title: Interleukin-17A stimulates granulocyte-macrophage colony-stimulating factor release by murine osteoblasts in the presence of 1,25-dihydroxyvitamin D(3)  and inhibits murine osteoclast development in vitro.
abstract: OBJECTIVE
  To investigate the effects of interleukin-17A (IL-17A) on osteoclastogenesis in vitro.
  
  
  METHODS
  Bone marrow cells (BMCs) were isolated from the excised tibia and femora of wild-type C57BL/6J mice, and osteoblasts were obtained by sequential digestion of the calvariae of ddY, C57BL/6J, and granulocyte-macrophage colony-stimulating factor-knockout (GM-CSF(-/-)) mice. Monocultures of BMCs or cocultures of BMCs and osteoblasts were supplemented with or without 1,25-dihydroxyvitamin D(3)(1,25[OH](2)D(3)), recombinant human macrophage colony-stimulating factor (M-CSF), RANKL, and IL-17A. After 5-6 days, the cultures were fixed with 4% paraformaldehyde and subsequently stained for the osteoclast marker enzyme tartrate-resistant acid phosphatase (TRAP). Osteoprotegerin (OPG) and GM-CSF expression were measured by enzyme-linked immunosorbent assay, and transcripts for RANK and RANKL were detected by real-time polymerase chain reaction.
  
  
  RESULTS
  In both culture systems, IL-17A alone did not affect the development of osteoclasts. However, the addition of IL-17A plus 1,25(OH)(2)D(3) to cocultures inhibited early osteoclast development within the first 3 days of culture and induced release of GM-CSF into the culture supernatants. Furthermore, in cocultures of GM-CSF(-/-) mouse osteoblasts and wild-type mouse BMCs, IL-17A did not affect osteoclast development, corroborating the role of GM-CSF as the mediator of the observed inhibition of osteoclastogenesis by IL-17A.
  
  
  CONCLUSIONS
  These findings suggest that IL-17A interferes with the differentiation of osteoclast precursors by inducing the release of GM-CSF from osteoblasts.
authors.affiliation: Bern University Hospital and University of Bern, Bern, Switzerland.
authors.forename: Deepak
authors.initials: D
authors.lastname: Balani
authors.forename: Daniel
authors.initials: D
authors.lastname: Aeberli
authors.forename: Willy
authors.initials: W
authors.lastname: Hofstetter
authors.forename: Michael
authors.initials: M
authors.lastname: Seitz
mesh_terms: D000818:Animals; D002117:Calcitriol / Q000494:pharmacology*; D002452:Cell Count; D002454:Cell Differentiation / Q000187:drug effects / Q000502:physiology*; D002478:Cells, Cultured; D016178:Granulocyte-Macrophage Colony-Stimulating Factor / Q000378:metabolism*; D020381:Interleukin-17 / Q000494:pharmacology*; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D010006:Osteoblasts / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D010010:Osteoclasts / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D053244:Osteoprotegerin / Q000378:metabolism
chemical_list: D020381:Interleukin-17; D053244:Osteoprotegerin; D016178:Granulocyte-Macrophage Colony-Stimulating Factor; D002117:Calcitriol