TLR4 and atherosclerosis: Several Gram-negative bacteria that express immune-evasive lipid A species are associated with an increased risk of atherosclerosis (133, 134), but the oral pathogen P. gingivalis is a striking example of how lipid A variants allow a bacterium to evade TLR4 and promote chronic inflammation through dysregulation of both innate and adaptive immune responses (71, 78–80, 135).