Cytokine gene polymorphism in kidney transplantation--impact of TGF-beta 1, TNF-alpha and IL-6 on graft outcome

Chronic allograft nephropathy (CAN) is one of the main causes of graft loss in renal transplantation. Polymorphisms with functional significance in the promoter and coding regions of cytokine genes have been suggested as a possible factor for graft rejection. The aim of this study was to investigate the impact of cytokine gene polymorphism of pro and anti-inflammatory cytokines on development of CAN in a group of renal transplant patients and donors. Eight single nucleotide polymorphisms (SNPs) including TNFA (-308), TGFB1 (cdns10, 25), IL-10 (-1082, -819, -592), IL-6 (-174) and IFNG (+874) were analyzed in 56 patients with stable graft function (SGF), 10 with CAN and 28 kidney donors by PCR-SSP method. CAN was significantly associated with the recipient TGFB1 cod10 T/T and combination of cods10, 25 T/T G/G genotypes (high producer), (p<0.05). Influence of patient's TNFA genotype correlated with high level of gene expression on the development of CAN was further demonstrated when the patients were stratified according to the HLA mismatches (HLA-DRB MMs). Additionally donor TNFA-308 G/A (high) and IL-6-174 CC (low) genotypes were increased in cases with CAN. No statistically significant differences in distribution of IL-10, IL-6 and IFNG genotypes between recipients with SGF and CAN were found. In conclusion our data suggest that the high producer genotype of profibrogenetic TGF-beta1, pro-inflammatory TNF-alpha and genetically determined low production of immunoregulatory IL-6 cytokine might be risk factors for CAN development.