Cell metabolism-based therapy for liver fibrosis, repair, and hepatocellular carcinoma.

Progression of chronic liver injury to fibrosis, abnormal liver regeneration, and HCC is driven by a dysregulated dialog between epithelial cells and their microenvironment, in particular immune, fibroblasts, and endothelial cells. There is currently no antifibrogenic therapy, and drug treatment of HCC is limited to tyrosine kinase inhibitors and immunotherapy targeting the tumor microenvironment. Metabolic reprogramming of epithelial and nonparenchymal cells is critical at each stage of disease progression, suggesting that targeting specific metabolic pathways could constitute an interesting therapeutic approach. In this review, we discuss how modulating intrinsic metabolism of key effector liver cells might disrupt the pathogenic sequence from chronic liver injury to fibrosis/cirrhosis, regeneration, and HCC.

Integrative study of diet-induced mouse models of NAFLD identifies PPARα as a sexually dimorphic drug target.

OBJECTIVE: We evaluated the influence of sex on the pathophysiology of non-alcoholic fatty liver disease (NAFLD). We investigated diet-induced phenotypic responses to define sex-specific regulation between healthy liver and NAFLD to identify influential pathways in different preclinical murine models and their relevance in humans. DESIGN: Different models of diet-induced NAFLD (high-fat diet, choline-deficient high-fat diet, Western diet or Western diet supplemented with fructose and glucose in drinking water) were compared with a control diet in male and female mice. We performed metabolic phenotyping, including plasma biochemistry and liver histology, untargeted large-scale approaches (liver metabolome, lipidome and transcriptome), gene expression profiling and network analysis to identify sex-specific pathways in the mouse liver. RESULTS: The different diets induced sex-specific responses that illustrated an increased susceptibility to NAFLD in male mice. The most severe lipid accumulation and inflammation/fibrosis occurred in males receiving the high-fat diet and Western diet, respectively. Sex-biased hepatic gene signatures were identified for these different dietary challenges. The peroxisome proliferator-activated receptor α (PPARα) co-expression network was identified as sexually dimorphic, and in vivo experiments in mice demonstrated that hepatocyte PPARα determines a sex-specific response to fasting and treatment with pemafibrate, a selective PPARα agonist. Liver molecular signatures in humans also provided evidence of sexually dimorphic gene expression profiles and the sex-specific co-expression network for PPARα. CONCLUSIONS: These findings underscore the sex specificity of NAFLD pathophysiology in preclinical studies and identify PPARα as a pivotal, sexually dimorphic, pharmacological target. TRIAL REGISTRATION NUMBER: NCT02390232.

Inflammation in alcohol-associated liver disease progression.

Chronic alcohol consumption induces stress and damage in alcohol metabolising hepatocytes, which leads to inflammatory and fibrogenic responses. Besides these direct effects, alcohol disrupts intestinal barrier functions and induces gut microbial dysbiosis, causing translocation of bacteria or microbial products through the gut mucosa to the liver and, which induce inflammation indirectly. Inflammation is one of the key drivers of alcohol-associated liver disease progression from steatosis to severe alcoholic hepatitis. The current standard of care for the treatment of severe alcoholic hepatitis is prednisolone, aiming to reduce inflammation. Prednisolone, however improves only short-term but not long-term survival rates in those patients, and even increases the risk for bacterial infections. Thus, recent studies focus on the exploration of more specific inflammatory targets for the treatment of severe alcoholic hepatitis. These comprise, among others interference with inflammatory cytokines, modulation of macrophage phenotypes or targeting of immune cell communication, as summarized in the present overview. Although several approaches give promising results in preclinical studies, data robustness and ability to transfer experimental results to human disease is still not sufficient for effective clinical translation.

Targeting cell-intrinsic metabolism for antifibrotic therapy.

In recent years, there have been major advances in our understanding of the mechanisms underlying fibrosis progression and regression, and how coordinated interactions between parenchymal and non-parenchymal cells impact on the fibrogenic process. Recent studies have highlighted that metabolic reprogramming of parenchymal cells, immune cells (immunometabolism) and hepatic stellate cells is required to support the energetic and anabolic demands of phenotypic changes and effector functions. In this review, we summarise how targeting cell-intrinsic metabolic modifications of the main fibrogenic cell actors may impact on fibrosis progression and we discuss the antifibrogenic potential of metabolically targeted interventions.

Monoacylglycerol Lipase Inhibition Protects From Liver Injury in Mouse Models of Sclerosing Cholangitis.

BACKGROUND AND AIMS: Monoacylglycerol lipase (MGL) is the last enzymatic step in triglyceride degradation, hydrolyzing monoglycerides into glycerol and fatty acids (FAs) and converting 2-arachidonoylglycerol into arachidonic acid, thus providing ligands for nuclear receptors as key regulators of hepatic bile acid (BA)/lipid metabolism and inflammation. We aimed to explore the role of MGL in the development of cholestatic liver and bile duct injury in mouse models of sclerosing cholangitis, a disease so far lacking effective pharmacological therapy. APPROACH AND RESULTS: To this aim we analyzed the effects of 3,5-diethoxycarbonyl-1,4-dihydrocollidine (DDC) feeding to induce sclerosing cholangitis in wild-type (WT) and knockout (MGL-/- ) mice and tested pharmacological inhibition with JZL184 in the multidrug resistance protein 2 knockout (Mdr2-/- ) mouse model of sclerosing cholangitis. Cholestatic liver injury and fibrosis were assessed by serum biochemistry, liver histology, gene expression, and western blot characterization of BA and FA synthesis/transport. Moreover, intestinal FAs and fecal microbiome were analyzed. Transfection and silencing were performed in Caco2 cells. MGL-/- mice were protected from DDC-induced biliary fibrosis and inflammation with reduced serum liver enzymes and increased FA/BA metabolism and ß-oxidation. Notably, pharmacological (JZL184) inhibition of MGL ameliorated cholestatic injury in DDC-fed WT mice and protected Mdr2-/- mice from spontaneous liver injury, with improved liver enzymes, inflammation, and biliary fibrosis. In vitro experiments confirmed that silencing of MGL decreases prostaglandin E2 accumulation in the intestine and up-regulates peroxisome proliferator-activated receptors alpha and gamma activity, thus reducing inflammation. CONCLUSIONS: Collectively, our study unravels MGL as a metabolic target, demonstrating that MGL inhibition may be considered as potential therapy for sclerosing cholangitis.

A defect in endothelial autophagy occurs in patients with non-alcoholic steatohepatitis and promotes inflammation and fibrosis.

BACKGROUND & AIMS: Previous studies demonstrated that autophagy is protective in hepatocytes and macrophages, but detrimental in hepatic stellate cells in chronic liver diseases. The role of autophagy in liver sinusoidal endothelial cells (LSECs) in non-alcoholic steatohepatitis (NASH) is unknown. Our aim was to analyze the potential implication of autophagy in LSECs in NASH and liver fibrosis. METHODS: We analyzed autophagy in LSECs from patients using transmission electron microscopy. We determined the consequences of a deficiency in autophagy: (a) on LSEC phenotype, using primary LSECs and an LSEC line; (b) on early stages of NASH and on advanced stages of liver fibrosis, using transgenic mice deficient in autophagy specifically in endothelial cells and fed a high-fat diet or chronically treated with carbon tetrachloride, respectively. RESULTS: Patients with NASH had half as many LSECs containing autophagic vacuoles as patients without liver histological abnormalities, or with simple steatosis. LSECs from mice deficient in endothelial autophagy displayed an upregulation of genes implicated in inflammatory pathways. In the LSEC line, deficiency in autophagy enhanced inflammation (Ccl2, Ccl5, Il6 and VCAM-1 expression), features of endothelial-to-mesenchymal transition (α-Sma, Tgfb1, Col1a2 expression) and apoptosis (cleaved caspase-3). In mice fed a high-fat diet, deficiency in endothelial autophagy induced liver expression of inflammatory markers (Ccl2, Ccl5, Cd68, Vcam-1), liver cell apoptosis (cleaved caspase-3) and perisinusoidal fibrosis. Mice deficient in endothelial autophagy treated with carbon tetrachloride also developed more perisinusoidal fibrosis. CONCLUSIONS: A defect in autophagy in LSECs occurs in patients with NASH. Deficiency in endothelial autophagy promotes the development of liver inflammation, features of endothelial-to-mesenchymal transition, apoptosis and liver fibrosis in the early stages of NASH, but also favors more advanced stages of liver fibrosis. LAY SUMMARY: Autophagy is a physiological process controlling endothelial homeostasis in vascular beds outside the liver. This study demonstrates that autophagy is defective in the liver endothelial cells of patients with non-alcoholic steatohepatitis. This defect promotes liver inflammation and fibrosis at early stages of non-alcoholic steatohepatitis, but also at advanced stages of chronic liver disease.

Recent Advances in Practical Methods for Liver Cell Biology: A Short Overview.

Molecular and cellular research modalities for the study of liver pathologies have been tremendously improved over the recent decades. Advanced technologies offer novel opportunities to establish cell isolation techniques with excellent purity, paving the path for 2D and 3D microscopy and high-throughput assays (e.g., bulk or single-cell RNA sequencing). The use of stem cell and organoid research will help to decipher the pathophysiology of liver diseases and the interaction between various parenchymal and non-parenchymal liver cells. Furthermore, sophisticated animal models of liver disease allow for the in vivo assessment of fibrogenesis, portal hypertension and hepatocellular carcinoma (HCC) and for the preclinical testing of therapeutic strategies. The purpose of this review is to portray in detail novel in vitro and in vivo methods for the study of liver cell biology that had been presented at the workshop of the 8th meeting of the European Club for Liver Cell Biology (ECLCB-8) in October of 2018 in Bonn, Germany.

Inhibition of monoacylglycerol lipase, an anti-inflammatory and antifibrogenic strategy in the liver.

OBJECTIVE: Sustained inflammation originating from macrophages is a driving force of fibrosis progression and resolution. Monoacylglycerol lipase (MAGL) is the rate-limiting enzyme in the degradation of monoacylglycerols. It is a proinflammatory enzyme that metabolises 2-arachidonoylglycerol, an endocannabinoid receptor ligand, into arachidonic acid. Here, we investigated the impact of MAGL on inflammation and fibrosis during chronic liver injury. DESIGN: C57BL/6J mice and mice with global invalidation of MAGL (MAGL -/- ), or myeloid-specific deletion of either MAGL (MAGLMye-/-), ATG5 (ATGMye-/-) or CB2 (CB2Mye-/-), were used. Fibrosis was induced by repeated carbon tetrachloride (CCl4) injections or bile duct ligation (BDL). Studies were performed on peritoneal or bone marrow-derived macrophages and Kupffer cells. RESULTS: MAGL -/- or MAGLMye-/- mice exposed to CCl4 or subjected to BDL were more resistant to inflammation and fibrosis than wild-type counterparts. Therapeutic intervention with MJN110, an MAGL inhibitor, reduced hepatic macrophage number and inflammatory gene expression and slowed down fibrosis progression. MAGL inhibitors also accelerated fibrosis regression and increased Ly-6Clow macrophage number. Antifibrogenic effects exclusively relied on MAGL inhibition in macrophages, since MJN110 treatment of MAGLMye-/- BDL mice did not further decrease liver fibrosis. Cultured macrophages exposed to MJN110 or from MAGLMye-/- mice displayed reduced cytokine secretion. These effects were independent of the cannabinoid receptor 2, as they were preserved in CB2Mye-/- mice. They relied on macrophage autophagy, since anti-inflammatory and antifibrogenic effects of MJN110 were lost in ATG5Mye-/- BDL mice, and were associated with increased autophagic flux and autophagosome biosynthesis in macrophages when MAGL was pharmacologically or genetically inhibited. CONCLUSION: MAGL is an immunometabolic target in the liver. MAGL inhibitors may show promising antifibrogenic effects during chronic liver injury.

Lack of monoacylglycerol lipase prevents hepatic steatosis by favoring lipid storage in adipose tissue and intestinal malabsorption.

Monoacylglycerol lipase (MGL) is the rate-limiting enzyme in the degradation of monoacylglycerols. To examine the role of MGL in hepatic steatosis, WT and MGL KO (MGL-/-) mice were challenged with a Western diet (WD) over 12 weeks. Lipid metabolism, inflammation, and fibrosis were assessed by serum biochemistry, histology, and gene-expression profiling of liver and adipose depots. Intestinal fat absorption was measured by gas chromatography. Primary adipocyte and 3T3-L1 cells were analyzed by flow cytometry and Western blot. Human hepatocytes were treated with MGL inhibitor JZL184. The absence of MGL protected mice from hepatic steatosis by repressing key lipogenic enzymes in liver (Srebp1c, Pparγ2, and diacylglycerol O-acyltransferase 1), while promoting FA oxidation. Liver inflammation was diminished in MGL-/- mice fed a WD, as evidenced by diminished epidermal growth factor-like module-containing mucin-like hormone receptor-like 1 (F4/80) staining and C-C motif chemokine ligand 2 gene expression, whereas fibrosis remained unchanged. Absence of MGL promoted fat storage in gonadal white adipose tissue (gWAT) with increased lipogenesis and unchanged lipolysis, diminished inflammation in gWAT, and subcutaneous AT. Intestinal fat malabsorption prevented ectopic lipid accumulation in livers of MGL-/- mice fed a WD. In vitro experiments demonstrated increased adipocyte size/lipid content driven by PPARγ. In conclusion, our data uncover that MGL deletion improves some aspects of nonalcoholic fatty liver disease by promoting lipid storage in gWAT and fat malabsorption.

Autophagy in liver diseases: Time for translation?

Autophagy is a self-eating catabolic pathway that contributes to liver homeostasis through its role in energy balance and in the quality control of the cytoplasm, by removing misfolded proteins, damaged organelles and lipid droplets. Autophagy not only regulates hepatocyte functions but also impacts on non-parenchymal cells, such as endothelial cells, macrophages and hepatic stellate cells. Deregulation of autophagy has been linked to many liver diseases and its modulation is now recognized as a potential new therapeutic strategy. Indeed, enhancing autophagy may prevent the progression of a number of liver diseases, including storage disorders (alpha-1 antitrypsin deficiency, Wilson's disease), acute liver injury, non-alcoholic steatohepatitis and chronic alcohol-related liver disease. Nevertheless, in some situations such as fibrosis, targeting specific liver cells must be considered, as autophagy displays opposing functions depending on the cell type. In addition, an optimal therapeutic time-window should be identified, since autophagy might be beneficial in the initial stages of disease, but detrimental at more advanced stages, as in the case of hepatocellular carcinoma. Finally, identifying biomarkers of autophagy and methods to monitor autophagic flux in vivo are important steps for the future development of personalized autophagy-targeting strategies. In this review, we provide an update on the regulatory role of autophagy in various aspects of liver pathophysiology, describing the different strategies to manipulate autophagy and discussing the potential to modulate autophagy as a therapeutic strategy in the context of liver diseases.

Combination of CCl4 with alcoholic and metabolic injuries mimics human liver fibrosis.

Metabolic and alcoholic liver injuries result in nonalcoholic (NAFLD) or alcoholic (ALD) fatty liver disease, respectively. In particular, presence of fibrosis in NAFLD and ALD requires treatment, but development of drugs is hampered by the lack of suitable models with significant fibrosis. The carbon tetrachloride (CCl4) liver fibrosis model does not reflect human NAFLD or ALD, but CCl4 may serve as a fibrosis accelerator in addition to another injury. Ethanol in drinking water (16%) or Western diet (WD) were administered for 7 wk in mice either alone or in combination with CCl4 intoxications. Extent of fibrosis, steatosis, and inflammation was assessed by histology, transcription, and biochemistry. Furthermore, transcription of fibrosis, proliferation, and inflammation-related genes was studied on human liver samples with fibrosis resulting from hepatitis C virus infection (n = 7), NAFLD (n = 8), or ALD (n = 7). WD or ethanol alone induced only mild steatosis and inflammation. Combination of CCl4 and WD induced the most severe steatosis together with significant liver fibrosis and moderate inflammation. Combination of CCl4 and ethanol induced the strongest inflammation, with significant liver fibrosis and moderate steatosis. The relationship pattern between fibrosis, proliferation, and inflammation of human ALD was mostly similar in mice treated with CCl4 and ethanol. The combination of CCl4 intoxication with WD validates previous data suggesting it as an appropriate model for human nonalcoholic steatohepatitis. Especially, CCl4 plus ethanol for 7 wk induces ALD in mice, providing a model suitable for further basic research and drug testing.NEW & NOTEWORTHY Alcoholic fatty liver disease with significant fibrosis is generated within 7 wk using carbon tetrachloride as a fibrosis accelerator and administering gradually ethanol (up to 16%) in mice. The similarity in the pattern of steatosis, inflammation, and fibrosis involved in alcoholic fatty liver disease to those of the human condition renders this mouse model suitable as a preclinical model for drug development.

In vitro distinction between proinflammatory and antiinflammatory macrophages with gadolinium-liposomes and ultrasmall superparamagnetic iron oxide particles at 3.0T.

BACKGROUND: Inflammation involves a heterogeneous macrophage population, for which there is no readily available MR assessment method. PURPOSE: To assess the feasibility of distinguishing proinflammatory M1 and antiinflammatory M2 macrophages at MRI enhanced with gadolinium liposomes or ultrasmall superparamagnetic iron oxide particles. STUDY TYPE: In vitro. SPECIMEN: We employed cultured RAW macrophages. M0 macrophages were polarized with lipopolysaccharide (LPS) or interleukin-4 (IL-4), resulting in M1 or M2 macrophages. The macrophages were incubated with gadolinium (±rhodamine) liposomes or iron oxide particles and cell pellets were prepared for MRI. FIELD STRENGTH/SEQUENCE: Transverse relaxation rates and quantitative susceptibility were obtained at 3.0T with multiecho turbo spin echo and spoiled gradient echo sequences. ASSESSMENT: MRI results were compared with confocal microscopy, flow cytometry, and expression of endocytosis, M1 and M2 genes. STATISTICAL TESTS: Mann-Whitney and Kruskal-Wallis tests were performed. RESULTS: Higher transverse relaxation rates and susceptibility were observed in M1 than in M2 and M0 macrophages (P < 0.01 both with liposomes and USPIO) and significantly different susceptibility in M2 and M0 macrophages (P < 0.01 both with liposomes and USPIO). These MRI results were confirmed at confocal microscopy and flow cytometry. LPS macrophages displayed M1 gene expression, whereas IL-4 macrophages showed M2 polarization and lower endocytosis gene expression rates. DATA CONCLUSION: These in vitro results show that it is feasible to distinguish between proinflammatory M1 and antiinflammatory M2 macrophages according to their level of contrast agent uptake at MRI. LEVEL OF EVIDENCE: 1 Technical Efficacy: Stage 1 J. Magn. Reson. Imaging 2019;49:1166-1173.

Autophagy in chronic liver diseases: the two faces of Janus.

Alcoholic liver disease (ALD) and nonalcoholic fatty liver disease (NAFLD) are the leading causes of cirrhosis and increase the risk of hepatocellular carcinoma and liver-related death. ALD and NAFLD share common pathogenic features extending from isolated steatosis to steatohepatitis and steatofibrosis, which can progress to cirrhosis and hepatocellular carcinoma. The pathophysiological mechanisms of the progression of NAFLD and ALD are complex and still unclear. Important links between the regulation of autophagy (macroautophagy and chaperone-mediated autophagy) and chronic liver diseases have been reported. Autophagy may protect against steatosis and progression to steatohepatitis by limiting hepatocyte injury and reducing M1 polarization, as well as promoting liver regeneration. Its role in fibrosis and hepatocarcinogenesis is more complex. It has pro- and antifibrogenic properties depending on the hepatic cell type concerned, and beneficial and deleterious effects on hepatocarcinogenesis at initiating and late phases, respectively. This review summarizes the latest advances on the role of autophagy in different stages of fatty liver disease progression and describes its divergent and cell-specific effects during chronic liver injury.

Type I interferon signaling in systemic immune cells from patients with alcoholic cirrhosis and its association with outcome.

BACKGROUND & AIMS: In immune cells, constitutively and acutely produced type I interferons (IFNs) engage autocrine/paracrine signaling pathways to induce IFN-stimulated genes (ISGs). Enhanced activity of IFN signaling pathways can cause excessive inflammation and tissue damage. We aimed to investigate ISG expression in systemic immune cells from patients with decompensated alcoholic cirrhosis, and its association with outcome. METHODS: Peripheral blood mononuclear cells (PBMCs) from patients and heathy subjects were stimulated or not with lipopolysaccharide (LPS, an IFN inducer) or increasing concentrations of IFN-ß. The expression of 48 ISGs and ten "non-ISG" inflammatory cytokines were analyzed using RT-qPCR. RESULTS: We developed an 8-ISG signature (IFN score) assessing ISG expression. LPS-stimulated ISG induction was significantly lower in PBMCs from patients with cirrhosis compared to healthy controls. Non-ISGs, however, showed higher induction. Lower induction of ISGs by LPS was not due to decreased IFN production by cirrhotic PBMCs or neutralization of secreted IFN, but a defective PBMC response to IFN. This defect was at least in part due to decreased constitutive ISG expression. Patients with the higher baseline IFN scores and ISG levels had the higher risk of death. At baseline, "non-ISG" cytokines did not correlate with outcome. CONCLUSIONS: PBMCs from patients with decompensated alcoholic cirrhosis exhibit downregulated ISG expression, both constitutively and after an acute stimulus. Our finding that higher baseline PBMC ISG expression was associated with higher risk of death, suggests that constitutive ISG expression in systemic immune cells contributes to the prognosis of alcoholic cirrhosis. LAY SUMMARY: Enhanced activity of IFN signaling pathways can cause excessive inflammation and tissue damage. Here we show that peripheral blood mononuclear cells (PBMCs) from patients with alcoholic cirrhosis exhibit a defect in interferon-stimulated genes (ISGs). We found that higher baseline ISG expression in PBMCs was associated with higher risk of death, revealing a probable contribution of ISG expression in immune cells to the outcome of alcoholic cirrhosis.

Upregulation of Epac-1 in Hepatic Stellate Cells by Prostaglandin E2 in Liver Fibrosis Is Associated with Reduced Fibrogenesis.

Exchange protein activated by cAMP (Epac-1) is an important signaling mechanism for cAMP-mediated effects, yet factors that change Epac-1 levels are unknown. Such factors are relevant because it has been postulated that Epac-1 directly affects fibrogenesis. Prostaglandin E2 (PGE2) is a well-known cAMP activator, and we therefore studied the effects of this cyclo-oxygenase product on Epac-1 expression and on fibrogenesis within the liver. Liver fibrosis was induced by 8 weeks carbon tetrachloride (CCL4) administration to mice. In the last 2 weeks, mice received vehicle, PGE2, the cyclo-oxygenase-2 inhibitor niflumic acid (NFA), or PGE2 coupled to cell-specific carriers to hepatocytes, Kupffer cells, or hepatic stellate cells (HSC). Results showed antifibrotic effects of PGE2 and profibrotic effects of NFA in CCL4 mice. Western blot analysis revealed reduced Epac-1 protein expression in fibrotic livers of mice and humans compared with healthy livers. PGE2 administration to fibrotic mice completely restored intrahepatic Epac-1 levels and also led to reduced Rho kinase activity, a downstream target of Epac-1. Cell-specific delivery of PGE2 to either hepatocytes, Kupffer cells, or HSC identified the latter cell as the key player in the observed effects on Epac-1 and Rho kinase. No significant alterations in protein kinase A expressions were found. In primary isolated HSC, PGE2 elicited Rap1 translocation reflecting Epac-1 activation, and Epac-1 agonists attenuated platelet-derived growth factor-induced proliferation and migration of these cells. These studies demonstrate that PGE2 enhances Epac-1 activity in HSC, which is associated with significant changes in (myo)fibroblast activities in vitro and in vivo. Therefore, Epac-1 is a potential target for antifibrotic drugs.

Statins Modulate Cyclooxygenase-2 and Microsomal Prostaglandin E Synthase-1 in Human Hepatic Myofibroblasts.

Statins have been shown to exert anti-inflammatory and anti-fibrogenic properties in the liver. In the present study, we explored the mechanisms underlying anti-fibrogenic effects of statins in isolated hepatic myofibroblasts and focused on cyclooxyegnase-2, a major anti-proliferative pathway in these cells. We show that simvastatin and fluvastatin inhibit thymidine incorporation in hMF in a dose-dependent manner. Pretreatment of cells with NS398, a COX-2 inhibitor, partially blunted this effect. cAMP levels, essential to the inhibition of hMF proliferation, were increased by statins and inhibited by non-steroidal anti-inflammatory drugs. Since statins modify prenylation of some important proteins in gene expression, we investigated the targets involved using selective inhibitors of prenyltransferases. Inhibition of geranylgeranylation resulted in the induction of COX-2 and mPGES-1. Using gel retardation assays, we further demonstrated that statins potentially activated the NFκB and CRE/E-box binding for COX-2 promoter and the binding of GC-rich regions and GATA for mPGES-1. Together these data demonstrate that statin limit hepatic myofibroblasts proliferation via a COX-2 and mPGES-1 dependent pathway. These data suggest that statin-dependent increase of prostaglandin in hMF contributes to its anti-fibrogenic effect.

Novel role for carbohydrate responsive element binding protein in the control of ethanol metabolism and susceptibility to binge drinking.

UNLABELLED: Carbohydrate responsive element binding protein (ChREBP) is central for de novo fatty acid synthesis under physiological conditions and in the context of nonalcoholic fatty liver disease. We explored its contribution to alcohol-induced steatosis in a mouse model of binge drinking as acute ethanol (EtOH) intoxication has become an alarming health problem. Within 6 hours, ChREBP acetylation and its recruitment onto target gene promoters were increased in liver of EtOH-fed mice. Acetylation of ChREBP was dependent on alcohol metabolism because inhibition of alcohol dehydrogenase (ADH) activity blunted ChREBP EtOH-induced acetylation in mouse hepatocytes. Transfection of an acetylation-defective mutant of ChREBP (ChREBP(K672A) ) in HepG2 cells impaired the stimulatory effect of EtOH on ChREBP activity. Importantly, ChREBP silencing in the liver of EtOH-fed mice prevented alcohol-induced triglyceride accumulation through an inhibition of the lipogenic pathway but also led, unexpectedly, to hypothermia, increased blood acetaldehyde concentrations, and enhanced lethality. This phenotype was associated with impaired hepatic EtOH metabolism as a consequence of reduced ADH activity. While the expression and activity of the NAD(+) dependent deacetylase sirtuin 1, a ChREBP-negative target, were down-regulated in the liver of alcohol-fed mice, they were restored to control levels upon ChREBP silencing. In turn, ADH acetylation was reduced, suggesting that ChREBP regulates EtOH metabolism and ADH activity through its direct control of sirtuin 1 expression. Indeed, when sirtuin 1 activity was rescued by resveratrol pretreatment in EtOH-treated hepatocytes, a significant decrease in ADH protein content and/or acetylation was observed. CONCLUSION: our study describes a novel role for ChREBP in EtOH metabolism and unravels its protective effect against severe intoxication in response to binge drinking.

Human hepatic stellate cells are not permissive for hepatitis C virus entry and replication.

BACKGROUND: Chronic HCV infection is associated with the development of hepatic fibrosis. The direct role of HCV in the fibrogenic process is unknown. Specifically, whether HCV is able to infect hepatic stellate cells (HSCs) is debated. OBJECTIVE: To assess whether human HSCs are susceptible to HCV infection. DESIGN: We combined a set of original HCV models, including the infectious genotype 2a JFH1 model (HCVcc), retroviral pseudoparticles expressing the folded HCV genotype 1b envelope glycoproteins (HCVpp) and a subgenomic genotype 1b HCV replicon, and two relevant cellular models, primary human HSCs from different patients and the LX-2 cell line, to assess whether HCV can infect/replicate in HSCs. RESULTS: In contrast with the hepatocyte cell line Huh-7, neither infectious HCVcc nor HCVpp infected primary human HSCs or LX-2 cells. The cellular expression of host cellular factors required for HCV entry was high in Huh-7 cells but low in HSCs and LX-2 cells, with the exception of CD81. Finally, replication of a genotype 2a full-length RNA genome and a genotype 1b subgenomic replicon was impaired in primary human HSCs and LX-2 cells, which expressed low levels of cellular factors known to play a key role in the HCV life-cycle, suggesting that human HSCs are not permissive for HCV replication. CONCLUSIONS: Human HSCs are refractory to HCV infection. Both HCV entry and replication are deficient in these cells, regardless of the HCV genotype and origin of the cells. Thus, HCV infection of HSCs does not play a role in liver fibrosis. These results do not rule out a direct role of HCV infection of hepatocytes in the fibrogenic process.

M2 kupffer cells promote hepatocyte senescence: an IL-6-dependent protective mechanism against alcoholic liver disease.

Alcoholic liver disease is a predominant cause of liver-related mortality in Western countries. The early steps of alcohol-induced steatosis and liver injury involve several mechanisms, including inflammation and oxidative stress. The inflammatory process is initiated by polarization of Kupffer cells toward a proinflammatory M1 phenotype, and we recently found that promoting anti-inflammatory M2 Kupffer cell polarization protects against alcohol-induced hepatocyte steatosis and apoptosis. Alcohol-induced oxidative stress is a potential trigger of senescence, and senescent cells exhibit characteristic functional resistance to apoptosis. We sought to evaluate induction of hepatocyte senescence as an early protective mechanism against alcoholic liver disease. Combining in vivo and in vitro studies, we show that M2 macrophages trigger hepatocyte senescence and enhance alcohol-induced hepatocyte senescence, as indicated by increased ß-galactosidase activity, elevated CDKN1A mRNA expression, and induction of nuclear p21. We identify IL-6 as the mediator of M2-induced hepatocyte senescence. Senescent hepatocytes display characteristic resistance to apoptosis but also to steatosis, thus arguing for an early protective effect against alcoholic liver disease. These findings further suggest that pharmacologic interventions targeting M2 polarization during the early stages of alcoholic liver disease may represent an attractive strategy for the limitation of inflammation, hepatocyte apoptosis, and steatosis.