title: T-cells mediate an inhibitory effect of interleukin-4 on osteoclastogenesis.
abstract: IL-4 is an important cytokine that can influence bone. We identified two distinct actions of IL-4 to inhibit osteoclast formation: one direct on osteoclast progenitors and the second through the production of a novel T-cell surface-associated molecule(s). These data show a new link between the immune system and bone. The Th2 cytokine interleukin (IL)-4 inhibits osteoclast formation in vitro but also acts on other cell types found in bone, including T-cells and macrophages. Because some osteoclastogenesis inhibitors (e.g., IL-12) act indirectly through T-cells, we investigated IL-4 action on osteoclastogenesis in the presence of T-cells. Osteoclast formation from murine spleen cells treated with RANKL and macrophage colony-stimulating factor (M-CSF) was blocked by IL-4 even when spleen cells were depleted of T-cells (Thy 1.2+) and/or B-cells (B220+). Also, IL-4 inhibited osteoclastogenesis in RANKL/M-CSF-stimulated adherent spleen cells, Rag1 -/- (lymphocyte-deficient) spleen cells, and bone marrow macrophages, indicating an action on myelomonocytic cells to block osteoclastogenesis. In contrast, IL-4 did not inhibit osteoclastogenesis in cells from IL-4 receptor null mice (IL-4R -/-). However, when wildtype T-cells were added to IL-4R -/- spleen cell cultures, IL-4 inhibited osteoclast formation, indicating a T-cell-dependent action. Osteoclast formation in RANKL-stimulated RAW 264.7 cells was not inhibited by IL-4 unless T-cells were added to the culture. Separation of RAW 264.7 cells and T-cells by semipermeable membrane ablated this action of IL-4, suggesting the induction of a membrane-associated osteoclastogenesis inhibitor. However, membrane-bound inhibitors thymic shared antigen-1 (TSA-1) and osteoclast inhibitory lectin (OCIL) were not regulated by IL-4. In summary, at least two mechanisms of IL-4 -mediated osteoclastogenesis inhibition exist, including a direct action on myelomonocytic progenitors (from which osteoclasts derive) and an indirect action through T-cells that may involve novel anti-osteoclastic factors.
authors.affiliation: St. Vincent's Institute of Medical Research, Fitzroy, Victoria, Australia.
authors.forename: Danijela
authors.initials: D
authors.lastname: Mirosavljevic
authors.forename: Julian M W
authors.initials: JM
authors.lastname: Quinn
authors.forename: Jan
authors.initials: J
authors.lastname: Elliott
authors.forename: Nicole J
authors.initials: NJ
authors.lastname: Horwood
authors.forename: T John
authors.initials: TJ
authors.lastname: Martin
authors.forename: Matthew T
authors.initials: MT
authors.lastname: Gillespie
mesh_terms: D000818:Animals; D001483:Base Sequence; D002352:Carrier Proteins / Q000494:pharmacology; D002460:Cell Line; D017931:DNA Primers; D015847:Interleukin-4 / Q000172:deficiency / Q000235:genetics / Q000502:physiology*; D008212:Lymphocyte Depletion; D016173:Macrophage Colony-Stimulating Factor / Q000494:pharmacology; D008297:Male; D008562:Membrane Glycoproteins / Q000494:pharmacology; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D010010:Osteoclasts / Q000187:drug effects / Q000276:immunology / Q000502:physiology*; D053245:RANK Ligand; D053246:Receptor Activator of Nuclear Factor-kappa B; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013154:Spleen / Q000187:drug effects / Q000276:immunology; D013601:T-Lymphocytes / Q000187:drug effects / Q000276:immunology*; D018418:Th2 Cells / Q000276:immunology
chemical_list: D002352:Carrier Proteins; D017931:DNA Primers; D008562:Membrane Glycoproteins; D053245:RANK Ligand; D053246:Receptor Activator of Nuclear Factor-kappa B; C505687:Tnfrsf11a protein, mouse; C505689:Tnfsf11 protein, mouse; D015847:Interleukin-4; D016173:Macrophage Colony-Stimulating Factor