Response of epithelial cells infected by <italic>Treponema denticola</italic>.

Objective: In the gingival crevice, the interaction between epithelial cells and periodontopathic bacteria is important for the development of periodontitis. <italic>Treponema denticola</italic> is a major pathogen of chronic periodontitis and possesses several virulence factors, such as major surface protein (Msp) and prolyl‐phenylalanine‐specific protease (dentilisin). Here, we investigated the behaviours of epithelial cells infected with <italic>T. denticola</italic> by measuring the expression of interleukin (IL)‐1β, IL‐6, β defensin 2 (BD‐2) and heat‐shock protein 70 (HSP70). Methods: Epithelial cells were infected with <italic>T. denticola</italic> wild‐type strain, Msp‐deficient mutant or dentilisin‐deficient mutant, and the expression levels of the above targets were analysed by polymerase chain reaction. Results: Infection with <italic>T. denticola</italic> wild‐type strain and mutants induced the production of IL‐6 and HSP70. The level of BD‐2 induced by <italic>T. denticola</italic> wild‐type strain at 24 hr was significantly higher than that of the dentilisin‐deficient mutant. The level of <italic>IL‐1</italic>β mRNA in the wild‐type strain and dentilisin‐deficient mutant was slightly lower than that in the uninfected control. Conclusion: These results suggest that the levels of BD‐2 were affected by Msp and dentilisin. This effect may contribute to the disruption of the response of epithelial cells to eradicate <italic>T. denticola</italic>. [ABSTRACT FROM AUTHOR]