CsA Administration Research Articles

Effect of Bicarbonate Administration on Cyclosporine-Induced Nephrotoxicity in Rats

Cyclosporine (CsA) is known to cause metabolic and distal tubular acidosis. There is some evidence that CsA reduces net HCO(3)(-) absorption. The aim of this study was to elucidate whether bicarbonate administration prevented CsA-induced functional or structural nephrotoxicity. Seven days after uninephrectomy, 20 rats were divided into 4 groups. NaHCO(3) (0.28 mol/L) was added in drinking water for 7 days, whereas control rats received regular tap water. The bicarbonate pretreated rats were administered either CsA (50 mg/kg intraperitoneally) or vehicle daily for a week. At the end of the procedure, animals were placed in metabolic cages for 24 hours after which we measured creatinine clearance (Ccr), urinary total proteins, pH, and N-acetyl-beta-D-glucosaminidase (NAG) activity. The kidney was fixed in formaldehyde. Ccr was significantly affected by the administration of CsA. The effects of CsA on serum pH and HCO(3)(-) concentration were prevented by pretreatment with NaHCO(3). However, it did not affect the CsA-induced increased urinary NAG activity or decreased Ccr. There was no protection of CsA-induced changes in renal tissues by NaHCO(3). Overall NaHCO(3) administration did not prevent CsA-induced changes in Ccr and NAG activity. These data suggested involvement of factors other than acid-base status in CsA-induced nephrotoxicity. However, correction of acidosis should still be considered for patients receiving CsA because acidosis exacerbates tissue damage.

Suppression of Acute and Chronic Cardiac Allograft Rejection in Mice by Inhibition of Chemokine Receptor 5 in Combination with Cyclosporine A

Inhibition of chemokine receptor 5 (CCR5), a chemokine receptor expressed on activated T cells, is an effective antiviral therapy in patients with HIV infection, but its efficacy in modulating inflammation and immunity is only just beginning to be investigated. In this study we examined the inhibition of CCR5 in combination with the treatment with cyclosporine A in acute and chronic rejection in cardiac transplantation. Eighty fully MHC-mismatched murine cardiac allograft models were randomized to four groups. Recipients in group A were treated with anti-CCR5 mAb and CsA, mice in group B were given anti-CCR5 mAb alone, animals in group C were administered only CsA, and group D were the control group with PBS. Acute and chronic rejection was investigated on day 7 and day 45 post-transplant, respectively. Allografts treated with anti-CCR5 mAb plus CsA showed significantly prolonged survival (44.73 +/- 0.258 d, P < 0.01) compared with PBS-treated group (11.067 +/- 0.707 d). Treatment with anti-CCR5 mAb plus CsA significantly inhibited the progression of CAV. Our findings demonstrated that anti-CCR5 mAb in combination with CsA can prolong the survival of allograft and alleviate both acute and chronic allograft rejection. Thus, combined administration of anti-CCR5 mAb and CsA may become a new therapeutic approach for the prevention of cardiac graft failure that has not been obviated by conventional immunosuppressive agents.

Management of Living Donor Liver Transplant Patients Using Twice-Daily 4-Hour Intravenous Cyclosporine Therapy

Oral administration of cyclosporine (CsA) is the currently favored route in most liver transplant centers. From October 1998 to January 2008, 86 living donor liver transplantations (LDLTs) were performed in 85 patients (46 adults and 39 children) at our institution. Seventy-three patients received tacrolimus (Tac), and 12 intravenous CsA twice daily at a dose of 3 mg/kg/d as a 4-hour continuous infusion. Thirteen of 73 Tac-based patients were switched to CsA because of side effects. Five were switched to intravenous CsA because they were unable to take the drug orally because of severe Tac-related complications. The remaining eight patients switched to oral CsA. We evaluated patients (11 adults and three children), including 12 with induction therapy and two with conversion therapy within 2 weeks of LDLT. The patients were given a 4-hour intravenous infusion of CsA at an initial dose of 3 mg/kg/d. Stable and adequate blood CsA concentrations were achieved by 4-hour intravenous CsA administration. Among several factors, only graft-to-recipient weight ratio (r = .743, P < .0001) showed significant correlations with initial blood CsA concentration. No adverse effects were observed after intravenous CsA. No patients developed biopsy-proven acute cellular rejection (ACR) during intravenous CsA administration, whereas two patients had histopathologically diagnosed episodes of ACR after conversion from intravenous to oral CsA. Our findings suggest that immediate administration of a 4-hour intravenous infusion of CsA at an initial dose of 3 mg/kg/d is practical and effective for routine clinical use.

Effects of Immunosuppressants on the Progression of Hepatitis C in Hepatitis C Virus-Positive Renal Transplantation and the Usefulness of Interferon Therapy

The purpose of this study was to analyze the effects of immunosuppressants on hepatitis C virus (HCV) replication to establish optimal immunosuppressive therapy in HCV-positive renal transplantation. Cyclosporine (CsA), tacrolimus (Tac), mycophenolate acid (MPA), the active metabolite of mycophenolate mofetil (MMF), and methylprednisolone (MP) were administered to HCV replicon cells alone or in combination with interferon (IFN). HCV RNA was quantitatively determined. Of our 2064 recipients of renal transplantations between 1980 and 2005, 153 were HCV-positive. We analyzed changes in hepatic function and the efficacy of IFN therapy in these patients. Only CsA strongly inhibited the growth of HCV RNA (13.1% at 1.0 microg/mL). MPA enhanced the inhibition of the growth of HCV RNA in the presence of IFN. Tac and MP reduced, rather than enhanced, the efficacy of IFN. Progression to chronic hepatitis occurred in a significantly smaller number of patients in the CsA than the Tac group (6 vs 19; P = .04). Serum alanine aminotransferase (ALT) levels were comparable pretransplantation and posttransplantation in the CsA group (24.8 +/- 20.5 vs 28.9 +/- 28.3 IU/L, respectively, while a significant elevation was noted in the Tac group (22.2 +/- 21.5 vs 32.6 +/- 30.8 IU/L, respectively; P = .024). Two of 4 patients who underwent combination therapy with IFN and ribavirin during treatment with CsA and MMF obtained an HCV-negative status for over 24 weeks. CsA effectively prevents the progression of chronic hepatitis in HCV-positive renal transplant patients. A greater response rate can be expected by concurrent administration of CsA and MMF under IFN therapy.

Cyclosporin and Organ Specific Toxicity: Clinical Aspects, Pharmacogenetics and Perspectives

Cyclosporine (CsA) has considerably modified the graft survival in solid organ and bone marrow transplantations. It is also the treatment of choice in chronic diseases such as steroid resistance and/or dependence nephrotic syndrome and autoimmune-diseases, especially in those cases that require long term treatments. Renal toxicity is the major adverse effect of chronic CsA administration. Deterioration of renal function and renal histopathology are the basic elements of the diagnosis. Overall, available studies suggest a good degree of safety related to appropriate drug dosages even if they require an adequate degree of surveillance in case of rapid changes of renal functions and long term evaluation of renal pathology. CsA neurotoxicity is the second major problem that seems underestimated especially in case of subtle manifestations in children. The full blown picture of the acute form is characterized by convulsion and sudden alteration of mental function that are reversible upon drug withdrawal. The diagnosis is based on typical CT and MRI aspects of extensive bilateral white-matter abnormalities in the occipital region of the brain that mimics the posterior encephalopathy syndrome. Prospective evaluations of drug tolerance include renal histology in case of chronic renal toxicity and neuro-imaging to identify and block acute neurotoxicity.

Neonatal injections of cyclosporin enhance autoimmune diabetes in non-obese diabetic mice.

Since the modulation of the immune system at birth may influence the course of insulin-dependent (type 1) diabetes, we investigated whether neonatal injections of cyclosporin (CsA) to newborn non-obese diabetic (NOD) mice influence diabetes during later life. Two groups of 90 mice (45 female, 45 male) were injected intraperitoneally for the first 6 days of life with CsA (10 mg/kg per day) or with vehicle. In female NOD mice, the onset of diabetes was earlier and cumulative incidence was higher after neonatal treatment with CsA (P < 0.01). The incidence of diabetes was also dramatically enhanced in male NOD mice (P < 0.01), which normally display a very low disease incidence. Concomitantly, the severity of lymphocytic infiltration of the pancreatic islets was higher in female NOD mice neonatally treated by CsA (P < 0.02), and to a lesser extent in males, than in control mice. After administration of CsA to newborn NOD mice, there was a reduction (P < 0.01) of both CD4+CD8- and CD4-CD8+ thymocytes, whereas the number of double positive CD4+CD8+ thymocytes was increased. Concomitantly, Thy1-2+ cells in spleen were decreased (P < 0.01), and spleen cells expressing either CD3 molecule or alpha beta TCR complex were diminished (P < 0.01). Both CD4+ and CD8+ spleen T cells were depleted. By contrast, the low percentage of gamma delta TCR-expressing splenocytes was not modified. Numbers of MHC class 1+ or MHC class 2+ spleen cells were also depressed (P < 0.01). After neonatal injections of CsA, spleen cells showed a reduced response to concanavalin A (Con A) (P < 0.01). On the contrary, stimulation indices of splenocytes incubated with xenogeneic insulin-producing cell extracts were enhanced (P < 0.03). Proliferation indices of splenocytes to self class 2 antigens, generating suppressor cell activity, during syngeneic mixed lymphocyte reaction (SMLR) were significantly reduced (P < 0.01). Irradiated NOD mice were used as recipients for spleen cells from CsA-neonatally treated NOD mice. They displayed enhanced insulitis 2 weeks after transfer, and diabetes was successfully produced by 1 month after transfer in 50% of the recipients. By contrast, NOD mice which received control syngeneic spleen cells remained normoglycaemic, with only moderate islet infiltration which would be expected of NOD mice of this age. Thus, neonatal injections of CsA markedly enhance diabetes in both female and male NOD mice.(ABSTRACT TRUNCATED AT 400 WORDS)

Adhesion molecule expression in psoriatic skin lesions and the influence of cyclosporin A

Normal skin of healthy individuals and both lesional and uninvolved skin from patients with psoriasis before and after receiving cyclosporin A (CsA; 2.5 or 5 mg/kg per day) was examined by immunocytochemistry for differences in expression of adhesion-relevant epitopes. Normal, lesional and uninvolved skin all showed staining of basal keratinocytes for CD29 (the common beta chain of the beta 1-integrin family). No other adhesion molecule investigated was detected on structural components of normal skin. In uninvolved skin, weak expression of CD54 (intercellular adhesion molecule 1, ICAM-1) was noted on vascular endothelium. Uninvolved keratinocytes were found to stain with anti-CD58 (leucocyte function-associated antigen 3, LFA-3) and there was weak expression of CD11b (alpha chain of complement C3bi receptor) and CD11c (alpha chain of p150, 95 molecule) but not CD11a (leucocyte function-associated antigen 1, LFA-1, alpha chain) on those cells. In lesional skin, in addition to expression of CD58, there was also enhanced expression of CD11c. Weak expression of CD54 on keratinocytes was also observed. Lesional blood vessels were found to stain strongly with anti-CD54, CD29 and CD58. CD11a was expressed only on infiltrating mononuclear cells. CsA treatment produced marked clinical improvement, accompanied by the loss of CD54 expression on keratinocytes. However, despite the loss of T cells from lesional skin with CsA treatment, CD54 persisted on blood vessels. CsA was found to have no effect on keratinocyte expression of CD29, CD58 or CD11b and c. The persistence of CD54 on vascular endothelium and of adhesion molecule expression on keratinocytes, despite resolution of the skin lesions, may explain the universal and rapid recurrence of psoriasis on cessation of CsA administration.

Eficacia del mantenimiento con azatioprina sin ciclosporina oral tras un brote grave de colitis ulcerosa refractario a esteroides intravenosos

Intravenous (i.v.) cyclosporine (CsA) has proved effective in controlling acute attacks of ulcerative colitis unresponsive to IV steroids. After the initial response to i.v. CsA, two alternatives for maintaining remission have been proposed: either double or triple association with immunosuppressors. The aim of this study was to evaluate the effectiveness of i.v. CsA, its adverse effects, and the subsequent long-term effectiveness of azathioprine/6-mercaptopurine without oral CsA. Intravenous CsA was administered for 10 days, at a dose of 4 mg/kg per day, to 20 patients diagnosed with a severe attack of ulcerative colitis who did not respond to IV steroid treatment. Patients who responded to CsA and could be discharged were administered azathioprine or 6-mercaptopurine associated with a decreasing dose of oral steroids, without oral CsA. Sixty per cent (12/20) of the patients showed clinical-biological improvement after CsA administration, thus avoiding colectomy, and were discharged from hospital. Nine of the 12 responders (three withdrew from the study) were followed-up long term. Of these nine patients, four (44.4%) underwent colectomy, all before the sixth month of discharge. All adverse effects were mild, except for one death. Intravenous CsA is effective in inducing remission of ulcerative colitis in severe attacks resistant to i.v. steroids. When treatment with azathioprine is administered without oral CsA, patients requiring colectomy need this procedure within the first 6 months of discharge.

Effect of Multiple Oral Dosing of Fluconazole on the Pharmacokinetics of Cyclosporine in Healthy Beagles

Fluconazole (Fcz) is successfully used in human organ transplant patients as an antifungal therapy. However, Fcz can increase the cyclosporine (CsA) trough level and lead to CsA nephrotoxicity. In canine renal transplantation, CsA has been used as a major immunosuppressant, and it is important to control its trough level. However, the interaction of Fcz with CsA has not yet been reported in dogs. In this study, the effect of Fcz treatment on the pharmacokinetics of CsA in four healthy beagles was investigated using a four-period crossover design. The treatments included CsA alone (A), CsA + multiple-dose Fcz 50 mg (B), CsA + multiple-dose Fcz 25 mg (C) and CsA + single-dose Fcz 50 mg (D). Blood CsA concentrations were measured at 0.5, 1, 2, 4, 6, 8, 10, 12 and 24 hr after CsA administration. The AUC(0-12) and C(max) values for treatment B were significantly higher than those for the other treatments. In particular, the AUC(0-12) of treatment B was about two times higher than that of treatment A. Fcz administration did not significantly prolong the half-life or mean residence time of CsA. The results of our study show that administration of multiple therapeutic doses of Fcz can significantly increase the CsA blood concentration, which might partially depend upon the Fcz blood concentration. When Fcz is used in CsA-based canine renal transplantation, it may be necessary to adjust the CsA trough level by decreasing the dose.

Hormones thyroïdiennes et phénotype musculaire : proposition d'implication de nouvelles voies de régulation

Thyroid hormones (TH) are known to control development, body and muscle growth, as well as to determine muscle phenotype in the adult. TH affect muscle properties through nuclear receptors; they act either by a positive or a negative control on target genes that encode proteins accounting for contractile or metabolic phenotypes. Contractile activity and muscle load also affect muscle phenotype; several intracellular signaling pathways are involved in the transduction of signals related to contractile activity, including the calcineurin/NFAT pathway. Calcineurin activity is negatively controlled by MCIP-1 protein (modulatory calcineurin-interacting protein-1). We recently performed an experiment aimed at examining the specific and combined effects of the pharmacological calcineurin inhibition (using cyclosporin-A CsA administration) and thyroid hormone deficiency. The expected effects of CsA administration were only observed if TH were available, while thyroid deficiency totally blunted the muscle responses to calcineurin inhibition. In conditions of thyroid hormone deficiency, there was no response to the pharmacological inhibition of calcineurin, usually known to induce a slow-to-fast IIA transition associated with an enhancement of mitochondrial biogenesis in normothyroid rats. Moreover, thyroid deficiency markedly decreased the expression of MCIP-1 and MCIP-2 mRNA and proteins, two endogenous calcineurin inhibitors; such results clearly suggest that thyroid hormone and calcineurin pathways are interconnected.

Restoration of Endocrine Function and Fertility with Orthotopic Tubal—Ovarian Allotransplant as the Anatomical-Functional Unit in Rabbits

The aim of this study was to re-establish endocrine and reproductive function in tubal-ovariectomized rabbits using orthotopic tubal–ovary allotransplants (OT-OA). Fifty-five New Zealand White nonconsanguineous rabbits were used and allocated into five experimental groups: Each group comprised donors submitted to right salpingo-oophorectomy that served as the donated allograft. In group 1 no cyclosporin (CsA) was administered and rabbits were submitted to left salpingo-oophorectomy (LSO). Group 2 was the allotransplant group and did not receive CsA. Group 3 was the allotransplant group with CsA. They were submitted to bilateral salpingo-oophorectomy followed by OT-OA. CsA of 10 mg/kg/day was administered to rabbits for the first 21 days and 5 mg/kg/day for the remainder of the study. Group 4 received CsA just as for group 3 and was submitted to LSO. During the study the following were measured: estradiol (E2), progesterone (P4), follicle-stimulating hormone (FSH), luteinizing hormone (LH), and histopathological study of the uteri, tubes, and ovaries. Groups 1, 3, and 4 showed a significant increase in serum E2 and P4 levels corresponding to the second week of gestation, compared to group 2 (p < < x >.05). < i > Group < /i > 2 < i > showedasignificantincreaseinserumLHandFSHlevelsduringweek < /i > 10 < i > comparedtoserumLHandFSHlevelsingroups < /i > 1, 3, < i > and < /i > 4 (< /x > p <.05). In group 3, three rabbits did not reject the allotransplant, one rabbit became pregnant, and endocrine function was re-established in two rabbits. It can be concluded that OT-OA together with CsA administration re-establishes endocrine function and fertility.

면역억제제의 약물속도론적/약력학적 파라미터에 기초한 표현형과 유전형의 상관성

Cyclosporine (CsA) and tacrolimus (FK506) have a narrow therapeutic range, and their pharmacokinetic (PK) characteristic varies among individual. They are also substrates for cytochrome P450 (CYP) 3A4, 3A5 genes, and P-glycoprotein, the product of the multidrug resistance 1 (MDR1). The aims were to investigate the relationship between CYP3A and MDR1 genotypes and their PK parameters among healthy subjects. We investigated the genotype for CYP3A and MDR1 gene in human using a polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) method. After oral administration of CsA and FK506 (100 mg and 1 mg, respectively), whole blood samples were taken up to 24 hours. Blood CsA and FK506 concentrations were measured by LC/MS/MS. Each PK parameters were compared using Kruskal-Wallis test according to the CYP3A and MDR1 genotype. We found that the values of AVC for CsA were significantly different among CYP3A5 and MDR1 exon 26 (C3435T) genotypes (P=0.037 and P=0.049). On the other hand, the AUC for FK506 was significantly different only among CYP3A5 genotypes (P=0.013). The results clearly demonstrate the effects of CYP3A5 and MDR1 exon 26 on Cys and FK506 disposition.

A Prospective Cross-Over Study Comparing the Pharmacokinetics of Cyclosporine A and Its Metabolites After Oral Versus Short-Time Intravenous Cyclosporine A Administration in Pre–Heart Transplant Patients

Sometimes intravenous administration of cyclosporine (CsA) is essential before oral administration is possible. There are only a few reports available on the interindividual variability of CsA metabolism and different metabolite pattern depending on intravenous versus oral administration of CsA in heart transplant (HTx) patients. For effective inhibition of calcineurin we used a short infusion reaching peak concentrations after 2 hours. In a prospective cross-over study we compared the pharmacokinetics of CsA and its metabolites after oral (2.0 mg/kg body weight) versus intravenous (0.7 mg/kg body weight; 2-hour infusion) CsA administration (single test dose) in 7 pre-HTx patients. The pharmacokinetic parameters of CsA and its metabolites were analyzed using high-pressure liquid chromatography. The pharmacokinetic parameter area under the concentration time curve (AUC(0-infinity)) of CsA after intravenous administration was significantly lower (2903 ng*h*mL(-1)) than that after oral administration (4344 ng*h*mL(-1); P=.01). Peak concentrations, time to peak concentration, and terminal elimination half life were not significantly different. Short-time infusion of CsA resulted in a significant decrease in the AUC of the metabolites AM1 (3-fold), AM9 (10-fold), and AM1c (3-fold). A 2-hour infusion of CsA is just as effective as oral administration and the reduced amount of metabolites is advantageous for the patient.

Autologous graft-versus-host disease: harnessing anti-tumor immunity through impaired self-tolerance

The absence of a graft-versus-malignancy (GVM) effect may be responsible for the higher relapse rate seen after autologous hematopoietic cell transplantation (auto-HCT) compared with allogeneic hematopoietic cell transplantation (allo-HCT). Acute GVHD developing after allo-HCT, however, is associated with significant morbidity and mortality. An autoimmune syndrome similar to acute GVHD has been reported to occur after auto-HCT and has been termed the 'auto-aggression' syndrome or autologous GVHD (auto-GVHD). Auto-GVHD tends to be milder than classical GVHD, most commonly involves the skin (rarely the gastrointestinal tract, liver or both) and often is self-limited. Auto-GVHD has been reported to occur both spontaneously and in subjects receiving post transplant immune modulation with CsA, IFN-gamma or the combination. The development of auto-GVHD depends upon the derangement of self tolerance either through administration of post transplant CsA, depletion of regulatory T cells following the preparative chemoradiotherapy or both. Self-reactive CD8(+) T cells paradoxically are able to recognize a self peptide antigen presented by MHC class II molecules and appear to mediate the syndrome. Many clinical trials have been performed using CsA with or without IFN-gamma in an attempt to induce auto-GVHD. While many patients do indeed develop the syndrome, any associated anti-tumor effect remains questionable to date. New strategies to exploit auto-GVHD and enhance a GVM effect such as through the depletion of regulatory T cells or through use of newer immunomodulatory agents may improve the efficacy of auto-HCT.

Cyclosporine monitoring in the early post-transplant period in pediatric liver transplant recipients

Monitoring of CsA blood levels two h post-dose (C2) has shown a higher correlation to drug exposure than monitoring of trough levels (C0) at least in adults, but initial doses and target blood levels of CsA have yet to be established in pediatric transplant patients. The objectives of the study were to describe the pharmacokinetics of CsA administered by NGT in the first days after transplantation and the dose of Sandimmun Neoral required to achieve minimum therapeutic range blood levels. This study included 20 pediatric liver transplant recipients (mean age of 3.2 yr) treated with CsA administered by NGT from day one post-transplant until they were able to ingest oral medication. The study was continued until one yr of post-transplant follow-up. Eight h pharmacokinetic profiles were performed on days one, three, and five post-transplant to determine the minimum dose required to achieve the therapeutic range. All children received an initial dose of 15 mg/kg/day of CsA by NGT. Mean CsA doses administered on days one, three, and five were 16.8, 29.5, and 36.5 mg/kg/day, respectively. Mean C0 levels of 119, 310, and 337 ng/mL and mean C2 levels of 213, 753, and 888 ng/mL were obtained. No correlation was found between C0 and C2 levels and the AUC(0-8 h). Intravenous administration of CsA was required in 55% of patients. The biopsy-confirmed acute rejection rate was 45%, with graft and patient survival rates of 95 and 100%, respectively. Poor absorption of CsA in small children requires a considerable increase in dose. CsA exposure cannot be estimated by single C0 or C2 determinations in the early post-transplant period.

Cyclosporine Effects on the Antioxidant Capacity of Rat Renal Tissues

Cyclosporine (CsA) has been shown to improve long-term survival after organ transplantation. However, CsA therapy is associated with a variety of side effects, among which nephropathy is the major one. Recent studies have suggested increased oxidative stress as a cause of drug nephrotoxicity. Therefore, this study was designed to evaluate the effects of CsA administration on the antioxidant capacity of kidney tissue. Adult male Sprague-Dawley rats were randomly assigned into 2 groups: one group received CsA (25 mg/kg/d, IP for 2 weeks) and a control group (no CsA administration). After 2 weeks, the kidneys of the rats from both groups were removed under anesthesia. A 50 mg fresh kidney tissue sample was homogenized in ice-cold phosphate buffer. Total antioxidant capacity (Ferric Reducing Ability of Plasma [FRAP]) in the homogenates was assayed based on the Benzie spectrophotometric method. FRAP in the kidney tissues had been significantly decreased by 2 weeks of CsA administration when compared with control rats (P<.05). These data suggested that CsA administration may decrease the antioxidant capacity of renal tissues. More studies on the evaluation of the protective effects of antioxidant therapy against CsA nephrotoxicity are underway.

Acid-Base Status Determines Cyclosporine-Induced Hypercalciuria

Cyclosporine (CsA) causes tubular dysfunction characterized by polyuria, calcium wasting, distal tubular acidosis, and hyperkalemia. The hypercalciuria induced by CsA administration is associated with an inhibition of calbindin D(28k) expression. It has also been shown that chronic metabolic alkalosis increased the expression of Ca(2+) transport proteins accompanied by diminished urine Ca(2+) excretion. The aim of this study, therefore, was to determine the effect of acid-base status on CsA-induced hypercalciuria. Experiments were performed on male Sprague-Dawley rats. Metabolic alkalosis and acidosis were induced respectively by adding 0.28 mol/L NaHCO(3) and 0.28 mol/L NH(4)Cl in the drinking water for 7 days; control rats received regular tap water. Seven days after NaHCO(3) or NH(4)Cl administration, rats were treated with CsA (25 mg/kg, IP) daily for 14 days. To estimate glomerular filtration rate (GFR) over time, animals were placed in metabolic cages. Fractional urinary calcium excretion was determined by standard formula. The CsA group showed decreased serum calcium and increased fractional urinary calcium excretion compared with the control group. Creatinine clearance was also significantly reduced. Metabolic alkalosis alone did not affect GFR, but significantly prevented an increase in fractional urinary calcium excretion induced by CsA, whereas chronic metabolic acidosis resulted in the exact opposite effect. It is essential for nephrologists to fully understand the mechanisms of CsA-induced renal injury. In this study, metabolic alkalosis reduced CsA-induced hypercalciuria. Further studies are needed to elucidate whether this effect may be achieved pharmacologically by the expression of Ca(2+) transport proteins.

難治性ネフローゼ症候群患者に対するシクロスポリンの最適投与法

Cyclosporine (CsA) is considered to be a potential treatment for steroid-resistant nephrotic patients.The purpose of our study was to compare the pharmacokinetics and pharmacodynamics of CsA (microemulsion formulation,Neoral) between preprandial and postprandial dosing regimens in patients with refractory nephrotic syndrome.Twenty seven patients,who received Neoral once in the morning,were enrolled in this study.Neoral was administered to twelve and fifteen patients after (postprandial group) and 30 minutes before breakfast (preprandial group),respectively.Blood CsA concentrations were measured before (C0) and 1,2,3 and 4 hours after administration of CsA (C1-C4).The value of C1 in the preprandial group was higher than that in the postprandial group but the area under the concentration-time curve from 0-4 hours (AUC0-4) was not higher.While the values of C0,C1,C2,C3 and C4 were correlated with those of AUC0-4 in the preprandial group,only the value of C2 was correlated with AUC0-4 in the postprandial group.In the preprandial group,the rate of increase in serum albumin concentrations was significantly higher than in the postprandial group.However,the incidences of nausea and/or vomiting in the preprandial group were higher than those in the postprandial group.In conclusion,our results suggest that preprandial dosing regimens of CsA are more efficient than postprandial dosing regimens,although gastrointestinal symptoms have to be considered.

Myostatin as a Putative Downstream Gene Target of Calcineurin Signaling Associated with Muscle Growth Remodeling

Myostatin (Mstn) is a TGFβ family growth factor that negatively regulates skeletal muscle growth with its inhibition shown to cause marked increases in muscle size. We investigated a plausible role for calcineurin (Cn), a Ca2+/calmodulin-regulated phosphatase implicated in compensatory growth remodeling, in the regulation of Mstn using transgenic approaches that induced either constitutive activation or interference of Cn signaling. Mstn mRNA levels were lower in the muscles of transgenic mice displaying compromised Cn activity and higher in transgenic mice with enhanced Cn activity compared to wild-type mice. Chronic administration of pharmacological Cn inhibitors CsA or FK506 to mice resulted in lower muscle Mstn mRNA levels. RT-PCR revealed higher muscle mRNA expression of CnA β and γ isoforms in Mstn−/− mice perhaps as a compensatory response. Immunoflorescence labeling of muscle cross-sections showed more intense fiber decorating of the Cn target transcription factor NFATc1 in Mstn−/− mice compared to wild-type controls. These results suggest that myostatin may be a downstream target gene of Cn signaling in a manner associated with muscle growth remodeling and may itself regulate levels of Cn expression. (Funded by NSERC, CIHR and CRC to RNM)

Reduction of ciclosporin and tacrolimus nephrotoxicity by plant polyphenols

The immunosuppressants ciclosporin (cyclosporin A, CsA) and tacrolimus can cause severe nephrotoxicity. Since CsA increases free radical formation, this study investigated whether an extract from Camellia sinensis, which contains several polyphenolic free radical scavengers, could prevent nephrotoxicity caused by CsA and tacrolimus. Rats were fed powdered diet containing polyphenolic extract (0-0.1%) starting 3 days before CsA or tacrolimus. Free radicals were trapped with alpha-(4-pyridyl-1-oxide)-N-tert-butylnitrone (POBN) and measured using an electron spin resonance spectrometer. Both CsA and tacrolimus decreased glomerular filtration rates (GFR) and caused tubular atrophy, vacuolization and calcification and arteriolar hyalinosis, effects that were blunted by treatment with dietary polyphenols. Moreover, CsA and tacrolimus increased POBN/radical adducts in urine nearly 3.5 fold. Hydroxyl radicals attack dimethyl sulfoxide (DMSO) to produce a methyl radical fragment. Administration of CsA or tacrolimus with (12)C-DMSO produced a 6-line spectrum, while CsA or tacrolimus given with (13)C-DMSO produced a 12-line ESR spectrum, confirming formation of hydroxyl radicals. 4-Hydroxynonenal (4-HNE), a product of lipid peroxidation, accumulated in proximal and distal tubules after CsA or tacrolimus treatment. ESR changes and 4-HNE formation were largely blocked by polyphenols. Taken together, these results demonstrate that both CsA and tacrolimus stimulate free radical production in the kidney, most likely in tubular cells, and that polyphenols minimize nephrotoxicity by scavenging free radicals.