Diagnostic roles and mechanisms of serum IL-33 in liver diseases: A narrative review of recent progress.

Interleukin-33 (IL-33) belongs to the interleukin-1 (IL-1) family of cytokines. Under physiological conditions, IL-33 is abundant in the nucleus of epithelial cells from barrier tissues, epithelial cells of blood vessels, and fibroblast-like cells. Upon pathological stimulation, such as cell damage or tissue injury, IL-33 is released from these cells and binds to the ST2 receptor, a member of the toll-like receptor (TLR)/IL-1 receptor superfamily. The IL-33/ST2 axis is involved in regulating multiple inflammatory diseases, tissue damage, fibrosis, and the development of cancers. Recent studies have suggested that IL-33 plays a pivotal role as a mediator in liver diseases. Therefore, the aberrantly expressed IL-33/ST2 axis could be a diagnostic biomarker and therapeutic target in liver diseases. In this review, we summarize the expression characteristics, mechanisms, and targeted strategies of IL-33 in hepatitis B virus (HBV) infection, acute or chronic toxic liver injury, steatohepatitis, fibrosis, cirrhosis, hepatic ischemia/reperfusion injury, and hepatocellular carcinoma.