Study of transforming growth factor-β1 gene, mRNA, and protein in Japanese renal transplant recipients

Transforming growth factor (TGF)-β1 may contribute to chronic allograft nephropathy and graft loss; however, the exact molecular mechanism remains unclear. Therefore, we assess the relationship between TGF-β1 gene polymorphisms, expression, and development of allograft nephropathy.

We studied 135 renal transplant recipients at our hospital. TGF-β1 gene polymorphisms (codons 10 and 25) were determined from peripheral blood leukocyte DNA. Plasma TGF-β1 mRNA was measured by real-time polymerase chain reaction and TGF-β1 protein levels were assessed by enzyme-linked immunosorbent assay. The relationship between TGF-β1 genotyping, expression, and rejection and results of renal biopsy were evaluated.

The genotype frequency of transplant recipients was 49.6%, 30.4%, and 20.0% for C/T, C/C and T/T at codon 10, 100% for G/G at codon 25, respectively. According to the criteria of Banff '97 classification, 24 cases were classified as acute rejection and whose genotypes were 16, 3, and 5 cases for C/T, C/C and T/T at codon 10. Plasma mRNA expression was elevated in 14 cases and decreased in 8 cases after acute rejection. We measured 267 specimens of TGF-β1 protein and there was no relation between amount of TGF-β1 protein and mRNA.

Our results suggest that the relationship between plasma TGF-β1 expression and the development of allograft nephropathy remains uncertain. Frequency of allograft rejection differ with TGF-β1 codon 10 genotypes and the high-risk genotype was different from the reports of other countries.