Porphyromonas gingivalis induces myocarditis and/or myocardial infarction in mice and IL-17A is involved in pathogenesis of these diseases

Objectives: Although an association between periodontitis and cardiovascular diseases has been suggested, the role of Porphyromonas gingivalis in cardiovascular diseases is not clear. In this study, we examined whether experimental bacteremia of P. gingivalis causes cardiovascular diseases and investigated the mechanism of pathogenesis of cardiovascular diseases induced by P. gingivalis. Design: C57B1./6 mice were intravenously inoculated with 2.0 x 10(8) CFU of P. gingivalis A7436 strain. Mice were sacrificed at specified days and their hearts were collected. The collected organs were divided into two halves and used for histological evaluation and cytolcine analysis. IL-17A(-/-), IFN-gamma(-/-) and TNF-alpha(-/-) mice were also intravenously inoculated and the histological changes of hearts in mice were examined. Results: Myocarditis and/or myocardial infarction were observed in mice injected with P. gin givalis. The levels of IL1-beta, IL-6, IL-17A, IL-18, TNF-alpha and IFN-gamma mRNA increased significantly after P. gin givalis injection. In particular, high levels of IL-17A and IFN-gamma mRNA expression were observed in hearts of mice after P. gin givalis injection in comparison with these levels before injection. Furthermore, the production of IL-17A was detected in hearts of wild-type mice after P. gin givalis injection. In wild-type, TNF-alpha(-/-) and IFN-gamma(-/-) mice, moderate infiltration of neutrophils and monocytes was observed in hearts at 5 days after injection. In contrast, no inflammatory findings were observed in hearts of IL-17A(-/-) mice. Conclusion: We have demonstrated that an experimental bacteremia of P. gin givalis could induce myocarditis and/or myocardial infarction in mice, and IL-17A plays an important role in the pathogenesis of these diseases. (C) 2011 Elsevier Ltd. All rights reserved.