title: Treponema denticola suppresses expression of human beta-defensin-2 in gingival epithelial cells through inhibition of TNFalpha production and TLR2 activation.
abstract: We previously reported that Treponema denticola, a periodontal pathogen, suppressed the expression of human beta-defensins (HBDs) and IL-8 in human gingival epithelial cells. To clarify the receptor(s) involved in the suppression of HBD-2, immortalized gingival epithelial (HOK-16B) cells were infected with live or heat-killed T. denticola for 24 h, and the expression of HBD-2 was examined by real-time RT-PCR. Live T. denticola, but not heat-killed bacteria, suppressed the expression of HBD-2 about 40%. Time courses of suppression revealed that T. denticola suppressed HBD-2 expression only at late time points, which was accompanied with the suppression of TNFalpha production. Neutralization of TNFalpha with an antibody abrogated the suppressive effect of T. denticola on HBD-2. Accordingly, heat-killed T. denticola did not suppress TNFalpha production. Knock-down of toll-like receptor (TLR) 2 via RNA interference reversed the suppressive effect of T. denticola on the expression of HBD-3, but not on the production of TNFalpha. Collectively, T. denticola suppresses the expression of HBD-2 in gingival epithelial cells by inhibiting the TLR2 axis and TNFalpha production, which may contribute to the pathogenesis of periodontitis by T. denticola.
authors.affiliation: Department of Oromaxillofacial Infection and Immunity, Brain Korea 21 CLS, School of Dentistry and Dental Research Institute, Seoul National University, Seoul, 110-749, Korea.
authors.forename: Ji Eun
authors.initials: JE
authors.lastname: Shin
authors.forename: Youngnim
authors.initials: Y
authors.lastname: Choi
mesh_terms: D001428:Bacterial Vaccines / Q000276:immunology; D002460:Cell Line; D004797:Enzyme-Linked Immunosorbent Assay; D004847:Epithelial Cells / Q000378:metabolism* / Q000382:microbiology; D015870:Gene Expression; D005881:Gingiva / Q000166:cytology; D054884:Host-Pathogen Interactions; D006801:Humans; D034622:RNA Interference; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013997:Time Factors; D051195:Toll-Like Receptor 2 / Q000235:genetics* / Q000378:metabolism; D048373:Treponema denticola / Q000254:growth & development* / Q000276:immunology / Q000502:physiology; D014409:Tumor Necrosis Factor-alpha / Q000235:genetics* / Q000378:metabolism; D023083:beta-Defensins / Q000235:genetics* / Q000378:metabolism
chemical_list: D001428:Bacterial Vaccines; C106641:DEFB4A protein, human; C495342:TLR2 protein, human; D051195:Toll-Like Receptor 2; D014409:Tumor Necrosis Factor-alpha; D023083:beta-Defensins