ApoE knockout mice challenged with P. gingivalis also expressed TLR2 and TLR4 in aortic tissue [39], while challenge with an invasion-impaired P. gingivalis fimbriae-deficient mutant did not upregulate TLRs, suggesting that innate immune recognition of invasive bacteria is a prerequisite for the acceleration of atherosclerosis. Here, TLR4 is linked to atherosclerosis.