Skip to main content
. Author manuscript; available in PMC: 2019 Mar 1.
Published in final edited form as: Nat Rev Rheumatol. 2018 Jan 11;14(3):146–156. doi: 10.1038/nrrheum.2017.213

Figure 3. Purinergic signalling regulates bone cells and inflammation.

Figure 3

ATP signals through members of the P2X receptor family of ligand-gated ion channels. Mechanical loading regulates the release of ATP and prostaglandin E2 (PGE2) by osteoblasts and osteocytes. Extracellular ATP signals through P2X7 or P2X5 on immature osteoclasts, triggering cell fusion and resulting in multi-nucleated osteoclasts. ATP also triggers the production of pro inflammatory cytokines such as IL 6 by synovial fibroblasts, and can synergize with lipopolysaccharide (LPS) signalling through Toll like receptors (TLRs) to activate inflammasomes and produce mature forms of IL 1β and IL 18 that also promote osteoclast multi nucleation and maturation. In an experimental setting, LPS triggered inflammatory bone loss requires purinergic signalling through the P2X5 receptor.