The natural history and risk factors for progression of non-alcoholic fatty liver disease and steatohepatitis

Nonalcoholic fatty liver disease (NAFLD) is a condition of increasing incidence in western Countries seldom associated to other diseases of high prevalence in general population (i.e. diabetes and obesity). NAFLD ranges from simple fatty liver to steatohepatitis (NASH), which may lead to cryptogenic cirrhosis and in some cases hepatocellular carcinoma (HCC). Natural history of NAFLD in humans is poorly understood and progression of liver disease seems to be due to interaction between hosting (i.e. genetic, gut flora, insulin resistance) and environmental factors (social and eating behaviours) that should be responsible of increased oxidative stress within hepatocytes. Even if we need non-invasive markers able to describe the progression of liver disease, only meaning of liver biopsy is useful to characterize the stigmata of worsening such as inflammation and fibrosis.     

Current pharmacological treatment of nonalcoholic fatty liver

Nonalcoholic fatty liver disease (NAFLD) is a frequent and potentially progressive chronic liver disease that occurs in subjects who do not abuse alcohol. NAFLD is often associated with obesity, metabolic syndrome and insulin resistance and its more aggressive form, nonalcoholic steatohepatitis (NASH) is a major cause of cryptogenic cirrhosis. NAFLD/NASH are commonly detected because of elevated serum aminotransferase levels, ultrasonographic fatty liver and, at liver histology, steatosis, inflammation, and occasionally fibrosis that may progress to cirrhosis. No established treatment exists for this potentially serious disorder. Current management of NAFLD/NASH is largely conservative and includes diet regimen, aerobic exercise, and interventions towards the associated metabolic abnormalities. The main concern is therefore to decrease liver steatosis and its progression toward steatohepatitis and fibrosis, and the risk of "cryptogenic" cirrhosis. Among the most promising medications, weight reducing drugs, insulin sensitizers and lipid-lowering agents, antioxidants, bile salts, co-factors increasing the mitochondrial transport of fatty acids are being considered. Among them, thiazolidinediones are the most promising drug family that act by activating PPARgamma nuclear receptors and by regulating both microsomal and peroxisomal lipid oxidative pathways. Pharmacological treatment of obesity and probiotics should be considered as potential therapeutic options. In this review, after summarizing the general background on fatty liver, the most current and attractive pharmacological approaches to the problem of NAFLD/NASH are discussed.     

Current best treatment for non-alcoholic fatty liver disease

Treatment of patients with non-alcoholic fatty liver disease (NAFLD) has typically been focused on the management of associated conditions such as obesity, diabetes mellitus and hyperlipidaemia. NAFLD associated with obesity may be resolved by weight reduction, although the benefits of weight loss have been inconsistent. Improving insulin sensitivity with lifestyle modifications or medications usually improves glucose and lipid levels in patients with diabetes and hyperlipidaemia. Improving insulin sensitivity is expected to improve the liver disease but in many diabetic/hyperlipidaemic patients with NAFLD, the appropriate control of glucose and lipid levels is not always accompanied by improvement of the liver condition. Results of pilot studies evaluating ursodeoxycholic acid, gemfibrozil, betaine, N-acetylcysteine, alphatocopherol, metformin and thiazolidinedione derivatives suggest that these medications may be of potential benefit. This article reviews the treatment modalities currently available for patients with NAFLD, including emerging data from clinical trials evaluating promising medications as well as possibilities for the future.     

Current best treatment for non-alcoholic fatty liver disease

Treatment of patients with non-alcoholic fatty liver disease (NAFLD) has typically been focused on the management of associated conditions such as obesity, diabetes mellitus and hyperlipidaemia. NAFLD associated with obesity may be resolved by weight reduction, although the benefits of weight loss have been inconsistent. Improving insulin sensitivity with lifestyle modifications or medications usually improves glucose and lipid levels in patients with diabetes and hyperlipidaemia. Improving insulin sensitivity is expected to improve the liver disease but in many diabetic/hyperlipidaemic patients with NAFLD, the appropriate control of glucose and lipid levels is not always accompanied by improvement of the liver condition. Results of pilot studies evaluating ursodeoxycholic acid, gemfibrozil, betaine, N-acetylcysteine, αtocopherol, metformin and thiazolidinedione derivatives suggest that these medications may be of potential benefit. This article reviews the treatment modalities currently available for patients with NAFLD, including emerging data from clinical trials evaluating promising medications as well as possibilities for the future.     

肝脏非实质细胞在非酒精性脂肪性肝炎中的作用研究进展

非酒精性脂肪性肝病是全球最流行的肝脏疾病,其疾病谱包含非酒精性脂肪肝、非酒精性脂肪性肝炎、与非酒精性脂肪性肝炎相关的纤维化、肝硬化和肝细胞癌。非酒精性脂肪性肝炎是非酒精性脂肪性肝病进展性的肝脏病理表征,临床上需要药物治疗或其他治疗方式干预,但目前全球尚无针对非酒精性脂肪性肝炎的药物获批上市。非酒精性脂肪性肝炎发病机制复杂,涉及多种细胞内、细胞间的交互作用以及复杂的分子信号通路。非酒精性脂肪性肝炎治疗是一个尚未被满足的巨大临床需求。综述了肝脏中几种主要的非实质细胞在非酒精性脂肪性肝炎发病中的重要作用,同时探讨了非酒精性脂肪性肝炎药物开发靶点与不同细胞之间的相关性。     

Acanthopanax senticosus reverses fatty liver disease and hyperglycemia in ob/ob mice

Non-alcoholic fatty liver disease (NAFLD) is common in obesity. However, weight reduction alone does not prevent the progression of NAFLD to end-stage disease associated with the development of cirrhosis and liver disease. In a previous experiment, 50% ethanol extract of Acanthopanax senticosus stem bark (ASSB) was found to reduce body weight and insulin resistance in high fat diet-induced hyperglycemic and hyperlipidemic ICR mice. To evaluate the anti-steatosis action of ASSB, insulin-resistant ob/ob mice with fatty livers were treated with ASSB ethanol extract for an 8 week-period. ASSB ethanol extract reversed the hepatomegaly, as evident in reduction of % liver weight/body weight ratio. ASSB ethanol extract also specifically lowered circulating glucose and lipids, and enhanced insulin action in the liver. These changes culminated in inhibition of triglyceride synthesis in non-adipose tissues including liver and skeletal muscle. Gene expression studies confirmed reductions in glucose 6-phosphatase and lipogenic enzymes in the liver. These results demonstrate that ASSB ethanol extract is an effective treatment for insulin resistance and hepatic steatosis in ob/ob mice by decreasing hepatic lipid synthesis.     

The treatment of NAFLD

Nonalcoholic fatty liver disease (NAFLD) is becoming an increasing cause of chronic liver damage. The decision of start a medical treatment is based on the documented risk of progression to cirrhosis and liver cancer, when steatohepatitis (NASH) occurs. The therapy of this syndrome requires, as obviously, some considerations on the natural history of the condition, on the efficacy and safety of various therapeutic options, as well as on the costs. Treatment of patients with NAFLD has typically been focused on the management of associated conditions such as obesity, diabetes mellitus and hyperlipemia. Weight loss improves insulin sensitivity, and NASH may resolve with weight reduction. Insulin resistance seems to be the common denominator in many cases of NAFLD. Two classes of drugs have been shown to correct insulin resistance: biguanides (e.g., metformin) and thiazolidinediones (e.g., rosiglitazone and pioglitazone). The last two decades have witnessed a considerable progress in the understanding of the mechanisms respon-sible for the fibrogenic progression of chronic liver diseases. Several drugs believed to be hepatoprotective or antifibrotic agent as UDCA, betaine, vitamin E, lecithin, beta-carotene and selenium have been used in patients with NASH. Silybin is the main component of silymarin that is absorbed when linked whith a phytosome. This substance reduces in rats the lipid-peroxidation and the activaction of hepatic stellate cells. In humans, some non controlled data show that silybin is able to reduce insulin resistance, liver steatosis and plasma markers of liver fibrosis.     

A role for atorvastatin and insulin combination in protecting from liver injury in a model of type 2 diabetes with hyperlipidemia

Non-alcoholic fatty liver disease (NAFLD) is a major complication linked with the metabolic syndrome associated with dyslipidemia, inflammation, and oxidative stress. Impact of type 2 diabetes with hyperlipidemia in NAFLD has to be established, as well as the utility of commonly prescribed anti-diabetic and lipid-lowering agents in improving liver injury markers. Genetic type 2 diabetic Goto–Kakizaki rats were fed with a high-fat diet to test hepatic effects of type 2 diabetes with hyperlipidemia and the effect of atorvastatin and insulin, individually and in combination, in systemic and hepatic inflammatory and oxidative stress markers. High-fat diet aggravated fasting glycemia, systemic and liver lipids, and inflammatory and oxidative stress markers. Individual treatments improved glycemic and lipid profiles, but failed to improve inflammatory markers, whereas insulin was able to reduce liver oxidative stress parameters. Combination of insulin and atorvastatin further improved glycemic and lipid profiles and decreased circulating C-reactive protein levels and liver inflammatory and oxidative stress markers. Insulin and atorvastatin combination leads to better glycaemic and lipid profiles and to better protection against liver inflammation and oxidative stress, giving a superior level of liver protection in type 2 diabetic with hyperlipidemia.     

Review article: current management of non-alcoholic fatty liver disease and non-alcoholic steatohepatitis

Background  Non-alcoholic fatty liver disease (NAFLD) is the hepatic manifestation of metabolic syndrome.
Aim  To assess the epidemiological impact and the current management of patients with NAFLD.
Methods  Published peer-reviewed literature and abstracts concerning NAFLD and non-alcoholic steatohepatitis (NASH) were reviewed. Articles specifically related to epidemiology, diagnosis and current treatment strategies for NAFLD and NASH are summarized.
Results  NAFLD is strongly associated with the epidemic of obesity and type-2 diabetes mellitus, and is estimated to affect about 20–30% of the population in the US. From the spectrum of NAFLD, only patients with biopsy-proven NASH (estimated prevalence in the US population is about 3–5%) have been convincingly shown to progress to cirrhosis, liver failure and hepatocellular carcinoma. The clinical manifestation of NAFLD is usually absent or subtle, with abnormal aminotransferases or incidental radiographic findings of fatty liver. The pathogenesis of NAFLD is attributed to a multi-hit process involving insulin resistance, oxidative stress, apoptotic pathways, and adipocytokines. In 2008, there is no established treatment for NAFLD. Weight loss and treatment for each component of metabolic syndrome. Nevertheless, a large number of agents are being considered in clinical trials of patients with NASH.
Conclusions  Awareness of the tremendous impact of NAFLD as an important cause of chronic liver disease is increasing along with a great deal of information about its pathogenesis. Future, well-designed clinical trials that target specific pathways involved in the pathogenesis of NASH are urgently needed.     

Non-alcoholic steatohepatitis: what can we learn from animal models?

Non-alcoholic fatty liver disease (NAFLD) is one of the most frequent causes of abnormal liver function and correlates with central adiposity, obesity, insulin resistance, the metabolic syndrome and type 2 diabetes mellitus. The pathological spectrum of NAFLD ranges from fatty liver to non-alcoholic steatohepatitis (NASH), advanced fibrosis, cirrhosis, and even hepatocellular carcinoma. Though NAFLD and NASH are becoming a major public health problem, ethical constraints on obtaining human liver tissue limit the interpretability of the data and the ability to delineate cause and effect from complex, interactive disease pathogenic pathways. Animal models of NASH can provide critical information leading to identify potential drug targets and to understand their molecular mechanisms, and are platforms for compound screening in drug development and for the assessment of novel therapeutic strategies. This review is aimed to offer an updated overview of the nutritional, genetic and pharmacologic animal models of NASH. Though the information derived from these models has clear relevance for the comprehension of the molecular basis of human disease, most of them fail to reproduce the full spectrum of liver pathology and the metabolic context that characterizes human NASH. Consequently, it is necessary to establish animal models that can best mimic the actual etiology, progression, and pathogenesis of the disease, and prove effectiveness for examining and selecting compounds with potential therapeutic benefit in NASH.     

Review article: epidemiology, pathogenesis and potential treatments of paediatric non-alcoholic fatty liver disease

Background  Non-alcoholic fatty liver disease (NAFLD) is the most common cause of paediatric liver disease. Similar to NAFLD in adults, NAFLD in children is associated with obesity and insulin resistance and requires liver histology for diagnosis and staging. However, significant histological differences exist between adult and paediatric NAFLD to warrant caution in extrapolation of adult data.
Aim  To review the available data on the epidemiology, pathogenesis, diagnosis and treatment of paediatric NAFLD.
Methods  Relevant articles were identified by Medline searches using the keywords: nonalcoholic fatty liver disease, steatohepatitis, obesity and children.
Results  The rise in childhood obesity has been accompanied by an increase in paediatric NAFLD. Age, gender and race/ethnicity are significant determinants of risk, and sex hormones, insulin sensitivity and adipocytokines are implicated in the pathogenesis of paediatric NAFLD. There is no consensus for treatment of NAFLD; however, data suggest that diet, exercise and some pharmacological therapies may be of benefit.
Conclusions  To evaluate and effectively treat paediatric NAFLD, the pathophysiology and natural history of the disease should be clarified and non-invasive methods for screening, diagnosis, and longitudinal assessment developed. Randomized, controlled, double-blind trials of pharmacological therapies in children with biopsy-proven disease are necessary.     

Systematic review: the epidemiology and natural history of non-alcoholic fatty liver disease and non-alcoholic steatohepatitis in adults

Aliment Pharmacol Ther 2011; 34: 274–285

Summary

Background Non‐alcoholic fatty liver disease (NAFLD) is a common cause of chronic liver disease, and its worldwide prevalence continues to increase with the growing obesity epidemic. This study assesses the epidemiology of NAFLD in adults based on clinical literature published over the past 30 years. Aim To review epidemiology and natural history of non‐alcoholic fatty liver disease and non‐alcoholic steatohepatitis in adults based on clinical literature published over the past 30 years. Methods An in‐depth search of PubMed (1980–2010) was based on five search terms: ‘non‐alcoholic fatty liver disease’ OR ‘non‐alcoholic steatohepatitis’ OR ‘fatty liver’ OR ‘steatosis’ AND ‘incidence’ [MeSH Terms] OR ‘prevalence’ [MeSH Terms] OR ‘natural history’. Studies of paediatric cohorts were excluded. Articles were categorised by topic and summarised, noting generalisations concerning their content. Results Four study categories included NAFLD incidence, prevalence, risk factors and natural history. Studies related to NAFLD prevalence and incidence indicate that the diagnosis is heterogeneous and relies on a variety of assessment tools, including liver biopsy, radiological tests such as ultrasonography, and blood testing such as liver enzymes. The prevalence of NAFLD is highest in populations with pre‐existing metabolic conditions such as obesity and type II diabetes. Many studies investigating the natural history of NAFLD verify the progression from NASH to advanced fibrosis and hepatocellular carcinoma. Conclusions Non‐alcoholic fatty liver disease is the most common cause of elevated liver enzymes. Within the NAFLD spectrum, only NASH progresses to cirrhosis and hepatocellular carcinoma. With the growing epidemic of obesity, the prevalence and impact of NAFLD continues to increase, making NASH potentially the most common cause of advanced liver disease in coming decades.     

Non-alcoholic fatty liver disease in the metabolic syndrome

Non-alcoholic fatty liver disease (NAFLD) is often associated with features of the metabolic syndrome, carrying an increased risk to develop non-alcoholic steatohepatitis (NASH), the inflammatory form of liver steatosis. Epidemiological data confirm that obesity, diabetes, hypertension and hyperlipidemia are frequently found in NAFLD and worsen its prognosis because of increased risk of fibrotic evolution, eventually leading to liver cirrhosis. Recent studies confirm the close relationship between the metabolic syndrome and liver steatosis, and further support the detrimental role of oxidative stress and lipid peroxidation, which are pathophysiological processes present in both conditions. Novel diagnostic tools and life style modifications together with targeted therapeutic actions are urgently needed for the management of liver dysfunction in course of metabolic syndrome.     

Novel role of NPC1L1 in the regulation of hepatic metabolism: potential contribution of ezetimibe in NAFLD/NASH treatment

Non-alcoholic fatty liver disease (NAFLD) is the most common chronic liver disease in Western countries and also in other parts of the world. NAFLD encompasses a histological spectrum ranging from simple steatosis to steatohepatitis, advanced fibrosis and inflammatory changes. It frequently occurs with features of the metabolic syndrome including obesity, type 2 diabetes mellitus, dyslipidemia and hypertension. In fact, the metabolic syndrome is a strong predictor of NAFLD. Recently, Niemann-Pick C1-like 1 (NPC1L1) has been shown to play a pivotal role in cholesterol absorption. Unlike mouse NPC1L1 protein, predominantly expressed in the intestines, human and rat NPC1L1 is also abundantly expressed in the liver. Though the exact functions of hepatic NPC1L1 remain unknown, NPC1L1 may facilitate the hepatic accumulation of cholesterol. This raises a potential possibility that ezetimibe may improve fatty liver formation. In this review, potential role of lipid metabolism in NAFLD and its possible modulation through NPC1L1 blockade is discussed.     

Recent advances in the treatment of non-alcoholic fatty liver disease

Non-alcoholic steatohepatitis is a liver disease strongly associated with features of the metabolic syndrome. It is part of the disease spectrum of non-alcoholic fatty liver disease, which is now thought to be the most common cause of chronic liver disease in the US and other Western countries. Initially this condition was considered innocuous but it is now recognised as having the potential to progress to cirrhosis and its complications. The role of insulin resistance and oxidative stress in its pathogenesis is increasingly accepted. Current investigations are directed towards a better understanding of the natural history, pathogenesis and development of treatment strategies. Several therapeutic modalities, including antioxidants, insulin-sensitising agents and lipid-lowering agents, have been evaluated for the treatment of these patients, mostly in small clinical trials. Despite promising results, no therapy has demonstrated a proven benefit.     

Nonalcoholic fatty liver disease: pathogenesis and potential for nuclear receptors as therapeutic targets

Nonalcoholic fatty liver disease (NAFLD) is a consequence of insulin resistance encompassing a spectrum that extends from simple hepatic steatosis through to nonalcoholic steatohepatitis (NASH), a condition that may progress to cirrhosis with its associated complications. A subset of nuclear receptors act as intracellular sensors for cholesterol metabolites, free fatty acids, and a range of other lipophilic molecules with pivotal roles in energy homeostasis and inflammation. These receptors represent attractive drug targets for the management of NAFLD and NASH as well as related conditions such as type 2 diabetes and the broader metabolic syndrome. To date, human studies have concentrated on peroxisome proliferator-activated receptor (PPAR) agonists, particularly those directed at PPARgamma. However, these drugs have significant limitations, so alternate approaches to nuclear receptor targeting are being explored.     

GI epidemiology: nonalcoholic fatty liver disease

BACKGROUND: Nonalcoholic fatty liver disease (NAFLD) is a common diagnosis in clinical practice. Insulin resistance and oxidative stress play an important role in NAFLD development and progression. AIM: To review the data available on the epidemiology and natural history of NAFLD as well as the risk factors for its development and the areas where future research is necessary. RESULTS /CONCLUSIONS: NAFLD may affect individuals of any age range and race/ethnicity. NAFLD affects one in three adults and one in ten children/adolescents in the United States. Mortality in patients with NAFLD is significantly higher than in the general population of same age and gender with liver-related complications being a common cause of death. Liver-related morbidity and mortality in NAFLD occurs when the disease has progressed to advanced fibrosis and cirrhosis. Further studies are necessary to determine the impact of NAFLD on health-related quality of life and resources utilization, and to the extent to which preventing the development of the metabolic syndrome would prevent NAFLD development and reduce liver-related morbidity and mortality. Lifestyle intervention may improve NAFLD, but medications that increase insulin sensitivity and the antioxidant defenses in the liver deserve evaluation in carefully controlled trials.     

PPAR激动剂在治疗非酒精性脂肪性肝病中的应用前景

由于肥胖症和2型糖尿病患者越来越多,非酒精性脂肪性肝病(NAFLD)也呈现逐年上升趋势。NAFLD可引起肝硬化和肝癌等并发症,严重威胁公众健康,目前尚无有效治疗NAFLD及其并发症的药物。肝脏甘油三酯聚集是NAFLD的重要标志,过氧化物酶体增殖物活化受体(PPAR)可参与脂代谢、糖代谢以及炎症的调控。本文综述了PPAR参与NAFLD的可能作用机制以及治疗NAFLD的PPAR激动剂的研究进展。