Quorum Sensing Molecule Autoinducer-2 Promotes Macrophage Classical Polarization and Exacerbates Periodontal Inflammation Via Nf-Κb Signalling.

BACKGROUND

The role of quorum sensing signaling in the immunoinflammatory response during the development of periodontitis is not yet known. This study aimed to explore the effect of Autoinducer-2, a quorum sensing signaling molecule, on macrophage phenotypic remodeling in the immune microenvironment of periodontitis, to further elucidate its mechanism and to discover inhibitors against periodontitis.

METHODS

Bioluminescence experiments and periodontitis model were used to demonstrate the association between periodontitis progression with AI-2. Next, AI-2 challenged macrophage was introduced to transcriptomic sequence and the immune profile was characterized in combination with flow cytometry, qPCR, and immunofluorescence. Activation of NF-κB signalling by AI-2 was confirmed by fluorescence co-localization and immunoblotting. Finally, morphological methods such as Micro-CT and HE, TRAP staining and immunological methods such as immunohistochemistry/fluorescence staining were used to assess the mechanisms by which AI-2 regulates periodontitis progression.

RESULTS

AI-2 level was positively correlated with the progression of periodontitis stages and was significantly higher in periodontitis stage III and IV patients. AI-2 promotes macrophage classical polarization and facilitates the secretion of inflammatory factors in vitro, which is dependent on the activation of the NF-κB signaling pathway. AI-2 promotes alveolar bone resorption, but D-ribose acts as a quorum sensing inhibitor to alleviate macrophage classical polarization and attenuates alveolar bone resorption and inflammatory responses in periodontitis mice.

CONCLUSIONS

Our study demonstrates that AI-2 promoted classical polarization of macrophage and exacerbated periodontal inflammation which could be reversed by D-ribose.