MCP-1 is induced by receptor activator of nuclear factor-{kappa}B ligand, promotes human osteoclast fusion, and rescues granulocyte macrophage colony-stimulating factor suppression of osteoclast formation.
Human osteoclast formation from monocyte precursors under the action of receptor activator of nuclear factor-kappaB ligand (RANKL) was suppressed by granulocyte macrophage colony-stimulating factor (GM-CSF), with down-regulation of critical osteoclast-related nuclear factors. GM-CSF in the presence of RANKL and macrophage colony-stimulating factor resulted in mononuclear cells that were negative for tartrate-resistant acid phosphatase (TRAP) and negative for bone resorption. CD1a, a dendritic cell marker, was expressed in GM-CSF, RANKL, and macrophage colony-stimulating factor-treated cells and absent in osteoclasts. Microarray showed that the CC chemokine, monocyte chemotactic protein 1 (MCP-1), was profoundly repressed by GM-CSF. Addition of MCP-1 reversed GM-CSF suppression of osteoclast formation, recovering the bone resorption phenotype. MCP-1 and chemokine RANTES (regulated on activation normal T cell expressed and secreted) permitted formation of TRAP-positive multinuclear cells in the absence of RANKL. However, these cells were negative for bone resorption. In the presence of RANKL, MCP-1 significantly increased the number of TRAP-positive multinuclear bone-resorbing osteoclasts (p = 0.008). When RANKL signaling through NFATc1 was blocked with cyclosporin A, both MCP-1 and RANTES expression was down-regulated. Furthermore, addition of MCP-1 and RANTES reversed the effects of cyclosporin A and recovered the TRAP-positive multinuclear cell phenotype. Our model suggests that RANKL-induced chemokines are involved in osteoclast differentiation at the stage of multinucleation of osteoclast precursors and provides a rationale for increased osteoclast activity in inflammatory conditions where chemokines are abundant.
Kim
Michael S
MS
School of Medical Science, Griffith University Gold Coast Campus, Queensland 4215, Australia.
Day
Christopher J
CJ
Morrison
Nigel A
NA
D002352:Carrier Proteins / Q000378:metabolism*; D002454:Cell Differentiation / Q000502:physiology; D002459:Cell Fusion; D018932:Chemokine CCL2 / Q000378:metabolism*; D004268:DNA-Binding Proteins / Q000378:metabolism; D018628:Gene Dosage; D016178:Granulocyte-Macrophage Colony-Stimulating Factor / Q000378:metabolism*; D006801:Humans; D008562:Membrane Glycoproteins / Q000378:metabolism*; D009000:Monocytes / Q000166:cytology / Q000378:metabolism; D050778:NFATC Transcription Factors; D009687:Nuclear Proteins / Q000378:metabolism; D010010:Osteoclasts / Q000166:cytology / Q000378:metabolism*; D053245:RANK Ligand; D053246:Receptor Activator of Nuclear Factor-kappa B; D014157:Transcription Factors / Q000378:metabolism
C111835:CCL2 protein, human; D002352:Carrier Proteins; D018932:Chemokine CCL2; D004268:DNA-Binding Proteins; D008562:Membrane Glycoproteins; D050778:NFATC Transcription Factors; C494003:NFATC1 protein, human; D009687:Nuclear Proteins; D053245:RANK Ligand; D053246:Receptor Activator of Nuclear Factor-kappa B; C505686:TNFRSF11A protein, human; C505688:TNFSF11 protein, human; D014157:Transcription Factors; D016178:Granulocyte-Macrophage Colony-Stimulating Factor