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Updated: Aug 16, 2026
Induction of Periodontitis via a Combination of Ligature and Lipopolysaccharide Injection in a Rat Model
Published on: February 17, 2023
P. gingivalis activates the NADPH/PAD4 axis to drive macrophage extracellular trap formation and alveolar bone loss
Aodi Li1, Yuwen Huang1, Siying Li1
1School of Stomatology, Southwest Medical University, Luzhou, Sichuan 646000, China; Luzhou Key Laboratory of Oral & Maxillofacial Reconstruction and Regeneration, The Affiliated Stomatology Hospital, Southwest Medical University, Luzhou, Sichuan 646000, China; Department of Chengbei Outpatient, The Affiliated Stomatology Hospital, Southwest Medical University, Luzhou, Sichuan 646000, China.
Background:
Macrophage extracellular traps (METs) exert dual roles in inflammatory diseases, yet their formation and regulation in periodontitis remain unclear. In particular, whether and how Porphyromonas gingivalis (P. gingivalis) triggers MET formation, and the underlying signaling pathways, have yet to be elucidated.
Methods:
Experimental periodontitis was established in mice by ligation and local P. gingivalis administration, and assessed for bone resorption, inflammatory infiltration, and MET-like accumulation by micro-CT, H&E and immunofluorescence (IF). P. gingivalis -stimulated RAW264.7 cells were detected for MET-like formation and ROS. The role of METs was further probed in vivo using GSK484 or DNase I to block or clear METs.
Results:
Mice with experimental periodontitis showed marked alveolar bone resorption, increased inflammatory infiltration, and enhanced MET accumulation in periodontal tissues. P. gingivalis induced MET release from RAW264.7 cells in a time-dependent manner, accompanied by ROS accumulation and increased histone H3 citrullination. DPI treatment reduced ROS levels, concomitantly inhibiting citrullinated histone H3 (Cit-H3) expression and MET-like formation. The GSK484 treatment did not affect the generation of ROS, but it did markedly suppress the production of Cit-H3 and the release of MET-like. In vivo, both GSK484 and DNase I treatment reduced MET-like accumulation, diminished inflammatory infiltration, suppressed osteoclast activation, and alleviated alveolar bone loss.
Conclusions:
P. gingivalis promotes the MET-like formation through the NADPH/PAD4 axis, thereby amplifying local inflammation and alveolar bone loss in periodontitis.
Insights
Porphyromonas gingivalis promotes macrophage extracellular traps (METs) formation via the NADPH/PAD4 pathway, worsening periodontitis inflammation and bone loss. Blocking METs reduces these effects.
Area of Science:
- Immunology
- Microbiology
- Periodontology
Background:
- Macrophage extracellular traps (METs) have complex roles in inflammatory diseases.
- The specific mechanisms of MET formation and regulation in periodontitis are not well understood.
- The role of Porphyromonas gingivalis (P. gingivalis) in triggering METs and its signaling pathways in periodontitis require elucidation.
Purpose of the Study:
- To investigate the role of P. gingivalis in inducing MET formation in periodontitis.
- To identify the signaling pathways involved in P. gingivalis-induced MET formation.
- To evaluate the therapeutic potential of targeting METs in experimental periodontitis.
Main Methods:
- Experimental periodontitis was induced in mice using P. gingivalis.
- MET formation, reactive oxygen species (ROS), and histone H3 citrullination were assessed.
- Inhibitors of ROS (DPI), PAD4 (GSK484), and METs (DNase I) were used in vitro and in vivo.
Main Results:
- P. gingivalis induced MET formation, ROS production, and histone H3 citrullination in vitro.
- ROS inhibition reduced histone H3 citrullination and MET formation.
- PAD4 inhibition suppressed histone H3 citrullination and MET formation without affecting ROS.
- In vivo, blocking METs reduced inflammation, osteoclast activation, and alveolar bone loss.
Conclusions:
- P. gingivalis promotes MET-like formation via the NADPH/PAD4 axis.
- METs amplify local inflammation and alveolar bone loss in periodontitis.
- Targeting the NADPH/PAD4/MET axis may be a therapeutic strategy for periodontitis.
