Alcoholic liver disease (ALD) is a major cause of chronic liver disease worldwide and can lead to fibrosis and cirrhosis. The latest surveillance report published by the National Institute on Alcohol Abuse and Alcoholism showed that liver cirrhosis was the 12th leading cause of death in the United States, with a total of 29,925 deaths in 2007, 48% of which were alcohol related. The spectrum of ALD includes simple steatosis, alcoholic hepatitis, fibrosis, cirrhosis, and superimposed hepatocellular carcinoma. Early work on the pathogenesis of the disease focused on ethanol metabolism–associated oxidative stress and glutathione depletion, abnormal methionine metabolism, malnutrition, and production of endotoxins that activate Kupffer cells. We review findings from recent studies that have characterized specific intracellular signaling pathways, transcriptional factors, aspects of innate immunity, chemokines, epigenetic features, microRNAs, and stem cells that are associated with ALD, improving our understanding of its pathogenesis. Despite this progress, no targeted therapies are available. The cornerstone of treatment for alcoholic hepatitis remains as it was 40 years ago: abstinence, nutritional support, and corticosteroids. There is an urgent need to develop new pathophysiology-oriented therapies. Recent translational studies of human samples and animal models have identified promising therapeutic targets.
Summary AMPK has emerged as a critical mechanism for salutary effects of polyphenols on lipid metabolic disorders in type 1 and type 2 diabetes. We demonstrate that AMPK interacts with and directly phosphorylates sterol regulatory element binding proteins (SREBP-1c and −2). Ser372 phosphorylation of SREBP-1c by AMPK is sufficient and necessary for inhibition of proteolytic processing and transcriptional activity of SREBP-1c in response to polyphenols and metformin. AMPK stimulates Ser372 phosphorylation, suppresses SREBP-1c cleavage and nuclear translocation, and represses SREBP-1c target gene expression in hepatocytes exposed to high glucose, leading to reduced lipogenesis and lipid accumulation. Hepatic activation of AMPK by the synthetic polyphenol S17834 protects against hepatic steatosis, hyperlipidemia, and accelerated atherosclerosis in diet-induced insulin resistant LDL receptor deficient mice in part through phosphorylation of SREBP-1c Ser372 and suppression of SREBP-1c and −2-dependent lipogenesis. AMPK-dependent phosphorylation of SREBP may offer novel therapeutic strategies to combat insulin resistance, dyslipidemia, and atherosclerosis.
Chronic alcohol consumption is a leading cause of chronic liver disease worldwide, leading to cirrhosis and hepatocellular carcinoma. currently, the most widely used model for alcoholic liver injury is ad libitum feeding with the Lieber-DeCarli liquid diet containing ethanol for 4–6 weeks; however, this model, without the addition of a secondary insult, only induces mild steatosis, slight elevation of serum alanine transaminase (alt) and little or no inflammation. Here we describe a simple mouse model of alcoholic liver injury by chronic ethanol feeding (10-d ad libitum oral feeding with the Lieber-DeCarli ethanol liquid diet) plus a single binge ethanol feeding. this protocol for chronic-plus-single-binge ethanol feeding synergistically induces liver injury, inflammation and fatty liver, which mimics acute-on-chronic alcoholic liver injury in patients. this feeding protocol can also be extended to chronic feeding for longer periods of time up to 8 weeks plus single or multiple binges. chronic-binge ethanol feeding leads to high blood alcohol levels; thus, this simple model will be very useful for the study of alcoholic liver disease (ALD) and of other organs damaged by alcohol consumption.
Liver disease is a major cause of illness and death worldwide. In China alone, liver diseases, primarily viral hepatitis (predominantly hepatitis B virus [HBV]), nonalcoholic fatty liver disease, and alcoholic liver disease, affect approximately 300 million people. The establishment of the Expanded Program on Immunization in 1992 has resulted in a substantial decline in the number of newly HBV‐infected patients; however, the number of patients with alcoholic and nonalcoholic fatty liver diseases is rising at an alarming rate. Liver cancer, one of the most deadly cancers, is the second‐most common cancer in China. Approximately 383,000 people die from liver cancer every year in China, which accounts for 51% of the deaths from liver cancer worldwide. Over the past 10 years, China has made some significant efforts to shed its “leader in liver diseases” title by investing large amounts of money in funding research, vaccines, and drug development for liver diseases and by recruiting many Western‐trained hepatologists and scientists. Over the last two decades, hepatologists and scientists in China have made significant improvements in liver disease prevention, diagnosis, management, and therapy. They have been very active in liver disease research, as shown by the dramatic increase in the number of publications in Hepatology. Nevertheless, many challenges remain that must be tackled collaboratively. In this review, we discuss the epidemiology and characteristics of liver diseases and liver‐related research in China. (Hepatology 2014;60:2098–2107)
Alcoholic liver disease (ALD) is the most prevalent type of chronic liver disease worldwide. ALD can progress from alcoholic fatty liver (AFL) to alcoholic steatohepatitis (ASH), which is characterized by hepatic inflammation. Chronic ASH can eventually lead to fibrosis and cirrhosis and in some cases hepatocellular cancer (HCC). In addition, severe ASH (with or without cirrhosis) can lead to alcoholic hepatitis, which is an acute clinical presentation of ALD that is associated with liver failure and high mortality. Most individuals consuming >40 g of alcohol per day develop AFL; however, only a subset of individuals will develop more advanced disease. Genetic, epigenetic and non-genetic factors might explain the considerable interindividual variation in ALD phenotype. The pathogenesis of ALD includes hepatic steatosis, oxidative stress, acetaldehyde-mediated toxicity and cytokine and chemokine-induced inflammation. Diagnosis of ALD involves assessing patients for alcohol use disorder and signs of advanced liver disease. The degree of AFL and liver fibrosis can be determined by ultrasonography, transient elastography, MRI, measurement of serum biomarkers and liver biopsy histology. Alcohol abstinence achieved by psychosomatic intervention is the best treatment for all stages of ALD. In the case of advanced disease such as cirrhosis or HCC, liver transplantation may be required. Thus, new therapies are urgently needed.
Blood circulating from the intestines to the liver is rich in bacterial products, environmental toxins, and food antigens. To effectively and quickly defend against potentially toxic agents without launching harmful immune responses, the liver relies on its strong innate immune system. This comprises enrichment of innate immune cells (such as macrophages, natural killer, natural killer T, and ␥␦ T cells) and removal of waste molecules and immunologic elimination of microorganisms by liver endothelial cells and Kupffer cells. In addition, the liver also plays an important role in controlling systemic innate immunity through the biosynthesis of numerous soluble pathogen-recognition receptors and complement components. Conclusion: The liver is an organ with predominant innate immunity, playing an important role not only in host defenses against invading microorganisms and tumor transformation but also in liver injury and repair. Recent evidence suggests that innate immunity is also involved in the pathogenesis of liver fibrosis, providing novel therapeutic targets to treat such a liver disorder. (HEPATOLOGY 2008;47:729-736.) T he liver is the largest solid organ in the body with dual inputs for its blood supply. It receives 80% of its blood supply from the gut through the portal vein, which is rich in bacterial products, environment toxins, and food antigens. The remaining 20% is from vascularization by the hepatic artery. Seventy percent of the cell number or 80% of the liver volume is composed of hepatocytes that fulfill the metabolic and detoxifying needs of the body. The remaining cells are made up of nonparenchymal cells, including endothelial cells, stellate cells, Kupffer cells, and lymphocytes. Emerging evidence suggests that the liver is an important part of the body's immune response and is therefore considered an immunologic organ. 1 In this review, evidence is presented demonstrating that the liver plays a key role in innate immune defenses against pathogens, which supports the notion that the liver is an organ with predominant innate immunity and acts as an organ barrier or a filter between the digestive tract and the rest of the body (see details below). Moreover, additional evidence suggests that innate immunity is also involved in the pathogenesis of liver fibrosis, which will also be discussed. Innate ImmunityInnate immunity is an important first line of defense against infection, quickly responding to potential attacks by pathogens. It comprises physical barriers (for example, skin and mucous membranes), chemical barriers (urine, vaginal secretions, and hydrochloric
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