title: Induction of toll-like receptor expression by Porphyromonas gingivalis.
abstract: BACKGROUND
  Toll-like receptors (TLRs) play pivotal roles in host immune responses and have been suggested to be involved in the development of many infectious diseases. In this study, the mRNA expression levels of TLR2, TLR4, and TLR9 and their relationship with periodontopathic bacteria in periodontal tissue are examined. Furthermore, the mechanism of TLR induction by Porphyromonas gingivalis is investigated in human gingival fibroblasts (HGFs).
  
  
  METHODS
  Gingival tissue and subgingival plaque samples were collected from 19 patients with chronic periodontitis (CP) and 16 control individuals without periodontitis. Gene expression levels in the tissues and in HGFs were analyzed by reverse transcription-polymerase chain reaction (RT-PCR). The numbers of periodontopathic bacteria were determined by quantitative real-time PCR.
  
  
  RESULTS
  The expression levels of TLR2 and TLR9 were significantly higher in the tissues of patients with CP compared to the tissues of control individuals. The mRNA levels of TLR2 and TLR9, but not TLR4, were positively correlated with the number of P. gingivalis in subgingival plaque. P. gingivalis sonicated extract, P. gingivalis lipopolysaccharide, P. gingivalis DNA, and tumor necrosis factor-α(TNF-α) could significantly upregulate the mRNA expression of TLR2 in HGFs. Furthermore, P. gingivalis-mediated TLR2 expression was suppressed by TNF-α antibody.
  
  
  CONCLUSIONS
  This study suggests that P. gingivalis infection induces TLR2 and TLR9 upregulation in patients with CP. P. gingivalis-induced TLR2 expression in HGFs is partially dependent on TNF-α and may lead to sensitization of HGFs to bacterial components encountered in the periodontal microenvironment.
authors.affiliation: Department of Periodontology, Faculty of Dentistry, Khon Kaen University, Khon Kaen, Thailand. nawarat@kku.ac.th
authors.forename: Nawarat
authors.initials: N
authors.lastname: Wara-aswapati
authors.forename: Anek
authors.initials: A
authors.lastname: Chayasadom
authors.forename: Rudee
authors.initials: R
authors.lastname: Surarit
authors.forename: Waranuch
authors.initials: W
authors.lastname: Pitiphat
authors.forename: Jason A
authors.initials: JA
authors.lastname: Boch
authors.forename: Toshiyuki
authors.initials: T
authors.lastname: Nagasawa
authors.forename: Isao
authors.initials: I
authors.lastname: Ishikawa
authors.forename: Yuichi
authors.initials: Y
authors.lastname: Izumi
mesh_terms: D000328:Adult; D016976:Aggregatibacter actinomycetemcomitans / Q000302:isolation & purification; D058491:Bacterial Load; D001431:Bacteriological Techniques; D018929:Cell Culture Techniques; D055113:Chronic Periodontitis / Q000276:immunology / Q000382:microbiology; D004269:DNA, Bacterial / Q000494:pharmacology; D003773:Dental Plaque / Q000276:immunology / Q000382:microbiology; D005260:Female; D005347:Fibroblasts / Q000276:immunology / Q000382:microbiology; D005881:Gingiva / Q000382:microbiology / Q000473:pathology; D006801:Humans; D008070:Lipopolysaccharides / Q000494:pharmacology; D008297:Male; D008875:Middle Aged; D017622:Periodontal Attachment Loss / Q000276:immunology / Q000382:microbiology; D010514:Periodontal Pocket / Q000276:immunology / Q000382:microbiology; D016966:Porphyromonas gingivalis / Q000276:immunology* / Q000302:isolation & purification; D060888:Real-Time Polymerase Chain Reaction; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013347:Subcellular Fractions / Q000276:immunology; D051195:Toll-Like Receptor 2 / Q000276:immunology*; D051197:Toll-Like Receptor 4 / Q000276:immunology*; D051217:Toll-Like Receptor 9 / Q000276:immunology*; D014409:Tumor Necrosis Factor-alpha / Q000032:analysis / Q000494:pharmacology; D015854:Up-Regulation
chemical_list: D004269:DNA, Bacterial; D008070:Lipopolysaccharides; C495342:TLR2 protein, human; C495345:TLR4 protein, human; C495371:TLR9 protein, human; D051195:Toll-Like Receptor 2; D051197:Toll-Like Receptor 4; D051217:Toll-Like Receptor 9; D014409:Tumor Necrosis Factor-alpha