Cyclosporine Nephrotoxicity Research Articles

Lack of acute cyclosporine nephrotoxicity in late heart-transplant recipients

Background Cyclosporine induces daily renal hypoperfusion in subjects with normal atrial natriuretic peptide (ANP) levels, but its acute effects in heart transplant patients with increased ANP remain to be determined. Methods Cyclosporinemia and creatinine clearance were monitored during 7 hours following cyclosporine administration in 6 heart transplant patients. Results-conclusions No acute cyclosporine-induced decrease in creatinine clearance was observed after heart transplantation. These data suggest that maintenance cyclosporine dose may be less nephrotoxic than suspected and that increased ANP might protect the renal function late after heart transplantation.

Improvement of impaired renal function in heart transplant recipients treated with mycophenolate mofetil and low-dose cyclosporine.

Cyclosporine (CsA) nephrotoxicity is a common problem after cardiac transplantation. We have studied the impact of CsA dose reduction in association with mycophenolate mofetil (MMF) treatment on renal function in heart transplant recipients with suspected CsA nephrotoxicity (serum creatinine level >2 mg/dl). Twelve heart transplant recipients (11 men, 1 woman; 111 to 1813 days after transplantation) with CsA-based immunosuppression (plus azathioprine and/or steroids) and a serum creatinine level >2.0 mg/dl were started on a daily dose of 2000 mg of MMF. Dilated cardiomyopathy was the underlying disease in nine patients, ischemic cardiomyopathy in three patients. Mean patient age was 57 years (range 44-69 years). Azathioprine was discontinued and CsA slowly tapered. Creatinine clearance, serum creatinine level, urea nitrogen, and uric acid were monitored. CsA levels were measured, and CsA dose was adjusted for whole blood levels of 70-120 microg/L. Ten patients still had endomyocardial biopsies, whereas one had echocardiographic controls only. One grade 1B rejection episode according to ISHLT (International Society for Heart and Lung Transplantation) was observed until 1 year after the switch to MMF. One patient was excluded due to gastrointestinal side effects. Conversion from azathioprine to MMF with consecutive reduction of CsA in heart transplant recipients with CsA-impaired renal function improves renal function as evidenced by lower serum creatinine, urea nitrogen, uric acid, and higher creatinine clearance.

IS 3-HOUR CYCLOSPORINE BLOOD LEVEL SUPERIOR TO TROUGH LEVEL IN EARLY POST-RENAL TRANSPLANTATION PERIOD?

Cyclosporine dose is traditionally based on trough blood levels. Cyclosporine trough blood level correlates poorly with acute rejection and cyclosporine nephrotoxicity after renal transplantation. We determined whether cyclosporine blood level at any other time point is superior to cyclosporine trough blood level as a predictor of acute rejection and cyclosporine nephrotoxicity. Cyclosporine blood level was measured before (trough), and 1, 2, 3 and 4 hours after the dose in 156 initial renal transplant cases 2 to 4 days after the initiation of cyclosporine micro-emulsion formula administration. The cylosporine micro-emulsion dose was based on cyclosporine trough blood level targeting 250 to 400 microg./l. Regression analysis revealed that only delayed graft function (p = 0.007) and cyclosporine blood level after 3 hours (p = 0.008) predicted acute rejection. Mean cyclosporine trough blood level plus or minus standard error was not significantly different in patients with and without acute rejection (293+/-21 versus 294+/-11 microg./l.). Mean cyclosporine blood level after 3 hours was significantly lower in patients with acute rejection (1,156+/-90 versus 1,421+/-50, p = 0.008). Cases were divided into tertiles at levels after 3 hours (1,100 and 1,500 microg./l.). The group in which the level after 3 hours was less than 1,100 microg./l. had the highest acute rejection rate (22 of 50 patients, 44%) and a cyclosporine nephrotoxicity rate of 13% (7 of 52 patients). The group in which the level after 3 hours was 1,100 to 1,500 microg./l. had the lowest acute rejection rate (5 of 46 patients, 11%) without increased cyclosporine nephrotoxicity (7 of 52 patients, 13%). A level after 3 hours of greater than 1,500 microg./l. was associated with a rejection rate of 15% (7 of 47 patients) but significantly higher cyclosporine nephrotoxicity (16 of 52 patients, 30%). Cyclosporine blood level after 3 hours in the early post-transplantation period is associated with acute rejection and cyclosporine nephrotoxicity. A cyclosporine blood level range after 3 hours of 1,100 to 1,500 microg./l. is associated with an optimal outcome. Our data suggest that cyclosporine blood level after 3 hours may represent a better method of monitoring cyclosporine micro-emulsion dose than cyclosporine trough blood level. This hypothesis must be further studied in randomized trials.

Calcium antagonists and renal protection from cyclosporine nephrotoxicity: long-term trial in renal transplantation patients.

Cyclosporine (CsA) treatment in solid organ transplantation has represented one of the greatest advances in the past 20 years, reducing acute rejection and increasing long-term survival. However, CsA has an important side effect, producing renal vasoconstriction and systemic hypertension. The main histological findings in the kidney are vascular lesions in the endothelium and smooth muscle cells. On proximal tubule cells, severe atrophy, vacuolization and thickening of the basal membrane can be found. The main mechanisms of vasoconstriction are secondary to endothelium disorders, increasing vasoconstrictor substances like endothelin, thromboxane, free radicals, etc., and reducing vasodilator substances like nitric oxide and prostaglandins. CsA acute nephrotoxicity produces haemodynamic changes with minor histological lesions, which will disappear when the medication is discontinued. Long-term CsA nephrotoxicity has been widely discussed in the literature. For some authors, a limited number of patients can develop end-state renal failure but others did not suffer these complications. Nevertheless, it seems clear that high doses of CsA can produce renal lesion and renal insufficiency, being difficult to evaluate in renal transplant patients because of the frequent association with chronic rejection lesions. Several types of drugs have been used to treat CsA nephrotoxicity in renal transplant patients but calcium antagonists and angiotensin converting enzyme-inhibitors are the most frequently used, especially the former due to their effect on the afferent arteriole vasodilatation, their natriuretic properties and their reducing intracellular calcium. The greatest experience has been with nifedipine, but other drugs like verapamil, diltiazem, amlodipine, felodipine, isradipine, etc., have also been used. Lacidipine, a 1,4-dihydropiridine, has demonstrated a beneficial effect during the short term after renal transplantation, and a multicentre, multinational, double-bind, placebo-controlled clinical trial for the long term currently ongoing.

Short- and long-term post–renal transplant follow-up at Charles Nicolle Hospital

years, 56.5%; 31 to #45 years, 33.5%; and .45 years, 4%. Primary renal disease was chronic glomerulonephritis in 85 cases (42.5%), chronic pyelonephritis in 43 (21.5%), nephroangiosclerosis in 17 (8.5%), hereditary nephropathy in 11 (5.5%), and unknown in 44 (22%). Initial renal replacement therapy (RRT) was hemodialysis (HD) in 155 cases (77.5%), continuous ambulatory peritoneal dialysis (CAPD) in 24 (12%) and the two techniques combined in 21 (10.5%). For LRD, only first-degree relatives who gave their informed consent were accepted. All patients received ABO compatible and cross-match negative kidneys. At least 3 units of blood transfusions were given to 161 patients (80.5%) and cytotoxic antibodies were screened. All patients received a combination of prednisolone: 2 mg/kg/d on day 0, tapered to 0.2 mg/kg/d on day 90 and azathioprine at 125 mg/d. Antilymphocyte globulin (ALG) or antithymocyte globulin (ATG) was used as prophylactic treatment of graft rejection in 98 cases (48%) during the first 15 days. Cyclosporine was administered in 112 patients (56%) twice daily orally at 5 mg/d beginning on day 3 to 15 days in LRD transplants with one identical haplotype and after corticoresistant acute rejection episodes. The dosages were adjusted to clinical state and cyclosporine blood level (radioimmunoassay). Acute rejection episodes were treated with a combination of pulses of methylprednisolone and ALG/ATG in 75 cases. OKT3 was introduced in six cases when ALG/ATG failed to reverse the rejection. Mycophenolate mofetil was used in 11 cases with cyclosporine nephrotoxicity. The results were expressed as mean 6 standard deviation (SD). Comparisons were made with chi squared test for categorical variables and PLSD Fisher’ test for continuous variables. The survival rates were computed using the actuarial method. P , .05 was considered statistically significant. RESULTS The waiting time on dialysis was 28 6 22 months (1 to 119 months). For LRD, the donors were 96 (52.7%) siblings, 84 (46.2%) parents, and 2 children. HLA matching was 0 mismatches (MM) in 48 cases (26.4%) and 3 MM in 134 (73.6%). Their mean age was 38.6 6 13.4 (16 to 65) years. For CAD, HLA matching was 1 to 6 MM. The cytotoxic antibodies were positive in 27% of cases. Acute tubular necrosis (ATN) occurred in 26 cases (14.3%) of LRD and in 3 (16.7%) CAD. All those patients were hemodialyzed requiring 1 to 10 sessions, but all recovered. The difference between the two groups was not statistically significant (P 5 .07). The mean time of warm ischemia was 44 6 13 minutes for patients who have expressed ATN and 41.9 6 10.9 for those without ATN. The mean time of cold ischemia for CAD was 26.8 6 6 hours. Acute rejection was encountered in 16 (33.3%) cases of LRD with 0 MM, 80 (59.7%) cases of LRD with 3 MM, and 14 (77.8%) cases in the CAD group. The differences between the three groups were statistically significant (P , .0009). Complications Infectious complications were very common (86% of cases). Viral infections occurred in 40% of cases, mostly CMV (21%) and herpes (14%). No HIV infection was seen. Bacterial infections occurred in 60% of cases, mostly urinary tract infections (49%), septicemia (11.5%), and bronchopulmonary infections (5%). Six patients had scabies. Urologic complications occurred in 31 cases: 14 (7%) urinary leaks, 6 (3%) urinary stenosis, 2 ureteral compressions, 4 lymphoceles, 3 urinary lithiasis, and 2 urinary tuberculosis. Vascular complications were seen in eight cases: two arterial thrombosis, two venous thrombosis, three arteriovenous fistulae, and one perirenal hematoma. We noted recurrence of focal segmental glomerulosclerosis in six cases and glomerulonephritis de novo in two cases.

Expression of apoptosis regulatory genes in chronic cyclosporine nephrotoxicity favors apoptosis

Expression of apoptosis regulatory genes in chronic cyclosporine nephrotoxicity favors apoptosis. Chronic cyclosporine (CsA) nephrotoxicity is characterized by interstitial fibrosis, tubular dropout, and loss of cellularity in areas of fibrosis. Apoptosis was found to play a role in CsA-induced fibrosis. We evaluated the role of the death genes p53, Bax, and Fas-L (ligand), survival gene Bcl-2, interleukin-converting enzyme (ICE), and caspase-3. Salt-depleted rats were administered CsA 15 mg/kg/day or vehicle (VH) and were sacrificed at 7 or 28 days. Apoptosis was detected by TdT-mediated dUTP-biotin nick end labeling assay. p53 and Bax expressions were evaluated by Northern and Western blot analysis. Fas-L and Bcl-2 expressions were evaluated by immunofluorescence. In addition to ICE mRNA, caspase-3 enzymatic activity was assayed. Although no differences were seen at one week, apoptosis-positive cells increased with CsA at four weeks (P < 0.05) and correlated with tubular atrophy and interstitial fibrosis (r = 0.8, P < 0.05). CsA induced the expression of p53 (P < 0.05) and Bax (P < 0.01) and decreased that of Bcl-2 (P < 0.05). CsA up-regulated Fas-L expression (P < 0.001). ICE mRNA and caspase-3 activity were also increased (P < 0.01). The changes occurred as early as one week and remained statistically significant at four weeks. Specific apoptotic genes are increased in chronic CsA nephrotoxicity. The balance favors the induction of apoptosis. Increased apoptosis could explain the tubular dropout and loss of cellularity with fibrosis. This then may impair the ability of the tubulointerstitium to remodel. Apoptosis could also contribute to some of CsA immunosuppressive effects on activated lymphocytes.

Mycophenolate mofetil overlap in liver transplant recipients with chronic cyclosporine nephrotoxicity

Mycophenolate mofetil overlap in liver transplant recipients with chronic cyclosporine nephrotoxicity

Worsening Hepatic Encephalopathy Secondary to Zolpidem

Objective: To report a case of worsening hepatic encephalopathy secondary to ingestion of Zolpidem. Case Summary: A 41-year-old white man had postoperative complications 11 months after liver transplantation. Complications included narrowing of the choledochal anastomosis site, cyclosporine nephrotoxicity, and recurrent hepatitis C. Approximately seven months after transplantation, the patient experienced elevations in liver enzyme concentrations, lethargy, ascites, fever, chills, and nausea. Examination of a biopsy sample revealed recurrent hepatitis C. The patient's condition did not resolve despite administration of interferon alfa-2b, and his mental status began to deteriorate secondary to hepatic encephalopathy. One day before admission, the patient was given Zolpidem 5 mg for sleep; one hour after taking Zolpidem, he awoke in a stupor and was not oriented to place or time. When he became increasingly incoherent and verbally abusive, family members brought him to the emergency department. Although the patient exhibited mental status deterioration before receiving Zolpidem, considering the strong temporal relationship, his rapidly worsening state may be attributable to the drug. The patient subsequently required a second liver transplant in addition to a kidney transplant as a result of cyclosporine nephrotoxicity. The patient was not rechallenged with Zolpidem nor given flumazenil. Discussion: One pathophysiologic explanation for hepatic encephalopathy implicates endogenously produced benzodiazepine agonists. In patients with portal-systemic shunting, psychoactive compounds escape metabolism and are subsequently free to cross the blood-brain barrier. This mechanism is supported by reports of successful treatment of patients who have encephalopathy with flumazenil, a benzodiazepine antagonist. Hence, it follows that a benzodiazepine agonist could potentially exacerbate encephalopathic symptomatology. Zolpidem, although structurally unrelated to benzodiazepines, is a benzodiazepine agonist that binds preferentially to the benzodiazepine1 ω1 subtype of the γ-aminobutyric acid (GABAA) receptor complex. Therefore, administration of Zolpidem to patients with encephalopathy may worsen the condition by contributing to the accumulation of benzodiazepine agonists within the central nervous system. Conclusions: Although this patient's worsening mental status could be explained by a naturally evolving encephalopathic state, it is possible that Zolpidem exacerbated his decline. Existing evidence supports this view. First, an endogenously produced, benzodiazepine-related mechanism of hepatic encephalopathy is described in the literature. Second, benzodiazepine-like substances have been detected in the serum of patients with encephalopathy who have not received benzodiazepine therapy. Finally, clinical evidence supports the use of flumazenil in encephalopathic patients. Thus, it is likely that administration of Zolpidem hastened the mental decline of this patient.

Neoral monitoring by simplified sparse sampling area under the concentration-time curve: its relationship to acute rejection and cyclosporine nephrotoxicity early after kidney transplantation.

Cyclosporine (CsA) dosing is traditionally based on trough blood levels (C0) rather than area under the concentration-time curve (AUC), although AUC correlates better with posttransplantation clinical events. For Neoral, AUC based on limited sampling correlates closely with full 12-hr AUC. The purpose of our study was to correlate C0 with AUC based on CsA levels at 0, 1, 2, 3, and 4 hr after dose (PK0-4) and to compare this AUC with C0 in predicting acute rejection (AR) and acute cyclosporine nephrotoxicity (CsANT) in de novo first kidney transplant patients. PK0-4 was done 2-4 days after starting Neoral for 156 patients. All received CsA-based triple-drug immunosuppression without antibody induction. AUC was calculated as projected 12-hr (AUC0-12) and actual 4-hr (AUC0-4) from the PK0-4 using the parallel trapezoid rule. Neoral dosing was based on C0 not AUC. AUC was retrospectively compared with C0 as a predictor of AR and CsANT during the first 90 days. C0 correlated poorly with AUC0-12 and AUC0-4 (r=0.61 and r=0.42). C0 (mean+/-SEM) levels were not significantly different in 34 patients with and 109 without AR (293+/-21 vs. 294+/-11 microg/L, P=0.95). AUC0-12 and AUC0-4 were significantly lower in patients with than without AR (AUC0-12 9090+/-598 vs. 10608+/-336 microg x h/L, P=0.01; AUC0-4 3934+/-306 vs. 4802+/-166 microg.h/L, P=0.006). In stepwise regression analysis only AUC0-12 or AUC0-4 (P=0.03/P=0.02) and delayed graft function (P=0.007) predicted AR. AUC0-12, AUC0-4, and C0 were all significantly higher in patients with CsANT than without CsANT (AUC0-12 11746+/-650 vs. 10023+/-301 microg x h/L, P=0.01; AUC0-4 5270+/-358 vs. 4474+/-150 microg x h/L, P=0.01; C0 343+/-18 vs. 287+/-10 microg/L, P=0.01), but in stepwise regression analysis C0 was not an independent predictor of CsANT. Patients with AUC0-12 in the range of 9500 to 11500 microg x h/L or AUC0-4 between 4400 and 5500 microg x h/L had the lowest incidence of AR (13% and 7%, respectively) without significantly higher risk for CsANT. C0 correlates poorly with AUC based on PK0-4. Early AUC based on PK0-4 is more closely associated with AR and CsANT than is C0. Our data suggest that a target AUC0-12 of 9500-11500 or AUC0-4 of 4400-5500 microg x h/L may provide optimal Neoral immunosuppression.

Long-term maintenance of therapeutic cyclosporine levels leads to optimal graft survival without evidence of chronic nephrotoxicity.

Since the introduction of cyclosporine into clinical use, a major area of concern within the transplant community has been the fear of chronic nephrotoxicity. Although progressive renal damage does appear to occur in native kidneys of heart and liver transplant patients receiving cyclosporine, it has been our contention that its use is not a major cause of deterioration in renal allografts. We therefore undertook a study of 91 consecutive renal transplants performed over a three-year period with a minimum graft survival of 1 year and a follow-up of 7-9 years. Serial serum creatinine values, iothalamate clearances and cyclosporine levels were obtained at 3 months after transplantation and yearly thereafter. Biopsies were performed on all grafts that had failed as well as on the majority of patients with deteriorating renal function, and were interpreted by two nephropathologists. As measured by iothalamate clearances, 65% of the patients in this series exhibited absolutely stable renal function despite the maintenance of cyclosporine levels of more than 200 ng/ml for 7-9 years. Since these stable patients did not reveal any decline in renal function, it therefore follows that they did not experience chronic cyclosporine nephrotoxicity. Furthermore, none of the patients with declining renal function or with failed grafts showed any evidence of nephrotoxicity on biopsy. Chronic cyclosporine nephrotoxicity may be a cause of declining function or graft loss with renal transplant recipients, but if so, it is exceedingly rare.

Renal failure in the recipients of nonrenal solid organ transplants.

The increased success and availability of transplantation of solid organs other than kidneys has resulted in a large number of patients at risk for the usual medical complications of long-term immunosuppressive therapy. Acute and chronic renal failure play a critical role in the success of these

Antioxidants such as acetylcysteine may be useful for reducing cyclosporin nephrotoxicity,

Antioxidants such as acetylcysteine may be useful for reducing cyclosporin nephrotoxicity,

CONVERSION FROM AZATHIOPRINE TO MYCOPHENOLATE MOFETIL IN PEDIATRIC RENAL TRANSPLANT RECIPIENTS

710 Thirty-six renal transplant recipients, 22 boys and 14 girls, (grafted from 1980 to 1998) were converted from azathioprine (AZA) to Mycophenolate Mofetil (MMF). There were 7 living-related donor grafts and 1 combined kidney-liver transplantation. Mean age at transplantation was 8,8 years (range=1-18.5 yrs). Immunosuppressive tratment was AZA and prednisone (n=4); AZA, prednisone, cyclosporine (n=28); AZA, prednisone, FK506 (n=6). Initial doses of MMF were 600 mg/m2 b.i.d or 300 mg/m2 b.i.d for patients (pts) on FK506. Mean follow-up was 12.6 months (range=1-30). The pts were retrospectively divided into 3 groups according to the time of conversion to MMF related to the age of transplantation. Group 1 (n=8): Conversion to MMF was made during the first year post transplant (mean=4.1 mths). Two pts had cyclosporine nephrotoxicity, 1 had FK506 nephrotoxicity, 4 pts acute rejection (3 with FK506). All were biopsy proven. One pt had psychological intolerance to prednisone. Mean creatinine at the initiation of MMF was 128 μmol/l and decreased to 87 μmol/l after a mean follow-up of 14.3 mths. One pt had acute rejection 18 mths after MMF initiation. Group 2 (n=21): Conversion to MMF was made 1 to 10 yrs post transplant (mean=4.5 yrs). Seventeen pts had chronic transplant nephropathy (CTN) grade I to II, 2 had recurrent nephropathy, 1 had cyclosporine nephrotoxicity, and 1 had an anemia with AZA. Mean creatinine at initiation of MMF was 137 μmol/l. Six pts had a 10% to 25% decrease in creatinine level (follow-up 2.5 to 14 mths), creatinine level was unchanged in 12 pts, and 2 pts resumed dialysis. Anemia was corrected after MMF conversion. Group 3 (n=7): Conversion to MMF was made ≥10 years post transplant (mean=12.6 yrs). All pts had severe CTN. Mean creatinine at initiation of MMF was 255 μmol/l. One pt had a decrease in creatinine level (190 to 160 μmol/l), in 4 pts creatinine level remained unchanged, renal function deteriorated in 1, and 1 resumed dialysis due to non compliance. Of the 36 pts, 21 had 1 or more adverse events: diarrhea (16), nausea and vomiting (4), anemia (6), herpes zoster (2), pneumonia (1), urinary tract infection (1), HBV replication with cytolysis (1). These events led to discontinuation of MMF in 4 pts, interruption in 2, and dose reduction in 17. We conclude that conversion from AZA to MMF in pts with cyclosporine nephrotoxicity, acute rejection, or CTN grade I or II, results in stabilization or improvement in renal function in short term follow-up. However, conversion in pts with severe CTN offers no benefit. High incidence of MMF-related gastrointestinal adverse events necessitates reduced dosages in 50% of pts.

HIGHER CYCLOSPORINE LEVELS DECREASE KIDNEY REJECTION EPISODES WITHOUT INCREASING NEPHROTOXICITY

303 PURPOSE: Cyclosporine has become the mainstay of immunosuppression for renal transplant patients. Controversy persists, however, regarding the optimal level of cyclosporine that should be maintained for maximum immunosuppressive benefits and minimal toxicity. Because acute rejection episodes have been shown to be predictive of chronic rejection and graft loss, the goal of this study was to evaluate whether higher cyclosporine levels in the early post-transplant period would reduce the number of acute rejection episodes without significantly increasing nephrotoxicity. METHODS: This study retrospectively reviewed all patients who had living donor or cadaveric kidney transplants during a 5.5 year period. Cadaveric recipients were induced with low dose OKT3 (2 mg/day × 12 days). All patients were maintained on triple drug therapy and divided into three groups. Group 1 (n=62) was maintained at lower cyclosporine levels (150-250 ng/ml), prednisone, and azathioprine. Group 2 (n=32) and Group 3 (n=25) were maintained at higher cyclosporine levels (250-350 ng/ml), prednisone, and either azathioprine (Group 2) or MMF (Group 3). High, low, and mean cyclosporine levels and serum creatinine levels at 1, 3, 6, and 12 months were recorded. The frequency and severity of acute rejection episodes, all pre-treatment biopsy proven, were reviewed at 3 and 12 months. RESULTS: There were 119 kidney transplant patients entered into the study. There were no significant differences in race, sex, age, previous transplants, number of mismatches, or preformed antibodies between groups. There were significantly fewer rejection episodes in the groups maintained at higher cyclosporine levels (Groups 2 and 3) during the first 3 months (p<0.001) as well as the first 12 months (p<0.017). There was no significant difference in mean creatinine levels at any time interval between groups. No statistically significant difference was seen in the severity of rejection episodes as determined by Banff criteria. Patients with low cyclosporine levels (Group 1) tended to have an increased number of readmission days within the first 12 months following transplant compared with patients in Groups 2 and 3 (8.2 vs. 5.0, respectively). CONCLUSION: Maintenance of cyclosporine at higher levels can reduce the number of acute rejection episodes. This benefit can be achieved without increasing cyclosporine nephrotoxicity (as measured by serum creatinine levels) and may reduce the need for readmission to the hospital.

Transforming growth factor (TGF)-beta mimics and anti-TGF-beta antibody abrogates the in vivo effects of cyclosporine: demonstration of a direct role of TGF-beta in immunosuppression and nephrotoxicity of cyclosporine.

Cyclosporine (CsA) has been shown to induce the expression of transforming growth factor (TGF)-beta both in vitro and in vivo. It is hypothesized that the efficacy as well as the side effects of CsA are mediated by TGF-beta. This study was planned to investigate whether anti-TGF-beta mitigated and TGF-beta reproduced the in vivo effects of CsA to directly prove this hypothesis. B6AF1 (H2b/k.d) mice were divided into groups and received the following: CsA, vehicle (olive oil), CsA + anti-TGF-beta1 antibody, TGF-beta1, or vehicle phosphate-buffered saline/bovine serum albumin. All studies were carried out at 10 and 28 days after the last day of CsA administration with the exception of the exogenous TGF-beta experiments, which were performed 5 days after exogenous TGF-beta administration. The efficacy was studied by the anti-CD3-induced ex vivo proliferation of splenocytes measured by [3H]thymidine uptake; TGF-beta protein levels were quantified by ELISA. TGF-beta, collagen, and fibronectin gene expression was studied using reverse transcriptase-polymerase chain reaction, and histopathological analysis was made on periodic acid-Schiff- and trichrome C-stained thin kidney sections. CsA treatment resulted in decreased ex vivo proliferation of splenocytes, an increase in TGF-beta protein in the sera, and renal histopathological changes including tubular swelling, vacuolization, thrombotic microangiopathy, and increased expression of TGF-beta, collagen and fibronectin genes. All of these findings were blocked by anti-TGF-beta antibody. The study demonstrates the in vivo modulation of the effects of CsA by manipulating TGF-beta levels and suggests that TGF-beta at least in part mediates CsA's beneficial and detrimental effects.

In vitro effects of simvastatin on tubulointerstitial cells in a human model of cyclosporin nephrotoxicity.

To investigate the possibility that 3-hydroxy-3-methylglutaryl CoA (HMGCoA) reductase inhibitors ameliorate renal disease via direct effects on the tubulointerstitium, primary cultures of human proximal tubule cells (PTC) and renal cortical fibroblasts (CF) were exposed for 24 h to simvastatin (0.1-10 micromol/l) under basal conditions and in the presence of 1,000 ng/ml of cyclosporin (CsA), which we have previously shown to promote in vitro interstitial matrix accumulation at least partially via activation of local cytokine networks. Simvastatin, in micromolar concentrations, engendered cholesterol-independent inhibition of CF and PTC thymidine incorporation and cholesterol-dependent suppression of PTC apical Na+/H+ exchange (NHE) (ethylisopropylamiloride-sensitive apical 22Na+ uptake). Similarly, CF secretion of insulin-like growth factor-I (IGF-I) and IGF binding protein-3 were depressed, whereas CF collagen synthesis ([3H]proline incorporation) and PTC secretion of the fibrogenic cytokines, transforming growth factor-beta1, and platelet-derived growth factor were unaffected. A lower concentration (0.1 micromol/l) of simvastatin did not affect any of the above parameters under basal conditions but completely prevented CsA-stimulated CF collagen synthesis (control, 6.6 +/- 0.6; CsA, 8.3 +/- 0.6; CsA+simvastatin, 6.2 +/- 0.5%; P < 0.05) and IGF-I secretion (89.5 +/- 16.6, 204.7 +/- 57.0, and 94.6 +/- 22.3 ng. mg protein-1. day-1, respectively; P < 0.05). The results suggest that simvastatin exerts direct cholesterol-dependent and -independent effects on the human kidney tubulointerstitium. HMGCoA reductase inhibitors may ameliorate interstitial fibrosis complicating CsA therapy via direct actions on human renal cortical fibroblasts.

Two-year cyclosporin treatment in children with steroid-dependent nephrotic syndrome.

We describe a prospective study of 2-year moderate-dose cyclosporin (CS) treatment in 13 children with steroid-dependent minimal change nephrotic syndrome (MCNS). CS treatment was commenced at 100-150 mg/m2 per day after remission was attained with prednisolone therapy, was adjusted to a target trough level of 100 ng/ml, and was administered for 2 years. The number of relapses during CS treatment significantly decreased compared with before CS treatment, all patients were able to discontinue prednisolone therapy, and steroid toxicity was reduced; 54% of patients remained in remission during CS treatment. Renal biopsies performed before CS treatment all showed MCNS without tubulointerstitial lesions. Creatinine clearance and urinary beta 2-microglobulin levels during CS treatment were normal in all patients, but renal biopsies performed after CS treatment revealed chronic CS nephrotoxicity in 7 patients. Clinical data, including CS dose and CS trough blood levels, were not significantly different between patients with and without nephrotoxicity. In conclusion, 2-year moderate-dose CS treatment in children with steroid-dependent MCNS is effective in preventing relapse and decreasing steroid toxicity. This treatment can, however, result in a high incidence of chronic nephrotoxicity. Renal function is not a reliable indicator of chronic CS nephrotoxicity. Renal biopsy is therefore necessary to monitor chronic CS nephrotoxicity.

Renal complications after heart transplantation

THE PATHOGENESIS of chronic cyclosporine nephrotoxicity is unknown, although experimentally a model has been produced that mimics the clinical pathologic features of this lesion. This model is produced by salt depletion in a rat or mouse even with modest doses of cyclosporine. Said another way, clinically relevant cyclosporine doses in a salt-depleted animal can produce chronic cyclosporine nephrotoxicity, while massive pharmacologic doses in a salt-replete animal produces hemodynamic change without pathologic lesions. There is now a considerable body of evidence that the renin angiotensin system is involved directly or indirectly in the renal scarring process as well as the vascular lesions. Blockade of the renin angiotensin system with angiotensin-converting enzyme inhibitors or angiotensin II receptor antagonists can reverse the vasculopathy and interstitial fibrosis independent of changes in the glomerular filtration rate. There is also substantial evidence that angiotensin stimulates the production of increased interstitial matrix by its effects on transforming growth factor beta and its inhibition of matrix breakdown. Furthermore, cyclosporine and probably tacrolimus are known to reduce constitutive nitric oxide formation. Cyclosporine nephrotoxicity of the chronic variety is worsened by nitric oxide synthase inhibitors and is markedly improved by the infusion or administration of L-arginine. Finally, it has been shown recently that cyclosporine may induce renal tubular cell apoptosis by activation of the fas, fas-ligand pathway with the ultimate formation of caspases, which result in cell dropout and disappearance. How all of these pathways relate to clinical renal disease is best seen in successful heart transplant recipients. The frequency of cyclosporine nephrotoxicity is unknown and is very difficult to study in a renal transplant situation where rejection is always a confounding variable.

Individual or combined effects of enalapril and verapamil on chronic cyclosporine nephrotoxicity in rats.

Previous studies have demonstrated that enalapril and verapamil seem to attenuate the cyclosporine nephrotoxicity. However, the mechanisms have not been completely understood, especially on molecular events. The aim of this study was to examine the effect of individual or combined treatment on osteopontin, TGF-beta, endothelin-1 and procollagen alpha 1(I) mRNA expressions. Enalapril (50 mg/L in drinking water) and verapamil (0.5 mg/kg/day, subcutaneously), alone or in combination, were administered to rats with chronic cyclosporine nephrotoxicity (cyclosporine, 25 mg/kg/day, subcutaneously) (n = 5 each). Five rats treated with olive oil vehicle were used as control. After 4 weeks, biochemical parameters were measured, and renal cortical mRNA levels were evaluated by Northern blot analysis. Cyclosporine reduced renal creatinine clearance significantly and induced renal cortical osteopontin, TGF-beta, endothelin-1 and procollagen alpha 1(I) gene expressions around 13.5 +/- 1.3, 2.4 +/- 0.2, 1.5 +/- 0.1, 1.9 +/- 0.1 folds, respectively. Individual treatment with enalapril or verapamil significantly suppressed the osteopontin and TGF-beta mRNA expression, but not endothelin-1 and procollagen alpha 1(I). Combined treatment also inhibited the osteopontin and TGF-beta mRNA expression but there was no difference between combined and individual treatment. In conclusion, enalapril or verapamil significantly blunted the cyclosporine-induced osteopontin and TGF-beta gene expressions. However, combined treatment did not show any additive effect.

An Animal Model of Chronic Cyclosporine Nephrotoxicity

The development of a reproducible animal model that mimics CSA nephropathy in man has allowed the examination of the several proposed mechanisms of toxicity. While the precise mechanism remains to be defined, important clues have been provided and creative techniques for minimizing the adverse effects of this very valuable adjunct to transplant success have been identified.