Alcoholic liver disease (ALD) is one of the leading causes of liver diseases and liver-related death worldwide. Of the many factors that contribute to the pathogenesis of ALD, gut-derived ...lipopolysaccharide (LPS) plays a central role in induction of steatosis, inflammation, and fi brosis in the liver. In this review, we discuss the mechanisms by which alcohol contributes to increased gut permeability, the activation of Kupffer cells, and the infl ammatory cascade by LPS. The role of the Toll-like receptor 4...
The increasing epidemic of obesity worldwide is linked to serious health effects, including increased prevalence of type 2 diabetes mellitus, cardiovascular disease and nonalcoholic fatty liver ...disease (NAFLD). NAFLD is the liver manifestation of the metabolic syndrome and includes the spectrum of liver steatosis (known as nonalcoholic fatty liver) and steatohepatitis (known as nonalcoholic steatohepatitis), which can evolve into progressive liver fibrosis and eventually cause cirrhosis. Although NAFLD is becoming the number one cause of chronic liver diseases, it is part of a systemic disease that affects many other parts of the body, including adipose tissue, pancreatic β-cells and the cardiovascular system. The pathomechanism of NAFLD is multifactorial across a spectrum of metabolic derangements and changes in the host microbiome that trigger low-grade inflammation in the liver and other organs. Peroxisome proliferator-activated receptors (PPARs) are a group of nuclear regulatory factors that provide fine tuning for key elements of glucose and fat metabolism and regulate inflammatory cell activation and fibrotic processes. This Review summarizes and discusses the current literature on NAFLD as the liver manifestation of the systemic metabolic syndrome and focuses on the role of PPARs in the pathomechanisms as well as in the potential targeting of disease.
Both alcoholic liver disease (ALD) and nonalcoholic fatty liver disease are characterized by massive lipid accumulation in the liver accompanied by inflammation, fibrosis, cirrhosis, and ...hepatocellular carcinoma in a substantial subgroup of patients. At several stages in these diseases, mediators of the immune system, such as cytokines or inflammasomes, are crucially involved. In ALD, chronic ethanol exposure sensitizes Kupffer cells to activation by lipopolysaccharides through Toll‐like receptors, e.g., Toll‐like receptor 4. This sensitization enhances the production of various proinflammatory cytokines such as interleukin‐1 (IL‐1) and tumor necrosis factor‐alpha, thereby contributing to hepatocyte dysfunction, necrosis, and apoptosis and the generation of extracellular matrix proteins leading to fibrosis/cirrhosis. Indeed, neutralization of IL‐1 by IL‐1 receptor antagonist has recently been shown to potently prevent liver injury in murine models of ALD. As IL‐1 is clearly linked to key clinical symptoms of acute alcoholic hepatitis such as fever, neutrophilia, and wasting, interfering with the IL‐1 pathway might be an attractive treatment strategy in the future. An important role for IL‐1‐type cytokines and certain inflammasomes has also been demonstrated in murine models of nonalcoholic fatty liver disease. IL‐1‐type cytokines can regulate hepatic steatosis; the NLR family pyrin domain containing 3 inflammasome is critically involved in metabolic dysregulation. Conclusion: IL‐1 cytokine family members and various inflammasomes mediate different aspects of both ALD and nonalcoholic fatty liver disease. (Hepatology 2016;64:955‐965)
Patients with acutely decompensated cirrhosis have a dismal prognosis and frequently progress to acute-on-chronic liver failure, which is characterised by hepatic and extrahepatic organ failure(s). ...The pathomechanisms involved in decompensation and disease progression are still not well understood, and as specific disease-modifying treatments do not exist, research to identify novel therapeutic targets is of the utmost importance. This review amalgamates the latest knowledge on disease mechanisms that lead to tissue injury and extrahepatic organ failure – such as systemic inflammation, mitochondrial dysfunction, oxidative stress and metabolic changes – and marries these with the classical paradigms of acute decompensation to form a single paradigm. With this detailed breakdown of pathomechanisms, we identify areas for future research. Novel disease-modifying strategies that break the vicious cycle are urgently required to improve patient outcomes.
Background: Multiple line of clinical and experimental evidence demonstrates that both acute, moderate, and chronic, excessive alcohol use result in various abnormalities in the functions of the ...immune system.
Methods: Medline and Pubmed databases were used to identify published reports with particular interest in the period of 2000–2008 in the subject of alcohol use, infection, inflammation, innate, and adaptive immunity.
Results: This review article summarizes recent findings relevant to acute or chronic alcohol use‐induced immunomodulation and its consequences on host defense against microbial pathogens and tissue injury. Studies with in vivo and in vitro alcohol administration are both discussed. The effects of alcohol on lung infections, trauma and burn injury, liver, pancreas, and cardiovascular diseases are evaluated with respect to the role of immune cells. Specific changes in innate immune response and abnormalities in adaptive immunity caused by alcohol intake are detailed.
Conclusion: Altered inflammatory cell and adaptive immune responses after alcohol consumption result in increased incidence and poor outcome of infections and other organ‐specific immune‐mediated effects.
Hepatocyte damage and inflammation in monocytes/macrophages are central to the pathogenesis of alcoholic hepatitis (AH). MicroRNAs (miRNAs) regulate all of these processes. MiRNA-122 is abundantly ...expressed in hepatocytes while monocytes/macrophages have low levels. The role of exosomes in AH and possible cross talk between hepatocyte-derived exosomes and immune cells is not explored yet. Here, we show that the number of exosomes significantly increases in the sera of healthy individuals after alcohol binge drinking and in mice after binge or chronic alcohol consumption. Exosomes isolated from sera after alcohol consumption or from in vitro ethanol-treated hepatocytes contained miRNA-122. Exosomes derived from ethanol-treated Huh7.5 cells were taken up by the recipients THP1 monocytes and horizontally transferred a mature form of liver-specific miRNA-122. In vivo, liver mononuclear cells and Kupffer cells from alcohol-fed mice had increased miRNA-122 levels. In monocytes, miRNA-122 transferred via exosomes inhibited the HO-1 pathway and sensitized to LPS stimulation and increased levels of pro-inflammatory cytokines. Finally, inflammatory effects of exosomes from ethanol-treated hepatocytes were prevented by using RNA interference via exosome-mediated delivery of a miRNA-122 inhibitor. These results demonstrate that first, exosomes mediate communication between hepatocytes and monocytes/macrophages and second, hepatocyte-derived miRNA-122 can reprogram monocytes inducing sensitization to LPS.
Binge drinking, the most common form of alcohol consumption, is associated with increased mortality and morbidity; yet, its biological consequences are poorly defined. Previous studies demonstrated ...that chronic alcohol use results in increased gut permeability and increased serum endotoxin levels that contribute to many of the biological effects of chronic alcohol, including alcoholic liver disease. In this study, we evaluated the effects of acute binge drinking in healthy adults on serum endotoxin levels. We found that acute alcohol binge resulted in a rapid increase in serum endotoxin and 16S rDNA, a marker of bacterial translocation from the gut. Compared to men, women had higher blood alcohol and circulating endotoxin levels. In addition, alcohol binge caused a prolonged increase in acute phase protein levels in the systemic circulation. The biological significance of the in vivo endotoxin elevation was underscored by increased levels of inflammatory cytokines, TNFα and IL-6, and chemokine, MCP-1, measured in total blood after in vitro lipopolysaccharide stimulation. Our findings indicate that even a single alcohol binge results in increased serum endotoxin levels likely due to translocation of gut bacterial products and disturbs innate immune responses that can contribute to the deleterious effects of binge drinking.
PDF
