title: Oral malodorous compound causes caspase-8 and -9 mediated programmed cell death in osteoblasts.
abstract: OBJECTIVE
  Hydrogen sulfide (H(2) S) is one of two volatile sulfur compounds that are known to be the main cause of oral malodor; the other is methyl mercaptan. Other known volatiles existing in mouth air do not contribute significantly to oral malodor originating in the oral cavity. Hydrogen sulfide is also known to be an etiological factor in periodontal disease. However, the effects of H(2) S on alveolar bone remain unclear. The objectives of this study were to determine the apoptotic effects of H(2) S on osteoblasts and to verify the apoptotic molecular pathways.
  
  
  METHODS
  A clonal murine calvaria cell line was incubated with 50 ng/mL of H(2) S. To detect apoptosis, the cells were analysed by flow cytometry and ELISA. Mitochondrial membrane depolarization was assessed using flow cytometry as well. ELISA was used to evaluate the release of cytochrome c into the cytosol and to assess Fas ligand, p53, tumor necrosis factor α, interleukin IL1-α IL-β, IL-2, IL-4, IL-10, interferon-γ, granulocyte-colony stimulating factor and granulocyte-macrophage colony stimulating factor. Caspase-3, -8 and -9 activities were estimated. Expression of BAX and Bcl-2 was assessed by real-time quantitative RT-PCR. DNA fragmentation was detected by single-cell gel electrophoresis. Fas receptors were evaluated by western blotting.
  
  
  RESULTS
  After H(2) S incubation, apoptotic levels increased significantly in a time-dependent manner. Mitochondrial membrane depolarization, the release of cytochrome c, p53 and caspase-3, -8 and -9 and DNA fragmentation were all significantly greater. BAX gene activity was upregulated, whereas Bcl-2 remained low. Fas ligand/Fas receptor, tumor necrosis factor α and other cytokines were not increased to a significant degree.
  
  
  CONCLUSIONS
  At less-than-pathological concentrations in gingival crevicular fluid, H(2) S induces apoptosis in osteoblasts. The molecular mechanisms underlying the apoptotic process include p53, a mitochondrial pathway and caspase-8 activation.
authors.affiliation: Department of Oral Health, The Nippon Dental University, Tokyo, Japan.
authors.forename: I
authors.initials: I
authors.lastname: Aoyama
authors.forename: B
authors.initials: B
authors.lastname: Calenic
authors.forename: T
authors.initials: T
authors.lastname: Imai
authors.forename: H
authors.initials: H
authors.lastname: Ii
authors.forename: K
authors.initials: K
authors.lastname: Yaegaki
mesh_terms: D016475:3T3 Cells; D000818:Animals; D017209:Apoptosis / Q000187:drug effects*; D053148:Caspase 3 / Q000187:drug effects; D053181:Caspase 8 / Q000187:drug effects*; D053453:Caspase 9 / Q000187:drug effects*; D045304:Cytochromes c / Q000187:drug effects; D053938:DNA Fragmentation / Q000187:drug effects; D053222:Fas Ligand Protein / Q000187:drug effects; D016179:Granulocyte Colony-Stimulating Factor / Q000187:drug effects; D016178:Granulocyte-Macrophage Colony-Stimulating Factor / Q000187:drug effects; D006209:Halitosis / Q000378:metabolism*; D006862:Hydrogen Sulfide / Q000009:adverse effects*; D007371:Interferon-gamma / Q000187:drug effects; D016753:Interleukin-10 / Q000032:analysis; D053582:Interleukin-1alpha / Q000032:analysis; D053583:Interleukin-1beta / Q000187:drug effects; D007376:Interleukin-2 / Q000032:analysis; D015847:Interleukin-4 / Q000032:analysis; D053078:Membrane Potential, Mitochondrial / Q000187:drug effects; D051379:Mice; D010006:Osteoblasts / Q000187:drug effects*; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000187:drug effects; D014409:Tumor Necrosis Factor-alpha / Q000187:drug effects; D016159:Tumor Suppressor Protein p53 / Q000187:drug effects; D055549:Volatile Organic Compounds / Q000009:adverse effects; D051028:bcl-2-Associated X Protein / Q000187:drug effects; D019014:fas Receptor / Q000187:drug effects
chemical_list: D053222:Fas Ligand Protein; D053582:Interleukin-1alpha; D053583:Interleukin-1beta; D007376:Interleukin-2; D019253:Proto-Oncogene Proteins c-bcl-2; D014409:Tumor Necrosis Factor-alpha; D016159:Tumor Suppressor Protein p53; D055549:Volatile Organic Compounds; D051028:bcl-2-Associated X Protein; D019014:fas Receptor; D016753:Interleukin-10; D016179:Granulocyte Colony-Stimulating Factor; D015847:Interleukin-4; D007371:Interferon-gamma; D016178:Granulocyte-Macrophage Colony-Stimulating Factor; D045304:Cytochromes c; D053148:Caspase 3; D053181:Caspase 8; D053453:Caspase 9; D006862:Hydrogen Sulfide