IL28B polymorphism as a predictor of antiviral response in chronic hepatitis C

To evaluate the effect of single nucleotide polymorphisms of interleukin (IL)-28B, rs12979860 on progression and treatment response in chronic hepatitis C.

Patients (n = 64; 37 men, 27 women; mean age, 44 ± 12 years) with chronic hepatitis C, genotype 1, received treatment with peg-interferon plus ribavirin. Genotyping of rs12979860 was performed on peripheral blood DNA. Histopathological assessment of necroinflammatory grade and fibrosis stage were scored using the METAVIR system on a liver biopsy sample before treatment. Serum viral load, aminotransferase activity, and insulin level were measured. Insulin resistance index, body mass index, waist/hip ratio, percentage of body fat and fibrosis progression rate were calculated. Applied dose of interferon and ribavirin, platelet and neutrophil count and hemoglobin level were measured.

A sustained virological response (SVR) was significantly associated with IL28B polymorphism (CC vs TT allele: odds ratio (OR), 25; CC vs CT allele: OR, 5.4), inflammation activity (G < 1 vs G > 1: OR, 3.9), fibrosis (F < 1 vs F > 1: OR, 5.9), platelet count (> 200 × 10(9)/L vs < 200 × 10(9)/L: OR, 4.7; OR in patients with genotype CT: 12.8), fatty liver (absence vs presence of steatosis: OR, 4.8), insulin resistance index (< 2.5 vs > 2.5: OR, 3.9), and baseline HCV viral load (< 10(6) IU/mL vs > 10(6) IU/mL: OR, 3.0). There was no association with age, sex, aminotransferases activity, body mass index, waist/hip ratio, or percentage body fat. There was borderline significance (P = 0.064) of increased fibrosis in patients with the TT allele, and no differences in the insulin resistance index between groups of patients with CC, CT and TT alleles (P = 0.12). Spearman's rank correlation coefficient between insulin resistance and stage of fibrosis and body mass index was r = 0.618 and r = 0.605, respectively (P < 0.001). Significant differences were found in the insulin resistance index (P = 0.01) between patients with and without steatosis. Patients with the CT allele and absence of a SVR had a higher incidence of requiring threshold dose reduction of interferon (P = 0.07).

IL28B variation is the strongest host factor not related to insulin resistance that determines outcome of antiviral therapy. Baseline platelet count predicts the outcome of antiviral therapy in CT allele patients.