Apabetalone alleviates ligature-induced periodontitis by inhibiting M1 macrophage polarization via an immunometabolic shift.

OBJECTIVES

To explore the effects and biological mechanism of apabetalone on periodontal inflammation by regulating glycolysis and metabolites.

METHODS

A ligature-induced periodontitis model was established in mice and apabetalone was administered on the ligation silk for two weeks. Inflammation levels and alveolar bone absorption were explored using micro-computed tomography and histopathological analysis. To observe the role of apabetalone in macrophage polarization and the macrophage-mediated immune microenvironment, a Luminex assay, quantitative real-time polymerase chain reaction, a conditioned medium experiment, a Seahorse extracellular flux assay and quantitative metabolomics were used for molecular biological analysis.

RESULTS

Apabetalone-treated mice exhibited ameliorated alveolar bone loss and inflammatory infiltration in the periodontium. Furthermore, apabetalone significantly inhibited the production of proinflammatory cytokines and suppressed the levels of M1-specific biomarkers both in vivo and in vitro. Apabetalone also promoted the osteogenic potential of mouse periodontal ligament cells in a macrophage-mediated microenvironment. Apabetalone restrained LPS-induced glucose uptake and lactic acid production. Apabetalone inhibited glycolysis by suppressing the transcription and protein expression of hexokinase 2, glucose transporter 1 and phosphofructokinase-2/fructose-2,6- bisphosphatase 3 (PFKFB3) in a dose-dependent manner. Quantitative analysis of certain carbohydrates involved in energy metabolism revealed that apabetalone reserved the disruption of the tricarboxylic acid (TCA) cycle and inhibited glycolysis and the pentose phosphate pathway. In addition, apabetalone increased the oxygen consumption rate.

CONCLUSION

Collectively, these findings indicate that apabetalone improves the periodontal immune microenvironment by regulating metabolites in macrophages. Apabetalone exerts anti-inflammatory and osteo-protective effects by replenishing the broken TCA cycle and suppressing glycolysis. Apabetalone is a potential candidate for the treatment of periodontitis.