Activation of the NLRP3 inflammasome in Porphyromonas gingivalis-accelerated atherosclerosis

Abstract

Porphyromonas gingivalis has been shown to accelerate atherosclerotic lesion development in hyperlipidemic animals. Atherosclerosis is a disease characterized by inflammation of the arterial wall. Recent studies have suggested that the NLRP3 inflammasome plays an important role in the development of vascular inflammation and atherosclerosis. Herein, we investigated a possible association between the inflammasome in atherosclerosis and periodontal disease induced by P. gingivalis infection using apolipoprotein E-deficient, spontaneously hyperlipidemic (Apoe(shl)) mice. Oral infection with wild-type (WT) P. gingivalis significantly increased the area of aortic sinus covered with atherosclerotic plaque and alveolar bone loss, compared with KDP136 (gingipain-null mutant) or KDP150 (FimA-deficient mutant) challenge. WT challenge also increased IL-1β, IL-18 and TNF-α production in peritoneal macrophages, and gingival or aortic gene expression of Nod-like receptor family, pyrin domain containing 3 (NLRP3), pro-IL-1β, pro-IL-18 and pro-caspase-1. Porphyromonas gingivalis genomic DNA was detected more in the aorta, gingival tissue, liver and spleen of WT-challenged mice than those in KDP136- or KDP150-challenged mice. We conclude that WT P. gingivalis activates innate immune cells through the NLRP3 inflammasome compared with KDP136 or KDP150. The NLRP3 inflammasome may play a critical role in periodontal disease and atherosclerosis induced by P. gingivalis challenge through sustained inflammation.