Analysis of transforming growth factor-β1 gene polymorphisms in patients with Hepatitis C infection

Considerable attention is focused on polymorphisms in the TGF-β1 gene, a multifunctional cytokine that is a potential susceptibility and modifier gene of organ fibrosis, cancer, autoimmune and inflammatory diseases, keloid disease, and hypertrophic scarring. Recently, we described novel LightCycler-based methods facilitating the examination of the three known variants (Leu10Pro, Arg25Pro, Thr263Ile) in the coding region of the human TGF-β1 gene (TGFB1) and found that the presence of Pro either in codon 25 or 10 is associated with the inter-individual variability in developing more severe hepatic fibrosis during chronic HCV infection (Tag et al. (2003) Cytokine 24:173–81; Wang et al. (2005) WJG 11:1929–36). In addition, a recent report has associated codon 10 CC and the TGFB1 promoter (-509) variation with the severity of lung disease (Drumm et al. (2005) NEJM 353:1443–53). Liver needle biopsies from approximately 400 patients suffering from chronic HCV infection were scored for the necroinflammatory activity (grade) and degree of hepatic fibrosis (stage). The genotypes at codon 10, 25, 263, and position -509 were determined. To do so we optimized protocols allowing the isolation of genomic DNA from respective paraffin sections and introduced novel high-throughput LightCycler-genotyping methodologies for respective allele variants. The determined genotypes were correlated to the grade and stage of hepatic injury. In the chosen collective we have reproduced our previous findings suggesting that the presence of Pro either in codon 25 or 10 is associated with the inter-individual variability in developing more severe fibrosis during chronic HCV infection. We found no correlation of necroinflammatory activity and allelic variations suggesting that the stage of hepatic fibrosis rather than the grade is predetermined by the presence of Pro at codon 25 in patients suffering from chronic HCV infection. Patients being CT or TT at position -509 had a lower risk to evolve severe fibrosis than patients being CC at that site confirming the hypothesis that variations in the secretory signal sequence and TGFB1 promoter may contribute to the genetic susceptibility of HCV-induced hepatic fibrosis.

Acknowledgment: Supported by the Network of Competence in Medicine Hep-Net.