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.