title: Reciprocal effects of Interferon-γ and IL-4 on differentiation to osteoclast-like cells by RANKL or LPS.
abstract: OBJECTIVE
  LPS can induce differentiation to osteoclast-like cells independent of RANKL. In comparison with RANKL, the effects of Th1 and Th2 cytokines on LPS-induced osteoclastogenesis have not been extensively studied. In this study, we investigated the effects of IFN-γ and IL-4 on RANKL- or LPS-induced osteoclastogenesis.
  
  
  METHODS
  RAW 264.7 cells were induced to differentiate into osteoclast-like cells by RANKL or LPS, in the absence or presence of IFN-γ or IL-4. The number of TRAP-positive, multinucleated (≥ 3 nuclei) cells (MNCs) was counted. mRNA and protein levels of TRAP and cathepsin K were determined by quantitative RT-PCR and Western immunoblot, respectively. Expression of other genes implicated in osteoclast and macrophage differentiation and inflammation was also quantitated and was subsequently assessed in bone marrow-derived macrophages (BMMs). Phagocytic capacity of differentiated RAW264.7 was investigated by the uptake of pHrodo S. aureus bioparticles conjugates.
  
  
  RESULTS
  In contrast to the RANKL-treated cell population that gained more macrophage-like properties at the level of gene and protein expression as well as phagocytosis in the presence of IFN-γ or IL-4, the LPS-induced population gained more osteoclast-like properties by the addition of the same factors.
  
  
  CONCLUSIONS
  These data suggest that the adaptive immune system, through either Th1 or Th2 cytokines, is able to modify the differentiation process of osteoclasts in inflammatory situations. Moreover, the study provides an example of different regulation of osteoclast differentiation during physiological and inflammatory conditions.
authors.affiliation: Institution of Dental Medicine, Qilu Hospital, Shandong University, Jinan, China; Department of Dental Medicine, Division of Oral Biology, Karolinska Institutet, Huddinge, Sweden.
authors.forename: Y
authors.initials: Y
authors.lastname: Hu
authors.forename: B
authors.initials: B
authors.lastname: Ek-Rylander
authors.forename: M
authors.initials: M
authors.lastname: Wendel
authors.forename: G
authors.initials: G
authors.lastname: Andersson
mesh_terms: D000818:Animals; D002454:Cell Differentiation / Q000187:drug effects*; D007371:Interferon-gamma / Q000494:pharmacology*; D015847:Interleukin-4 / Q000494:pharmacology*; D008070:Lipopolysaccharides / Q000494:pharmacology*; D008264:Macrophages / Q000166:cytology / Q000187:drug effects; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D010010:Osteoclasts / Q000166:cytology* / Q000187:drug effects*; D053245:RANK Ligand / Q000494:pharmacology*
chemical_list: D008070:Lipopolysaccharides; D053245:RANK Ligand; D015847:Interleukin-4; D007371:Interferon-gamma
keywords: IFN-γ; IL-4; LPS; Osteoclasts; RANKL; macrophages; multinucleated cells; tartrate-resistant acid phosphatase