Preservation of renal function during maintenance therapy with cyclosporine

During the last 20 years the management of cyclosporine (CsA) has improved due to the introduction of microemulsion technology, C2 monitoring, and combination with other new immunosuppressants. All these modifications have reduced the incidence of biopsy-proven acute rejection episodes to approximately 10%. However despite the wide experience, there are unanswered questions regarding CsA monitoring after the first year. Available clinical and histological data suggest that the therapeutic range to avoid nephrotoxicity or underimmunosuppression during the maintenance period is rather narrow. Furthermore, the combination of CsA with new immunosuppressants may modify the target CsA levels. Although the utility of C2 levels during the first year has been well characterized, there are few data on its utility for maintenance therapy, particularly the therapeutic range for C2 levels in patients receiving different immunosuppressive combinations. Since serum creatinine does not precisely reflect the progression of chronic allograft nephropathy, the efficacy of C2 monitoring during the maintenance period must be assessed not only by means of evaluation of renal function, but also histologic assessment using protocol biopsies.

Histologic findings in protocol biopsies performed in stable renal allografts under different immunosuppressive schedules

Protocol biopsies performed in stable renal allografts show different degrees of acute and chronic lesions. Histologic findings in protocol biopsies have been related to graft outcome. We evaluated histologic lesions observed in protocol biopsies performed in patients under different immunosuppression therapies. From June 1988 a protocol biopsy was performed at approximately 4 months in patients who fulfilled the following criteria: serum creatinine <300 micromol/L; stable renal function; and proteinuria <1 g/d. Histologic lesions were graded according to 1997 Banff criteria. For the present study we considered the following groups according to immunosuppressive schedule: (i) induction therapy with polyclonal or monoclonal antilymphocytic antibodies associated with cyclosporine and prednisone (n=201); (ii) cyclosporine, mycophenolate mofetil, and prednisone (n=127); and (iii) tacrolimus, mycophenolate mofetil, and prednisone (n=51). On protocol biopsy patients treated with tacrolimus displayed a lower acute score (0.61+/-1.01 vs 1.24+/-1.23 in group I, 1.28+/-1.41 in group II; P<.0001) and a higher proportion of normal biopsies (57.1% vs 41.9% in group I, 45.1% in group II; P=.016). A similar proportion of chronic lesions (chronic score of group I: 1.30+/-1.56; group II: 1.34+/-1.80; group III: 1.51+/-0.95; P=NS) was observed in the three groups. Protocol biopsies displayed fewer acute lesions in patients treated with tacrolimus. This result suggests that the efficacy of new immunosuppression schedules can be evaluated using the protocol biopsy as a surrogate marker of graft outcome.

Optimized protocol for linear RNA amplification and application to gene expression profiling of human renal biopsies

Gene expression analysis using high-density cDNA or oligonucleotide arrays is a rapidly emerging tool for transcriptomics, the analysis of the transcriptional state of a cell or organ. One of the limitations of current methodologies is the requirement of a relatively large amount of total or polyadenylated RNA as starting material. Standard array hybridization protocols require 5-15 micrograms labeled RNA. To obtain these quantities from small amounts of starting RNA material, RNA can be amplified in a linear fashion. Here we introduce an optimized protocol for rapid and easy-to-use amplification of as little as 1 ng total RNA. Our analysis shows that this method is linear and highly reproducible and that it preserves similarities as well as dissimilarities between normal and disease-related samples. We applied this technique to the RNA expression profiling of human renal allograft biopsies with normal histology and compared them to the profiles of renal biopsies with histological evidence of chronic transplant nephropathy or chronic rejection. Among others, complement component C1r was found to be significantly up-regulated in chronic rejection and chronic transplant nephropathy biopsies compared to normal samples, while fructose-1,6-biphosphatase showed lower-than-normal expression.

[Effect of cyclosporin and tacrolimus on lipoprotein oxidation after renal transplantation]

BACKGROUND

Cyclosporin A is a lipogenic immunosuppressor that can induce posttransplant hyperlipidaemia. Oxidation of low-density lipoprotein (LDL) has been recognized as a major atherogenic factor. Tacrolimus seems to be less lipogenic with an apparently better cardiovascular profile than CsA.

METHODS

We have studied the lipidic profile and the oxidation of HDL and LDL in 20 renal transplant patients, 12 male and 8 female, mean age 45 +/- 10 year, who where switched from CsA to tacrolimus due to CsA adverse effects. LDL were determined by ultracentrifugation. Oxidation study before and 6 months after conversion to tacrolimus was performed by adding CuSO4.

RESULTS

After conversion, systolic blood pressure (BP) decreased from 154 +/- 21 to 133 +/- 21 mm Hg (p = 0.008), diastolic BP from 97 +/- 13 to 77 +/- 15 mm Hg (p = 0.016), total cholesterol from 6.08 +/- 0.9 to 5.68 +/- 1.1 mmol/l (p = 0.02), LDL-chol from 3.29 +/- 1.01 to 2.96 +/- 0.3 mmol/l (p = 0.04) and apo-B lipoprotein from 1.42 +/- 0.28 to 1.15 +/- 0.34 mg/dl (p = 0.003). The oxidation of LDL improved after conversion: the initial dienic compounds decreased from 95 +/- 20 to 63 +/- 12 umol/g and the final DC from 207 +/- 56 to 107 +/- 35 umol/g. Lag-phase increased from 33 +/- 21 to 45 +/- 17 min (p < 0.05).

CONCLUSION

Tacrolimus has improved hyperlipidaemia in our cyclosporin previously treated patients and increased the resistance to oxidation of high and low-density lipoproteins.

Serial protocol biopsies to quantify the progression of chronic transplant nephropathy in stable renal allografts

AIM

To evaluate the utility of intimal thickness and interstitial width as a primary efficacy variable in the design of clinical trials aimed to modify the natural history of chronic allograft nephropathy.

METHODS

A donor and a 4-month protocol biopsy were evaluated in 40 stable grafts according to the Banff schema. In 27 patients, a second protocol biopsy was done at 1 yr. Arterial intimal volume fraction (Vvintima/artery) and cortical interstitial volume fraction (Vvinterstitium/cortex) were estimated with a point counting technique.

RESULTS

Chronic Banff scores increased during follow-up, while acute scores reached its peak at 4 months. Vvintima/artery and Vvinterstitium/cortex significantly increased at 4 months, but not at 1 yr. Vvintima/artery at 4 months correlated with donor Vvintima/artery (r = 0.57, p < 0.001), histocompatibility (r = 0.38, p = 0.01) and serum cholesterol (r = 0.31, p = 0.047). Vvinterstitium/cortex at 4 months correlated with recipient body surface area (r = 0.44, p = 0.004) and delayed graft function (p = 0.016). Power calculations showed that Vvintima/artery and Vvinterstitium/cortex allow an important reduction in minimum sample size of a hypothetical trial aimed to prevent chronic allograft nephropathy.

CONCLUSIONS

Intimal thickening and interstitial widening progresses rapidly during the first 4 months after transplantation and slowly thereafter. These parameters can be considered as a primary efficacy variable in trials aimed to prevent chronic allograft nephropathy.

Prevention and management of late renal allograft dysfunction

Chronic allograft nephropathy is the leading cause of return to dialysis after transplantation. At present, no efficient therapies are available to modify the natural history of chronic allograft nephropathy, mainly because of difficulties in designing prospective clinical trials to prevent or treat this entity. The main risk factors for chronic allograft nephropathy, the utility of protocol biopsies in the design of trials, and different strategies to prevent or treat this problem are reviewed.

Protocol renal allograft biopsies and the design of clinical trials aimed to prevent or treat chronic allograft nephropathy

BACKGROUND

The minimum sample size to perform a clinical trial aimed to modify the natural history of chronic allograft nephropathy (CAN) is very large. Since the presence of chronic tubulointerstitial damage in renal protocol biopsy specimens is an independent predictor of late outcome, we evaluated whether protocol biopsies could facilitate the design of trials aimed to prevent or treat CAN.

METHODS

Two hundred eighty-two protocol biopsy specimens were obtained 3 months after transplantation in 280 patients with serum creatinine levels <300 micromol/L, proteinuria <1000 mg/day, and stable function. The specimens were evaluated according to the Banff criteria.

RESULTS

Graft survival depended on the presence of CAN and renal transplant vasculopathy (RTV). Thus, biopsy specimens were classified as: (a) no CAN (n=174); (b) CAN without RTV (n=87); and (c) CAN with RTV (n=21). Graft survival at 10 years was 95%, 82%, and 41%, respectively (P=0.001). Total serum cholesterol before transplantation was 4.5+/-1.1, 4.6+/-1.1, and 5.3+/-1.6 mmol/L, respectively (P=0.009) and it was the only predictor of RTV. Power analysis (beta=20%, alpha=5%) was done to evaluate whether protocol biopsies can facilitate the design of clinical trials aimed either to prevent or treat CAN. We showed that the most feasible approach would be to use the presence of CAN as the primary efficacy end point in a prevention trial. To demonstrate a 50% reduction in the incidence of CAN at 3 months, 570 patients would be required.

CONCLUSIONS

Protocol biopsies may allow a reduction of sample size and especially the time of follow-up in a trial aimed to prevent CAN.

Fluvastatin and low-density lipoprotein oxidation in hypercholesterolemic renal transplant patients

BACKGROUND

Hyperlipidemia contributes to the development and progression of vascular disease in organ transplant patients. Oxidative modification of low-density lipoproteins (LDLs) has been suggested as a key event in early atherogenesis.

METHODS

We conducted a pilot study in renal transplanted patients with persistent hypercholesterolemia above 6.5 mmol/liter. We studied the LDL oxidation before and after one year of fluvastatin treatment. Twenty patients (12 males and 8 females, 46 +/- 10 years old) who received a kidney transplant 24 +/- 18 months before the study were treated with fluvastatin (20 mg/day for 12 weeks). Patients with a total cholesterol under 6.3 mmol/liter continued to receive 20 mg/day for another 40 weeks (group I, N = 10). Nine patients with a total cholesterol above 6.3 mmol/liter received 40 mg/day for a further 40 weeks (group II).

RESULTS

Cyclosporine levels did not experience a significant variation. Total and LDL cholesterol decreased significantly in both groups (21.7 and 27.9% in group I, 18.3 and 27.2% in group II, respectively). The lag-phase time, which was significantly enlarged before fluvastatin treatment in the patients with respect to the controls (N = 18, 82 +/- 45 vs. 50 +/- 8 min) was shortened after one year of fluvastatin treatment (64 +/- 24 vs. 50 +/- 8 min, P = 0.04). Fluvastatin was stopped in only one patient because of nausea and vomiting. Transaminases and creatin-phospho-kinase were not altered. All of the patients maintained a functioning graft during the study period.

CONCLUSIONS

Fluvastatin significantly reduced total and LDL cholesterol, without interferences with cyclosporine A through levels. Fluvastatin has not demonstrated an antioxidant effect in our renal hypercholesterolemic transplant patients.

Donor age and delayed graft function as predictors of renal allograft survival in rejection-free patients

BACKGROUND

Transplant recipients of kidneys harvested from old donors have a high incidence of delayed graft function (DGF) and a poor graft outcome. This result is partly explained by the increased incidence of acute rejection in patients suffering from DGF. However, the long-term impact of donor age and DGF in rejection free renal transplants is not well established. The aim of the present work is to evaluate the impact of donor age and DGF on long-term outcome in renal transplants with or without acute rejection.

PATIENTS

We review all cadaveric kidney transplants performed in our centre between April 1984 and December 1995 treated with a cyclosporin-based immunosuppression.

RESULTS

Five hundred and ninety-five patients were included. The overall incidence of DGF was 29.1%, and this event was associated with an increased donor age and cold ischaemia time. Univariate and multivariate analysis showed that graft loss was associated with acute rejection (relative risk (RR) 2.24, 95% confidence interval (CI) 1.62-3.01); DGF (RR 1.83, 95% CI 1.32-2.54); donors >50 years (RR 1.65, 95% CI 1.13-2.38); and retransplantation (RR 1.52, 95% CI 1.01-2.31). In rejection-free patients there were two independent predictors of graft failure: donor >50 years (RR 2.40, 95% CI 1.45-4.01); and DGF (RR 2.42, 95% CI 1.53-3.84).

CONCLUSIONS

Regardless of the presence of acute rejection, delayed graft function amplifies the detrimental effect of advanced donor age on long-term graft outcome.

Low-dose cyclosporine and mycophenolate mofetil in renal allograft recipients with suboptimal renal function

BACKGROUND

Cyclosporine (CsA) nephrotoxicity can be identified by functional changes and chronic renal damage. CsA-associated renal fibrosis has been related to the overproduction of transforming growth factor (TGF)-beta1, a fibrogenic cytokine. Mycophenolate mofetil (MMF) may allow CsA dose reduction without increasing the risk of rejection.

METHODS

We studied the impact of CsA dose reduction in association with MMF on renal function and TGF-beta1, production in 16 long-term renal allograft recipients with suspected CsA nephrotoxicity. Two grams/day of MMF were introduced, and CsA dose was reduced to reach whole-blood levels between 40 and 60 ng/ml within 1 month. CsA dose and levels, renal function parameters, and platelet-poor plasma TGF-beta1 levels were evaluated before and 6 months thereafter.

RESULTS

MMF allowed a decrease in both the mean dose of CsA (3.8+/-1.35 vs. 2.2+/-0.73 mg/kg/day; P<0.01) and CsA levels (148+/-36 vs. 53+/-19 ng/ml; P<0.001). The reduction of CsA was associated with a decrement of serum creatinine levels (210+/-46 vs. 172+/-41 micromol/L; P<0.001) and an increase in both the glomerular filtration rate (32.9+/-12 vs. 39.1+/-14 ml/min/1.73 m2; P<0.02) and renal plasma flow (195+/-79 to 218.6+/-74.02 ml/min/1.73 m2; P<0.02). There was a reduction in plasma TGF-beta1 levels (4.6+/-4.2 vs. 2.0+/-1.4 ng/ml; P=0.003) and CsA levels correlated with TGF-beta1 (r=0.536, P=0.002). No rejection episodes occurred, and an improvement in both systolic (149+/-13 vs. 137+/-12 mmHg; P<0.01) and diastolic blood pressure (89+/-14 vs. 83+/-10 mmHg; P<0.04) were observed.

CONCLUSIONS

These short-term results show that MMF introduction allows a CsA dose reduction, which improves renal function, reduces TGF-beta1 production, and improves the control of hypertension, without increasing the incidence of acute rejection.

Incidence of leukopenia and cytomegalovirus disease in kidney transplants treated with mycophenolate mofetil combined with low cyclosporine and steroid doses

Mycophenolate mofetil (MMF) combined with conventional cyclosporine and steroids doses efficiently prevents acute rejection in kidney transplants. However, this regimen has been associated with an increased incidence of cytomegalovirus (CMV) disease and leukopenia, specially in patients receiving MMF at 3 g/d, suggesting that the combination of two powerful immunosuppressants carries the risk of overimmunosuppression. For this reason, we treated a group of patients with MMF 3 g/d combined with low cyclosporine and steroids doses. Eighty-two kidney transplants performed at two centers and enrolled in the European Mycophenolate Mofetil Cooperative Study were randomized to receive: A) placebo (n = 27); B) MMF 2 g/d (n = 27); and C) MMF 3 g/d (n = 28). In this double blind study all patients received cyclosporine and steroids at conventional doses. Fifteen kidney transplants enrolled in an MMF open pharmacokinetic study were treated with MMF 3 g/day combined with low cyclosporine and steroid doses (group D). Efficacy was evaluated as the incidence of biopsy proven acute rejection, and safety focused on CMV disease and leukopenia. Patients receiving MMF showed a low incidence of biopsy proven rejection (B) 18.5%; C) 10.7%; and D) 13.3%). Patients of group C had a high incidence of CMV disease (35.7%) when compared with the other groups (lower than 8%). Incidence of leukopenia was higher in patients treated with MMF (B) 25.9%; C) 39.3%; and D) 40%) than in placebo treated patients (7.4%). Patients in group (C) displayed leukopenia mainly in the context of CMV disease, while patients of group (D) had leukopenia not related to CMV infection. All patients of group (D) who presented leukopenia recovered after MMF reduction dose, while in group (C) there were 5 out of 28 patients who required MMF withdrawal. We propose that a reasonable approach to take advantage of a powerful non-nephrotoxic immunosuppressant such as MMF, could be the administration of this drug at 3 g/d from the time of transplantation combined with low CsA and steroid doses.

Recipient body surface area as a predictor of posttransplant renal allograft evolution

BACKGROUND

The aim of the present study was to analyze whether minor differences in recipient body surface area have any predictive value on renal allograft evolution.

METHODS

For this study, we considered 236 pairs of recipients who received a kidney from the same donor at our center between March 1985 and December 1995. Pairs in whom at least one patient presented any of the following events were excluded: graft loss during the first year of follow-up, diabetes mellitus, noncompliance with treatment, chronic pyelonephritis, and recurrent or de novo glomerulonephritis. Recipients of each pair were classified as large or small according to their body surface area (BSA). The percentage difference of BSA in each pair was calculated, and two cohorts of pairs were defined: BSA difference < or = 10% (n=76 pairs) and BSA difference >10% (n=70 pairs).

RESULTS

The large recipients of the cohort with a BSA difference >10% showed a higher incidence of posttransplant delayed graft function (22/70 vs. 12/70, P=0.075), hypertension at 1 year of follow-up (51/70 vs. 35/70, P=0.006), and a higher serum creatinine level at 1-year follow-up (173 vs. 142 micromol/L, P=0.003), whereas in the cohort with a BSA difference < or = 10%, posttransplant evolution in large and small recipients was not different. Multivariate analysis showed that recipient BSA was an independent predictor of delayed graft function, posttransplant hypertension, and serum creatinine at 1-year follow-up.

CONCLUSIONS

Relatively small differences in recipient BSA influence renal allograft evolution. Consequently, our data support that recipient size should be taken into consideration for renal allograft allocation.