TGF-beta1 gene polymorphisms and peritoneal equilibration test results in CAPD patients

Transforming growth factor-beta1 (TGF-beta1) stimulates the expression of collagen mRNA in cultured human peritoneal mesangial cells, which may predispose them to developing peritoneal fibrosis. Polymorphisms in the signal sequence genetically may be responsible for increased TGF-beta1 production (i.e., a substitution at amino acid position 10 and 25, +869 Leu(10)-Pro and +915 Arg(25)-Pro, respectively). The aim of this study was to find out whether there is any relation between peritoneal equilibration test (PET) results and TGF-beta1 gene polymorphism. Thirty-two CAPD patients and 72 healthy subjects were included into the study. Each CAPD patient had undergone two PET with a two-year interval. The patients were classified according to the results of a baseline PET as high (high-high average) and low (low-low average) transporters. In high transporters group (n = 20), the genotype frequencies were found as 45% Leu/Leu, 55% Leu/Pro for codon 10; and 85% Arg/Arg, 15% Arg/Pro for codon 25. In low transporters group (n = 12), the genotype frequencies were detected as 66.7% Leu/Leu and 33.3% Leu/Pro for codon 10; and 83.3% Arg/Arg, 16.7% Arg/Pro for codon 25. The distribution of the TGF-beta1 genotypes in our control population was compatible with a Hardy-Weinberg equilibrium. We found no relation between TGF-beta1 genotypes and peritoneal transport group (chi(2) test, p > 0.5). There was no relation between TGF-beta1 genotype and longitudinal change in peritoneal transport. This study is the first study analyzing the possible link between TGF-betal gene polymorphisms and the characteristics of peritoneal transport and longitudinal change of peritoneal transport characteristics in CAPD patients. Further work is needed to clarify the functional importance of these two polymorphisms in TGF-beta1 production and in the development of peritoneal fibrosis.