SOCS3 and IRS-1 gene expression differs between genotype 1 and genotype 2 hepatitis C virus-infected HepG2 cells.

BACKGROUND: The poor response to antiviral treatment of hepatitis C virus (HCV)-infected patients with genotype 1b has been associated with a higher prevalence of metabolic syndrome. However, the molecular link between these clinical entities is not clear. The goal of this study was to clarify the role of genotype 1b and 2 in the genetic expression of suppressor of cytokine signaling 3 (SOCS3) and insulin receptor substrate 1 (IRS-1). METHODS: We infected human hepatocellular carcinoma cell line (HepG2) cells with human HCV genotype 1b or 2 and measured the gene and protein expression of SOCS3 at various times. We also evaluated impairment in the insulin pathway by analysis of IRS-1 and phospho-AKT. For the control, we used HepG2 cell cultures treated with non-infectious serum. We also demonstrated the occurrence of HCV infection by the detection of both positive and negative strands in the cells and culture medium. To test infection of the HepG2 cells, we performed quantitative real-time polymerase chain reaction (qRT-PCR) of viral load at different time points. We analyzed the viral genotype in the pellet and supernatant. RESULTS: At each time point, we found positive and negative strands in the infected cells, while in the medium we found positive, but no negative strands. We also detected the presence of the correct genotype in the medium. Two weeks following infection when the viral load was higher, we tested genotype 1b and 2 infected cells. SOCS3 gene expression was significantly higher in genotype 1b-infected cells (median 2.56; mean 2.82+/-0.59) compared with genotype 2 (median 1.34; mean 1.46+/-0.31) (p=0.04) and control cells (median 1.09; mean 1.02+/-0.11, p=0.02). There was no difference between cells exposed to genotype 2 and control cells. Conversely, IRS-1 was significantly lower in genotype 1b-infected cells (median 15.97; mean 15.45+/-0.67) compared with genotype 2-infected cells (median 16.45; mean 16.44+/-0.01, p=0.04). Statistically significant differences were seen when comparing the pAKT/AKT ratio in genotype 1b-infected cells (0.19+/-0.034) and not genotype 1b-infected (genotype 2-infected and non-infected) cells (0.253+/-0.004, p=0.03). This inverse regulation is compatible with interactions between the molecular expression of SOCS3, IRS-1 and phospho-AKT mediated by the genotype 1b virus. CONCLUSIONS: Up-regulation of the SOCS3 gene might be one of the mechanisms governing non-response to therapy and expression of insulin resistance mediated via a direct mechanism at this level of genotype 1b HCV.

Clinical expression of insulin resistance in hepatitis C and B virus-related chronic hepatitis: differences and similarities.

AIM: To investigate the prevalence of the clinical parameters of insulin resistance and diabetes in patients affected by chronic hepatitis C (CHC) or chronic hepatitis B (CHB). METHODS: We retrospectively evaluated 852 consecutive patients (726 CHC and 126 CHB) who had undergone liver biopsy. We recorded age, sex, ALT, type 2 diabetes and/or metabolic syndrome (MS), body mass index (BMI), and apparent disease duration (ADD). RESULTS: Age, ADD, BMI, prevalence of MS and diabetes in patients with mild/moderate liver fibrosis were significantly higher in CHC. However, the degree of steatosis and liver fibrosis evaluated in liver biopsies did not differ between CHC and CHB patients. At multivariate analysis, age, sex, BMI, ALT and diabetes were independent risk factors for liver fibrosis in CHC, whereas only age was related to liver fibrosis in CHB. We also evaluated the association between significant steatosis (>30%) and age, sex, BMI, diabetes, MS and liver fibrosis. Diabetes, BMI and liver fibrosis were associated with steatosis >30% in CHC, whereas only age and BMI were related to steatosis in CHB. CONCLUSION: These data may indicate that hepatitis C virus infection is a risk factor for insulin resistance.

Suppressor of cytokine signaling 3 (SOCS3) expression and hepatitis C virus-related chronic hepatitis: Insulin resistance and response to antiviral therapy.

UNLABELLED: The response to antiviral therapy is lower in hepatitis C virus (HCV) patients with genotype 1 than in those with genotype 2. Overexpression of the suppressor of cytokine signaling 3 (SOCS3) gene in liver tissue is associated with a poorer treatment outcome in patients with chronic hepatitis C viral genotype 1. Also, insulin resistance has been implicated in nonresponse to an anti-HCV treatment. To understand why HCV genotype 1 patients respond differently, we investigated SOCS3 gene expression, metabolic syndrome (MS), and the response to therapy in a cohort of patients with HCV-related hepatitis. A total of 198 patients (108 with genotype 1 and 90 with genotype 2) treated with pegylated interferon plus ribavirin were consecutively enrolled in the study. We measured SOCS3 expression in Epstein-Barr virus-transformed lymphoblastoid cell lines derived from peripheral lymphocytes of a subset of 130 patients. MS was more frequent in genotype 1 patients than in genotype 2 patients (P < 0.01). Nonresponders (P < 0.01), MS (P < 0.001), and genotype 1 (P < 0.001) were significantly related to SOCS3 overexpression. However, SOCS3 levels were higher in nonresponders also, regardless of the genotype (P < 0.01). In a univariate analysis, the genotype (P < 0.001), age (P < 0.001), SOCS3 (P < 0.001), and MS (P < 0.001) were significantly related to the response to therapy. However, in a multivariate analysis, SOCS3 was the only independent predictor of the response (odds ratio = 6.7; P < 0.005). CONCLUSION: We speculate that SOCS3 expression per se may influence the response to antiviral therapy and that the genotype 1b virus might induce its up-regulation. This may account for the different responses to therapy between genotype 1-infected and genotype 2-infected patients.