title: T cells support osteoclastogenesis in an in vitro model derived from human periodontitis patients.
abstract: BACKGROUND
  Periodontitis is characterized by alveolar bone destruction; however, the mechanisms responsible for bone damage are poorly understood. It has been reported that T cells are implicated in the pathogenesis of periodontitis. It has been also demonstrated that activated T lymphocytes secrete receptor activator of nuclear factor-kappa B ligand (RANKL) and can support the differentiation of monocytes into resorbing osteoclasts (OCs). Therefore, the purpose of this study was to examine the OC formation in periodontitis patients (PP) and the role of T cells in osteoclastogenesis.
  
  
  METHODS
  To study OC formation, we used an in vitro model consisting of unstimulated and unfractionated peripheral blood mononuclear cells (PBMCs) from PP and controls. In parallel, T-cell-depleted PBMCs from the same patients were also established. The expression of RANKL and tumor necrosis factor-alpha (TNF-alpha) was analyzed by reverse transcription-polymerase chain reaction (RT-PCR) and Western blot in fresh T cells isolated from PP and controls. Functional antibodies, anti-RANKL and anti-TNF-alpha, were utilized to study osteoclastogenesis in PBMC cultures from PP.
  
  
  RESULTS
  We showed that, in unfractionated PBMCs from PP, the OCs spontaneously developed in a T-cell-dependent way. The addition of macrophage colony stimulating factor (MCSF) and RANKL was necessary to promote the osteoclastogenesis in T-cell-depleted PBMC cultures from PP and in unfractionated PBMCs from periodontally healthy controls. Moreover, freshly isolated T cells from PBMCs of PP overexpressed RANKL and TNF-alpha. Finally, functional anti-RANKL and anti-TNF-alpha antibodies significantly inhibited osteoclastogenesis.
  
  
  CONCLUSIONS
  Our data suggest that T cells support spontaneous osteoclastogenesis in PP via RANKL and TNF-alpha overexpression.
authors.affiliation: Department of Human Anatomy and Histology, University of Bari, Bari, Italy.
authors.forename: G
authors.initials: G
authors.lastname: Brunetti
authors.forename: S
authors.initials: S
authors.lastname: Colucci
authors.forename: P
authors.initials: P
authors.lastname: Pignataro
authors.forename: M
authors.initials: M
authors.lastname: Coricciati
authors.forename: G
authors.initials: G
authors.lastname: Mori
authors.forename: N
authors.initials: N
authors.lastname: Cirulli
authors.forename: A
authors.initials: A
authors.lastname: Zallone
authors.forename: F R
authors.initials: FR
authors.lastname: Grassi
authors.forename: M
authors.initials: M
authors.lastname: Grano
mesh_terms: D000328:Adult; D015153:Blotting, Western; D002352:Carrier Proteins / Q000096:biosynthesis / Q000494:pharmacology / Q000502:physiology; D016022:Case-Control Studies; D002454:Cell Differentiation; D002478:Cells, Cultured; D005260:Female; D006801:Humans; D016173:Macrophage Colony-Stimulating Factor / Q000096:biosynthesis / Q000494:pharmacology / Q000502:physiology; D008297:Male; D008562:Membrane Glycoproteins / Q000096:biosynthesis / Q000494:pharmacology / Q000502:physiology; D009000:Monocytes / Q000187:drug effects; D009504:Neutrophils / Q000187:drug effects / Q000378:metabolism; D010010:Osteoclasts / Q000166:cytology*; D010518:Periodontitis / Q000276:immunology*; D053245:RANK Ligand; D053246:Receptor Activator of Nuclear Factor-kappa B; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013601:T-Lymphocytes / Q000378:metabolism / Q000502:physiology*; D014409:Tumor Necrosis Factor-alpha / Q000096:biosynthesis / Q000494:pharmacology / Q000502:physiology
chemical_list: D002352:Carrier Proteins; D008562:Membrane Glycoproteins; D053245:RANK Ligand; D053246:Receptor Activator of Nuclear Factor-kappa B; C505686:TNFRSF11A protein, human; C505688:TNFSF11 protein, human; D014409:Tumor Necrosis Factor-alpha; D016173:Macrophage Colony-Stimulating Factor