Fijter, J.W. de

The functional polymorphism Ala258Ser in the innate receptor gene ficolin-2 in the donor predicts improved renal transplant outcome (Article)

2012-09-15T00:00:00Z

BACKGROUND: Innate immunity plays a role in controlling adaptive immune responses. METHODS: We investigated the clinical relevance of single nucleotide polymorphisms in 22 genes encoding innate, secreted, and signaling pattern recognition receptors in a total of 520 donor-recipient pairs of postmortem, human leukocyte antigen-DR-compatible kidney transplantations. Associations with rejection incidence were tested in an a priori randomized training set and validation set. RESULTS: Polymorphisms in TLR-3 (rs3775296) in the recipients and in Ficolin-2 (rs7851696; Ala258Ser) and C1qR1 (rs7492) in the donors showed the strongest association with severe rejection. In multivariate analysis, presence of the Ficolin-2 Ala258Ser variant in the donor predicted lower incidence of severe rejection (odds ratio=0.3; 95% confidence interval, 0.1-0.9; P=0.024) and of graft loss (hazard ratio=0.5; 95% confidence interval, 0.2-1.0; P=0.046) independently of clinical risk factors. Ficolin-2 messenger RNA expression was detected in pretransplantation biopsies from 69 donor grafts. Serum and tissue Ficolin-2 levels were unaffected by genotype. Ficolin-2 protein, which bound to dying cells, was detected in donor kidneys in a passenger leukocyte-like pattern. Indeed, monocytes, monocyte-derived macrophages, and peripheral blood mononuclear cells expressed Ficolin-2. Donor grafts with the Ficolin-2 Ala258Ser variant contained significantly elevated expression of interleukin 6, having ascribed cytoprotective effects. It has been described that Ala258Ser leads to increased binding capacity of Ficolin-2 to N-acetylglucosamine. CONCLUSIONS: Presence of the Ficolin-2 Ala258Ser polymorphism in the donor independently predicts improved graft outcome. Based on mechanistic data, we propose that this functional polymorphism leads to more efficient handling of injured cells by phagocytozing cells, resulting in decreased intragraft exposure to danger signals and dampened alloimmune responses. Copyright

KIR-ligand mismatches are associated with reduced long-term graft survival in HLA-compatible kidney transplantation (Article)

2011-09-01T00:00:00Z

Natural killer (NK) cells are cytotoxic lymphocytes of the innate immune system with the ability to detect HLA class I disparities via killer-cell immunoglobulin-like receptors (KIR). To test whether such KIR-ligand mismatches contribute to the rejection of human solid allografts, we did a retrospective cohort study of 397 HLA-DR-compatible kidney transplantations and determined the KIR and HLA genotypes of recipients and the HLA genotypes of donors. In transplantations compatible for HLA-A, HLA-B and HLA-DR (n = 137), in which a role for T cells and HLA antibodies in rejection was minimized, KIR-ligand mismatches were associated with an approximately 25% reduction in 10-year death-censored graft survival (p = 0.043). This effect was comparable to the effect of classical HLA-A and HLA-B incompatibility, and in HLA-A,-B- incompatible transplantations (n = 260) no significant additional effect of KIR-ligand mismatches was observed. Multivariate Cox regression analysis confirmed the effect of KIR-ligand mismatching as an independent risk factor in HLA-A,-B,-DR-compatible transplantations (hazard ratio 2.29, range 1.03-5.10, p = 0.043). This finding constitutes the first indication that alloreactive NK cells may thwart the success of HLA-compatible kidney transplantations, and suggests that suppression of NK-cell activity can improve the survival of such kidney grafts. In this retrospective study, KIR and HLA typing reveals that in kidney transplantations compatible for HLA-A, B and DR, the presence of KIR-ligand mismatches is associated with a significant reduction in 10-year death-censored graft survival. See editorial by Rajalingam and Gebel on page 1771.

Effect of obesity on the outcome of kidney transplantation: A 20-year follow-up (Article)

2011-04-27T00:00:00Z

Background: Cardiovascular disease is both a major threat to the life expectancy of kidney transplant recipients and an important determinant of late allograft loss. Obesity is an important risk factor for cardiovascular disease. Methods: We investigated the relation between both pretransplant and 1-year posttransplant body mass index (BMI) with patient and renal graft survival in a cohort of 1810 adult patients. Sixty-one percent of all patients were men; median age (interquartile range [IQR]) was 46 years (35-56 years); median (IQR) pretransplant BMI was 23.0 kg/m (20.8-25.6 kg/m); 1 year after transplantation, the median (IQR) BMI had increased 1.6 kg/m (0.3-3.2 kg/m) and median (IQR) follow-up time was 8.3 years (5.3-12.0 years). We categorized BMI as follows: less than or equal to 20, more than 20 to less than or equal to 25 (normal), more than 25 to less than or equal to 30, and more than 30 (obesity) kg/m. Results: Using a Cox proportional hazards model, after adjustment for cardiovascular risk factors, the relative risks (95% confidence intervals) of death and death-censored graft failure during all follow-up for pretransplant obesity compared with normal BMI were 1.22 (0.86-1.74) and 1.34 (1.02-1.77), respectively; for obesity 1 year after transplantation compared with normal BMI, it was 1.39 (1.05-1.86) and 1.39 (1.10-1.74), respectively; and for change in BMI (per 5 kg/m increment) during the first year after transplantation, it was 1.23 (1.01-1.50) and 1.18 (1.01-1.38), respectively. Conclusions: One year posttransplant BMI and BMI increment are more strongly related to death and graft failure than pretransplant BMI among kidney transplant recipients. Patients with BMI more than 30 kg/m compared with a normal BMI have approximately 20% to 40% higher risk for death and graft failure. Copyright 2011 by Lippincott Williams & Wilkins.

Renal transplant patients at high risk of acute rejection benefit from adequate exposure to mycophenolic acid (Article)

2010-03-01T00:00:00Z

Background: To better define subpopulations in which achieving adequate mycophenolic acid (MPA) concentrations quickly would be important, a post hoc exploratory analysis on the fixed-dose concentration-controlled database was performed, comparing high-versus low-risk renal transplant patients. Methods: Renal transplant patients were treated with mycophenolate mofetil, corticosteroids, and cyclosporine A or tacrolimus. Patients were defined as "high risk" if they had one or more of the following characteristics: delayed graft function, second or third transplantation, panel reactive antibodies >15%, four or more human leukocyte antigen mismatches, or were of black race. Results: A total of 549 patients (61%) were classified as high risk, of whom 284 were on cyclosporine A treatment and 265 on tacrolimus. In high-risk patients, the difference in rejection incidence was 14.3% in the MPA-area under the concentration (AUC) less than 30 mg hr/L vs. 7.8% in the MPA-AUC more than or equal to 30 mg hr/L groups (P=0.025) during the first month after transplantation; whereas, in low-risk patients, there were similar rejection rates (5.7% vs. 4.5%). In the subgroup of high-risk tacrolimus-treated patients, the difference in acute rejection incidence in the first month between patients with MPA-AUC0-12 less than or more than or equal to 30 mg hr/L was most pronounced: 16 of 67 patients (23.9%) vs. 18 of 173 patients (10.4%); P=0.012. Conclusions: The incidence of acute rejection is higher in high-risk patients if MPA-AUC0-12 is below 30 mg hr/L. In contrast, a difference in acute rejection incidence in low-risk patients with MPA-AUC0-12 less than or more than or equal to 30 mg hr/L was not observed. This supports the use of a higher mycophenolate mofetil starting dose in selected patient populations early after transplantation. Copyright

UGT1A9 -275T>A/-2152C>T Polymorphisms Correlate With Low MPA Exposure and Acute Rejection in MMF/Tacrolimus-Treated Kidney Transplant Patients (Article)

2009-09-01T00:00:00Z

Mycophenolate mofetil (MMF) is an immunosuppressive drug commonly used in the context of kidney transplantation. Exposure to the active metabolite mycophenolic acid (MPA) is associated with risk of allograft rejection. MPA pharmacokinetics varies between individuals, the potential cause being the presence of genetic polymorphisms in key enzymes. We genotyped 338 kidney transplant patients for UGT1A8, UGT1A9, UGT2B7, and MRP2 polymorphisms and recorded MPA exposure and biopsy-proven acute rejections (BPARs) during a 1-year follow-up. Tacrolimus-treated patients who were UGT1A9 -275T>A and/or -2152C>T carriers displayed a 20% lower MPA area under the concentration-time curve from 0 to 12 h (AUC0-12) (P = 0.012). UGT1A9*3 carriers displayed a 49% higher MPA AUC0-12 when treated with tacrolimus and a 54% higher MPA AUC0-12 when treated with cyclosporine (P < 0.005). Cyclosporine-treated UGT1A8*2/*2 (518GG) patients had an 18% higher MPA AUC0-12 compared with noncarriers. Carrying the UGT1A9 -275T>A and/or -2152C>T polymorphism significantly predicted acute rejection in fixed-dose (FD) MMF-treated patients receiving tacrolimus (odds ratio 13.3, 95% confidence interval 1.1-162.3; P < 0.05). UGT1A9 -275T>A and/or -2152C>T genotyping may identify patients at risk of MPA underexposure and acute rejection when receiving treatment with MMF and tacrolimus.Clinical Pharmacology & Therapeutics (2009); advance online publication 03 June 2009. doi:10.1038/clpt.2009.83.

Pre-kidney-transplant blood transfusions do not improve transplantation outcome: A Dutch national study (Article)

2009-08-01T00:00:00Z

Background. Female renal transplant candidates are prone to be sensitized by prior pregnancies, and undetected historical sensitization might decrease transplantation outcome. Hypothesis of our study was that pre-transplant blood transfusions (PTFs) can elucidate historical sensitization and that the avoidance of the associated antigens can improve transplantation outcome.Methods. Data from all female non-immunized renal transplant candidates who received a random PTF (rPTF) (n = 620), matched PTF (mPTF) (one HLA-A and B and one HLA-DR match) (n = 86) or donor-specific blood transfusion (DST) (n = 100) between 1996 and 2006 were collected. Complement-dependent cytoxicity was used to detect anti-HLA antibodies. Sensitization and transplantation outcomes after a PTF were analyzed. Non-immunized female renal transplant recipients who did not receive a PTF were used as the control group.Results. In 165 patients, anti-HLA antibodies (IgG) were detected after the PTF. Both historical and primary sensitizations were found. A DST induced donor-specific anti-HLA antibodies in 25 of the DST recipients. Our policy did not improve transplantation outcome in recipients of a kidney from a deceased donor (n = 368) or in recipients of a living donor DST (n = 49) and mPTF (n = 66).Conclusions. A PTF did elucidate historical sensitization but induce primary sensitization as well. No beneficial effect of PTFs on transplantation outcome was found, and PTFs with the intention to detect historical sensitization are therefore not suggested.

Comparing mycophenolate mofetil regimens for de novo renal transplant recipients: The fixed-dose concentration-controlled trial (Article)

2008-10-27T00:00:00Z

BACKGROUND.: Fixed-dose mycophenolate mofetil (MMF) reduces the incidence of acute rejection after solid organ transplantation. The Fixed-Dose Concentration Controlled trial assessed the feasibility and potential benefit of therapeutic drug monitoring in patients receiving MMF after de novo renal transplant. METHODS.: Patients were randomized to a concentration-controlled (n=452; target exposure 45 mg hr/L) or a fixed-dose (n=449) MMF-containing regimen. The primary endpoint was treatment failure (a composite of biopsy-proven acute rejection [BPAR], graft loss, death, or MMF discontinuation) by 12 months posttransplantation. RESULTS.: Mycophenolic acid (MPA) exposures for both groups were similar at most time points and were below 30 mg hr/L in 37.3% of patients at day 3. There was no difference in the incidence of treatment failure (25.6% vs. 25.7%, P=0.81) or BPAR (14.9% vs. 15.5%, P>0.05) between the concentration-controlled and the fixed-dose groups, respectively. We did find a significant relationship between MPA-area under the concentration-time curve on day 3 and the incidence of BPAR in the first month (P=0.009) or in the first year posttransplantation (P=0.006). For later time points (day 10, month 1) there was no significant relationship between area under the concentration-time curve and BPAR (0.2572 and 0.5588, respectively). CONCLUSIONS.: There was no difference in the incidence of treatment failure between the concentration-controlled and the fixed-dose groups. The applied protocol of MMF dose adjustments based on target MPA exposure was not successful, partly because physicians seemed reluctant to implement substantial dose changes. Current initial MMF doses underexpose more than 35% of patients early after transplantation, increasing the risk for BPAR.

Associations between pre-kidney-transplant risk factors and post-transplant cardiovascular events and death (Article)

2008-10-01T00:00:00Z

The prevalence of cardiovascular risk factors in renal transplant candidates is high. A better understanding of the relation between these risk factors and cardiovascular morbidity and mortality is mandatory to improve transplantation outcome. In this retrospective cohort study 2187 adult patients who received a first kidney transplant between 1984 and 1997 were included. We analyzed the incidence of post-transplant cardiovascular events and tried to identify independent pretransplant risk factors for post-transplant cardiovascular events and all-cause mortality. The cumulative incidence of post-transplant cardiovascular events was 40%. The incidence was highest in the first 3 months after transplantation. Independent pretransplant risk factors for a post-transplant cardiovascular event were diabetic nephropathy [Hazard ratio (HR) 3.02; 95% CI 2.85-3.98], claudication [HR 2.17 (1.42-3.31)], cardiac event [HR 1.76 (1.32-2.33)], cerebrovascular accident HR 1.53 (1.03-2.28), time-on-dialysis [HR 1.06 (1.02-1.11)], recipient age [HR 1.04 (1.04-1.05)], and body mass index [HR 1.03 (1.00-1.05)]. Diabetic nephropathy and cardiovascular disease were also important predictors for all-cause mortality. Diabetic nephropathy and cardiovascular disease were the most important predictors for cardiovascular events and all-cause mortality after renal transplantation. Early treatment of cardiovascular risk factors and pretransplant cardiovascular evaluation might improve transplantation outcome.

CYP3A5 genotype is not associated with a higher risk of acute rejection in tacrolimus-treated renal transplant recipients (Article)

2008-04-01T00:00:00Z

OBJECTIVE: Patients expressing the tacrolimus-metabolizing enzyme, cytochrome P450 (CYP) 3A5, require more tacrolimus to reach target concentrations. We studied the influence of the CYP3A5*3 allele, which results in the absence of CYP3A5 protein, on tacrolimus dose and exposure, as well as the incidence of biopsy-proven acute rejection (BPAR) after renal transplantation. METHODS: A total of 136 patients participating in a prospective, randomized-controlled clinical trial with the primary aim of comparing the efficacy of a fixed-dose versus a concentration-controlled mycophenolate mofetil immunosuppressive regimen, were genotyped for CYP3A5*3. The patients described herein, participated in a pharmacogenetic substudy and were all treated with mycophenolate mofetil, corticosteroids and tacrolimus. Tacrolimus predose concentrations (C0) were measured on day 3 and 10, and month 1, 3, 6 and 12. RESULTS: Compared with CYP3A5*3/*3 individuals (n=110), patients carrying at least one CYP3A5*1 (wild-type) allele (CYP3A5 expressers; n=26) had a lower tacrolimus C0 on day 3 only (16.6 versus 12.3 ng/ml, respectively), whereas dose-corrected tacrolimus C0 were significantly lower in the latter group at all time points. After day 3, the overall daily tacrolimus dose was 68% higher in CYP3A5 expressers (P<0.001). The incidence of BPAR was comparable between CYP3A5 expressers and nonexpressers (8 versus 16%, respectively; P=0.36). CONCLUSION: We conclude that patients expressing CYP3A5 need more tacrolimus to reach target concentrations and have a lower tacrolimus exposure shortly after transplantation. This delay in reaching target concentrations, however, did not result in an increased incidence of early BPAR and therefore, genotyping for CYP3A5 is unlikely to improve short-term transplantation outcome.

Plasma concentrations of mycophenolic acid acyl glucuronide are not associated with diarrhea in renal transplant recipients (Article)

2007-07-01T00:00:00Z

The aim of this study was to determine whether plasma concentrations of the acyl (AcMPAG) and phenolic (MPAG) glucuronide metabolites of mycophenolic acid (MPA) were related to diarrhoea in renal transplant patients on mycophenolate mofetil (MMF) with cyclosporine (CsA) or tacrolimus (TCL). Blood samples (0, 30, 120 min) were taken at days 3, 10, week 4, months 3, 6 and 12 for determination of MPA, MPAG and AcMPAG. MPA-AUC was estimated using validated algorithms. Two hour AUCs were calculated for MPAG and AcMPAG. Immunosuppressive therapy consisted of CsA/MMF (n = 110) and of TCL/MMF (n = 180). In 70/290 (24%) patients 86 episodes of diarrhoea were recorded during 12 months. Significantly more patients on TCL (31.1%) suffered from diarrhea compared to CsA (12.7%). MMF dose, MPA-AUC and the 2 h AUCs of MPAG and AcMPAG did not differ between patients with and without diarrhoea. Plasma AcMPAG and MPAG concentrations were substantially higher in patients on CsA compared with TCL, while MPA-AUC was lower in the former group. These data support the concept that CsA inhibits the biliary excretion of MPAG and AcMPAG, thereby potentially reducing the risk of intestinal injury through enterohepatic recycling of MPA and its metabolites.

Quantification of dendritic cell subsets in human renal tissue under normal and pathological conditions (Article)

2007-05-14T00:00:00Z

Dendritic cells (DCs) play critical roles in immune responses and can be distinguished in two major subsets, myeloid and plasmacytoid DCs. Although the presence of DC in all peripheral organs, including the kidney, has been well documented, no accurate estimates of DC subsets in human kidneys have been reported. This study shows a detailed analysis of DC subsets in cryosections of human renal tissue. The cortex of normal kidneys contains at least two different HLA-DR+myeloid DC subtypes characterized by BDCA-1+DC-SIGN+and BDCA-1+DC-SIGN-. The staining for DC-SIGN completely overlapped with CD68 in the renal interstitium. Unexpectedly, BDCA-2+DC-SIGN-plasmacytoid DCs are also abundantly present. Both subsets are located in the tubulo-interstitium often with a high frequency around, but rarely observed within glomeruli. Quantification of BDCA-1+, DC-SIGN+, and BDCA-2+cells in normal human renal tissue (pretransplant biopsy living donors; n=21) revealed that BDCA-1 is about four times as frequently present as BDCA-2. A preliminary cross-sectional analysis of DC in diseased kidneys, including rejection and immunoglobulin A nephropathy, revealed that the number of DC as well as their anatomical distribution might change under pathophysiological conditions. In conclusion, we show that human kidneys contain a dense network of myeloid and plasmacytoid DCs and provide the tools for phenotyping and enumeration of these cells to better understand interindividual differences in immune responses.