RANKL/RANK signaling in rheumatoid arthritis

Rheumatoid arthritis (RA) is a chronic inflammatory disease, which is induced by abundant inflammatory cytokines releasing from synovial fibroblasts and T lymphocytes. These cytokines differentiate monocyte-macrophage lineage cells to mature osteoclasts, which cause bone resorption and then joint destruction. RANKL is involved in the development of osteoclasts, cooperating with another key molecule, M-CSF. Indeed, RANKL is over-expressed in the synovium of RA. We summarize RANKL/RANK signaling in RA, including recent therapeutic topics.