Chronic Tacrolimus-Induced Nephrotoxicity in Rats

BACKGROUND

The use of calcineurin inhibitors is a well-known risk factor for hyperuricemia in kidney transplant recipients. We evaluated the effect of febuxostat (Fx), a new uric acid-lowering drug, on hyperuricemia and renal injury in an experimental model of chronic tacrolimus (Tac)-induced nephropathy.

METHODS

Chronic Tac nephropathy was induced by administering Tac (1.5 mg/kg/day) to rats on a low-salt diet (0.05%) with oxonic acid (OA, 2%, 0.2 g/kg/day) for 28 days. Two doses of Fx (5 and 10 mg/kg) were concomitantly administered with Tac or vehicle (Vh). We evaluated the effect of Fx on hyperuricemia by measuring serum uric acid (SUA) levels, fractional excretion of uric acid (FEUA), and urate transporters in Tac-induced nephropathy. The effects of Fx on Tac-induced renal injury were evaluated in terms of renal function and arteriolopathy, tubulointerstitial fibrosis, inflammation, and apoptosis. We evaluated oxidative stress as a protective mechanism via xanthine oxidase (XO) activity, and as a marker of oxidative stress (via evaluation of levels of 8-hydroxy-2'-deoxyguanosine (8-OHdG) and 4-hydroxy-2-hexenal (4-HHE)).

RESULTS

The Tac group showed higher SUA levels and lower FEUA than did the Vh group, but Fx treatment significantly decreased SUA levels in a dose-dependent manner, with an increase of FEUA at a high dose (10 mg/kg). Tac treatment increased urate-anion exchanger 1 and decreased organic anion transporter type 1 expression in renal tubular cells, but Fx treatment reversed the effects on those transporters. Impaired renal function and histological injury (interstitial fibrosis, inflammation, and arteriolopathy) in the Tac group were markedly improved by Fx administration. Increases in apoptotic cell death and activation of proapoptotic caspase-3 by Tac were remarkably decreased by Fx treatment. Tac administration increased the activity of XO in kidney tissue and serum, and the levels of 8-OHdG in urine and 8-OHdG and 4-HHE of kidney tissue, but combined treatment with Fx decreased the levels of these parameters.

CONCLUSIONS

Fx is effective in controlling hyperuricemia and in preventing Tac-induced renal injury, via a reduction of oxidative stress. Therefore, a targeted therapy aimed at inhibiting uric acid by Fx may be a useful approach in the management of the progression of nephropathy in renal transplant patients treated with Tac.

Cyclosporine A disposition, hepatic and renal tolerance in Wistar rat

Cyclosporine A, a potent calcineurin inhibitor, has been widely used in organ transplantation and in the treatment of autoimmune diseases. It has, however, been shown to induce serious renal and hepatic side effects. The drug is also used in preclinical studies, but with little published information on the optimal dose and route of administration in rodents. Objectives of this study were to identify efficient and safe doses of cyclosporine A in rodent and to assess its effects on hepatic and renal functions. For this purpose, we tested the effects of different doses and administration routes of cyclosporine A (5, 2.5 and 1 mg/kg) administered during 28 days intraperitoneally, or by gastric feeding on Wistar rats. Our data indicate that rats injected intraperitoneally with 5 mg/kg/2d (every two days) exhibited trough cyclosporine A levels within known therapeutic range in human, but were subject to blood cyclosporine A accumulation, whereas the 5 mg/kg/d gavage resulted in only a small cyclosporine A accumulation over time. In both cases this accumulation was not deleterious to renal and hepatic functions, as shown by transaminase, urea, creatinine and bilirubin measurements.

Calcineurin inhibitors cyclosporine A and tacrolimus induce vascular inflammation and endothelial activation through TLR4 signaling

The introduction of the calcineurin inhibitors (CNIs) cyclosporine and tacrolimus greatly reduced the rate of allograft rejection, although their chronic use is marred by a range of side effects, among them vascular toxicity. In transplant patients, it is proved that innate immunity promotes vascular injury triggered by ischemia-reperfusion damage, atherosclerosis and hypertension. We hypothesized that activation of the innate immunity and inflammation may contribute to CNI toxicity, therefore we investigated whether TLR4 mediates toxic responses of CNIs in the vasculature. Cyclosporine and tacrolimus increased the production of proinflammatory cytokines and endothelial activation markers in cultured murine endothelial and vascular smooth muscle cells as well as in ex vivo cultures of murine aortas. CNI-induced proinflammatory events were prevented by pharmacological inhibition of TLR4. Moreover, CNIs were unable to induce inflammation and endothelial activation in aortas from TLR4^−/− mice. CNI-induced cytokine and adhesion molecules synthesis in endothelial cells occurred even in the absence of calcineurin, although its expression was required for maximal effect through upregulation of TLR4 signaling. CNI-induced TLR4 activity increased O₂⁻/ROS production and NF-κB-regulated synthesis of proinflammatory factors in cultured as well as aortic endothelial and VSMCs. These data provide new insight into the mechanisms associated with CNI vascular inflammation.

The effect of immunosuppressive drug cyclosporine A on myeloid-derived suppressor cells in transplanted mice

OBJECTIVE

Myeloid-derived suppressor cells (MDSCs) play important roles in preventing graft rejection. Immunosuppressive drug cyclosporine A (CsA) is widely used in clinics to treat patients with allografts and autoimmune diseases. However, the effect of CsA on CD11b(+)Gr1(+) MDSCs has not been studied.

SUBJECTS

The subjects of the study include BALB/c skin-grafted C57BL/6 mice and the in vitro MDSCs induction system.

TREATMENT

Skin-grafted mice were treated with CsA (30 mg/kg, i.p.) or control buffer daily. 0.01 μg/ml CsA was added during MDSC induction.

METHODS

Flow cytometry was used to check cell phenotypes and proliferation. Real-time PCR was used for gene expressions. Inducible nitric oxide synthase iNOS-knockout mice were used for the role of iNOS in the immunosuppression of MDSCs.

RESULTS

CsA in MDSC-induction system significantly increased the number of CD11b(+)Gr1(+)MDSCs without detectable effects on the expressions of CD31, CD115 and CD274. However, GM-CSF + CsA-induced MDSCs express higher iNOS than control MDSCs. Blocking iNOS activity by inhibitor or gene deletion significantly reversed the inhibitory effects of GM-CSF + CsA-induced MDSCs on T cell proliferation. Importantly, CsA treatment significantly increased the number and the immunosuppressive ability of CD11b(+)Gr1(+)MDSCs in allogeneic skin-grafted mice.

CONCLUSIONS

CsA promotes MDSC induction and immunosuppressive function, which might be of clinical importance in treating graft rejection and autoimmune diseases.

Cyclosporine A induced histological changes of Cathepsin L and CD2AP expression in renal glomeruli and tubules

BACKGROUND

Cyclosporine A (CsA) is used globally as an immunosuppressant for the treatment of immune-mediated nephrotic syndrome (NS). However, its long-term use causes nephrotoxicity characterized by tubulointerstitial injury and glomerulosclerosis. The present study aimed to investigate the associations between histomorphological findings and immunohistological expression of Cathepsin L (CatL) and CD2-associated protein (CD2AP) in patients with NS mediated with CsA.

METHODS

A total of 18 patients with child-onset NS were divided into two groups after treatment with CsA for 2 years (group A; n = 10) and more than 4 years (group B; n = 8), respectively. Analyses of relationships between tubulointerstitial disorders and expression of CatL and CD2AP proteins were performed using immunohistochemistry of paired renal specimens.

RESULTS

Glomeruli with arteriole hyalinization were significantly increased in both groups depending on dosage periods, although degrees of tubule and interstitial injury did not differ between groups. CD2AP expression was significantly greater in podocytes (P = 0.046) and was significantly less in proximal tubule cells (P = 0.014) in patients of group B compared with those of group A. Moreover, CD2AP expression was significantly increased in lateral tubule cells in both groups (group A, P = 0.02; group B, P = 0.001), and CatL expression in glomeruli and tubule cells did not change with the duration of CsA treatment in either patient group.

CONCLUSIONS

CD2AP expression in renal tubules may histologically associate with tissue hypoxia and reflected recovery from CsA-mediated renal injury in patients, even with mild histological features of tubulointerstitial disorder.

Pharmacokinetic and nephroprotective benefits of using Schisandra chinensis extracts in a cyclosporine A-based immune-suppressive regime

Cyclosporine A (CsA) is a powerful immunosuppressive drug. However, nephrotoxicity resulting from its long-term usage has hampered its prolonged therapeutic usage. Schisandra chinensis extracts (SCE) have previously been used in traditional Chinese medicine and more recently coadministered with Western medicine for the treatment of CsA-induced side effects in the People’s Republic of China. This study aimed to investigate the possible effects of SCE on the pharmacokinetics of CsA in rats and elucidate the potential mechanisms by which it hinders the development of CsA-induced nephrotoxicity. A liquid chromatography/tandem mass spectrometry method was developed and validated for determining the effect of SCE on the pharmacokinetics of CsA. Male Sprague Dawley rats, which were administered with CsA (25 mg/kg/d) alone or in combination with SCE (54 mg/kg/d and 108 mg/kg/d) for 28 days, were used to evaluate the nephroprotective effects of SCE. Our study showed that SCE increased the mean blood concentration of CsA. Furthermore, we found that the concomitant administration of SCE alongside CsA prevented the disruption of catalase activity and reduction in creatinine, urea, renal malondialdehyde, and glutathione peroxidase levels that would have otherwise occurred in the absence of SCE administration. SCE treatment markedly suppressed the expression of 4-hydroxynonenal, Bcl-2-associated X protein, cleaved caspase 3, and autophagy-related protein LC3 A/B. On the other hand, the expression of heme oxygenase-1, nuclear factor erythroid 2-related factor 2 (Nrf2), and P-glycoprotein was enhanced by the very same addition of SCE. SCE was also able to increase the systemic exposure of CsA in rats. The renoprotective effects of SCE were thought to be mediated by its antiapoptotic and antioxidant abilities, which caused the attenuation of CsA-induced autophagic cell death. All in all, these findings suggest the prospective use of SCE as an effective adjunct in a CsA-based immunosuppressive regimen.

The role for microRNAs in drug toxicity and in safety assessment

INTRODUCTION

Adverse drug reactions present significant challenges that impact pharmaceutical development and are major burdens to public health services worldwide. In response to this need, the field of toxicology is rapidly expanding to identify key pathways involved in drug toxicity.

AREAS COVERED

MicroRNAs (miRNAs) are a class of small evolutionary conserved endogenous non-coding RNAs that regulate the translation of protein-coding genes. A wide range of toxicants alter miRNA levels in target organs and these altered miRNAs can also be detected in easily accessible biological fluids. This, combined with an early miRNA response to toxic insults and miRNA stability, substantiates the potential for these small molecules to be useful biomarkers for drug safety assessment.

EXPERT OPINION

miRNAs are early indicators and useful tools to detect drug-induced toxicity. Incorporation of miRNA profiling into the drug safety testing process will complement currently used techniques and may substantially enhance drug safety. With the increasing interests in translational research, the field of miRNA biomarker research will continue to expand and become an important part of the investigation of human drug toxicity.