title: Porphyromonas gingivalis Suppresses Differentiation and Increases Apoptosis of Osteoblasts From New Zealand Obese Mice.
abstract: BACKGROUND
  Metabolic syndrome (MetS), a complex cluster of risk factors for chronic diseases such as cardiovascular disease, is observed to be increasingly associated with periodontal disease. However, the fundamental contribution of periodontal bacteria to periodontal bone loss in patients with MetS remains unclear. The aim of the present study is to analyze the effect of Porphyromonas gingivalis on differentiation of primary osteoblasts from New Zealand obese (NZO) mice, a model for MetS, compared with C57 Black 6 JAX (C57BL/6J) mice osteoblasts.
  
  
  METHODS
  Primary calvarial osteoblasts, isolated from 3-day-old NZO and control C57BL/6J mice, were stimulated with P. gingivalis. Proliferation was quantified by 5-bromo-2'-deoxyuridine incorporation. Cell cycle and early and late apoptosis were measured by flow cytometry. Gene expression was determined by real-time polymerase chain reaction (RT-PCR).
  
  
  RESULTS
  Twelve hours after P. gingivalis stimulation, NZO osteoblasts showed significantly decreased proliferation (P ≤0.01) with increased G2 cell cycle phase compared with normal osteoblasts. Flow cytometry analysis demonstrated significant (P ≤0.01) increase of early apoptotic cells (annexin V positive) and late apoptosis (caspase 3 activity) in NZO cells compared with control cells at 3 and 6 hours after stimulation. No significant lactate dehydrogenase release was found after P. gingivalis stimulation. RT-PCR data showed significantly suppressed expression (P ≤0.01) of collagen 1, osteocalcin, and Runt-related transcription factor 2 in NZO cells compared with normal osteoblasts.
  
  
  CONCLUSIONS
  The present data demonstrate that P. gingivalis downregulates proliferation and promotes apoptosis in primary NZO osteoblasts, unlike C57BL/6J osteoblasts. Also, suppressed osteoblastic marker expression in NZO cells may contribute to pathogenesis of periodontitis, suggesting a similar process in patients with MetS.
authors.affiliation: Department of Periodontology and Synoptic Dentistry, Charité-Medical University of Berlin, Germany.
authors.forename: Cora
authors.initials: C
authors.lastname: Dittmann
authors.affiliation: Department of Periodontology and Synoptic Dentistry, Charité-Medical University of Berlin, Germany.
authors.forename: Salim
authors.initials: S
authors.lastname: Doueiri
authors.affiliation: Max-Rubner-Laboratory, German Institute of Human Nutrition Potsdam-Rehbrücke, Nuthetal, Germany.
authors.forename: Reinhart
authors.initials: R
authors.lastname: Kluge
authors.affiliation: Department of Periodontology and Synoptic Dentistry, Charité-Medical University of Berlin, Germany.
authors.forename: Henrik
authors.initials: H
authors.lastname: Dommisch
authors.affiliation: Department of Rheumatology and Clinical Immunology, Charité University Hospital, Berlin, Germany.
authors.forename: Timo
authors.initials: T
authors.lastname: Gaber
authors.affiliation: Department of Periodontology and Synoptic Dentistry, Charité-Medical University of Berlin, Germany.
authors.forename: Nicole
authors.initials: N
authors.lastname: Pischon
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000502:physiology; D053148:Caspase 3 / Q000032:analysis; D002454:Cell Differentiation / Q000502:physiology; D049109:Cell Proliferation; D002478:Cells, Cultured; D024042:Collagen Type I / Q000032:analysis; D000090602:Collagen Type I, alpha 1 Chain; D050659:Core Binding Factor Alpha 1 Subunit / Q000032:analysis; D004195:Disease Models, Animal; D015536:Down-Regulation; D005260:Female; D016195:G2 Phase / Q000502:physiology; D006023:Glycoproteins / Q000032:analysis; D007770:L-Lactate Dehydrogenase / Q000032:analysis; D008297:Male; D024821:Metabolic Syndrome / Q000382:microbiology; D051379:Mice; D008810:Mice, Inbred C57BL; D008815:Mice, Inbred Strains; D008820:Mice, Obese; D010006:Osteoblasts / Q000382:microbiology*; D015675:Osteocalcin / Q000032:analysis; D010518:Periodontitis / Q000382:microbiology; D016966:Porphyromonas gingivalis / Q000502:physiology*; D013997:Time Factors
chemical_list: D024042:Collagen Type I; D000090602:Collagen Type I, alpha 1 Chain; D050659:Core Binding Factor Alpha 1 Subunit; D006023:Glycoproteins; C493717:Runx2 protein, rat; C029490:nephrocalcin; D015675:Osteocalcin; D007770:L-Lactate Dehydrogenase; C505409:Casp3 protein, mouse; D053148:Caspase 3
keywords: Alveolar bone loss; Porphyromonas gingivalis; metabolic syndrome X; mice; obesity; osteoblasts