Liver immunology: Biological role and clinical significance.

Liver diseases are of growing interest to clinicians and researchers due to their high prevalence, difficulty in early diagnosis, and limited treatment options. The liver is an important organ at the intersection of many metabolic and immune pathways. To this end, it contains a large number of immune cells of both the innate and adaptive immune system that perform multiple functions, detecting and destroying pathogens that enter the body through the intestine, as well as recognizing endogenous antigens. Immune cells in the liver have a complex regulation that can be impaired in various diseases such as metabolic dysfunction-associated steatotic liver disease (MASLD), liver cancer, and biliary diseases. A growing body of evidence reinforces the realization that not only impaired metabolism but also many immune mechanisms underlie MASLD. The liver has complex bilateral immune and metabolic links with the gut microbiota, and disruptions of these links underlie the development and progression of both gastrointestinal and other organ diseases. In this regard, acting on immune mechanisms is a promising therapeutic target for liver diseases.