Tannerella forsythia and Fusobacterium nucleatum cooperate to induce synergistic periodontal bone destruction
El Hassan, Ahmed Taher
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Tannerella forsythia is a Gram-negative anaerobic bacterium strongly implicated in the development of chronic periodontitis (PD). T. forsythia is a late colonizer of the dental plaque that participates in plaque biofilm formation with the help of other cohabiting bacteria such as Fusobacterium nucleatum . In the present study, we were interested in determining the extent to which T. forsythia -induced inflammatory responses and alveolar bone destruction were impacted by the cohabiting bacterial species F. nucleatum. For this purpose, BALB/cJ mice were infected repeatedly by the oral route for two weeks with either T. forsythia, F. nucleatum or both T. forsythia and F. nucleatum . Six weeks following the last infection, mice were sacrificed and horizontal bone loss in the alveolar bones was assessed. ELISA was performed to assess the levels of cytokines in different groups. In addition, bone histochemical staining to quantify the numbers of osteoclasts in alveolar bones and immunohistochemistry to quantify the numbers of inflammatory cells in gingival tissues of the infected and control mice was performed. Our results showed that the mixed infection with T. forsythia and F. nucleatum synergistically increased alveolar bone loss in comparison to the alveolar bone loss due to the mono-infection of T. forsythia , or F. nucleatum alone. The levels of cytokines, the numbers of osteoblast and inflammatory cells were also found to be increased in the mixed infection group compared to the mono-infection groups.