title: TLR2-dependent modulation of osteoclastogenesis by Porphyromonas gingivalis through differential induction of NFATc1 and NF-kappaB.
abstract: Osteolytic diseases, including rheumatoid arthritis, osteomyelitis, and periodontitis, are usually associated with bacterial infections. However, the precise mechanisms by which bacteria induce bone loss still remain unclear. Evidence exists that Toll-like receptor (TLR) signaling regulates both inflammation and bone metabolism and that the receptor activator of NF-κB ligand (RANKL) and its receptor RANK are the key regulators for bone remodeling and for the activation of osteoclasts. Here, we investigate the direct effects of the periodontal pathogen Porphyromonas gingivalis on osteoclast differentiation and show that P. gingivalis differentially modulates RANKL-induced osteoclast formation contingent on the state of differentiation of osteoclast precursors. In addition, although an optimal induction of cytokines by P. gingivalis is dependent on TLR2 and TLR4, as well as myeloid differentiation factor 88 and Toll/IL-1R domain-containing adaptor-inducing IFN-β, P. gingivalis utilizes TLR2/ myeloid differentiation factor 88 in modulating osteoclast differentiation. P. gingivalis modulates RANKL-induced osteoclast formation by differential induction of NFATc1 and c-Fos. More importantly, RANKL-mediated lineage commitment also has an impact on P. gingivalis-induced cytokine production. RANKL inhibits P. gingivalis-induced cytokine production by down-regulation of TLR/NF-κB and up-regulation of NFATc1. Our findings reveal novel aspects of the interactions between TLR and RANK signaling and provide a new model for understanding the mechanism underlying the pathogenesis of bacteria-mediated bone loss.
authors.affiliation: Department of Pediatric Dentistry, University of Alabama at Birmingham, Birmingham, Alabama 35294, USA. pingz@uab.edu
authors.forename: Ping
authors.initials: P
authors.lastname: Zhang
authors.forename: Jianzhong
authors.initials: J
authors.lastname: Liu
authors.forename: Qingan
authors.initials: Q
authors.lastname: Xu
authors.forename: Gregory
authors.initials: G
authors.lastname: Harber
authors.forename: Xu
authors.initials: X
authors.lastname: Feng
authors.forename: Suzanne M
authors.initials: SM
authors.lastname: Michalek
authors.forename: Jenny
authors.initials: J
authors.lastname: Katz
mesh_terms: D000818:Animals; D016866:Bacteroidaceae Infections / Q000235:genetics / Q000276:immunology / Q000378:metabolism*; D002454:Cell Differentiation; D016899:Interferon-beta / Q000235:genetics / Q000276:immunology / Q000378:metabolism; D051379:Mice; D018345:Mice, Knockout; D053594:Myeloid Differentiation Factor 88 / Q000235:genetics / Q000276:immunology / Q000378:metabolism; D016328:NF-kappa B / Q000235:genetics / Q000276:immunology / Q000378:metabolism*; D050778:NFATC Transcription Factors / Q000235:genetics / Q000276:immunology / Q000378:metabolism*; D010010:Osteoclasts / Q000276:immunology / Q000378:metabolism*; D016966:Porphyromonas gingivalis / Q000276:immunology / Q000378:metabolism*; D016760:Proto-Oncogene Proteins c-fos / Q000235:genetics / Q000276:immunology / Q000378:metabolism; D053245:RANK Ligand; D015398:Signal Transduction / Q000235:genetics / Q000276:immunology; D051195:Toll-Like Receptor 2 / Q000235:genetics / Q000276:immunology / Q000378:metabolism*; D051197:Toll-Like Receptor 4 / Q000235:genetics / Q000276:immunology / Q000378:metabolism*
chemical_list: C507780:Myd88 protein, mouse; D053594:Myeloid Differentiation Factor 88; D016328:NF-kappa B; D050778:NFATC Transcription Factors; C494005:Nfatc1 protein, mouse; D016760:Proto-Oncogene Proteins c-fos; D053245:RANK Ligand; C493486:Tlr2 protein, mouse; C493487:Tlr4 protein, mouse; C505689:Tnfsf11 protein, mouse; D051195:Toll-Like Receptor 2; D051197:Toll-Like Receptor 4; D016899:Interferon-beta