title: Calcium phosphate particles induce interleukin-8 expression in a human gingival epithelial cell line via the nuclear factor-κB signaling pathway.
abstract: BACKGROUND
  Dental calculus is calcified plaque composed primarily of calcium phosphate mineral salts, and there is a clear association between the presence of calculus and the initiation/progression of periodontitis. However, it is still inconclusive whether dental calculus can be a direct causative factor. The authors examined the effect of nano/microsized calcium phosphate particles, which may be generated in the process of early precipitation and/or dissolution of calcium phosphate mineral, on the expression of interleukin (IL)-8 in human gingival epithelial cells.
  
  
  METHODS
  Primary human gingival epithelial cells and/or a human gingival carcinoma cell line (Ca9-22) were stimulated with calcium phosphate particles. Gene and protein levels were assessed by real-time polymerase chain reaction analysis and enzyme-linked immunosorbent assay, respectively. The activity of nuclear factor (NF)-κB signaling was measured by an immunofluorescence assay to evaluate NF-κB p65 nuclear translocation.
  
  
  RESULTS
  The results show that nano/microsized particles stimulate IL-8 expression in human gingival epithelial cells at gene and protein levels. The activity to induce IL-8 expression depends on the particle size: particles with a diameter of 200 nm are more effective than those of 40-nm and 5-μm diameters. Calcium phosphate particles (diameter 200 nm) stimulated NF-κB activity. Pretreatment with BMS-345541, an NF-κB signaling inhibitor, inhibited the particle-mediated IL-8 gene induction, suggesting a requirement for the NF-κB signaling pathway.
  
  
  CONCLUSIONS
  These findings suggest that calcium phosphate particles, which may be related to calculus development, may act as a direct causative factor in the pathogenesis of gingival epithelium.
authors.affiliation: Department of Periodontology and Endodontology, Tohoku University Graduate School of Dentistry, Sendai, Japan.
authors.forename: Yu
authors.initials: Y
authors.lastname: Sakai
authors.forename: Eiji
authors.initials: E
authors.lastname: Nemoto
authors.forename: Sousuke
authors.initials: S
authors.lastname: Kanaya
authors.forename: Mitsuru
authors.initials: M
authors.lastname: Shimonishi
authors.forename: Hidetoshi
authors.initials: H
authors.lastname: Shimauchi
mesh_terms: D000328:Adult; D059587:Calcifying Nanoparticles / Q000494:pharmacology; D002130:Calcium Phosphates / Q000737:chemistry / Q000494:pharmacology*; D018929:Cell Culture Techniques; D002460:Cell Line; D045744:Cell Line, Tumor; D002467:Cell Nucleus / Q000378:metabolism; D002478:Cells, Cultured; D003728:Dental Calculus / Q000737:chemistry; D004305:Dose-Response Relationship, Drug; D017886:Durapatite / Q000737:chemistry / Q000494:pharmacology; D004846:Epithelial Attachment / Q000166:cytology / Q000187:drug effects*; D005260:Female; D005786:Gene Expression Regulation / Q000187:drug effects; D005881:Gingiva / Q000166:cytology / Q000187:drug effects*; D006801:Humans; D007093:Imidazoles / Q000494:pharmacology; D016209:Interleukin-8 / Q000037:antagonists & inhibitors / Q000187:drug effects*; D020935:MAP Kinase Signaling System / Q000502:physiology; D008297:Male; D016328:NF-kappa B / Q000037:antagonists & inhibitors / Q000187:drug effects*; D010316:Particle Size; D011810:Quinoxalines / Q000494:pharmacology; D015398:Signal Transduction / Q000187:drug effects*; D051996:Transcription Factor RelA / Q000187:drug effects; D055815:Young Adult
chemical_list: C471109:4(2'-aminoethyl)amino-1,8-dimethylimidazo(1,2-a)quinoxaline; C508606:CXCL8 protein, human; D059587:Calcifying Nanoparticles; D002130:Calcium Phosphates; D007093:Imidazoles; D016209:Interleukin-8; D016328:NF-kappa B; D011810:Quinoxalines; D051996:Transcription Factor RelA; D017886:Durapatite; C020243:calcium phosphate
keywords: Calcium phosphates; NF-κB; dental calculus; epithelial cells; gingiva; interleukin-8