Donor cytokine gene polymorphisms are associated with increased graft loss and dysfunction after transplant

Association of C-509T and T869C polymorphisms of transforming growth factor-beta1 gene with chronic allograft nephropathy and graft survival in Korean renal transplant recipients

PURPOSE

Transforming growth factor-beta1 (TGF-beta1) has been associated with the promotion of renal allograft interstitial fibrosis and thereby chronic allograft nephropathy (CAN). The literature on TGF-beta1 polymorphisms and their importance in graft survival and CAN is not conclusive.

METHODS

TGF-beta1 gene polymorphisms (C-509T and T869C) were examined in a group of 207 Korean renal transplant recipients using real-time polymerase chain reaction assays. The CAN group (n = 18) was defined by a typical biopsy confirming CAN or chronic calcineurin inhibitor nephrotoxicity. The rest of the patients were classified into the No CAN group (n = 189).

RESULTS

No significant differences were observed in the genotype distributions of both C-509T and T869 polymorphisms between the two groups. Allele frequencies and age-, sex-, HLA mismatch-adjusted odds ratio of each genotype as assessed by logistic regression analysis were also not significantly different between the two groups. Linkage disequilibrium coefficients between polymorphisms indicated that investigated polymorphisms of TGF-beta1 (D' = 0.98) were in tight linkage. However, there were no significant differences in the frequencies of the reconstructed haplotypes between the two groups. Kaplan-Meier method and log-rank tests did not indicate any statistically significant effects of TGF-beta1 gene polymorphisms on graft survival.

CONCLUSION

TGF-beta1 gene polymorphisms (C-509T, T869C) are not significantly associated with an increased risk of development of CAN and graft survival in Korean renal transplant recipients.

Donor genomics influence graft events: the effect of donor polymorphisms on acute rejection and chronic allograft nephropathy

BACKGROUND

Organs procured from deceased donors emanate from individuals with diverse genetic backgrounds. Donor organs, therefore, may vary in their response to injury and immune stimuli in a genetically determined manner. We assessed polymorphisms from 244 renal allograft donors to better understand the impact of donor polymorphisms on selected transplant outcomes.

METHODS

Donor genomic DNA restriction fragment length polymorphisms were assayed for evidence of common cytokine [interleukin (IL)-2, IL-6, IL-10, tumor necrosis factor (TNF)-alpha, TGF-beta, interferon (IFN)-gamma] and chemokine (CCR2, CCR5) polymorphisms. Associations between donor polymorphisms and graft events were determined using chi-square, linear regression, and Kaplan-Meier analyses.

RESULTS

Several genotypic polymorphisms demonstrated a modest association with acute rejection, including the transforming growth factor (TGF)-beta T/C codon 10 (P= 0.027) and the CCR5 G/A 59029 (P= 0.039) genes by chi-square analysis. Notably, the presence of the T allele in the IFN-gamma gene (+874) demonstrated a highly significant association with biopsy-proven chronic allograft nephropathy (P < 0.008). This association remained highly significant in a multiple linear regression model that incorporated biopsy-proven acute rejection as a covariate.

CONCLUSION

These data suggest that many of the donor polymorphisms studied in this analysis may influence a recipient's immune response to a renal allograft. However, their greatest impact may be demonstrated in long-term outcomes.

Polymorphisms in immunoregulatory genes: towards individualized immunosuppressive therapy?

In organ transplantation, successful immunosuppression requires that both rejection and infection episodes be minimized. Unfortunately it is currently impossible to predict individual dose requirement for immunosuppressive drugs, but a number of studies of various immune response genes are now being performed with a view to identifying genotypes associated with rejection and/or infection. The key role of cytokines in the immune response and other processes, including fibrosis, has concentrated most of this attention on polymorphisms in cytokine genes. Data on polymorphisms in genes encoding tumor necrosis factor-alpha, transforming growth factor-beta, interferon-gamma and interleukin (IL)-1, 4, 6 and 10 together with the IL-4 receptor have been analyzed but so far there is currently no indication of any consistently positive associations between graft rejection and any of these polymorphisms. Studies of other immunomodulatory genes including the CTLA4 gene and the chemokine receptor CCR-5 have proved more positive though the data, so far, are only preliminary. In conclusion, additional large series studies of these and other cytokine genes, as well as other immunoregulatory gene polymorphisms of proven functional significance are needed to achieve major progress in this area.