No abstract

The role of tumor necrosis factor ␣, 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 HCVinfected male subjects. Significantly higher levels of HOMA-IR (2.12 versus 1.63, P ‫؍‬ 0.01), TNF␣ (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. C hronic hepatitis C virus (HCV) infection is associated with the development of hepatic steatosis 1-5 and unique, virus-specific alterations in host metabolism leading to the development of insulin resistance (IR) and type 2 diabetes mellitus (T2DM). [6][7][8][9] We and others have shown that chronic HCV infection is associated with the development of IR in the absence of overt T2DM, irrespective of the presence or absence of cirrhosis. 6,10 Further, IR as assessed by the homeostasis model (HOMA-IR) 11 was independently associated with virally-mediated portal inflammation and an increased rate of fibrosis progression, indicating that IR is a cause rather than a consequence of hepatic fibrosis in HCV infection. 6 Despite recent recognition of the important role of IR in the progression of liver injury in HCV infection [12][13][14] and the response to antiviral therapy, 12,14,15 the mechanism of HCV-induced IR is not known. There is an abundance of literature to suggest that adipose tissue-derived cytokines (adipocytokines) may play a key role in the development of obesity-related IR. 16,17 TNF␣, IL6 and leptin are proinflammatory cytokines that can directly alter glucose and lipid metabolism. [16][17][18] In contrast, adiponectin, the most abundant of all the adipocytokines has an opposite effect, increasing insulin sensitivity [16][17][18] and having anti-steatotic, 19 anti-inflammatory 20 and antifibrotic effects. 21 In nonalcoholic fatty liver disease, it has been shown that serum levels of the various adipocyto-

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 HDLcholesterol 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. (HEPATOLOGY 2006;44:1648-1655