Association of CYP3A variants with kidney transplant outcomes.

Cyclosporine is used extensively in kidney transplantation and is a substrate for cytochrome P450 enzymes. The role of cytochrome p450 polymorphisms in kidney transplant outcome has not yet been fully elucidated. We investigate the clinical impact of single nucleotide polymorphisms in CYP3A4, CYP3A5, PPARα, and POR*28 in 255 kidney transplant recipients. We examine for any association with graft survival, time to first cancer, and delayed graft function, and also measure cyclosporine levels at days 3, 10, and months 1, 3, 6, and 12 after transplantation. The CYP3A4*22 allele is significant associated with the development of cancer post-kidney transplantation (HR 0.20, 95% CI 0.07-0.57, p = 0.003). It is not significantly associated with graft survival. No other SNP's were associated with graft survival time to first cancer, or delayed graft function. There was a non-significant trend of lower cyclosporine dose requirement in CYP3A4*22 carriers. Independent replication of our findings is now warranted to confirm or reject the role of CYP3A variants in cancer development following kidney transplantation.

Factors affecting eGFR 5-year post-deceased donor renal transplant: analysis and predictive model.

AIM: Long-term survival of renal allografts has improved over the last 20 years. However, less is known about current expectations for long-term allograft function as determined by estimated glomerular filtration rate (eGFR). The aim of this study was to investigate factors which affect graft function at 5 years' post-renal transplantation. The statistically significant factors were then used to construct a predictive model for expected eGFR at five years' post-transplant. METHODS: We retrospectively reviewed all adult patients who received a renal transplant in the Republic of Ireland between 1990 and 2004. Data collected included era of transplantation (1990-1994, 1995-1999, 2000-2004), donor and recipient age and gender, number of human leucocyte antigen mismatches, cold ischemia time (CIT), number of prior renal transplants, immunosuppressive regimen used and acute rejection episodes. Estimated GFR was calculated at 5 years after transplantation from patient data using the Modified Diet in Renal Disease (MDRD) equation. Consecutive sampling was used to divide the study population into two equal unbiased groups of 489 patients. The first group (derivation cohort) was used to construct a predictive model for eGFR five years' post-transplantation, the second (validation cohort) to test this model. RESULTS: Nine hundred and seventy eight patients were analyzed. The median age at transplantation was 43 years (range 18-78) and 620 (63.4%) were male. One hundred and seventy five patients (17.9%) had received a prior renal transplant. Improved eGFR at five years' post-transplantation was associated with tacrolimus-based combination immunosuppression, younger donor age, male recipient, absence of cytomegalovirus disease and absence of acute rejection episodes as independently significant factors (p < 0.05). The predictive model developed using these factors showed good correlation between predicted and actual median eGFR at five years. The model explained 20% of eGFR variability. The validation model findings were consistent with the derivation model (21% variability of eGFR explained by model using same covariates on new data). CONCLUSION: The predictive model we have developed shows good correlation between predicted and actual median eGFR at five years' post-transplant. Applications of this model include comparison of current and future therapy options such as new immunosuppressive regimens.

A genome-wide association study of recipient genotype and medium-term kidney allograft function.

BACKGROUND: We examined, through genome-wide association studies (GWAS), the correlation between recipient genetic variation and renal function at five yr. METHODS: Our cohort contained 326 Irish, first time, kidney-only, deceased donor, transplant recipients on calcineurin inhibitors (263 had a functioning graft at five yr) between 1993 and 2002. Outcomes were creatinine at five yr and long-term graft function. RESULTS: Two variants were identified showing borderline genome-wide significance - one on chromosome 18 (p = 4.048e-08, rs6565887) and another on chromosome 14 (p = 7.631e-08, rs3811321). Individually, the two SNPs explained up to 8.8% and 11.29% of five-yr creatinine variance, respectively, while together they explained up to 17.4% of trait variance. Both variants were predictors of long-term allograft function (p = 0.004, 70% vs 30% survival at 10 yr). The chromosome 14 variant is located in the intergenic region of the T-Cell Receptor Alpha locus. CONCLUSIONS: Using a genome-wide approach, we have identified two associations with five-yr creatinine levels in renal transplant recipients treated with calcineurin inhibitors. Independent replication is now warranted to clarify the clinical significance of these results.

Clinical and pathologic characteristics of hereditary apolipoprotein A-I amyloidosis in Ireland.

AIM: Apolipoprotein A-I amyloidosis is a rare, autosomal dominant disorder characterized by progressive accumulation of amyloid fibrils in tissues, leading to renal and hepatic disease. We describe the clinical manifestations and pathologic features of kidney disease in three Irish families. METHODS: This observational study examines all known cases of chronic kidney disease due to hereditary apolipoprotein A-I amyloidosis in Ireland. Patients were identified by physician interview. In all of the affected individuals the disease was caused by the Gly26Arg heterozygous mutation. Immunohistochemistry confirmed that amyloid deposits were composed of apolipoprotein A-I fibrils. Family trees and clinical data were obtained via analysis of patient medical records. RESULTS: The vast majority of affected cases had demonstrable kidney disease, with variable liver disease. Renal disease most commonly manifested as slowly progressive renal impairment with mild proteinuria. In one kindred, a severe, debilitating peripheral neuropathy was common among affected family members. Histology demonstrated tubulointerstitial fibrosis with amyloid deposition in the medulla. There was very high penetrance within affected families. Of five patients who were transplanted, one transplant was lost after 5 years due to recurrent disease. One patient died from sepsis shortly after transplant. CONCLUSION: Hereditary apolipoprotein A-I amyloidosis is characterized by slowly progressive renal disease. Amyloid is deposited in the renal medulla highlighting the need to examine the medulla on renal biopsy. Overall, kidney transplantation conferred a survival advantage.

Concordance of outcomes of pairs of kidneys transplanted into different recipients.

Kidney transplant outcomes are influenced by donor characteristics, including age and gender. Additional donor factors, both genetic and environmental, also influence graft outcome. We aim to assess the strength of donor factors in determining kidney transplant outcomes by comparing paired kidneys from a single donor transplanted into different recipients. We conducted a retrospective cohort study of outcomes of pairs of deceased donor kidneys transplanted in our centre between 1992 and 2008. We examined the relationship within pairs for eGFR at 1 year and at 5 years post-transplant using Spearman's Correlation and the concordance of pairs of transplant kidneys with respect to the occurrence of acute rejection and delayed graft function (DGF). A total of 652 recipient pairs were analysed. Spearman's correlation for eGFR was 0.36 at 1 year and 0.36 at 5 years post-transplant. The incidence of DGF was 11%. The odds ratio of DGF occurring if the contralateral kidney had DGF was 5.99 (95% CI, 3.19-11.25). There is a significant degree of relationship within pairs of kidneys transplanted from the same donor for serum creatinine at 1 year and 5 years post-transplant and also for the occurrence of delayed graft function.

Painful skin lesion in a patient on haemodialysis: a diagnosis not to miss.

An 81-year-old man was admitted under the care of a plastic surgery team with a 10-day history of a painful left lower leg skin lesion after a punch biopsy of a naevus. His background history includes end-stage kidney disease secondary to hypertensive nephropathy, on intermittent haemodialysis via fistula. Other significant background history includes stroke, hypertension and ischaemic heart disease with coronary artery stents. There was no history of warfarin use. He was initially treated with a 5-day course of oral antibiotics with no improvement. He was referred to the hospital where he was admitted under the plastic surgery team who had completed the punch biopsy for intravenous antibiotics for presumed cellulitis. During his admission, the nephrology service were consulted to prescribe routine inpatient haemodialysis. Further history taking and wound review identified a 10-day history of an extremely painful skin lesion with an eschar and surrounding dusky, purpuric skin. Given the disproportionate pain and black eschar which are not in keeping with cellulitis, a diagnosis of calciphylaxis was made. He was commenced sodium thiosulfate on haemodialysis.

Posttransplant Lymphoproliferative Disorders in Irish Renal Transplant Recipients: Insights From a National Observational Study.

BACKGROUND: Posttransplant lymphoproliferative disorders (PTLD) are a common malignancy after renal transplantation with a high incidence of PTLD described in the first posttransplant year. We sought to determine incidence and risk determinants of PTLD in Irish kidney transplant recipients. METHODS: Retrospective observational study of 1996 adult first kidney transplant recipients between 1991 and 2010 in the Republic of Ireland. Recipients were cross-referenced with the National Cancer Registry to determine incidence of PTLD. Kaplan-Meier analysis was performed for PTLD-free survival, allograft survival, and patient survival after PTLD. Cox proportional hazards models were used to identify independent risk factors for PTLD in our population. RESULTS: We identified 31 cases of PTLD during the study period. Histological subgroups included: early lesions (n = 1); polymorphic PTLD (n = 1); monomorphic PTLD (n = 27), Hodgkin disease (n = 2). Median time to PTLD diagnosis was 8.3 (range, 1.2-13.9) years. Cumulative incidence (95% CI) of PTLD at 1, 2, 3, 5, 10, and 15 years was 0%, 0.16% (0.05-0.5%), 0.21% (0.08-0.57%), 0.21% (0.08-0.57%), 1.76% (1.15-2.69%), and 3.07% (2.1-4.43%), respectively. Allograft survival after PTLD diagnosis was 94.4% (66.6-99.2%) at 5 years. Patient survival after PTLD diagnosis was 64% at 1 year, 53% at 2 years, 48% at 5 years, and 37% at 10 years. No risk factors for PTLD were identified. CONCLUSIONS: We found a paucity of early onset PTLD in our cohort with no cases in the first posttransplant year. Potential contributing factors included a high prevalence of previous Epstein-Barr virus exposure and a relatively low immunological risk profile in our recipient cohort compared with prior studies. Further studies are required to reevaluate the epidemiology of PTLD in the modern era of transplant immunosuppression.

Urinary biomarkers of chronic allograft nephropathy.

PURPOSE: Chronic allograft nephropathy (CAN) is widely accepted as the leading cause of renal allograft loss after the first year post transplantation. This study aimed to identify urinary biomarkers that could predict CAN in transplant patients. EXPERIMENTAL DESIGN: The study included 34 renal transplant patients with histologically proven CAN and 36 renal transplant patients with normal renal function. OrbiTrap MS was utilized to analysis a urinary fraction in order to identify other members of a previously identified biomarker tree . This novel biomarker pattern offers the potential to distinguish between transplant recipients with CAN and those with normal renal function. RESULTS: The primary node of the biomarker pattern was reconfirmed as ß2 microglobulin. Three other members of this biomarker pattern were identified: neutrophil gelatinase-associated lipocalin, clusterin, and kidney injury biomarker 1. Significantly higher urinary concentrations of these proteins were found in patients with CAN compared to those with normal kidney function. CONCLUSIONS AND CLINICAL RELEVANCE: While further validation in a larger more-diverse patient population is required to determine if this biomarker pattern provides a potential means of diagnosing CAN by noninvasive methods in a clinical setting, this study clearly demonstrates the biomarkers' ability to stratify patients based on transplant function.

Surveillance of nonmelanoma skin cancer incidence rates in kidney transplant recipients in Ireland.

BACKGROUND: The incidence of nonmelanomatous skin cancer (NMSC) is substantially higher among renal transplant recipients (RTRs) than in the general population. With a growing RTR population, a robust method for monitoring skin cancer rates in this population is required. METHODS: A modeling approach was used to estimate the trends in NMSC rates that adjusted for changes in the RTR population (sex and age), calendar time, the duration of posttransplant follow-up, and background population NMSC incidence rates. RTR databases in both Northern Ireland (NI) and the Republic of Ireland (ROI) were linked to their respective cancer registries for diagnosis of NMSC, mainly squamous cell carcinoma (SCC) and basal cell carcinoma (BCC). RESULTS: RTRs in the ROI had three times the incidence (P<0.001) of NMSC compared with NI. There was a decline (P<0.001) in NMSC 10-year cumulative incidence rate in RTRs over the period 1994-2009, which was driven by reductions in both SCC and BCC incidence rates. Nevertheless, there was an increase in the incidence of NMSC with time since transplantation. The observed graft survival was higher in ROI than NI (P<0.05) from 1994-2004. The overall patient survival of RTRs was similar in NI and ROI. CONCLUSION: Appropriate modeling of incidence trends in NMSC among RTRs is a valuable surveillance exercise for assessing the impact of change in clinical practices over time on the incidence rates of skin cancer in RTRs. It can form the basis of further research into unexplained regional variations in NMSC incidence.

C3 glomerulopathy: clinicopathologic features and predictors of outcome.

BACKGROUND AND OBJECTIVES: The term C3 glomerulopathy describes renal disorders characterized by the presence of glomerular deposits composed of C3 in the absence of significant amounts of Ig. On the basis of electron microscopy appearance, subsets of C3 glomerulopathy include dense deposit disease (DDD) and C3 glomerulonephritis (C3GN). The full spectrum of histologic change observed in C3 glomerulopathy has yet to be defined and pathologic predictors of renal outcome within this patient population remain largely unknown. This study thus characterized a large C3 glomerulopathy cohort and identified clinicopathologic predictors of renal outcome. DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS: All patients with kidney biopsies fulfilling criteria for C3 glomerulopathy from two quaternary renal centers within the United Kingdom and Ireland between 1992 and 2012 were retrospectively reviewed. We recorded histologic, demographic, and clinical data and determined predictors of ESRD using the Cox proportional hazards model. RESULTS: Eighty patients with C3 glomerulopathy were identified: 21 with DDD and 59 with C3GN. Patients with DDD were younger, more likely to have low serum C3 levels, and more likely to have crescentic GN than patients with C3GN. Patients with C3GN were older and had more severe arteriolar sclerosis, glomerular sclerosis, and interstitial scarring than patients with DDD. Of 70 patients with available follow-up data, 20 (29%) progressed to ESRD after a median of 28 months. Age >16 years, DDD subtype, and crescentic GN were independent predictors of ESRD within the entire cohort. Renal impairment at presentation predicted ESRD only among patients with DDD. CONCLUSIONS: Although detailed serologic and genetic data are lacking, this study nevertheless identifies important clinicopathologic distinctions between patients with DDD and C3GN. These include independent predictors of renal outcome. If replicated in other cohorts, these predictors could be used to stratify patients, enabling application of emerging mechanism-based therapies to patients at high risk for poor renal outcome.

Transplant outcomes in patients with idiopathic membranous nephropathy.

Background. The natural history of idiopathic membranous nephropathy and recurrent disease in transplants is variable. We performed a retrospective cohort study of renal transplant recipients with a primary diagnosis of idiopathic membranous nephropathy. We aimed to establish patterns of disease recurrence and to identify factors associated with disease recurrence. Methods. We accessed the Irish renal transplant database to identify patients with biopsy-proven idiopathic membranous nephropathy in receipt of a renal transplant between 1982 and 2010. A detailed medical chart review was performed in all cases, and a senior renal histopathologist reviewed all histology specimens. Results. The outcomes of 32 patients, in receipt of 36 grafts, are reported. There was a male preponderance (n = 29). Significant graft dysfunction, directly attributable to recurrent disease, was evident in 31% of cases at 10 years. There was no significant association between time on dialysis, HLA mismatch, occurrence of rejection, and the development of recurrent membranous disease. One patient was retransplanted twice; all three grafts were lost to aggressive recurrent membranous disease. Conclusions. It remains difficult to identify those that will develop recurrent membranous nephropathy. Almost one third of patients in this cohort developed clinically significant recurrent disease at 10 years.

Recurrence of anti-neutrophil cytoplasmic antibody-associated vasculitis in appropriately immunosuppressed renal transplant patients: a discussion of two cases.

BACKGROUND: Granulomatosis with polyangiitis (GPA) (formerly known as Wegener's granulomatosis) is a multisystem autoimmune disease of unknown aetiology. Renal disease manifests as a crescentic glomerulonephritis, with varying degrees of renal failure. Ten percent of patients progress to end-stage kidney disease. Relapse of GPA in renal transplant patients is rare, with a rate of 0.09 relapses per patient per year. PATIENTS AND METHODS: We describe two cases of GPA relapse in immunosuppressed renal transplant patients. RESULTS: These patients presented with new-onset graft disfunction, having previously had an uncomplicated posttransplant course. Both patients were on appropriate doses of immunosuppressive agents at the time of relapse, with therapeutic target levels of tacrolimus. We describe the background history and management of both patients. CONCLUSION: The cases described inform us that although recurrence of anti-neutrophil cytoplasmic antibody vasculitis in transplant patients is rare, it should remain on our list of differential diagnoses in allograft disfunction.