Interferon Gamma ELISPOT Testing as a Risk-Stratifying Biomarker for Kidney Transplant Injury: Results From the CTOT-01 Multicenter Study.

Previous studies suggest that quantifying donor-reactive memory T cells prior to kidney transplantation by interferon gamma enzyme-linked immunosorbent spot assay (IFNγELISPOT) can assist in assessing risk of posttransplant allograft injury. Herein, we report an analysis of IFNγELISPOT results from the multicenter, Clinical Trials in Organ Transplantation-01 observational study of primary kidney transplant recipients treated with heterogeneous immunosuppression. Within the subset of 176 subjects with available IFNγELISPOT results, pretransplant IFNγELISPOT positivity surprisingly did not correlate with either the incidence of acute rejection (AR) or estimated glomerular filtration rate (eGFR) at 6- or 12-month. These unanticipated results prompted us to examine potential effect modifiers, including the use of T cell-depleting, rabbit anti-thymocyte globulin (ATG). Within the no-ATG subset, IFNγELISPOT(neg) subjects had higher 6- and 12-month eGFRs than IFNγELISPOT(pos) subjects, independent of biopsy-proven AR, peak PRA, human leukocyte antigen mismatches, African-American race, donor source, and recipient age or gender. In contrast, IFNγELISPOT status did not correlate with posttransplant eGFR in subjects given ATG. Our data confirm an association between pretransplant IFNγELISPOT positivity and lower posttransplant eGFR, but only in patients who do not receive ATG induction. Controlled studies are needed to test the hypothesis that ATG induction is preferentially beneficial to transplant candidates with high frequencies of donor-reactive memory T cells.

Multicenter validation of urinary CXCL9 as a risk-stratifying biomarker for kidney transplant injury.

Noninvasive biomarkers are needed to assess immune risk and ultimately guide therapeutic decision-making following kidney transplantation. A requisite step toward these goals is validation of markers that diagnose and/or predict relevant transplant endpoints. The Clinical Trials in Organ Transplantation-01 protocol is a multicenter observational study of biomarkers in 280 adult and pediatric first kidney transplant recipients. We compared and validated urinary mRNAs and proteins as biomarkers to diagnose biopsy-proven acute rejection (AR) and stratify patients into groups based on risk for developing AR or progressive renal dysfunction. Among markers tested for diagnosing AR, urinary CXCL9 mRNA (odds ratio [OR] 2.77, positive predictive value [PPV] 61.5%, negative predictive value [NPV] 83%) and CXCL9 protein (OR 3.40, PPV 67.6%, NPV 92%) were the most robust. Low urinary CXCL9 protein in 6-month posttransplant urines obtained from stable allograft recipients classified individuals least likely to develop future AR or a decrement in estimated glomerular filtration rate between 6 and 24 months (92.5-99.3% NPV). Our results support using urinary CXCL9 for clinical decision-making following kidney transplantation. In the context of acute dysfunction, low values can rule out infectious/immunological causes of injury. Absent urinary CXCL9 at 6 months posttransplant defines a subgroup at low risk for incipient immune injury.

Clinical predictors of proteinuria after conversion to sirolimus in kidney transplant recipients.

Proteinuria is an increasingly recognized effect of sirolimus (SRL) therapy in kidney transplant recipients. Predictors of proteinuria after conversion to SRL are not well described, and in particular the risk in African-American (AA) kidney recipients is unknown. We sought to analyze risk factors for proteinuria with SRL therapy in a cohort of 39 patients (44% AA) converted from tacrolimus to SRL at a mean time of 4 months posttransplantation. Patients were maintained on therapy with mycophenolate mofetil while most patients underwent early steroid withdrawal. Urinary protein to creatinine ratio (Up/cr) at a mean of 14 months postconversion increased to > or =500 mg/g in 65% of AAs versus 14% of non-AAs (p = 0.001). Mean arterial blood pressure at the time of conversion and pretransplant proteinuric kidney disease were also predictors of proteinuria after SRL conversion. In conclusion, AAs appear to be at high risk for proteinuria and should be monitored closely after conversion to SRL in calcineurin inhibitor sparing protocols.

Differential pharmacokinetic interaction of tacrolimus and cyclosporine on everolimus.

OBJECTIVE: We characterized the pharmacokinetics of tacrolimus and everolimus in a combined immunosuppressive regimen. METHODS: This was an open-label exploratory trial in eight maintenance renal transplant patients with calcineurin inhibitor intolerance initially receiving mycophenolate mofetil (MMF) and tacrolimus. At enrollment, MMF was discontinued and replaced with everolimus 1.5 mg twice a day in study period 1 (days 1 to 10). In period 2 (day 11 to month 3), tacrolimus dose was reduced by half. RESULTS: At study entry tacrolimus trough level (C0) was 7.9 +/- 3.9 ng/mL and area under the curve over a dosing interval (AUC) was 132 +/- 56 ng x h/mL. The addition of everolimus in period 1 did not change tacrolimus exposure: C0 8.4 +/- 4.0 ng/mL, AUC 134 +/- 70 ng x h/mL. Everolimus pharmacokinetics in the presence of tacrolimus in period 1 were: C0 3.3 +/- 1.2 ng/mL, Cmax 10.4 +/- 5.1 ng/mL, AUC 58 +/- 20 ng x h/mL. When compared to pharmacokinetic data from a previous study in 47 renal transplant patients receiving everolimus at the same fixed dose (1.5 mg twice a day) with cyclosporine, everolimus exposure was 2.5-fold higher with cyclosporine relative to the data in this study with tacrolimus. After tacrolimus dose reduction in period 2, there was no clinically relevant change in everolimus exposure: C0 3.0 +/- 1.1 ng/mL, Cmax 8.2 +/- 1.3 ng/mL, AUC 49 +/- 10 ng x h/mL. CONCLUSIONS: Tacrolimus appears to have a minimal effect on everolimus blood levels compared with the influence of cyclosporine. The dose of everolimus when combined with tacrolimus needs to be higher than when combined with cyclosporine in order to reach a given everolimus blood level.

Pancytopenia and hepatosplenomegaly in oxalosis.

A 25-year-old woman with oxalosis and end-stage renal disease had pancytopenia and massive hepatosplenomegaly associated with extensive bone marrow deposition of calcium oxalate. A ferrokinetic study suggested profound reduction in erythrocyte production, and peripheral blood smears were compatible with myelophthisis and extramedullary hematopoiesis. Mechanical obliteration of bone marrow by calcium oxalate crystals may lead to pancytopenia and hepatosplenomegaly as late extrarenal complications of oxalosis.

Acute intermittent porphyria: clinicopathologic correlation. Report of a case and review of the literature.

Acute intermittent porphyria (AIP), an autosomal dominant disorder, results from a deficiency of the enzyme hydroxymethylbilane synthase. Despite important advances in the characterization of AIP, the pathophysiology of the neurologic manifestations is not clearly understood. We present a patient with AIP followed for 31 years with multiple episodes of hyponatremia during AIP exacerbations. We discuss the clinicopathologic correlation and possible explanations for the morphologic findings, including discrete hypothalamic changes.

Uric acid nephrolithiasis and acute renal failure secondary to streptozotocin nephrotoxicity.

Uric acid nephrolithiasis developed in a 75-year-old man who had received a large cumulative dose of streptozotocin for treatment of metastatic islet cell carcinoma of the pancreas. Oligoanuric renal failure mediated by massive intraureteral uric acid deposits occurred despite normal serum concentrations of uric acid. This case implicates the uricosuric effects of streptozotocin in the pathogenesis of uric acid nephropathy and suggests that renal uric acid excretion should be monitored routinely in patients receiving large cumulative doses of this drug.

Influence of low-dose cyclosporine on the outcome of treatment with OKT3 for acute renal allograft rejection.

The outcomes of 51 consecutive patients who received OKT3 for acute renal allograft rejection were analyzed. Thirty patients (group 1), previously maintained on cyclosporine, continued to receive 50% of their maintenance dose of CsA during OKT3; 21 patients (group 2) either never received CsA or temporarily discontinued CsA during OKT3. All patients received low doses of azathioprine and prednisone during OKT3. Rejection was reversed by OKT3 in 90% of patients in group 1 and in 62% of patients in group 2. Continuation of CsA during OKT3 did not increase the incidence of serious infections following OKT3. Serum creatinine concentrations in groups 1 and 2 were comparable before, during, and after therapy with OKT3 suggesting that low doses of CsA do not induce graft dysfunction during therapy with the monoclonal antibody. In a subset of 22 prospectively studied patients, anti-OKT3 antibodies developed in 2 of 13 patients (15%) who continued low-dose CsA during OKT3 and in 6 of 9 patients (67%) in whom CsA was temporarily discontinued during OKT3. We conclude that administration of low doses of CsA during therapy with OKT3 may reduce the formation of anti-OKT3 antibodies without compromising reversal of rejection by the monoclonal antibody and without increasing the short-term risk of infection or graft dysfunction.

Renal transplantation using a kidney with a large benign cyst.

We report a case in which a living donor kidney that contained a large benign cyst was successfully transplanted between a mother and her daughter. The donor, a 53-year-old woman, had good renal function, but her right kidney contained a large 4-cm cyst that had a benign appearance on computed tomography. At operation the cyst was proven to be benign by frozen-section histological examination and the transplant was performed. Both donor and recipient continue to enjoy satisfactory renal function 3 years after transplantation. A review of the literature regarding renal cysts and management strategies for use of cystic kidneys in transplantation are presented.

Inhibition of anti-OKT3 antibody generation by cyclosporine--results of a prospective randomized trial.

To investigate the influence of therapy with cyclosporine on the generation of antibodies to OKT3, 51 renal transplant recipients previously maintained on CsA, azathioprine, and prednisone were allocated randomly either to receive 50% of their maintenance dose of CsA (group 1, n = 27) or to discontinue CsA (group 2, n = 24) during treatment with OKT3 for acute renal allograft rejection. In the month following therapy with OKT3, anti-OKT3 antibodies were detected in 11% of patients in group 1 and in 42% of patients in group 2 (P less than 0.02). No patient in group 1 developed antibody titers greater than 1:100, whereas 4 patients in group 2 developed titer greater than or equal to 1:1000. Rejection was reversed in 96% of patients in group 1 and in only 75% of patients in group 2 (P less than 0.03), suggesting that continued administration of reduced doses of CsA during therapy with OKT3 improves the short-term response to this monoclonal antibody. Results of this study suggest that concurrent administration of CsA during therapy with OKT3 inhibits the generation of anti-OKT3 antibodies and improves the response to this monoclonal antibody.

Hypertension after pancreas-kidney transplantation: role of bladder versus enteric pancreatic drainage.

BACKGROUND: Recent reports suggest that hypertension may be less common after simultaneous pancreas-kidney transplantation than after kidney transplantation alone. However, the mechanisms for this beneficial effect have not been delineated. We hypothesize that lower blood pressures may result from chronic volume depletion in patients with bladder-drained pancreatic allografts. METHODS: We compared the incidence and severity of hypertension 12 months after transplantation in 79 bladder-drained pancreas-kidney recipients and 46 diabetic kidney-only recipients. These two groups were compared with a smaller group of enterically drained pancreas-kidney recipients. Blood pressure was also compared before and after surgical conversion from bladder to enteric drainage in 10 patients. RESULTS: Hypertension was significantly less common and less severe after pancreas-kidney transplantation than after kidney transplantation alone, but the benefit of the pancreas transplant was evident only in bladder-drained patients. Logistic regression analysis of the bladder-drained pancreas-kidney patients confirmed the independent impact of the pancreatic allograft on the presence of hypertension, indicated an independent association with serum creatinine concentration and donor age, but suggested no correlation with recipient age, race, or number of rejection episodes. A comparison of blood pressures before and after pancreatic conversion from bladder to enteric drainage indicated no significant change in the prevalence or severity of hypertension. CONCLUSIONS: We conclude that the beneficial effect of a pancreas transplant on the prevalence and severity of hypertension after simultaneous pancreas-kidney transplantation is limited to bladder-drained patients. Although it is possible that the effect is mediated by chronic volume depletion, the observation that blood pressure does not increase after conversion from bladder to enteric drainage suggests that other factors may be involved.

A prospective randomized trial of prednisone versus no prednisone maintenance therapy in cyclosporine-treated and azathioprine-treated renal transplant patients.

The purpose of this study was to evaluate early (6-12 days) prednisone withdrawal in cyclosporine- and azathioprine-treated renal transplant recipients. Patients, including 8 recipients of live-related donor kidneys and 59 recipients of cadaver donor kidneys, were prospectively randomized to receive maintenance prednisone (PRED) therapy or not (NOPRED) in addition to antilymphocyte globulin, cyclosporine, and azathioprine. Rejection episodes were initially treated with methylprednisolone pulses, and OKT3 monoclonal antibody was used to treat steroid resistant rejections that were verified by biopsy. NOPRED patients were declared protocol failures and returned to PRED therapy if they sustained 2 steroid-sensitive rejection episodes in the first 3 months or an OKT3-treated rejection at any time. Patient and graft survival for the LRD patients in both treatment categories were 100% at 12 months. Patient and graft survival for CAD recipients at one year was 94% and 83% (PRED) and 88% and 77% (NOPRED), respectively. Rejection episodes were more frequent (26 of 32 NOPRED patients vs. 19 of 35 PRED patients P = 0.02) and occurred earlier (4.5 weeks in NOPRED vs. 7.7 weeks in PRED patients) in patients not taking maintenance steroids. Rejection severity was also greater in the NOPRED group, as 15 OKT3-treated rejections occurred in that group whereas only 7 OKT3-treated rejections were observed in the PRED group (P = less than 0.01). The incidence of serious infection was similar in each group. Finally, protocol failure occurred in 40% of the LRD patients and 59% of the CAD patients. These data indicate that initiating maintenance therapy without PRED is safe but is attended by a greater risk of developing rejection. Because of this increased incidence and severity of early rejection episodes in NOPRED patients, we do not advise use of this immunosuppressive strategy in renal transplantation.

Effects of steroid withdrawal on posttransplant diabetes mellitus in cyclosporine-treated renal transplant recipients.

Posttransplant diabetes mellitus (PTDM) traditionally has been attributed to therapy with steroids--however, several lines of evidence suggest that cyclosporine also is diabetogenic. A retrospective review revealed that PTDM developed in 9 of 70 previously nondiabetic kidney transplant recipients (12.9%) maintained on prednisone, azathioprine, and CsA compared with 8 of 83 nondiabetics (9.6%) maintained on azathioprine and prednisone alone in an earlier era (P = NS). Among patients maintained on triple-drug therapy, complete withdrawal of prednisone was attempted in 7 renal transplant recipients with PTDM and in 1 recipient of a combined kidney-pancreas transplant who exhibited evidence of type II diabetes mellitus. Seven of the 8 patients were able to discontinue insulin or oral hypoglycemic agents within 4 months of discontinuing steroids. Mean glycohemoglobin level declined from 10.6 +/- 3.6% prior to steroid withdrawal to 6.0 +/- 1.3% within 1 month of steroid cessation, while mean CsA dose and trough CsA blood levels remained unchanged. In 2 patients, mild rejection episodes prompted a return to steroid therapy. Although CsA may be diabetogenic, evidence from this study suggests that withdrawal of steroid therapy is a safe and effective approach to the management of PTDM in patients subsequently maintained on CsA and azathioprine.

The effects of steroid withdrawal on the lipoprotein profiles of cyclosporine-treated kidney and kidney-pancreas transplant recipients.

Lipoprotein profiles were measured before and two months after complete withdrawal of prednisone in 34 kidney and 9 kidney-pancreas transplant recipients subsequently maintained on cyclosporine and azathioprine. Withdrawal of steroid therapy was accompanied by a 17% reduction in total serum cholesterol levels. However, there was a parallel reduction in all other measured lipoprotein concentrations, including an 18% reduction in high-density lipoprotein cholesterol levels. In diabetic recipients of a kidney or kidney-pancreas transplant, the ratio of total to high-density lipoprotein cholesterol was unchanged after steroid withdrawal. In nondiabetic kidney transplant recipients, this ratio actually increased significantly following withdrawal of prednisone. These observations suggest that it is premature to presume that withdrawal of steroid therapy will reduce the cardiovascular risk related to hyperlipidemia in cyclosporine-treated kidney or kidney-pancreas transplant recipients.

Enzyme-linked immunosorbent assay spot detection of interferon-gamma and interleukin 5-producing cells as a predictive marker for renal allograft failure.

BACKGROUND: Despite improvements in the short-term survival of renal transplants, many allografts fail over the 5-10 years after transplantation. We sought to identify an immunologic assay that could identify those patients at high risk for future allograft failure. METHODS: Blood samples were obtained from 23 renal allograft recipients with acute and/or chronic graft dysfunction and from 22 controls. Isolated peripheral blood lymphocytes (PBLs) were tested for interferon (IFN)-gamma and interleukin (IL)-5 production using an enzyme-linked immunosorbent spot assay. IFN-gamma:IL-5 ratios were calculated and compared between groups. Among the 23 patients with graft dysfunction, the ratios were also compared with graft function at 6 months. RESULTS: IFN-gamma:IL-5 ratios of > or = 15 were associated with allograft rejection episodes in 8 of 12 cases, whereas 10 of 11 episodes of graft dysfunction from other causes (infection, drug toxicity, obstruction) were associated with values <15. All normal controls had values <15 (22/22). Among the graft recipients with acute renal failure, all patients with IFN-gamma:IL-5 ratios <15 exhibited improved renal function at 6-month follow-up (14/14), whereas 8 of 9 patients with IFN-gamma:IL-5 ratios > or = 15 developed allograft failure at 6 months (sensitivity 100%, specificity 93.3%). CONCLUSION: In renal transplant recipients with acute allograft dysfunction, mitogen-induced peripheral blood lymphocyte IFN-gamma:IL-5 ratios > or = 15 were highly predictive of allograft failure within 6 months of the assay. This test may be a useful prognostic marker for identification of transplant recipients with acute graft dysfunction who are at high risk for future graft loss and thus allow targeted therapeutic interventions to prolong graft survival.

Inhibition of endothelin-converting enzyme attenuates transplant vasculopathy and rejection in rat cardiac allografts.

BACKGROUND: Transplant vasculopathy in kidney and heart allografts is associated with marked elevation of endothelin-1 (ET-1), but a role for ET-1 in the pathogenesis of transplant vasculopathy and chronic rejection has not been established. We, therefore, tested whether inhibition of ET-1-converting enzyme by phosphoramidon (PA) would attenuate rejection in a rat model of chronic cardiac allograft rejection (Lewis [LEW] to F344). METHODS: Donor LEW rats were pretreated 24 hr before transplantation with a bolus injection of vehicle (water) or PA. Twenty- four hour after transplantation, water or PA was continuously administered through an osmotic mini-pump. Plasma ET-1 levels in Fisher 344 (F344) recipients were 0.8+/-0.1 pg/ml in water-treated rats and 0.2+/-0.2 pg/ml (P<0.01) in PA-treated rats, demonstrating that the PA treatment protocol effectively lowered ET-1 biosynthesis. RESULTS: LEW cardiac allografts treated with water survived (i.e., palpable heart beat) for 16.0+/-0.5 days (n=6). Inhibition of ET-1 secretion by PA improved allograft survival to 28.8+/-3.3 days (P<0.01, n=8). An analysis of cardiac arteries demonstrated that PA treatment attenuated transplant vasculopathy. A morphometric scale of neointima formation (0-5) was 1.4+/-0.2 and 3.6+/-0.2 in PA- or water-treated rats, respectively (P<0.01). The percent of luminal occlusion, as measured by microscopic image analysis, was 19+/-6% in PA-treated animals and 38+/-6% (P<0.01) in animals treated with water. PA treatment also reduced infiltration of ED-1-positive monocytes/macrophages into the vascular neointima. CONCLUSIONS: We conclude that, even in the absence of concomitant immunosuppression, inhibition of ET-1 biosynthesis significantly attenuates transplant vasculopathy and improves survival of LEW to F344 cardiac allografts.

Long-term renal function in type I diabetics after kidney or kidney-pancreas transplantation: influence of number, timing, and treatment of acute rejection episodes.

BACKGROUND: Previous studies comparing renal function in diabetic subjects receiving either a kidney or kidney-pancreas transplant generally have indicated no differences; however, these studies have been limited by inclusion of either a small number of patients or selected patients followed for relatively short periods of time. METHODS: To compare long-term renal function and factors affecting renal function in type I diabetic patients receiving either kidney or kidney-pancreas transplants, the slopes of regression lines generated by plotting the reciprocal of serum creatinine (1/Cr) versus time were measured in 109 consecutive patients followed for at least 12 and up to 102 months after transplantation. Multivariate analyses included linear regression using the slope of 1/Cr versus time as the dependent variable and logistic regression using a positive or negative slope as the dependent variable. RESULTS: Significant differences between kidney-pancreas (n=64) and kidney recipients (n=45) included a smaller proportion of African-Americans, lower rates of HLA matching, lower levels of panel-reactive antibodies, shorter cold ischemia times, a lower incidence of delayed graft function, and a higher incidence of acute renal allograft rejection episodes in the kidney-pancreas group. Trough cyclosporine blood levels were significantly higher in the kidney-pancreas group for the first 12 posttransplant months. The slopes of 1/Cr versus time were negative in each group with a trend toward a more negative slope in the kidney-pancreas group. Multivariate analyses indicated that a concomitant pancreas allograft did not influence long-term renal function. The total number of renal rejection episodes was the best independent predictor of a negative slope of 1/Cr versus time. However, use of OKT3 for the treatment of rejection within the first 3 months of transplantation exerted a surprisingly beneficial effect on long-term renal function, a phenomenon that was most apparent in the kidney-alone group. CONCLUSIONS: The frequency and timing of acute rejection episodes are more important than the influence of a simultaneously transplanted pancreatic allograft in determining long-term function of the transplanted kidney. A concerning trend toward late deterioration of renal function in kidney-pancreas recipients suggests that the benefits of sustained euglycemia, shorter cold ischemia times, lower rates of sensitization, and early use of OKT3 ultimately may be outweighed by the negative effects of more frequent renal rejection episodes.

Withdrawal of steroids after renal transplantation--clinical predictors of outcome.

Withdrawal of steroid therapy in renal transplant recipients is associated with a risk of acute allograft rejection. To define clinical risk factors for rejection associated with steroid withdrawal, we analyzed the clinical characteristics of 107 patients with drawn from steroid therapy at various times after transplantation. Both univariate and multivariate analyses suggested that the timing of steroid withdrawal is an important predictor of steroid withdrawal failure. Withdrawal of steroids was successful in only 13 of 32 patients (41%) in whom prednisone was discontinued shortly after transplantation. In contrast, steroid withdrawal has been successful in 59 of 75 patients (79%) in whom prednisone was discontinued at least 6 months after transplantation. Black race and donor-recipient racial mismatch also were significant predictors of rejection associated with steroid withdrawal. In patients undergoing steroid withdrawal at least 6 months posttransplant, serum creatinine concentration also correlated independently with the risk of rejection. Neither age, sex, HLA match, pretransplant PRA, source of the allograft (cadaver vs. living relative), acute tubular necrosis, nor the presence of diabetes was predictive of the outcome of steroid withdrawal.