The complex function of macrophages and their subpopulations in metabolic injury associated fatty liver disease.

Non-alcoholic fatty liver disease (NAFLD), recently also defined as metabolic dysfunction-associated fatty liver disease (MAFLD), is a major health problem, as it affects ∼25% of the population globally and is a major cause of hepatic cirrhosis and thereby liver failure, as well as hepatocellular carcinoma. MALFD comprises a broad range of pathological conditions in the liver, including simple fat accumulation (steatosis) and the more progressive non-alcoholic steatohepatitis (NASH) that can lead to fibrosis development. Cells of innate immunity, and particularly macrophages, comprising the liver resident Kupffer cells and the recruited monocyte-derived macrophages, play complex roles in NASH-related inflammation and disease progression to fibrosis. Here, we discuss the recent developments with regards to the function of liver macrophage subpopulations during MAFLD development and progression.