Development and evaluation of a composite risk score to predict kidney transplant failure.

BACKGROUND: Although risk factors for kidney transplant failure are well described, prognostic risk scores to estimate risk in prevalent transplant recipients are limited. STUDY DESIGN: Development and validation of risk-prediction instruments. SETTING & PARTICIPANTS: The development data set included 2,763 prevalent patients more than 12 months posttransplant enrolled into the LOTESS (Long Term Efficacy and Safety Surveillance) Study. The validation data set included 731 patients who underwent transplant at a single UK center. PREDICTOR: Estimated glomerular filtration rate (eGFR) and other risk factors were evaluated using Cox regression. OUTCOME: Scores for death-censored and overall transplant failure were based on the summed hazard ratios for baseline predictor variables. Predictive performance was assessed using calibration (Hosmer-Lemeshow statistic), discrimination (C statistic), and clinical reclassification (net reclassification improvement) compared with eGFR alone. RESULTS: In the development data set, 196 patients died and another 225 experienced transplant failure. eGFR, recipient age, race, serum urea and albumin levels, declining eGFR, and prior acute rejection predicted death-censored transplant failure. eGFR, recipient age, sex, serum urea and albumin levels, and declining eGFR predicted overall transplant failure. In the validation data set, 44 patients died and another 101 experienced transplant failure. The weighted scores comprising these variables showed adequate discrimination and calibration for death-censored (C statistic, 0.83; 95% CI, 0.75-0.91; Hosmer-Lemeshow χ(2)P = 0.8) and overall (C statistic, 0.70; 95% CI, 0.64-0.77; Hosmer-Lemeshow χ(2)P = 0.5) transplant failure. However, the scores failed to reclassify risk compared with eGFR alone (net reclassification improvements of 7.6% [95% CI, -0.2 to 13.4; P = 0.09] and 4.3% [95% CI, -2.7 to 11.8; P = 0.3] for death-censored and overall transplant failure, respectively). LIMITATIONS: Retrospective analysis of predominantly cyclosporine-treated patients; limited study size and categorization of variables may limit power to detect effect. CONCLUSIONS: Although the scores performed well regarding discrimination and calibration, clinically relevant risk reclassification over eGFR alone was not evident, emphasizing the stringent requirements for such scores. Further studies are required to develop and refine this process.

Association of caveolin-1 gene polymorphism with kidney transplant fibrosis and allograft failure.

CONTEXT: Caveolin-1 (CAV1) is an inhibitor of tissue fibrosis. OBJECTIVE: To study the association of CAV1 gene variation with kidney transplant outcome, using kidney transplantation as a model of accelerated fibrosis. DESIGN, SETTING, AND PATIENTS: Candidate gene association and validation study. Genomic DNA from 785 white kidney transplant donors and their respective recipients (transplantations in Birmingham, England, between 1996 and 2006; median follow-up, 81 months) were analyzed for common variation in CAV1 using a single-nucleotide polymorphism (SNP) tagging approach. Validation of positive findings was sought in an independent kidney transplant donor-recipient cohort (transplantations in Belfast, Northern Ireland, between 1986 and 2005; n = 697; median follow-up, 69 months). Association between genotype and allograft failure was initially assessed by Kaplan-Meier analysis, then in an adjusted Cox model. MAIN OUTCOME MEASURE: Death-censored allograft failure, defined as a return to dialysis or retransplantation. RESULTS: The presence of donor AA genotype for the CAV1 rs4730751 SNP was associated with increased risk of allograft failure in the Birmingham group (donor AA vs non-AA genotype in adjusted Cox model, hazard ratio [HR], 1.97; 95% confidence interval [CI], 1.29-3.16; P = .002). No other tag SNPs showed a significant association. This finding was validated in the Belfast cohort (in adjusted Cox model, HR, 1.56; 95% CI, 1.07-2.27; P = .02). Overall graft failure rates were as follows: for the Birmingham cohort, donor genotype AA, 22 of 57 (38.6%); genotype CC, 96 of 431 (22.3%); and genotype AC, 66 of 297 (22.2%); and for the Belfast cohort, donor genotype AA, 32 of 48 (67%); genotype CC, 150 of 358 (42%); and genotype AC, 119 of 273 (44%). CONCLUSION: Among kidney transplant donors, the CAV1 rs4730751 SNP was significantly associated with allograft failure in 2 independent cohorts.

Increased incidence of infections following the late introduction of mycophenolate mofetil in renal transplant recipients.

BACKGROUND: Late introduction of mycophenolate mofetil (MMF) is used in renal transplant patients to allow calcineurin inhibitor (CNI) withdrawal. This change in treatment may alter the immunosuppressive load predisposing patients to infections. To assess this we have analysed infection rates in 30 consecutive patients with chronic allograft nephropathy commenced on MMF for CNI withdrawal. Methods and results. The study period was from 12 months pre-commencement to 12 months post-commencement. At commencement, patient mean age was 51.2 +/- 12.9 years and mean time post-transplant was 3170 +/- 2130 days. Estimated glomerular filtration rate (eGFR) at the start of the study period and at conversion was 30.7 +/- 12.1 ml/min and 23.1 +/- 9.9 ml/min, respectively. The mean dose of MMF post-conversion was 1575 +/- 428 mg/day. Estimated GFR had stabilized at 12 months post-conversion to 25.3 +/- 12.2 ml/min. There was a significant increase in infections following conversion: pre-conversion, 26.7% (8/30); post-conversion, 66.6% (20/30) (chi(2) = 24.5, P < 0.0005). There was an inverse correlation between eGFR at conversion and infection rates post-conversion (r = -0.379, P = 0.039). There were no hospitalizations for infection pre-conversion and 6 patients (20%) were hospitalized post-conversion, for a total of 285 days (7-107). CONCLUSION: There is significant morbidity associated with an increased incidence of infection after late introduction of MMF at standard doses in renal transplant recipients. This risk may be related to GFR at the time of conversion.

Chronic kidney disease after nonrenal solid organ transplantation: a histological assessment and utility of chronic allograft damage index scoring.

BACKGROUND: It is proposed that chronic calcineurin inhibitor (CNI) nephrotoxicity has a central role in chronic kidney disease after nonrenal solid organ transplantation (NRSOT), although there are little data on renal histology in this setting. The aim of this study was to assess the histological features and renal outcomes of a cohort of patients with chronic kidney disease after NRSOT. METHODS: Renal biopsies of 62 NRSOT recipients were evaluated for histological diagnoses. Biopsies were graded for chronic allograft damage index parameters and for arteriolar hyalinosis. The sum of all chronic allograft damage index parameters and arteriolar hyalinosis scores was called chronic damage index. RESULTS: The biopsies were performed at a median of 4 (range: 0.3-15.9) years after NRSOT and at serum creatinine of 318±17.7 µmol/L (mean±standard deviation). Twenty-two (35.5%) biopsies showed predominant features of chronic CNI nephrotoxicity, 27 (43.5%) predominant features of hypertensive nephropathy, and 12 (19.3%) an alternative primary renal pathology. Twenty-four (38.7%) patients had progression to end-stage renal disease, at a median of 1.5 (0-10.1) years after biopsy and 6.9 (0.3-19.2) years after NRSOT. The risk of renal progression was associated with in situ damage measured by chronic damage index. CONCLUSIONS: Although CNI nephrotoxicity is an important cause of renal failure after NRSOT, many patients do not have overt histological evidence of CNI toxicity. Quantitative parameters of chronic damage can stratify renal prognosis.

T Lymphocyte responses to nonpolymorphic HLA-derived peptides are associated with chronic renal allograft dysfunction.

BACKGROUND: The routine assessment of cellular alloimmunity to guide therapy is of perennial interest because this limb of the immune system is the main target of current transplant immunosuppression. That this has not as yet been realized in clinical practice reflects the difficulty of developing a standardized assay that accounts for the high degree of polymorphism exhibited by histocompatibility antigens. METHODS: We have investigated whether immune responses to peptides derived from nonpolymorphic regions of human leukocyte antigen arise after transplantation, in particular in those with chronic allograft dysfunction. RESULTS: Peripheral blood mononuclear cell γ-interferon production to peptides derived from the nonpolymorphic α3 domain of class 1 human leukocyte antigen occurred more frequently in long-term renal transplant recipients than healthy controls (51/110 vs. 1/18, 46.3% vs. 5.5%; P<0.001). These responses were associated with chronic allograft dysfunction manifested by a reduced and decreasing estimated glomerular filtration rate (responders vs. nonresponders: 39.5 vs. 48.8 mL/min, P=0.015 and -4.1 vs. -1.3 mL/min/year, P=0.008). Responses occurred mostly to autologous, "cryptic self-epitopes" and arose from CD4CD25CD127 T lymphocytes, which have been previously implicated in chronic rejection. CONCLUSION: These findings suggest a strategy for assessing cellular immune responses to transplantation antigens with potential for generalization.

Chronic graft versus host disease is associated with an immune response to autologous human leukocyte antigen-derived peptides.

BACKGROUND: Chronic graft-versus-host disease (cGVHD) is a major complication of allogeneic bone marrow transplantation (BMT) the immunopathogenesis of which is not well understood. Humoral and cellular immunity are both implicated, patients express a range of autoantibodies, but the targets of cellular immunity are not well defined. Autologous human leukocyte antigen (HLA)-derived peptides constitute a significant proportion of the repertoire. METHODS: We have investigated the response to HLA-derived peptides after allogeneic BMT using gamma-interferon enzyme-linked immunospot assay (ELISPOT). We also studied the release of this gamma-interferon by flow cytometry in a subgroup of responsive patients. RESULTS: The peripheral blood mononuclear cell response was assessed by gamma-interferon ELISPOT in 42 BMT recipients (21 with cGVHD) and 30 healthy donors. Thirteen of 21 patients diagnosed with cGVHD responded to at least one HLA-derived peptide compared with 1 of 21 patients without cGVHD (62% vs. 5%, P<10) and 1 of 30 healthy donors. In all but one patient these peptides correspond with the sequences of autologous HLA. The median single peptide-specific response in ELISPOT was 43/10 peripheral blood mononuclear cells. In a subgroup studied by flow cytometry, gamma-interferon production to individual peptides occurred in 0.04% to 0.18% of CD4 T lymphocytes. CONCLUSION: These observations identify HLA-derived peptides as targets of a cellular immune response in cGVHD.

Calciphylaxis following kidney transplantation: a case report.

INTRODUCTION: Calciphylaxis occurring after kidney transplantation is rare and rarely reported. It results in chronic non-healing wounds and is associated with a poor prognosis and is often fatal. We present a case of proximal lower limb calciphylaxis that occurred early after kidney transplantation. The patient had no classic associated risk factors. He had previously had a total parathyroidectomy but had normal serum calcium-phosphate product and parathyroid hormone levels. The clinical outcome of this case was favorable and highlights some fundamental issues relating to management. CASE PRESENTATION: A 70-year-old British Caucasian man with end-stage renal failure secondary to IgA nephropathy presented six months post kidney transplantation with cutaneous calciphylaxis lesions involving the medial aspect of the thigh bilaterally. CONCLUSION: To the best of our knowledge, this is the first reported case of rapid onset cutaneous calciphylaxis occurring soon after kidney transplantation that was associated with a favorable outcome. Cutaneous calciphylaxis lesions should be promptly managed with meticulous wound care, antimicrobial therapy and the correction of calcium-phosphate product where indicated.

Aspergillus aortitis: a cause for aortic perforation in a patient following combined aortic valve surgery and liver transplantation.

We report a case of aspergillus fumigatus aortitis in a patient following combined aortic valve replacement and orthotopic liver transplantation for significant aortic stenosis and alcoholic liver cirrhosis. At operation, a suspicious excavating lesion was found on the native aortic valve and specimen sent for culture. The ascending aorta and aortic sinuses were found to be normal. Routine immunosuppression was commenced post transplant. Urgent valve microscopy was highly suspicious of fungal growth, and antifungal therapy was instituted. Day 18 post-surgery the patient unexpectedly arrested. Post mortem findings showed ascending aortic perforation with multiple fungal lesions noted. Microscopy demonstrated aspergillus fumigatus invading the aortic wall. This is the first case report illustrating a dormant phase of aspergillus fumigatus endocarditis that was activated following surgery and immunosuppression leading to aortitis and subsequent perforation.