The glycolytic enzyme PKM2 regulates inflammatory osteoclastogenesis by modulating STAT3 phosphorylation.

Periodontitis is a prevalent chronic inflammatory disease characterized by alveolar bone resorption mediated by osteoclasts. Pyruvate kinase M2 (PKM2), a key enzyme in glycolysis and pyruvate metabolism, has recently been recognized for its regulatory roles beyond metabolism, including gene expression and protein kinase activity. However, its exact role in osteoclastogenesis remains unclear. This study investigates the function of PKM2 in inflammatory osteoclastogenesis and explores its potential as a therapeutic target for periodontitis. Using murine bone marrow-derived macrophages (BMMs) stimulated with lipopolysaccharides (LPS) to mimic inflammatory conditions in vitro, we analyzed PKM2 expression and glycolytic activity during osteoclastogenesis through bioinformatics, tartrate-resistant acid phosphatase (TRAP) staining, phalloidin staining, quantitative real-time PCR (RT-qPCR), and Western blotting. Glycolysis was inhibited using 2-deoxy-D-glucose (2-DG), while TEPP-46 was used to activate PKM2. In a mouse model of periodontitis, the effects of TEPP-46 on alveolar bone loss were evaluated using micro-computed tomography, immunohistochemistry, TRAP staining, and hematoxylin-eosin (HE) staining. The results demonstrated that LPS significantly enhanced osteoclastogenesis and glycolysis, increasing PKM2 expression in osteoclasts. Inhibiting glycolysis with 2-DG suppressed osteoclast formation and osteoclast-related gene expression under inflammatory conditions. TEPP-46 treatment reduced nuclear dimeric PKM2 levels, decreased phosphorylated signal transducer and activator of transcription three (p-STAT3) expression, and inhibited osteoclastogenesis and osteoclast-related gene expression. Co-immunoprecipitation confirmed an interaction between nuclear dimeric PKM2 and p-STAT3. In vivo, TEPP-46 effectively reduced alveolar bone loss by preventing PKM2 nuclear translocation and STAT3 phosphorylation. These findings reveal that PKM2 regulates inflammatory osteoclastogenesis through modulation of glycolysis and STAT3 signaling, highlighting its potential as a therapeutic target for periodontitis.