Drugs improving insulin resistance for non-alcoholic fatty liver disease and/or non-alcoholic steatohepatitis

Response to pioglitazone in non-alcoholic fatty liver disease patients with vs. without type 2 diabetes: A meta-analysis of randomized controlled trials

BACKGROUND

Pioglitazone is considered a potential therapy for non-alcoholic fatty liver disease (NAFLD). However, different effects of pioglitazone on NAFLD have been demonstrated in diabetic and non-diabetic patients. Herein, a meta-analysis of randomized, placebo-controlled trials was carried out to indirectly compare pioglitazone in NAFLD patients with vs. without type 2 diabetes.

METHODS

Randomized controlled trials (RCTs) of pioglitazone vs. placebo involving NAFLD patients with or without type 2 diabetes/prediabetes collected from databases were enrolled into this analysis. Methodological quality was employed to evaluate the domains recommended by the Cochrane Collaboration. The analysis covered the changes in histology (fibrosis, hepatocellular ballooning, inflammation, steatosis), liver enzymes, blood lipids, fasting blood glucose (FBS), homeostasis model assessment-IR (HOMA-IR), weight and body mass index (BMI) before and after treatment, and adverse events.

RESULTS

The review covered seven articles, with 614 patients in total, of which three were non-diabetic RCTs. No difference was found in patients with vs. without type 2 diabetes in histology, liver enzymes, blood lipids, HOMA-IR, weight, BMI, and FBS. Moreover, no significant difference was revealed in adverse effects between NAFLD patients with diabetes and without DM, except the incidence of edema that was found to be higher in the pioglitazone group than in the placebo group in NAFLD patients with diabetes.

CONCLUSIONS

Pioglitazone could exert a certain effect on alleviating NAFLD, which was consistent between non-diabetic NAFLD patients and diabetic NAFLD patients in improving histopathology, liver enzymes, and HOMA-IR and reducing blood lipids. Furthermore, there were no adverse effects, except the incidence of edema which is higher in the pioglitazone group in NAFLD patients with diabetes. However, large sample sizes and well-designed RCTs are required to further confirm these conclusions.

Metabolic syndrome, non-alcoholic fatty liver disease and hepatocarcinoma

The term "metabolic syndrome" refers to a group of alterations comprising central obesity reduced high-density lipoprotein cholesterol concentrations, elevated triglyceride concentrations, arterial hypertension, and hyperglycemia. This syndrome has established itself as one of the epidemics of the 21st century. Among its causative agents are insulin resistance, leptin and adiponectin, changes in microbiota, and epigenetics. Its incidence in the European population is estimated to be around 25%. Non-alcoholic fatty liver disease is the hepatic manifestation of metabolic syndrome; its prevalence parallels that of obesity, and it has increased exponentially in recent decades. Recently, several publications have linked metabolic risk factors with the onset and development of hepatocarcinoma, and so it is essential to determine whether patients with non-alcoholic fatty liver disease should follow a protocol for hepatocarcinoma screening. At present, the worldwide incidence of hepatocarcinoma in patients with non-alcoholic fatty liver disease without cirrhosis is only 2.7%. Screening for hepatocarcinoma in patients with non-alcoholic fatty liver disease and cirrhosis is mandatory, but the low incidence of hepatocarcinoma in patients without cirrhosis does not justify the systematic monitoring of this patient population. Current efforts are based on identifying subgroups of patients with non-alcoholic fatty liver disease and a higher-than-average risk of developing hepatocarcinoma.

Antidiabetic Therapy in the Treatment of Nonalcoholic Steatohepatitis

Liver-related diseases are the third-leading causes (9.3%) of mortality in type 2 diabetes (T2D) in Japan. T2D is closely associated with nonalcoholic fatty liver disease (NAFLD), which is the most prevalent chronic liver disease worldwide. Nonalcoholic steatohepatitis (NASH), a severe form of NAFLD, can lead to hepatocellular carcinoma (HCC) and hepatic failure. No pharmacotherapies are established for NASH patients with T2D. Though vitamin E is established as a first-line agent for NASH without T2D, its efficacy for NASH with T2D recently failed to be proven. The effects of pioglitazone on NASH histology with T2D have extensively been established, but several concerns exist, such as body weight gain, fluid retention, cancer incidence, and bone fracture. Glucagon-like peptide 1 (GLP-1) receptor agonists and sodium-glucose cotransporter 2 (SGLT2) inhibitors are expected to ameliorate NASH and NAFLD (LEAN study, LEAD trial, and E-LIFT study). Among a variety of SGLT2 inhibitors, dapagliflozin has already entered the phase 3 trial (DEAN study). A key clinical need is to determine the kinds of antidiabetic drugs that are the most appropriate for the treatment of NASH to prevent the progression of hepatic fibrosis, resulting in HCC or liver-related mortality without increasing the risk of cardiovascular or renal events. Combination therapies, such as glucagon receptor agonist/GLP-1 or gastrointestinal peptide/GLP-1, are under development. This review focused on antidiabetic agents and future perspectives on the view of the treatment of NAFLD with T2D.

Multiple target tissue effects of GLP-1 analogues on non-alcoholic fatty liver disease (NAFLD) and non-alcoholic steatohepatitis (NASH)

Accumulating experimental and clinical evidences over the last decade indicate that GLP-1 analogues have a series of central nervous system and peripheral target tissues actions which are able to significantly influence the liver metabolism. GLP-1 analogues pleiotropic effects proved to be efficacious in T2DM subjects not only reducing liver steatosis and ameliorating NAFLD and NASH, but also in lowering plasma glucose and liver inflammation, improving cardiac function and protecting from kidney dysfunction. While the experimental and clinical data are robust, the precise mechanisms of action potentially involved in these protective multi-target effects need further investigation. Here we present a systematic review of the most recent literature data on the multi-target effects of GLP-1 analogues on the liver, on adipose and muscular tissue and on the nervous system, all capable of influencing significant aspects of the fatty liver disease physiopathology. From this analysis, we can conclude that the multi-target beneficial action of the GLP-1 analogues could explain the positive effects observed in animal and human models on progression of NAFLD to NASH.

Chicory (Cichorium intybus L.) polysaccharides attenuate high-fat diet induced non-alcoholic fatty liver disease via AMPK activation

Chicory polysaccharides (CP) from Cichorium intybus L. roots were extracted and fractionated to isolate two novel polysaccharide fractions, CP-1 and CP-2. CP-1 is a heteropolysaccharide that is mainly composed of sorbin, glucose, fructose, and glucitol at a molar ratio of 1.00:5.58:13.97:10.32. The molecular weight of CP-1 was 8511.4 Da. The hepatoprotective effect of CP-1 was investigated in a rat model of high-fat diet induced non-alcoholic fatty liver disease (NAFLD) rats. Results indicated that the oral administration of CP-1 significantly decreased body weight and liver index in NAFLD rats. CP-1 also significantly increased serum levels of SOD and HDLC, and decreased the levels of ALT, AST, TG, TC, LDL-C, GLU, ALP, LDH, and MDA in NAFLD rats. Meanwhile, CP-1 effectively decreased MDA, TC, and TG, and increased SOD and T-AOC in the livers of NAFLD rats. Furthermore, CP-1 also increased the hepatic expression of p-AMPKα, ATGL, CPT-1, and p-ACC, and reduced the hepatic expression of ACC, FAS, and SCD-1. Moreover, histopathological examination of the livers showed that CP-1 significantly ameliorated the symptoms of NAFLD rats. Therefore, CP-1 significantly attenuated the high-fat diet-induced NAFLD in rats via AMPK activation.

Recent advances in understanding and managing non-alcoholic fatty liver disease

Non-alcoholic fatty liver disease is a leading cause of chronic liver disease that can lead to cirrhosis, hepatocellular cancer, and end-stage liver disease, and it is linked to elevated cardiovascular- and cancer-related morbidity and mortality. Insulin resistance related to metabolic syndrome is the main pathogenic trigger that, in association with adverse genetic, lifestyle, and other factors, precipitates the development of non-alcoholic fatty liver disease. Biochemical markers and radiological imaging, along with liver biopsy in selected cases, help in the disease’s diagnosis and prognostication. Weight loss is the cornerstone treatment of non-alcoholic fatty liver disease; however, it is difficult to achieve and maintain, so pharmacotherapy was developed. The remarkable evolution in understanding disease pathogenesis has led to the development of new medical therapies and even the modification of currently available ones. This review summarizes recent advances in understanding the epidemiology, natural history, pathogenesis, diagnosis, and management of non-alcoholic fatty liver disease.

Current Prevention and Treatment Options for NAFLD

Non-alcoholic fatty liver disease (NAFLD) is now the most common chronic liver disease worldwide and the second leading indication for liver transplantation and the third leading cause of hepatocellular carcinoma (HCC) in the United States. This chapter focuses on the prevention and management of NAFLD. Healthy lifestyle is the cornerstone for the prevention and management of NAFLD and should be recommended to every patient at risk or having established NAFLD. Despite the high prevalence of NAFLD, it should be recognized that the majority of patients will not develop liver-related complications; cardiovascular disease remains the leading cause of death in NAFLD patients. Until further data are available, pharmacological treatment should be restricted to selected patients with confirmed non-alcoholic steatohepatitis. As some agents with primarily anti-fibrotic effect are currently being tested in NAFLD patients, significant fibrosis and cirrhosis may become additional indications for treatment in the future. Because of the surgical morbidity, currently bariatric surgery should only be performed in patients with morbid obesity, although the long-term impact of bariatric surgery on the histology of NAFLD is favorable.

Cardiovascular risk after orthotopic liver transplantation, a review of the literature and preliminary results of a prospective study

Improved surgical techniques and greater efficacy of new anti-rejection drugs have significantly improved the survival of patients undergoing orthotopic liver transplantation (OLT). This has led to an increased incidence of metabolic disorders as well as cardiovascular and cerebrovascular diseases as causes of morbidity and mortality in OLT patients. In the last decade, several studies have examined which predisposing factors lead to increased cardiovascular risk (i.e., age, ethnicity, diabetes, NASH, atrial fibrillation, and some echocardiographic parameters) as well as which factors after OLT (i.e., weight gain, metabolic syndrome, immunosuppressive therapy, and renal failure) are linked to increased cardiovascular mortality. However, currently, there are no available data that evaluate the development of atherosclerotic damage after OLT. The awareness of high cardiovascular risk after OLT has not only lead to the definition of new but generally not accepted screening of high risk patients before transplantation, but also to the need for careful patient follow up and treatment to control metabolic and cardiovascular pathologies after transplant. Prospective studies are needed to better define the predisposing factors for recurrence and de novo occurrence of metabolic alterations responsible for cardiovascular damage after OLT. Moreover, such studies will help to identify the timing of disease progression and damage, which in turn may help to prevent morbidity and mortality for cardiovascular diseases. Our preliminary results show early occurrence of atherosclerotic damage, which is already present a few weeks following OLT, suggesting that specific, patient-tailored therapies should be started immediately post OLT.

A Practical Approach to Gastrointestinal Complications of Diabetes

Gastrointestinal symptoms occur frequently among people with diabetes mellitus and are associated with considerable morbidity. Enteropathy, or large bowel dysfunction, includes constipation, diarrhea and fecal incontinence, and is particularly disturbing for many patients. The pathogenesis of diabetic enteropathy is complex, primarily related to gastrointestinal autonomic dysfunction and etiologically associated with chronic hyperglycemia and diabetes duration. Since there are many other non-iatrogenic and iatrogenic causes of the cardinal symptoms of large bowel dysfunction, patients suspected of having diabetic enteropathy require detailed evaluation. The management of patients with diabetic enteropathy is challenging, and often requires a multidisciplinary approach focusing on a combination of symptom mitigation and glycemic control.

Metabolic syndrome and non-alcoholic fatty liver disease after liver or kidney transplantation

Transplantation is a definitive treatment option for patients with end-stage liver disease, and for some patients with acute liver failure, hepatocellular carcinoma or end-stage renal disease. Long-term post-transplantation complications have become an important medical issue, and cardiovascular diseases (CVD) are now the leading cause of mortality in liver or kidney transplant recipients. The increased prevalence of metabolic syndrome (MS) likely plays a role in the high incidence of post-transplantation CVD. MS and its hepatic manifestation, non-alcoholic fatty liver disease (NAFLD), are prevalent among the general population and in pre- and post-transplantation settings. MS components are associated with recurrent or de novo NAFLD in transplant recipients, potentially influencing post-transplantation survival. Moreover, recent data reveal an important association between NAFLD and risk of incident of chronic kidney disease (CKD). Therefore, NAFLD identification could represent an additional clinical feature for improving the stratification of liver and kidney transplant recipients with regards to risks of CVD, CKD and renal allograft dysfunction. All MS components are potentially modifiable; therefore, it is crucial that hepatologists, nephrologists and primary care physicians become more engaged in managing post-transplantation metabolic complications. The present review discusses the recent clinical evidence regarding the importance of MS and its components after liver and kidney transplantation, as well as the link between MS and NAFLD after liver and kidney transplantation.

Obesity and colorectal liver metastases: Mechanisms and management

INTRODUCTION

Colorectal cancer (CRC) is the third commonest malignancy after lung and breast cancer. The most common cause of mortality from CRC is from distant metastases. Obesity is a known risk factor for primary CRC development. However, its role in metastatic disease progression is not fully understood. The article aims to provide an overview of the role of obesity in colorectal liver metastases (CRLM). Furthermore, possible strategies to minimise this effect are discussed. An electronic search of MedLine, EMBASE, CINAHL and google scholar was performed. Relevant articles were included in the article. Obesity causes localised inflammation within the liver microenvironment which may predispose to metastases development. Furthermore, obesity causes systemic inflammation leading to release of protumourigenic growth factors. Several studies demonstrated the effects of lifestyle modification, medications, bariatric surgery and omega-3 fatty acids on steatosis within the context of liver surgery. It is currently unclear whether obesity directly leads to metastatic disease via chronic systemic inflammation or whether obesity induced steatosis provides a fertile microenvironment for metastases deposition. With a global increase in obesity useful strategies to minimise the effects of obesity on the liver include life-style modification, pre-operative dietary regimes and omega-3 fatty acids intake. Pre-operative optimisation of the patient is a key concept. Further randomised control trials are needed to guide management strategies.

Low simvastatin concentrations reduce oleic acid-induced steatosis in HepG2 cells: An in vitro model of non-alcoholic fatty liver disease

Non-alcoholic fatty liver disease (NAFLD) is an inflammatory condition caused by hepatic lipid accumulation that is associated with insulin resistance, diabetes and metabolic syndrome. Although statins should be used with caution in liver diseases, they are increasingly investigated as a possible treatment for NAFLD. The present study recreated an in vitro model of NAFLD using HepG₂ cells exposed to oleic acid (OA), which was used to quantify OA-induced lipid accumulation in HepG₂ cells treated with various concentrations of simvastatin. In addition, the effect of simvastatin on HepG₂ cell morphology and microparticle generation as a marker of cell apoptosis was assessed. OA-induced lipid accumulation was quantified by Oil Red O staining and extraction for optical density determination. Stained lipid droplets were visualized using phase contrast microscopy. Furthermore, HepG₂ cell-derived microparticles were counted by flow cytometry subsequent to staining for Annexin V. HepG₂ cells treated with 0-1 mM OA showed dose-dependent lipid accumulation. Treatment of HepG₂ cells with increasing concentrations of simvastatin followed by treatment with 1 mM OA showed that low simvastatin concentrations (4-10 µM) were able to reduce lipid accumulation by ~40%, whereas high simvastatin concentrations (20 and 30 µM) induced apoptotic changes in cell morphology and increased the production of Annexin V⁺ microparticles. This suggests that low simvastatin doses may have a role in preventing NAFLD. However, further investigations are required to confirm this action in vivo and to determine the underlying mechanism by which simvastatin reduces hepatic steatosis.

Treatment of Nonalcoholic Fatty Liver Disease: The Role of Medical, Surgical, and Endoscopic Weight Loss

Nonalcoholic fatty liver disease (NAFLD) represents a rapidly growing cause of chronic liver disease in the United States and is associated with significant morbidity and mortality, including progression to liver cirrhosis and hepatocellular carcinoma. NAFLD comprises a spectrum of liver conditions, ranging from simple steatosis to steatosis with inflammation (steatohepatitis) and progressive fibrosis. Weight loss represents a first line therapeutic modality for the management of NAFLD. Herein, we review the evidence base for medical, surgical, and endoscopic approaches to weight loss and their potential impact on the natural history of NAFLD.

Reduced Lysosomal Acid Lipase Activity in Adult Patients With Non-alcoholic Fatty Liver Disease

Non-alcoholic fatty liver disease (NAFLD) is characterized by intra-hepatic fat accumulation and mechanisms involved in its pathogenesis are not fully explained. Lysosomal Acid Lipase (LAL) is a key enzyme in lipid metabolism. We investigated its activity in patients with fatty liver.

LAL activity (nmol/spot/h) was measured in 100 adult healthy subjects (HS) and in 240 NAFLD patients. A sub-analysis on 35 patients with biopsy-proven non-alcoholic steatohepatitis (NASH) was performed.

Median LAL activity was 1.15 (0.95–1.72) in HS. It was significantly reduced in NAFLD [0.78 (0.61–1.01), p < 0.001 vs. HS]. A further reduction was observed in the subgroup of NASH [0.67 (0.51–0.77), p < 0.001 vs. HS]. Patients with LAL activity below median had higher values of serum total cholesterol (p < 0.05) and LDL-c (p < 0.05), and increased serum liver enzymes (ALT, p < 0.001; AST, p < 0.01; GGT, p < 0.01). At multivariable logistic regression analysis, factors associated with LAL activity below median were ALT (OR: 1.018, 95% CI 1.004–1.032, p = 0.011) and metabolic syndrome (OR: 2.551, 95% CI 1.241–5.245, p = 0.011), whilst statin use predicted a better LAL function (OR: 0.464, 95% CI 0.248–0.866, p = 0.016).

Our findings suggest a strong association between impaired LAL activity and NAFLD. A better knowledge of the role of LAL may provide new insights in NAFLD pathogenesis.

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LAL activity is significantly reduced in adult patients with NAFLD, compared to healthy subjects.

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Patients with NASH disclose the lowest value of LAL activity.

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Patients with LAL activity below median have a significant elevation of serum liver enzymes and a worse lipid profile.

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Low LAL activity is associated with metabolic syndrome and lower statin use.

Evidence-based clinical practice guidelines for nonalcoholic fatty liver disease/nonalcoholic steatohepatitis

Nonalcoholic fatty liver disease (NAFLD) is currently the most common cause of chronic liver disease in industrialized countries worldwide, and has become a serious public health issue not only in Western countries but also in many Asian countries including Japan. Within the wide spectrum of NAFLD, nonalcoholic steatohepatitis (NASH) is a progressive form of disease, which often develops into liver cirrhosis and increases the risk of hepatocellular carcinoma. In turn, a large proportion of NAFLD/NASH is the liver manifestation of metabolic syndrome, suggesting that NAFLD/NASH plays a key role in the pathogenesis of systemic atherosclerotic diseases. Currently, a definite diagnosis of NASH requires liver biopsy, though various noninvasive measures are under development. The mainstays of prevention and treatment of NAFLD/NASH include dietary restriction and exercise; however, pharmacological approaches are often necessary. Currently, vitamin E and thiazolidinedione derivatives are the most evidence-based therapeutic options, although the clinical evidence for long-term efficacy and safety is limited. This practice guideline for NAFLD/NASH, established by the Japanese Society of Gastroenterology in cooperation with The Japan Society of Hepatology, covers lines of clinical evidence reported internationally in the period starting from 1983 to January 2012, and each clinical question was evaluated using the GRADE system. Based on the primary release of the full version in Japanese, this English summary provides the core essentials of this clinical practice guideline comprising the definition, diagnosis, and current therapeutic recommendations for NAFLD/NASH in Japan.

Effects of lixisenatide on elevated liver transaminases: systematic review with individual patient data meta-analysis of randomised controlled trials on patients with type 2 diabetes

OBJECTIVE

To evaluate the effects of the glucagon-like peptide-1 receptor agonist lixisenatide on elevated liver blood tests in patients with type 2 diabetes.

DESIGN

Systematic review.

DATA SOURCES

Electronic and manual searches were combined.

STUDY SELECTION

Randomised controlled trials (RCTs) on lixisenatide versus placebo or active comparators for type 2 diabetes were included.

PARTICIPANTS

Individual patient data were retrieved to calculate outcomes for patients with elevated liver blood tests.

MAIN OUTCOME MEASURES

Normalisation of alanine aminotransferase (ALT) and aspartate aminotransferase (AST).

DATA SYNTHESIS

The results of included trials were combined in meta-analyses. Sequential, subgroup and regression analyses were performed to evaluate heterogeneity and bias.

RESULTS

We included 12 RCTs on lixisenatide versus placebo and 3 RCTs with the active comparators liraglutide, exenatide or sitagliptin. The mean treatment duration was 29 weeks. Lixisenatide increased the proportion of patients with normalisation of ALT (risk difference: 0.07; 95% CI 0.01 to 0.14; number needed to treat: 14 patients, p=0.042). The effect was not confirmed in sequential analysis. No effects of lixisenatide were identified on AST, alkaline phosphatase or bilirubin. No evidence of bias was identified. Mixed effect multilevel meta-regression analyses suggest that the benefit of lixisenatide on ALT was limited to patients who were overweight or obese.

CONCLUSIONS

This review suggests that lixisenatide increases the proportion of obese or overweight patients with type 2 diabetes who achieve normalisation of ALT. Additional research is needed to determine if the findings translate to clinical outcome measures.

TRIAL REGISTRATION NUMBER

PROSPERO; CRD42013005779.

Review of nonalcoholic fatty liver disease in women with polycystic ovary syndrome

Polycystic ovary syndrome (PCOS) is the most common endocrine disorder in reproductive-aged women. Women with PCOS frequently have metabolic complications including insulin resistance (IR), early diabetes, hypertension and dyslipidemia. Recent studies have demonstrated an association between PCOS and another metabolic complication: nonalcoholic fatty liver disease (NAFLD). NAFLD occurs as a result of abnormal lipid handling by the liver, which sensitizes the liver to injury and inflammation. It can progress to nonalcoholic steatohepatitis (NASH), which is characterized by hepatocyte injury and apoptosis. With time and further inflammation, NASH can progress to cirrhosis. Thus, given the young age at which NAFLD may occur in PCOS, these women may be at significant risk for progressive hepatic injury over the course of their lives. Many potential links between PCOS and NAFLD have been proposed, most notably IR and hyperandrogenemia. Further studies are needed to clarify the association between PCOS and NAFLD. In the interim, clinicians should be aware of this connection and consider screening for NAFLD in PCOS patients who have other metabolic risk factors. The optimal method of screening is unknown. However, measuring alanine aminotransferase and/or obtaining ultrasound on high-risk patients can be considered. First line treatment consists of lifestyle interventions and weight loss, with possible pharmacologic interventions in some cases.

Management of nonalcoholic fatty liver disease: an evidence-based clinical practice review

AIM

To build a consensus among Chilean specialists on the appropriate management of patients with nonalcoholic fatty liver disease (NAFLD) in clinical practice.

METHODS

NAFLD has now reached epidemic proportions worldwide. The optimal treatment for NAFLD has not been established due to a lack of evidence-based recommendations. An expert panel of members of the Chilean Gastroenterological Society and the Chilean Hepatology Association conducted a structured analysis of the current literature on NAFLD therapy. The quality of the evidence and the level of recommendations supporting each statement were assessed according to the recommendations of the United States Preventive Services Task Force. A modified three-round Delphi technique was used to reach a consensus among the experts.

RESULTS

A group of thirteen experts was established. The survey included 17 open-ended questions that were distributed among the experts, who assessed the articles associated with each question. The levels of agreement achieved by the panel were 93.8% in the first round and 100% in the second and third rounds. The final recommendations support the indication of lifestyle changes, including diet and exercise, for all patients with NAFLD. Proven pharmacological therapies include only vitamin E and pioglitazone, which can be used in nondiabetic patients with biopsy-proven nonalcoholic steatohepatitis (the progressive form of NAFLD), although the long-term safety and efficacy of these therapies have not yet been established.

CONCLUSION

Current NAFLD management is rapidly evolving, and new pathophysiology-based therapies are expected to be introduced in the near future. All NAFLD patients should be evaluated using a three-focused approach that considers the risks of liver disease, diabetes and cardiovascular events.

Metformin protects rat hepatocytes against bile acid-induced apoptosis

BACKGROUND

Metformin is used in the treatment of Diabetes Mellitus type II and improves liver function in patients with non-alcoholic fatty liver disease (NAFLD). Metformin activates AMP-activated protein kinase (AMPK), the cellular energy sensor that is sensitive to changes in the AMP/ATP-ratio. AMPK is an inhibitor of mammalian target of rapamycin (mTOR). Both AMPK and mTOR are able to modulate cell death.

AIM

To evaluate the effects of metformin on hepatocyte cell death.

METHODS

Apoptotic cell death was induced in primary rat hepatocytes using either the bile acid glycochenodeoxycholic acid (GCDCA) or TNFα in combination with actinomycin D (actD). AMPK, mTOR and phosphoinositide-3 kinase (PI3K)/Akt were inhibited using pharmacological inhibitors. Apoptosis and necrosis were quantified by caspase activation, acridine orange staining and Sytox green staining respectively.

RESULTS

Metformin dose-dependently reduces GCDCA-induced apoptosis, even when added 2 hours after GCDCA, without increasing necrotic cell death. Metformin does not protect against TNFα/ActD-induced apoptosis. The protective effect of metformin is dependent on an intact PI3-kinase/Akt pathway, but does not require AMPK/mTOR-signaling. Metformin does not inhibit NF-κB activation.

CONCLUSION

Metformin protects against bile acid-induced apoptosis and could be considered in the treatment of chronic liver diseases accompanied by inflammation.

Cholic acid for hepatic steatosis in patients with lipodystrophy: a randomized, controlled trial

OBJECTIVE

Hepatic steatosis is a common complication in patients with lipodystrophies and can lead to cirrhosis. There is no proven effective therapy for hepatic steatosis, but cholic acid (CA), a farnesoid X receptor agonist, has previously been shown to reduce hepatic triglyceride (TG) content in mice and serum TG in humans. Our objective was to assess clinical efficacy and tolerability of CA therapy in patients with lipodystrophy and hepatic steatosis.

DESIGN

A randomized, double-blind, placebo-controlled, crossover study.

METHODS

Eighteen patients with genetic or autoimmune lipodystrophies and elevated hepatic TG content participated in the study. The intervention was CA (15 mg/kg per day) compared with placebo for a period of 6 months each. Hepatic TG content, the primary outcome variable, was measured with (1)H magnetic resonance spectroscopy at baseline and at 3 and 6 months during each study period. Levels of serum alanine aminotransferase (ALT), aspartate aminotransferase (AST), gamma-glutamyl transpeptidase (GGT), and TG were secondary end points of the study.

RESULTS

Compared with placebo, CA did not reduce (median (interquartile range) hepatic TG content (14.8% (9.4-19.0%) vs 15.9% (10.5-26.5%) respectively; P=0.42) or serum TG ((340 mg/dl (233-433 mg/dl) vs 390 mg/dl (233-595 mg/dl) respectively; P=0.45)). CA therapy also did not change AST, ALT, or GGT levels. Two patients developed diarrhea and excessive flatus while taking CA and these symptoms resolved after reducing the dose of CA.

CONCLUSION

CA was well tolerated but did not reduce hepatic TG content in patients with lipodystrophy.

Nonalcoholic fatty liver disease following liver transplantation

Post-transplant, nonalcoholic hepatic steatosis and steatohepatitis are increasingly recognized as a complication of liver transplantation, and the progression of the latter through fibrosis to cirrhosis has been clearly shown. Non-alcoholic steatohepatitis (NASH) is independently associated with an increased risk of death from cardiovascular and liver diseases. While optimal therapy is not yet available in the post-liver transplant setting, knowledge gained in the therapy of NASH in the non-transplant setting can be used to design therapeutic interventions. In addition, early recognition with protocol liver biopsies and an effective preventive strategy by modifying known risk factors implicated in the recurrence of NASH would be the most effective way to curtail the progression of NASH before an effective treatment can be found. Additional rigorous research aimed at elucidating the pathogenesis, natural history, and selection of immunosuppressants for NASH is clearly warranted.

Oral probiotic microcapsule formulation ameliorates non-alcoholic fatty liver disease in Bio F1B Golden Syrian hamsters

The beneficial effect of a microencapsulated feruloyl esterase producing Lactobacillus fermentum ATCC 11976 formulation for use in non-alcoholic fatty liver disease (NAFLD) was investigated. For which Bio F1B Golden Syrian hamsters were fed a methionine deficient/choline devoid diet to induce non-alcoholic fatty liver disease. Results, for the first time, show significant clinical benefits in experimental animals. Examination of lipids show that concentrations of hepatic free cholesterol, esterified cholesterol, triglycerides and phospholipids were significantly lowered in treated animals. In addition, serum total cholesterol, triglycerides, uric acid and insulin resistance were found to decrease in treated animals. Liver histology evaluations showed reduced fat deposits. Western blot analysis shows significant differences in expression levels of key liver enzymes in treated animals. In conclusion, these findings suggest the excellent potential of using an oral probiotic formulation to ameliorate NAFLD.

Analysis of adipokine concentrations in paediatric non-alcoholic fatty liver disease

BACKGROUND

Non-alcoholic fatty liver disease (NAFLD) is the most common liver disease in children. It is important to distinguish children with more severe disease or steatohepatitis (NASH) from those with the less severe simple steatosis (SS) as prognosis differs. The importance of adipokines in the evolution of NASH is well recognized.

OBJECTIVE

As adipokines are important in mediating inflammation, they may also be useful biomarkers of disease.

METHODS

Plasma from 40 children (30 boys), median age 13.4 years, with liver biopsy-proven NAFLD was analysed. Liver biopsies were scored using the NAFLD activity score and compared with adipokine concentrations.

RESULTS

Median body mass index z-score was 2.12 with a median homeostasis model of assessment- insulin resistance of 4.08. Resistin was lower in NASH than in SS (P = 0.03). Monocyte chemoattractant protein 1 (MCP-1) was also lower in NASH (P = 0.04). MCP-1 was higher in children with severe fibrosis (P = 0.008) with an area under the receiver operating characteristic curve (AUROC) of 0.76. Plasminogen activator inhibitor 1 (PAI-1) was also higher in this group (P = 0.011) with an AUROC of 0.78. There were no significant differences in leptin, adiponectin, adipsin, interleukin (IL) 6, IL10 or tumour necrosis factor α between groups.

CONCLUSION

PAI-1 MCP-1 and resistin were differentially expressed with increasing severity of NAFLD. Though it is unlikely that this profile alone would serve as a biomarker of disease, differences found may contribute to understanding the role of these mediators in NAFLD.

Impact of combined therapy with alpha-lipoic and ursodeoxycolic acid on nonalcoholic fatty liver disease: double-blind, randomized clinical trial of efficacy and safety

BACKGROUND AND PURPOSE

Nonalcoholic fatty liver disease (NAFLD) is one of the causes of a fatty liver, occurring when fat is deposited (steatosis) in the liver not due to excessive alcohol use. It is related to insulin resistance and the metabolic syndrome. The purpose of the present study was to evaluate the impact of combination therapy with alpha-lipoic acid (ALA) and ursodeoxycholic acid (UDCA) on NAFLD.

METHODS

Alpha-lipoic acid 400 mg/day plus UDCA 300 mg/day (ALAUDCA) was investigated in patients over a period of 12 months using a randomized, placebo (PLA)-controlled study with four parallel groups. Serum concentration of gamma-glutamyl transpeptidase (GGT), alanine aminotransferase (ALT), aspartate aminotransferase (AST), albumin and platelets (PLT) were measured at the beginning and at the end of the treatment. Moreover, the AST/ALT ratio and the NAFLD fibrosis score were examined.

RESULTS

A total of 120 patients were randomly assigned to the four groups. ALA and UDCA were safe and well tolerated in the oral daily administration only. AST, ALT, GGT (p < 0.001) showed a significant difference between ALAUDCA and other three groups. Besides, NAFLD fibrosis score underlined a significant reduction (p < 0.04) in the ALAUDCA group, while AST/ALT ratio presented a moderate decline (p > 0.05).

CONCLUSION

ALAUDCA therapy reduced AST, ALT, GGT values and improved NAFLD fibrosis score and AST/ALT ratio, especially in patients who were on a hypocaloric diet. These findings will be useful in patient selection in future clinical trials with ALAUDCA in long-term studies.

Current treatment options for nonalcoholic fatty liver disease and nonalcoholic steatohepatitis

Nonalcoholic fatty liver disease is the leading cause of liver disease in western society. It is a cause of end-stage liver disease, with increased mortality secondary to cirrhosis and its complications. It is also recognized that cardiovascular disease is a significant cause of death in these patients. Significant work evaluating various treatments has been performed in recent years; however, to date, no ideal therapy exists. Lifestyle modification remains the cornerstone of management. The present article reviews the current status of various treatment modalities evaluated in nonalcoholic fatty liver disease.

Medical management of chronic liver diseases in children (part I): focus on curable or potentially curable diseases

The management of children with chronic liver disease (CLD) mandates a multidisciplinary approach. CLDs can be classified into 'potentially' curable, treatable non-curable, and end-stage diseases. Goals pertaining to the management of CLDs can be divided into prevention or minimization of progressive liver damage in curable CLD by treating the primary cause; prevention or control of complications in treatable CLD; and prediction of the outcome in end-stage CLD in order to deliver definitive therapy by surgical procedures, including liver transplantation. Curative, specific therapies aimed at the primary causes of CLDs are, if possible, best considered by a pediatric hepatologist. Medical management of CLDs in children will be reviewed in two parts, with part I (this article) specifically focusing on 'potentially' curable CLDs. Dietary modification is the cornerstone of management for galactosemia, hereditary fructose intolerance, and certain glycogen storage diseases, as well as non-alcoholic steatohepatitis. It is also essential in tyrosinemia, in addition to nitisinone [2-(nitro-4-trifluoromethylbenzoyl)-1,3-cyclohexanedione] therapy, as well as in Wilson disease along with copper-chelating agents such as D-penicillamine, triethylenetetramine dihydrochloride, and ammonium tetrathiomolybdate. Zinc and antioxidants are adjuvant drugs in Wilson disease. New advances in chronic viral hepatitis have been made with the advent of oral antivirals. In children, currently available drugs for the treatment of chronic hepatitis B virus infection are standard interferon (IFN)-α-2, pegylated IFN-α-2 (PG-IFN), and lamivudine. In adults, adefovir and entecavir have also been licensed, whereas telbivudine, emtricitabine, tenofovir disoproxil fumarate, clevudine, and thymosin α-1 are currently undergoing clinical testing. For chronic hepatitis C virus infection, the most accepted treatment is PG-IFN plus ribavirin. Corticosteroids, with or without azathioprine, remain the basic strategy for inducing remission in autoimmune hepatitis. Ciclosporin (cyclosporine) and other immune suppressants may be used for patients who do not achieve remission, or who have significant side effects, with corticosteroid/azathioprine therapy. The above therapies can prevent, or at least minimize, progression of liver damage, particularly if started early, leading to an almost normal quality of life in affected children.

Mechanisms and implications of age-related changes in the liver: nonalcoholic Fatty liver disease in the elderly

Nonalcoholic fatty liver disease (NAFLD) is hepatic steatosis associated with metabolic abnormalities such as overweight/central obesity, insulin resistance, type 2 diabetes (T2D), and dyslipidemia. NAFLD is becoming the most common liver disease in contemporary society, with the highest prevalence in those over 60 years. NAFLD pathology ranges from simple steatosis to a necroinflammatory fibrosing disorder called steatohepatitis (SH), the latter associated with high risk of developing cirrhosis, often occuring in the seventh to ninth decades of life. While the main health implications of NAFLD are increased risk of developing T2D, cardiovascular diseases, and common cancers, there is substantantially increased standardized mortality, and deaths from decompensated cirrhosis and hepatocellular carcinoma (HCC). Little is known about the interactive effects of ageing and NAFLD, with most studies focusing on the younger population. This paper summarises the epidemiology, pathogenesis, and clinical course of NAFLD, with particular attention to persons over age 60 years. An approach to the management of NASH and its complications in the elderly, will also be presented here.

Nonalcoholic fatty liver disease and the coronary artery disease

BACKGROUND

Nonalcoholic fatty liver disease (NAFLD) is increasingly prevalent and is recognized as part of the metabolic syndrome (MetS). Patients with NAFLD have a lower life expectancy compared to the general population, with coronary artery disease (CAD) as the leading cause of death.

AIMS

We aim to address the epidemiological data of CAD, the possible pathogenesis or linkage mechanisms of NAFLD and atherosclerosis and the strategies to reduce the CAD risk in NAFLD patients.

METHODS

We reviewed data from a Medline and PubMed search which was performed to identify relevant literature using search terms "NAFLD," "metabolic syndrome" and "coronary artery disease."

RESULTS

Patients with steatohepatitis, a part of the spectrum of NAFLD, have more cardiovascular events than patients without steatohepatitis. However, the association between liver histological progression and the risk of CAD events is not linear. A multidisciplinary approach to NAFLD patients based on controlling related risk factors and monitoring for CAD risks and liver complications is necessary. The combination of lifestyle modification with pharmacological treatment tailored to each individual's risk factors needs to be considered. There is a need for more research on primary prevention for CAD in NAFLD patients and interventional studies for determining the nature of the relationship between NAFLD and CAD.

CONCLUSIONS

NAFLD is recognized as part of the MetS and increases cardiovascular risks. Therefore, a multidisciplinary approach to these patients of controlling the related risk factors and monitoring for cardiovascular and liver complications must be done.

Pioglitazone, but not metformin, reduces liver fat in Type-2 diabetes mellitus independent of weight changes

BACKGROUND

Pioglitazone (Pio) treatment induces weight gain in Type 2 diabetes mellitus (T2DM), which could worsen hepatic lipid accumulation, and alter adiponectin and high-sensitivity C-reactive protein (hs-CRP).

OBJECTIVE

To compare changes in hepatic lipid, serum adiponectin and hs-CRP in diabetics treated with Pio (with and without weight gain) against metformin (Met) treatment, which produces weight loss.

DESIGN

Fifty-one men and women with T2DM, naive to thiazolidinediones, entered a 16-week, open-label, parallel arm study, where participants were randomized to one of three groups: (1) Pio plus the American Diabetes Association diet (Pio+ADA); (2) Pio plus a portion control weight loss diet (Pio+PC), or (3) metformin plus ADA diet (Met+ADA).

METHODS

Hepatic lipid was assessed with abdominal computed tomography (CT) and the serum adiponectin and hs-CRP by enzyme-linked immunosorbent assay at baseline and study end.

RESULTS

Forty-eight subjects completed the study. The Pio+ADA group gained (mean+/-S.E.M.) 2.15+/-1.09 kg, while Pio+PC and Met+ADA group lost -2.59+/-1.25 and -3.21+/-0.7 kg, respectively. Pio-treated groups (Pio+ADA and Pio+PC) significantly decreased hepatic fat as indicated by increased liver density on CT scan [10.1+/-2.4: 11.4+/-1.0 Hounsfield units (HU)], compared with Met+ADA group (-2.4+/-3.1 HU). The Pio groups demonstrated significantly increased serum adiponectin, (8.6+/-1.5; 7.4+/-1.6 microg/ml) independent of weight change, compared to Met+ADA (-0.14+/-0.6 microgm/ml) group which lost weight. Serum hs-CRP decreased in groups showing weight loss (Pio+PC, -3.1+/-1.7 mg/l; Met+ADA, -1.5+/-1.2 mg/l) compared to Pio+ADA (1.8+/-3.0 mg/l) group that gained weight.

CONCLUSIONS

Pio treatment in T2DM significantly reduced hepatic lipid and increased adiponectin independent of weight change, while decreasing hs-CRP with weight loss.

Optimising the medical management of hyperglycaemia in type 2 diabetes in the Middle East: pivotal role of metformin

AIMS

Increases in the prevalence of type 2 diabetes will likely be greater in the Middle East and other developing countries than in most other regions during the coming two decades, placing a heavy burden on regional healthcare resources.

METHODOLOGY

Medline search, examination of data from major epidemiological studies in the Middle Eastern countries.

RESULTS

The aetiology and pathophysiology of diabetes appears comparable in Middle Eastern and other populations. Lifestyle intervention is key to the management of diabetes in all type 2 diabetes patients, who should be encouraged strongly to diet and exercise. The options for pharmacologic therapy in the management of diabetes have increased recently, particularly the number of potential antidiabetic combinations. Metformin appears to be used less frequently to initiate antidiabetic therapy in the Middle East than in other countries. Available clinical evidence, supported by current guidelines, strongly favours the initiation of antidiabetic therapy with metformin in Middle Eastern type 2 diabetes patients, where no contraindications exist. This is due to its equivalent or greater efficacy relative to other oral antidiabetic treatments, its proven tolerability and safety profiles, its weight neutrality, the lack of clinically significant hypoglycaemia, the demonstration of cardiovascular protection for metformin relative to diet in the UK Prospective Diabetes Study and in observational studies, and its low cost. Additional treatments should be added to metformin and lifestyle intervention as diabetes progresses, until patients are receiving an intensive insulin regimen with or without additional oral agents.

CONCLUSIONS

The current evidence base strongly favours the initiation of antidiabetic therapy with metformin, where no contraindications exist. However, metformin may be under-prescribed in the Middle East.

Insulin sensitizers in nonalcoholic fatty liver disease and steatohepatitis: Current status

Nonalcoholic fatty liver disease (NAFLD), first described in 1980, is now recognized as one of the most common causes of elevated liver enzymes and chronic liver disease in Western countries. The incidence of NAFLD in both adults and children is rising, in conjunction with the burgeoning epidemics of obesity and type 2 diabetes mellitus. NAFLD often coexists with other sequelae of the metabolic syndrome: central obesity, type 2 diabetes, hypertension, and hyperlipidemia. NAFLD encompasses a spectrum of pathologic liver diseases ranging from simple hepatic steatosis to a predominant lobular necro-inflammation, with or without centrilobular fibrosis (called nonalcoholic steatohepatitis or NASH). NASH can progress to cirrhosis, decompensated liver disease, and hepatocellular carcinoma. Though the natural history of NASH is still not clearly defined, it has been observed to progress to cirrhosis in 15%-220% of those affected. Insulin resistance is nearly universal in NASH and is thought to play an important role in its pathogenesis leading to dysregulated lipid metabolism. The prevalence of insulin resistance is reported in the general population to be approaching 45%, suggesting that NAFLD and NASH will contin nue to be an important public health concern. To date, NASH has proven to be a difficult disease to treat. Front-line therapy with lifestyle modifications resulting in weight loss through decreased caloric intake and moderate exercise is generally believed to be beneficial in patients with NASH, but is often difficult to maintain long term. Given that insulin resistance plays a dominant role in the pathogenesis, many studies have examined the use of insulin sensitizers: the biguanides (metformin), thiazolidinediones (pioglitazone, troglitazone, and rosiglitazone), glucagon-like peptide-1-receptor agonists, or incretins (exenatide)in NASH. This review will provide an overview of insulin resistance in NAFLD and provide a detailed summary on the clinical data regarding the use of insulin sensitizers in NASH.

The metabolic syndrome and nonalcoholic fatty liver disease in children

PURPOSE OF REVIEW

Nonalcoholic fatty liver disease (NAFLD) is increasingly prevalent in pediatric-age individuals, in parallel with increasing obesity, and can lead to liver inflammation, fibrosis, and even cirrhosis. NAFLD appears tightly linked with features of the metabolic syndrome (MetS). This review aims to reconsider the clinical presentation, laboratory and pathologic assessment, and treatment of NAFLD, with a focus on its relationship with the MetS.

RECENT FINDINGS

NAFLD occurs with a high prevalence and severity in obese, insulin-resistant adolescents, especially Hispanic males. Pediatric NAFLD may improve with lifestyle therapy and agents that improve insulin sensitivity. In youth, NAFLD appears tightly correlated with components of the MetS, especially visceral fat, which appears to predict fibrosis as well as liver fat. In addition, noninvasive techniques such as transient elastography may help provide data on fibrosis in youth with NAFLD and avoid biopsy.

SUMMARY

The close association between NAFLD and the MetS supports screening for other comorbidities associated with the MetS. Further research is urgently required to best identify effective therapies to prevent and treat NAFLD, but its close association with MetS argues for a focus on strategies designed to improve insulin resistance and components of the MetS.

Is there an effective therapy available for non-alcoholic fatty liver disease?

Non-alcoholic fatty liver disease (NAFLD) is defined as fat accumulation in the liver, ranging from simple steatosis to non-alcoholic steatohepatitis (NASH). Although it used to be considered a benign condition, nowadays it is known to be associated with liver injury and the development of end-stage liver disease. NAFLD is the hepatic manifestation of metabolic syndrome (MS) with an incidence rising in accordance with the increased prevalence of MS, the latter being considered the most common cause of liver enzyme elevation in Western countries. To date, no medications or surgical procedures have been approved for effective treatment of NAFLD, and all of the therapies tested so far must still be regarded as experimental. It is expected that, based on the large amount of data produced in the last few years and the ongoing large multicenter clinical trials, the effective treatment(s) for NASH will soon be defined. Meanwhile, lifestyle interventions and behavior therapy, the only treatments shown to be effective, must be introduced in daily clinical practice and, if possible, supported by public health programs.

The Effect of Metformin and Standard Therapy versus Standard Therapy alone in Nondiabetic Patients with Insulin Resistance and Nonalcoholic Steatohepatitis (NASH): A Pilot Trial

Nonalcoholic steatohepatitis (NASH) is increasing in prevalence and is related to underlying insulin resistance. The aim of this study was to assess the efficacy of metformin on the characteristic histopathologic lesions of NASH. This was a 12-month prospective, randomized, placebo-controlled trial comparing diet and exercise alone to diet, exercise and metformin in nondiabetic patients with insulin resistance and NASH. Patients were randomized to either group A or B. Group A received placebo, dietary counseling, recommendations for weight loss and exercise four times per week. Group B received long-acting metformin 500 mg daily (titrated to 1000 mg daily) plus dietary counseling, recommendations for weight loss and exercise four times per week. Histopathology was assessed at 12 months and biopsies were scored by two pathologists who were blinded to all data. Twenty-three subjects were screened and 19 were randomized to either group A (n ¼10) or group B (n¼ 9). Seven of the 10 subjects in group A completed the study including repeat liver biopsy while all patients in group B completed the study. Body mass index improved in both groups decreasing by 1.7 kg/m(2) in group A and 0.9 kg/m(2) in group B (not significant, control versus treatment). Homeostasis model assessment of insulin resistance scores improved in both groups decreasing by 1.14 in group A and 1.58 in group B (not significant, control versus treatment). No significant difference in histopathology was seen between groups on follow-up liver biopsy. Metformin appeared to have little effect in improvement in liver function tests or liver histology in nondiabetic patients with insulin resistance and NASH. Decrease in BMI through diet and exercise significantly improved HOMA-IR scores, serum aminotransferases and liver histology.

Nonalcoholic fatty liver disease and nonalcoholic steatohepatitis: Selected practical issues in their evaluation and management

Nonalcoholic fatty liver disease (NAFLD) is among the most common causes of chronic liver disease in the western world. It is now recognized that these patients have myriad of important co-morbidities (e.g., diabetes, hypothyroidism and metabolic syndrome). The workup of patients with suspected NAFLD should consist of excluding competing etiologies and systemic evaluation of metabolic comorbidities. NAFLD is histologically categorized into steatosis and steatohepatitis, two states with fairly dichotomous natural history. While significant progress has been made in terms of noninvasively predicting advanced fibrosis, insufficient progress has been made in predicting steatohepatitis. Currently, liver biopsy remains the gold standard for the histological stratification of NAFLD. While sustained weight loss can be effective to treat NASH, it is often difficult to achieve. Foregut bariatric surgery can be quite effective in improving hepatic histology in selected patients without liver failure or significant portal hypertension. Thiazolidinediones have shown promise and the results from the ongoing, large multicenter study should become available soon. Large multicenter studies of CB, receptor anatagonists are also underway but their results will not be available for several years. Several recent studies have highlighted that cardiovascular disease is the single most important cause of morbidity and mortality in this patient population.

CONCLUSION

Health care providers should not only focus on liver disease but also concentrate on aggressively modifying and treating their cardiovascular risk factors.

Current status of therapy in nonalcoholic Fatty liver disease

The obesity epidemic has now spread worldwide. With increase in weight, there is an increase in dysregulated energy metabolism ultimately leading to dysfunction of multiple organ systems recognized as the metabolic syndrome. Nonalcoholic fatty liver disease (NAFLD) is the most common form of chronic liver disease worldwide, and is thought to be the hepatic manifestation of metabolic syndrome. It is a nondiscriminating disease affecting both children and adults and no socioeconomic class is spared. There is a well-defined increase in both liver-related and all-cause mortality. Current projections foresee a continued worsening in prevalence, especially with the increased rate of childhood obesity. Prevention would be the ultimate goal, but with continued trends in obesity, therapeutic options are needed to manage this chronic liver disease and prevent its complications of cirrhosis and even hepatocellular carcinoma. Therapies will need to be affordable, tolerable, and safe to be useful on such a large scale. This article will discuss some of the basic understanding of NAFLD, as well as review the currently tested therapies, some novel therapies, and potential future therapeutic options.

Hepatic dysfunction and insulin insensitivity in type 2 diabetes mellitus: a critical target for insulin-sensitizing agents

The liver plays an essential role in maintaining glucose homeostasis, which includes insulin-mediated processes such as hepatic glucose output (HGO) and uptake, as well as in clearance of insulin itself. In type 2 diabetes, the onset of hyperglycaemia [itself a potent inhibitor of hepatic glucose output (HGO)], alongside hyperinsulinaemia, indicates the presence of hepatic insulin insensitivity. Increased HGO is central to the onset of hyperglycaemia and highlights the need to target hepatic insulin insensitivity as a central component of glucose-lowering therapy. The mechanisms underlying the development of hepatic insulin insensitivity are not well understood, but may be influenced by factors such as fatty acid oversupply and altered adipocytokine release from dysfunctional adipose tissue and increased liver fat content. Furthermore, although the impact of insulin insensitivity as a marker of cardiovascular disease is well known, the specific role of hepatic insulin insensitivity is less clear. The pharmacological tools available to improve insulin sensitivity include the biguanides (metformin) and thiazolidinediones (rosiglitazone and pioglitazone). Data from a number of sources indicate that thiazolidinediones, in particular, can improve multiple aspects of hepatic dysfunction, including reducing HGO, insulin insensitivity and liver fat content, as well as improving other markers of liver function and the levels of mediators with potential involvement in hepatic function, including fatty acids and adipocytokines. The current review addresses this topic from the perspective of the role of the liver in maintaining glucose homeostasis, its key involvement in the pathogenesis of type 2 diabetes and the tools currently available to reduce hepatic insulin insensitivity.

Liver histology changes in nonalcoholic steatohepatitis after one year of treatment with probucol

BACKGROUND

Probucol, a lipid-lowering agent with antioxidant effects, is effective in normalizing liver enzymes in patients with nonalcoholic steatohepatitis (NASH). We studied changes in the liver histology of patients with NASH after use of probucol for one year.

METHODS

Ten patients with biopsy-proven NASH were included. Subjects were given 500 mg probucol daily. Liver biopsies were performed before treatment and after one year.

RESULTS

Eight patients completed treatment. The mean alanine aminotransferase (ALT) and aspartate aminotransferase (AST) levels decreased from 94 and 55 to 41 and 26, respectively (P = 0.004 and 0.001 respectively). The scores for hepatic steatosis and necroinflammation decreased from 7.4 to 5.6 (P = 0.03). The fibrosis score changed from 1.1 to 1.3 (P = 0.79). No adverse drug effects were observed.

CONCLUSION

Probucol is effective in normalizing aminotransferase levels in patients with NASH. It also significantly reduces the histology grade of steatohepatitis after one year of treatment.

Nonalcoholic fatty liver disease: An overview of current insights in pathogenesis, diagnosis and treatment

Estimates of people suffering from overweight (one billion) and obesity (300 million) are increasing. The accumulation of triglycerides in the liver, in the absence of excess alcohol intake, has been described in the early sixties. It was not until 1980, however, that Ludwig et al named this condition nonalcoholic steatohepatitis (NASH). Subsequently, nonalcoholic fatty liver disease (NAFLD) has been used as a general name for conditions ranging from simple steatosis through steatohepatitis to end-stage liver disease (cirrhosis). Many studies have demonstrated the significant correlation with obesity and insulin resistance. Other studies have revealed a significant correlation between hepatic steatosis, cardiovascular disease and increased intima-media thickness. WHO estimated that at least two million patients will develop cirrhosis due to hepatic steatosis in the years to come. Longitudinal cohort studies have demonstrated that those patients with cirrhosis have a similar risk to develop hepatocellular carcinoma as those with other causes of cirrhosis. Taken all together, NAFLD has become the third most important indication for liver transplantation. Therefore, training programmes in internal medicine, gastroenterology and hepatology should stress the importance of diagnosing this entity and treat properly those at risk for developing complications of portal hypertension and concomittant cardiovascular disease. This review will focus on the clinical characteristics, pathophysiology, imaging techniques and the readily available therapeutic options.

High molecular weight adiponectin inhibits proliferation of hepatic stellate cells via activation of adenosine monophosphate-activated protein kinase

Adiponectin is an adipocyte-derived, antidiabetic, antiatherogenic adipocytokine that is present in serum as 3 isoforms. Decreased plasma adiponectin levels are closely associated with the severity of nonalcoholic fatty liver diseases. This study was designed to elucidate a role of adiponectin and its mediator adenosine monophosphate-activated protein kinase (AMPK) on proliferation of activated hepatic stellate cells (HSCs), the key cells promoting fibrosis. Immortalized human HSC line hTERT and primary rat HSCs were stimulated with platelet-derived growth factor (PDGF) with or without pretreatment with AMPK activator 5-aminoimidazole-4-carboxamide-1-4-ribofuranoside (AICAR), metformin, or high molecular weight (HMW) adiponectin. HMW adiponectin dose-dependently suppressed PDGF-induced HSC proliferation. Adenoviral transduction with dominant-negative AMPK (DN-AMPK) abolished the suppressive effect of adiponectin in HSCs. AICAR, metformin, or transduction of constitutively active AMPK attenuated PDGF-induced [(3)H]thymidine incorporation, which was abolished by either a chemical AMPK inhibitor or transduction of DN-AMPK, consistent with an antiproliferative effect of AMPK. The suppressive effect of AMPK on HSC proliferation is mediated through multiple mechanisms, including (1) an inhibition of the AKT pathway, (2) inhibition of NADPH oxidase-dependent reactive oxygen species (ROS) production via induction of antioxidant enzymes, and (3) an increase in the expression of the cyclin-dependent kinase inhibitors p27(kip1) and p21(cip1).

CONCLUSION

Adiponectin inhibits HSC proliferation via activation of AMPK. AMPK activation by AICAR or metformin inhibits HSC proliferation via suppression of ROS production and subsequent inhibition of AKT pathway. Thus, adiponectin and AMPK inhibit HSC proliferation and hepatic fibrosis via multiple molecular mechanisms.

Antioxidant supplements for non-alcoholic fatty liver disease and/or steatohepatitis

BACKGROUND

Non-alcoholic fatty liver disease (NAFLD) is characterised by fatty deposition in the hepatocytes of patients with minimal or no alcohol intake and without other known cause. NAFLD includes a wide spectrum of histologic abnormalities ranging from hepatic steatosis to non-alcoholic steatohepatitis (NASH), or even cirrhosis. Antioxidant supplements, therefore, could potentially protect cellular structures against oxidative stress and the resulting lipid peroxidation.

OBJECTIVES

To systematically evaluate the beneficial and harmful effects of antioxidant supplements versus no intervention, placebo, or other interventions for patients with NAFLD or NASH.

SEARCH STRATEGY

We searched The Cochrane Hepato-Biliary Group Controlled Trials Register (June 2006), the Cochrane Central Register of Controlled Trials (CENTRAL) in The Cochrane Library (Issue 2, 2006), MEDLINE (1966 to June 2006), EMBASE (1980 to June 2006), and the Chinese Biomedical Database (1978 to June 2006). No language restrictions were applied.

SELECTION CRITERIA

Randomised clinical trials evaluating any antioxidant supplements versus no intervention, placebo, or other interventions in patients with NAFLD or NASH. Our inclusion criteria for NAFLD or NASH were based on history of minimal or no alcohol intake, imaging techniques showing hepatic steatosis, and/or histological evidence of hepatic damage (including simple steatosis, fatty infiltration plus nonspecific inflammation, steatohepatitis, fibrosis, and cirrhosis), and by exclusion of other causes of hepatic steatosis.

DATA COLLECTION AND ANALYSIS

We extracted data from the identified trials and contacted authors. We used a random-effects model and fixed-effect model with the significant level set at P = 0.05. We evaluated the methodological quality of the randomised trials by looking at how the generation of allocation sequence, allocation concealment, blinding, and follow-up were performed. We made our analyses following the intention-to-treat method by imputing missing data.

MAIN RESULTS

We identified six trials: two were regarded of high methodological quality and four of low methodological quality. None of the trials reported any deaths. Treatment with antioxidant supplements showed a significant, though not clinically relevant, amelioration of aspartate aminotransferase levels, but not of alanine aminotransferase levels, as compared to placebo or other interventions. Gamma-glutamyl-transpeptidase was decreased, albeit not significantly, in the treatment arm. Radiological and histological data were too limited to draw any definite conclusions on the effectiveness of these agents. Adverse events were non-specific and of no major clinical relevance.

AUTHORS' CONCLUSIONS

There is insufficient data to either support or refute the use of antioxidant supplements for patients with NAFLD. It may be advisable to carry out large prospective randomised clinical trials on this topic.