Porphyromonas gingivalis promotes murine abdominal aortic aneurysms via matrix metalloproteinase-2 induction

BACKGROUND AND OBJECTIVE: Abdominal aortic aneurysm (AAA) is a common and lethal disorder, and MMPs are highly expressed in AAA lesions. Large numbers of periodontopathic bacteria have been reported to be present in specimens obtained from the aortic walls of patients with an AAA. The purpose of this study was to analyze the influence of periodontopathic bacteria on AAA dilatation. MATERIAL AND METHODS: AAAs were produced in mice by the periaortic application of 0.25 M CaCl(2), and NaCl was used as a control. The mice were inoculated once weekly with live Porphyromonas gingivalis, live Aggregatibacter actinomycetemcomitans or vehicle. RESULTS: Four weeks after the periaortic application of either CaCl(2) or NaCl, a significant increase was observed in the aortic diameter of P. gingivalis-challenged mice compared with the vehicle control mice (p < 0.05), whereas there was no statistically significant increase in the aortic diameter of the A. actinomycetemcomitans-challenged mice. Immunohistochemical analysis found significantly higher numbers of CD8-positive and MOMA2-positive cells and significantly higher levels of MMP-2 in the aneurysmal samples of P. gingivalis-challenged mice compared with control mice. Live P. gingivalis promoted a significant proliferation of splenocytes in comparison with P. gingivalis-lipopolysaccharide and live A. actinomycetemcomitans (p < 0.05). CONCLUSION: These findings demonstrate that challenge with P. gingivalis, but not with A. actinomycetemcomitans, can accelerate, or even initiate, the progression of experimental AAA through the increased expression of MMPs.