title: Irsogladine maleate inhibits Porphyromonas gingivalis-mediated expression of toll-like receptor 2 and interleukin-8 in human gingival epithelial cells.
abstract: OBJECTIVE
  Periodontitis is an infectious disease caused by an interaction between the host and periodontopathogenic bacteria. Regulating the immune response in human gingival epithelial cells (HGEC) may contribute to the prevention of periodontitis. Irsogladine maleate (IM) has previously been shown to regulate inflammation and the cell-cell junctional barrier in HGEC. In addition to these functions, control of bacterial recognition is important for preventing inflammation in periodontal tissue. Innate immunity in gingival epithelium is the first line of defense and plays a crucial role against bacterial challenge. Therefore, the effect of IM on regulating toll-like receptor 2 (TLR2), which is part of the innate immunity, was determined in this study.
  
  
  METHODS
  OBA-9, an immortalized human gingival epithelial cell line, and primary cultured HGEC were used in this study. Real-time PCR and western blotting were performed in OBA-9 or HGEC stimulated with whole cells of Porphyromonas gingivalis or with lipopolysaccharide (LPS) derived from P. gingivalis (PgLPS) in the presence or absence of IM to determine expression of TLR2 mRNA and production of TLR2 protein. Small interfering RNA (siRNA) against TLR2 was transfected into OBA-9 to clarify the association between the induction of TLR2 and interleukin-8 (IL-8) production.
  
  
  RESULTS
  The addition of IM into P. gingivalis or PgLPS-induced OBA-9 suppressed IL-8 production (p < 0.01). The addition of IM also abolished the induction of TLR2 by P. gingivalis or PgLPS in OBA-9 and primary cultured HGEC (p < 0.01). The suppressive effect of IM on the induction of TLR2 was also confirmed by immunohistostaining. Stimulation with peptidoglycan, a specific ligand for TLR2, suppressed the expression of toll-like receptor 4 (TLR4) mRNA in the presence of IM (p < 0.01). However, LPS derived from Escherichia coli, a ligand for TLR4, did not induce the expression of TLR2 mRNA. The PgLPS-induced expression of TLR4 mRNA was abolished by IM. Knockdown of TLR2 by siRNA transfection resulted in a weaker response of induction of IL8 mRNA in P. gingivalis or PgLPS-stimulated OBA-9.
  
  
  CONCLUSIONS
  These results suggest that IM suppresses the induction of IL-8 production by regulating increased levels of TLR2.
authors.affiliation: Department of Periodontal Medicine, Division of Applied Life Sciences, Institute of Biomedical & Health Sciences, Hiroshima University, Hiroshima, Japan.
authors.forename: I J
authors.initials: IJ
authors.lastname: Savitri
authors.affiliation: Department of Periodontal Medicine, Division of Applied Life Sciences, Institute of Biomedical & Health Sciences, Hiroshima University, Hiroshima, Japan.
authors.forename: K
authors.initials: K
authors.lastname: Ouhara
authors.affiliation: Department of Periodontal Medicine, Division of Applied Life Sciences, Institute of Biomedical & Health Sciences, Hiroshima University, Hiroshima, Japan.
authors.forename: T
authors.initials: T
authors.lastname: Fujita
authors.affiliation: Department of Periodontal Medicine, Division of Applied Life Sciences, Institute of Biomedical & Health Sciences, Hiroshima University, Hiroshima, Japan.
authors.forename: M
authors.initials: M
authors.lastname: Kajiya
authors.affiliation: Department of Periodontal Medicine, Division of Applied Life Sciences, Institute of Biomedical & Health Sciences, Hiroshima University, Hiroshima, Japan.
authors.forename: T
authors.initials: T
authors.lastname: Miyagawa
authors.affiliation: Department of Periodontal Medicine, Division of Applied Life Sciences, Institute of Biomedical & Health Sciences, Hiroshima University, Hiroshima, Japan.
authors.forename: M
authors.initials: M
authors.lastname: Kittaka
authors.affiliation: Department of Periodontal Medicine, Division of Applied Life Sciences, Institute of Biomedical & Health Sciences, Hiroshima University, Hiroshima, Japan.
authors.forename: M
authors.initials: M
authors.lastname: Yamakawa
authors.affiliation: Department of Periodontal Medicine, Division of Applied Life Sciences, Institute of Biomedical & Health Sciences, Hiroshima University, Hiroshima, Japan.
authors.forename: H
authors.initials: H
authors.lastname: Shiba
authors.affiliation: Department of Periodontal Medicine, Division of Applied Life Sciences, Institute of Biomedical & Health Sciences, Hiroshima University, Hiroshima, Japan.
authors.forename: H
authors.initials: H
authors.lastname: Kurihara
mesh_terms: D002460:Cell Line; D002478:Cells, Cultured; D004847:Epithelial Cells / Q000187:drug effects; D055785:Gene Knockdown Techniques; D005881:Gingiva / Q000166:cytology / Q000187:drug effects*; D006801:Humans; D007113:Immunity, Innate / Q000187:drug effects; D007166:Immunosuppressive Agents / Q000494:pharmacology*; D016209:Interleukin-8 / Q000187:drug effects*; D008070:Lipopolysaccharides / Q000276:immunology / Q000494:pharmacology; D016966:Porphyromonas gingivalis / Q000276:immunology*; D034741:RNA, Small Interfering / Q000235:genetics; D051195:Toll-Like Receptor 2 / Q000187:drug effects* / Q000235:genetics; D014227:Triazines / Q000494:pharmacology*
chemical_list: C508606:CXCL8 protein, human; D007166:Immunosuppressive Agents; D016209:Interleukin-8; D008070:Lipopolysaccharides; D034741:RNA, Small Interfering; C495342:TLR2 protein, human; D051195:Toll-Like Receptor 2; D014227:Triazines; C041836:irsogladine
keywords: Porphyromonas gingivalis; human gingival epithelial cell; irsogladine maleate; toll-like receptor 2