CsA-induced Oxidative Stress Research Articles

Cyclosporine A Downregulates Selenoprotein P Expression via a Signal Transducer and Activator of Transcription 3–Forkhead Box Protein O1 Pathway in Hepatocytes In Vitro

Cyclosporine A (CsA) is an immunosuppressant applied worldwide for preventing graft rejection and autoimmune diseases. However, CsA elevates oxidative stress, which can lead to liver injuries. The present study aimed to clarify the mechanisms underlying the CsA-mediated oxidative stress. Among the redox proteins, CsA concentration-dependently downregulated Selenop-encoding selenoprotein P, a major circulating antioxidant protein reducing reactive oxygen species, in hepatocytes cell lines and primary hepatocytes. The luciferase assay identified the CsA-responsive element in the SELENOP promoter containing a putative binding site for forkhead box protein O (FoxO) 1. The CsA-mediated suppression on the SELENOP promoter was independent of the nuclear factor of activated T-cell, a classic target repressed by CsA. A chromatin immunoprecipitation assay showed that CsA suppressed the FoxO1 binding to the SELENOP promoter. Foxo1 knockdown significantly downregulated Selenop expression in H4IIEC3 cells. Furthermore, CsA downregulated FoxO1 by inactivating its upstream signal transducer and activator of transcription 3 (STAT3). Knockdown of Stat3 downregulated Foxo1 and Selenop expression in hepatocytes. These findings revealed a novel mechanism underlying CsA-induced oxidative stress by downregulating the STAT3-FoxO1-Selenop pathway in hepatocytes. SIGNIFICANCE STATEMENT: This study shows that Cyclosporine A (CsA) downregulates Selenop, an antioxidant protein, by suppressing the signal transducer and activator of transcription 3-forkhead box protein O1 pathway in hepatocytes, possibly one of the causations of CsA-induced oxidative stress in hepatocytes. The present study sheds light on the previously unrecognized CsA-redox axis.

Cyclosporine A Downregulates Selenoprotein P Expression via a Signal Transducer and Activator of Transcription 3-Forkhead Box Protein O1 Pathway in Hepatocytes In Vitro.

Cyclosporine A (CsA) is an immunosuppressant applied worldwide for preventing graft rejection and autoimmune diseases. However, CsA elevates oxidative stress, which can lead to liver injuries. The present study aimed to clarify the mechanisms underlying the CsA-mediated oxidative stress. Among the redox proteins, CsA concentration-dependently downregulated Selenop-encoding selenoprotein P, a major circulating antioxidant protein reducing reactive oxygen species, in hepatocytes cell lines and primary hepatocytes. The luciferase assay identified the CsA-responsive element in the SELENOP promoter containing a putative binding site for forkhead box protein O (FoxO) 1. The CsA-mediated suppression on the SELENOP promoter was independent of the nuclear factor of activated T-cell, a classic target repressed by CsA. A chromatin immunoprecipitation assay showed that CsA suppressed the FoxO1 binding to the SELENOP promoter. Foxo1 knockdown significantly downregulated Selenop expression in H4IIEC3 cells. Furthermore, CsA downregulated FoxO1 by inactivating its upstream signal transducer and activator of transcription 3 (STAT3). Knockdown of Stat3 downregulated Foxo1 and Selenop expression in hepatocytes. These findings revealed a novel mechanism underlying CsA-induced oxidative stress by downregulating the STAT3-FoxO1-Selenop pathway in hepatocytes. SIGNIFICANCE STATEMENT: This study shows that Cyclosporine A (CsA) downregulates Selenop, an antioxidant protein, by suppressing the signal transducer and activator of transcription 3-forkhead box protein O1 pathway in hepatocytes, possibly one of the causations of CsA-induced oxidative stress in hepatocytes. The present study sheds light on the previously unrecognized CsA-redox axis.

Protective effect of hydroxysafflor yellow A on cyclosporin A-induced renal oxidative stress in vitro and in vivo.

ABSTRACTPurpose:To explore the mechanism and investigate the protective effect of hydroxysafflor yellow A (HSYA) on renal oxidative stress, which cyclosporine A (CsA) induces.Methods:HK-2 cells were treated with CsA to get CsA-induced oxidative stress. The effects on oxidative stress and apoptosis of HK-2 cells were detected. The contents of SOD, MDA, GSH-Px, ROS, and CAT in serum were measured, and the expression of apoptosis-related proteins was detected by western blot. Then, established the renal oxidative stress injury rats to verify the efficacy of HSYA.Results:HSYA could reduce the ROS and MDA contents induced by CsA. Compared with the CsA group, the activities of SOD, CAT, and GSH-Px increased significantly when treated with HSYA. HSYA could inhibit CsA-induced apoptosis in HK-2 cells, and promote the protein of Bcl-2 and inhibit the expression of Bax. Animal experiments showed that HSYA could reduce CsA-induced renal cell injury by reducing glomerular cell vacuoles and inflammatory factors in tissues. It also decreased serum creatinine (Crea) and blood urea nitrogen, increased Crea clearance significantly.Conclusions:HSYA could significantly improve the antioxidant capacity of the kidney cells and inhibit cell apoptosis, thereby effectively ameliorating CsA-induced oxidative stress in vitro and in vivo.

Antioxidants protect against gingival overgrowth induced by cyclosporine A.

We investigated the importance of reactive oxygen species (ROS) on developing gingival overgrowth (GO) and then introduced the antioxidant strategy to prevent, or even reduce GO. Gingival overgrowth is a common side effect of the patients receiving cyclosporine A (CsA), an immune suppressant. Although it has been broadly investigated, the exact pathogenesis of the induced GO is still uncertain. We cultured human primary gingival fibroblasts and used animal model of GO to investigate the ameliorative effects of antioxidants on CsA-induced GO. To examine the CsA-induced oxidative stress, associated genes and protein expression, and the overgrown gingiva of rats by using immunocytochemistry, confocal laser scanning microscopy, real-time PCR, ELISA, gelatin zymography, gingival morphological, and immunohistochemical analysis. We found for the first time that ROS was responsible for the CsA-induced oxidative stress and TGF-β1 expression in human primary gingival fibroblasts, as well as the GO of rats. The antioxidants (oxidative scavenger of vitamin E and an antioxidative enzyme inducer of hemin) ameliorated CsA-induced pathological and morphological alterations of GO without affected the CsA-suppressed il-2 expression in rats. CsA-induced oxidative stress, HO-1, TGF-β1, and type II EMT were also rescued by antioxidants treatment. We concluded that CsA repetitively stimulating the production of ROS is the cause of CsA-GO which is ameliorated by treating antioxidants, including vitamin E and sulforaphane. Furthermore, the immunosuppressive effect of CsA is not interfered by antioxidant treatments in rats. This finding may thus help the clinician devise better prevention strategies in patients susceptible to GO.

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.

The Effects of Valsartan on Renal Klotho Expression and Oxidative Stress in Alleviation of Cyclosporine Nephrotoxicity.

Nephrotoxicity side effect of the immunosuppressive drug, cyclosporine A (CsA), can be a major issue in transplantation medicine. Cyclosporine A-induced nephrotoxicity is multifactorial but oxidative stress has a critical role in this process. It has been demonstrated that Valsartan (Val) as an angiotensin receptor blocker has renoprotective effects, but the molecular mechanisms responsible for the renal protection, independent from its blood pressure lowering effect, have not yet been fully understood. The present study is aim at evaluating the Val effect in alleviation of CsA nephrotoxicity by probable increase in renal Klotho expression and/or reducing oxidative stress. Thirty-two Sprague-Dawley rats were divided into 4 groups based on the administration of CsA and/or Val: group A (control, 1 mL/kg per day of olive oil as vehicle), group B (CsA, 30 mg/kg per day), group C (CsA + Val, 30 + 30 mg/kg per day), and group D (Val, 30 mg/kg per day). Real-time polymerase chain reaction and Western blotting were used to evaluate Renal Klotho expression. Serum Klotho level was measured by enzyme-linked immunosorbent assay. 8-Hydroxy-deoxy guanosine and malondialdehyde levels as markers of oxidative stress were measured by enzyme-linked immunosorbent assay and spectrophotometrically, respectively. Cyclosporine A treatment reduced renal expression and serum levels of Klotho, improved malondialdehyde and 8-hydroxy-deoxy guanosine levels, and also deteriorated renal function. Valsartan prevented CsA-induced oxidative stress as well as Klotho downregulation and could alleviate CsA-induced renal histological changes and function. Administration of Val might lead to amelioration of CsA nephrotoxicity by probably diminishing CsA-induced renal Klotho downregulation and oxidative stress.

Regular endurance exercise prevents cyclosporine A-induced oxidative stress in mouse skeletal muscles

Summary Introduction Cyclosporine A (CsA) is a widely used immunosuppressive agent to treat allograft rejection and autoimmune diseases. This treatment could also contribute to several adverse effects, including decreased muscle functions and multiorgan failures, due to increased oxidative stress and/or decreased antioxidant capacity. The aim of this study was to investigate the effect of 8-week endurance exercise on activities of antioxidant enzymes and oxidative stress in quadriceps muscle of CsA-treated mice. Summary of facts BALB/c female mice were randomly assigned to the following four groups: 0-Ex (no CsA and no exercise), 0+Ex (no CsA and exercise), 20-Ex (CsA 20 mg/kg per day and no exercise), and 20+Ex (CsA 20 mg/kg per day and exercise) with eight in each group. The exercise groups ran on a treadmill at approximately 75% VO 2max for 45 minutes, 3 days per week. CsA or exercise alone did not change superoxide dismutase (SOD) and glutathione peroxidase (GPX) activities. The combination of CsA administration and endurance exercise significantly increased quadriceps SOD and GPX activities. In the absence of exercise, CsA resulted in significantly higher protein carbonyl (PC) concentrations. On the other hand, endurance exercise significantly reduced muscle PC concentration in the CsA-treated group. Conclusion This study suggested that regular endurance exercise could improve muscle antioxidant capacity and, therefore, protect against CsA-induced oxidative stress.

Aqueous extract of Terminalia arjuna prevents cyclosporine-induced renal disorders

Cyclosporine (CsA), a powerful immunosuppressant, had a significant impact on transplantation medicine, and exposure to this chemical is known to induce oxidative stress and causes renal injury by the formation of free radicals. Acute and chronic renal damage are very common pathophysiologic disturbances caused by CsA. The present study has been conducted to evaluate the protective role of the aqueous extract of the bark of Terminalia arjuna (TA), an important Indian medicinal plant widely used in the preparation of ayurvedic formulations, on CsA-induced oxidative stress and resultant dysfunction in the rat kidney. Animals were treated with the aqueous extract of TA (100 mg/kg body weight (b.wt)) and then treated with CsA (25 mg/kg b.wt) in olive oil for 14 days. The level of urea, uric acid, and creatinine was determined from serum sample. The enzymes, namely, alkaline phosphatase (ALP), acid phosphatase (ACP), aspartate transaminase (AST), and alanine transaminase (ALT), and enzymic indices of membrane integrity such as Na+K+ATPase, Ca2+ATPase, and Mg2+ATPases were estimated in the tissue of all study groups. Antioxidant status in kidney tissues was estimated by determining the activities of the antioxidative enzymes, superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), and glutathione transferase (GST) and the levels of reduced glutathione, vitamin E, and vitamin C. In addition, the kidney phospholipids, cholesterol, triglycerides, and free fatty acids were determined in the tissue. Results showed that CsA caused a marked increase in the levels of urea, uric acid, and creatinine in serum and decreases the levels of ALP, ACP, AST, ALT, Na+K+ATPase, Ca2+ATPase, Mg2+ATPases, SOD, CAT, glutathione reductase, GST, GPx, vitamin E, and vitamin C whereas cholesterol, triglycerides, free fatty acid, and phospholipid levels were found to be increased in the kidney tissue homogenates of CsA-treated rats. Aqueous extract of TA successfully prevented the alterations of these effects in the experimental animals. Data also showed that the extract possessed strong free radical scavenging activity comparable to that of vitamin C. Our study demonstrated that the aqueous extract of the bark of TA could protect the kidney tissues against CsA-induced oxidative stress probably by increasing antioxidative defense activities.

Statin Upregulates the Expression of Klotho, an Anti-Aging Gene, in Experimental Cyclosporine Nephropathy

Background: We recently reported that long-term cyclosporine (CsA)-induced oxidative stress is associated with decreased expression of klotho, an anti-aging gene. This study evaluated whether the antioxidant effect of statin might upregulate klotho expression in CsA-induced renal injury. Methods: Two separate experiments were performed. First, the dose-dependent effect of statin on klotho expression was evaluated in normal mouse kidneys. Second, the effect of statin on klotho expression was evaluated in experimental chronic CsA nephropathy in mice. We performed immunohistochemistry and immunoblotting for klotho, Forkhead box O transcription factors [FoxOs; phosphorylated FoxO1 (p-FoxO1) and FoxO3a (p-FoxO3a)] and their target molecules, manganese superoxide dismutase (MnSOD), Bim and hemeoxygenase-1. Results: Statin treatment upregulated klotho expression in a dose-dependent manner in the normal mouse kidney and alleviated the decrease in klotho expression in kidneys exhibiting CsA nephropathy. CsA administration increased p-FoxO1 expression and decreased p-FoxO3a expression, whereas concurrent statin treatment reversed these changes, increased the expression of the antioxidant enzymes MnSOD and hemeoxygenase-1 and decreased the expression of the pro-apoptotic protein Bim. Conclusion: Statin-mediated upregulation of klotho expression and differential regulation of FoxO expression promote resistance to CsA-induced oxidative stress.

Chronic Cyclosporine Nephropathy Is Characterized by Excessive Autophagosome Formation and Decreased Autophagic Clearance

The study was performed to investigate the influence of cyclosporine A (CsA)-induced renal injury on autophagy in an experimental model of chronic CsA nephropathy. Three dosages of CsA (7.5, 15, and 30 mg/kg/day) were administered to mice for 4 weeks. The formation of autophagosomes was measured with microtubule-associated protein 1 light chain 3 phospholipid-conjugated form (LC3-II) and beclin-1, and the ability of autophagic clearance was examined with sequestosome-1 (p62). Autophagic vacuoles were visualized and counted using electron microscopy. Double immunolabeling of LC3-II and active caspase-3 was performed to evaluate the association between autophagy and apoptosis. Oxidative stress was evaluated by measuring urinary 8-hydroxy-2'-deoxyguanosine excretion, demonstrating oxidative DNA damage. Antioxidative drugs, pravastatin and N-acetylcysteine, were used to evaluate the role of CsA-induced oxidative stress on autophagy. CsA treatment increased the expressions of LC3-II and beclin-1 in the kidney in a dose-dependent manner. The number of p62-positive cells was also significantly increased in a CsA dose-dependent manner. Electron microscopy revealed excessive autophagic vacuoles in the CsA group compared with the vehicle group. Expression of active caspase-3 was increased in a CsA dose-dependent manner and was colocalized with LC3-II in the injured area of CsA-treated kidneys. Concurrent pravastatin or N-acetylcysteine treatment reduced urinary excretion of 8-hydroxy-2'-deoxyguanosine and subsequently decreased LC3-II expression and the number of p62-positive cells compared with the CsA group. Chronic CsA nephropathy is a state of excessive autophagic vacuoles and decreased autophagic clearance. Oxidative stress may play an importation role in the induction of autophagy.

Role of Oxidative Stress in the Colonic Complications of Murine Syngeneic Graft-versus-host Disease

Syngeneic graft-versus-host disease (SGVHD) develops in mice following lethal irradiation, reconstitution with syngeneic bone marrow (BM) and treatment with a short course of the immunosuppressive agent cyclosporine A (CsA). The development of SGVHD is a complex process resulting from the cooperative interaction of multiple effector cell populations and inflammatory mediators contributing to the pathogenesis of this inducible disease. Using gene ex- pression analysis, flow cytometric analysis and immunohistochemistry, time course studies revealed increased reactive oxygen and nitrogen species in the tissues of CsA-treated animals compared to bone marrow transplantation (BMT) con- trols during the induction of SGVHD (d0-21 post-BMT). Studies were undertaken to determine the effect of CsA-induced oxidative stress on the induction of SGVHD. In vivo treatment with the superoxide dismutase mimetic, manganese (III) meso-tetrakis (4-benzoic acid) porphyrin (MnTBAP), during (d0-21 post BMT), or after CsA therapy (>d21 post-BMT), caused a reduction in the development of clinical symptoms of SGVHD (weight loss, diarrhea). Interestingly, treatment with MnTBAP resulted in a significant reduction in the deposition of peroxynitrite in the colons of CsA-MnTBAP-treated versus control CsA-treated SGVHD animals. These studies suggest a role for oxidative stress in the development of mur- ine SGVHD.

English

Nephrotoxicity is a major problem of Cyclosporine A (CsA) treatment, despite its beneficial role in organ transplantation and in a variety of immunologic disorders. This study was undertaken to investigate the potential renoprotective role of telmisartan in amelioration of chronic CsA induced nephrotoxicity. The rats were randomized into 4 equal groups. Group 1 received normal saline (control), group 2 received Cremophor EL and ethanol (CsA vehicle), group 3 received CsA 25 mg/kg/day s.c and group 4 received telmisartan 3 mg/kg/day orally in addition to CsA. The rats were pair fed with a standard chow diet throughout the experiment period (8 weeks). CsA nephrotoxicity was assessed in terms of increased S.Cr (from 0.52± 0.16 to 1.29 ± 0.20 mg/ml), blood urea (from 24.69 ± 1.89 to 75.88± 2.33 mg/ml) and serum K (from 3.43 ± 0.18 to 5.23 ± 0.43 meq/l). CsA also caused significant increase (p<0.01) in MDA (from 0.74 ± 0.13 to 2.96 ± 0.43 nmol/mg protein) and significant decrease (p<0.01) in GSH and catalase in renal tissue. Telmisartan failed to restore the altered renal functions. On the other hand, it causes a significant improvement in the histological changes including the tubulointerstitial fibrosis and arteriolopathy (p<0.01). It also caused significant reduction (p<0.01) in CsA-induced oxidative stress. These findings suggested that telmisartan has a promising renoprotective effect against chronic CsA induced nephrotoxicity. Key words: Cyclosporine A, nephrotoxicity, oxidative stress, telmisartan.

Attenuation of cyclosporine A-induced testicular and spermatozoal damages associated with oxidative stress by ellagic acid

This study was conducted to investigate the possible protective effect of ellagic acid (EA) on cyclosporine A (CsA)-induced testicular and spermatozoal damages associated with oxidative stress in male rats. Forty adult male Sprague–Dawley rats were divided into 4 groups of 10 animals each. Control group was used as placebo. Cyclosporine group received CsA at the dose of 15 mg/kg/day. Ellagic acid group was treated with EA (10 mg/kg/day). Cyclosporine plus ellagic acid group received CsA + EA. Reproductive organs were weighed and epididymal sperm characteristics and histopathological structure of testes were examined along with malondialdehyde (MDA) and glutathione (GSH) levels, glutathione-peroxidase (GSH-Px) and catalase (CAT) activities in testicular tissue. CsA significantly decreased the weights of testes and ventral prostate, epididymal sperm concentration, motility, testicular tissue glutathione (GSH), glutathione-peroxidase (GSH-Px) and catalase (CAT), diameters of seminiferous tubules and germinal cell layer thickness, and it significantly increased malondialdehyde (MDA) level and abnormal sperm rates along with degeneration, necrosis, immature germ cells, congestion and atrophy in testicular tissue. However, the CsA plus EA treatment attenuated all the CsA-induced negative changes observed in the testicular tissue, sperm and oxidant/antioxidant parameters. In conclusion, CsA-induced oxidative stress leads to the structural and functional damages in the testicular tissue and sperm quality of rats, and also EA has a protective effect on these damages.

Cyclosporin A Up-Regulates and Activates Protein Kinase C-ζ in EBV-Infected and EBV-Transformed Human B-Cells

Protein Kinase C (PKC) is a family of enzymes that plays a key role in cell signaling pathways leading to cellular activation and proliferation. Conventional PKC (cPKC) is dependent on calcium for activation. We have proposed that cyclosporin A (CsA), despite being a calcineurin inhibitor, will activate PKC in B cells, thus promoting Epstein-Barr virus (EBV)-induced transformation. Here we show that CsA promoted atypical PKC isoform PKC-zeta in B cells. Western-blot was used to assay PKC-zeta protein level in EBV-B cells. Confocal microscopy was used to assay PKC-zeta translocation from cytosol to cell membrane, a known process of PKC activation. CsA (500 ng/mL) time dependently increased PKC-zeta from control of 7055 units to 7145, 10,805, 10,914, and 12,705 units, respectively, after 15 min, 1 h, 12 h, and 24 h of incubation in EBV-transformed human B-cell line (LCL). CsA increased PKC-zeta expression was inhibited 50% by Vit.E (40 microM) indicating that this effect may be due to oxidative stress induced by CsA. Indeed, after oxidant H(2)O(2) (0.1 mM) treatment, PKC-zeta protein level in LCL cells increased 124%, 257%, 349%, and 359% after 15 min, 1 h, 12 h, and 24 h of culture compared with control. Addition of Vit.E (40 microM) in H(2)O(2) (0.1 mM) treatment and then with Vit.E in the culture decreased PKC-zeta level in LCL cells 26%, 20%, 41%, and 60% after 15 min, 1 h, 12 h, and 24 h of culture. In confocal microscopy in Jurkat T cell line, phorbol 12-myristate 13-acetate (PMA) activated cPKC isoform PKCalpha after 30 min treatment and activated PKC-zeta after 60 min treatment. CsA inhibited PMA activation of PKC-alpha, but not PKC-zeta. CsA alone did not activate PKC-alpha or PKC-zeta in Jurkat T cells. In LCL and in EBV-infected human B-cells, PMA stimulated PKC-alpha activation after 30 min treatment and stimulated PKC-zeta activation after 60 min treatment. CsA inhibited PMA activation of PKC-alpha, but not PKC-zeta. In addition, CsA activated PKC-zeta in the EBV-transformed and EBV-infected human B cells. These experiments show that CsA-induced oxidative stress caused PKC-zeta up-regulation in LCL cells, and show the differential effect of CsA in the PKC signaling pathways in T cells versus B cells. CsA-induced PKC-zeta activation may be an important signaling step in EBV-induced post-transplant lymphoproliferative disorders.

Cyclosporin A-Induced Lipid and Protein Oxidation in Human B-Cells and in Epstein-Barr Virus-Infected B-Cells is Prevented by Antioxidants

The incidence of post-transplant lymphoproliferative disorder (PTLD) has increased since cyclosporin A (CsA) became the mainstay of transplant immunosuppression. We have previously shown that, in addition to its potent immunosuppressive property, CsA-induced oxidative stress plays an important role in Epstein-Barr virus (EBV)-related PTLD. Using lipid hydroperoxide and malondialdehyde as markers of lipid oxidation, and protein carbonyls as markers of protein oxidation, we further investigated the in vitro effect of CsA on human B cells and EBV-infected human B cells. We found that CsA at 500 ng/ml, a relatively safe and effective blood concentration in organ transplant recipients, induced the highest lipid hydroperoxide and malondialdehyde after 10 min of treatment in time- and concentration-related kinetic studies. We also found that treatment with CsA at 500 ng/ml for 10 min increased the EBV-infected B cell protein carbonyl formation as assayed by immunoblot method. CsA-induced lipid and protein oxidation could be inhibited by vitamin E, N-acetyl cysteine, and pyrollidine dithiocarbamate. CsA significantly promoted the EBV-B cell transformation as assayed by colony counting, cell counting, and 3H-thymidine incorporation. Our recent study provides further evidence to support the hypothesis that CsA exerts direct oxidative stress in EBV-infected as well as non-EBV-infected human B cells. A greater understanding of these cellular and molecular mechanisms may benefit the clinical practice and prevention of PTLD.

Oxidative Stress in Cyclosporine-Induced Hypertension: Evidence of Beneficial Effects or Tolerance Development With Nitrate Therapy

The aim of this study was to evaluate the effect of cyclosporine (CsA) on oxidative stress as well as the use of a nitric oxide (NO) donor, the organic nitrate isosorbide-5-mononitrate (Is-5-Mn), to prevent or reverse CsA-induced toxicity, namely on the vascular NO-cGMP pathway or on oxidative equilibrium. The following rat groups (n = 8) were tested: (1) a control group; (2) the CsA group (5 mg/kg/d for 7 weeks); (3) the Is-5-Mn group (150 mg/kg/d, twice a day for 7 weeks); (4) the preventive group (Is-5-Mn + CsA) treated for 2 weeks with Is-5-Mn only, and thereafter with both drugs for 7 weeks; (5) the curative group (CsA + Is-5-Mn) beginning 7 weeks after CsA, and following thereafter with both drugs for 5 weeks. The following parameters were evaluated: aortic cNOS activity and cGMP content; plasma levels of lipid peroxidation (malondialdehyde [MDA] levels); antioxidant capacity (glutathione peroxidase [GPx] and superoxide dismutase [SOD] activities, total antioxidant status, and vitamins A, C, and E); and peroxynitrite formation (3-nitrotyrosine [3-NT] content). Is-5-Mn + CsA therapy showed, when compared with the CsA group, total prevention of CsA-induced NO and cGMP attenuation, and no relevant influence on antioxidant indices, as well as on MDA and 3-NT levels. However, when compared with this CsA group, the curative group (CsA + Is-5-Mn) showed NO-cGMP values only partially reversed, and an enhancement in lipid peroxidation (5.6 ± 1.4 vs 12.78 ± 3.63 μmol/L; P < .05) and in peroxynitrite formation (16.7% incidence of positives vs 83.3% incidence of positives). Our data suggested that nitrate therapy may provide a valid choice to prevent CsA-induced NO-cGMP decrease, without a negative influence on the oxidative equilibrium. However, when the local environment is adverse, as occurs after CsA therapy, Is-5-Mn seemed to enhance the CsA-induced oxidative stress, promoting even worse deleterious effects, probably through the generation of the cytotoxic ROS peroxynitrite.

In vivo effect of the natural antioxidant hydroxytyrosol on cyclosporine nephrotoxicity in rats

Cyclosporine A (CsA) is the first-line immunosuppressant used in transplant patients and in auto- immune diseases. Nephrotoxicity is the major limitation of CsA use. Although the mechanisms of nephrotoxicity have not been completely defined, some evidence suggests that reactive oxygen species (ROS) play a causal role. The present study was designed to investigate in vivo effects of hydroxytyrosol (DOPET), a natural olive oil antioxidant, on oxidative stress, renal histology and haemodynamic alterations induced in rats by CsA treatment. Adult Sprague-Dawley rats were treated i.p. with CsA (15 mg/kg) alone or in combination with DOPET (20 mg/kg) for 3 weeks. At the end of the treatment, superoxide concentration within the cells of the abdominal aorta and renal artery was quantified from the oxidation of dihydroethidium (DHE) using fluorescence microscopic imaging analysis. In kidney tissues, lipid peroxidation was measured by thiobarbituric acid-reacting substances (TBARS) assay, glutathione level was assessed enzymatically and the expression of haem oxygenase-1 (HO-1) gene was evaluated by semiquantitative RT-PCR. Renal morphology was studied by classical histological techniques, while the glomerular filtration rate (GFR) was estimated by inulin clearance. Systemic blood pressure was monitored by the tail method and through the catheterization of the carotid artery. CsA administration increased superoxide concentration both in the aorta and in the renal artery, while DOPET completely prevented this effect. Higher levels of TBARS, a significant decrease in GSH and an upregulation of HO-1 mRNA were observed in the kidneys of CsA-treated rats. DOPET treatment reversed quantitatively these effects. However, CsA-dependent changes in renal histology were only partially reversed by DOPET. Finally, CsA induced a severe reduction in GFR and a significant increase in both systolic and diastolic blood pressure; the DOPET treatment had no significant effect on these haemodynamic alterations. The reported data indicate that effective DOPET protection from CsA-induced oxidative stress is associated with a mild effect on histological damages and does not affect the altered glomerular function and the hypertension, thus indicating that kidney injury by CsA is only in part dependent on oxidative stress.

Lycopene protects against cyclosporine A-induced testicular toxicity in rats

Cyclosporine A (CsA)-induced direct failures in hypothalamic–pituitary–gonadal axis and Sertoli cell phagocytic function have been considered for testicular toxicity so far. It has clearly been reported that oxidative stress leads to damage in sperm functions and structure of the testis. Therefore, this study was conducted to demonstrate whether CsA causes testicular and spermatozoal toxicity associated with the oxidative stress, and to investigate the possible protective effect of lycopene against CsA-induced damages in all reproductive organs and sperm characteristics in male rats. While the daily administration of CsA at the dose 15 mg/kg for 21 days significantly decreased the seminal vesicles weight, epididymal sperm concentration, motility, testicular tissue glutathione (GSH), glutathione peroxidase (GSH-Px) and catalase (CAT), diameter of seminiferous tubules and germinal cell thickness, it increased malondialdehyde (MDA) level and abnormal sperm rates along with degeneration, necrosis, desquamative germ cells in testicular tissue. However, the CsA along with simultaneous administration of lycopene at the dose of 10 mg/kg markedly ameliorated the CsA-induced all the negative changes observed in the testicular tissue, sperm parameters and oxidant/antioxidant balance. In conclusion, CsA-induced oxidative stress leads to the structural and functional damages in the testicular tissue and sperm quality of rats and, lycopene has a potential protective effect on these damages.

Spirulina attenuates cyclosporine‐induced nephrotoxicity in rats

Cyclosporine (CsA) causes a dose-related decrease in renal function in experimental animals and humans. The generation of reactive oxygen species (ROS) has been implicated in CsA-induced nephrotoxicity. It was previously shown that Spirulina, a blue-green algae, with antioxidant properties effectively attenuated the doxorubicin-induced cardiotoxicity in mice and cisplatin-induced nephrotoxicity in rat. The present study investigated the nephroprotective role of Spirulina against CsA-induced nephrotoxicity in rats. Spirulina (500 mg kg(-1) b.w.) was administered orally for 3 days before and 14 days concurrently with CsA (50 mg kg-1 b.w.). Rats treated with CsA showed nephrotoxicity as evidenced from a significant elevation in plasma urea, creatinine, urinary N-acetyl-beta-D-glucosaminidase (beta-NAG) and a decrease in creatinine and lithium clearance. Pretreatment with Spirulina protected the rats from CsA-induced nephrotoxicity. The CsA-induced rise in plasma urea and creatinine and the decrease in creatinine and lithium clearance were attenuated by Spirulina. There was a significant increase in plasma and kidney tissue MDA with CsA. Spirulina prevented the rise in plasma and kidney tissue MDA. Histopathology of the kidney from CsA-treated rats showed severe isometric vacuolization and widening of the interstitium. However, pretreatment with Spirulina prevented such changes, and the kidney morphology was comparable to that of the control. Spirulina treatment did not alter the blood CsA levels. These results suggest that Spirulina has a protective effect against nephrotoxicity induced by CsA. This study further supports the crucial role of the antioxidant nature of Spirulina in protecting against CsA-induced oxidative stress.

TAURINE ATTENUATES HYPERTENSION AND RENAL DYSFUNCTION INDUCED BY CYCLOSPORINE A IN RATS

Cyclosporine A (CsA) is the first-line immunosuppressant used for the management of solid organ transplantation and autoimmune diseases. Nephrotoxicity is the major limitation of CsA use. Recent evidence suggests that reactive oxygen species (ROS) play an important role in mediating CsA-induced hypertension and nephrotoxicity. Taurine, the major intracellular free beta-amino acid, is known to be an endogenous anti-oxidant and membrane-stabilizing agent. The present study was designed to investigate the effects of taurine on CsA-induced oxidative stress, hypertension and renal dysfunction. 2. Animals were assigned into four groups of seven rats each as follows: (i) control group, receiving vehicle (olive oil; 1 mL/kg, s.c.); (ii) CsA group, given CsA (25 mg/kg per day, s.c.) for 21 days; (iii) taurine group, supplemented with taurine (1% in the drinking water); and (iv) taurine + CsA group, treated with taurine 3 days before and concurrently during CsA injections for 21 days. 3. Cyclosporine A administration elevated blood pressure, reduced serum nitric oxide (NO) levels and deteriorated renal function, as assessed by increased serum creatinine levels and proteinuria and reduced urine flow rate and creatinine clearance compared with vehicle-treated rats. Cyclosporine A induced oxidative stress, as indicated by increased renal tissue concentrations of thiobarbituric acid-reactive substances and reduced concentrations of renal glutathione, glutathione peroxidase and superoxide dismutase. Conversely, no change was noted in renal catalase activity. Moreover, the kidneys of CsA-treated rats showed interstitial inflammation and renal tubular atrophy. 4. Taurine markedly reduced elevated blood pressure, attenuated renal dysfunction and the reduction in serum NO levels and counteracted the deleterious effects of CsA on oxidative stress markers. Furthermore, taurine ameliorated CsA-induced morphological changes. 5. These data clearly indicate the protective potential of taurine against CsA-induced hypertension and nephrotoxicity and suggest a significant contribution of its anti-oxidant property to this beneficial effect.