The Effect of Treponema denticola immunoinhibitory protein on cytokine expression in T cells

Treponema denticola has long been considered as a periodontal pathogen. Listgarten also reported that spirochetes are conspicuous inhabitants of subgingival plaque in patients with gingivitis and periodontitis. Although this bacteria is well known to be important periodontal pathogens, several studies suggest that spirochetes may be involved in pulpal and periapical infections as well. For instance, Thilo et al. reported that the root canal flora of decayed teeth contained as much as 6% of spirochetes. Likewise, Nair reported that the spirochetes form a significant component of the flora of periapical specimen. Recent studies using 16S rDNA-directed polymerase chain reaction (PCR) technique confirmed that the occurrence of Treponema denticola accounted for 52.4% of the flora in infected root canals and 50% in acute alveolar abscesses of endodontic origin. Thus, spirochetes or their byproducts may contribute to the inflammatory process and pathogenesis of the periradicular infection. However, it is not clear how spirochetes are involved in the etiology of the disease. In this regard, Shenker et al. demonstrated that soluble sonic extracts of several strains of T. denticola inhibit human peripheral blood lymphocyte (HPBL) proliferative responses to both mitogen and antigens in vitro with no effect on cell viability. They have also observed that these effects are due to a protein compound The Effect of Treponema denticola immunoinhibitory protein on cytokine expression in T cells