HDL cholesterol protects from liver injury in mice with intestinal specific LXRα activation

Background and aims: Liver X receptors (LXRs) exert anti-inflammatory effects even though their hepatic activation is associated with hypertriglyceridemia and hepatic steatosis. Selective induction of LXRs in the gut might provide protective signal(s) in the aberrant wound healing response that induces fibrosis during chronic liver injury, without hypertriglyceridemic and steatogenic effects. Methods: Mice with intestinal constitutive LXRα activation (iVP16-LXRα) were exposed to intraperitoneal injection of carbon tetrachloride (CCl4) for 8 weeks, and in vitro cell models were used to evaluate the beneficial effect of high-density lipoproteins (HDL). Results: After CCl4 treatment, the iVP16-LXRα phenotype showed reduced M1 macrophage infiltration, increased expression M2 macrophage markers, and lower expression of hepatic pro-inflammatory genes. This anti-inflammatory effect in the liver was also associated with decreased expression of hepatic oxidative stress genes and reduced expression of fibrosis markers. iVP16-LXRα exhibited increased reverse cholesterol transport in the gut by ABCA1 expression and consequent enhancement of the levels of circulating HDL and their receptor SRB1 in the liver. No hepatic steatosis development was observed in iVP16-LXRα. In vitro, HDL induced a shift from M1 to M2 phenotype of LPS-stimulated Kupffer cells, decreased TNFα-induced oxidative stress in hepatocytes and reduced NF-kB activity in both cells. SRB1 silencing reduced TNFα gene expression in LPS-stimulated KCs, and NOX-1 and IL-6 in HepG2. Conclusions: Intestinal activation of LXRα modulates hepatic response to injury by increasing circulating HDL levels and SRB1 expression in the liver, thus suggesting this circuit as potential actionable pathway for therapy

HCC development is associated to peripheral insulin resistance in a mouse model of NASH

NAFLD is the most common liver disease worldwide but it is the potential evolution to NASH and eventually to hepatocellular carcinoma (HCC), even in the absence of cirrhosis, that makes NAFLD of such clinical importance. Aim: we aimed to create a mouse model reproducing the pathological spectrum of NAFLD and to investigate the role of possible co-factors in promoting HCC. Methods: mice were treated with a choline-deficient L-amino-acid-defined-diet (CDAA) or its control (CSAA diet) and subjected to a low-dose i.p. injection of CCl 4 or vehicle. Insulin resistance was measured by the euglycemic-hyperinsulinemic clamp method. Steatosis, fibrosis and HCC were evaluated by histological and molecular analysis. Results: CDAA-treated mice showed peripheral insulin resistance at 1 month. At 1-3 months, extensive steatosis and fibrosis were observed in CDAA and CDAA+CCl4 groups. At 6 months, equal increase in steatosis and fibrosis was observed between the two groups, together with the appearance of tumor. At 9 months of treatment, the 100% of CDAA+ CCl4 treated mice revealed tumor versus 40% of CDAA mice. Insulin-like Growth Factor-2 (IGF-2) and Osteopontin (SPP-1) were increased in CDAA mice versus CSAA. Furthermore, Immunostaining for p-AKT, p-c-Myc and Glypican-3 revealed increased positivity in the tumors. Conclusions: the CDAA model promotes the development of HCC from NAFLD-NASH in the presence of insulin resistance but in the absence of cirrhosis. Since this condition is increasingly recognized in humans, our study provides a model that may help understanding mechanisms of carcinogenesis in NAFLD. © 2014 De Minicis et al

Insulin resistance and necroinflammation drives ductular reaction and epithelial-mesenchymal transition in chronic hepatitis C.

To study the mechanism(s) linking insulin resistance (IR) to hepatic fibrosis and the role of the epithelial component in tissue repair and fibrosis in chronic hepatitis C (CHC).Prospective observational study.Tertiary care academic centre.78 consecutive patients with CHC.IR, calculated by the oral glucose insulin sensitivity during oral glucose tolerance test; necroinflammatory activity and fibrosis, defined according to Ishak's score; steatosis, graded as 0 (66\%). To evaluate the role of the epithelial component in tissue repair and fibrosis, the expansion of the ductular reaction (DR) was calculated by keratin-7 (CK7) morphometry. Nuclear expression of Snail, downregulation of E-cadherin and expression of fibroblast specific protein-1 (FSP1) and vimentin by CK7-positive cells were used as markers of epithelial-mesenchymal transition in DR elements.IR, the degree of necroinflammation and expansion of the DR (stratified as reactive ductular cells (RDCs), hepatic progenitor cells and intermediate hepatobiliary cells according to morphological criteria) were all associated with the stage of fibrosis. Nuclear Snail expression, E-cadherin downregulation and vimentin upregulation were observed in RDCs. By dual immunofluorescence for CK7 and FSP1, the number of RDCs undergoing epithelial-mesenchymal transition progressively increased together with the necroinflammatory score. By multivariate analysis, total inflammation and insulin resistance were the only factors significantly predicting the presence of advanced fibrosis (Ishak score ≥3) and the expansion of RDCs.This study indicates that IR is associated with the degree of necroinflammatory injury in CHC and contributes to hepatic fibrosis by stimulating the expansion of RDCs that express epithelial-mesenchymal transition markers

Post-load insulin resistance does not predict virological response to treatment of chronic hepatitis C patients without the metabolic syndrome.

BACKGROUND AND AIM: The role of insulin resistance in predicting virological response to therapy of chronic hepatitis C is debated. We assessed the association between basal (defined as homeostasis model assessment of insulin resistance (HOMA-IR)>2) and post-load insulin resistance (as oral glucose insulin sensitivity index<9.8 mg/kg/min) with the rapid and sustained virological responses in chronic hepatitis C. METHODS: Observational prospective study of 124 treatment-naïve patients with chronic hepatitis C not fulfilling the metabolic syndrome criteria, adherent to a standard treatment with pegylated interferon alpha plus ribavirin. RESULTS: Insulin resistance was detected in 50% (by HOMA-IR) and 29% (by oral glucose insulin sensitivity index) of patients. Independent predictors of rapid virologic response were hepatitis C virus (HCV) genotype 2 (odds ratio 5.66; 95% confidence interval 1.88-17.01), HCV genotype 3 (odds ratio 5.23; 95% confidence interval 1.84-14.84) and lower basal ferritin levels (odds ratio 0.99; 95% confidence interval 0.993-0.998). Independent predictors of sustained virologic response were HCV genotype 2 (odds ratio 19.54; 95% confidence interval 2.29-166.41) and HCV genotype 3 (odds ratio 3.24; 95% confidence interval 1.10-9.58). Rapid virologic response was by itself predictive of sustained virologic response (odds ratio 40.90; 95% confidence interval 5.37-311.53). CONCLUSIONS:Insulin resistance, measured by both static and dynamic methods, does not predict rapid or sustained virologic response in chronic hepatitis C patients without the metabolic syndrome

Insulin resistance and necroinflammation drives ductular reaction and epithelial-mesenchimal transition in chronic hepatitis C

Objective: To study the mechanism(s) linking insulin resistance (IR) to hepatic fibrosis and the role of the epithelial component in tissue repair and fibrosis in chronic hepatitis C (CHC). Design: Prospective observational study. Setting: Tertiary care academic centre. Patients: 78 consecutive patients with CHC. Main outcome measures: IR, calculated by the oral glucose insulin sensitivity during oral glucose tolerance test; necroinflammatory activity and fibrosis, defined according to Ishak\u2019s score; steatosis, graded as 0 (&lt;5% of hepatocytes), 1 (5e33%), 2 (33e66%) and 3 (>66%). To evaluate the role of the epithelial component in tissue repair and fibrosis, the expansion of the ductular reaction (DR) was calculated by keratin-7 (CK7) morphometry. Nuclear expression of Snail, downregulation of E-cadherin and expression of fibroblast specific protein-1 (FSP1) and vimentin by CK7-positive cells were used as markers of epithelial-mesenchymal transition in DR elements. Results: IR, the degree of necroinflammation and expansion of the DR (stratified as reactive ductular cells (RDCs), hepatic progenitor cells and intermediate hepatobiliary cells according to morphological criteria) were all associated with the stage of fibrosis. Nuclear Snail expression, E-cadherin downregulation and vimentin upregulation were observed in RDCs. By dual immunofluorescence for CK7 and FSP1, the number of RDCs undergoing epithelial-mesenchymal transition progressively increased together with the necroinflammatory score. By multivariate analysis, total inflammation and insulin resistance were the only factors significantly predicting the presence of advanced fibrosis (Ishak score $3) and the expansion of RDCs. Conclusion: This study indicates that IR is associated with the degree of necroinflammatory injury in CHC and contributes to hepatic fibrosis by stimulating the expansion of RDCs that express epithelial-mesenchymal transition markers