Mechanisms of Inflammasome Activation and Involvement in Liver Disease

The liver is a multi-potent organ with important metabolic, immunological and endocrine functions. Hepatic physiology is maintained at a balanced state via the delicate actions of different liver-resident cells. Among several factors that modulate hepatic physiology, the harmony between the activity of pro- and anti-inflammatory cytokines is a crucial determinant. However, initiation of inflammatory activity can be detrimental if it goes unresolved, leading to severe consequences such as hepatitis, hepatic fibrosis, cirrhosis or even hepatocellular carcinoma (HCC). Different physiological processes can modulate the hepatic microenvironment; one such factor is a cytosolic protein complex called the inflammasome. Inflammasome activation is a consequence of the cellular encounter with pathogens or products of cellular damage. Once activated, inflammasomes promote the maturation of interleukin-1 family cytokines such as IL-1β and IL-18 via activation of caspase-1. These cytokines have a very potent role in modulating hepatic physiology. Various lines of reports suggest that inflammasome activation and IL-1 cytokines play critical roles in liver diseases, including hepatitis, hepatic fibrosis and HCC. Conversely, inhibition of inflammasome activation and/or IL-1 signaling prevents such effects. This review summarizes the mechanisms leading to inflammasome activation and the role it plays in hepatic physiology.