Reduction in P. gingivalis - F. nucleatum virulence by cranberry fraction

Background: P. gingivalis and F. nucleatum are considered as important pathogens in the pathogenesis of periodontal disease. We have previously showed that P. gingivalis and F. nucleatum mixed infection induces a stronger inflammatory response than mono-infection. Inhibition of co-aggregation between these bacteria augments the observed response. NDM, an anti-adhesion fraction prepared from cranberry juice, was suggested as a potential interferer of the bacterial virulence. Objectives: To investigate the effect of NDM on the local inflammatory response evoked by mixed infection of P. gingivalis and F. nucleatum in a mouse model. Methods: P. gingivalis, F. nucleatum and their mixture were injected into subcutaneous chambers previously implanted in mice. The effect of the NDM was measured by using the same bacterial challenge with the addition of NDM. The content of the chambers were collected at different time intervals and levels of TNFα, IL-1β, IL-10 and IFNγ were measured. NDM effect on co-aggregation between F. nucleatum and P. gingivalis was determined in vitro prior to the animal experiments. Results: NDM inhibits co-aggregation between P. gingivalis and F. nucleatum in vitro. NDM alone augmented the levels of all the tested cytokines. In mono infected chambers with either P. gingivalis or F. nucleatum the cytokine levels Changed in a similar pattern. However, NDM was found to reduce the inflammatory cytokines in mixed infection. The observed effect was more prominent on IFNγ than IL-10. Conclusions: The results indicated that NDM is a mild immunogenic inducer, with or without mono-species infection. In mixed infection NDM reduces the inflammatory response and shifts it to a more Th2 dominance. The reduction in the virulence of the F. nucleatum and P. gingivalis mixed infection may be due to the anti-adhesion property of NDM.