title: The distribution and expression of S100A8 and S100A9 in gingival epithelium of mice.
abstract: OBJECTIVE
  Gingival epithelium protects against bacterial infection by producing antimicrobial peptides such as calprotectin. Calprotectin consists of proteins S100A8 and S100A9. Although in vitro assay has shown that neutrophils and gingival epithelial cells express calprotectin, the expression of S100A8 and S100A9 and colocalization of both S100 proteins in gingival tissue in vivo are not fully understood. The aim of this study was to investigate the distribution of S100A8 and S100A9 expression in gingival epithelium of mice in the presence and absence of infection.
  
  
  METHODS
  A quantitative analysis of S100A8 and S100A9 mRNA in junctional epithelium (JE) and oral gingival epithelium (OGE) of both germ-free mice and conventional mice was performed using laser microdissection and real-time polymerase chain reaction (PCR). Confirmation of S100A8 and S100A9 mRNA expression in the JE was conducted by fluorescent immunohistochemistry.
  
  
  RESULTS
  Real-time PCR analysis indicated that S100A8 and S100A9 expressions were mainly detected in JE and only slightly or not detected in OGE. Levels of both S100A8 and S100A9 mRNA expression in JE of conventional mice were significantly higher than those in JE of germ-free mice. Additionally, fluorescent immunohistochemistry showed that S100A8 expression was observed in the JE of both conventional and germ-free mice, whereas S100A9 was expressed in the JE of conventional but not germ-free mice.
  
  
  CONCLUSIONS
  S100A8 protein is expressed in JE cells of mice in the presence and in the absence of infection with oral bacteria. S100A9 expression in JE cells in the presence of microflora is significantly increased compared with the absence of microflora, which suggests that S100A9 expression may be induced by infection of microflora. The production of calprotectin in gingival epithelial cells may be mediated through S100A9 induction by bacterial infection.
authors.affiliation: Department of Periodontology, Showa University School of Dentistry, Ohta-ku, Tokyo, Japan.
authors.forename: K
authors.initials: K
authors.lastname: Nishii
authors.forename: M
authors.initials: M
authors.lastname: Usui
authors.forename: G
authors.initials: G
authors.lastname: Yamamoto
authors.forename: S
authors.initials: S
authors.lastname: Yajima
authors.forename: Y
authors.initials: Y
authors.lastname: Tsukamoto
authors.forename: J
authors.initials: J
authors.lastname: Tanaka
authors.forename: T
authors.initials: T
authors.lastname: Tachikawa
authors.forename: M
authors.initials: M
authors.lastname: Yamamoto
mesh_terms: D000818:Animals; D040501:Calgranulin A / Q000032:analysis*; D040502:Calgranulin B / Q000032:analysis*; D016207:Cytokines / Q000032:analysis*; D004846:Epithelial Attachment / Q000033:anatomy & histology; D004847:Epithelial Cells / Q000166:cytology; D004848:Epithelium / Q000033:anatomy & histology; D005260:Female; D005455:Fluorescent Antibody Technique; D005856:Germ-Free Life; D005881:Gingiva / Q000033:anatomy & histology* / Q000166:cytology / Q000382:microbiology; D053685:Laser Therapy; D051379:Mice; D008813:Mice, Inbred ICR; D042282:Microdissection; D009504:Neutrophils / Q000166:cytology; D060888:Real-Time Polymerase Chain Reaction; D019707:Receptors, Chemokine / Q000032:analysis
chemical_list: D040501:Calgranulin A; D040502:Calgranulin B; D016207:Cytokines; C503133:Gr-1 protein, mouse; D019707:Receptors, Chemokine; C576329:S100A9 protein, mouse; C086145:S100a8 protein, mouse