New insights in the pathogenesis of alcohol-related liver disease:The metabolic,immunologic,and neurologic pathways

Alcohol-related liver disease(ALD)became an important health issue worldwide.Following chronic alcohol consumption,the development of ALD might be caused by metabolic and immunologic factors,such as reactive oxygen species(ROS)and pro-inflammatory cytokines.For example,hepatic cytochrome P4502E1 enzyme increases ROS production and stimulates de novo lipogenesis after alcohol exposure.In addition,damage-and pathogen-associated molecular patterns stimulate their specific receptors in nonparenchymal cells,including Kupffer cells,hepatic stellate cells(HSCs),and lymphocytes,which result in hepatocyte death and infiltration of pro-inflammatory cells(e.g.,neutrophils and macrophages)in the liver.Moreover,our studies have suggested the novel involvement of neurologic signaling pathways(e.g.,endocannabinoid and glutamate)through the metabolic synapse between hepatocytes and HSCs in the development of alcohol-related hepatic steatosis.Additionally,agouti-related protein and beta2-adrenergic receptors aggravate hepatic steatosis.Furthermore,organ-crosstalk has emerged as a critical issue in ALD.Chronic alcohol consumption induces dysbiosis and barrier disruption in the gut,leading to endotoxin leakage into the portal circulation,or lipolysis-mediated transport of triglycerides from the adipose tissue to the liver.In summary,this review addresses multiple pathogeneses of ALD,provides novel neurologic signaling pathways,and emphasizes the importance of organ-crosstalk in the development of ALD.