Gut dysbiosis as a driver in alcohol-induced liver injury

Alcohol-related liver disease characterises a broad spectrum of hepatic diseases that result from heavy alcohol use, and include alcohol-related steatosis, steatohepatitis, fibrosis, cirrhosis, and alcoholic hepatitis. Amongst heavy drinkers, progression to more severe forms of alcohol-related liver disease is not universal, with only 20% developing cirrhosis and up to one-third developing alcoholic hepatitis. Non-alcohol-related triggers for severe disease are not well understood, but the intestinal microbiome is thought to be a contributing factor. This review examines the role of the microbiome in mild alcohol-related liver disease, cirrhosis, and alcoholic hepatitis. While most of the literature discusses bacterial dysbiosis, we also discuss the available evidence on fungal (mycobiome) and virome alterations in patients with alcohol-related liver disease. Additionally, we explore the mechanisms by which the microbiome contributes to the pathogenesis of alcohol-related liver disease, including effects on intestinal permeability, bile acid dysregulation, and production of hepatotoxic virulence factors.