The IFN-? and TGF-?1 cytokines perform antagonistic activities in the immune response, and polymorphisms in these genes may induce changes in their plasma levels and influence the course of chronic Hepacivirus C (HCV) infection. The present study evaluated the IFNG +874A/T and TGFB1 -509 C/T polymorphisms in 99 samples from patients with chronic hepatitis C and in 300 samples from healthy donors, and the present study also investigated the association of cytokine plasma level with disease stage. Polymorphisms were identified by real-time PCR, and cytokine levels were measured by enzyme-linked immunosorbent assay. The frequency of the IFNG +874A/T polymorphic allele was not associated with susceptibility to HCV infection, but it was associated with lower inflammatory activity (p = 0.0432). The frequency of the TGFB1 -509C/T polymorphic (TT) genotype was associated with HCV infection (p = 0.0062) and a higher risk of infection (OR = 2.0465; p = 0.0091). Plasma levels of IFN-? were higher in TT genotype carriers among the control (p = 0.0012) and HCV groups (p = 0.0064) as well as in patients with fibrosis (p = 0.0346) and patients with a high degree of inflammatory activity (p = 0.0381). The highest TGF-?1 levels were found in HCV-infected (p = 0.0329) individuals and in TT genotype carriers. Patients with cirrhosis had higher TGF-?1 (p = 0.0400). IFN-? and TGF-?1 levels showed a negative correlation (p = 0.0001). In conclusion, the TGFB1 -509C > T polymorphism is associated with a risk of developing chronic hepatitis C, leading to increased TGF-?1, which inhibits IFN-? production, contributing to the progression to cirrhosis
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