Porphyromonas gingivalis infection enhances Th17 responses for development of atherosclerosis

•Porphyromonas gingivalis is associated with the acceleration of atherosclerosis.•Atherosclerosis involves T cell-related chronic inflammatory responses.•Recent studies indicate that Th17 cells have been correlated with the emergence of atherosclerosis.•P. gingivalis infection may accelerate atherosclerosis via increasing of Th17 responses.

ObjectivesPorphyromonas gingivalis has been shown to associate with the development of atherosclerosis. Recent studies indicate that IL-17-producing T helper 17 (Th17) cells have been correlated with the emergence of atherosclerosis. Therefore, we investigated whether the Th17 cell response and expression of Th17-related molecules, in contrast with Th1- and Treg cells, are enhanced by P. gingivalis-challenge in Apolipoprotein E knockout (ApoE KO) mice.DesignFive mice were intravenously injected with P. gingivalis three times a week for 3 weeks and killed at 15 weeks of age. The proximal aorta lesion area, flow cytometry analysis and IL-17, IL-10, IFN-γ, and IL-1β levels in splenic cultures, and expression of Th17-related molecules in spleen and hearts were examined.ResultsP. gingivalis-challenge showed notable accumulation of atherosclerotic plaques by Oil Red O-staining in ApoE KO mice. Intracellular cytokine staining revealed that significantly elevated CD4+ interleukin (IL)-17A+ T cells and slightly increased CD4+ Foxp3+ T cells was recognized in spleen cells of P. gingivalis-challenged mice compared with those from non-infected mice. P. gingivalis-challenge significantly increased IL-17 and IL-1β production and RORγt expression in splenic cells. Furthermore, the expression of Th17-related genes such as IL-6, TGF-β, RORγt and STAT3 were elevated in splenic cells as well as heart tissue of P. gingivalis-challenged mice.ConclusionThese results suggest that P. gingivalis infection may enhance pro-inflammatory Th17 cell responses in lesion areas and spleen, thereby accelerating atherosclerosis.