晚期糖基化终末产物及其受体与非酒精性脂肪性肝病的关系

晚期糖基化终末产物(AGE)是高血糖的标志物,能通过AGE受体(RAGE)发挥致病作用.研究发现,AGE/RAGE与非酒精性脂肪性肝病(NAFLD)的发展关系密切.AGE能增加肝脏的甘油三酯水平,促进单纯性脂肪肝(SFL)的发生,AGE/RAGE可诱导肝脏炎性反应,促进SFL向非酒精性脂肪性肝炎(NASH)发展,并能通过诱导活性氧簇的合成,活化肝脏星状细胞来引起肝纤维化.     

Contribution of the toxic advanced glycation end-products-receptor axis in nonalcoholic steatohepatitis-related hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is one of the most common malignancies worldwide. The main etiologies of HCC are hepatitis B virus and hepatitis C virus (HCV), and non-hepatitis B/non-hepatitis C HCC (NBNC-HCC) has also been identified as an etiological factor. Although the incidence of HCV-related HCC in Japan has decreased slightly in recent years, that of NBNC-HCC has increased. The onset mechanism of NBNC-HCC, which has various etiologies, remains unclear; however, nonalcoholic steatohepatitis (NASH), a severe form of nonalcoholic fatty liver disease, is known to be an important risk factor for NBNC-HCC. Among the different advanced glycation end-products (AGEs) formed by the Maillard reaction, glyceraldehyde-derived AGEs, the predominant components of toxic AGEs (TAGE), have been associated with NASH and NBNC-HCC, including NASH-related HCC. Furthermore, the expression of the receptor for AGEs (RAGE) has been correlated with the malignant progression of HCC. Therefore, TAGE induce oxidative stress by binding with RAGE may, in turn, lead to adverse effects, such as fibrosis and malignant transformation, in hepatic stellate cells and tumor cells during NASH or NASH-related HCC progression. The aim of this review was to examine the contribution of the TAGE-RAGE axis in NASH-related HCC.     

A non-invasive prediction model for non-alcoholic steatohepatitis in paediatric patients with non-alcoholic fatty liver disease

Background

Non-alcoholic fatty liver disease encompasses a spectrum of diseases that range from simple steatosis to the aggressive form of non-alcoholic steatohepatitis. Non-alcoholic steatohepatitis is currently diagnosed through liver biopsy.

Aim

To develop a non-invasive predictive model of non-alcoholic steatohepatitis in children with non-alcoholic fatty liver disease.

Methods

Anthropometric, laboratory, and histologic data were obtained in a cohort of children with biopsy-proven non-alcoholic fatty liver disease. Multivariable logistic regression analysis was employed to create a nomogram predicting the risk of non-alcoholic steatohepatitis. Internal validation was performed by bootstrapping.

Results

Three hundred and two children were included in this analysis with a mean age of 12.3 ± 3.1 years, a mean body mass index percentile of 94.3 ± 6.9, and non-alcoholic steatohepatitis was present in 67%. Following stepwise variable selection, total cholesterol, waist circumference percentile, and total bilirubin were included as variables in the model, with good discrimination with an area under the receiver operating characteristic curve of 0.737.

Conclusions

A nomogram was constructed with reasonable accuracy that can predict the risk of non-alcoholic steatohepatitis in children with non-alcoholic fatty liver disease. If validated externally, this tool could be utilized as a non-invasive method to diagnose non-alcoholic steatohepatitis in children with non-alcoholic fatty liver disease.     

Mechanisms of ductular reaction in non-alcoholic steatohepatitis

Non-alcoholic fatty liver disease (NAFLD) is a disease spectrum caused in part by insulin resistance and genetic predisposition. This disease is primarily characterized by excessive lipid accumulation in hepatocytes in the absence of alcohol abuse and other causes of liver damage. Histologically, NAFLD is divided into several periods: simple steatosis, non-alcoholic steatohepatitis (NASH), hepatic fibrosis, cirrhosis, and hepatocellular carcinoma. With the increasing prevalence of obesity and hyperlipidemia, NAFLD has become the main cause of chronic liver disease worldwide. As a result, the pathogenesis of this disease is drawing increasing attention. Ductular reaction (DR) is a reactive bile duct hyperplasia caused by liver injury that involves hepatocytes, cholangiocytes, and hepatic progenitor cells. Recently, DR is shown to play a pivotal role in simple steatosis progression to NASH or liver fibrosis, providing new research and treatment options. This study reviews several DR signaling pathways, including Notch, Hippo/YAP-TAZ, Wnt/β-catenin, Hedgehog, HGF/c-Met, and TWEAK/Fn14, and their role in the occurrence and development of NASH.     

Hepatocellular carcinoma and non-alcoholic steatohepatitis:The state of play

Hepatocellular carcinoma(HCC) is now the fifth cancer of greatest frequency and the second leading cause of cancer related deaths worldwide. Chief amongst the risks of HCC are hepatitis B and C infection, aflatoxin B1 ingestion, alcoholism and obesity. The latter can promote non-alcoholic fatty liver disease(NAFLD), that can lead to the inflammatory form non-alcoholic steatohepatitis(NASH), and can in turn promote HCC. The mechanisms by which NASH promotes HCC are only beginning to be characterized. Here in this review, we give a summary of the recent findings that describe and associate NAFLD and NASH with the subsequent HCC progression. We will focus our discussion on clinical and genomic associations that describe new risks for NAFLD and NASH promoted HCC. In addition, we will consider novel murine models that clarify some of the mechanisms that drive NASH HCC formation.     

Effects of Metformin on Hepatic Steatosis in Adults with Nonalcoholic Fatty Liver Disease and Diabetes: Insights from the Cellular to Patient Levels

Nonalcoholic fatty liver disease (NAFLD) patients with diabetes constitute a subgroup of patients with a high rate of liver-related complications. Currently, there are no specific drug recommendations for these patients. Metformin, a conventional insulin sensitizer agent, has been widely prescribed in patients with diabetes. Metformin treatment has been shown to be effective at alleviating hepatic lipogenesis in animal models of NAFLD, with a variety of mechanisms being deemed responsible. To date, most studies have enrolled diabetic patients who are treated with metformin, with the drug being taken continuously throughout the study. Although evidence exists regarding the benefits of metformin for NAFLD in preclinical studies, reports on the efficacy of metformin in adult NAFLD patients have had some discrepancies regarding changes in liver biochemistry and hepatic fat content. Evidence has also suggested possible effects of metformin as regards the prevention of hepatocellular carcinoma tumorigenesis. This review was performed to comprehensively summarize the available in vitro, in vivo and clinical studies regarding the effects of metformin on liver steatosis for the treatment of adult NAFLD patients with diabetes. Consistent reports as well as controversial findings are included in this review, and the mechanistic insights are also provided. In addition, this review focuses on the efficacy of metformin as a monotherapy and as a combined therapy with other antidiabetic medications.     

Hepatocellular carcinoma in non-alcoholic steatohepatitis without cirrhosis

Cirrhosis is an emerging major cause of the development of hepatocellular carcinoma (HCC), but in non-alcoholic fatty liver disease (NAFLD), up to 50% of patients with HCC had no clinical or histological evidence of cirrhosis. It is currently challenging to propose general recommendations for screening patients with NAFLD without cirrhosis, and each patient should be evaluated on a case-by-case basis based on the profile of specific risk factors identified. For HCC screening in NAFLD, a valid precision-based screening is needed. Currently, when evaluating this population of patients, the use of non-invasive methods can guide the selection of those who should undergo a screening and surveillance program. Hence, the objective of the present study is to review the epidemiology, the pathophysiology, the histopathological aspects, the current recommendations, and novel perspectives in the surveillance of non-cirrhotic NAFLD-related HCC.     

Gut microbiota contribution to hepatocellular carcinoma manifestation in non-alcoholic steatohepatitis

Recently, the gut microbiota has been recognized as an obvious active player in addition to liver steatosis/steatohepatitis in the pathophysiological mechanisms of the development of hepatocellular carcinoma (HCC), even in the absence of cirrhosis. Evidence from clinical and experimental studies shows the association of specific changes in the gut microbiome and the direct contribution to maintaining liver inflammation and/or cancerogenesis in nonalcoholic fatty liver disease-induced HCC. The composition of the gut microbiota differs significantly in obese and lean individuals, especially in the abundance of pro-inflammatory lipopolysaccharide-producing phyla, and, after establishing steatohepatitis, it undergoes minor changes during the progression of the disease toward advanced fibrosis. Experimental studies proved that the microbiota of obese subjects can induce steatohepatitis in normally fed mice. On the contrary, the transplantation of healthy microbiota to obese mice relieves steatosis. However, further studies are needed to confirm these findings and the mechanisms involved. In this review, we have evaluated well-documented clinical and experimental research on the role of the gut microbiota in the manifestation and promotion of HCC in nonalcoholic steatohepatitis (NASH). Furthermore, a literature review of microbiota alterations and consequences of dysbiosis for the promotion of NASH-induced HCC was performed, and the advantages and limitations of the microbiota as an early marker of the diagnosis of HCC were discussed.     

CEUS and Fibroscan in non-alcoholic fatty liver disease and non-alcoholic steatohepatitis

AIM: To determine intra-hepatic blood flow and liver stiffness in patients with non-alcoholic fatty liver disease(NAFLD) and non-alcoholic steatohepatitis (NASH) using contrast-enhanced ultrasound and fibroscan.METHODS: This prospective study included 15 patients with NAFLD, 17 patients with NASH and 16 healthy controls.In each patient, real-time ultrasound was used to locate the portal vein (PV) and the right liver lobe, and 5 mL of SonoVue? was then injected intravenous in a peripheral vein of the left arm over a 4-s span. Digital recording was performed for 3 min thereafter. The recording was subsequently retrieved to identify an area of interest in the PV area and in the right liver parenchyma(LP) to assess the blood flow by processing the data using dedicated software (Qontrast?, Bracco, Italy).The following parameters were evaluated: percentage of maximal contrast activity (Peak%), time to peak (TTP, s), regional blood volume (RBV, cm3), regional blood flow (RBF, cm3/s) and mean transit time (MTT, s).At 24-48 h post-injection, liver stiffness was evaluated using Fibroscan and measured in kPa. The statistical evaluation was performed using Student’s t test.RESULTS: In the PV, the Peak%, RBV and RBF were significantly reduced in the NAFLD and NASH patientscompared with the controls (Peak%: NAFLD 26.3 ± 6.6,NASH 28.1 ± 7.3 vs controls 55.8 ± 9.9, P 0.001;RBV: NAFLD 4202.3 ± 3519.7, NASH 3929.8 ± 1941.3vs controls 7473 ± 3281, P 0.01; RBF: NAFLD 32.5± 10.8, NASH 32.7 ± 12.1 vs controls 73.1 ± 13.9, P 0.001). The TTP in the PV was longer in both patient groups but reached statistical significance only in the NASH patients compared with the controls (NASH 79.5± 37.8 vs controls 43.2 ± 30, P 0.01). In the LP,the Peak%, RBV and RBF were significantly reduced in the NAFLD and NASH patients compared with the controls (Peak%: NAFLD 43.2 ± 7.3, NASH 41.7 ± 7.7 vs controls 56.6 ± 6.3, P 0.001; RBV: NAFLD 4851.5± 2009, NASH 5069.4 ± 2292.5 vs controls 6922.9 ±2461.5, P 0.05; RBF: NAFLD 55.7 ± 10.1, NASH 54.5 ± 12.1 vs controls 75.9 ± 10.5, P 0.001). The TTP was longer in both patient groups but did not reach statistical significance. The MTT in both the PV and LP in the NAFLD and NASH patients was not different from that in the controls. Liver stiffness was significantly increased relative to the controls only in the NASH patients(NASH: 6.4 ± 2.2 vs controls 4.6 ± 1.5, P 0.05).CONCLUSION: Blood flow derangement within the liver present not only in NASH but also in NAFLD suggests that a vascular flow alteration precedes liver fibrosis development.     

Combination strategies for pharmacologic treatment of non-alcoholic steatohepatitis

Non-alcoholic steatohepatitis (NASH) is defined as hepatic steatosis, inflammation, and hepatocyte injury with or without fibrosis. It has emerged as the second leading indication for liver transplantation with a rising death rate in the non-transplantable population. While there are many drugs in evaluation, currently no approved therapies are on the market for this condition. Given this importance, the Food and Drug Administration has provided formal guidance regarding drug development for stopping or reversing NASH or NASH associated fibrosis. The complex pathogenesis of NASH and its bidirectional relationship with metabolic syndrome has highlighted multiple drugs of interest that address metabolic, inflammatory, and fibrotic factors. A few promising liver specific targets include farnesoid X receptor agonists and peroxisome proliferator-activated receptor agonists. Previously studied drug classes such as glucagon-like peptide-1 analogs or sodium/glucose transport protein 2 inhibitors have also demonstrated ability to improve hepatic steatosis. Here we discuss current rationale, scientific work, and preliminary data in combining multiple drugs for the purposes of a multimodal attack on the pathogenesis of NASH. We highlight multiple Phase 2 and Phase 3 studies that demonstrate the potential to achieve a response rate higher than previously assessed monotherapies for this condition. Ultimately, one of these combination strategies may rise above in its safety and efficacy to become a part of a standardized approach to NASH.     

Insulin sensitizer MSDC-0602K in non-alcoholic steatohepatitis: A randomized,double-blind,placebo-controlled phase IIb study

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Oxidative stress: New insights on the association of non-alcoholic fatty liver disease and atherosclerosis

Non-alcoholic fatty liver disease (NAFLD) represents the most common and emerging chronic liver disease worldwide. It includes a wide spectrum of liver diseases ranging from simple fatty liver to non-alcoholic steatohepatitis (NASH), which may progress to fibrosis and more severe liver complications such as cirrhosis, hepatocellular carcinoma and liver mortality. NAFLD is strongly associated with obesity, insulin resistance, hypertension, and dyslipidaemia, and is now regarded as the liver manifestation of the metabolic syndrome. The increased mortality of patients with NAFLD is primarily a result of cardiovascular disease and, to a lesser extent, to liver related diseases. Increased oxidative stress has been reported in both patients with NAFLD and patient with cardiovascular risk factors. Thus, oxidative stress represents a shared pathophysiological disorder between the two conditions. Several therapeutic strategies targeting oxidative stress reduction in patients with NAFLD have been proposed, with conflicting results. In particular, vitamin E supplementation has been suggested for the treatment of non-diabetic, non-cirrhotic adults with active NASH, although this recommendation is based only on the results of a single randomized controlled trial. Other antioxidant treatments suggested are resveratrol, silybin, L-carnitine and pentoxiphylline. No trial so far, has evaluated the cardiovascular effects of antioxidant treatment in patients with NAFLD. New, large-scale studies including as end-point also the assessment of the atherosclerosis markers are needed.     

Dietary advanced glycation end-products aggravate non-alcoholic fatty liver disease

AIM To determine if manipulation of dietary advanced glycation end product(AGE), intake affects nonalcoholic fatty liver disease(NAFLD) progression and whether these effects are mediated via RAGE. METHODS Male C57Bl6 mice were fed a high fat, high fructose, high cholesterol(HFHC) diet for 33 wk and compared with animals on normal chow. A third group were given a HFHC diet that was high in AGEs. Another group was given a HFHC diet that was marinated in vinegar to prevent the formation of AGEs. In a second experiment, RAGE KO animals were fed a HFHC diet or a high AGE HFHC diet and compared with wildtype controls. Hepatic biochemistry, histology, picrosirius red morphometry and hepatic mR NA were determined. RESULTS Long-term consumption of the HFHC diet generated significant steatohepatitis and fibrosis after 33 wk. In this model, hepatic 4-hydroxynonenal content(a marker of chronic oxidative stress), hepatocyte ballooning, picrosirius red staining, α-smooth muscle actin and collagen type 1A gene expression were all significantly increased. Increasing the AGE content of the HFHC diet by baking further increased these markers of liver damage, but this was abrogated by pre-marination in acetic acid. In response to the HFHC diet, RAGE-/-animals developed NASH of similar severity to RAGE+/+ animals but were protected from the additional harmful effects of the high AGE containing diet. Studies in isolated Kupffer cells showed that AGEs increase cell proliferation and oxidative stress, providing a likely mechanism through which these compounds contribute to liver injury. CONCLUSION In the HFHC model of NAFLD, manipulation of dietary AGEs modulates liver injury, inflammation, and liver fibrosis via a RAGE dependent pathway. This suggests that pharmacological and dietary strategies targeting the AGE/RAGE pathway could slow the progression of NAFLD.     

Immunoglobulin G in non-alcoholic steatohepatitis predicts clinical outcome: A prospective multi-centre cohort study

BACKGROUNDAutoimmune markers including plasma cells (PC), anti-smooth-muscle antibody (ASMA), anti-nuclear antibody (ANA), and raised immunoglobulin G (IgG) are commonly observed in non-alcoholic steatohepatitis (NASH), however their clinical significance is unknown. AIMTo determine if autoimmune markers in NASH patients are independently associated with poorer clinical outcomes.METHODSConsecutive patients with biopsy proven NASH from Christchurch Hospital, New Zealand and Singapore General Hospital (SGH) were included between 2005 to 2016 in a prospective multi-centre cohort study. Patients with other causes of chronic liver disease were excluded. IgG > 14 g/L or globulin fraction > 50%, ANA ≥ 1:40, SMA ≥ 1:40 were considered positive. Multivariate analysis was performed to assess which markers were independently associated with mortality and hepatic decompensation. RESULTSTotal 261 patients were included of which 201 were from SGH. The median age was 53 and 51.9% were male. Advanced fibrosis was present in 31.4% at diagnosis. PC, ASMA, ANA and raised IgG were observed in 13.1%, 4.9%, 27.8% and 30.1% of patients respectively. After multivariate analysis, elevated IgG [Hazard Ratio (HR) 6.79, 95%CI: 2.93-17.15] and fibrosis stage (HR 1.37, 95%CI: 1.03-1.87) were found to be independently associated with increased risk of liver decompensation. Age (HR 1.06, 95%CI: 1.02-1.10) and elevated IgG (HR 3.79, 95%CI: 1.90-7.68) were independent factors associated with higher mortality risk. CONCLUSIONElevated IgG, rather than ANA, ASMA or plasma cells, is independently associated with increased risk of hepatic decompensation and mortality in NASH. It could hence be important for prognostication.     

Insulin sensitizers for the treatment of non-alcoholic fatty liver disease

Non-alcoholic fatty liver disease(NAFLD) is the leading cause of liver disease in the Western world and is closely associated with metabolic syndrome,which includes hypertension,central obesity,dyslipidemia and insulin resistance.NAFLD includes a wide spectrum of liver alterations,ranging from simple hepatic steatosis to variable degrees of fibrosis,cirrhosis and even hepatocellular carcinoma.Although the etiology and progression of the disorder remain poorly understood,insulin resistance is considered to play a pivotal role in the pathogenesis.Insulin sensitizers such as biguanides,thiazolidinediones(TZDs),glucagon-like peptide-1 receptor agonists and dipeptidyl peptidase 4 inhibitors have been studied as therapeutic approaches for NAFLD in recent years.Metformin improves insulin sensitivity and serum alanine transaminase and aspartate transaminase(ALT/AST) levels in the majority of subjects; however,it has no significant effect on liver histology.TZDs improve insulin sensitivity,serum ALT/ AST levels and histology in some cases,but there are some concerns about the safety of long-term therapy.Selection of appropriate patients for avoiding side effects and the treatment of underlying disease are themain points.These drugs are the best choice for the treatment of NAFLD in patients with type 2 DM who are also candidates for treatment with an insulin sensitizer.The present review provides an overview of insulin sensitizers in the treatment of NAFLD.     

Determining the role for uric acid in non-alcoholic steatohepatitis development and the utility of urate metabolites in diagnosis: An opinion review

There has long been a recognised association between non-alcoholic fatty liver disease(NAFLD) and the composite aspects of the metabolic syndrome. Part of this association highlighted the supposed co-existence of elevated uric acid levels in those with NAFLD. There is interest in exploitation of this as a putative diagnostic and prognostic biomarker in NAFLD. Given the increased economic and health burden associated with the NAFLD epidemic, improved methods of population-based, minimally-invasive methods and biomarkers are clearly highly sought and necessary. In this opinion review we review the proposed role of uric acid in the pathogenesis of NAFLD and its potential utilisation in the diagnosis and monitoring of the disease process.     

Th17 involvement in nonalcoholic fatty liver disease progression to non-alcoholic steatohepatitis

The nonalcoholic fatty liver disease(NAFLD) is the hepatic manifestation of the metabolic syndrome. NAFLD encompasses a wide histological spectrum ranging from benign simple steatosis to non-alcoholic steatohepatitis(NASH). Sustained inflammation in the liver is critical in this process. Hepatic macrophages, including liver resident macropaghes(Kupffer cells), monocytes infiltrating the injured liver, as well as specific lymphocytes subsets play a pivotal role in the initiation and perpetuation of the inflammatory response, with a major deleterious impact on the progression of fatty liver to fibrosis. During the last years, Th17 cells have been involved in the development of inflammation not only in liver but also in other organs, such as adipose tissue or lung. Differentiation of a na?ve T cell into a Th17 cell leads to pro-inflammatory cytokine and chemokine production with subsequent myeloid cell recruitment to the inflamed tissue. Th17 response can be mitigated by T regulatory cells that secrete anti-inflammatory cytokines. Both T cell subsets need TGF-β for their differentiation and a characteristic plasticity in their phenotype may render them new therapeutic targets. In this review, we discuss the role of the Th17 pathway in NAFLD progression to NASH and to liver fibrosis analyzing different animal models of liver injury and human studies.     

Focus on emerging drugs for the treatment of patients with non-alcoholic fatty liver disease

Non-alcoholic fatty liver disease(NAFLD)has become the most common liver disorder in Western countries and is increasingly being recognized in developing nations.Fatty liver disease encompasses a spectrum of hepatic pathology,ranging from simple steatosis to non-alcoholic steatohepatitis,cirrhosis,hepatocellular carcinoma and end-stage liver disease.Moreover,NAFLD is often associated with other metabolic conditions,such as diabetes mellitus type 2,dyslipidemia and visceral obesity.The most recent guidelines suggest the management and treatment of patients with NAFLD considering both the liver disease and the associated metabolic co-morbidities.Diet and physical exercise are considered the first line of treatment for patients with NAFLD,but their results on therapeutic efficacy are often contrasting.Behavior therapy is necessary most of the time to achieve a sufficient result.Pharmacological therapy includes a wide variety of classes of molecules with different therapeutic targets and,often,little evidence supporting the real efficacy.Despite the abundance of clinical trials,NAFLD therapy remains a challenge for the scientific community,and there are no licensed therapies for NAFLD.Urgently,new pharmacological approaches are needed.Here,we will focus on the challenges facing actual therapeutic strategies and the most recent investigated molecules.     

Fibroblast growth factor signaling in non-alcoholic fatty liver disease and non-alcoholic steatohepatitis:Paving the way to hepatocellular carcinoma

Metabolic disorders are increasingly leading to non-alcoholic fatty liver disease,subsequent steatohepatitis,cirrhosis and hepatocellular carcinoma.Fibroblast growth factors and their receptors play an important role in maintaining metabolic homeostasis also in the liver and disorders in signaling have been identified to contribute to those pathophysiologic conditions leading to hepatic lipid accumulation and chronic inflammation.While specific and well tolerated inhibitors of fibroblast growth factor receptor activity are currently developed for(non-liver)cancer therapy,treatment of non-alcoholic fatty liver disease and nonalcoholic steatohepatitis is still limited.Fibroblast growth factor-mimicking or restoring approaches have recently evolved as a novel therapeutic option and the impact of such interactions with the fibroblast growth factor receptor signaling network during non-alcoholic fatty liver disease/non-alcoholic steatohepatitis development is reviewed here.