The metabolic syndrome: how it may influence hepatic stellate cell activation and hepatic fibrosis

Tenofovir alafenamide significantly increased serum lipid levels compared with entecavir therapy in chronic hepatitis B virus patients

BACKGROUND

Tenofovir alafenamide (TAF) has a serum lipid-raising effect in patients with HIV; however, its effect on serum lipids and nonalcoholic fatty liver disease (NAFLD) risk in patients with chronic hepatitis B (CHB) is unclear.

AIM

To compare the effects of TAF and entecavir (ETV) on serum lipid levels in patients with CHB.

METHODS

In this retrospective cohort study, the data including the clinical features, serum lipids, and metabolic factors of patients with CHB at baseline and approximately 1 year after TAF or ETV treatment were collected and analyzed. We used propensity score-matched models to assess the effects on high-density lipoprotein, low-density lipoprotein, triglycerides, and total cholesterol (TCHO).

RESULTS

A total of 336 patients (75.60% male) were included; 63.69% received TAF and 36.31% received ETV. Compared with the ETV group, the TAF group had significantly higher TCHO levels after treatment (4.67 ± 0.90 vs 4.36 ± 1.05, P = 0.006). In a propensity score-matched model for body mass index, age, sex, smoking, drinking, presence of comorbidities such as NAFLD, cirrhosis, diabetes mellitus, and hypertension, TAF-treated patients had significantly increased TCHO levels compared to that at baseline (P = 0.019). There was no difference for the ETV group. Body mass index, sex, hypertension, baseline TCHO, and creatine kinase-MB isoenzyme levels were significantly associated with elevated TCHO levels in logistic regression analysis. However, 1-year TAF treatment did not increase the incidence of NAFLD.

CONCLUSION

A greater increase in TCHO was observed in patients with CHB receiving TAF compared to those receiving ETV. However, TAF-induced dyslipidemia did not increase the incidence of NAFLD.

A novel non-invasive model for the prediction of advanced liver fibrosis in chronic hepatitis B patients with NAFLD

There are still lack of non-invasive models to evaluate liver fibrosis in chronic hepatitis B (CHB) patients with nonalcoholic fatty liver disease (NAFLD). We aimed to establish a predictive model for advanced fibrosis in these patients. A total of 504 treatment-naive CHB patients with NAFLD who underwent liver biopsy were enrolled and randomly divided into a training set (n = 336) and a validation set (n = 168). Receiver operating characteristic (ROC) curve was used to compare predicting accuracy for the different models. One hundred fifty-six patients (31.0%) had advanced fibrosis. In the training set, platelet, prothrombin time, type 2 diabetes, HBeAg positivity and globulin were significantly associated with advanced fibrosis by multivariable analysis. A predictive model namely PPDHG for advanced fibrosis was developed based on these parameters. The areas under the ROC curve (AUROC) of PPDHG with an optimal cut-off value of -0.980 in predicting advanced fibrosis was 0.817 (95% confidence interval 0.772 to 0.862), with a sensitivity of 81.82% and a specificity of 66.81%. The predicting accuracy of PPDHG for advanced fibrosis was significantly superior to AST to platelet ratio index (APRI), fibrosis-4 score (FIB-4) and NAFLD fibrosis score (NFS). Further analysis revealed that the AUROC of PPDHG remained significantly higher than FIB-4 and NFS indexes, while it was comparable with APRI for predicting advanced fibrosis in the validation set. PPDHG had a better predicting performance than established models for advanced fibrosis in CHB patients with NAFLD. The application of PPDHG can reduce the necessary for liver biopsy in these patients.

Targeting the Gut Microbiome to Treat Metabolic Dysfunction-Associated Fatty Liver Disease: Ready for Prime Time?

Numerous studies show a modification of the gut microbiota in patients with obesity or diabetes. Animal studies have also shown a causal role of gut microbiota in liver metabolic disorders including steatosis whereas the human situation is less clear. Patients with metabolic dysfunction associated fatty liver disease (MAFLD) also have a modification in their gut microbiota composition but the changes are not fully characterized. The absence of consensus on a precise signature is probably due to disease heterogeneity, possible concomitant medications and different selection or evaluation criteria. The most consistent changes were increased relative abundance of Proteobacteria, Enterobacteriaceae and Escherichia species and decreased abundance of Coprococcus and Eubacterium. Possible mechanisms linking the microbiota and MAFLD are increased intestinal permeability with translocation of microbial products into the portal circulation, but also changes in the bile acids and production of microbial metabolites such as ethanol, short chain fatty acids and amino acid derivatives able to modulate liver metabolism and inflammation. Several interventional studies exist that attempt to modulate liver disease by administering antibiotics, probiotics, prebiotics, synbiotics, postbiotics or fecal transplantation. In conclusion, there are both gaps and hopes concerning the interest of gut microbiome evaluation for diagnosis purposes of MAFLD and for new therapeutic developments that are often tested on small size cohorts.

The Role of Metabolic Factors and Steatosis in Treatment-Naïve Patients with Chronic Hepatitis B and Normal Alanine Aminotransferase

Introduction

We aimed to elucidate the impact of metabolic syndrome (MS) and nonalcoholic fatty liver disease (NAFLD) on treatment-naïve patients with chronic hepatitis B (CHB) and normal alanine aminotransferase (ALT).

Methods

We analyzed the clinical characteristics of a cross-sectional cohort of treatment-naïve patients with CHB and ALT in the upper limit of normal (ULN) from October 2018 to July 2021. ALT ≤ 0.5 ULN was stratified as low-normal ALT (LNALT) and 0.5 ULN < ALT ≤ ULN as high-normal ALT (HNALT). Transient elastography (TE) was used to evaluate liver steatosis and fibrosis.

Results

Among 733 patients with CHB enrolled, 23.1% of them had MS, 37.2% of them had NAFLD, and 5.9% of them had significant fibrosis. The proportions of patients with MS, steatosis, and significant fibrosis in the HNALT group were higher than those in the LNALT group (31.4% vs. 14.1%, p < 0.001; 48.7% vs. 25.2%, p < 0.001; and 8.0% vs. 3.6%, p = 0.013, respectively). Multiple linear regression showed that steatosis (beta = 0.098, p = 0.001) and MS (beta = 0.092, p = 0.002) were independently related to ALT levels in the normal range. Multivariate logistic regression showed that age (OR 1.049, 95% CI 1.012–1.087, p = 0.010), aspartate aminotransferase (AST) (OR 1.059, 95% CI 1.005–1.115, p = 0.030), and severe steatosis (OR 2.559, 95% CI 1.212–5.403, p = 0.014) were independently associated with significant fibrosis. When analyzed in the subgroup of CHB with NAFLD, age (OR 1.060, 95% CI 1.006–1.117, p = 0.029) and severe steatosis (OR 2.962, 95% CI 1.126–7.792, p = 0.028) were still statistically significant.

Conclusion

The accumulation of MS components exacerbated hepatic steatosis. Severe NAFLD was independently associated with significant fibrosis. This emphasizes the importance of screening for MS and NAFLD in patients with CHB and normal ALT, where a more active intervention may apply.

Supplementary Information

The online version contains supplementary material available at 10.1007/s40121-022-00629-5.

Hepatic Fibrosis and Steatosis in Metabolic Syndrome

Background

Metabolic syndrome (MetS) is a group of factors associated with increased risks of cardiovascular disease and overall mortality. Nonalcoholic fatty liver disease (NAFLD) is a common disorder that has been shown to cause hepatic steatosis and fibrosis. The relationship between NAFLD and MetS appears to be bidirectional, but very few studies have examined the role of MetS in hepatic steatosis and fibrosis. The present study investigated the relationships between MetS and its components and the severity of hepatic fibrosis and steatosis, and fibrosis independent of steatosis.

Methods

The study was a cross-sectional population-based survey of 4,678 National Health and Nutrition Examination Survey participants from 2017 to 2018 in the United States. Hepatic fibrosis and steatosis were measured using liver elastography. The MetS components were assessed using demographic, examination, laboratory, and self-reported data.

Results

Using survey-weighted population estimates, 26% of the population had steatosis, 7.5% had fibrosis, and 3.3% had fibrosis without steatosis. The adjusted odds ratio for any level of steatosis was 4.12 times higher (95% confidence interval [CI], 3.16-5.37) and any level of fibrosis was 3.34 times higher (95% CI, 2.26-4.94) among participants with MetS than those without. The adjusted odds ratio for fibrosis without steatosis is 2.67 times higher (95% CI, 1.47-4.87) among participants with MetS than those without.

Conclusion

The presence of MetS significantly increases the risk of hepatic fibrosis and steatosis, providing evidence for MetS to be considered an additional independent risk factor for hepatic fibrosis together with other known etiologies.

Correlation Between Liver Stiffness and Diastolic Function, Left Ventricular Hypertrophy, and Right Cardiac Function in Patients With Ejection Fraction Preserved Heart Failure

Objective: Ejection fraction preserved heart failure (HFpEF) is a common clinical syndrome with a high morbidity, accounting for ~50% of all heart failure patients, and a mortality comparable to that of ejection fraction reduced heart failure (HFrEF). The relationship between liver stiffness (LS) and HFpEF remains unclear. The purpose of this study was to explore the correlation between LS and the severity of HFpEF.

Methods: We performed a prospective observational study. After accepting liver transient elastography on admission, consecutive 150 hospitalized HFpEF patients were divided into three groups based on their liver elasticity value: first-third quartiles. Left ventricular diastolic function, left ventricular hypertrophy degree, right cardiac function and short-term prognosis (≤1 year) were compared among the three groups, and the correlation between liver elasticity and each indicator was analyzed.

Results: The elasticity of the liver was abnormally high in more than two-thirds of cases. The proportion of NYHA class III-IV in the third quartile group was significantly higher than that in the first quartile group (96 vs. 70%, P = 0.013). Significant differences were discovered in the level of lgNT-proBNP between the three groups (2.63 ± 0.65 vs. 2.84 ± 0.44 vs. 3.05 ± 0.71, P = 0.027). In terms of diastolic function and left ventricular hypertrophy, the ventricular septal e′ (5.01 ± 2.69 vs. 6.48 ± 2.29, P = 0.025), lateral wall e′ (6.63 ± 3.50 vs. 8.62 ± 2.73, P = 0.013), mean E/e′ (20.06 ± 7.53 vs. 13.20 ± 6.05, P = 0.001), left atrial volume index (43.53 ± 10.94 vs. 35.78 ± 13.86, P = 0.008), tricuspid regurgitation (TR) peak flow rate (3.16 ± 0.44 vs. 2.75 ± 0.50, P < 0.001), left ventricular mass index (LVMI) in male (163.2 ± 47.6 vs. 131.3 ± 38.0, P = 0.015) and in female (147.4 ± 48.6 vs. 110.6 ± 24.3, P = 0.036) was significantly different between the third quartile and the first quartile. The proportion of patients with diastolic dysfunction in the third quartile was significantly higher than that in the first quartile (70 vs. 36%, P = 0.017). In terms of right cardiac function, right ventricular fractional area change (RVFAC) (30.3 ± 5.4 vs. 36.5 ± 6.8, P < 0.001), tricuspid annular plane systolic excursion (TAPSE) (7.7 ± 5.2 vs. 14.8 ± 5.9, P = 0.010), pulmonary systolic pressure (38.0 ± 10.5 vs. 32.4 ± 10.3, P = 0.005), TR peak flow rate (3.16 ± 0.44 vs. 2.75 ± 0.50, P < 0.001), and inferior vena cava diameter (2.53 ± 0.51 vs. 1.98 ± 0.41, P < 0.001) were significantly different between the third quartile and the first quartile. More than half of HFpEF patients were combined with right ventricular dysfunction (RVD). Compared to HFpEF without RVD, HFpEF with RVD had higher male sex (53.6 vs. 30.3%, P < 0.001), higher NYHA class (3.2 ± 0.6 vs. 2.8 ± 0.6, P = 0.010), higher proportion of atrial fibrillation (45.2 vs. 18.2%, P < 0.001), and higher liver elasticity value (7.95 ± 0.60 vs. 7.31 ± 0.84, P = 0.003). In terms of short-term prognosis, the incidence of adverse cardiovascular events was significantly higher in the third quartile than in the first quartile (P = 0.003) and the second quartile (P = 0.008). Multivariate Cox proportional hazard analysis showed that adverse cardiovascular events were independently associated with NYHA class, atrial fibrillation, lgNT-proBNP and liver elasticity value (HR = 1.208, 95% CI 1.115–1.352, P = 0.002).

Conclusion: Increase of liver stiffness is common in HFpEF patients. Increased LS in HFpEF patients was significantly associated with worsen left diastolic function, left ventricular hypertrophy, and the right cardiac function. LS in HFpEF patients may be more than the result of right ventricular dysfunction. Male, atrial fibrillation, poorer NYHA class and increased liver elasticity value were significantly associated with HFpEF combined with RVD. Atrial fibrillation, poorer NYHA class, higher NT-proBNP, and increased liver elasticity value were independent predictors of poor short-term prognosis of HFpEF patients.

Advanced Liver Fibrosis Is Associated with Necroinflammatory Grade but Not Hepatic Steatosis in Chronic Hepatitis B Patients

BACKGROUND AND AIMS

Patients with chronic hepatitis B (CHB) are at an increased risk of disease progression. The influence of hepatic steatosis (HS) to liver fibrosis was controversial. We aim to investigate the association between HS and liver fibrosis and explore the predicting factors for advanced fibrosis.

METHODS

CHB patients undergoing liver biopsy with complete assessments of HS, necroinflammation grade [histological activity index (HAI) score], and fibrosis stage were retrospectively recruited. Logistic regression analysis was performed to determine the factors associated with advanced liver fibrosis.

RESULTS

In this cohort of 672 patients, 342 (50.9%) had HS and 267 (39.4%) were of advanced liver fibrosis. Age [odds ratio (OR) 1.026, 95% confidence interval (CI) 1.007-1.046, p = 0.008], body mass index (BMI, OR 1.091, 95% CI 1.026-1.159, p = 0.005), genotype (C vs. B) (OR 2.790, 95% CI 1.847-4.214, p < 0.001), platelet (OR 0.986, 95% CI 0.982-0.991, p < 0.001), and HAI score (OR 1.197, 95% CI 1.114-1.285, p < 0.001) were independent factors for advanced liver fibrosis in multivariate logistic regression analysis. HAI score was also a significantly associated factor for significant liver fibrosis in non-cirrhotic subpopulation (OR 1.578, 95% CI 1.375-1.810, p < 0.001). HS was not related to advanced/significant liver fibrosis in overall/non-cirrhotic population (p > 0.05).

CONCLUSIONS

Significant or advanced liver fibrosis is associated with grade of necroinflammation but not with HS in CHB patients.

Sexual Dimorphism of NAFLD in Adults. Focus on Clinical Aspects and Implications for Practice and Translational Research

Nonalcoholic fatty liver disease (NAFLD) embraces the clinico-pathological consequences of hepatic lipotoxicity and is a major public health problem globally. Sexual dimorphism is a definite feature of most human diseases but, under this aspect, NAFLD lags behind other medical fields. Here, we aim at summarizing and critically discussing the most prominent sex differences and gaps in NAFLD in humans, with emphasis on those aspects which are relevant for clinical practice and translational research. Sexual dimorphism of NAFLD is covered with references to the following areas: disease prevalence and risk factors, pathophysiology, comorbidities, natural course and complications. Finally, we also discuss selected gender differences and whether sex-specific lifestyle changes should be adopted to contrast NAFLD in men and women.

Overview of the Pathogenesis, Genetic, and Non-Invasive Clinical, Biochemical, and Scoring Methods in the Assessment of NAFLD

Nonalcoholic fatty liver disease (NAFLD) is the most prevalent chronic liver disease worldwide. It represents a range of disorders, including simple steatosis, nonalcoholic steatohepatitis (NASH), and liver cirrhosis, and its prevalence continues to rise. In some cases, hepatocellular carcinoma (HCC) may develop. The develop;ment of non-invasive diagnostic and screening tools is needed, in order to reduce the frequency of liver biopsies. The most promising methods are those able to exclude advanced fibrosis and quantify steatosis. In this study, new perspective markers for inflammation, oxidative stress, apoptosis, and fibrogenesis; emerging scoring models for detecting hepatic steatosis and fibrosis; and new genetic, epigenetic, and multiomic studies are discussed. As isolated biochemical parameters are not specific or sensitive enough to predict the presence of NASH and fibrosis, there is a tendency to use various markers and combine them into mathematical algorithms. Several predictive models and scoring systems have been developed. Current data suggests that panels of markers (NAFLD fibrosis score, Fib-4 score, BARD score, and others) are useful diagnostic modalities to minimize the number of liver biopsies. The review unveils pathophysiological aspects related to new trends in current non-invasive biochemical, genetic, and scoring methods, and provides insight into their diagnostic accuracies and suitability in clinical practice.

Ileal interposition surgery targets the hepatic TGF-β pathway, influencing gluconeogenesis and mitochondrial bioenergetics in the UCD-T2DM rat model of diabetes

Ileal interposition (IT) is a surgical procedure that increases the delivery of incompletely digested nutrients and biliary and pancreatic secretions to the distal intestinal mucosa. Here, we investigated the metabolic impact of this intervention in 2-mo-old prediabetic University of California, Davis type 2 diabetes mellitus rats by assessing liver gene expression at 1.5 mo post-IT surgery. Pathway analysis indicated decreased signaling via TGF-β/Smad (a family of proteins named mothers against decapentaplegic homologs), peroxisome proliferator-activated receptor (PPAR), and PI3K-Akt-AMPK-mechanistic target of rapamycin, likely targeting hepatic stellate cells because differentiation and activation of these cells is associated with decreased signaling via PPAR and TGF-β/Smad. IT surgery up-regulated the expression of genes involved in regulation of cholesterol and terpenoid syntheses and down-regulated those involved in glycerophospholipid metabolism [including cardiolipin (CL)], lipogenesis, and gluconeogenesis. Consistent with the down-regulation of the hepatic CL pathway, IT surgery produced a metabolic switch in liver, kidney cortex, and fat depots toward decreased mitochondrial fatty acid β-oxidation, the process required to fuel high energy-demanding pathways (e.g., gluconeogenesis and glyceroneogenesis), whereas opposite effects were observed in skeletal and cardiac muscles. This study demonstrates for the first time the presence of metabolic pathways that complement the effects of IT surgery to maximize its benefits and potentially identify similarly effective, durable, and less invasive therapeutic options for metabolic disease, including inhibitors of TGF-β signaling.-Hung, C., Napoli, E., Ross-Inta, C., Graham, J., Flores-Torres, A. L., Stanhope, K. L., Froment, P., Havel, P. J., Giulivi, C. Ileal interposition surgery targets the hepatic TGF-β pathway, influencing gluconeogenesis and mitochondrial bioenergetics in the UCD-T2DM rat model of diabetes.

Chronic Hyperglycaemia Induced Alterations of Hepatic Stellate Cells Differ from the Effect of TGFB1, and Point toward Metabolic Stress

The deleterious effect of hyperglycemia on the biology of the liver is supported by clinical evidence. It can promote the development of fatty liver, liver fibrosis, even liver cancer as complication of diabetes mellitus. As liver fibrosis is the consequence of hepatic stellate cell (HSC) activation, the questions were addressed whether alterations induced by high glucose concentration are directly related to TGFB1 effect, or other mechanisms are activated. In order to obtain information on the response of HSC for high glucose, LX-2 cells (an immortalized human HSC cell lineage) were cultured in 15.3 mM glucose containing medium for 21 days. The effect of glucose was compared to that of TGFB1. Our data revealed that chronic exposure of high glucose concentration initiated profound alteration of LX-2 cells and the effect is different from those observed upon interaction with TGFB1. Whereas TGFB1 induced the production of extracellular matrix proteins, high glucose exposure resulted in decreased MMP2 activity, retardation of type I collagen in the endoplasmic reticulum, with decreased pS6 expression, pointing to development of endoplasmic stress and sequestration of p21^CIP1/WAF1 in the cytoplasm which can promote the proliferation of LX2 cells.

Therapeutic Approaches to Nonalcoholic Fatty Liver Disease: Exercise Intervention and Related Mechanisms

Exercise training ameliorates nonalcoholic fatty liver disease (NAFLD) as well as obesity and metabolic syndrome. Although it is difficult to eliminate the effects of body weight reduction and increased energy expenditure-some pleiotropic effects of exercise training-a number of studies involving either aerobic exercise training or resistance training programs showed ameliorations in NAFLD that are independent of the improvements in obesity and insulin resistance. In vivo studies have identified effects of exercise training on the liver, which may help to explain the "direct" or "independent" effect of exercise training on NAFLD. Exercise training increases peroxisome proliferator-activated receptor gamma coactivator 1-alpha (PGC1α) expression, improves mitochondrial function and leads to reduced hepatic steatosis, inflammation, fibrosis, and tumor genesis. Crosstalk between the liver and adipose tissue, skeletal muscle and the microbiome is also a possible mechanism for the effect of exercise training on NAFLD. Although numerous studies have reported benefits of exercise training on NAFLD, the optimal duration and intensity of exercise for the prevention or treatment of NAFLD have not been established. Maintaining adherence of patients with NAFLD to exercise training regimes is another issue to be resolved. The use of comprehensive analytical approaches to identify biomarkers such as hepatokines that specifically reflect the effect of exercise training on liver functions might help to monitor the effect of exercise on NAFLD, and thereby improve adherence of these patients to exercise training. Exercise training is a robust approach for alleviating the pathogenesis of NAFLD, although further clinical and experimental studies are required.

Targeting Kupffer cells in non-alcoholic fatty liver disease/non-alcoholic steatohepatitis: Why and how?

Mechanisms for non-alcoholic steatohepatitis (NASH) development are under investigation in an era of increased prevalence of obesity and metabolic syndrome. Previous findings have pointed to the role of adipose tissue, adipose tissue macrophages and their secretory products in the development of a chronic inflammatory status inducing insulin resistance and a higher risk of liver steatosis called non-alcoholic fatty liver disease. The activation of resident macrophages [Kupffer cells (KC)] and the recruitment of blood derived monocytes/macrophages into the diseased liver have now been identified as key elements for disease initiation and progression. Those cells could be activated through gut flora modifications and an altered gut barrier function but also through the internalization of toxic lipid compounds in adjacent hepatocytes or in KC themselves. Due to the role of activated KC in insulin resistance, fibrosis development and inflammation amplification, they became a target in clinical trials. A shift towards an anti-inflammatory KC phenotype through peroxisome proliferator activator-receptorδ agonists, an inhibition of macrophage recruitment through anti-C-C chemokine receptor 2 action and a specific blocking of internalization of toxic lipoxidation or glycation compounds into KC by galectin-3 receptor inhibitors are now under investigation in human NASH.

Characteristics of nonalcoholic fatty liver disease induced in wistar rats following four different diets

BACKGROUND/OBJECTIVES

The prevalence of nonalcoholic fatty liver disease (NAFLD) has increased worldwide in parallel with overnutrition characterized by high-fat and high-carbohydrate intake. Our objective was to establish, in 16 weeks, a model of NAFLD in Wistar pathogen-free rats following four dietary types.

MATERIALS/METHODS

Forty (6 weeks old) healthy Wistar male rats, weighing an average of 150 g were randomly divided into four groups of ten and assigned a diet with the same quantity (15 g/rat/day), but with different composition. The moderate-fat (MF) group was fed a moderate-fat diet (31.5% fat and 50% carbohydrates), the high-fat (HF) group was fed a fat-rich diet (51% fat), the high-sucrose (HS) group and the high-fructose (HFr) group were fed a carbohydrate-rich diet (61%). The carbohydrate contents of the HS group was composed of 60.3% sucrose while that of the HFr group was composed of 59.3% fructose.

RESULTS

At week 16, the HF group had the highest percentage of cells enriched in fat (40%) and the highest weight and liver weight (P < 0.05). The HFr group showed significantly higher levels of serum triglycerides, alanine aminotransferase and adiponectin at week 16 as compared to week 1 (P < 0.05).

CONCLUSIONS

The 15 g/rat/day diet composed of 51% fat or 61% carbohydrates enriched mainly in fructose may induce characteristics of NAFLD in rats.

Adipocytokines and hepatic fibrosis

Obesity and metabolic syndrome pose significant risk for the progression of many types of chronic illness, including liver disease. Hormones released from adipocytes, adipocytokines, associated with obesity and metabolic syndrome, have been shown to control hepatic inflammation and fibrosis. Hepatic fibrosis is the final common pathway that can result in cirrhosis, and can ultimately require liver transplantation. Initially, two key adipocytokines, leptin and adiponectin, appeared to control many fundamental aspects of the cell and molecular biology related to hepatic fibrosis and its resolution. Leptin appears to act as a profibrogenic molecule, while adiponectin has strong-antifibrotic properties. In this review, we emphasize pertinent data associated with these and other recently discovered adipocytokines that may drive or halt the fibrogenic response in the liver.

Adipokines and proinflammatory cytokines, the key mediators in the pathogenesis of nonalcoholic fatty liver disease

Nonalcoholic fatty liver disease (NAFLD) is a condition in which excess fat accumulates in the liver of a patient with no history of alcohol abuse or other causes for secondary hepatic steatosis. The pathogenesis of NAFLD and nonalcoholic steatohepatitis (NASH) has not been fully elucidated. The “two-hit“ hypothesis is probably a too simplified model to elaborate complex pathogenetic events occurring in patients with NASH. It should be better regarded as a multiple step process, with accumulation of liver fat being the first step, followed by the development of necroinflammation and fibrosis. Adipose tissue, which has emerged as an endocrine organ with a key role in energy homeostasis, is responsive to both central and peripheral metabolic signals and is itself capable of secreting a number of proteins. These adipocyte-specific or enriched proteins, termed adipokines, have been shown to have a variety of local, peripheral, and central effects. In the current review, we explore the role of adipocytokines and proinflammatory cytokines in the pathogenesis of NAFLD. We particularly focus on adiponectin, leptin and ghrelin, with a brief mention of resistin, visfatin and retinol-binding protein 4 among adipokines, and tumor necrosis factor-α, interleukin (IL)-6, IL-1, and briefly IL-18 among proinflammatory cytokines. We update their role in NAFLD, as elucidated in experimental models and clinical practice.

Antibodies to probe endogenous G protein-coupled receptor heteromer expression, regulation, and function

Over the last decade an increasing number of studies have focused on the ability of G protein-coupled receptors to form heteromers and explored how receptor heteromerization modulates the binding, signaling and trafficking properties of individual receptors. Most of these studies were carried out in heterologous cells expressing epitope tagged receptors. Very little information is available about the in vivo physiological role of G protein-coupled receptor heteromers due to a lack of tools to detect their presence in endogenous tissue. Recent advances such as the generation of mouse models expressing fluorescently labeled receptors, of TAT based peptides that can disrupt a given heteromer pair, or of heteromer-selective antibodies that recognize the heteromer in endogenous tissue have begun to elucidate the physiological and pathological roles of receptor heteromers. In this review we have focused on heteromer-selective antibodies and describe how a subtractive immunization strategy can be successfully used to generate antibodies that selectively recognize a desired heteromer pair. We also describe the uses of these antibodies to detect the presence of heteromers, to study their properties in endogenous tissues, and to monitor changes in heteromer levels under pathological conditions. Together, these findings suggest that G protein-coupled receptor heteromers represent unique targets for the development of drugs with reduced side-effects.

Serum HBV surface antigen positivity is associated with low prevalence of metabolic syndrome in Korean adult men

Background

Metabolic syndrome has clinical implications for chronic liver disease, but the relationship between chronic hepatitis B and metabolic syndrome remains unclear. The aim of this study was to determine whether hepatitis B surface antigen (HBsAg) positivity is associated with metabolic syndrome.

Methods

Data were obtained from the Third Korean National Health and Nutrition Examination Survey (KNHANES). Participant sera were tested for HBsAg. Metabolic syndrome was defined according to the modified National Cholesterol Education Program Adult Treatment Panel III guidelines for Koreans.

Results

Of the 5108 participants, 209 (4.1%) tested positive for HBsAg, and 1364 (26.7%) were diagnosed with metabolic syndrome. The prevalence of metabolic syndrome was 23.4% in HBsAg-positive men, 31.5% in HBsAg-negative men, 18.6% in HBsAg-positive women, and 23.7% in HBsAg-negative women. After adjusting for multiple factors, male participants who tested positive for serum HBsAg had an odds ratio of 0.612 (95% confidence interval [CI] 0.375–0.998) for metabolic syndrome and an odds ratio of 0.631 (95% CI 0.404–0.986) for elevated triglycerides. Women who tested positive for serum HBsAg had an odds ratio of 0.343 (95% CI 0.170–0.693) for elevated triglycerides.

Conclusions

Positive results for serum HBsAg are inversely associated with metabolic syndrome in men and with elevated triglycerides in men and women. This suggests that elevated triglycerides may contribute to the inverse association between HBsAg and metabolic syndrome.

Relationship between disease severity, hyperinsulinemia, and impaired insulin clearance in patients with nonalcoholic steatohepatitis

Hyperinsulinemia is believed to play a key role in the pathogenesis of nonalcoholic steatohepatitis (NASH) and associated cardiovascular risk. However, the relative contribution of insulin clearance to hyperinsulinemia and its relationship to liver histology have not been carefully evaluated before. To examine this, we enrolled 190 patients (32 without nonalcoholic fatty liver disease [NAFLD], 36 with simple steatosis [SS], and 122 with biopsy-proven NASH). Insulin secretion and hepatic insulin clearance were estimated by means of an oral glucose tolerance test, whereas peripheral insulin sensitivity and whole-body insulin clearance were measured during a euglycemic insulin clamp. A liver biopsy was performed to assess histology (grade/stage). Patients with NASH had similar hepatic insulin sensitivity, compared to patients with SS, but more severe adipose tissue insulin resistance and worse hyperinsulinemia. Patients with SS and NASH had a similar ∼30% reduction (P<0.01) in hepatic insulin clearance, when compared to patients without NAFLD. Reduced hepatic insulin clearance was not associated with severity of inflammation, ballooning, and fibrosis. In contrast, worse histological inflammation and ballooning (but not steatosis or fibrosis) were associated with a progressive reduction in whole-body insulin clearance (P<0.001 for trend). There was no significant difference in insulin secretion between patients with SS versus NASH.

CONCLUSION

Decreased hepatic insulin clearance develops with a mild increase in liver fat (LFAT) accumulation. It appears to be largely driven by hepatic steatosis, whereas steatohepatitis is more closely associated with reduced whole-body insulin clearance. Hyperinsulinemia in NAFLD correlated strongly with impaired insulin clearance, but not with insulin secretion. Strategies that reduce LFAT and improve insulin clearance hold the potential to revert the unfavorable effects of hyperinsulinemia in these patients.

Pathophysiology of NASH: perspectives for a targeted treatment

Non alcoholic steatohepatitis (NASH) is the more severe form of nonalcoholic fatty liver disease. In NASH, fatty liver, hepatic inflammation, hepatocyte injury and fibrogenesis are associated, and this condition may eventually lead to cirrhosis. Current treatment of NASH relies on the reduction of body weight and increase in physical activity, but there is no pharmacologic treatment approved as yet. Emerging data indicate that NASH progression results from parallel events originating from the liver as well as from the adipose tissue, the gut and the gastrointestinal tract. Thus, dysfunction of the adipose tissue through enhanced flow of free fatty acids and release of adipocytokines, and alterations in the gut microbiome generate proinflammatory signals that underlie NASH progression. Additional 'extrahepatic hits' include dietary factors and gastrointestinal hormones. Within the liver, hepatocyte apoptosis, ER stress and oxidative stress are key contributors to hepatocellular injury. In addition, lipotoxic mediators and danger signals activate Kupffer cells which initiate and perpetuate the inflammatory response by releasing inflammatory mediators that contribute to inflammatory cell recruitment and development of fibrosis. Inflammatory and fibrogenic mediators include chemokines, the cannabinoid system, the inflammasome and activation of pattern-recognition receptors. Here we review the major mechanisms leading to appearance and progression of NASH, focusing on both extrahepatic signals and local inflammatory mechanisms, in an effort to identify the most promising molecular targets for the treatment of this condition.

Pathophysiology of NASH: perspectives for a targeted treatment

Non alcoholic steatohepatitis (NASH) is the more severe form of nonalcoholic fatty liver disease. In NASH, fatty liver, hepatic inflammation, hepatocyte injury and fibrogenesis are associated, and this condition may eventually lead to cirrhosis. Current treatment of NASH relies on the reduction of body weight and increase in physical activity, but there is no pharmacologic treatment approved as yet. Emerging data indicate that NASH progression results from parallel events originating from the liver as well as from the adipose tissue, the gut and the gastrointestinal tract. Thus, dysfunction of the adipose tissue through enhanced flow of free fatty acids and release of adipocytokines, and alterations in the gut microbiome generate proinflammatory signals that underlie NASH progression. Additional 'extrahepatic hits' include dietary factors and gastrointestinal hormones. Within the liver, hepatocyte apoptosis, ER stress and oxidative stress are key contributors to hepatocellular injury. In addition, lipotoxic mediators and danger signals activate Kupffer cells which initiate and perpetuate the inflammatory response by releasing inflammatory mediators that contribute to inflammatory cell recruitment and development of fibrosis. Inflammatory and fibrogenic mediators include chemokines, the cannabinoid system, the inflammasome and activation of pattern-recognition receptors. Here we review the major mechanisms leading to appearance and progression of NASH, focusing on both extrahepatic signals and local inflammatory mechanisms, in an effort to identify the most promising molecular targets for the treatment of this condition.

Disease-specific heteromerization of G-protein-coupled receptors that target drugs of abuse

Drugs of abuse such as morphine or marijuana exert their effects through the activation of G-protein-coupled receptors (GPCRs), the opioid and cannabinoid receptors, respectively. Moreover, interactions between either of these receptors have been shown to be involved in the rewarding effects of drugs of abuse. Recent advances in the field, using a variety of approaches, have demonstrated that many GPCRs, including opioid, cannabinoid, and dopamine receptors, can form associations between different receptor subtypes or with other GPCRs to form heteromeric complexes. The formation of these complexes, in turn, leads to the modulation of the properties of individual protomers. The development of tools that can selectively disrupt GPCR heteromers as well as monoclonal antibodies that can selectively block signaling by specific heteromer pairs has indicated that heteromers involving opioid, cannabinoid, or dopamine receptors may play a role in various disease states. In this review, we describe evidence for opioid, cannabinoid, and dopamine receptor heteromerization and the potential role of GPCR heteromers in pathophysiological conditions.

Diet induced mild hypercholesterolemia in pigs: local and systemic inflammation, effects on vascular injury - rescue by high-dose statin treatment

Objective

The aim of the present study was to comprehensively evaluate systemic and local inflammation as well as progression of vascular inflammation in normal and mechanically injured vessels in a large animal model of mild hypercholesterolemia. Our aim was also to test the effect of high-dose statin treatment on these processes.

Methods

Pigs were kept for 120 days on a standard diet (SD, n=7), high-cholesterol diet (HCD, n=7) or high-cholesterol diet with Atorvastatin starting after 50 days (STATIN, n=7). Left carotid artery balloon injury was conducted in all groups after 60 days of diet treatment. Biochemical analysis together with evaluation of blood and tissue markers of vascular injury and inflammation were performed in all groups at the end of experiment.

Results

HCD compared to SD induced systemic inflammation demonstrated by increased number of circulating monocytes and lymphocytes. HCD compared to SD induced also local inflammation demonstrated by adipocyte hypertrophy and infiltration of T-lymphocytes in abdominal white adipose tissue, activation of hepatic stellate cells with infiltration of T- and B-lymphocytes and macrophages in the liver and increased macrophage content in lung parenchyma. These changes were accompanied by increased Intima/Media thickness, stenosis, matrix deposition and activated T-cell infiltrates in injured but not in uninjured contralateral carotid artery as we previously reported. The treatment with high-dose statin attenuated all aspects of systemic and local inflammation as well as pathological changes in injured carotid artery.

Conclusions

Diet related mild hypercholesterolemia induce systemic and local inflammation in the liver, lung and adipose tissue that coincide with enhanced inflammation of injured vessel but is without deleterious effect on uninjured vessels. High dose statin attenuated systemic and local inflammation and protected injured vessels. However, finding exact role of reduced systemic and remote inflammation in vascular protection requires further studies.

A starring role for stellate cells in the pancreatic cancer microenvironment

Pancreatic ductal adenocarcinoma is a devastating disease, and patient outcomes have not improved in decades. Treatments that target tumor cells have largely failed. This could be because research has focused on cancer cells and the influence of the stroma on tumor progression has been largely ignored. The focus of pancreatic cancer research began to change with the identification of pancreatic stellate cells, which produce the pancreatic tumor stroma. There is compelling in vitro and in vivo evidence for the influence of pancreatic stellate cells on pancreatic cancer development; several recent preclinical studies have reported encouraging results with approaches designed to target pancreatic stellate cells and the stroma. We review the background and recent advances in these areas, along with important areas of future research that could improve therapy.

Independent and supra-additive effects of alcohol consumption, cigarette smoking, and metabolic syndrome on the elevation of serum liver enzyme levels

We investigated the independent and combined effects of alcohol consumption, cigarette smoking and metabolic syndrome on abnormal liver function, i.e., the elevation of serum liver enzyme levels. Participants of a Korean population-based prospective cohort aged ≥30 years without liver disease, diabetes, or cardiovascular diseases were included. Information on alcohol consumption, smoking status, and metabolic syndrome, defined as per the criteria of the Adult Treatment Panel III, were applied to evaluate their impact on serum levels of aspartate aminotransferase (AST), alanine aminotransferase (ALT), and gamma-glutamyl transferase (GGT). Alcohol consumption, cigarette smoking and metabolic syndrome were the significant individual factors that elevated serum liver enzyme levels. Supra-additive effects of metabolic syndrome and either alcohol consumption or cigarette smoking were also identified. The combination of heavy drinking (≥24 g/day) and metabolic syndrome conferred an effect that was higher than the sum of the two individual effects (Synergic Index (SI): AST, 2.37 [1.20-4.67]; GGT, 1.91 [1.17-3.13]). Only GGT level (odds ratio 6.04 [3.68-9.94], SI 2.33 [1.24-4.41]) was significantly elevated when the effect of moderate drinking (<24 g/day) and metabolic syndrome was combined. The combined effect of any level of alcohol consumption and cigarette smoking was also supra-additive on the elevation of GGT level with SIs of 5.57 for drinking <24 g/day and smoking ≤20 pack years, 5.12 for <24 g/day and >20 pack years, 1.80 for ≥24 g/day and ≤20 pack years, 2.03 for ≥24 g/day and >20 pack years, while only the combined effect of drinking ≥24 g/day and smoking >20 pack years elevated the AST level (SI 4.55 [3.12-6.61]). The combined effect of cigarette smoking and metabolic syndrome was not supra-additive. To prevent fatty liver disease and other related diseases, a multifactorial prevention strategy that includes limited alcohol consumption, smoking cessation and rectification of adverse metabolic profiles is required.

Exposure to ambient particulate matter induces a NASH-like phenotype and impairs hepatic glucose metabolism in an animal model

BACKGROUND & AIMS

Air pollution is a global challenge to public health. Epidemiological studies have linked exposure to ambient particulate matter with aerodynamic diameters<2.5 μm (PM(2.5)) to the development of metabolic diseases. In this study, we investigated the effect of PM(2.5) exposure on liver pathogenesis and the mechanism by which ambient PM(2.5) modulates hepatic pathways and glucose homeostasis.

METHODS

Using "Ohio's Air Pollution Exposure System for the Interrogation of Systemic Effects (OASIS)-1", we performed whole-body exposure of mice to concentrated ambient PM(2.5) for 3 or 10 weeks. Histological analyses, metabolic studies, as well as gene expression and molecular signal transduction analyses were performed to determine the effects and mechanisms by which PM(2.5) exposure promotes liver pathogenesis.

RESULTS

Mice exposed to PM(2.5) for 10 weeks developed a non-alcoholic steatohepatitis (NASH)-like phenotype, characterized by hepatic steatosis, inflammation, and fibrosis. After PM(2.5) exposure, mice displayed impaired hepatic glycogen storage, glucose intolerance, and insulin resistance. Further investigation revealed that exposure to PM(2.5) led to activation of inflammatory response pathways mediated through c-Jun N-terminal kinase (JNK), nuclear factor kappa B (NF-κB), and Toll-like receptor 4 (TLR4), but suppression of the insulin receptor substrate 1 (IRS1)-mediated signaling. Moreover, PM(2.5) exposure repressed expression of the peroxisome proliferator-activated receptor (PPAR)γ and PPARα in the liver.

CONCLUSIONS

Our study suggests that PM(2.5) exposure represents a significant "hit" that triggers a NASH-like phenotype and impairs hepatic glucose metabolism. The information from this work has important implications in our understanding of air pollution-associated metabolic disorders.

Protective effects of hydrogen sulfide on oxidative stress and fibrosis in hepatic stellate cells

In hepatic fibrosis, hepatic stellate cells (HSCs) are activated and change into myofibroblast-like cells which are characterized by increased proliferation and extracellular matrix (ECM) synthesis. In this study, we investigated the regulatory effects of hydrogen sulfide (H2S) on hepatic fibrosis. We detected the proliferation, cell cycle progression, apoptosis, intracellular reactive oxygen species (ROS) and free calcium levels in ferric nitrilotriacetate (Fe-NTA)-activated HSCs treated with sodium hydrogen sulphide (NaHS), an H2S-releasing molecule. We also evaluated the effects of NaHS on fibrosis and ECM synthesis in rats with hepatic fibrosis induced by carbon tetrachloride (CCl4). MTT assay revealed that NaHS (500 µmol/l) suppressed the Fe-NTA-induced proliferation of HSC-T6 cells in a dose-dependent manner. NaHS induced G1 phase cell cycle arrest and apoptosis in the Fe-NTA-treated HSC-T6 cells. Furthermore, in the Fe-NTA-treated HSC-T6 cells, NaHS reduced intracellular levels of ROS at 1, 3 and 6 h and reduced intracellular free calcium levels at 3 and 6 h. H2S administration attenuated hepatic fibrosis and collagen Ⅰ protein expression in the rats with CCl4-induced hepatic fibrosis. In conclusion, exogenous H2S inhibits proliferation and induces cell cycle arrest and apoptosis in activated HSCs and attenuates CCl4-induced hepatic fibrosis and ECM expression.

Role of resistin in the development of insulin resistance and hepatic fibrosis in nonalcoholic fatty liver disease

AIM: To investigate the role of resistin in the development of insulin resistin (IR) and hepatic fibrosis in nonalcoholic fatty liver disease (NAFLD)．

METHODS: Thirty male Wistar rats were randomly divided into control group (n = 15) and model group (n = 15). The control group was fed a normal diet, while the model group was given a high fat diet to induce NAFLD. Five rats in each group were killed at 15, 18 and 21 wk. Serum levels of FBG, FINS, type Ⅲ procollagen (PC Ⅲ), hyaluronic acid (HA), type Ⅳ collagen (C Ⅳ) and laminin (LN) were measured. Insulin resistance was calculated by homeostasis model assessment (HOMA-IR). Liver tissue samples were collected and the degree of hepatic fibrosis was graded by hematoxylin-eosin (HE) staining, VG staining and electron microscopy. RT-PCR was used to determine the expression level of resistin mRNA.

RESULTS: The degree of hepatic fibrosis increased with the time of feeding the high fat diet. Compared to the control group, the levels of HOMA-IR, PC Ⅲ, LN, C Ⅳ, HA and resistin significantly increased, which was particularly prominent at week 21 (33.74 μg/L ± 10.41 μg/L, 2.96 μg/L ± 0.76 μg/L, 4.14 μg/L ± 1.07 μg/L, 19.07 μg/L ± 2.78 μg/L, 848.87 μg/L ± 204.04 μg/L, 0.99 μg/L ± 0.10 μg/L, all P < 0.05 or 0.01). Resistin expression was positively correlated with the levels of HOMA-IR, PCIII, LN, C Ⅳ, and HA (r = 0.77, 0.80, 0.68, 0.67, 0.76, all P < 0.05 or 0.01)．

CONCLUSION: Resistin may induce IR and promote the formation of hepatic fibrosis in NAFLD.

Epidemiology, risk factors, and the promotion of pancreatic cancer: role of the stellate cell

There are approximately 277,000 new cases of pancreatic cancer and 266,000 deaths from pancreatic cancer annually, indicating a mortality rate of 96% of the cases diagnosed. Because of the ineffectiveness of therapies, a major emphasis needs to be placed on prevention. This paper reviews the epidemiology and risk factors for pancreatic cancer, and uses this information to propose plausible research directions for determining the biological mechanisms mediating the effects of risk factors on the promotion of pancreatic cancer, with a focus on the pancreatic stellate cell.

Peroxisome proliferator-activated receptor-γ cross-regulation of signaling events implicated in liver fibrogenesis

Peroxisome proliferator-activated receptor-γ (PPARγ) is a nuclear receptor with transcriptional activity controlling multiple physical and pathological processes. Recently, PPARγ has been implicated in the pathogenesis of liver fibrosis. Its depleted expression has strong associations with the activation and transdifferentiation of hepatic stellate cells, the central event in liver fibrogenesis. Studies over the past decade demonstrate that PPARγ cross-regulates a number of signaling pathways mediated by growth factors and adipokines, and cellular events including apoptosis and senescence. These signaling and cellular events and their molecular interactions with PPARγ system are profoundly involved in liver fibrogenesis. We critically summarize these mechanistic insights into the PPARγ regulation in liver fibrogenesis based on the updated findings in this area. We conclude with a discussion of the impacts of these discoveries on the interpretation of liver fibrogenesis and their potential therapeutic implications. PPARγ activation could be a promising strategy for antifibrotic therapy.

Adiponectin, a key adipokine in obesity related liver diseases

Non-alcoholic fatty liver disease (NAFLD) comprising hepatic steatosis, non-alcoholic steatohepatitis (NASH), and progressive liver fibrosis is considered the most common liver disease in western countries. Fatty liver is more prevalent in overweight than normal-weight people and liver fat positively correlates with hepatic insulin resistance. Hepatic steatosis is regarded as a benign stage of NAFLD but may progress to NASH in a subgroup of patients. Besides liver biopsy no diagnostic tools to identify patients with NASH are available, and no effective treatment has been established. Visceral obesity is a main risk factor for NAFLD and inappropriate storage of triglycerides in adipocytes and higher concentrations of free fatty acids may add to increased hepatic lipid storage, insulin resistance, and progressive liver damage. Most of the adipose tissue-derived proteins are elevated in obesity and may contribute to systemic inflammation and liver damage. Adiponectin is highly abundant in human serum but its levels are reduced in obesity and are even lower in patients with hepatic steatosis or NASH. Adiponectin antagonizes excess lipid storage in the liver and protects from inflammation and fibrosis. This review aims to give a short survey on NAFLD and the hepatoprotective effects of adiponectin.

Liver fibrogenesis and metabolic factors

Mechanisms of liver fibrosis are complex and varied. Among them, metabolic factors are particularly important in the development of fibrosis associated with nonalcoholic steatohepatitis (NASH). These factors are some of the "multiple parallel hits" responsible for liver damage during NASH. Nonalcoholic fatty liver disease (NAFLD) is the hepatic manifestation of the metabolic syndrome. Major profibrogenic protagonists, such as hepatic stellate cells and Kupffer cells, are activated by insulin resistance, apoptosis and local inflammation. Relations between steatosis, insulin resistance and fibrosis are complex. Initially, simple steatosis may be a way to store deleterious free fatty acid in neutral triglycerides. If the lipid storage threshold is exceeded, steatosis may become associated with lipotoxicity. Similarly, interindividual variations of adipose tissue expandability might explain various phenotypes, ranging from "metabolically obese patients with normal weight" to "metabolically normal morbidly obese patients". The metabolic abnormalities in subcutaneous and visceral adipose tissue are insulin resistance and low-grade inflammation, which are associated with increased release of free fatty acid flux and changes in adipocytokines production such as leptin, adiponectin and interleukin 6. The nuclear transcription factor peroxisome proliferator-activated receptor gamma (PPARγ) and the endocannabinoid system might have important roles in liver fibrogenesis and are potential therapeutic targets. Finally, with the development of new molecular tools, gut microbiota has been recently identified for its pleiotropic functions, including metabolism regulation. Better knowledge of these mechanisms should lead to new strategies for the treatment of metabolic factors that play a key role in liver injuries.

Fibrosis in alcoholic and nonalcoholic steatohepatitis

Both alcoholic and nonalcoholic steatohepatitis are relevant causes of cirrhosis and liver-related mortality. Alcohol abuse represents a major health problem in many countries, and liver disease is considered one of the most relevant causes of death related to this factor. Nonalcoholic fatty liver disease is the most common hepatic abnormality in the Western world, and progresses to cirrhosis and hepatocellular carcinoma in a significant portion of cases. Moreover, presence of NAFLD is associated with an increased risk of cardiovascular events. In this review, we discuss the characteristics of fibrosis in alcoholic and nonalcoholic steatohepatitis, focussing on the diagnostic issues and predictive factors. In addition, the pathogenetic mechanisms responsible for appearance and progression of fibrosis in the two conditions are briefly discussed.

Fibroscan: a new noninvasive method for evaluation of liver dysfunction in Turner syndrome

BACKGROUND

Raised liver enzyme value is frequently detected in patients with Turner syndrome (TS), but its clinical importance is still unclear.

OBJECTIVE

To investigate the entity of liver involvement in TS and to avoid the invasiveness of liver biopsy, we planned to measure liver stiffness by transient elastography (TE).

DESIGN

Cross-sectional study.

PATIENTS AND METHODS

Twenty-five consecutive patients with TS and a chronological age ≥ 12·5 years (mean age = 21·7 years), full pubertal development and final height's achievement were enrolled and investigated by blood biochemical analyses [glucose, insulin, aspartate-aminotransferase (AST), alanine-aminotransferase (ALT), gamma-glutamil transferase (GGT), alkaline phosphatase, cholesterol, triglyceride, HDL-cholesterol], ultrasonography and TE of the liver.

RESULTS

Of 25, 7 subjects (28%) showed liver enzyme levels higher than the normal upper limit. Mean liver stiffness value in the entire study group was 4·5 ± 1·7 kPa, being significantly higher in patients with abnormal liver enzymes than in those with normal liver biochemistry (6·0 ± 2·9 vs. 4·0 ± 0·9, P < 0·05). Strong correlations were found between TE values and ALT (P < 0·005), GGT (P < 0·0001), Body mass index (P < 0·05), HOMA index (P < 0·05), HDL-cholesterol (P < 0·05) and triglycerides (P < 0·0001).

CONCLUSIONS

We can assert that (i) liver stiffness, measured by TE, strongly correlates with liver enzyme levels in patients with TS ; (ii) the increased liver stiffness in patients with TS with biochemical signs of liver dysfunction is significantly related to metabolic syndrome parameters; (iii) TE may be an useful tool to select among patients with TS with elevated liver enzymes or other metabolic risk factors, those who deserve more invasive diagnostic procedures, namely liver biopsy, for the best characterisation of liver damage.

Curcumin protects hepatic stellate cells against leptin-induced activation in vitro by accumulating intracellular lipids

Obesity and type II diabetes mellitus are often associated with hyperleptinemia and commonly accompanied by nonalcoholic steatohepatitis, which could cause hepatic fibrosis. During hepatic fibrogenesis, the major effectors hepatic stellate cells (HSCs) become active, coupling with depletion of cellular lipid droplets and downexpression of genes relevant to lipid accumulation. Accumulating evidence supports the proposal that recovering the accumulation of lipids would inhibit HSC activation. We recently reported that leptin stimulated HSC activation, which was eliminated by curcumin, a phytochemical from turmeric. The current study was designed to explore the underlying mechanisms, focusing on their effects on the level of intracellular lipids. We hypothesized that one of the mechanisms by which leptin stimulated HSC activation was to stimulate the depletion of intracellular lipids, which could be abrogated by curcumin by inducing expression of genes relevant to lipid accumulation. In this report, we observed that leptin dose dependently reduced levels of intracellular fatty acids and triglycerides in passaged HSCs, which were eliminated by curcumin. The phytochemical abrogated the impact of leptin on inhibiting the activity of AMP-activated protein kinase (AMPK) in HSCs in vitro. The activation of AMPK resulted in inducing expression of genes relevant to lipid accumulation and increasing intracellular lipids in HSCs in vitro. In summary, curcumin eliminated stimulatory effects of leptin on HSC activation and increased AMPK activity, leading to inducing expression of genes relevant to lipid accumulation and elevating the level of intracellular lipids. These results provide novel insights into mechanisms of curcumin in inhibiting leptin-induced HSC activation.

Advances in understanding the role of leptin, adiponectin and resistin in liver fibrogenesis

Liver fibrosis is a wound healing reaction in response to a variety of chronic liver insults and is characterized by excessive extracellular matrix deposition within the liver. The term "adipocytokines]represents a group of polypeptide molecules produced primarily by adipose tissue. Accumulating evidence demonstrates that adipocytokines play a pivotal role in the pathogenesis of chronic liver diseases, such as nonalcoholic fatty liver disease. In this article, we will summarize the recent findings concerning the role of adipocytokines, such as leptin, adiponectin and resistin, in liver fibrogenesis.

Kupffer cell activation is a causal factor for hepatic insulin resistance

Recruited adipose tissue macrophages contribute to chronic and low-grade inflammation causing insulin resistance in obesity. Similarly, we hypothesized here that Kupffer cells, the hepatic resident macrophages, play a pathogenic role in hepatic insulin resistance induced by a high-fat diet. Mice were fed a normal diet or high-fat diet for 3 days. Kupffer cell activation was evaluated by immunohistochemistry and quantitative RT-PCR. Insulin sensitivity was assessed in vivo by hyperinsulinemic-euglycemic clamp and insulin-activated signaling was investigated by Western blot. Liposome-encapsulated clodronate was injected intravenously to deplete macrophages prior to a short-term exposure to high-fat diet. Here, we characterized a short-term high-fat diet model in mice and demonstrated early hepatic insulin resistance and steatosis concurrent with Kupffer cell activation. We demonstrated that selective Kupffer cell depletion obtained by intravenous clodronate, without affecting adipose tissue macrophages, was sufficient to enhance insulin-dependent insulin signaling and significantly improve hepatic insulin sensitivity in vivo in this short-term high-fat diet model. Our study clearly shows that hepatic macrophage response participates to the onset of high-fat diet-induced hepatic insulin resistance and may therefore represent an attractive target for prevention and treatment of diet- and obesity-induced insulin resistance.

Fatty liver and lipotoxicity

Fatty liver disease comprises a spectrum ranging from simple steatosis to steatohepatitis which can progress to liver cirrhosis and hepatocellular cancer. Hepatic lipotoxicity may ensue when the hepatic capacity to utilize, store and export fatty acids (FA) as triglycerides is overwhelmed. Additional mechanisms of hepatic lipotoxicity include abnormal FA oxidation with formation of reactive oxygen species, disturbances in cellular membrane FA and phospholipid composition, alterations of cholesterol content and ceramide signalling. Lipotoxicity is a key factor for the progression of fatty liver disease by inducing hepatocellular death, activating Kupffer cells and an inflammatory response, impairing hepatic insulin signalling resulting in insulin resistance, and activation of a fibrogenic response in hepatic stellate cells that can ultimately lead to cirrhosis. Therefore, the concept of hepatic lipotoxicity should be considered in future therapeutic concepts for fatty liver disease.