Genes or environment to determine alcoholic liver disease and non-alcoholic fatty liver disease

Circulatory Metabolite Ratios as Indicators of Lifestyle Risk Factors Based on a Greek NAFLD Case-Control Study

An ensemble of confounding factors, such as an unhealthy diet, obesity, physical inactivity, and smoking, have been linked to a lifestyle that increases one's susceptibility to chronic diseases and early mortality. The circulatory metabolome may provide a rational means of pinpointing the advent of metabolite variations that reflect an adherence to a lifestyle and are associated with the occurrence of chronic diseases. Data related to four major modifiable lifestyle factors, including adherence to the Mediterranean diet (estimated on MedDietScore), body mass index (BMI), smoking, and physical activity level (PAL), were used to create the lifestyle risk score (LS). The LS was further categorized into four groups, where a higher score group indicates a less healthy lifestyle. Drawing on this, we analyzed 223 NMR serum spectra, 89 MASLD patients and 134 controls; these were coupled to chemometrics to identify "key" features and understand the biological processes involved in specific lifestyles. The unsupervised analysis verified that lifestyle was the factor influencing the samples' differentiation, while the supervised analysis highlighted metabolic signatures. Τhe metabolic ratios of alanine/formic acid and leucine/formic acid, with AUROC > 0.8, may constitute discriminant indexes of lifestyle. On these grounds, this research contributed to understanding the impact of lifestyle on the circulatory metabolome and highlighted "prudent lifestyle" biomarkers.

Development and Validation of a Noninvasive Risk Score Model for Liver Cirrhosis in At-Risk Alcohol Drinkers Without HBV/HCV Infection

At-risk alcohol consumption is the established most important risk factor for cirrhosis in people without HBV/HCV infection. We aimed to develop and validate a simple and non-invasive tool for triaging cirrhosis risk in at-risk alcohol drinkers without HBV/HCV infection. A large-sample size, cross-sectional study within the framework of a population-based Cancer Screening Program in Urban China (CanSPUC) was conducted. Data on the liver cancer screening in Henan province, China were used. At-risk alcohol drinkers were those who currently drink one or more alcohol units per week for at least six months. A total of 6,581 eligible participants enrolled from October 1, 2013 to December 31, 2016 were included into the derivation dataset, and 2,096 eligible participants enrolled from January 1, 2017 to October 31, 2018 were included into the external validation dataset, respectively. Using the derivation dataset, a 20-point scale risk score model was developed, based on sex, education background, dietary intake of vegetables, dietary intake of roughage, smoking index, length of secondhand smoke exposure, history of fatty liver, history of diabetes, and first-degree family history of liver cancer. The model showed excellent discrimination (AUC  =  0.787; 95% CI, 0.7603-0.812) and calibration (Hosmer-Lemeshow test: P = 0.123) in the derivation dataset and an optimal cut-off value of 12 yield sensitivity of 61.3%, specificity of 82.7%. The model also had achieved similar performance in the external validation dataset. In conclusion, this model can be a practical tool to identify and triage population at high risk of cirrhosis in at-risk alcohol drinkers without HBV/HCV infection.

PREVENTION RELEVANCE

The risk model we developed will not only be used as a practical tool to triage high risk groups for liver cirrhosis, but also have implications for public health measures, such as guidelines for the prevention of liver cancer, in at-risk alcohol drinkers without HBV/HCV infection.

Long noncoding RNAs associated with nonalcoholic fatty liver disease in a high cholesterol diet adult zebrafish model

The mechanism of nonalcoholic fatty liver disease (NAFLD) has not been completely revealed. In this study, we investigated the association of liver histological changes and long noncoding RNAs (lncRNAs) in the NAFLD zebrafish model. Forty zebrafish were fed a high-cholesterol diet (1.5 g per day) for 8 weeks. We measured fatty liver changes in the zebrafish liver using oil red O staining and divided them into two groups based on high and low scores. We pooled each group of zebrafish livers and identified lncRNAs, miRNAs, and mRNAs using Next-generation sequencing. Human homologs of lncRNAs were identified using ZFLNC, Ensembl, and NONCODE. We found several significant genes, including 32 lncRNAs, 5 miRNA genes, and 8 protein-coding genes, that were associated with liver metabolism and NAFLD-related functions in zebrafish. In particular, eight conserved human homologs of lncRNAs were found. We discovered the human homologs of eight lncRNA candidates from fatty liver zebrafish for the first time. The spectrum of biological mechanisms by which lncRNAs mediate their functional roles in NAFLD in a high cholesterol diet adult zebrafish model remains to be uncovered.

Pre-exposure to TiO2-NPs aggravates alcohol-related liver injury by inducing intestinal barrier damage in mice

The wide application of TiO2 nanoparticles (NPs) and the increase in opportunities for its release into the environment undoubtedly compound the potential of these materials to harm people. Research on the effects of pre-exposure to TiO2-NPs on disease development is scarce. The purpose of this work was to assess whether pre-exposure to TiO2-NPs (20 mg/kg and 200 mg/kg) for 28 days aggravates the development of alcohol-related liver injury in mice. Results showed that oral administration of 200 mg/kg TiO2-NPs induced only modest changes in liver function parameters, but could induce intestinal inflammation and destroy the integrity of intestinal barrier. After the subsequent alcohol intervention, pre-exposure to TiO2-NPs (200 mg/kg) was found to aggravate alcohol-related liver injury, including significantly increases in serum Aspartate aminotransferase (AST), Alanine aminotransferase (ALT), Total glycerol (TG), and Total cholesterol (TC), as well as steatosis and inflammation in the liver. Further investigation revealed that alcohol could increase intestinal permeability and reduce the expression of tight junction proteins in mice pre-exposed high dosage of TiO2-NPs, thereby inducing the transfer of more lipopolysaccharides (LPS) into the liver, ultimately triggering more severe liver inflammation. This study emphasizes that pre-exposed of TiO2-NPs (high doses of up to 200 mg/kg) can potentially promote the development of alcoholic liver diseases. Furthermore, this study provides new insights into evaluating the safety of NPs.

Associations of Nutritional, Lifestyle, and Metabolic Factors With Non-alcoholic Fatty Liver Disease: An Umbrella Review With More Than 380,000 Participants

Background & Aims: Nonalcoholic fatty liver disease (NAFLD) is the most common liver injury. We performed this umbrella review of meta-analyses to summarize the evidence on the associations of nutritional, lifestyle, and metabolic factors with NAFLD.

Methods: We searched the PubMed, Embase, and Web of Science databases from inception until July 2, 2020, to identify meta-analyses of observational studies which explored the associations of nutritional, lifestyle, and metabolic factors with NAFLD. Evidence levels were assessed using summary effect sizes, 95% prediction intervals, between-study heterogeneity, evidence of small-study effects, and evidence of excess significance bias for each meta-analysis. (No. of PROSPERO, CRD42020200124).

Results: Twenty two risk or protective factors from 10 published meta-analyses were included and studied. Three risk factors (sugar-sweetened beverage consumption, serum fetuin-A, and waist circumference) with highly suggestive levels of evidence and three risk factors (soft drink consumption, former smoking, and body mass index) with suggestive levels of evidence were identified. Only two protective factors (physical activity and serum vitamin D level [among adults in Western countries]) with suggestive levels of evidence were identified. Furthermore, other six risk factors and two protective factors with weak levels of evidence were identified.

Conclusions: We found varying levels of evidence of associations of nutritional, lifestyle, and metabolic factors and NAFLD. The results suggest that nutritional and lifestyle management should be considered as a major primary preventive strategy for NAFLD. Moreover, considering the low quality of included meta-analyses and limited area of research topics, future high-quality original studies and meta-analyses should be performed to study these associations.

Trends in Premature Deaths From Alcoholic Liver Disease in the U.S., 1999-2018

INTRODUCTION

So-called deaths of despair-those involving drug overdoses, alcohol-related liver disease, and suicide-have been rising in the U.S. among middle-aged white, non-Hispanic adults without a college degree. Premature deaths (ages 25-69) from alcoholic liver disease were examined specifically in this study from 1999 to 2018, by sex, race/Hispanic origin, and age group.

METHODS

Data were drawn from the 1999-2018 Multiple Cause of Death database and bridged-race estimates of the U.S. resident population, including 281,243 alcoholic liver disease deaths or an average of 8 deaths per 100,000 population. Analyses examined alcoholic liver disease death rates for sex differences among 3 age groups (25-49, 50-59, and 60-69 years), by race and Hispanic origin, from 1999 to 2018; age-adjusted and age-specific annual percentage changes (accounted for cohorts); years of potential life lost; and age of death for sociodemographic backgrounds, alcoholic liver disease clinical courses, and comortalities.

RESULTS

White non-Hispanics increasingly experienced greater alcoholic liver disease mortality than black non-Hispanics and Hispanics, confirming the racial and ethnic crossover observed in previous studies. Although men consistently had higher rates of mortality, male-to-female ratios decreased in the past 2 decades and were the lowest among ages 25-49 years and especially among ages 25-34 years. Although women generally had longer life expectancies, women died of alcoholic liver disease on average about 2-3 years earlier than men.

CONCLUSIONS

Prevention and intervention efforts are imperative to address the narrowing sex gap and widening racial disparities in alcoholic liver disease premature deaths.

Differentially expressed mRNAs and lncRNAs shared between activated human hepatic stellate cells and nash fibrosis

We previously reported dysregulated expression of liver-derived messenger RNA (mRNA) and long noncoding RNA (lncRNA) in patients with advanced fibrosis resulting from nonalcoholic fatty liver disease (NAFLD). Here we sought to identify changes in mRNA and lncRNA levels associated with activation of hepatic stellate cells (HSCs), the predominant source of extracellular matrix production in the liver and key to NAFLD-related fibrogenesis. We performed expression profiling of mRNA and lncRNA from LX-2 cells, an immortalized human HSC cell line, treated to induce phenotypes resembling quiescent and myofibroblastic states. We identified 1964 mRNAs (1377 upregulated and 587 downregulated) and 1460 lncRNAs (665 upregulated and 795 downregulated) showing statistically significant evidence (FDR ≤0.05) for differential expression (fold change ≥|2|) between quiescent and activated states. Pathway analysis of differentially expressed genes showed enrichment for hepatic fibrosis (FDR = 1.35E-16), osteoarthritis (FDR = 1.47E-14), and axonal guidance signaling (FDR = 1.09E-09). We observed 127 lncRNAs/nearby mRNA pairs showing differential expression, the majority of which were dysregulated in the same direction. A comparison of differentially expressed transcripts in LX-2 cells with RNA-sequencing results from NAFLD patients with or without liver fibrosis revealed 1047 mRNAs and 91 lncRNAs shared between the two datasets, suggesting that some of the expression changes occurring during HSC activation can be observed in biopsied human tissue. These results identify lncRNA and mRNA expression patterns associated with activated human HSCs that appear to recapitulate human NAFLD fibrosis.

In vitro effects of cobalt nanoparticles on aspartate aminotransferase and alanine aminotransferase activities of wistar rats

Cobalt nanoparticles (Co-NPs) have been extensively used in clinical practices and medical diagnosis. In this study, the potential toxicity effects of Co-NPs with special emphasis over the biochemical enzyme activities, such as aspartate aminotransferase (ASAT) and alanine aminotransferase (ALAT) in serum, liver, and kidney of Wistar rats were investigated. This toxicity measurement of nanomaterials can support the toxicological data. The biochemical enzymatic variations are powerful tools for the assessment of toxicity. ASAT and ALAT enzymes have been widely used to predict tissue-specific toxicities associated with xenobiotic. The biochemical changes induced by Co-NPs have significance in their toxicological studies because the alterations in biochemical parameters before clinical symptoms indicate either their toxicant safety or detrimental effect. Herein, Co-NPs with particle size <50 nm significantly activated ASAT and ALAT enzymes in the serum, liver, and kidney of rats at concentration-dependent order.

Non-alcoholic fatty liver diseases: from role of gut microbiota to microbial-based therapies

Non-alcoholic fatty liver disease (NAFLD) is the well-known disease of the liver in adults and children throughout the world. The main manifestations related to NAFLD are an unusual storage of lipid in hepatocytes (hepatic steatosis) and progression of inflammation for non-alcoholic steatohepatitis (NASH). NAFLD is described as a multifactorial complication due to the genetic predisposition, metabolic functions, inflammatory, gut microbiota (GM), and environmental factors. The GM dysregulation among these factors is correlated to NAFLD development. In recent decades, advanced microbial profiling methods are continuing to shed light on the nature of the changes in the GM caused by NASH and NAFLD. In the current review, we aim to perform a literature review in different library databases and electronic searches (Science Direct, PubMed, and Google Scholar) which were randomly obtained. This will be done in order to provide an overview of the relation between GM and NAFLD, and the role of prebiotics, probiotics, and fecal microbiota transplantation (FMT), as potential therapeutic challenges for NAFLD.

Effects of combined therapy with resveratrol, continuous and interval exercises on apoptosis, oxidative stress, and inflammatory biomarkers in the liver of old rats with non-alcoholic fatty liver disease

CONTEXT

Non-alcoholic fatty liver disease (NAFLD) is the most common chronic liver disorder.

OBJECTIVE

Effects of combined therapy with resveratrol, interval and continuous exercises on oxidative stress, inflammation, and apoptosis in the liver of rats with NAFLD.

METHODS

NAFLD rats were organised in patient, saline, resveratrol (RSV), continuous exercise, interval exercise, continuous exercise + RSV, and interval exercise + RSV groups.

RESULTS

Resveratrol supplementation alone or in combination with interval and continuous training significantly decreased malondialdehyde and TNF-α level (p < .05), while the levels of catalase; superoxide dismutase and IL-10 were significantly increased (p < .05). Although RSV alone significantly decreased the percentage of apoptotic cells (17.12%), its combination with interval (10.74%), and continuous (14.85%) exercise training demonstrated higher anti-apoptotic activity (p < .05).

CONCLUSIONS

Although resveratrol alone has an antioxidant, anti-apoptotic and anti-inflammatory properties, combined therapy with interval, and continuous training can be more effective to mitigate these abnormalities in NAFLD patients.

A two gene-based risk score predicts alcoholic cirrhosis development in males with at-risk alcohol consumption

Background

Alcoholic cirrhosis represents 1% of all cause-of-deaths worldwide. Its incidence is higher in males and results from the combination of environmental and genetic factors. Among all the genetic determinants of alcoholic cirrhosis, the patatin-like phospholipase domain protein 3 (PNPLA3) rs738409 represents the most widely validated determinant. Recent cross-sectional studies on alcohol abusers identified transmembrane-6 superfamily member 2 (TM6SF2) rs58542926, membrane bound O-acyltransferase domain containing 7 (MBOAT7) rs641738, and cluster of differentiation 14 (CD14) rs2569190 as new genetic risk factors for alcoholic cirrhosis. We aimed to develop a gene-based risk score to predict the incidence of alcoholic cirrhosis in males with at-risk alcohol consumption.

Materials and methods

A total of 416 male at-risk alcohol drinkers were retrospectively examined. The association between alcoholic cirrhosis incidence and PNPLA3, CD14, TM6SF2, and MBOAT7 variants was tested. Age at onset of at-risk alcohol consumption, age, and body mass index (BMI) were included as covariates to determine the prediction score for alcoholic cirrhosis incidence by evaluating time-dependent receiver operating characteristic curves.

Results

We found that PNPLA3, CD14, and TM6SF2 were associated with alcoholic cirrhosis prevalence. PNPLA3 and CD14 were also associated with its incidence. The best predictive score formula was (age at onset of at-risk alcohol consumption × 0.1) + (number of CD14 allele T) + (number of PNPLA3 allele M) + (BMI × 0.1). A threshold of 7.27 was identified as cutoff for the predictive risk of alcoholic cirrhosis development in 36 years from the onset of at-risk alcohol consumption with 70.1% sensitivity and 78.7% specificity.

Conclusion

We developed the first score for alcoholic cirrhosis prediction that combines clinical and genetic factors.

Alcohol or Not: A Review Comparing Initial Mechanisms, Contributing Factors, and Liver Transplantation Outcomes Between Alcoholic and Nonalcoholic Steatohepatitis

Chronic liver diseases take many forms; alcohol-related liver disease (ALD) and nonalcoholic fatty liver disease (NAFLD) are two common illnesses that potentially lead to cirrhosis, liver failure, and liver cancer. It is estimated that a quarter of heavy drinkers develop ALD and the same portion of people without heavy drinking habits have NAFLD. Alcohol intake is regularly used to differentiate NAFLD from ALD; however, diagnosis based on the discrimination threshold may be suboptimal when facing an obese patient with a high level of alcohol exposure. Therefore, understanding the common and/or different mechanism(s) driving each disease is extremely important. The ‘two-hit’ or ‘multi-hit’ hypothesis is used to explain the pathogenesis of both diseases. The ‘first hit’ refers to developing steatosis, the accumulation of fat components in the liver, and the ‘second hits’ are factors leading to oxidative stress, inflammation, and fibrosis, such as metabolic syndromes (e.g., morbid obesity, hyperglycaemia, hyperlipidaemia, disturbed circadian cycles, and altered intestinal microbiota) and environmental toxins (e.g., cigarette smoke and pollutants). Heritable factors also affect the probability and disease progression of both ALD and NAFLD. Whereas PNPLA3 and TM6SF2 variants are influential genetic risk factors for the diseases, epigenetic factors, such as DNA methylation, post-translational histone modifications, and small non-coding RNA, are of paramount importance. Moreover, considering that both ALD and NAFLD patients may eventually develop end-stage liver disease and require liver transplantation, the authors extensively investigated the worldwide outcomes from original literature for these two aetiologies, and the results showed no obvious differences in post-transplantation survival between them. Precise percentage determination of these two aetiologies contributing to steatohepatitis and its secondary injuries in the future would allow for better strategies for therapeutic and preventive intervention.

The Role of Long Non-Coding RNAs (lncRNAs) in the Development and Progression of Fibrosis Associated with Nonalcoholic Fatty Liver Disease (NAFLD)

Nonalcoholic fatty liver disease (NAFLD) encompasses a spectrum of conditions ranging from hepatic steatosis to inflammation (nonalcoholic steatohepatitis or NASH) with or without fibrosis, in the absence of significant alcohol consumption. The presence of fibrosis in NASH patients is associated with greater liver-related morbidity and mortality; however, the molecular mechanisms underlying the development of fibrosis and cirrhosis in NAFLD patients remain poorly understood. Long non-coding RNAs (lncRNAs) are emerging as key contributors to biological processes that are underpinning the initiation and progression of NAFLD fibrosis. This review summarizes the experimental findings that have been obtained to date in animal models of liver fibrosis and NAFLD patients with fibrosis. We also discuss the potential applicability of circulating lncRNAs to serve as biomarkers for the diagnosis and prognosis of NAFLD fibrosis. A better understanding of the role played by lncRNAs in NAFLD fibrosis is critical for the identification of novel therapeutic targets for drug development and improved, noninvasive methods for disease diagnosis.

Lean non-alcoholic fatty liver disease

BACKGROUND & AIMS

Non-alcoholic fatty liver disease (NAFLD), with its increasing prevalence and association with various co-morbidities, such as diabetes, cardiovascular disease and metabolic syndrome, is a growing concern. Previously thought to predominantly affect obese individuals, NAFLD has been shown to occur in non-obese subjects. This subset of individuals, known to have 'lean NAFLD' or 'non-obese NAFLD', is also growing increasingly prevalent. We summarize the clinical manifestations, pathophysiology and management of lean NAFLD in both adult and pediatric populations.

METHODS

Two reviewers performed an independent, formal review and analysis of the literature (PubMed and EMBASE search until April 2018).

RESULTS AND CONCLUSIONS

Patients with lean NAFLD share metabolic features of insulin resistance and dyslipidemia, similar to obese patients with NAFLD. Genetic predisposition, dietary and environmental factors may play a role in the pathogenesis of lean NAFLD. Genetic and metabolic conditions should be considered as well. Currently, there are no formal recommendations for the treatment of adult or pediatric lean NAFLD; however, lifestyle changes aimed at improving overall fitness are likely to have a favorable impact.

Transgenic expression of the RNA binding protein IMP2 stabilizes miRNA targets in murine microsteatosis

Adult expression of IMP2 is often associated with several types of disease and cancer. The RNA binding protein IMP2 binds and stabilizes the IGF2 mRNA as well as hundreds of other transcripts during development. To gain insight into the molecular action of IMP2 and its contribution to disease in context of adult cellular metabolism, we analyze transgenic overexpression of IMP2 in mouse livers, which has been shown to induce a steatosis-like phenotype and enhanced risk to develop hepatocellular carcinoma (HCC). Our data show up-regulation of several HCC marker genes and miRNAs (miR438-3p and miR151-5p). To characterize the impact of miRNAs to their targets, integrative analysis of transcriptome-and miRNAome-dynamics in combination with IMP2 target prediction was carried out. Our analyses show that targets of expressed miRNAs become accumulated in the case that these transcripts have positive IMP2 binding prediction. Therefore, our data indicates that overexpression of IMP2 alters the regulatory capacity of many miRNAs and we conclude that IMP2 competes with miRNAs for binding sites on thousands of transcripts. As a result, our data implicates that overexpression of IMP2 has distinct effects to the regulatory capacity of miRNAs with yet unknown consequences for translational efficiency.

MTP genetic variants associated with non-alcoholic fatty liver in metabolic syndrome patients

This study was performed for investigation the relationship between variants of MTP gene polymorphism and the development of NAFLD in patients with and without MS. The study was included 174 NAFLD patients (106 with MS and 68 without MS), and 141 healthy control subjects. The 493 G/T polymorphism of MTP gene was evaluated by PCR-RFLP method. The frequency of MTP TT genotype and T allele were significantly higher in NAFLD patients when compared to healthy controls. Moreover, a significant association in MTP gene polymorphism was observed in NAFLD patients with MS compared to NAFLD patients without MS and controls. Our study suggested that MTP 493 G/T gene polymorphism may act as susceptibility biomarker for NAFLD and MS.

Antioxidant Effect of Barley Sprout Extract via Enhancement of Nuclear Factor-Erythroid 2 Related Factor 2 Activity and Glutathione Synthesis

We previously showed that barley sprout extract (BSE) prevents chronic alcohol intake-induced liver injury in mice. BSE notably inhibited glutathione (GSH) depletion and increased inflammatory responses, revealing its mechanism of preventing alcohol-induced liver injury. In the present study we investigated whether the antioxidant effect of BSE involves enhancing nuclear factor-erythroid 2 related factor 2 (Nrf2) activity and GSH synthesis to inhibit alcohol-induced oxidative liver injury. Mice fed alcohol for four weeks exhibited significantly increased oxidative stress, evidenced by increased malondialdehyde (MDA) level and 4-hydroxynonenal (4-HNE) immunostaining in the liver, whereas treatment with BSE (100 mg/kg) prevented these effects. Similarly, exposure to BSE (0.1–1 mg/mL) significantly reduced oxidative cell death induced by t-butyl hydroperoxide (t-BHP, 300 μM) and stabilized the mitochondrial membrane potential (∆ψ). BSE dose-dependently increased the activity of Nrf2, a potential transcriptional regulator of antioxidant genes, in HepG2 cells. Therefore, increased expression of its target genes, heme oxygenase-1 (HO-1), NADPH quinone oxidoreductase 1 (NQO1), and glutamate-cysteine ligase catalytic subunit (GCLC) was observed. Since GCLC is involved in the rate-limiting step of GSH synthesis, BSE increased the GSH level and decreased both cysteine dioxygenase (CDO) expression and taurine level. Because cysteine is a substrate for both taurine and GSH synthesis, a decrease in CDO expression would further contribute to increased cysteine availability for GSH synthesis. In conclusion, BSE protected the liver cells from oxidative stress by activating Nrf2 and increasing GSH synthesis.

Decreasing CB1 receptor signaling in Kupffer cells improves insulin sensitivity in obese mice

Objective

Obesity-induced accumulation of ectopic fat in the liver is thought to contribute to the development of insulin resistance, and increased activity of hepatic CB₁R has been shown to promote both processes. However, lipid accumulation in liver can be experimentally dissociated from insulin resistance under certain conditions, suggesting the involvement of additional mechanisms. Obesity is also associated with pro-inflammatory changes which, in turn, can promote insulin resistance. Kupffer cells (KCs), the liver's resident macrophages, are the major source of pro-inflammatory cytokines in the liver, such as TNF-α, which has been shown to inhibit insulin signaling in multiple cell types, including hepatocytes. Here, we sought to identify the role of CB₁R in KCs in obesity-induced hepatic insulin resistance.

Methods

We used intravenously administered β-D-glucan-encapsulated siRNA to knock-down CB₁R gene expression selectively in KCs.

Results

We demonstrate that a robust knock-down of the expression of Cnr1, the gene encoding CB₁R, results in improved glucose tolerance and insulin sensitivity in diet-induced obese mice, without affecting hepatic lipid content or body weight. Moreover, Cnr1 knock-down in KCs was associated with a shift from pro-inflammatory M1 to anti-inflammatory M2 cytokine profile and improved insulin signaling as reflected by increased insulin-induced Akt phosphorylation.

Conclusion

These findings suggest that CB₁R expressed in KCs plays a critical role in obesity-related hepatic insulin resistance via a pro-inflammatory mechanism.

•

CB₁R signaling promotes hepatic insulin resistance by promoting hepatic steatosis and hepatic inflammation.

•

CB₁R knock-down in liver macrophages (Kupffer cells, KCs) improves global insulin resistance and glucose homeostasis.

•

CB₁R expressed in KCs play a critical role in hepatic insulin resistance independent of ectopic fat in the liver or adipose tissue inflammation.

Genetic polymorphism in CD14 gene, a co-receptor of TLR4 associated with non-alcoholic fatty liver disease

AIM

To evaluate the pathogenic role of toll-like receptor (TLR) gene polymorphisms in patients with non-alcoholic fatty liver disease (NAFLD).

METHODS

Two hundred and fifty subjects (NAFLD = 200, healthy volunteers = 50) underwent polymerase chain reaction and restriction fragment length polymorphism to assess one polymorphism in the toll-like receptor 2 (TLR2) gene (A753G), two polymorphisms in the TLR4 gene (TLR4 Asp299Gly and Thr399Ile allele), and two polymorphisms in the cluster of differentiation 14 (CD14) (C-159T and C-550T) gene, a co-receptor of TLR4. Association of TLR gene polymorphisms with NAFLD and its severity was evaluated by genetic models of association.

RESULTS

On both multiplicative and recessive models of gene polymorphism association, there was significant association of CD14 C (-159) T polymorphism with NAFLD; patients with TT genotype had a 2.6 fold increased risk of developing NAFLD in comparison to CC genotype. There was no association of TLR2 Arg753Gln, TLR4 Asp299Gly, Thr399Ile, and CD14 C (-550) T polymorphisms with NAFLD. None of the TLR gene polymorphisms had an association with histological severity of NAFLD.

CONCLUSION

Patients with CD14 C (-159) T gene polymorphism, a co-receptor of TLR4, have an increased risk of NAFLD development.

Non-alcoholic fatty liver disease and liver transplantation

Cirrhosis secondary to non-alcoholic steatohepatitis (NASH) is a common indication for liver transplant. In comparison to other cirrhotic patients, patients with NASH cirrhosis are more likely to be older and have the metabolic syndrome. Pre-transplant, patients require careful evaluation of cardiovascular risk. As the incidence of non-alcoholic fatty liver disease (NAFLD) is rising, a greater proportion of donor grafts have steatosis greater than 30%, which is associated with poor outcomes. Grafts with steatosis greater than 60% are unsuitable for transplant. Overall, post-transplant survival outcomes for patients with NASH cirrhosis are similar to those with cirrhosis without NASH. However, NASH cirrhosis is associated with a higher 30-day mortality, predominantly from an increase in cardiovascular events and infections. Following liver transplant, there is a significant risk of NASH recurrence, although this seldom results in allograft loss. Furthermore, a significant number of patients who had a liver transplant for other reasons develop NASH de novo. When patients with NASH cirrhosis are considered for transplant, one of the major challenges lies in identifying which patients are too high risk for surgery. This review aims to provide information to aid this decision making process, and to provide guidance on the peri-operative care strategies that can modify risk.

Effect of Lipopolysaccharide on the Progression of Non-Alcoholic Fatty Liver Disease in High Caloric Diet-Fed Mice

The incidence of non-alcoholic steatohepatitis (NASH) is increasing. Because gut microbiota have been highlighted as one of the key factors in the pathogenesis of metabolic syndrome, we investigated the involvement of the bacterial component in the progression of non-alcoholic fatty liver (NAFL) to NASH. C57BL/6 mice were fed with maintenance food (MF, groups A and B) or a high caloric diet (HCD, groups C and D) for 1 month. Mice were then divided into four groups: Groups A and C were inoculated with PBS, while groups B and D were inoculated with lipopolysaccharide (LPS) plus complete Freund's adjuvant (CFA). The inoculations were performed a total of 3 times over 3 months. At 6 months, while hepatic steatosis was observed in groups C and D, cellular infiltration and fibrosis were less evident in group C than in group D. Inflammatory cytokines were upregulated in groups B and D. 16S rRNA pyrosequencing of whole colon homogenates containing faeces showed that certain bacterial groups, such as Bacteroidaceae, Peptostreptococcaceae and Erysipelotrichaceae, were increased in groups C and D. Although loading of bacterial components (LPS) resulted in hepatic inflammation in both MF- and HCD-fed mice, HCD feeding was more crucial in the progression of NAFL during the triggering phase.

Susceptibility of Different Mouse Wild Type Strains to Develop Diet-Induced NAFLD/AFLD-Associated Liver Disease

Although non-alcoholic and alcoholic fatty liver disease have been intensively studied, concerning pathophysiological mechanisms are still incompletely understood. This may be due to the use of different animal models and resulting model-associated variation. Therefore, this study aimed to compare three frequently used wild type mouse strains in their susceptibility to develop diet-induced features of non-alcoholic/alcoholic fatty liver disease. Fatty liver disease associated clinical, biochemical, and histological features in C57BL/6, CD-1, and 129Sv WT mice were induced by (i) high-fat diet feeding, (ii) ethanol feeding only, and (iii) the combination of high-fat diet and ethanol feeding. Hepatic and subcutaneous adipose lipid profiles were compared in CD-1 and 129Sv mice. Additionally hepatic fatty acid composition was determined in 129Sv mice. In C57BL/6 mice dietary regimens resulted in heterogeneous hepatic responses, ranging from pronounced steatosis and inflammation to a lack of any features of fatty liver disease. Liver-related serum biochemistry showed high deviations within the regimen groups. CD-1 mice did not exhibit significant changes in metabolic and liver markers and developed no significant steatosis or inflammation as a response to dietary regimens. Although 129Sv mice showed no weight gain, this strain achieved most consistent features of fatty liver disease, apparent from concentration alterations of liver-related serum biochemistry as well as moderate steatosis and inflammation as a result of all dietary regimens. Furthermore, the hepatic lipid profile as well as the fatty acid composition of 129Sv mice were considerably altered, upon feeding the different dietary regimens. Accordingly, diet-induced non-alcoholic/alcoholic fatty liver disease is most consistently promoted in 129Sv mice compared to C57BL/6 and CD-1 mice. As a conclusion, this study demonstrates the importance of genetic background of used mouse strains for modeling diet-induced non-alcoholic/alcoholic fatty liver disease.

Diagnostic value of alcoholic liver disease (ALD)/nonalcoholic fatty liver disease (NAFLD) index combined with γ-glutamyl transferase in differentiating ALD and NAFLD

BACKGROUND/AIMS

This study aimed to verify the reliability of the alcoholic liver disease (ALD)/nonalcoholic fatty liver disease (NAFLD) index (ANI) for distinguishing ALD in patients with hepatic steatosis from NAFLD, and to investigate whether ANI combined with γ-glutamyl transferase (GGT) would enhance the accuracy of diagnosis in China.

METHODS

A hundred thirty-nine cases of fatty liver disease (FLD) were divided into two groups of ALD and NAFLD. The ANI was calculated with an online calculator. All indicators and ANI values were analyzed using statistical methods.

RESULTS

ANI was significantly higher in patients with ALD than in those with NAFLD (7.11 ± 5.77 vs. -3.09 ± 3.89, p < 0.001). With a cut-off value of -0.22, the sensitivity, specificity, and area under the receiver operating characteristic curve (AUROC) of diagnosed ALD cases was 87.1%, 92.5%, and 0.934 (95% confidence interval [CI], 0.879 to 0.969), respectively. The corresponding values for aspartate aminotransferase (AST)/alanine transaminase (ALT), mean corpuscular volume (MCV), and GGT were 75.29%, 72.94%, and 0.826 (95% CI, 0.752 to 0.885); 94.34%, 83.02%, and 0.814 (95% CI, 0.739 to 0.875) and 80.23%, 79.25%, and 0.815 (95% CI, 0.740 to 0.876), respectively. ANI AUROC was significantly higher than the AST/ALT, MCV, or GGT AUROCs (all p < 0.001), moreover, ANI showed better diagnostic performance. The combination of ANI and GGT showed a better AUROC than ANI alone (0.976 vs. 0.934, p = 0.016). The difference in AUROCs between AST/ALT, MCV, and GGT was not statistically significant (all p > 0.05).

CONCLUSIONS

ANI can help distinguish ALD from NAFLD with high accuracy; when ANI was combined with GGT, its effectiveness improved further.

Uric acid regulates hepatic steatosis and insulin resistance through the NLRP3 inflammasome-dependent mechanism

BACKGROUND & AIMS

Hyperuricemia significantly increases risk of non-alcoholic fatty liver disease (NAFLD) and insulin resistance. However, the mechanisms responsible for this association are as yet unclear. This study aimed to investigate the effects and underlying mechanisms of uric acid on development of NAFLD and insulin resistance.

METHODS

We initially analyzed the impact of uric acid on the development of hepatic steatosis and insulin resistance in mice and in two cell models, HepG2 and L02. Subsequently, we studied the role of the NOD-like receptor family pyrin domain containing 3 (NLRP3) inflammasome in uric acid-induced fat accumulation and insulin signaling impairment.

RESULTS

We found that uric acid directly induces hepatocyte fat accumulation, insulin resistance, and insulin signaling impairment both in vivo and in vitro. We also found that uric acid-induced NLRP3 inflammasome activation, whereas lowering uric acid by allopurinol inhibited NLRP3 inflammasome activation in a high fat diet mouse model of NAFLD. Moreover, knocking down NLRP3 expression significantly attenuated uric acid-induced fat accumulation both in HepG2 cells and L02 cells. Knocking down NLRP3 expression also rescued uric acid-induced insulin signaling impairment in both cell types.

CONCLUSIONS

Uric acid regulates hepatic steatosis and insulin resistance through the NLRP3 inflammasome. Uric acid may be a new therapeutic target for NAFLD and insulin resistance.

Targeting PCSK9 for therapeutic gains: Have we addressed all the concerns?

Proprotein Convertase Subtilisin/Kexin Type 9 (PCSK9) regulates the expression of low-density lipoprotein (LDL)-receptors, through reducing their recycling by binding to the receptor along with LDL and targeting it for lysosomal destruction. PCSK9 also enhances the degradation of very-low-density-lipoprotein receptor (VLDLR) and lipoprotein receptor-related protein 1 (LRP-1) in a LDL-receptor independent manner. This role in lipid homeostasis presents PCSK9 as an attractive target for the therapeutic management of familial hypercholesterolemia as well as other refractory dyslipidaemias. However, PCSK9 mediates multifarious functions independent of its role in lipid homeostasis, which can be grouped under "pleiotropic functions" of the protein. This includes PCSK9's role in: trafficking of epithelial sodium channel; hepatic regeneration; pancreatic integrity and glucose homeostasis; antiviral activity; antimalarial activity; regulation of different cell signalling pathways; cortical neural differentiation; neuronal apoptosis and Alzheimer's disease. The question that needs to be investigated in depth is "How will the pleotropic functions of PCSK9, be affected by the therapeutic intervention of the protease's LDL-receptor lowering activity?" In this review, we appraise the different lipid lowering strategies targeting PCSK9 in light of the protein's different pleiotropic functions. Additionally, we delineate the key areas that require further examination, to ensure the long-term safety of the above lipid-lowering strategies.

Celiac disease-related hepatic injury: Insights into associated conditions and underlying pathomechanisms

BACKGROUND

Celiac disease (CD) is the most common autoimmune enteropathy. Clinical manifestations may range from a typical malabsorption syndrome to several apparently unrelated extra-intestinal symptoms.

AIM

Here we specifically focus on the spectrum of CD-related liver disorders and the underlying pathomechanisms.

METHODS

A computer-based search up to August 2015 was completed using appropriate keywords. References from selected papers were also reviewed and used if relevant.

RESULTS

An unexplained hypertransaminasemia with nonspecific histologic hepatic changes is the most common hepatic presentation. CD however can coexist with a number of liver disorders such as Autoimmune Hepatitis, Autoimmune Cholangitis, Primary Biliary Cirrhosis and Primary Sclerosing Cholangitis requiring a specific treatment in addition to gluten-free diet. CD has also been associated with Viral Hepatitis, Fatty Liver, Non-Alcoholic Steatohepatitis and some severe cryptogenic hepatopaties in the liver transplantation list. Pathomechanisms underlying hepatic injury in CD are multiple, appear still not completely defined and may probably co-occur.

CONCLUSIONS

An ever-increasing number of CD-related liver injuries exist, probably representing a continuum of a same disorder where genetic predisposition, timing, and duration of previous gluten exposure might influence the reversibility of liver damage. Evidences, although not conclusive, support therefore testing for CD also in cryptogenic hepatobiliary conditions where the relationship with CD has not yet been fully investigated.

The Molecular Circadian Clock and Alcohol-Induced Liver Injury

Emerging evidence from both experimental animal studies and clinical human investigations demonstrates strong connections among circadian processes, alcohol use, and alcohol-induced tissue injury. Components of the circadian clock have been shown to influence the pathophysiological effects of alcohol. Conversely, alcohol may alter the expression of circadian clock genes and the rhythmic behavioral and metabolic processes they regulate. Therefore, we propose that alcohol-mediated disruption in circadian rhythms likely underpins many adverse health effects of alcohol that cut across multiple organ systems. In this review, we provide an overview of the circadian clock mechanism and showcase results from new studies in the alcohol field implicating the circadian clock as a key target of alcohol action and toxicity in the liver. We discuss various molecular events through which alcohol may work to negatively impact circadian clock-mediated processes in the liver, and contribute to tissue pathology. Illuminating the mechanistic connections between the circadian clock and alcohol will be critical to the development of new preventative and pharmacological treatments for alcohol use disorders and alcohol-mediated organ diseases.

Genome-wide analysis of hepatic lipid content in extreme obesity

AIMS

Individuals with type 2 diabetes have an increased risk of developing non-alcoholic fatty liver disease (NAFLD), and NAFLD patients are also at greater risk for developing type 2 diabetes. Although the relationship between type 2 diabetes and NAFLD is highly interconnected, the pathogenic mechanisms linking the two diseases are poorly understood. The goal of this study was to identify genetic determinants of hepatic lipid accumulation through association analysis using histological phenotypes in obese individuals.

METHODS

Using the Illumina HumanOmniExpress BeadChip assay, we genotyped 2,300 individuals on whom liver biopsy data were available.

RESULTS

We analyzed total bilirubin levels, which are linked to fatty liver in severe obesity, and observed the strongest evidence for association with rs4148325 in UGT1A (P < 5.0 × 10(-93)), replicating previous findings. We assessed hepatic fat level and found strong evidence for association with rs4823173, rs2896019, and rs2281135, all located in PNPLA3 and rs10401969 in SUGP1. Analysis of liver transcript levels of 20 genes residing at the SUGP1/NCAN locus identified a 1.6-fold change in the expression of the LPAR2 gene in fatty liver. We also observed suggestive evidence for association between low-grade fat accumulation and rs10859525 and rs1294908, located upstream from SOCS2 and RAMP3, respectively. SOCS2 was differentially expressed between fatty and normal liver.

CONCLUSIONS

These results replicate findings for several hepatic phenotypes in the setting of extreme obesity and implicate new loci that may play a role in the pathophysiology of hepatic lipid accumulation.

Dietary patterns are associated with prevalence of fatty liver disease in adults

BACKGROUND/OBJECTIVES

Previous studies have indicated that higher levels of food consumption are associated with fatty liver disease (FLD), but few studies have investigated the relationship between this disease and different dietary patterns. The aim of this cross-sectional study was to examine the association between dietary patterns and FLD in adults.

SUBJECTS/METHODS

Dietary intakes of participants in the Tianjin were assessed via questionnaire. Factor analysis was used to identify dietary patterns, and FLD was defined as having a FLD diagnosis using liver ultrasonography. Relationships between dietary patterns and FLD were assessed using multiple logistic regression analysis.

RESULTS

Female participants in the highest quartile of high-carbohydrate/sweet pattern scores had a 2.19-fold greater risk (95% confidence interval (CI), 1.40-3.46) of developing non-alcoholic FLD (NAFLD) than those in the lowest quartile after adjusting for confounding factors. No significant differences were found between any dietary pattern and NAFLD in males. In males, a significantly increasing trend of alcoholic FLD (AFLD) prevalence was associated with increasing high-protein/cholesterol pattern scores (P for trend = 0.03; odds ratio (OR), 2.08; 95% CI, 1.15-3.81) while an increased high-carbohydrate/sweet pattern score appeared protective against AFLD (P for trend = 0.02; OR, 0.55; 95% CI, 0.29-1.00).

CONCLUSIONS

Our study demonstrates that high-protein/cholesterol pattern scores are associated with higher prevalence of AFLD in males. We also show high-carbohydrate/sweet pattern scores are associated with higher prevalence of NAFLD in females; but, interestingly, this pattern shows a favorable effect on AFLD in males.

Pathological features of fatty liver disease

Alcoholic liver disease (ALD) and nonalcoholic fatty liver disease (NAFLD) are significant causes of chronic liver disease worldwide. Both are characterized by histological lesions that can include steatosis, and each can lead to cirrhosis. It might be possible for pathologists to identify lesions and patterns of ALD and NAFLD; we review these lesions and propose methods to distinguish between the disorders. Any form of ALD can lead to end-stage liver disease, according to long-term studies of biopsy specimens and patient outcomes. Although steatosis can be a significant cofactor in progression of established chronic liver disease, or even development of hepatocellular carcinoma, only steatohepatitis indicates the presence of progressive liver disease in patients with NAFLD. Pediatric and adolescent NAFLD differ from adult nonalcoholic steatohepatitis and should be recognized as distinct conditions. Benign and malignant liver tumors have been more frequently reported with the increasing prevalence of obesity and diabetes. Histological scoring systems for ALD and NAFLD have been proposed to monitor efficacy in clinical trials and serve as prognostic factors. We review what we have learned from pathological analyses about the development of these disorders and how this information might be used to detect and treat them.

The effect of dietary fat intake on hepatic gene expression in LG/J AND SM/J mice

Background

The liver plays a major role in regulating metabolic homeostasis and is vital for nutrient metabolism. Identifying the genetic factors regulating these processes could lead to a greater understanding of how liver function responds to a high-fat diet and how that response may influence susceptibilities to obesity and metabolic syndrome. In this study we examine differences in hepatic gene expression between the LG/J and SM/J inbred mouse strains and how gene expression in these strains is affected by high-fat diet. LG/J and SM/J are known to differ in their responses to a high-fat diet for a variety of obesity- and diabetes-related traits, with the SM/J strain exhibiting a stronger phenotypic response to diet.

Results

Dietary intake had a significant effect on gene expression in both inbred lines. Genes up-regulated by a high-fat diet were involved in biological processes such as lipid and carbohydrate metabolism; protein and amino acid metabolic processes were down regulated on a high-fat diet. A total of 259 unique transcripts exhibited a significant diet-by-strain interaction. These genes tended to be associated with immune function. In addition, genes involved in biochemical processes related to non-alcoholic fatty liver disease (NAFLD) manifested different responses to diet between the two strains. For most of these genes, SM/J had a stronger response to the high-fat diet than LG/J.

Conclusions

These data show that dietary fat impacts gene expression levels in SM/J relative to LG/J, with SM/J exhibiting a stronger response. This supports previous data showing that SM/J has a stronger phenotypic response to high-fat diet. Based upon these findings, we suggest that SM/J and its cross with the LG/J strain provide a good model for examining non-alcoholic fatty liver disease and its role in metabolic syndrome.

Host genetic variants in obesity-related nonalcoholic fatty liver disease

Nonalcoholic fatty liver disease (NAFLD) is a complex disease. The considerable variability in the natural history of the disease suggests an important role for genetic variants in the disease development and progression. There is evidence based on genome-wide association studies and/or candidate gene studies that genetic polymorphisms underlying insulin signaling, lipid metabolism, oxidative stress, fibrogenesis, and inflammation can predispose individuals to NAFLD. This review highlights some of the genetic variants in NAFLD.

Identification of novel clinical factors associated with hepatic fat accumulation in extreme obesity

OBJECTIVES

The accumulation of lipids stored as excess triglycerides in the liver (steatosis) is highly prevalent in obesity and has been associated with several clinical characteristics, but most studies have been based on relatively small sample sizes using a limited set of variables. We sought to identify clinical factors associated with liver fat accumulation in a large cohort of patients with extreme obesity.

METHODS

We analyzed 2929 patients undergoing intraoperative liver biopsy during a primary bariatric surgery. Univariate and multivariate regression modeling was used to identify associations with over 200 clinical variables with the presence of any fat in the liver and with moderate to severe versus mild fat accumulation.

RESULTS

A total of 19 data elements were associated with the presence of liver fat and 11 with severity of liver fat including ALT and AST, plasma lipid, glucose, and iron metabolism variables, several medications and laboratory measures, and sleep apnea. The accuracy of a multiple logistic regression model for presence of liver fat was 81% and for severity of liver fat accumulation was 77%.

CONCLUSIONS

A limited set of clinical factors can be used to model hepatic fat accumulation with moderate accuracy and may provide potential mechanistic insights in the setting of extreme obesity.

Non-alcoholic fatty liver disease and liver transplantation: Outcomes and advances

Non-alcoholic fatty liver disease (NAFLD) is one of the most prevalent causes of chronic liver disease worldwide. In the last decade it has become the third most common indication for liver transplantation in the United States. Increasing prevalence of NAFLD in the general population also poses a risk to organ donation, as allograft steatosis can be associated with non-function of the graft. Post-transplant survival is comparable between NAFLD and non-NAFLD causes of liver disease, although long term outcomes beyond 10 year are lacking. NAFLD can recur in the allograft frequently although thus far post transplant survival has not been impacted. De novo NAFLD can also occur in the allograft of patients transplanted for non-NAFLD liver disease. Predictors for NAFLD post-transplant recurrence include obesity, hyperlipidemia and diabetes as well as steroid dose after liver transplantation. A polymorphism in PNPLA3 that mediates triglyceride hydrolysis and is linked to pre-transplant risk of obesity and NAFLD has also been linked to post transplant NAFLD risk. Although immunosuppression side effects potentiate obesity and the metabolic syndrome, studies of immunosuppression modulation and trials of specific immunosuppression regimens post-transplant are lacking in this patient population. Based on pre-transplant data, sustained weight loss through diet and exercise is the most effective therapy for NAFLD. Other agents occasionally utilized in NAFLD prior to transplantation include vitamin E and insulin-sensitizing agents. Studies of these therapies are lacking in the post-transplant population. A multimodality and multidisciplinary approach to treatment should be utilized in management of post-transplant NAFLD.

Protective effects of dioscin against alcohol-induced liver injury

Our previous studies have shown that dioscin has protective effect against liver injury. However, the action of the compound against ethanol-induced liver injury is still unknown. In the present paper, ethanol-induced acute and chronic liver damage rat models were used, and the results showed that dioscin significantly alleviated liver steatosis, reduced the levels of alanine aminotransferase, aspartate aminotransferase, total triglyceride (TG), total cholesterol and malondialdehyde, and increased the levels of high-density lipoprotein, superoxide dismutase, glutathione and glutathione peroxidase. Transmission electron microscopy and terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling assays showed that dioscin prevented mitochondrial ultrastructural alterations and apoptosis caused by ethanol. In addition, dioscin significantly inhibited ethanol-induced cytochrome P450 2E1 activation, down-regulated the levels of mitogen-activated protein kinases phosphorylation, inhibited the expressions of nuclear factor kappa B, glucose regulated protein 78, activating transcription factor 6 and alpha subunit of translation initiation factor 2 to attenuate oxidative damage, decreased the expressions of tumor necrosis factor alpha and interleukin-6, and down-regulated the expressions of apoptosis-related proteins including p53, caspase-3, caspase-9, poly (ADP-ribose)-polymerase and cytokeratin-18. Further investigation indicated that dioscin markedly increased the expressions of peroxisome proliferators-activated receptor α and its target genes including medium-chain acyl-CoA dehydrogenase, carnitine palmitoyl-CoA transferase I and acyl-CoA oxidase to advance fatty acid β-oxidation, up-regulated the expressions of acyl-CoA synthetase long-chain family member 1, acyl-CoA synthetase long-chain family member 5, alpha-aminoadipic semialdehyde dehydrogenase and acyl-CoA dehydrogenase to promote fatty acid metabolism, and down-regulated the expressions of glycerol-3-phosphate acyltransferase, diacylglycerol acyltransferase 1 and diacylglycerol acyltransferase 2 to accelerate TG synthesis. However, dioscin had no effects on the expressions of sterol regulatory element-binding protein-1c, fatty acid synthase, acetyl-CoA carboxylase 1 and stearoyl-CoA desaturase 1 associated with fatty acid synthesis. In conclusion, dioscin shows excellent protective effect against ethanol-induced liver injury through ameliorating ethanol-induced oxidative stress, mitochondrial function, inflammatory cytokine production, apoptosis and liver steatosis, which should be developed as a new drug for the treatment of ethanol-induced liver injury in the future.

Role of oxidative stress in the pathogenesis of alcohol-induced liver disease

Chronic alcohol consumption is a well-known risk factor for liver disease, which represents a major cause of morbidity and mortality worldwide. The pathological process of alcohol-induced liver disease is characterized by a broad spectrum of morphological changes ranging from steatosis with minimal injury to more advanced liver damage, including steato-hepatitis and fibrosis/cirrhosis. Experimental and clinical studies increasingly show that the oxidative damage induced by ethanol contribute in many ways to the pathogenesis of alcohol hepatotoxicity. This article describes the contribution of oxidative mechanisms to liver damage by alcohol.

Convergent mechanisms for dysregulation of mitochondrial quality control in metabolic disease: implications for mitochondrial therapeutics

Mitochondrial dysfunction is associated with a broad range of pathologies including diabetes, ethanol toxicity, metabolic syndrome and cardiac failure. It is now becoming clear that maintaining mitochondrial quality through a balance between biogenesis, reserve capacity and mitophagy is critical in determining the response to metabolic or xenobiotic stress. In diseases associated with metabolic stress, such as Type II diabetes and non-alcoholic and alcoholic steatosis, the mitochondria are subjected to multiple 'hits' such as hypoxia and oxidative and nitrative stress, which can overwhelm the mitochondrial quality control pathways. In addition, the underlying mitochondrial genetics that evolved to accommodate high-energy demand, low-calorie supply environments may now be maladapted to modern lifestyles (low-energy demand, high-calorie environments). The pro-oxidant and pro-inflammatory environment of a sedentary western lifestyle has been associated with modified redox cell signalling pathways such as steatosis, hypoxic signalling, inflammation and fibrosis. These data suggest that loss of mitochondrial quality control is intimately associated with the aberrant activation of redox cell signalling pathways under pathological conditions. In the present short review, we discuss evidence from alcoholic liver disease supporting this concept, the insights obtained from experimental models and the application of bioenergetic-based therapeutics in the context of maintaining mitochondrial quality.

Role of AMPK activation in oxidative cell damage: Implications for alcohol-induced liver disease

Chronic alcohol consumption is a well-known risk factor for liver disease. Progression of alcohol-induced liver disease (ALD) is a multifactorial process that involves a number of genetic, nutritional and environmental factors. Experimental and clinical studies increasingly show that oxidative damage induced by ethanol contributes in many ways to the pathogenesis of alcohol hepatoxicity. Oxidative stress appears to activate AMP-activated protein kinase (AMPK) signaling system, which has emerged in recent years as a kinase that controls the redox-state and mitochondrial function. This review focuses on the most recent insights concerning the activation of AMPK by reactive oxygen species (ROS), and describes recent evidences supporting the hypothesis that AMPK signaling pathways play an important role in promoting cell viability under conditions of oxidative stress, such as during alcohol exposure. We suggest that AMPK activation by ROS can promote cell survival by inducing autophagy, mitochondrial biogenesis and expression of genes involved in antioxidant defense. Hence, increased intracellular concentrations of ROS may represent a general mechanism for enhancement of AMPK-mediated cellular adaptation, including maintenance of redox homeostasis. On the other hand, AMPK inhibition in the liver by ethanol appears to play a key role in the development of steatosis induced by chronic alcohol consumption. Although more studies are needed to assess the functions of AMPK during oxidative stress, AMPK may be a possible therapeutic target in the particular case of alcohol-induced liver disease.

The C-681G polymorphism of the PPAR-γ gene is associated with susceptibility to non-alcoholic fatty liver disease

Non-alcoholic fatty liver disease (NAFLD) is defined as excessive accumulation of fatty acid in the liver, a common disease in the world. The research of single nucleotide polymorphisms (SNPs) provides a new approach for managing NAFLD. SNPs may increase or decrease the functions of the target genes and their encoding proteins. Peroxisome proliferator-activated receptor (PPAR) plays a key role in modulating metabolism of hepatic triglycerides and consequently magnitude of NAFLD. In this study, we investigated the effect of three SNPs in the PPAR-γ gene i.e. rs10865710 (C-681G), rs7649970 (C-689T) and rs1801282 (C34G, also termed Pro12Ala) on susceptibility to NAFLD. The participants were selected from our epidemiological survey. Totally 169 participants were enrolled in NAFLD group, and 699 healthy subjects were included as controls. PCR-RFLP was applied to detect the SNPs. The G allele frequency of rs10865710 in NAFLD group (41.1%) was significantly higher than that (34.8%) in controls (p = 0.03). Differences in other two loci (rs7649970 and rs1801282) were not statistically significant between the two groups (p > 0.05). This result was confirmed by haplotype analysis. The GCC haplotype (a set of 3 adjacent SNPs in linkage disequilibrium, corresponding to the three alleles of above polymorphisms in order) was a risk factor for the susceptibility to NAFLD (p = 0.03). This study has revealed that the G allele of rs10865710 in the PPAR-γ gene is associated with the increased susceptibility to NAFLD. Our findings may provide novel diagnostic biomarkers and therapeutic targets for NAFLD.

A pathogenetic link between non-alcoholic fatty liver disease and celiac disease

Non-alcoholic fatty liver disease (NAFLD) has recently been recognized as the leading cause of the abnormalities in the liver function tests in the Western countries. Celiac disease (CD) is a permanent immunological intolerance to gluten proteins in genetically predisposed individuals. CD has been reported in 4-13 % of the cases with steatohepatitis, although the pathogenesis of the liver steatosis in CD patients is unclear. Based on the literature data, it can be concluded that the inclusion of serological markers of CD should be a part of the general workup in the patients with steatosis when other causes of the liver disease are excluded and in the patients with NAFLD when metabolic risk factors are not evident.

Influence of age and gender before and after liver transplantation

Women constitute a particular group among patients with chronic liver disease and in the post-liver transplantation (LT) setting: they are set apart not only by traditional differences with respect to men (ie, body mass index, different etiologies of liver disease, and accessibility to transplantation) but also in increasingly evident ways related to hormonal changes that characterize first the fertile age and subsequently the postmenopausal period (eg, disease course variability and responses to therapy). The aim of this review is, therefore, to evaluate the role of the interplay of factors such as age, gender, and hormones in influencing the natural history of chronic liver disease before and after LT and their importance in determining outcomes after LT. As the population requiring LT ages and the mean age at transplantation increases, older females are being considered for transplantation. Older patients are at greater risk for nonalcoholic steatohepatitis, osteoporosis, and a worse response to antiviral therapy. Female gender per se is associated with a greater risk for osteoporosis because of metabolic changes after menopause, the bodily structure of females, and, in the population of patients with chronic liver disease, the greater prevalence of cholestatic and autoimmune liver diseases. With menopause, the fall of protective estrogen levels can lead to increased fibrosis progression, and this represents a negative turning point for women with chronic liver disease and especially for patients with hepatitis C. Therefore, the notion of gender as a binary female/male factor is now giving way to the awareness of more complex disease processes within the female gender that follow hormonal, social, and age patterns and need to be addressed directly and specifically.

Genetics of nonalcoholic Fatty liver disease: an overview

Nonalcoholic fatty liver disease (NAFLD) is the most common liver disease in the world today. Its incidence in adults and children is rising rapidly due to the ongoing epidemics of obesity and type 2 diabetes. Hence, it has become a global public health issue. Environmental factors have been found to play a major role in the etiology of NAFLD, especially for genetically susceptible populations. Among these, one of the most important factors is junk food, especially the typical "Western-style" diet rich in simple carbohydrates, saturated fat, and highly processed food materials. Genetic predisposition to NAFLD does occur; however, a precise definition of genetic factors responsible for NAFLD is still lacking. Specific variants of different genes have been shown to present a risk for NAFLD. Genetic studies might be helpful in the management of the disease by developing novel treatment strategies based on individual's genotype.

Long-term management of alcoholic liver disease

Alcoholic liver disease is a major cause of morbidity and mortality worldwide. Patients with cirrhosis caused by alcohol are at risk for developing complications associated with a failing liver. The long-term management of alcoholic liver disease stresses the following: (1) Abstinence of alcohol (Grade 1A), with referral to an alcoholic rehabilitation program; (2) Adequate nutritional support (Grade 1B), emphasizing multiple feedings and a referral to a nutritionist; (3) Routine screening in alcoholic cirrhosis to prevent complications; (4) Timely referral to a liver transplant program for those with decompensated cirrhosis; (5) Avoid pharmacologic therapies, as these medications have shown no benefit.

p53/p66Shc-mediated signaling contributes to the progression of non-alcoholic steatohepatitis in humans and mice

BACKGROUND & AIMS

The tumor suppressor p53 is a primary sensor of stressful stimuli, controlling a number of biologic processes. The aim of our study was to examine the roles of p53 in non-alcoholic steatohepatitis (NASH).

METHODS

Male wild type and p53-deficient mice were fed a methionine- and choline-deficient diet for 8 weeks to induce nutritional steatohepatitis. mRNA expression profiles in normal liver samples and liver samples from patients with non-alcoholic liver disease (NAFLD) were also evaluated.

RESULTS

Hepatic p53 and p66Shc signaling was enhanced in the mouse NASH model. p53 deficiency suppressed the enhanced p66Shc signaling, decreased hepatic lipid peroxidation and the number of apoptotic hepatocytes, and ameliorated progression of nutritional steatohepatitis. In primary cultured hepatocytes, transforming growth factor (TGF)-β treatment increased p53 and p66Shc signaling, leading to exaggerated reactive oxygen species (ROS) accumulation and apoptosis. Deficient p53 signaling inhibited TGF-β-induced p66Shc signaling, ROS accumulation, and hepatocyte apoptosis. Furthermore, expression levels of p53, p21, and p66Shc were significantly elevated in human NAFLD liver samples, compared with results obtained with normal liver samples. Among NAFLD patients, those with NASH had significantly higher hepatic expression levels of p53, p21, and p66Shc compared with the group with simple steatosis. A significant correlation between expression levels of p53 and p66Shc was observed.

CONCLUSIONS

p53 in hepatocytes regulates steatohepatitis progression by controlling p66Shc signaling, ROS levels, and apoptosis, all of which may be regulated by TGF-β. Moreover, p53/p66Shc signaling in the liver appears to be a promising target for the treatment of NASH.

Resveratrol up-regulates hepatic uncoupling protein 2 and prevents development of nonalcoholic fatty liver disease in rats fed a high-fat diet

Obesity is associated with a markedly increased risk of nonalcoholic fatty liver disease. The anti-inflammatory polyphenol resveratrol possess promising properties in preventing this metabolic condition by dampening the pathological inflammatory reaction in the hepatic tissue. However, in the current study, we hypothesize that the beneficial effect of resveratrol is not solely attributable to its anti-inflammatory potential. Eight-week-old male Wistar rats were randomly distributed into 3 groups of 12 animals each: control diet (C), high-fat diet (HF), and HF supplemented with 100 mg resveratrol daily (HFR). After 8 weeks of dietary treatment, the rats were euthanized and relevant tissues were prepared for subsequent analysis. Resveratrol prevented the high fat-induced steatosis assessed by semiquantitative grading, which furthermore corresponded with a complete normalization of the hepatic triglyceride content (P < .001), despite no change in total body fat. In HFR, the hepatic uncoupling protein 2 expression was significantly increased by 76% and 298% as compared with HF and C, respectively. Moreover, the hepatic mitochondria content in HFR was significantly higher as compared with both C and HF (P < .001 and P = .004, respectively). We found no signs of hepatic inflammation, hereby demonstrating that resveratrol protects against fatty liver disease independently of its proposed anti-inflammatory potential. Our data might indicate that an increased number of mitochondria and, particularly, an increase in hepatic uncoupling protein 2 expression are involved in normalizing the hepatic fat content due to resveratrol supplementation in rodents fed a high-fat diet.

Polymorphisms of the CD14 genes are associated with susceptibility to alcoholic liver disease in Greek patients

BACKGROUND

The incidence and severity of alcoholic liver disease (ALD) in chronic drinkers has been found to correlate with some environmental factors and especially with the dose of alcohol consumption, but it is obvious that other parameters clearly contribute to individual alcohol susceptibility. Chronic ethanol exposure leads to continuous endotoxin-mediated Toll-like receptor-4 (TLR-4) and CD14 activation and subsequent cytokine release resulting in chronic inflammation with continued hepatocellular damage. Therefore, genetic studies of polymorphism in TLR-4 and CD14 genes seem to be appropriate in determining genetic susceptibility to ALD. Our aim is to evaluate in a series of Greek drinkers, the possible association of polymorphisms in the TLR-4 and CD14 genes with ALD.

METHODS

In 96 patients with ALD polymorphism of TLR-4 and CD14 genes were studied compared with 104 patients with cirrhosis of other etiology, 100 healthy subjects, and 50 patients with a history of alcohol abuse but without liver disease.

RESULTS

No association between ALD and the presence of the Asp299Gly and Thr399Ile polymorphisms in the TLR-4 gene could be documented in our patients. Regarding the CD14 -159 (C/T) genotypes, TT genotype and T allele were found to be overrepresented in alcoholic patients compared with patients with nonalcohol-induced liver disease and healthy controls. On the other side, when compared patients with ALD and patients with alcohol abuse and no liver disease, TT genotype was found to be significantly less frequent. There is no statistically significant association with the presence of the T allele and the severity of ALD, suggesting that CD14 polymorphism does not influence disease severity in advanced stages of the disease.

CONCLUSIONS

In our series in Greek patients with alcohol abuse and alcoholic cirrhosis, a significant negative association with the CD14 endotoxin receptor gene polymorphism (TT genotype) but not with the TLR-4 gene polymorphism was documented.

VSL#3 resets insulin signaling and protects against NASH and atherosclerosis in a model of genetic dyslipidemia and intestinal inflammation

BACKGROUND

Signals generated by the inflammed intestine are thought to contribute to metabolic derangement. The intestinal microbiota contributes to instructing the immune system beyond the intestinal wall and its modulation is a potential target for treating systemic disorders.

AIMS

To investigate the pathogenetic role of low grade intestinal inflammation in the development of steatohepatitis and atherosclerosis in a model of genetic dyslipidemia and to test the therapeutic potential of a probiotics intervention in protecting against development of these disorders.

RESULTS

ApoE(-/-) mice were randomized to receive vehicle or VSL#3, a mixture of eight probiotics, at the dose of 20×10(9) colony-forming units/kg/day for three months alone or in combination with 0.2% of dextran sulfate sodium (DSS) in drinking water. Administering DSS to ApoE(-/-) mice failed to induce signs and symptoms of colitis but increased intestinal permeability to dextran FITC and, while had no effect on serum lipids, increased the blood levels of markers of liver injury and insulin resistance. DSS administration associated with low level inflammation of intestinal and mesenteric adipose tissues, caused liver histopathology features of steatohepatitis and severe atherosclerotic lesions in the aorta. These changes were prevented by VSL#3 intervention. Specifically, VSL#3 reversed insulin resistance, prevented development of histologic features of mesenteric adipose tissue inflammation, steatohepatitis and reduced the extent of aortic plaques. Conditioned media obtained from cultured probiotics caused the direct transactivation of peroxisome proliferator-activated receptor-γ, Farnesoid-X-receptors and vitamin D receptor.

CONCLUSIONS

Low grade intestinal inflammation drives a transition from steatosis to steatohepatitis and worsens the severity of atherosclerosis in a genetic model of dyslipidemia. VSL#3 intervention modulates the expression of nuclear receptors, corrects for insulin resistance in liver and adipose tissues and protects against development of steatohepatitis and atherosclerosis.