Donor polymorphisms of toll-like receptor 4 associated with graft failure in liver transplant recipients.

There have been many reports showing significant associations between recipient genetic variants and allograft outcomes, including acute rejection and graft failure, but less is known about the contribution of the donor genotype. We analyzed 37 single-nucleotide polymorphisms (SNPs) within the toll-like receptor 4 (TLR4) gene from deceased donor liver allografts transplanted into 738 recipients to determine their effects on liver graft failure (LGF). Two SNPs exhibited a significant association with LGF after adjustments for donor race and recipient race and corrections for multiple test comparisons: rs11536865 [hazard ratio (HR) = 2.5, P = 0.0003] and rs5030717 (HR = 1.67, P = 0.0008). An additional SNP, rs913930, exhibited a significant association in Caucasian donors (HR = 1.62, P = 0.0006), and 2 SNPs exhibited a suggestive association in African American donors: rs11536865 (HR = 2.45, P = 0.002) and rs5030717 (HR = 2.32, P = 0.002). Additionally, the liver donor risk index (HR = 2.56, 95% confidence interval = 1.54-4.26, P = 0.0003) and the recipient hepatitis C virus (HCV) status (HR = 1.53, 95% confidence interval = 1.04-2.24, P = 0.032) increased the risk of all-cause LGF in a Cox proportional hazards model adjusted for recipient race. Donor polymorphisms in TLR4 could be important factors in modulating TLR4 activity and, therefore, affect the risk of graft loss. Additionally, there is a suggestion of an interaction between polymorphisms within TLR4 and the HCV status.

Antibodies reactive to non-HLA antigens in transplant glomerulopathy.

Although T and B cell alloimmunity contribute to transplant injury, autoimmunity directed at kidney-expressed, non-HLA antigens may also participate. Because the specificity, prevalence, and importance of antibodies to non-HLA antigens in late allograft injury are poorly characterized, we used a protein microarray to compare antibody repertoires in pre- and post-transplant sera from several cohorts of patients with and without transplant glomerulopathy. Transplantation routinely induced changes in antibody repertoires, but we did not identify any de novo non-HLA antibodies common to patients with transplant glomerulopathy. The screening studies identified three reactivities present before transplantation that persisted after transplant and strongly associated with transplant glomerulopathy. ELISA confirmed that reactivity against peroxisomal-trans-2-enoyl-coA-reductase strongly associated with the development of transplant glomerulopathy in independent validation sets. In addition to providing insight into effects of transplantation on non-HLA antibody repertoires, these results suggest that pretransplant serum antibodies to peroxisomal-trans-2-enoyl-coA-reductase may predict prognosis in kidney transplantation.

Cost-related immunosuppressive medication nonadherence among kidney transplant recipients.

BACKGROUND AND OBJECTIVES: Immunosuppressive medications are essential in preventing kidney transplant rejection. Continuous insurance coverage for outpatient immunosuppressive medications remains a major issue. The objective of this study was to establish the prevalence and consequences of cost-related immunosuppressive medication nonadherence. DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS: A descriptive survey of all U.S. kidney transplant programs (n = 254) was conducted. The response rate for the survey exceeded 99%. The main outcome measures included the following: transplant recipient concerns related to medication costs, ability to pay for medications, medication nonadherence and its consequences, and failure of transplant centers to place patients on the transplant waiting list. RESULTS: Continuous insurance coverage for outpatient immunosuppressive drugs is a problem having potentially grave consequences for the majority of kidney transplant recipients. More than 70% of kidney transplant programs report that their patients have an extremely or very serious problem paying for their medications. About 47% of the programs indicate that more than 40% of their patients are having difficulty paying for their immunosuppressive medications. In turn, 68% of the programs report deaths and graft losses attributable to cost-related immunosuppressive medication nonadherence. Some of the problems identified here are more significant for adult than pediatric patients. CONCLUSIONS: The prevalence and consequences of cost-related immunosuppressive medication nonadherence among kidney transplant recipients have now been documented. The results presented here should serve as the necessary impetus for the development of health care policies supporting Medicare coverage of immunosuppressive medications for the life of the transplanted kidney.

A single nucleotide polymorphism of Toll-like receptor 4 identifies the risk of developing graft failure after liver transplantation.

BACKGROUND & AIMS: While studies in animal models have linked Toll-like receptor (TLR) 4 signaling to the pathophysiology of ischemia/reperfusion (IR) injury and liver fibrosis, the relevance of TLR4 activation after human liver transplantation is unknown. The TLR4 single nucleotide polymorphism (SNP) D299G is situated within the extracellular domain and diminishes receptor binding to danger-associated molecular patterns. METHODS: We studied the influence of TLR4 D299G on IR injury and graft survival in 430 deceased donor LT recipients. Compared with livers expressing wild-type (WT) alleles, livers with a TLR4 loss-of-function allele were significantly more likely to have initial good graft function (IGGF) (OR 2.20, p=0.01). In contrast, there was no effect of recipient TLR4 genotype on the rate of IGGF. RESULTS: The effect of TLR4 D299G on long-term graft survival was analyzed based on hepatitis C virus (HCV) serostatus. In HCV infected recipients, multivariate Cox regression analysis demonstrated a significant association between the presence of recipient, but not donor TLR4 D299G and long-term graft failure (HR 2.48, CI 1.28-4.81; p=0.007). There was no difference in graft survival between TLR4 mutant and WT recipients among non-HCV infected recipients. CONCLUSIONS: Collectively, these results demonstrate the differential effects of donor and recipient TLR4 signaling in human liver transplantation. Donor TLR4 contributed to sterile injury following cold preservation and the recipient TLR4 genotype was linked with poor allograft survival among HCV infected recipients.

Tubular expression of KIM-1 does not predict delayed function after transplantation.

Injured epithelial cells of the proximal tubule upregulate the glycoprotein kidney injury molecule 1 (KIM-1), suggesting its potential as a biomarker of incipient kidney allograft injury. It is unknown whether KIM-1 expression changes in kidney allografts with delayed graft function (DGF), which often follows ischemia-reperfusion injury. Here, we prospectively measured KIM-1 RNA and protein expression in preperfusion biopsies of 30 living- and 85 deceased-donor kidneys and correlated the results with histologic and clinical outcomes after transplantation. We detected KIM-1 expression in 62% of deceased-donor kidneys and only 13% of living-donor kidneys (P < 0.0001). The level of KIM-1 expression before reperfusion correlated inversely with renal function at the time of procurement and correlated directly with the degree of interstitial fibrosis. Surprising, however, we did not detect a significant correlation between KIM-1 staining intensity and the occurrence of DGF. Our findings are consistent with a role for KIM-1 as an early indicator of tubular injury but do not support tissue KIM-1 measurement before transplantation to identify kidneys at risk for DGF.

Donor Toll-like receptor 4 contributes to ischemia and reperfusion injury following human kidney transplantation.

While studies in animal models have linked Toll-like receptor (TLR) 4 signaling to kidney injury induced by ischemia and reperfusion, the relevance of TLR4 activation to allograft injury in human kidney transplants is unknown. Here we show that TLR4 is constitutively expressed within all donor kidneys but is significantly higher in deceased-, compared with living-donor organs. Tubules from deceased- but not living-donor kidneys also stained positively for high-mobility group box-1 (HMGB1), a known endogenous TLR4 ligand. In vitro stimulation of human tubular cells with HMGB1, in a TLR4-dependent system, confirmed that HMGB1 can stimulate proinflammatory responses through TLR4. To assess the functional significance of TLR4 in human kidney transplantation, we determined whether TLR4 mutations that confer diminished affinity for HMGB1 influence intragraft gene-expression profiles and immediate graft function. Compared with kidneys expressing WT alleles, kidneys with a TLR4 loss-of-function allele contained less TNFalpha, MCP-1, and more heme oxygenase 1 (HO-1), and exhibited a higher rate of immediate graft function. These results represent previously undetected evidence that donor TLR4 contributes to graft inflammation and sterile injury following cold preservation and transplantation in humans. Targeting TLR4 signaling may have value in preventing or treating postischemic acute kidney injury after transplantation.

Genetic polymorphisms and the fate of the transplanted organ.

There has been an abundance of publications describing genetic variability in molecules affecting innate and adaptive immunity, pharmacogenetics, and other nonimmunological factors like the renin-angiotensin aldosterone system, coagulation, and fibrosis markers. Studies indicated some associations between polymorphisms in these candidate genes with outcomes in organ transplantation and underlined a potential role of genetic variability in transplantation. To be clinically applicable, large prospective studies must be performed to better define the potential benefits of genotyping on these genetic markers and clinical outcomes. The purposes of this review are to summarize recent data describing associations of polymorphisms in both immunological and nonimmunological molecules with transplant outcomes, with a particular emphasis on renal transplantation, and discuss limitations and clinical implications.

No effect of C-reactive protein (CRP) haplotypes on CRP levels and post-transplant morbidity and mortality in renal transplantation.

Increased serum C-reactive protein (CRP) levels have been associated with all-cause and cardiovascular mortality after kidney transplantation. As genetic variations within the CRP gene determine CRP serum levels, we analyzed the association of both serum CRP levels, and post-transplant morbidity/mortality with CRP-genotypes/haplotypes. We determined CRP levels pretransplant, at 3 and 6 months post-transplant in 402 first kidney recipients, genotyped the three functionally distinct polymorphisms, and subsequently reconstructed the different haplotypes. Four different CRP-haplotypes were observed with a frequency >1%: CGC (33.3%), CGT (30.2%), CAT (29.7%) and GGT (6.8%). CRP levels pretransplantation or 3 and 6 months post-transplant were not different in patients with different CRP-haplotypes. Furthermore, no association of CRP-haplotypes/diplotypes was found with acute rejection, delayed graft function, all-cause mortality or cardiovascular events. In our renal transplant population, we found no association of CRP-haplotypes/diplotypes with either CRP levels or with post-transplant morbidity/mortality. In this inflammation-prone population, rather small genetically determined differences in serum CRP observed in normal populations presumably are overridden by background inflammation. Life long genetically determined increased serum CRP levels appear not to have an impact in our study, implying that CRP is more likely only a marker of current inflammation than a causative agent of cardiovascular morbidity and mortality.

Impact of NOD2/CARD15 haplotypes on the outcome after kidney transplantation.

Chronic allograft nephropathy and (cardiovascular) death with functioning graft are major causes of late graft loss. NOD2/CARD15 (nucleotide oligomerization domain-2/caspase-recruiting activating domain-15), an intracellular receptor that is part of the innate immunity repertoire, has convincingly been shown to be involved in infection/inflammation-associated diseases. Specifically, NOD2/CARD15 polymorphisms are clearly associated with Crohn's disease and transplant-associated mortality after bone marrow transplantation. The aim of this study was to clarify the relevance of NOD2/CARD15-haplotypes in kidney transplantation. Three hundred fifty-two patients receiving their first kidney transplant were genotyped for the three major NOD2/CARD15 polymorphisms, R702W, G908R, and 1007fs with subsequent reconstruction of the different haplotypes. Four different NOD2/CARD15 haplotypes were observed in our population [CG(-): 89.8%, CGC: 3.5%, CC(-): 1.6%, TG(-): 5.1%]. After stratifying the different haplotypes into diplotypes (wild type: CG(-)/CG(-), n=284, mutated haplotype, n=68) we found a significant association with all-cause and cardiovascular mortality, also after adjusting to different covariates, and (only) in univariate analysis with graft survival. In conclusion, we found different effects of the NOD2/CARD15 haplotypes on disorders, like cardiovascular and all-cause mortality,which may be considered at least in part as chronic inflammation-driven. Further studies are needed to confirm and work out the association between these disorders and the NOD2/CARD15 haplotypes.