Genetic variability of major inflammatory mediators has no impact on the outcome of kidney transplantation

Influence of Interferon Gamma +874 T>A (rs2430561) Polymorphism on Renal Allograft Rejection: A Meta-analysis

BACKGROUND

Reported associations of the interferon gamma (IFNG) +874T/A (rs2430561) polymorphism with post-kidney transplantation allograft rejection (AR) have been inconsistent, prompting a meta-analysis to obtain more precise estimates.

METHODS

Eighteen articles (22 studies) were included in the meta-analysis. Operating on the hypothesis that IFNG rs2430561 either increases or reduces AR risk, we used a genetic model-free approach to estimate odds ratios (ORs) and 95% confidence intervals (CIs). Subgrouping was based on ethnicity (white, Middle Eastern, black, and mixed) and rejection type (ACR: acute rejection and CHR: chronic rejection). Quality of the associative effects was assessed with sensitivity treatment and test for publication bias.

RESULTS

The overall analysis in the dominant model indicated increased risk (OR = 1.26; P^a = .02) was validated in the ACR subgroup (OR = 1.29; P^a = .01), which contrasted with the CHR subgroup, with a nonsignificant effect indicating reduced risk (OR = 0.83; P^a = .68). Only the black subgroup showed significant increased risk (OR = 2.87; P^a = .04), but the association was tenuous on account of low sample size (n = 2) and imprecise effect (95% CI, 1.07-7.73).

CONCLUSIONS

Increased risk associations (overall and ACR) of IFNG rs2430561 with AR is significant, robust, statistically powered, and lacking bias. Contrasting ACR (1.3-fold increased risk) and CHR (7% protective) effects may be clinically relevant in the genetics of renal transplantation.

Acute rejection in kidney transplantation and the evaluation of associated polymorphisms (SNPs): the importance of sample size

Background Acute rejection (AR) is one of the most frequent complications after kidney transplantation (KT). Scientific evidence reports that some single-nucleotide polymorphisms (SNPs) located in genes involved in the immune response and in the pharmacokinetics and pharmacodynamics of immunosuppressive drugs are associated with rejection in renal transplant patients. The aim of this study was to evaluate some SNPs located in six genes: interleukin-10 (IL-10), tumor necrosis factor (TNF), adenosine triphosphate-binding cassette sub-family B member 1 (ABCB1), uridine diphosphate glucuronosyltransferase family 1 member A9 (UGT1A9), inosine monophosphate dehydrogenase 1 (IMPDH1) and IMPDH2. Methods We enrolled cases with at least one AR after KT and two groups of controls: patients without any AR after KT and healthy blood donors. Genetic analysis on DNA was performed. The heterozygosity (HET) was determined and the Hardy-Weinberg equilibrium (HWE) test was performed for each SNP. The sample size was calculated using the QUANTO program and the genetic associations were calculated using the SAS program (SAS Institute Inc., Cary, NC, USA). Results In our previous preliminary study (sample size was not reached for cases), the results showed that patients with the C allele in the SNP rs1045642 and the A allele in the SNP rs2032582 of the ABCB1 gene had more frequent AR. In contrast, with the achievement of sample size, the trend of the previous data was not confirmed. Conclusions Our study highlights a fundamental aspect of scientific research that is generally presumed, i.e. the sample size of groups enrolled for a scientific study. We believe that our study will make a significant contribution to the scientific community in the discussion of the importance of the analysis and the achievement of sample size to evaluate the associations between SNPs and the studied event.

Relationship between TGF-β1 + 869 T/C and + 915 G/C gene polymorphism and risk of acute rejection in renal transplantation recipients

BACKGROUND

This meta-analysis was conducted to assess the relationship between the transforming growth factor-beta 1 (TGF-β1) + 869 T/C gene polymorphism, + 915 G/C gene polymorphism, and the susceptibility of acute rejection in the recipients with renal transplantation.

METHODS

Relevant studies were searched and identified from the Cochrane Library and PubMed, and eligible investigations were recruited and data were calculated by meta-analysis.

RESULTS

In this study, we found no relationship between either TGF-β1 + 869 T/C or TGF-β1 + 915 G/C gene polymorphism and acute rejection susceptibility in patients with renal transplantation. No association between either gene polymorphism and acute rejection susceptibility in patients with renal transplantation in Caucasian, Asian, or African populations individually was found.

CONCLUSION

The TGF-β1 + 869 T/C and + 915 G/C gene polymorphisms are not associated with acute rejection susceptibility in recipients with renal transplantation.

Association Between Cytokines and Their Receptor Antagonist Gene Polymorphisms and Clinical Risk Factors and Acute Rejection Following Renal Transplantation

BACKGROUND Acute rejection (AR) after renal transplantation affects both patient and graft survival. There is growing evidence of the genetic association between cytokine or its receptor antagonist and AR in solid organ transplantation. The objectives of this study were to investigate the role of recipient TNF β, IL-10, IL-1β, and IL-1 receptor antagonist (ra) gene polymorphism, as well as traditional clinical variables such as panel-reactive antibody (PRA) levels, donor type, and HLA mismatches in AR following renal transplantation. MATERIAL AND METHODS TNF β (+252A/G), IL-10 (-592A/C), IL-1β (-511C/T) and IL-1ra (86 bp VNTR) gene polymorphisms were determined in 195 renal allograft recipients with and without AR, using PCR. Both these genotypic variants and clinical risk factors were investigated for correlation with AR within the first year after renal transplantation. RESULTS Patients with increased pre-transplant PRA levels (P<0.001) and donor type (P=0.012) were prone to the development of AR. After adjusting for all variables of P<0.2, a PRA level >10% (OR=4.515, 95% confidence intervals=1.738-11.727, P=0.002) and the receipt of a graft from a donation after cardiac death (DCD) donor (OR=2.437, 95% confidence intervals=1.047-5.673, P=0.039) remained significantly associated with AR in a multivariate logistic regression analysis. No correlation could be found between recipients with an episode and absence of acute rejection and the gene polymorphisms of these cytokines investigated in the present study. CONCLUSIONS This study shows that the presence of increased pre-transplant levels of PRA and the receipt of a graft from DCD donor other than cytokine gene polymorphisms are significant risk factors for AR in renal transplantation. To reduce the occurrence of AR, clinicians should take necessary measures to lower the PRA levels and pay more attention to patients who received a graft from a DCD donor.

The Polymorphism -308G/A of Tumor Necrosis Factor-α Gene Modulates the Effect of Immunosuppressive Treatment in First Kidney Transplant Subjects Who Suffer an Acute Rejection

The -308G/A SNP of tumor necrosis factor-alpha (TNF-α) gene affects TNF-α production. As its impact on transplant outcome remains open to debate, we decided to genotype it in a cohort of transplant subjects. A retrospective analysis of 439 first kidney recipients randomly divided into two subgroups (discovery and validation cohorts) was performed to identify the best predictors of acute rejection (AR). The effect on transplant outcome was analyzed by an adjusted logistic regression model. Carriers of the A allele, associated with elevated TNF-α production, presented a higher risk of AR (OR = 2.78; 95% CI = 1.40-5.51). Logistic regression analyses for AR showed an interaction between the polymorphism and treatment with thymoglobulin (p-interaction = 0.03). In recipients who did not receive thymoglobulin, carriers of A allele had higher risk of AR (OR = 4.05; 95% CI = 1.76-9.28). Moreover, carriers of A allele not treated with thymoglobulin presented higher risk of AR than those who received thymoglobulin (OR = 13.74; 95% CI = 1.59-118.7). The AUC of the model in the discovery cohort was 0.70 and in the validation cohort was 0.69. Our findings indicate that the -308G/A TNF-α polymorphism is associated with AR risk and it modulates the effectiveness of thymoglobulin treatment. This pharmacogenetic effect lets us propose this SNP as a useful predictor biomarker to tailor immunosuppressive regimens.

Association of cytokine/costimulatory molecule polymorphism and allograft rejection: a comparative review

One reason for genetic variations among human individuals is SNP which may confer diverse disease susceptibility or resistance in a population. Genetic variations in a key immunoregulatory agent can manifest various immunological responses, such as graft rejection. In fact, the outcome of organ transplantation can be impacted by several genetic causes including polymorphisms in genes encoding cytokines and costimulatory molecules in the donor or recipient. Thus, it can be helpful to contemplate the SNPs relating to these immunological determinants in order to achieve an improved transplantation therapy.

Association between transforming growth factor beta-1 +869T/C polymorphism and acute rejection of solid organ allograft: A meta-analysis and systematic review

BACKGROUND

Transforming growth factor beta-1(TGFB1) is involved in the acute rejection (AR) episodes of solid organ transplant recipients. However, results from published studies on the association between donor/recipient TGFB1 +869T/C polymorphism and AR risk are conflicting and inconclusive.

METHODS

PUBMED, EMBASE, CNKI and Wanfang Database were searched to identify eligible studies investigating the association between donor/recipient TGFB1 +869T/C polymorphism and AR risk. Statistical analysis was performed by using STATA 10.0.

RESULTS

A total of 29 studies were included. Overall, the donor TGFB1 +869T/C polymorphism was significantly associated with AR risk in heterozygote comparison (CT vs. TT: OR = 1.67, 95%CI, 1.17-2.39; P heterogeneity=0.285) and dominant model (CC vs.

TC/TT

OR = 1.47, 95%CI, 1.05-2.06; P heterogeneity=0.445). In addition, subgroup analysis revealed that CT variant (CT vs. TT: OR = 1.97, 95%CI, 1.20-3.25; P heterogeneity = 0.777) and CC/CT genotype (CC/CT vs. TT: OR = 1.72, 95%CI, 1.07, 2.78; P heterogeneity = 0.619) within donors contributed to higher risk of AR in recipients administrated with CsA or FK506, compared with those applied only CsA. On the other hand, no significant association between recipient TGFB1 +869T/C polymorphism and AR was detected in all genetic models.

CONCLUSIONS

This meta-analysis and systematic review suggested that donor TGFB1 +869T/C polymorphism was significantly associated with AR of solid organ transplant recipients, and especially among patients in CsA/FK 506 group compared with those in CsA group.

Association between interferon gamma +874 T>A polymorphism and acute renal allograft rejection: evidence from published studies

Interferon gamma is involved in the acute rejection (AR) episodes of transplant recipients. However, results from published studies on the association of interferon gamma (IFNG) +874 T>A (rs2430561) polymorphism with AR of renal allograft are conflicting. To investigate the association between IFNG +874 T>A polymorphism with AR after renal transplantation, relevant studies were selected from PUBMED, EMBASE, Wanfang database and China National Knowledge Infrastructure until March 1st 2013. According the predesigned selection criteria, a total of 525 AR cases and 1,126 non-AR cases from 13 case-control studies were included to identify the strength of association with odds ratio (OR) and 95 % confidence intervals (95 % CI). Overall, a significant correlation between IFNG +874 T>A polymorphism and susceptibility to AR was detected (T allele vs. A allele: OR = 1.19, 95 % CI 1.02-1.38; TT/AT vs. AA: OR = 1.36, 95 % CI 1.07-1.73; TT vs. AA: OR = 1.42, 95 % CI 1.05-1.93; AT vs. AA: OR = 1.30, 95 % CI 1.01-1.68). In addition, ethnicity subgroup analysis revealed that high produce genotype (TT/AT) was associated with an increased risk of AR for Caucasians (TT/AT vs. AA: OR = 1.56, 95 % CI 1.14-2.12; TT vs. AA: OR = 1.64, 95 % CI 1.18-2.26). Furthermore, donor source subgroup analysis observed an increased risk for patients undergoing cadaveric kidney transplantation (TT/AT vs. AA: OR = 1.90, 95 % CI 1.12-3.24; TA vs. AA: OR = 2.16, 95 % CI 1.24-3.74). In conclusion, this meta-analysis suggested that IFNG +874 T>A polymorphism was associated with AR of renal transplant recipients, especially among Caucasians and those receiving cadaveric renal allograft. Additional well-designed studies with large sample size are warranted to validate our conclusion.

The effect of chemokine receptor gene polymorphisms (CCR2V64I, CCR5-59029G>A and CCR5Δ32) on renal allograft survival in Pakistani transplant patients

BACKGROUND

Gene polymorphisms of the chemokine receptors CCR2 and CCR5 (CCR2V64I, CCR5-59029G>A and CCR5Δ32) have been shown to be associated with renal allograft rejection. The aim of this study was to investigate the association of these polymorphisms with allograft rejection among Pakistani transplant patients.

METHOD

A total of 606 renal transplant patients and an equal number of their donors were included in this study. DNA samples were used to amplify polymorphic regions of CCR2V64I, CCR5-59029G>A and CCR5Δ32 by polymerase chain reaction using sequence specific primers. The amplified products of CCRV64I and CCR5-59029G>A were digested with restriction enzymes (BsaB1 and Bsp12861) respectively. The CCR5Δ32 genotypes were determined by sizing the PCR amplicons. The association of these polymorphisms with the biopsy proven rejection and other clinical parameters was evaluated using the statistical software SPSS v.17.

RESULTS

In this study, the G/G genotype of CCR2V64I was associated with a high frequency of allograft rejection (p=0.009; OR=2.14; 95% CI=1.2-3.7). Rejection episode(s) in the GA+AA genotypes were found to be significantly lower as compared to the GG genotype (p=0.009; OR=0.4; 95% CI=0.2-0.8). The Kaplan-Meier curve also indicated a reduced overall allograft survival for patients with the G/G genotype of CCR2V64I (59.2 ± 1.4 weeks, log p=0.008). There was a significant association with rejection by female donors possessing the CCR2 GG genotype (p=0.02; OR=2.6; CI=1.1-6.3) and male donors with the CCR5-59029 GG genotype (p=0.004; OR=1.7; CI=1.03-3.01).

CONCLUSION

This study shows an association of the CCR2V64I (G/G) genotype with renal allograft rejection. However, no such association was found for the CCR5 gene polymorphisms. Therapeutic interventions such as blocking the CCR2 receptor (especially G polymorphism) may yield better survival of renal allograft in this patient group. Further, chemokine receptors may be added to the spectrum of the immunogenetic factors that are known to be associated with renal allograft rejection.

The role of CCR5 in HCV infection

Efficient recruitment and activation of immuno-competent cells is crucial for an effective immune response to hepatitis C virus (HCV) infection. Chemokines and chemokine receptors have been shown to be critically involved in these processes.

The CCR5 chemokine receptor is expressed on several cells of the immune system and has been suggested to influence the susceptibility to HCV infection as well as natural course and progression of hepatitis C. However, these reports are still controversial.

This review will summarize and discuss the available data regarding the potential role of CCR5 and its ligands in hepatitis C.

Update on the clinical pharmacogenomics of organ transplantation

Organ transplantation suffers from a static graft and patient survival rate, and a high incidence of serious adverse drug effects. The pharmacogenomics of organ transplantation has emerged only recently and is complementary to the immunogenetic information that has accumulated over the past decade. Gene polymorphism studies have focused on the genes that interact across the group of immunosuppressants, including ciclosporin, tacrolimus, sirolimus and corticosteroids. The polymorphisms that hold the most potential for use in a drug selection algorithm are in genes CYP3A5, ABCB1, IMPDH1 and IMPDH2, and cytokines and growth factors. Gene-expression arrays have led to gene-expression testing, such as the use of AlloMap((R)) with heart transplant patients. The expanded use of gene-expression assays, proteomics and drug selection algorithms in organ transplantation will progress slowly and may be outpaced by drug test co-development programs for new transplant drugs. In the future, clinical pharmacogenomics will be a routine part of patient care for organ transplant patients.

Genetic prediction of renal transplant outcome

PURPOSE OF REVIEW

In the present study, we reviewed recent publications regarding potential genetic predictors of transplant outcome, including acute rejection, metabolism of immunosuppressive medications, long-term transplant outcome, and posttransplant complications.

RECENT FINDINGS

Recent studies are based on the candidate gene analysis; specifically, cytokine genes and innate immune response molecules present popular targets for studies of acute rejection and long-term outcome. Pharmacogenomic studies are mostly focused on the genes of drug targets or the corresponding enzymes metabolizing the drug. Posttransplant complications (i.e. infections, diabetes, and malignancies) are associated with a variety of genes of different pathways. Most of the studies are based on just recipient, but not donor, genotype analysis. Positive results are balanced by reports of no association when evaluating the same genetic polymorphisms. Some of the reports might be affected by insufficient study design, including small sample size, lack of adjustment for potential confounders, and multiple comparisons.

SUMMARY

The field remains controversial because of differences in populations, study design, and statistical methods. Studies are based on candidate gene analysis; however, genome-wide association studies are lacking. Future research should be directed at better designed studies, larger sample size, evaluating both recipients and donors, and implementation of genome-wide association studies.

Effect of cytokine and pharmacogenomic genetic polymorphisms in transplantation

Consolidating the information that we have on pharmacogenetics and on cytokine genetics to produce patient-oriented individualized drug regimens is an important challenge in transplantation medicine. Using a multi-variant approach based on genetic profile and other relevant clinical factors a score system may be developed to predict the severity of rejection, infection, or other complications associated with transplantation. The ultimate goal of these studies is to improve patient outcome through individualized drug regimens.

Immunosuppressive drug therapy and subclinical acute renal allograft rejection: impact and effect

The incidence of subclinical acute rejection (SCAR) varies between 5% and 15% with current maintenance immunosuppressive drug regimens. Despite many similarities between SCAR and clinical acute rejection exist, the inflammatory activated cell infiltrates are not completely identical while graft cytokine profiles and counteractive immune responses are characterized by subtle differences that could explain why SCAR is not accompanied by immediate graft dysfunction. Evidence that SCAR contributes to chronic allograft damage (interstitial fibrosis and tubular atrophy) and negatively affects graft outcome is counterbalanced by the scarcity of controlled data proving the beneficial effect of SCAR treatment. The development of sensitive and specific noninvasive methods to monitor the immune status of the graft by using mRNA determinations, gene expression analysis (microarrays), proteomic analysis, and magnetic resonance spectroscopy, can help to ultimately replace protocol biopsies and also contribute to the further unraveling of the complex underlying immunological mechanisms responsible for SCAR. The latter would enable clinicians to preemptively make strategic adjustments to immunosuppressive therapy in an attempt to further improve renal allograft survival and clinical care of the transplant patient.