Interleukin-15 increases hepatic regenerative activity.

BACKGROUND/AIMS: Interleukin-15 (IL-15) is expressed in many organs. It generally inhibits apoptosis and increases cellular proliferation and differentiation. However, IL-15's roles in liver are unknown. We aimed to determine if IL-15 influences hepatic integrity and regenerative activity. METHODS: Expression of IL-15 and its receptors was evaluated in several liver injury models, primary hepatocytes, and two liver cell lines. Effects of IL-15 on viability, proliferation, and apoptosis were assessed in cultured liver cells, and also in the livers of healthy mice. RESULTS: IL-15 and its receptors are expressed constitutively in healthy livers, and ligand expression is induced in injured livers. Cultured primary hepatocytes and liver cell lines express IL-15 and its receptors. Administration of IL-15 has minimal effects on cultured liver cells, but significantly up-regulates oval cell accumulation, cyclin mRNA expression, and mature hepatocyte replication in healthy mice. These effects are associated with focal hepatic inflammation and increased expression of TNF-alpha and IFN-gamma, but not with increased cell death or aminotransferase release. CONCLUSIONS: IL-15 expression increases during liver injury and IL-15 treatment induces a wound healing-type response in healthy adult mice. These findings suggest that IL-15 may contribute to regenerative activity in damaged liver.

Duke Scholars

Author Ayako Suzuki Medicine, Gastroenterology

Author Shannon Jones McCall Pathology

Author Steven Sok Choi Medicine, Gastroenterology

Author Anna Mae Diehl Medicine, Gastroenterology