Beyond bone remodeling–emerging functions of osteoprotegerin in host defense and microbial infection

Abstract

Osteoprotegerin (OPG), a member of the tumor necrosis factor (TNF) receptor superfamily, suppresses osteoclast formation by preventing the binding of receptor activator of nuclear factor-kappa B ligand (RANKL) to receptor activator of NF-kappa B (RANK). Recent studies indicate that RANKL plays a critical role in the regulation of dendritic cells and macrophages. Indeed, RANK-RANKL interactions on these immune cells are involved in core host defense mechanisms against tumors and infection. Thus, OPG is thought to exert its effects by interfering with the RANKL-RANK interaction. While the role of OPG in bone metabolism are well described, little is known about its role in host defense. This review summarizes current knowledge about the role of OPG in pathologies such as cancer and microbial infections.