Porphyromonas gingivalis platelet aggregation activity: outer membrane vesicles are potent activators of murine platelets

Recent evidence has established an association between chronic periodontiti s and cardiovascular disease. Periodontitis is a chronic inflammatory disea se caused by a small group of gram-negative bacteria, of which Porphyromona s gingivalis is considered an important causative agent. It has been propos ed that dental plaque bacteria and their products can disseminate into the bloodstream from the site of infection and promote thromboembolic events as sociated with atherosclerosis and myocardial infarction. In this regard, St reptococcus sanguis and P, gingivalis have been shown to induce platelet ag gregation in vitro. Here we report that P. gingivalis was able to induce pl atelet aggregation, and that oral strains of Actinobaillus actinomycetemcom itans, Bacteroides forsythus, Campylobacter rectus, Fusobacterium nucleatum , Prevotella intermedia and Trepenoma denticola failed to aggregate platele ts when tested for platelet aggregation activity under similar conditions. Additionally, we show that vesicles (outer membrane evaginations that are s hed into the environment by the bacteria) of P. gingivalis are potent induc ers of mouse platelet aggregation in vitro. In summary, our data show that i) initial adherence of the bacterium to platelet may be facilitated by P. gingivalis fimbriae and ii) P. gingivalis vesicles possess platelet aggrega tion-inducing activity.