Influence of Cytokine Gene Polymorphisms on Graft Rejection in Turkish Patients with Renal Transplants from Living Related Donors

Relationship Between Angiotensin II Type 1 Receptor Antibody Positivity and Cytokine Gene Polymorphism in Renal Transplant Patients When Organ Rejection Occurs

OBJECTIVES

Kidney transplant remains the gold standard for the treatment of end-stage renal disease. Relationships between the presence of non-HLA antibodies, antibodies to AT1R, and cytokine gene polymorphisms with rejection have recently been shown. We sought to determine whether the presence of antibodies to AT1R and cytokine gene polymorphisms affected the development of rejection in pediatric and adult patients, whether a relationship is present between cytokine polymorphism and level of antibodies to AT1R, and whether their presence can be a biomarker pretransplant.

MATERIALS AND METHODS

Our study included 100 pediatric and adult kidney transplant patients plus 50 healthy controls. Levels of AT1R antibodies (by enzyme-linked immunosorbent assay) and gene polymorphisms of the cytokines transforming growth factor β, tumor necrosis factor α, interleukins 6 and 10, and interferon gamma cytokines (by sequence- specific primer-polymerase chain reaction) were studied retrospectively and evaluated with the SPSS statistical program.

RESULTS

We found no statistically significant relationship between levels of antibodies to AT1R and gene polymorphisms among the studied cytokines in patients with rejection compared with the healthy controls and patients with uneventful courses posttransplant. However, higher levels of antibodies to AT1R were observed in pediatric compared with adult transplant recipients (P < .001). A statistically significant relationship was also observed between transforming growth factor β1 C/C G/C low-release and interleukin 6 G/C high-release gene polymorphism and levels of antibodies to AT1R (P < .001).

CONCLUSIONS

Because we observed that some gene polymorphisms among the studied cytokines may affect AT1R antibody levels, future studies are needed to understand the mechanism of the relationship. In addition, studies with larger groups are required to sufficiently confirm that higher antibody levels are present in pediatric versus adult patients.

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.

No Major Effect of Innate Immune Genetics on Acute Kidney Rejection in the First 2 Weeks Post-Transplantation

Background

Innate immunity contributes to acute rejection after kidney transplantation. Genetic polymorphisms affecting innate immunity may therefore influence patients’ risk of rejection. IL2 -330T > G, IL10 -1082G > A, -819C > T, and -592C > A, and TNF -308G > A are not associated with acute rejection incidence in Caucasian kidney transplant recipients receiving a calcineurin inhibitor, ciclosporin or tacrolimus (TAC). However, other important innate immune genetic polymorphisms have not yet been extensively studied in recipients and donors. In addition, innate immunogenetics have not been investigated in kidney transplant cohorts receiving only TAC as the calcineurin inhibitor.

Objective

To investigate the effect of recipient and donor CASP1, CRP, IL1B, IL2, IL6, IL6R, IL10, MYD88, TGFB, TLR2, TLR4, and TNF genetics on acute kidney rejection in the first 2 weeks post-transplant in TAC-treated kidney transplant recipients.

Methods

This study included 154 kidney transplant recipients and 81 donors successfully genotyped for 17 polymorphisms in these genes. All recipients were under triple immunosuppressant therapy of TAC, mycophenolate mofetil, and prednisolone. Recipient and donor genotype differences in acute rejection incidence within the first 2 weeks post-transplantation were assessed by logistic regression, adjusting for induction therapy, human leukocyte antigen mismatches, kidney transplant number, living donor, and peak panel-reactive antibody scores.

Results

A trend (Cochran-Armitage P = 0.031) of increasing acute rejection incidence was observed from recipient IL6 -6331 T/T (18%) to T/C (25%) to C/C (46%) genotype [C/C versus T/T odds ratio (95% confidence interval) = 6.6 (1.7 to 25.8) (point-wise P = 0.017)]. However, no genotype differences were significant after Bonferroni correction for multiple comparisons.

Conclusions

This study did not detect any statistically significant effects of recipient or donor innate immune genetics on acute rejection incidence in the first 2 weeks post-transplantation. However, the sample size was small, and future larger studies or meta-analyses are required to demonstrate conclusively if innate immune genetics such as IL6 influence the risk of acute rejection after kidney transplantation.

Association of the PPP3CA c.249G>A variant with clinical outcomes of tacrolimus-based therapy in kidney transplant recipients

BACKGROUND

The effects of genetic variants related to the pharmacodynamic mechanisms of immunosuppressive drugs on their therapeutic efficacy and safety have been poorly explored. This study was performed to investigate the influence of the PPP3CA c.249G>A variant on the clinical outcomes of kidney transplant recipients.

PATIENTS AND METHODS

A total of 148 Brazilian patients received tacrolimus (TAC)-based immunosuppressive therapy for 90 days post-kidney transplantation. The PPP3CA rs3730251 (c.249G>A) polymorphism was determined by real-time polymerase chain reaction. Single-nucleotide polymorphism (SNP) data for CYP3A5 rs776746 (CYP3A5*3C; g.6986A>G) were used to eliminate the confounding effects of this variant.

RESULTS

The PPP3CA c.249G>A SNP did not influence early TAC exposure, renal function, or other laboratory parameters, including levels of urea, creatinine, glucose, and lipids, and blood counts. This variant also did not account for the cumulative incidence of biopsy-confirmed acute rejection or delayed graft function. Regarding adverse events, PPP3CA c.249A allele carriers initially had a 3.05-fold increased probability of treatment-induced blood and lymphatic system disorders compared with c.249GG genotype individuals (95% confidence interval: 1.10-8.48, p=0.032). However, this result was not maintained after adjusting for body weight and CYP3A5*3C SNP status (p=0.086).

CONCLUSION

The PPP3CA c.249G>A variant does not influence the clinical outcomes of Brazilian patients in the early phase of TAC-based immunosuppressive regimen.

Genetic association of interleukin-2, interleukin-4, interleukin-6, transforming growth factor-β, tumour necrosis factor-α and blood concentrations of calcineurin inhibitors in Turkish renal transplant patients

Cytokines are essential for the control of the immune response as most of the immunosuppressive drugs target cytokine production or their action. The calcineurin inhibitors (CNIs) cyclosporine (CsA) and tacrolimus are immunosuppressive drugs widely used after renal transplantation to prevent allograft rejection. They are characterized by large interindividual variability in their pharmacokinetics; therefore, monitoring their blood concentrations is important to predict their optimal dosage following transplantation. Calcineurin inhibitors inhibit the phosphatase activity of calcineurin, thereby suppressing the production of other cytokines such as transforming growth factor (TGF-β), tumour necrosis factor-α (TNF-α), interleukin (IL)-6, IL-2, and IL-4. The aim of this study was to investigate the relationship between polymorphisms of cytokines and blood concentrations of CNIs in renal transplant patients. The study included 53 CsA-treated renal transplant patients and 37 tacrolimus-treated renal transplant patients. Cytokine polymorphisms were analysed using polymerase chain reaction (PCR) sequence-specific primers with the cytokine CTS-PCR-sequence-specific primers Tray Kit; University of Heidelberg. Blood concentrations of CNIs were determined with Cloned Enzyme Donor Immunoassay (CEDIA) method. Patients with TC genotype of TGF-β at codon 10 had lower CsA blood concentrations than the TT and CC genotypes (P = 0.005) at 1 month in CsA treatment group. The ratio of blood concentration/dose of CsA for patients with TGF-β1-codon 10 TC genotype was lower than for patients with TT, CC genotypes, and the dose given to these patients was higher in the first month (P = 0.046). The ratio of blood concentration/dose of CsA for patients with IL-2-330 GG genotype was higher than for patients with GT, TT genotypes, and the dose given to these patients was lower at first month and sixth months (P = 0.043, P = 0.035 respectively). The tacrolimus blood concentrations were significantly higher in patients with the genotype GG of IL-2-330 (P = 0.012) at the third month. Patients who had the TC genotype TGF-β codon 10 had lower CsA blood concentrations and this group had higher acute rejection (P = 0.033). These results suggest that the genotyping for TGF-β-codon 10, IL-2-330 and IL-6-174 polymorphisms may help individualized immunosuppressive dosage regiments.

Combined effects of TGFB1 +869 T/C and +915 G/C polymorphisms on acute rejection risk in solid organ transplant recipients: a systematic review and meta-analysis

Background

Transforming growth factor-beta 1(TGF-β1) is involved in the development of acute rejection (AR) episodes in solid organ transplant recipients; and a number of studies have been conducted to investigate the combined effects of human TGF-β1 gene (TGFB1) +869 T/C and +915 G/C polymorphisms on AR risk. However, the results obtained are inconclusive.

Methods

Eligible studies that investigated the haplotypic association between TGFB1 +869 T/C and +915 G/C polymorphisms and AR risk were comprehensively searched in the PUBMED, EMBASE, China National Knowledge Infrastructure, and Wanfang Database. Statistical analyses were performed by using STATA 12.0 and Review Manager 5.0.

Results

Fourteen eligible studies with 565 AR cases and 1219 non-AR cases were included. Overall, a significantly decreased risk was detected in patients carried with intermediate producer (IP) haplotypes (T/C G/C, T/T G/C, and C/C G/G) and/or low producer (LP) haplotypes (C/C G/C, C/C C/C, T/T C/C, and T/C C/C) compared with high producer (HP) haplotypes (T/T G/G and T/C G/G; IP vs. HP: OR = 0.75, 95% CI, 0.58–0.96, P _{heterogeneity}  = 0.238; IP/LP vs. HP: OR  = 0.77, 95% CI, 0.61–0.98, P _{heterogeneity}  = 0.144). In addition, subgroup analysis by transplant types demonstrated a similar association in patients receiving heart transplant (IP vs. HP: OR  = 0.32, 95% CI, 0.14–0.73, P _{heterogeneity}  = 0.790; IP/LP vs. HP: OR  = 0.41, 95% CI, 0.20–0.85, P _{heterogeneity}  = 0.320).

Conclusions

The current meta-analysis and systematic review indicated that recipient TGFB1 HP haplotypes were significantly associated with an increased risk for AR in solid organ transplant recipients, particularly patients receiving cardiac allograft.

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.