Insulin resistance is associated with steatosis in nondiabetic patients with genotype 1 chronic hepatitis C

High molecular weight form of adiponectin levels of Japanese patients with chronic hepatitis C virus infection

AIM

The aim of the present study was to clarify the correlation between serum adiponectin level and the properties of hepatitis C virus (HCV).

METHODS

A meal test was carried out for insulin resistance assessment in 81 patients with chronic HCV infection. Blood samples were taken before and after the test to measure serum insulin and plasma glucose (PG). The adiponectin level was measured by enzyme-linked immunosorbent assay in each patient.

RESULTS

Serum adiponectin levels were significantly correlated with the area under the insulin curve (AUC-insulin)during the meal test and with serum HCV-RNA level. Multiple regression analysis showed age to be a significant independent parameter associated with an increased adiponectin level, whereas male sex, fasting insulin, and serum HCV-RNA level were significant independent parameters associated with a decreased adiponectin level.

CONCLUSION

It is possible that insulin resistance in patients with chronic HCV infection is related to adiponectin secretion.

Hepatic steatosis in HIV-HCV coinfected patients in France: comparison with HCV monoinfected patients matched for body mass index and HCV genotype

BACKGROUND

Significance of steatosis in HIV-HCV coinfection remains controversial.

AIM

To compare the prevalence and predictors of hepatic steatosis between HIV-HCV and HCV patients matched for steatosis known determinants.

METHODS

A total of 564 HCV-naive patients undergoing liver biopsy were studied: 137 with HIV-HCV coinfection and 427 with HCV monoinfection, among whom 137 were matched for age, gender, body mass index and HCV genotype.

RESULTS

Steatosis of any grade (67.1% vs. 41.6%, P < 0.0001), mixed steatosis (55.4% vs. 21.1%, P < 0.0001), severe histological activity (A2-A3: 78.1% vs. 55.5%, P < 0.0001) and severe fibrosis (F3-F4: 33.1% vs. 15.3%, P < 0.0001) were significantly more common in coinfected than in matched monoinfected patients. In multivariate analysis, steatosis was associated only with severe histological activity [odds ratio (OR): 3.1 (95% CI: 1.3-7.1)] in coinfected patients and with elevated body mass index [OR; 1.3 (1.1-1.5)], HCV genotype 3 [OR: 5.6 (2.3-13.9)], severe histological activity [OR: 3.1 (1.3-7.3)] and severe fibrosis [OR: 4.7 (1.3-17.3)] in monoinfected patients.

CONCLUSIONS

Steatosis is significantly more common and severe in HIV-HCV coinfected than in HCV monoinfected French patients, even after matching for body mass index and HCV genotype. Steatosis is associated only with severe histological activity in coinfected patients and with previously reported factors in monoinfected patients, thus suggesting different underlying mechanisms.

Hepatic steatosis in chronic hepatitis B develops due to host metabolic factors: a comparative approach with genotype 1 chronic hepatitis C

BACKGROUND/AIMS

Hepatic steatosis has not been adequately studied in chronic hepatitis B, while it is considered to be a cardinal feature in chronic hepatitis C and to be mainly metabolically induced in patients infected with genotype 1. We investigated the prevalence of and the parameters associated with steatosis in HBeAg-negative chronic hepatitis B.

METHODS

We studied 213 patients with HBeAg-negative chronic hepatitis B and compared them with 163 patients with genotype-1 chronic hepatitis C. Steatosis was semi-quantitatively graded.

RESULTS

Steatosis was significantly less frequent in chronic hepatitis B than chronic hepatitis C (60% versus 72%, P=0.016), but there was no difference in the prevalence of moderate/severe steatosis. In chronic hepatitis B, steatosis was associated only with higher body mass index (P=0.002), while moderate/severe steatosis was associated only with higher body mass index (P=0.043) and diabetes (P=0.031). Steatosis was relatively less frequent in chronic hepatitis B than chronic hepatitis C non-diabetic, normal-weight patients (45.6% versus 62.5%, P=0.063), but it did not differ in diabetic and/or overweight/obese patients with chronic hepatitis B or chronic hepatitis C.

CONCLUSIONS

Hepatic steatosis in HBeAg-negative chronic hepatitis B (a) is less frequent than in genotype-1 chronic hepatitis C, (b) is mainly associated with presence of host metabolic factors, such as high body mass index and diabetes and (c) does not seem to be associated with the severity of liver histological lesions.

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

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.

Correlation of serum adiponectin levels and hepatic steatosis in hepatitis C virus genotype 1 infection

Steatosis is an important cofactor in hepatitis C virus (HCV) because it is associated with fibrosis and reduces early and sustained virologic response. Recent studies suggest that HCV genotype 1 is not steatogenic if additional risk factors are not present. Because hypoadiponectinemia was found to be a feature of nonalcoholic steatohepatitis (NASH) independent of insulin resistance, its level in patients with hepatitis C genotype can reveal the optimal therapeutic strategy. This study was conducted to determine the role of the relationship between steatosis and serum adiponectin levels in the progression of liver damage in HCV genotype 1 without known risk factors for NASH. Patients (n=50) with biopsy-proven chronic hepatitis C (CHC), positive HCV RNA, and raised alanine aminotransferase were enrolled. They were carefully selected to rule out possible confounding factors for the presence of steatosis and additional systemic or liver disease. Associations between serum adiponectin levels and grade of steatosis, histologic activity index (HAI), fibrosis grade of liver biopsies, patient age, HCV viral load, and serum transaminase activities were studied. Also, adiponectin levels were compared with those of a control group of 30 healthy volunteers with normal ultrasound findings of the upper abdomen who had no known NASH risk factors. The investigators found that adiponectin levels in patients with CHC genotype 1 were similar to those in healthy subjects. No significant association was found between adiponectin levels and severity of steatosis, HCV RNA levels, HAI, transaminases, and fibrosis. Steatosis was present in 41 patients (82%) with CHC. Multivariate analysis of data on 50 patients revealed that severity of steatosis was independently related to age alone (P=.03). A correlation between HCV RNA load and HAI was observed (P=.02; r=0.712). HAI also was associated with stage of fibrosis (P=.00; r= 0.612). In cases of chronic HCV genotype 1 hepatitis, steatosis is a common histologic feature, although no risk factors are known. Results presented here cannot establish an association between adiponectin and severity of steatosis when risk factors for steatosis are unknown. Additional studies are needed to discover a metabolic treatment that would seek to improve the progression of hepatic steatosis in CHC infection.

Glucose intolerance and hypoadiponectinemia are already present in lean patients with chronic hepatitis C infected with genotype non-3 viruses

OBJECTIVES

Steatosis and metabolic abnormalities seem to be frequent and deleterious in chronic hepatitis C. Changes in glucose homeostasis and in adiponectin levels, an adipokine with anti-inflammatory and insulin-sensitive properties, were evaluated in patients with chronic hepatitis C according to steatosis, liver fibrosis and body mass index.

METHODS

Seventy-three patients with chronic hepatitis C (40 men, 33 women) infected with genotypes non-3 and 22 healthy controls (11 men and 11 women) were included in the study and all had a biochemical evaluation, including metabolic parameters, adiponectin measurement, and a liver biopsy. Insulin sensitivity was assessed with the HOMA 1-IR insulin resistance model.

RESULTS

Steatosis was found in 65.7% of the patients and significant fibrosis (METAVIR F2-F4) was present in 28.7%. The presence of steatosis could only be predicted by fibrosis, whereas significant fibrosis could be predicted by steatosis and age. Adiponectin levels were significantly decreased (-32%) with the severity of the steatosis. Although overweight chronic hepatitis C patients (body mass index>or=25 kg/m2) had insulin resistance and hypoadiponectinemia, lean chronic hepatitis C patients (body mass index<25 kg/m2) had already significantly higher glycemia and lower adiponectin levels than in controls.

CONCLUSIONS

This study confirms the high incidence of steatosis in patients infected by hepatitis C virus genotypes non-3, well linked to the development of fibrosis and metabolic abnormalities. Importantly, the present findings put emphasis on the early development of these metabolic abnormalities as they were already found in lean patients with chronic hepatitis C. The direct implication of hepatitis C virus is thus further stressed in the development of steatosis and insulin resistance, with or without involvement of host factors.

Insulin resistance and liver injury in hepatitis C is not associated with virus-specific changes in adipocytokines

The role of tumor necrosis factor alpha, interleukin 6, leptin, and adiponectin in the pathogenesis of hepatitis C virus (HCV)-associated insulin resistance (IR) remains controversial. We tested the hypothesis that these adipocytokines contribute to chronic HCV-associated IR and liver injury by first comparing their serum levels and homeostasis model assessment of insulin resistance (HOMA-IR) in 154 untreated, non-diabetic, HCV-infected male subjects with fibrosis stage 0-2, to that in 75 healthy volunteers matched for age, body mass index (BMI), and waist-hip ratio (WHR). We next examined whether the adipocytokine levels were associated with the extent of hepatic steatosis, portal/periportal inflammation and fibrosis in our total cohort of 240 HCV-infected male subjects. Significantly higher levels of HOMA-IR (2.12 versus 1.63, P = 0.01), TNFalpha (1.28 versus 0.60 pg/ml, P < 0.001) and IL6 (2.42 versus 1.15 pg/ml, P = 0.001) were noted in the HCV cohort compared with healthy controls respectively, but there were no significant differences in leptin and adiponectin concentrations. By multiple linear regression, independent predictors of HOMA-IR included the body mass index, and the serum levels of leptin (positive correlation) and adiponectin (negative correlation), but not that of TNFalpha and IL6. Only TNFalpha levels were correlated with the extent of histological injury (portal/periportal inflammation, P = 0.02).

CONCLUSION

Whereas leptin and adiponectin contribute to IR, none of the adipocytokines accounted for the elevated IR in HCV-infected subjects. The adipocytokines were not associated with histological features of chronic HCV infection except for TNFalpha which correlated with portal/periportal inflammation. HCV-associated IR is most likely an adipocytokine-independent effect of the virus to modulate insulin sensitivity.

The impact of insulin resistance, serum adipocytokines and visceral obesity on steatosis and fibrosis in patients with chronic hepatitis C

AIMS

To assess whether host metabolic factors influence the degree of hepatic steatosis and fibrosis in patients infected with hepatitis C virus, and to evaluate the impact of anti-viral therapy on insulin resistance and serum levels of adipocytokines.

METHODS

Clinical and biochemical features, anthropometrical characteristics, and levels of fasting insulin, leptin, adiponectin and resistin were measured in 'naïve' patients with chronic hepatitis C, before, during and after therapy with Peg-Interferon-alpha 2a plus Ribavirin.

RESULTS

Forty-eight patients were included (M/F 28/20; mean age 50.0 +/- 12.6 years; 62.5% genotype-1). Body mass index was 26.4 +/- 4.0 kg/m(2), and visceral obesity was present in 24 patients. At multivariate analysis (RR; 95% CI), steatosis was associated to older age (1.08; 1-1.18), necroinflammatory activity (17.67; 1.6-194.46), and raised insulin levels (1.39; 1.1-1.77). Fibrosis was related to necroinflammatory activity (25.73; 2.54-261.11), and steatosis (6.47; 1.09-38.29). Sustained viral response was achieved by 62.5% of patients and was associated with younger age (0.92; 0.85-0.99), genotype non-1 (10.61; 1.52-73.76) and absence of visceral obesity (13.78; 2.36-80.29). At the end of follow-up, insulin and the homeostasis model assessment for insulin resistance were reduced and adiponectin increased when compared with baseline, all unrelated to the outcome of treatment.

CONCLUSIONS

Visceral obesity correlates with the degree of steatosis and fibrosis, and it negatively affects treatment response. Significant changes of insulin resistance and adipocytokines occur under treatment, irrespective of virological outcome.

A growing burden: the pathogenesis, investigation and management of non-alcoholic fatty liver disease

Non-alcoholic fatty liver disease (NAFLD) is the most common hepatic disorder in western countries, and its incidence is increasing. This review outlines the significant health burden posed by NAFLD and discusses what is presently known about its pathogenesis, including the roles of the metabolic syndrome, obesity, insulin resistance, hepatic steatosis, reactive oxygen species, inflammatory cytokines and adipocytokines. The way in which NAFLD is clinically diagnosed is described, and areas of uncertainty surrounding its investigation are identified, before discussing the relative merits of the limited treatment options available and looking ahead to potential therapeutic strategies for the future.

Liver transplantation for HCV cirrhosis: improved survival in recent years and increased severity of recurrent disease in female recipients: results of a long term retrospective study

In recent years, a worsening outcome of hepatitis C virus (HCV)-positive recipients and a faster progression of recurrent disease to overt cirrhosis has been reported. Our aims were to 1) assess patient survival and development of severe recurrent disease (Ishak fibrosis score > 3) in different transplant years; and 2) model the effects of pre- and post-liver transplantation (LT) variables on the severity of recurrent disease. A multicenter retrospective analysis was conducted on 502 consecutive HCV-positive transplant recipients between January 1990 and December 2002. Protocol liver biopsies were obtained at 1, 3, 5, 7, and 10 yr post-LT in almost 90% of the patients. All 502 patients were included in the overall survival analysis, while only the 354 patients with a follow-up longer than 1 yr were considered for the analysis of predictors of disease progression. The overall Kaplan-Meier survival rates were 78.7%, 66.3%, and 58.6%, at 12, 60, and 120 months, respectively, and a trend for a better patient survival over the years emerged from all 3 centers. The cumulative probability of developing HCV-related recurrent severe fibrosis (Ishak score 4-6) in the cohort of 354 patients who survived at least 1 yr remained unchanged over the years. Multivariate analysis indicated that older donors (P = 0.0001) and female gender of recipient (P = 0.02) were the 2 major risk factors for the development of severe recurrent disease, while the adoption of antilymphocytic preparations was associated with a less aggressive course (P = 0.03). Two of these prognostic factors, donor age and recipient gender, are easily available before LT and their combination showed an important synergy, such that a female recipient not only had a much higher probability of severe recurrent disease than a male recipient but her risk increased with the increasing age of the donor, reaching almost 100% when the age of the donor was 60 or older. In conclusion, a trend for a better patient survival was observed in more recent years but the cumulative probability of developing severe recurrent disease remained unchanged. The combination of a female recipient receiving an older graft emerged as a strong risk factor for a severe recurrence.

Hepatic steatosis in genotype 4 chronic hepatitis C is mainly because of metabolic factors

BACKGROUND/AIM

Hepatic steatosis is considered to be mostly associated with viral factors in genotype 3 and metabolic factors in genotype 1 chronic hepatitis C, while there are rather few data for genotype 4. We determined the parameters associated with steatosis in 350 chronic hepatitis C patients, focusing on genotype 4.

METHODS

Histological lesions were evaluated according to Ishak's classification and steatosis was semiquantitatively graded. Several patient characteristics on the biopsy day were also evaluated.

RESULTS

Steatosis was present in 73% of patients without significant differences among genotypes. Moderate/severe steatosis was more frequent in genotype 3 than 4 (44% vs 26%, P= 0.025) and similar between genotype 4 and 1 patients. Moderate/severe steatosis was associated with body mass index (BMI) in genotype 4 (P= 0.023) and gamma-glutamyl-transpeptidase in genotype 3 patients (P= 0.044). In 150 nondiabetic patients with BMI < or =25 kg/m(2), moderate/severe steatosis was present in 15, 40, and 11% of genotype 1, 3, and 4 patients, respectively, (P= 0.005) and was independently associated only with genotype 3. In multivariate analysis, steatosis grade or moderate/severe steatosis was independently associated with higher BMI, genotype 3, and lower cholesterol.

CONCLUSIONS

Moderate or severe steatosis is significantly less frequent in genotype 4 than 3 chronic hepatitis C patients and similar between genotype 4 and 1. In nondiabetic, nonoverweight patients, moderate or severe steatosis is present in only 10-15% of genotype 4 or 1 compared with 40% of genotype 3 patients. Thus, hepatic steatosis in genotype 4 is mostly associated with metabolic factors, similar to those in genotype 1.

Steatosis as a cofactor in other liver diseases: hepatitis C virus, alcohol, hemochromatosis, and others

As obesity prevalence rises, there is evidence that fatty liver disease can act synergistically with other chronic liver diseases to aggravate parenchymal injury. This is characterized best in chronic hepatitis C, where steatosis is caused by viral and metabolic effects. There is evidence that steatosis and its metabolic abnormalities also exacerbate other diseases, such as alcoholic liver disease, hemochromatosis, and, possibly, drug-induced liver disease. The pathogenesis seems related to increased susceptibility of steatotic hepatocytes to apoptosis, enhanced oxidative injury, and altered hepatocytic regeneration. Data suggest that active management of obesity may improve liver injury and decrease the progression of fibrosis in patients who have other chronic liver diseases.

Non-alcoholic steatohepatitis in children

Non-alcoholic steatohepatitis (NASH) is an important liver disease in children; it can cause cirrhosis in children. The disease mechanism involves hepatic insulin resistance with hyperinsulinemia and changes in certain adipocytokines and inflammatory mediators. The differential diagnosis of childhood NASH includes metabolic disorders, drug hepatotoxicity, and alcoholic hepatitis in adolescent patients. The histologic features in childhood NASH often differ from those in adults who have NASH. Treatment is gradual weight loss through changes in food intake patterns and increased levels of physical activity; the role of drug treatment of NASH in children is an area of ongoing research.

Hepatic steatosis in hepatitis C: comparison of diabetic and nondiabetic patients in the hepatitis C antiviral long-term treatment against cirrhosis trial

BACKGROUND & AIMS

Hepatic steatosis often is observed in patients with chronic hepatitis C and has been reported to be associated with hepatic fibrosis and impaired treatment response in some studies. Our aim was to determine the prevalence of and risk factors for hepatic steatosis among Hepatitis C Antiviral Long-term Treatment against Cirrhosis patients, and to determine the relationship between steatosis, fibrosis, and sustained virologic response (SVR) to re-treatment with pegylated interferon and ribavirin.

METHODS

Baseline data from 1143 Hepatitis C Antiviral Long-term Treatment against Cirrhosis patients, with a mean body mass index of 30, 5% with genotype 3, 38% with cirrhosis, and 24% with diabetes were analyzed.

RESULTS

Steatosis scores of 0, 1, 2, 3, and 4 were observed in 19%, 42%, 30%, 8%, and 1% of patients, respectively. High body mass index, triglyceride and alanine aminotransferase levels, and genotype 3 were associated with higher grades of steatosis. Among nondiabetic patients, steatosis scores of 0-2 but not scores of 3-4 were associated significantly with cirrhosis. For diabetic patients, there was no association between steatosis and cirrhosis. Similarly, steatosis scores of 2-4 were associated with a lack of SVR among nondiabetic but not among diabetic patients.

CONCLUSIONS

In this cohort with predominantly hepatitis C virus genotype 1 infection, steatosis was associated strongly with metabolic factors that contribute to nonalcoholic fatty liver disease. Steatosis correlated with increasing stages of fibrosis up to but not including cirrhosis. Steatosis had a negative impact on SVR among nondiabetic but not diabetic patients. The discordant findings between nondiabetic and diabetic patients indicate that these 2 groups should be considered separately when analyzing metabolic factors and liver disease outcomes.

Race, insulin resistance and hepatic steatosis in chronic hepatitis C

Hepatic steatosis is common in chronic hepatitis C and has been linked to concurrent obesity, insulin resistance, diabetes, disease severity, and poor response to therapy. Racial differences in rates of obesity and diabetes may contribute to racial differences in hepatic steatosis and treatment response. The aim of the present study was to compare hepatic steatosis and its associations between African American (AA) and Caucasian American (CA) patients with chronic hepatitis C, genotype 1, participating in a prospective study of peginterferon and ribavirin therapy. Liver biopsy results were available from 194 AA patients and 205 CA patients. The 2 groups were compared for anthropometric, clinical, and biochemical features and insulin resistance estimated by the homeostasis model assessment index (HOMA-IR). Sixty-one percent of the AA patients and 65% of the CA patients had hepatic steatosis (P = 0.38). In univariable analysis, steatosis was associated with HOMA-IR, body mass index, waist circumference, serum triglycerides, aminotransferase level, and histological scores for inflammation and fibrosis. After adjusting for these features, AA patients had a lower risk of steatosis than did CA patients (OR 0.54, 95% CI 0.32-0.91, P = 0.02). Insulin resistance but not steatosis was associated with a lower rate of sustained virological response when adjusted for known factors that predict response (relative risk 0.87, 95% CI 0.77-0.99, P = 0.028).

CONCLUSION

After adjusting for the higher prevalence of features associated with hepatic steatosis, AA patients had a lower prevalence of hepatic steatosis than did CA patients with chronic hepatitis C, genotype 1. Insulin resistance but not steatosis was independently associated with lower sustained virological response.

Diabetes and liver disease: an ominous association

Diabetes mellitus and advanced liver disease are associated with each other more frequently than expected by chance, and such an association carries a significant risk of morbidity and mortality. A metabolic pathway leading to advanced liver disease via fatty liver and steatohepatitis has been demonstrated, further supporting the possibility that cirrhosis may be a late complication of diabetes. In addition, an interaction between hepatitis C virus (HCV) and insulin resistance increases the overall prevalence of associated diseases, through largely unidentified mechanisms. Extensive prospective monitoring of non-alcoholic fatty liver disease cases, analysis of insulin signaling in HCV-infected patients using molecular biology techniques, and intervention studies, will help to clarify the mechanisms of action of the possible clinical strategies, the predictive value of biochemical, histological, and clinical markers, and the effectiveness of treatments available.

Fibrosis in genotype 3 chronic hepatitis C and nonalcoholic fatty liver disease: Role of insulin resistance and hepatic steatosis

Hepatic steatosis has been associated with fibrosis, but it is unknown whether the latter is independent of the etiology of fat infiltration. We analyzed the relationship between clinical characteristics, insulin resistance (HOMA-R) and histological parameters in 132 patients with "viral" steatosis caused by genotype 3 chronic hepatitis C (CHC-3) and 132 patients with "metabolic" steatosis caused by nonalcoholic fatty liver disease (NAFLD), matched by age, BMI, and degree of liver fat accumulation. Tests of liver function were comparable in the two study populations. The prevalence of features of insulin resistance was higher in NAFLD, as was HOMA-R (P = .008). Logistic regression analysis confirmed that steatosis was associated with a high viral load and low serum cholesterol in CHC-3, and with high aminotransferase, glucose, ferritin and hypertriglyceridemia in NAFLD. At univariate analysis, advanced fibrosis was associated with steatosis in NAFLD, but not in CHC-3. Other parameters related to fibrosis severity were HOMA-R and a low platelet count in CHC-3, and high aminotransferases, HOMA-R, ferritin and low HDL-cholesterol in NAFLD. On multivariate analysis, only low platelet count (OR = 0.78; 95% CI, 0.67-0.92) and HOMA-R (OR = 2.98; 1.13-7.89) were independent predictors of advanced fibrosis in CHC-3. In NAFLD, severe fibrosis was predicted by fat grading (OR = 3.03; 1.41-6.53), ferritin (OR = 1.13; 1.03-1.25) and HOMA-R (OR = 1.16; 1.02-1.31). In conclusion, insulin resistance is an independent predictor of advanced fibrosis in both NAFLD and CHC-3, but the extent of steatosis contributes to advanced disease only in NAFLD. Virus-induced hepatic steatosis as seen in CHC-3 does not contribute significantly to liver fibrosis.

Insulin resistance and hepatitis C

Insulin resistance is the major feature of the metabolic syndrome and depends on insulin secretion and insulin sensitivity. In chronic hepatitis C, insulin resistance and type 2 diabetes mellitus are more often seen than in healthy controls or chronic hepatitis B patients. Hepatitis C virus (HCV) infection promotes insulin resistance, mainly by increased TNF production together with enhancement of suppressor of cytokine (SOC-3); both events block PI3K and Akt phosphorylation. Two types of insulin resistance could be found in chronic hepatitis C patients: “viral” and “metabolic” insulin resistance. Insulin resistance in chronic hepatitis C is relevant because it promotes steatosis and fibrosis. The mechanisms by which insulin resistance promotes fibrosis progression include: (1) steatosis, (2) hyperleptinemia, (3) increased TNF production, (4) impaired expression of PPARγ receptors. Lastly, insulin resistance has been found as a common denominator in patients difficult-to-treat like cirrhotics, overweight, HIV coinfected and Afro-American. Insulin resistance together with fibrosis and genotype has been found to be independently associated with impaired response rate to peginterferon plus ribavirin. Indeed, in genotype 1, the sustained response rate was twice (60%) in patients with HOMA ≤ 2 than patients with HOMA > 2. In experiments carried out on Huh-7 cells transfected by full length HCVRNA, interferon alpha blocks HCV replication. However, when insulin (at doses of 128 μU/mL, similar that seen in the hyperinsulinemic state) was added to interferon, the ability to block HCV replication disappeared, and the PKR synthesis was abolished. In summary, hepatitis C promotes insulin resistance and insulin resistance induces interferon resistance, steatosis and fibrosis progression.

Impact of obesity on treatment of chronic hepatitis C

Obesity and the metabolic syndrome have hepatic manifestations, including steatosis and progression of fibrosis. In individuals with chronic hepatitis C, obesity is associated with inflammation, insulin resistance, steatosis, progression of fibrosis, and nonresponse to treatment with interferon or peginterferon alpha and ribavirin. Patients with both hepatitis C and obesity-related nonalcoholic fatty liver disease are at greater risk for more advanced liver disease. We review the mechanisms by which obesity may be associated with decreased efficacy of interferon-based therapies in individuals with chronic hepatitis C and the therapeutic strategies that may increase the effectiveness of these therapies in obese individuals.