Innate Immune Recognition of Invasive Bacteria Accelerates Atherosclerosis in Apolipoprotein E-Deficient Mice

Background— Infectious diseases have emerged as potential risk factors for cardiovascular disease (CVD). Epidemiological studies support a connection between periodontal disease, a chronic inflammatory disease of the supporting tissues of the teeth, and CVD. Methods and Results— To directly test the connection between periodontal disease and atherosclerosis, apoE −/− mice were orally challenged with the periodontal disease pathogen Porphyromonas gingivalis or an invasion-impaired P gingivalis fimbriae-deficient mutant (FimA−). Both wild-type P gingivalis and the FimA− mutant were detected in blood and aortic arch tissue of apoE −/− mice by PCR after challenge. ApoE −/− mice challenged with wild-type P gingivalis presented with increased atherosclerotic plaque and expressed the innate immune response markers Toll-like receptor (TLR)-2 and TLR-4 in aortic tissue. Despite detection of the FimA− mutant in the blood and in aortic arch tissue, apoE −/− mice challenged with the FimA− mutant did not present with periodontal disease, upregulation of TLRs, or accelerated atherosclerosis. Furthermore, we demonstrate that immunization to control P gingivalis -elicited periodontal disease concomitantly prevents P gingivalis -accelerated atherosclerosis. Conclusions— We conclude that invasive P gingivalis accelerates atherosclerosis.