ObjectivesRecent studies have reported that periodontal disease increases the risk of atherosclerosis. We previously reported that Porphyromonas gingivalis (Pg) accelerated atherosclerotic plaque formation in hyperlipidemic apoE-/- mice by initiating inflammation. Because the oxidative modification of lipoprotein plays a major role in atherosclerosis, we characterized the reactive oxygen species (ROS) produced by Pg and its ability to oxidize low-density lipoprotein (LDL). MethodsAtherosclerotic plaque formation in the aortic sinuses of Apoeshl mice injected intravenously with Pg 381 was assessed by Oil Red O staining. Anti-mouse antibodies to HOCl-oxidized LDL and 4-HNE, PLA2, MPO, and CD36 were used for immunohistochemistry. Intracellular ROS detection was performed using 2′,7′-dichlorodihydrofluorescein diacetate. Quantitative reverse transcription polymerase chain reaction was performed using primers specific for TLR-2, TLR-4, TLR-9, NOD-1, LOX-1, NOX-2, NOX-4, p22phox, and p47phox. ResultsPg challenge significantly induced ox-LDL and 4-HNE-, PLA2-, MPO-, and CD36-positive areas in proximal aortic lesions. TLR-2, TLR-4, NOD-1, LOX-1, and NADPH oxidase subunit-specific mRNA levels in the aorta were significantly increased. Furthermore, Pg significantly induced ROS production in monocytes. ConclusionsThese results suggest that Pg promotes LDL oxidation and contributes to atheroma development.