Interleukin-6 (-174G>C) promoter polymorphism in patients infected by hepatitis B virus

Objective: Hepatitis B virus (HBV) infection is one of the most important health problems in the world. Interleukin-6 (IL-6) has been shown to be a major inflammatory cytokine, inducing cell proliferation and expression of acute response genes, such as fibrinogen and C-reactive protein in hepatocytes. IL-6 levels are elevated in patients acutely infected with HBV and have been associated with progression of infection to chronic hepatitis. Methods: In the present study, the role of IL-6 (-174G/C) polymorphism was investigated on individuals which are diagnosed as hepatitis B virus carrier (n=19), chronic hepatitis (n=10) and cirrhosis (n=13), and non-infected individuals with HBV (n=8). In order to determine IL-6 polymorphism, the polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) method was applied using genomic DNA extracted from paraffin embedded liver needle biopsy specimens. Results: The genotype frequencies in 50 samples were observed as follows: 76% homozygote typical (GG), 22% heterozygote (GC) and 2% homozygote atypical (CC). In this study, limited statistical association was observed between IL-6 polymorphism (GG, GC and CC genotype) and chronic hepatitis/cirrhosis compared to hepatitis B virus carriers and non-infected individuals with HBV (p=0.045). Conclusion: As observed in only one patient with chronic hepatitis, IL-6 (-174C/C) genotype is very rare in this study group. Because of lower frequency of -174C/C phenotype, studies in larger series can give statistically more precise conclusions.