Ellipro scores of donor epitope specific HLA antibodies are not associated with kidney graft survival.

In kidney transplantation, donor HLA antibodies are a risk factor for graft loss. Accessibility of donor eplets for HLA antibodies is predicted by the ElliPro score. The clinical usefulness of those scores in relation to transplant outcome is unknown. In a large Dutch kidney transplant cohort, Ellipro scores of pretransplant donor antibodies that can be assigned to known eplets (donor epitope specific HLA antibodies [DESAs]) were compared between early graft failure and long surviving deceased donor transplants. We did not observe a significant Ellipro score difference between the two cohorts, nor significant differences in graft survival between transplants with DESAs having high versus low total Ellipro scores. We conclude that Ellipro scores cannot be used to identify DESAs associated with early versus late kidney graft loss in deceased donor transplants.

Determination of the clinical relevance of donor epitope-specific HLA-antibodies in kidney transplantation.

In kidney transplantation, survival rates are still partly impaired due to the deleterious effects of donor specific HLA antibodies (DSA). However, not all luminex-defined DSA appear to be clinically relevant. Further analysis of DSA recognizing polymorphic amino acid configurations, called eplets or functional epitopes, might improve the discrimination between clinically relevant vs. irrelevant HLA antibodies. To evaluate which donor epitope-specific HLA antibodies (DESAs) are clinically important in kidney graft survival, relevant and irrelevant DESAs were discerned in a Dutch cohort of 4690 patients using Kaplan-Meier analysis and tested in a cox proportional hazard (CPH) model including nonimmunological variables. Pre-transplant DESAs were detected in 439 patients (9.4%). The presence of certain clinically relevant DESAs was significantly associated with increased risk on graft loss in deceased donor transplantations (p < 0.0001). The antibodies recognized six epitopes of HLA Class I, 3 of HLA-DR, and 1 of HLA-DQ, and most antibodies were directed to HLA-B (47%). Fifty-three patients (69.7%) had DESA against one donor epitope (range 1-5). Long-term graft survival rate in patients with clinically relevant DESA was 32%, rendering DESA a superior parameter to classical DSA (60%). In the CPH model, the hazard ratio (95% CI) of clinically relevant DESAs was 2.45 (1.84-3.25) in deceased donation, and 2.22 (1.25-3.95) in living donation. In conclusion, the developed model shows the deleterious effect of clinically relevant DESAs on graft outcome which outperformed traditional DSA-based risk analysis on antigen level.

T-Cell Epitopes Shared Between Immunizing HLA and Donor HLA Associate With Graft Failure After Kidney Transplantation.

CD4+ T-helper cells play an important role in alloimmune reactions following transplantation by stimulating humoral as well as cellular responses, which might lead to failure of the allograft. CD4+ memory T-helper cells from a previous immunizing event can potentially be reactivated by exposure to HLA mismatches that share T-cell epitopes with the initial immunizing HLA. Consequently, reactivity of CD4+ memory T-helper cells toward T-cell epitopes that are shared between immunizing HLA and donor HLA could increase the risk of alloimmunity following transplantation, thus affecting transplant outcome. In this study, the amount of T-cell epitopes shared between immunizing and donor HLA was used as a surrogate marker to evaluate the effect of donor-reactive CD4+ memory T-helper cells on the 10-year risk of death-censored kidney graft failure in 190 donor/recipient combinations using the PIRCHE-II algorithm. The T-cell epitopes of the initial theoretical immunizing HLA and the donor HLA were estimated and the number of shared PIRCHE-II epitopes was calculated. We show that the natural logarithm-transformed PIRCHE-II overlap score, or Shared T-cell EPitopes (STEP) score, significantly associates with the 10-year risk of death-censored kidney graft failure, suggesting that the presence of pre-transplant donor-reactive CD4+ memory T-helper cells might be a strong indicator for the risk of graft failure following kidney transplantation.

Antibodies against ARHGDIB are associated with long-term kidney graft loss.

The clinical significance of non-HLA antibodies on renal allograft survival is a matter of debate, due to differences in reported results and lack of large-scale studies incorporating analysis of multiple non-HLA antibodies simultaneously. We developed a multiplex non-HLA antibody assay against 14 proteins highly expressed in the kidney. In this study, the presence of pretransplant non-HLA antibodies was correlated to renal allograft survival in a nationwide cohort of 4770 recipients transplanted between 1995 and 2006. Autoantibodies against Rho GDP-dissociation inhibitor 2 (ARHGDIB) were significantly associated with graft loss in recipients transplanted with a deceased-donor kidney (N = 3276) but not in recipients of a living-donor kidney (N = 1496). At 10 years after deceased-donor transplantation, recipients with anti-ARHGDIB antibodies (94/3276 = 2.9%) had a 13% lower death-censored covariate-adjusted graft survival compared to the anti-ARHGDIB-negative (3182/3276 = 97.1%) population (hazard ratio 1.82; 95% confidence interval, 1.32-2.53; P = .0003). These antibodies occur independently from donor-specific anti-HLA antibodies (DSA) or other non-HLA antibodies investigated. No significant relations with graft loss were found for the other 13 non-HLA antibodies. We suggest that pretransplant risk assessment can be improved by measuring anti-ARHGDIB antibodies in all patients awaiting deceased-donor transplantation.

Allocation to highly sensitized patients based on acceptable mismatches results in low rejection rates comparable to nonsensitized patients.

Whereas regular allocation avoids unacceptable mismatches on the donor organ, allocation to highly sensitized patients within the Eurotransplant Acceptable Mismatch (AM) program is based on the patient's HLA phenotype plus acceptable antigens. These are HLA antigens to which the patient never made antibodies, as determined by extensive laboratory testing. AM patients have superior long-term graft survival compared with highly sensitized patients in regular allocation. Here, we questioned whether the AM program also results in lower rejection rates. From the PROCARE cohort, consisting of all Dutch kidney transplants in 1995-2005, we selected deceased donor single transplants with a minimum of 1 HLA mismatch and determined the cumulative 6-month rejection incidence for patients in AM or regular allocation. Additionally, we determined the effect of minimal matching criteria of 1 HLA-B plus 1 HLA-DR, or 2 HLA-DR antigens on rejection incidence. AM patients showed significantly lower rejection rates than highly immunized patients in regular allocation, comparable to nonsensitized patients, independent of other risk factors for rejection. In contrast to highly sensitized patients in regular allocation, minimal matching criteria did not affect rejection rates in AM patients. Allocation based on acceptable antigens leads to relatively low-risk transplants for highly sensitized patients with rejection rates similar to those of nonimmunized individuals.

Toward a Sensible Single-antigen Bead Cutoff Based on Kidney Graft Survival.

BACKGROUND: There is no consensus in the literature on the interpretation of single-antigen bead positive for a specific HLA antibody. METHODS: To inform the debate, we studied the relationship between various single-antigen bead positivity algorithms and the impact of resulting donor-specific HLA antibody (DSA) positivity on long-term kidney graft survival in 3237 deceased-donor transplants. RESULTS: First, we showed that the interassay variability can be greatly reduced when working with signal-to-background ratios instead of absolute median fluorescence intensities (MFIs). Next, we determined pretransplant DSA using various MFI cutoffs, signal-to-background ratios, and combinations thereof. The impact of the various cutoffs was studied by comparing the graft survival between the DSA-positive and DSA-negative groups. We did not observe a strong impact of various cutoff levels on 10-year graft survival. A stronger relationship between the cutoff level and 1-year graft survival for DSA-positive transplants was found when using signal-to-background ratios, most pronounced for the bead of the same HLA locus with lowest MFI taken as background. CONCLUSIONS: With respect to pretransplant risk stratification, we propose a signal-to-background ratio-6 (using the bead of the same HLA-locus with lowest MFI as background) cutoff of 15 combined with an MFI cutoff of 500, resulting in 8% and 21% lower 1- and 10-year graft survivals, respectively, for 8% DSA-positive transplants.

Psychosocial consequences of living kidney donation: a prospective multicentre study on health-related quality of life, donor-recipient relationships and regret.

BACKGROUND: Previous studies have indicated decreased health-related quality of life (HRQoL) shortly after kidney donation, returning to baseline in the longer term. However, a subgroup of donors experiences persistent HRQoL problems. To identify which HRQoL aspects are impacted most by the donation and to identify at-risk donors, more specific insight into psychosocial donation consequences is needed. METHODS: The current study examined the HRQoL course, donor-perceived consequences of donation for donors, recipients and donor-recipient relationships, and regret up to 12 months post-donation in donors from seven Dutch transplantation centres. Kidney donor candidates (n = 588) completed self-report questionnaires early in the screening procedure, of which 361 (61%) donated their kidney. RESULTS: Data for 230 donors (64%) with complete assessments before donation and 6 and 12 months post-donation were analysed. Results indicated that donor physical HRQoL was comparable at all time points, except for an increase in fatigue that lasted up to 12 months post-donation. Mental HRQoL decreased at 6 months post-donation, but returned to baseline at 12 months. Donors reported large improvements in recipient's functioning and a smaller influence of the recipient's kidney disease or transplantation on the donor's life over time. A subgroup experienced negative donation consequences with 14% experiencing regret 12 months post-donation. Predictors of regret were more negative health perceptions and worse social functioning 6 months post-donation. The strongest baseline predictors of higher fatigue levels after donation were more pre-donation fatigue, worse general physical functioning and a younger age. CONCLUSIONS: Future research should examine predictors of HRQoL after donation to improve screening and to provide potential interventions in at-risk donors.

Pretransplant C3d-Fixing Donor-Specific Anti-HLA Antibodies Are Not Associated with Increased Risk for Kidney Graft Failure.

Background Complement-fixing antibodies against donor HLA are considered a contraindication for kidney transplant. A modification of the IgG single-antigen bead (SAB) assay allows detection of anti-HLA antibodies that bind C3d. Because early humoral graft rejection is considered to be complement mediated, this SAB-based technique may provide a valuable tool in the pretransplant risk stratification of kidney transplant recipients.Methods Previously, we established that pretransplant donor-specific anti-HLA antibodies (DSAs) are associated with increased risk for long-term graft failure in complement-dependent cytotoxicity crossmatch-negative transplants. In this study, we further characterized the DSA-positive serum samples using the C3d SAB assay.Results Among 567 pretransplant DSA-positive serum samples, 97 (17%) contained at least one C3d-fixing DSA, whereas 470 (83%) had non-C3d-fixing DSA. At 10 years after transplant, patients with C3d-fixing antibodies had a death-censored, covariate-adjusted graft survival of 60%, whereas patients with non-C3d-fixing DSA had a graft survival of 64% (hazard ratio, 1.02; 95% confidence interval, 0.70 to 1.48 for C3d-fixing DSA compared with non-C3d-fixing DSA; P=0.93). Patients without DSA had a 10-year graft survival of 78%.Conclusions The C3d-fixing ability of pretransplant DSA is not associated with increased risk for graft failure.

PIRCHE-II Is Related to Graft Failure after Kidney Transplantation.

Individual HLA mismatches may differentially impact graft survival after kidney transplantation. Therefore, there is a need for a reliable tool to define permissible HLA mismatches in kidney transplantation. We previously demonstrated that donor-derived Predicted Indirectly ReCognizable HLA Epitopes presented by recipient HLA class II (PIRCHE-II) play a role in de novo donor-specific HLA antibodies formation after kidney transplantation. In the present Dutch multi-center study, we evaluated the possible association between PIRCHE-II and kidney graft failure in 2,918 donor-recipient couples that were transplanted between 1995 and 2005. For these donors-recipients couples, PIRCHE-II numbers were related to graft survival in univariate and multivariable analyses. Adjusted for confounders, the natural logarithm of PIRCHE-II was associated with a higher risk for graft failure [hazard ratio (HR): 1.13, 95% CI: 1.04-1.23, p = 0.003]. When analyzing a subgroup of patients who had their first transplantation, the HR of graft failure for ln(PIRCHE-II) was higher compared with the overall cohort (HR: 1.22, 95% CI: 1.10-1.34, p < 0.001). PIRCHE-II demonstrated both early and late effects on graft failure in this subgroup. These data suggest that the PIRCHE-II may impact graft survival after kidney transplantation. Inclusion of PIRCHE-II in donor-selection criteria may eventually lead to an improved kidney graft survival.

Development and Validation of a Multiplex Non-HLA Antibody Assay for the Screening of Kidney Transplant Recipients.

The best treatment for patients with end-stage renal disease is kidney transplantation. Although graft survival rates have improved in the last decades, patients still may lose their grafts partly due to the detrimental effects of donor-specific antibodies (DSA) against human leukocyte antigens (HLA) and to a lesser extent also by antibodies directed against non-HLA antigens expressed on the donor endothelium. Assays to detect anti-HLA antibodies are already in use for many years and have been proven useful for transplant risk stratification. Currently, there is a need for assays to additionally detect multiple non-HLA antibodies simultaneously in order to study their clinical relevance in solid organ transplantation. This study describes the development, technical details and validation of a high-throughput multiplex assay for the detection of antibodies against 14 non-HLA antigens coupled directly to MagPlex microspheres or indirectly via a HaloTag. The non-HLA antigens have been selected based on a literature search in patients with kidney disease or following transplantation. Due to the flexibility of the assay, this approach can be used to include alternative antigens and can also be used for screening of other organ transplant recipients, such as heart and lung.

Tacrolimus and posttransplant diabetes mellitus in renal transplantation.

The most prominent side effect of tacrolimus is the induction of posttransplant diabetes mellitus (PTDM). In this review, the authors discuss the incidence, mechanism, prevention, and treatment of tacrolimus-induced PTDM in renal patients.

Evaluating mechanisms of post-transplant diabetes mellitus.

Post-transplant diabetes mellitus (PTDM) is a frequent complication in renal transplantation. While both tacrolimus and ciclosporin are known to be associated with PTDM, the mechanisms underlying this metabolic disturbance and the relative contribution of concomitant corticosteroids have been unclear. At the University Hospital Maastricht, a series of studies have been conducted to investigate these issues. Administering tacrolimus to non-diabetic, dialysis patients was shown to result in a dose-related reduction in insulin secretion without altering insulin resistance. The patients who developed diabetes after transplantation already had impaired glucose metabolism pre-transplant. In a second study, corticosteroid withdrawal from tacrolimus-based immunosuppression reduced insulin resistance without changing insulin secretion. Moreover, reducing tacrolimus blood levels by 30% within the therapeutic window increased both insulin and C-peptide secretion by 24 and 36%, respectively. Accordingly, the effects of tacrolimus on insulin secretion are both dose dependent and reversible. A comparison of the effects of tacrolimus and ciclosporin on glucose metabolism revealed reduced insulin release with tacrolimus at week 3 post-transplant, but for the remainder of the 3 year follow-up there were no significant differences between the two treatment arms. Also, no difference was reported in glucose metabolism following conversion of stable renal recipients from ciclosporin to tacrolimus. Therefore, replacing tacrolimus with ciclosporin in patients experiencing glucose metabolism disturbances is unlikely to be helpful. In a recent study, early corticosteroid withdrawal from tacrolimus-based therapy resulted in a significantly lower incidence of new-onset diabetes mellitus than that achieved with a corticosteroid dose-tapering regimen. In conclusion, corticosteroid minimization plus dose-optimized tacrolimus immunosuppression is likely to be the best option for patients at risk of developing PTDM.

Increase in tacrolimus trough levels after steroid withdrawal.

Although there are experimental reports of cytochrome P450 3A4 iso-enzyme (CYP3A4) induction by glucocorticoids, there are no clinical reports about an interaction between tacrolimus and steroids. Therefore, tacrolimus trough level and dose were compared after dose-normalization before and after withdrawal of prednisolone. After withdrawal of 5 mg prednisolone, the median tacrolimus dose-normalized level increased by 14% in the retrospective ( n=54), and by 11% in the prospective ( n=8) part of the study. After withdrawal of 10 mg, this increase was 33% ( n=30) and 36% ( n=14), respectively. An additional pharmacokinetic part of the study ( n=8) revealed an 18% increase in AUC ( P=0.05) after withdrawal of 5 mg prednisolone, which is compatible with a reduced metabolism after steroid withdrawal. The significant increase in tacrolimus exposure after steroid withdrawal may on the one hand counteract the reduction in immunosuppression intended by steroid withdrawal, and, on the other hand, may result in an increase of serum creatinine which could be misinterpreted as rejection.

Early steroid withdrawal in renal transplantation with tacrolimus dual therapy: a pilot study.

BACKGROUND: With tacrolimus-based immunosuppression, it appears safe to withdraw steroids 3 to 6 months after renal transplantation. We hypothesized whether steroids could also be safely withdrawn early after transplantation. METHODS: Sixty-two patients (first or second transplant, with no previous immunological failure, and current panel reactive human leucocyte antigen [HLA] antibodies [PRA]<50%), treated with tacrolimus, were prospectively randomized to stop steroids (10 mg prednisolone) after day 7 posttransplantation (stop group [STOP], n=28) or to gradually wean off steroids in 3 to 6 months (tapering group [TAP], n=34). Analyses were performed on an intention-to-treat basis. RESULTS: After a median follow-up of 2.7 years, patient and graft survival were 97 and 90% and comparable between both groups (P =0.11 and P=0.13, respectively). The incidence of acute rejection was 29 (STOP) versus 33% (TAP) ( P=0.30). The time to the first rejection was a median of 35 days (STOP) versus 11 days (TAP) ( =0.19). The severity of the rejections (1997 Banff classification) was comparable (P =0.57). Creatinine clearance and proteinuria were similar (P >0.70). The incidence of infections was comparable ( P>0.10). The incidence of new-onset diabetes mellitus, defined as the use of antidiabetic medication, was 8.0 (STOP) versus 30.3% (TAP) (P =0.04). All cases occurred in the STOP group after 1 year, while all cases occurred in TAP in the first 4 months ( P<0.001). CONCLUSIONS: Compared with tapering in 3 to 6 months, stopping steroids 1 week posttransplantation results in comparable patient and graft survival and in a similar incidence of acute rejections. The incidence of new-onset diabetes may be reduced. The immunosuppressive benefit of adding 10 mg prednisolone to tacrolimus seems to be limited.

A late episode of post-transplant diabetes mellitus during active hepatitis C infection in a renal allograft recipient using tacrolimus.

BACKGROUND: An association between hepatitis C virus and (post-transplant) diabetes mellitus has been reported. METHODS: We report a patient on tacrolimus-based immunosuppression who developed an episode of post-transplant diabetes mellitus (PTDM) 2 years after renal transplantation, after contracting a hepatitis C infection. Her glucose metabolism was evaluated regularly by intravenous glucose tolerance tests before and after the PTDM episode. RESULTS: Before contracting hepatitis C, the patient's insulin resistance and insulin secretion were normal. After contracting hepatitis C, tacrolimus exposure increased, insulin resistance increased, and insulin secretion decreased markedly. Despite low tacrolimus exposure in the last 4 years, glucose metabolism did not recover completely. Although PTDM resolved and insulin resistance normalized, pancreatic beta cell secretion remained impaired by approximately 50% compared with the period before hepatitis C infection. CONCLUSION: After an initial increase in insulin resistance, insulin secretion decreased markedly in a patient who contracted hepatitis C 12 to 22 months after renal transplantation. This change resulted in an episode of PTDM. Increased tacrolimus exposure secondary to reduced cytochrome P-450 metabolism as a result of impaired hepatocellular function at the time of the development of PTDM seems a likely explanation for the marked decrease in insulin secretion. Viral toxicity to the beta cell might be an additional explanation. The latter might be suspected from several reports about an association between diabetes mellitus and hepatitis C in patients who do not use drugs that interfere with glucose metabolism.

Glucose metabolism in the first 3 years after renal transplantation in patients receiving tacrolimus versus cyclosporine-based immunosuppression.

The long-term effects of tacrolimus and cyclosporine on pancreatic islet cell function in renal transplant recipients are unclear. Therefore, a prospective, randomized, longitudinal study was performed that compared glucose metabolism in adult kidney allograft recipients on tacrolimus versus cyclosporine-based immunosuppression. Twenty-three white renal allograft recipients, randomized for either therapy with cyclosporine or tacrolimus, underwent intravenous glucose tolerance tests 6 times during the first 3 yr after transplantation. Concomitant therapy (low-dose steroids and azathioprine) was the same in both groups. Insulin sensitivity index (kG), insulin resistance (insulin/glucose ratio and homeostasis model assessment), and C-peptide and insulin secretion were calculated. Trough levels of tacrolimus and cyclosporine were measured. The occurrence of posttransplantation diabetes mellitus was prospectively monitored. Statistical analysis was performed by ANOVA for repeated measures, and parametric and nonparametric tests were also performed. Although only one patient treated with cyclosporine developed posttransplantation diabetes mellitus, kG levels were below normal in up to one-third of both patients who received tacrolimus and cyclosporine. The only significant difference between patients who received tacrolimus and those who received cyclosporine was in pancreatic secretion capacity at week 3 after transplantation, when the increment of C-peptide secretion was 57% lower and the increment of insulin secretion was 48% lower for patients receiving tacrolimus. In both groups, from week 3 to month 6, there was a tendency toward an increase in kG, despite a significant increase in fasting glucose and insulin resistance calculated by homeostasis model assessment. After month 6, there were no significant changes in any of the parameters of glucose metabolism, indicating that long-term use of either tacrolimus or cyclosporine does not cause chronic, cumulative pancreatic toxicity.

Glucose metabolism in renal transplant recipients on tacrolimus: the effect of steroid withdrawal and tacrolimus trough level reduction.

The relative role of steroids and tacrolimus in the development of glucose metabolic disorders and hyperlipidemia after renal transplantation has not yet been clearly established. Therefore, glucose metabolism was prospectively evaluated by intravenous glucose tolerance test, as was lipid profile, in fifteen white nondiabetic renal transplant recipients three times: before and after steroid withdrawal and after tacrolimus trough level reduction. After withdrawal of 10 mg of prednisolone, insulin resistance decreased (fasting C-peptide, 0.99 to 0.77 nmol/L [P < 0.0009]; fasting insulin, 9.5 to 8.1 mU/L [P = 0.09]; insulin/glucose ratio, 1.85 to 1.45 mU/mmol [P = 0.10]) and lipid levels decreased (total cholesterol, 5.1 to 4.2 mmol/L [P = 0.006]); HDL cholesterol, 1.4 to 1.1 mmol/L [P = 0.01]; LDL cholesterol, 3.0 to 2.5 mmol/L [P = 0.15]; triglycerides, 1.52 to 0.91 mmol/L [P = 0.02]). After tacrolimus trough level reduction from 9.5 to 6.4 ng/ml, pancreatic beta-cell secretion capacity improved (C-peptide secretion increased from 49.0 to 66.6 nmol x min/L [P = 0.04] and insulin secretion increased from 1134 to 1403 mU x min/L [P = 0.06]). HbA1c improved also, from 5.9 to 5.3% (P = 0.002). Lipids did not change. In conclusion, steroid withdrawal resulted in a decrease in insulin resistance and a reduction in lipids, and tacrolimus trough level reduction resulted in an improved pancreatic beta-cell secretion capacity. Therefore, these therapeutic measurements may contribute to the reduction of the cardiovascular morbidity and mortality in renal transplant recipients.