Aggregation of Human Platelets by Tannerella Forsythia

CONTEXT: Periodontitis is a persistent infection of the tissues surrounding the teeth characterized by inflamed microvasculature, and is associated with increased systemic platelet activation. AIMS: The purpose of this study was to assess the in vitro platelet aggregating potential of the red-complex bacterium Tannerella forsythia. A second-related objective was to ascertain the in vitro effect of dual platelet inhibitors on T. forsythia-platelet interaction. SETTINGS AND DESIGN: These ex vivo experiments were done in a basic science laboratory combining isolated human platelets with isolated bacterial cells. METHODS: Dilutions of cells were counted by quantitative polymerase chain reaction. Aggregation was assayed in a platelet aggregometer after adding cells or sonic extracts to gel filtered platelets, some of which were preincubated with the dual platelet inhibitors aspirin plus clopidogrel. RESULTS: Platelets aggregate in vitro when exposed to T. forsythia cells or sonic extracts and dilution results in increased lag times and decreased aggregation. Platelets preincubated with the combination of aspirin plus clopidogrel do not aggregate in response to T. forsythia. CONCLUSIONS: Within the limitations of this in vitro study, T. forsythia cells aggregate human platelets and the activity can be attenuated by diluting the cells and blocked by the combination of aspirin plus clopidogrel.