FXR in bone metabolism: An emerging regulator.

Farnesoid X receptor (FXR), a core regulator of bile acid metabolism, is also a key modulator of bone metabolism that influences bone remodeling by regulating osteoblast and osteoclast activities. FXR activation promotes the proliferation and differentiation of osteoblasts via pathways such as Wnt/β-catenin, and inhibits osteoclastogenesis through the NF-κB pathway and the RANK/OPG balance. It also regulates chondrocyte function and cartilage integrity, inhibits cartilage-degrading MMP-13, coordinates subchondral bone remodeling to maintain joint health, and acts as a metabolic hub linking the gut, liver, and bone by integrating bile acid and systemic metabolic signals. Dysregulation of this pathway is associated with skeletal complications of non-alcoholic fatty liver disease (NAFLD), obesity and other disorders, and intestinal FXR-mediated FGF15/19 signaling also maintains skeletal homeostasis. FXR activation is a promising therapeutic target for preserving bone density by improving metabolism and alleviating inflammation. This review elucidates its regulatory mechanisms in bone metabolism, laying a foundation for relevant research and translational applications.