Liver Immunology

The human liver is usually perceived as a non-immunological organ engaged primarily in metabolic, nutrient storage and detoxification activities. The healthy liver is also a site of complex immunological activity mediated by a diverse immune cell repertoire as well as non-hematopoietic cell populations. In the non-diseased liver, metabolic and tissue remodeling functions require elements of inflammation. In this complex microenvironment, the hepatic immune system tolerates harmless molecules while at the same time remaining alert to possible infectious agents, malignant cells or tissue damage.

In the healthy liver, constantly changing metabolic and tissue remodeling activity, combined with regular exposure to microbial products, results in persistent, regulated inflammation. These inflammatory processes act in a tightly controlled fashion and are stimulated to additional activity only when the liver is required to rid itself of hepatotropic pathogens, malignant cells or toxic products of metabolic activity. Failure to clear such dangerous stimuli and resolve inflammation, leads to chronic infection, autoimmunity or tumor growth. This is inevitably associated with chronic pathological inflammation and disrupted tissue homeostasis, which can progress to fibrosis, cirrhosis and liver failure.