Renal transplantation. Strategies to prevent organ rejection--the role of an inter-regional reference center

This paper summarizes the role of the Inter-Regional Reference Center (RC) of the North Italy Transplant program (NITp), in coordinating a donor procurement and organ transplantation network, with a special focus on the strategies to minimize immunological risk and complications after transplantation. In the NITp, patients enrolled on the renal transplantation (RT) waiting list are typed for HLA-A,B,DRB1 antigens with a genomic method. They are periodically screened for the presence of lymphocytotoxic antibodies in their serum by the RC and their suitability to receive the transplant is checked periodically. Cadaver kidney allocation is ruled by a computerized algorithm, named NITK3, established in 1997, which aims at ensuring quality, equity, transparency and traceability during all the phases of the allocation decision-making process. NITK3 has been set up by the NITp Working Group on the basis of biological, medical and administrative criteria and it is periodically reviewed after the analysis of transplant results. In this paper, we show the results of a preliminary analysis of RTs performed from 1998 to 2002 in nine out of sixteen centers of the NITp area, which demonstrates the general quality of the NITp program in terms of patients and graft survival and the special attention to the patients at higher immunological risk.

Performance of different prediction equations for estimating renal function in kidney transplantation

Numerous formulas have been developed to estimate renal function from biochemical, demographic and anthropometric data. Here we compared renal function derived from 12 published prediction equations with glomerular filtration rate (GFR) measurement by plasma iohexol clearance as reference method in a group of 81 renal transplant recipients enrolled in the Mycophenolate Mofetil Steroid Sparing (MY.S.S.) trial. Iohexol clearances and prediction equations were carried out in all patients at months 6, 9 and 21 after surgery. All equations showed a tendency toward GFR over-estimation: Walser and MDRD equations gave the best performance, however not more than 45% of estimated values were within +/-10% error. These formulas showed also the lowest bias and the highest precision: 0.5 and 9.2 mL/min/1.73 m2 (Walser), 2.7 and 10.4 mL/min/1.73 m2 (MDRD) in predicting GFR. A significantly higher rate of GFR decline ranging from -5.0 mL/min/1.73 m2/year (Walser) to -7.4 mL/min/1.73 m2/year (Davis-Chandler) was estimated by all the equations as compared with iohexol clearance (-3.0 mL/min/1.73 m2/year). The 12 prediction equations do not allow a rigorous assessment of renal function in kidney transplant recipients. In clinical trials of kidney transplantation, graft function should be preferably monitored using a reference method of GFR measurement, such as iohexol plasma clearance.

Mycophenolate mofetil versus azathioprine for prevention of acute rejection in renal transplantation (MYSS): a randomised trial

BACKGROUND

Mycophenolate mofetil has replaced azathioprine in immunosuppression regimens worldwide to prevent graft rejection. However, evidence that its antirejection activity is better than that of azathioprine has been provided only by registration trials with an old formulation of ciclosporin and steroid. We aimed to compare the antirejection activity of these two drugs with a new formulation of ciclosporin.

METHODS

The mycophenolate steroids sparing multicentre, prospective, randomised, parallel-group trial compared acute rejections and adverse events in recipients of cadaver-kidney transplants over 6-month treatment with mycophenolate mofetil or azathioprine along with ciclosporin microemulsion (Neoral) and steroids (phase A), and over 15 more months without steroids (phase B). The primary endpoint was occurrence of acute rejection episodes. Analysis was by intention to treat.

FINDINGS

168 patients per group entered phase A. 56 (34%) assigned mycophenolate mofetil and 58 (35%) assigned azathioprine had clinical rejections (risk reduction [RR] on mycophenolate mofetil compared with azathioprine 13.7% [95% CI -25.7% to 40.7%], p=0.44). 88 patients in the mycophenolate mofetil group and 89 in the azathioprine group entered phase B. 14 (16%) taking mycophenolate mofetil and 11 (12%) taking azathioprine had clinical rejections (RR -16.2%, [-157.5% to 47.5%], p=0.71). Average per-patient costs of mycophenolate mofetil treatment greatly exceeded those of azathioprine (phase A 2665 Euros [SD 586] vs Euros 184 [62]; phase B 5095 Euros [2658] vs 322 Euros [170], p<0.0001 for both).

INTERPRETATION

In recipients of cadaver kidney-transplants given ciclosporin microemulsion, mycophenolate mofetil offers no advantages over azathioprine in preventing acute rejections and is about 15 times more expensive. Standard immunosuppression regimens for transplantation should perhaps include azathioprine rather than mycophenolate mofetil, at least for kidney grafts.

Evaluation of 84 elderly donors in renal transplantation

BACKGROUND

The use of elderly donors (ED) and dual kidney transplantation (DKT) procedures have become common in clinical practice. A correct evaluation of kidneys from ED is crucial to avoid unsuccessful transplantation or the use of DKT when a single transplant (ST) would be equally successful. The aim of this investigation was to assess the role of renal biopsy (RB) in the assessment of kidneys from ED.

PATIENTS AND METHODS

A total of 84 ED aged > or = 60 yr were evaluated. In 19 cases, the kidneys were not used, mainly because of atherosclerotic vascular lesions. A histological score (HS) from 0 to 12 was awarded, considering the proportion of glomerulosclerosis, tubular atrophy, interstitial fibrosis, and arterial and arteriolar narrowing. On the basis of the HS, 37 donors were selected for 40 ST and 21 for DKT, three were discarded. All recipients received triple-drug therapy based on calcineurin inhibitors, mycophenolate mofetil and steroids.

RESULTS

Primary non-function was observed in three of 40 ST and one of 21 DKT. Acute tubular necrosis occurred in 22/40 ST and in 11/21 DKT. Acute rejection occurred in 16/40 ST and four of 21 DKT. Renal function was satisfactory in both groups, with 1-yr S-Cr = 171 micromol/L and 137 micromol/L, respectively in the ST and DKT groups. One-year patient survival was 92% in ST and 100% in DKT; 1-yr graft function was 87% in ST and 95% in DKT.

CONCLUSION

The histological assessment of kidneys from ED enables a correct selection of kidneys for ST or DKT and prevents the transplantation of high-risk kidneys.

A comparative prospective study of two available solutions for kidney and liver preservation

BACKGROUND

Viaspan (University of Wisconsin [UW]) solution is the gold standard for abdominal organ preservation. Celsior (CEL) is an extracellular-type, low-potassium, low-viscosity solution, initially used for heart and lung preservation. We have performed a prospective multicenter study to compare the role of these cold-storage solutions on kidney and liver recovery after transplantation.

PATIENTS AND METHODS

From March 15, 2000 to December 31, 2001, 441 (172 CEL and 269 UW) renal transplants (RT) and 175 (79 CEL and 96 UW) liver transplants (LT) were included in the study.

RESULTS

Perfusate volume used was significantly lower in the UW group, being 4,732 +/- 796 mL versus 5,826 + 834 mL in the CEL group (P < 0.001). In LT, median total bilirubin serum levels were significantly higher at 5 and 7 posttransplant days in the UW group (90.6 and 92.3 micromol/L, respectively) as compared with CEL (51.3 and 63.4 micromol/L, respectively). After LT, primary nonfunction (PNF) rates in the CEL and UW groups were 3.8% and 4.2% (P = NS) respectively, with 1-year graft and patient survival being 83.3% versus 85.4% (P = NS) and 89.9% versus 90.6% (P = NS). After RT, delayed graft function (DGF) rates were 23.2% and 22.7% (P = NS), respectively; PNF rates were 1.9% and 1.7% (P = NS) respectively, with 1-year graft and patient survival being 92.3% versus 94.2% (P = NS) and 99.4% versus 97.7% (P = NS).

CONCLUSIONS

CEL solution was shown to be as effective as UW in both liver and kidney preservation. In LT patients, biliary function recovery is significantly better in the CEL group. CEL solution represents an efficacious option in multiorgan harvesting.

Potential clinical implications of substitution of generic cyclosporine formulations for cyclosporine microemulsion (Neoral) in transplant recipients

Cyclosporine (CsA) is a critical-dose drug for which a minor change in absorption can have important clinical implications. Generic formulations of CsA are becoming more widely available, but standard criteria for bioequivalence require only that a single study in healthy volunteers demonstrate that mean pharmacokinetic parameters fall within 80-125% of the mean values for Neoral, the reference formulation of CsA. However, CsA absorption is known to differ between healthy volunteers and transplant patients and between different types of transplant patients, such that standard bioequivalence testing may be inadequate to ensure interchangeability of CsA formulations in all patients. The limited available clinical evidence has shown that stable renal transplant patients receiving Neoral have a significant reduction in mean CsA trough level after transfer to the Cicloral formulation. Mean pharmacokinetic values have been reported as equivalent following transfer to Gengraft in one study, but mean CsA trough fell and mean serum creatinine rose significantly in a separate trial. The only clinical outcomes data available are from a retrospective study of de novo renal transplant patients, which reported a significantly higher incidence of biopsy-proven acute rejection in patents receiving Gengraf versus Neoral (39% versus 25%, P<0.05). Until robust clinical data demonstrate that different formulations of CsA are interchangeable, it is advisable to prescribe CsA by brand, and any transfer to a different CsA formulation should be undertaken with close supervision and only at the direction of the transplant physician.

Ureteral stenosis in HDAF pig-to-primate renal xenotransplantation: a phenomenon related to immunological events?

The aim of this study was to analyze the incidence of ureteral stenosis in a life-supporting human decay-accelerating factor (hDAF) transgenic pig-to-cynomolgus monkey kidney transplantation model and determine the role of possible immunological events in its pathogenesis. Thirty consecutive bi-nephrectomized cynomolgus monkeys received a kidney from hDAF transgenic pigs with or without a ureteral stent. Four monkeys were euthanized prematurely after transplantation. In the remaining 26 cases, the mean survival was 24 +/- 19 days. Except in one case, there was a close relationship between ureter and kidney in terms of type and severity of rejection. There were six ureteral stenoses; five were repaired by stent positioning and resurgery extended survival for an additional 16 +/- 10 days. The stenotic ureters showed diffuse acute humoral xenograft rejection (AHXR), while all cases with no or only focal signs of ureteral rejection never revealed ureteral obstruction. Use of a ureteral stent extends the survival of a xenografted primate, thereby helping to clarify the immunological events surrounding the onset of AHXR in kidneys in long-term xenograft recipients.

Everolimus with optimized cyclosporine dosing in renal transplant recipients: 6-month safety and efficacy results of two randomized studies

Two prospective, randomized studies evaluated everolimus 1.5 vs. 3 mg/day with steroids and low-exposure cyclosporine (CsA) (C2 monitoring) in de novo renal transplant patients. Everolimus dosing was adjusted to maintain a minimum trough level of 3 ng/mL. Study 1 (A2306; n=237) had no induction therapy; in Study 2 (A2307; n=256) basiliximab was administered (Days 0 and 4). The primary endpoint was renal function at 6 months. CsA C2 target levels, initially 1200 ng/mL in Study 1 and 600 ng/mL in Study 2, were tapered over time post-transplant. Median creatinine levels in Study 1 were 133 and 132 micromol/L at 6 months in the 1.5 and 3 mg/day groups, respectively, and 130 micromol/L in both groups in Study 2. Biopsy-proven acute rejection (BPAR) occurred in 25.0% and 15.2% of patients in the 1.5 and 3 mg/day groups in Study 1, and 13.7% and 15.1% in Study 2. Incidence of BPAR was significantly higher in patients with an everolimus trough <3 ng/mL. There were no significant between-group differences in the composite endpoint of BPAR, graft loss or death, nor any significant between-group differences in adverse events in either study. Concentration-controlled everolimus with low-exposure CsA provided effective protection against rejection with good renal function.

Application of cyclosporine in renal transplantation: experience at the University of Padua

Cyclosporine (CsA) therapy has evolved considerably since its introduction as the primary immunosuppressant drug in the early 1980s and its use in renal transplantation continues to expand globally. In the last 20 years, there have been significant advances in formulation design, therapeutic drug monitoring guidelines, and the emerging role of CsA-based combination therapies that have resulted in a substantial improvement in clinical outcomes in renal transplant recipients. The aim of this work is to review developments in the application of CsA in kidney transplantation at our Center in Padua and to evaluate the clinical outcome of our patients in the last 15 years in relation to the new trends in CsA management strategies.

Acute rejection and graft survival in renal transplanted patients with viral diseases

Transplanted patients are susceptible to viral infections; thus, the aim of this study was to evaluate the features of acute rejections and the outcome of the renal graft in transplanted patients with herpes virus diseases. Renal biopsies from 30 renal transplanted patients undergoing early acute rejection (type IA and IB according to the Banff 97 classification) were evaluated. In total, 15 of these patients experienced cytomegalovirus (CMV) or Epstein-Barr virus disease within the first year following transplantation (group I) and 15 patients showed no evidence of viral infection (group II). No significant differences between the groups in terms of age, male/female ratio, living/cadaveric donor ratio, cold ischemia time, HLA A-B matching, pretransplant panel reactive antibody test, occurrence of post-transplant tubular necrosis, plasma levels of cyclosporin A and mean percent increase of serum creatinine at the time of the biopsy were observed. In group I biopsies, the mean number of interstitial plasma cells, as well as the mean number of CD79a-positive cells (B lymphocytes and plasma cells) was significantly higher than in group II (P<0.01 and <0.01, respectively). There was a positive correlation between the number of infections and the number of plasma cells (P<0.05). In transplanted patients, CMV can trigger the formation of anti-endothelial cell antibodies, which have been proposed to play a role in antibody-mediated rejections. We investigated whether a deposition of C4d, a marker of antibody-mediated reactions, was present in renal peritubular capillaries. In group I C4d deposition was found in five cases, while in group II it was not observed (P<0.05). In group I, 7/15 patients developed chronic allograft nephropathy vs 1/15 patients in group II (P<0.05). The estimated 1-, 5- and 8-year cumulative graft survival rates were 80, 66 and 57%, respectively, in group I, while in group II the estimated 8-year cumulative survival rate was 100% (P<0.05). In conclusion, acute rejection biopsies of patients with viral infections displayed plasma cell infiltrates and, in several cases, C4d deposition. Our study suggests a role of B lymphocytes in the pathology of these rejections and confirms the association between viral infections and poor graft survival.

Biphasic behavior of the kinetics of 31P-containing metabolites in ischemic porcine kidneys

The assessment of kidney viability before transplantation (with a view of discarding nonviable organs) remains an obstacle to confidently extending organ harvesting to marginal donors. In the present study phosphorus magnetic resonance spectroscopy was used to monitor metabolic changes in (31)P-containing metabolites in isolated porcine kidneys. After various warm ischemia times, the organs were stored at 0 degrees C. Time-dependent changes in the phosphomonoester/inorganic-phosphate ratio were recorded at 0 degrees C were shown to follow a biexponential decay. The first-order kinetic rate constant of the short-time decay was strongly dependent on the warm ischemia time, a result that was discreted in terms of the underlying biochemistry. The metabolic events responsible for the dramatic decrease in phosphomonoester/inorganic phosphate ratio that occur immediately after organ perfusion and storage, suggest that any procedure to minimize organ damage must occur immediately after harvesting.

Incidence of cancer after kidney transplant: results from the North Italy transplant program

BACKGROUND

Patients undergoing kidney transplantation demonstrate a higher risk of developing cancer as the result of immunosuppressive treatment and concurrent infections.

METHODS

The incidence of cancer in a cohort of patients who underwent kidney transplantation between 1990 and 2000, and who survived the acute phase (10 days), was analyzed as part of the North Italy Transplant program.

RESULTS

A total of 3,521 patients underwent transplantation during a 10-year period in 10 of 13 participating centers; the length of follow-up after kidney transplant was 67.7+/-36.0 months. During the follow-up, 172 patients developed cancer (39 with Kaposi sarcoma, 38 with lymphoproliferative diseases, and 95 with carcinomas [17 kidney, 11 non-basal cell carcinoma of the skin, 10 colorectal, 8 breast, 7 gastric, 7 lung, 6 bladder, and 3 mesothelioma]). The average time to cancer development after transplant was 40.1+/-33.4 months (range 0-134 months). Twenty-four patients developed cancer within 6 months from the transplant (10 with carcinomas, 7 with Kaposi sarcoma, and 7 with lymphoproliferative diseases). Three patients demonstrated a second primary cancer. The average cancer incidence was 4.9%. The incidence of cancer was 0.01 per year. Independent determinants of cancer development were age, gender, and immunosuppressive protocol including induction. Ten-year mortality was significantly higher in patients with cancer (33.1%) than among patients without cancer (5.3%). The relative risk of death in subjects with cancer was 5.5 (confidence interval 4.1-7.4).

CONCLUSIONS

These preliminary data underline the importance of long-term surveillance of transplant recipients, choice of immunosuppressive treatment, and careful donor selection.

Methotrexate for immunosuppression in life-supporting pig-to-cynomolgus monkey renal xenotransplantation

Methotrexate (MTX) has been used successfully as an immunosuppressant in rodent xenotransplantation models, but the data generated so far with MTX in pig-to-baboon cardiac transplantation studies have been disappointing. The potential of this agent was consequently explored in a life-supporting pig-to-primate renal model using the cynomolgus monkey as the recipient species. Introductory in vitro and in vivo pharmacokinetic and pharmacodynamic studies with MTX were conducted in three cynomolgus monkeys. Subsequently, 10 cynomolgus monkey recipients of a life-supporting kidney from human decay-accelerating factor transgenic pigs were administered MTX intravenously according to three different regimens. All the animals also received cyclosporine A and steroids. In addition, mycophenolate sodium (MPS) was administered post-operatively in two of the three groups of transplanted animals. At clinically relevant concentrations, MTX is able in vitro to inhibit the mixed lymphocyte reactions (MLR) in cynomolgus monkeys. After intravenous administration, moreover, exposure of cynomolgus monkeys to MTX appeared to be higher than had been previously reported in baboons. Graft function was observed in the transplanted animals, which survived from 0 to 41 days. All but two animals revealed acute humoral rejection in the explanted graft and developed diarrhea. Diarrhea was the cause of euthanasia in five cases. It was unrelated to the administration of MPS and associated with severe histopathological signs of enteritis. This study demonstrates that the pharmacokinetic and pharmacodynamic profiles if MTX vary substantially between non-human primate species. In vitro, MTX has immunosuppressive properties in the cynomolgus monkey at clinically relevant concentrations. In vivo, MTX has a very narrow therapeutic window in cynomolgus monkeys, however, as it does in baboons. We conclude that MTX is scarcely effective as an immunosuppressant, be it for induction or maintenance, in pig-to-cynomolgus monkey renal xenotransplantation.

Plasma fibrinolytic capacity in renal transplant recipients: effect of steroid-free immunosuppression therapy

BACKGROUND

Cardiovascular disease is the most common cause of death among renal transplant recipients (RTRs). Impaired fibrinolytic capacity caused by an increase in plasminogen activator inhibitor type 1 (PAI-1) levels is involved in the onset of atherosclerosis and thrombotic complications. Long-term steroid treatment may induce arterial hypertension and metabolic and prothrombotic changes (including up-regulation of PAI-1 synthesis), which increase the cardiovascular risk. We evaluated plasma fibrinolytic behavior in two groups of RTRs treated with different immunosuppressive regimens.

METHODS

Twenty-seven RTRs were randomized to receive long-term (17 patients) or perioperative short-term (10 patients) steroids in addition to immunosuppression with cyclosporine A plus everolimus (Certican; Novartis, Basel, Switzerland) (7 patients) or FK506 plus mycophenolate mofetil (20 patients). In each patient, fibrinolytic capacity was studied with the 20-min venous occlusion test 1 and 6 months after transplantation. The following were assayed: euglobulin lysis time, tissue-type plasminogen activator antigen, and PAI-1 antigen and activity.

RESULTS

One month after transplantation, a severe impairment of fibrinolytic capacity, mainly caused by an increase in PAI-1 antigen and activity levels, was seen in patients with and without steroid treatment. Six months after transplantation, an improvement in fibrinolytic potential as the result of a decrease in PAI-1 levels was observed only in patients without steroid therapy. None of the steroid-treated patients demonstrated PAI-1 values correlating with body mass index, blood pressure, and metabolic parameters, thus confirming the effect of exogenous factors on PAI-1 expression. Moreover, all patients revealed a slight impairment of stimulated endothelial tissue-type plasminogen activator release, regardless of any steroid treatment, which was probably attributable to calcineurin inhibitor-induced endothelial dysfunction.

CONCLUSIONS

Our study suggests that steroid-free immunosuppression is associated with a better fibrinolytic capacity in RTRs. This finding may contribute toward reducing the risk of cardiovascular events.

Kidney transplant in Gitelman's syndrome. Report of the first case

This paper is the first report of a patient with Gitelman's syndrome who, after developing a chronic nephropathy leading to end-stage renal disease, underwent kidney transplantation. The clinical findings of this disease, which include hypokalemia, high angiotensin II and aldosterone levels, sustained hyporesponsiveness to the pressor action of angiotensin II and norepinephrine, normo/hypotension and hypovolemia; the clinical course after kidney transplantation highlights the importance and the need for carefully controlling the hemodynamic status of these patients. In fact, the persistence of normo/hypotension and hypokalemia, in the presence of increased levels of Ang II and aldosterone to which the transplanted kidney should normally respond, raises interesting questions about the mechanisms responsible for the regulation of patient's vascular tone and potassium homeostasis after transplantation, which could expose the patient to post-transplant hypoperfusive renal failure and its long-term complications.

The effects of vitamin D receptor polymorphism on secondary hyperparathyroidism and bone density after renal transplantation

Immunosuppresive treatment and secondary hyperparathyroidism (SHPT) are considered among the most important pathogenetic factors for postrenal transplant bone disease. The aim of this study was to investigate the relationships among vitamin D receptor (VDR) gene polymorphism, parathyroid hormone (PTH) levels, and bone density in renal transplant recipients. We enrolled 69 patients (47 men and 22 women; mean age, 47 +/- 11 years) who had undergone kidney transplantation 51 +/- 5 months before. All patients underwent an evaluation of the main biochemical parameters of bone metabolism as well as bone densitometry. VDR alleles were typed by a polymerase chain reaction (PCR) assay based on a polymorphic BsmI restriction site. When the patients were categorized according to the VDR genotype (BB, Bb, and bb), serum creatinine, and the cumulative doses of immunosuppressive drugs were similar across the groups. PTH levels higher than 80 pg/ml were found in 53.6% of the patients, with the highest values being detected in the bb VDR genotype (p < 0.05). PTH was significantly correlated to urinary type I collagen cross-linked N-telopeptide (NTx) values. Bone density was low in the whole population; however, spinal bone density was lower in the bb subgroup (p < 0.02). In the whole population, only PTH (p < 0.05) and body mass index (BMI; p < 0.01) were independent predictors of spinal bone density. When grouping the patients by the VDR gene polymorphism, only PTH continued to be an independent predictor of spinal bone density in the bb allele subgroup (R2 adj. = 0.17). We can conclude that the VDR genotype polymorphism affects bone density of renal transplant recipients via its effects on the severity of SHPT.

Combined liver-kidney transplantation in a 15-year-old boy with alpha1-antitrypsin deficiency

Alpha1-antitrypsin (1-AT) deficiency is the most common genetic cause of liver disease in infants and children. The major clinical manifestations include liver disease (primarily in children) and emphysema in adults. For patients who progress to cirrhosis and liver failure, liver transplantation provides a metabolic cure for the deficiency and presumably prevents the associated complications. Several case reports in the pediatric literature describe glomerulonephritis in the setting of severe 1-AT deficiency, but this association is less well documented in adults. End-stage chronic kidney disease is a rare finding in the literature and kidney transplantation is the treatment of choice. We report on a 15-year-old boy with 1-AT deficiency and consequent end-stage liver disease and membranoproliferative glomerulonephritis rapidly progressing to renal failure, who successfully underwent combined liver-kidney transplantation.