TNF-alpha IFN-gamma IL-6, IL-10, and TGF-beta1 gene polymorphisms in renal allografts

The imbalance between Tregs, Th17 cells and inflammatory cytokines among renal transplant recipients

Background

A significant barrier to organ transplantation is the cellular rejection that occurs and mediated by antibodies, T cells, and innate immune cells. This study was aimed to determine the number of CD4⁺CD25⁺Foxp3⁺ Treg, CD4⁺IFN-γ⁻IL-17⁺ Th17, CD4⁺IFN-γ⁺IL-17⁻ Th1 and CD4⁺IFN-γ⁺IL-17⁺ Th1/17 cells in renal transplant recipients (RTR).

Methods

Renal transplantation was performed for a total of 35 patients with end-stage renal failure. The number of CD4⁺CD25⁺Foxp3⁺ Treg, CD4⁺IFN-γ⁻IL-17⁺ Th17, CD4⁺IFN-γ⁺IL-17⁻ Th1 and CD4⁺IFN-γ⁺IL-17⁺ Th1/17 cells, and the serum level of IFN-γ, TNF-α, IL-2, IL-4, IL-6, IL-10, and IL-17 were measured in pre- and post-transplant patients and 10 healthy controls (HC) using flow cytometry and Cytometric Bead Array (CBA). The association between the number of different subsets of CD4⁺ T-cells and clinical parameters were analyzed among the pre- and post-transplant patients, and the healthy controls.

Results

The number of CD4⁺IFN-γ⁻IL-17⁺ Th17, CD4⁺IFN-γ⁺IL-17⁻ Th1 and CD4⁺IFN-γ⁺IL-17⁺ Th1/17 cells were significantly increased in patients with End-Stage Renal Failure (ESRF) compared to the HC. Stratification analysis indicated that AMR (Acute antibody mediated acute rejection), AR (acute rejection) and CR (chronic rejection) groups displayed greater number of CD4⁺IFN-γ⁻IL-17⁺ Th17, CD4⁺IFN-γ⁺IL-17⁻ Th1 and CD4⁺IFN-γ⁺IL-17⁺ Th1/17 cells as well as high level of serum IL-2, IFN-γ, TNF-α and IL-17. But, the AMR, AR and CR groups have shown lower level of CD4⁺CD25⁺Foxp3⁺ T cells and serum IL-10 compared to transplant stable (TS) patients. Moreover, the number of Tregs were negatively correlated with the number of Th17 cells in RTR patients. The number of Tregs and Th17 cells were positively correlated with the eGFR and serum creatinine values, respectively.

Conclusion

The imbalance between different types of CD4⁺ T cells and dysregulated inflammatory cytokines may contribute towards renal transplantation rejection.

Imbalance of different types of CD4(+)Foxp3(+) T cells in renal transplant recipients

AIMS

To determine the number of CD4(+)CD25(-)Foxp3(+), CD4(+)CD25(+)Foxp3(+) and CD4(+)CXCR5(+)Foxp3(+) T cells in renal transplant recipients that are transplanted stable (TS), or experiencing accelerated rejection (ALR), or acute rejection (AR).

METHODS

Renal transplantation was conducted in 28 patients with end-stage renal failure (ESRF). The number of peripheral CD4(+)CD25(-)Foxp3(+), CD4(+)CD25(+)Foxp3(+), or CD4(+)CXCR5(+)Foxp3(+) T cells and the serum levels of interleukin-10 (IL-10) were measured in pre- and post-transplant patients and these results were compared to 10 healthy controls (HC). Correlation between CD4(+)CD25(+)Foxp3(+) and estimated glomerular filtration rate (eGFR), CD4(+)CD25(-)Foxp3(+) and serum creatinine (Cr) levels, or Cr and IL-10 levels in TS patients was also determined.

RESULTS

The number of CD4(+)CD25(-)Foxp3(+) T cells was significantly increased in patients with ESRF, as compared to HC. Stratification analysis demonstrated that TS patients contained greater numbers of CD4(+)CD25(+)Foxp3(+) and CD4(+)CXCR5(+)Foxp3(+) T cells, higher levels of serum IL-10, and fewer numbers of CD4(+)CD25(-)Foxp3(+) T cells than ESRF patients. In contrast, ALR and AR patients contained fewer numbers of CD4(+)CD25(+)Foxp3(+) and CD4(+)CXCR5(+)Foxp3(+) T cells, greater numbers of CD4(+)CD25(-)Foxp3(+) T cells, and lower levels of serum IL-10 than ESRF patients. In TS patients, the numbers of CD4(+)CD25(+)Foxp3(+) and CD4(+)CD25(-)Foxp3(+) T cells were positively correlated with eGFR and serum Cr levels, respectively.

CONCLUSION

An imbalance of different types of CD4(+)Foxp3(+) T cells might be involved in renal transplant rejection.

Association between IL-6 -174G/C polymorphism and acute rejection of renal allograft: evidence from a meta-analysis

BACKGROUND

Results from published studies on the association of donor or recipient IL-6 -174G/C (rs1800795) polymorphism with acute rejection (AR) of renal allograft are conflicting. We performed a meta-analysis to estimate the possible association.

METHODS

Studies were identified by searching PUBMED and EMBASE until July 1, 2011. Meta-analysis was performed in a fixed/random effects model using Revman 5.0.25 and STATA10.0.

RESULTS

Seven studies addressing the association between donor high producer genotype (G/G and G/C) of IL-6 -174G/C polymorphism and acute rejection of renal allograft were identified. Pooled OR based on 341 cases (whose recipient developed acute rejection) and 702 controls (whose recipient did not develop acute rejection) was 0.59 (95% CI, 0.26-1.33; p=0.20), with a strong between-study heterogeneity. No association was observed in the subgroup analysis based on ethnicity. 13 studies evaluating the association between recipient IL-6 -174G/C polymorphism and acute rejection were identified. Pooled OR based on 451 cases (patients did not develop acute rejection) and 848 controls was 1.00 (95% CI=0.72-1.37; p=0.98), with a weak between-study heterogeneity.

CONCLUSIONS

Donor high producer genotype (G/G and G/C) of IL-6 -174G/C polymorphism had a tendency of decreased risk for acute rejection, although it was not statistically significant. Recipient high producer genotype was not associated with acute rejection of renal allograft. Additional well designed studies with larger sample size are needed to support our findings, especially for the association between donor high producer genotype (G/G and G/C) of IL-6 -174G/C polymorphism and acute renal allograft rejection.

Association of pro/anti-inflammatory cytokine gene variants in renal transplant patients with allograft outcome and cyclosporine immunosuppressant levels

T-helper (Th) type 1/Th2 cytokines are key mediators in induction/effecter phases of all immune and inflammatory responses playing role in acute/chronic renal allograft rejection. Association studies lead to identification of patient risk profiles enabling individualization of level of immunosuppressions. We investigated the association of allograft rejection with interleukin-2 (IL-2), IL-4, IL-6, tumor necrosis factor-α (TNF-α) −308, transforming growth factor-β (TGF-β) (C-del, codon 10 and 25) gene variants in 184 renal transplant recipients and 180 controls. These cytokine genotypes were also evaluated with cyclosporine levels (C2) at one month in 135 stable recipients. High producing genotypes B1B1 of IL-4 and AA of TNF-α α308 showed significant association with rejection of allograft. The dose-adjusted C2 levels were significantly lower in patients with the high producing genotype T/T of IL-2 and heterozygous G/C of TGF-β codon 25 (P = 0.012 and 0.010, respectively). Haplotype frequencies were comparable in subjects for TGF-β codon-10 and 25. Combined inter-gene interaction showed high risk for rejection in recipients with high producing genotype B1B1 of IL-4 and AA of TNF-α and high TNF-α (AA) with low TGF-β (CC or Pro/Pro). In conclusion, association of IL-4 VNTR and TNF-α −308 suggested the involvement of these cytokines contributing to pathogenesis of allograft rejection. Recipients with TT genotype of IL-2 and GC of TGF-β codon 25 having low C2 levels may require higher cyclosporine dosage. Combined analysis of gene-gene interaction demonstrated synergistic effect of cytokines increasing risk for rejection. Thus, this information may help in pre-assessment of allograft outcome and to optimize cyclosporine therapy in post-transplant patients.

Functions of TNF and its receptors in renal disease: distinct roles in inflammatory tissue injury and immune regulation

Tumor necrosis factor (TNF) alpha is a potent proinflammatory cytokine and important mediator of inflammatory tissue damage. In addition, it has important immune-regulatory functions. Many experimental studies and clinical observations support a role for TNF in the pathogenesis of acute and chronic renal disease. However, given its dual functions in inflammation and immune regulation, TNF may mediate both proinflammatory as well as immunosuppressive effects, particularly in chronic kidney diseases and systemic autoimmunity. Blockade of TNF in human rheumatoid arthritis or Crohn's disease led to the development of autoantibodies, lupus-like syndrome, and glomerulonephritis in some patients. These data raise concern about using TNF-blocking therapies in renal disease because the kidney may be especially vulnerable to the manifestation of autoimmune processes. Interestingly, recent experimental evidence suggests distinct roles for the 2 TNF receptors in mediating local inflammatory injury in the kidney and systemic immune-regulatory functions. In this review the biologic properties of TNF and its receptors, TNF receptors 1 and 2, relevant to kidney disease are summarized followed by a review of the available experimental and clinical data on the pathogenic role of the TNF system in nonimmune and immune renal diseases. Experimental evidence also is reviewed that supports a rationale for specifically blocking TNF receptor 2 versus anti-TNF therapies in some nephropathies, including immune complex-mediated glomerulonephritis.

Renal Allograft Immune Response Is Influenced by Patient and Donor Cytokine Genotypes

This study investigated the impact of specific cytokine genotypes on the incidence of acute rejection episodes (ARE), chronic graft dysfunction (CGD), and anti-HLA donor-specific antibody (DS-Ab) production in 86 renal transplant recipients and 70 cadaveric donors. A PCR-SSP method was performed for the analysis of polymorphisms in TNF-alpha, IL-6, TGF-beta, IL-10, and IFN-gamma cytokines. DS-Ab monitoring of sera was performed using a FCXM analysis. Observed cytokine frequencies for patients and donors were not significantly different from the expected frequencies under Hardy-Weinberg equilibrium conditions. The evaluation in recipients revealed a higher frequency of DS-Ab-positive patients among the TNF-alpha high (50.0% vs 25.7%), and for the IL-10 cytokine a greater incidence of ARE-positive patients (35.8% vs 18.2%) with the high + intermediate, compared with the low genotype. The combined effect of these 2 genotypes predisposed to DS-Abs (71.4% vs 25.3%; P = 0.02; odds ratio [OR] = 7.37). As for the TGF-beta1 cytokine, we observed a higher number of CGD-positive patients among high compared with intermediate producers (14.3% vs 0%; P = .050). The analysis of donors revealed a significantly lower incidence of ARE-positive patients among recipients whose donors were carriers of the high IL-6 G/G-genotype compared with the G/C+C/C-genotypes (16.7% vs 41.2%; P = .03), suggesting a protective effect of the G/G genotype on ARE and a predisposing role of donor (-174)allele C. In addition, we noted an association between the IFN-gamma low A/A-genotype and a higher incidence of ARE (42.1% vs 0%; P = .002) and DS-Ab production (47.4% vs 12.5%; P = .02) compared with high producers.

Effects of pentoxifylline on the cytokines that may play a role in rejection and resistive index in renal transplant recipients

Pentoxifylline (PTX) is a nonselective phosphodiesterase inhibitor that inhibits the production of TNFalpha and IL6 and IL-10 cytokines. In renal rejection TNFalpha, IL-6, and IL-10 may have important roles. In this study, 22 renal transplant recipients treated with tacrolimus, prednisolone, and mycophenolate mofetil were prescribed PTX (2 x 600 mg/d) for 3 months (GI), and 20 similar patients not receiving PTX were used as controls (GII). Stable subjects whose serum creatinine was lower than 1.8 mg/dL and were more than 6 months posttransplant, were enrolled into this study if the blood pressure was well controlled and there was no diabetes mellitus, infection, or inflammation. At the end of 3 months TNF-alpha decreased from 4.2 +/- 2.1 to 2.4 +/- 0.7 (P = .001) and 4.0 +/- 2.2 to 3.9 +/- 1.7 (P = .718), IL-10 also decreased from 3.90 +/- 1.9 to 2.38 +/- 0.6 (P = .001) and 4.02 +/- 1.6 to 3.82 +/- 1.5 (P = .225) in GI and GII, respectively. For IL-10 and TNF-alpha the alterations between baseline and the last visit of GI and GII were significant (P < .002 for all). Resistive index (RI) decreased in GI but the difference in alterations between baseline and the last visit of GI and GII was marginal. In summary IL-10 and TNF-alpha levels decreased in stable recipients treated with PTx. RI also decreased marginally secondary to PTx treatment. PTx was well tolerated and free side effects. PTx did not affect tacrolimus levels or other biochemical and hematological parameters.

Immune Response Gene Polymorphisms in Renal Transplant Recipients

BACKGROUND

T-cell activation and regulation are under genetic control and vary between individuals. However, the influence of functional immune response gene polymorphisms on transplant outcomes remains controversial.

METHODS

A case-control design compared 100 white renal transplant recipients with or without acute graft rejection during the first year posttransplant and 50 normal controls. The polymorphic frequencies of the T-cell signaling genes CD45, CD40L and CTLA-4, and the cytokine genes TNF-alpha, IFN-gamma, IL-10 and TGF-beta1 were studied. The primary analysis examined rejection risk, and subsidiary analyses graft failure and patient death.

RESULTS

Multivariate analysis showed no significant association between acute rejection and single nucleotide polymorphisms in CTLA-4, TGF-beta1, IL-10 or TNF-alpha genes or dinucleotide repeat polymorphisms in IFN-gamma and CD40L genes. Allele CD40L-147 was associated with reduced graft failure (P=0.004), and TGFb-25pro with increased graft failure (P=0.0007), although the latter showed a bidirectional dose effect. There was no significant association between patient death and any polymorphisms in the genes examined. The variant (G) allele of the CD45 gene was not detected in the study population. Minor differences in carriage rates observed by univariate analysis did not predict graft or patient outcome in multivariate analysis.

CONCLUSION

The primary analysis demonstrated no significant association between the immune response gene polymorphisms examined and acute renal graft rejection in Caucasian patients receiving triple immunosuppression. Subsidiary analyses suggesting an influence of CD40L and TGFbeta1 genes on graft survival require independent confirmation.

Effect of Cytokines and Chemokines (TGF-β, TNF-α, IL-6, IL-10, MCP-1, RANTES) Gene Polymorphisms in Kidney Recipients on Posttransplantation Outcome: Influence of Donor-Recipient Match

Posttransplantation alloantigen-dependent and alloantigen-independent processes are both mediated by cytokines and chemokines. Recently cytokines and chemokines, as well as their receptors, have been shown to be highly polymorphic. The cytokine and chemokine gene polymorphisms are associated with variable production, activity, expression, or ligand-receptor affinity. The aim of our study was to analyze the relation between selected cytokine and chemokine gene polymorphisms in kidney donors and recipients as a function of donor-recipient match and posttransplantation outcome. Polymorphisms transforming growth factor-beta (TGF-beta); tumor necrosis factor-alpha (TNF-alpha); interleukin (IL)-6, and IL-10; monocyte chemoattractant protein-1 (MCP-1); and RANTES (regulated upon activation, normal T-cell expressed and secreted) genes were determined using DNA polymerase chain reaction technology in 268 healthy volunteers, 345 kidney transplant recipients (1997 to 1999), and 298 cadaveric donors. Patients were followed up for 4 to 6 years. The distribution of alleles of selected genes was identical in control subjects, cadaveric donors, and recipients. Low TGF-beta production in both the donor and recipient genotypes was associated with risk for early rejection (6 months) and worse graft function at 4 years. The only tendency for worse graft outcome was observed among donor-recipient combinations mismatched for TGF-beta genotype. Genetic determination of TNF-alpha and IL-10 production was associated with delayed graft function and rejection. IL-6 gene polymorphisms had no effect on the incidence of early acute rejections, but was associated with worse 5-year outcomes. Determinations of MCP-1 overproduction and RANTES-109 TT allele were associated with significant deterioration of graft function. Our data support the hypothesis that the strength of the alloimmune response after transplantation is in part genetically determined. Donor-recipient matching of cytokine gene polymorphisms has a marginal effect.

Relevance of IL10, TGFbeta1, TNFalpha, and IL4Ralpha gene polymorphisms in kidney transplantation: a collaborative transplant study report

Single nucleotide polymorphisms (SNPs) of cytokine genes have been shown to influence cytokine plasma levels. Cytokines are important mediators during organ graft rejection. It was reported that certain cytokine genotypes are associated with improved kidney graft survival. In the present study, SNPs within the IL10 promoter gene, the first exon of the TGFbeta1 gene, the TNFalpha promoter gene, and the IL4Ralpha gene were analyzed in 2298 first and 1901 repeat cadaver kidney recipients. We found no significant effect on the survival rate of first grafts. Among retransplants, we observed that recipients who were homozygous for the high TNFalpha producer genotype -308 A had a significantly lower graft survival rate than patients who were carriers of the low producer genotype -308 G (at 3 years: 63.0% vs. 79.5%; pcorrected = 0.0116). The results of this large-scale study suggest that IL10, TGFbeta1, TNFalpha, and IL4Ralpha cytokine genotypes do not affect the survival of primary kidney grafts. The outcome of retransplants appears to be affected by TNFalpha genotypes only.

The interleukin-6 -174promoter polymorphism is associated with long-term kidney allograft survival

BACKGROUND

Th1-dependent effector mechanisms may be responsible for allograft rejection. Recently, interleukin-6 (IL-6) has been shown to antagonize CD4+ T cells to effector Th2 cells and, in the process, differentiate them into Th1 cells.

METHODS

To assess the role of IL-6 in long-term allograft survival, 158 patients after first cadaveric kidney transplantation were analyzed for the biallelic -174G-->C promoter polymorphism of the IL-6 gene.

RESULTS

Carriers of the -174C-allele (genotype GC/CC) had an inferior three-year graft survival (71/104 = 68.3%; P = 0.0059) with a 3.7-fold increased relative risk of graft loss compared to carriers of the -174GG-genotype (48/54 = 88.9%). The -174GC/CC-genotype retained its negative impact on graft survival when other established prognostic factors and further cytokine polymorphisms (-308TNF-alpha, TGF-beta1 codon 10 & 25, -592/-819/-1082IL-10 and +874IFN-gamma) were considered simultaneously.

CONCLUSIONS

Since the clinical impact on transplant outcome seems as important as matching for histocompatibility antigens, genotyping of the IL-6 -174polymorphism may offer a new method for identifying patients at increased risk of allograft loss.

Frequency of cytokine polymorphisms in populations from western Europe, Africa, Asia, the Middle East and South America

PCR-SSOP identification procedures for IL-2, IL-6, IL-10, TNF-alpha and TNF-beta cytokine polymorphisms have been developed. Application of the procedures to a range of diverse geographically distributed populations has identified ethnic differences within the groups studied. Five populations were investigated, Northern Ireland, South African Zulu, Omani, Singapore Chinese and Mexican Mestizos.

No association between transforming growth factor beta gene polymorphism and acute allograft rejection after cardiac transplantation

Transforming growth factor-beta1 (TGF-beta1) is a multifunctional cytokine, which inhibits both development of Th1 and Th2 subsets and the Th1 proinflammatory response. TGF-beta1 production is influenced through several single nucleotide polymorphisms (SNP) in the structural gene and promoter region. Acute rejection of transplants depends on the Th1/Th2 balance within the graft, high levels of TGF-beta1 shift this balance towards Th2. We investigated whether genotypes of 4 SNP (-800 and -509 in the promoter region, codon 10 and codon 25 in the first exon) were correlated with cardiac disease or with incidence of rejection after heart transplantation (HTX). Genotypes were determined for 70 HTX patients and 61 donors by sequencing or oligonucleotide ligation assay. No association between SNP genotypes and heart disease or acute transplant rejection was observed. We conclude that genetic variation in the TGF-beta1 gene neither influences the existence of cardiomyopathy nor the incidence of rejection upon HTX.