Porphyromonas gingivalis infection and prothrombotic effects in human aortic smooth muscle cells

Introduction: Accumulating evidence has demonstrated an association between periodontal infectious agents, such as Porphyromonas gingivalis, and vascular disease. Tissue factor (TF) and its specific tissue factor pathway inhibitor (TFPI) are produced by vascular cells and are important regulators of the coagulation cascade. Materials and Methods: To assess the role of P. gingivalis in atherothrombosis, we infected primary human aortic smooth muscle cells (HASMC) with either P. gingivalis 381, its non-invasive mutant DPG3, or heat-killed P. gingivalis 381. Levels and activity of TF and TFPI were measured 8 and 24 hours after infection in cell extracts and cell culture supernatants. Results: P. gingivalis 381 did not affect total TF antigen or TF activity in HASMC, but it significantly suppressed TFPI levels and activity compared to uninfected control cells, and those infected with the non-invasive mutant strain or the heat-killed bacteria. Further, P. gingivalis' LPS (up to a concentration of 5 μg/ml) failed to induce prothrombotic effects in HASMC, suggesting a significant role for the ability of whole viable bacteria to invade this cell type. Conclusion: These data demonstrate for the first time that infection with a periodontal pathogen induces a prothrombotic response in HASMC.