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Updated: Dec 30, 2025
Investigation of Macrophage Polarization Using Bone Marrow Derived Macrophages
Published on: June 23, 2013
NLRP3 inflammasome mediates M1 macrophage polarization and IL-1β production in inflammatory root resorption
Jie Zhang1,2, Xinqiang Liu1,2, Chunyan Wan2,3
1Department of Orthodontics, The Affiliated Hospital of Qingdao University, Qingdao, China.
Aims:
To explore the involvement of NOD-like receptor protein 3 (NLRP3) inflammasome and M1 macrophage in root resorption (RR).
Methods:
A rat RR model was established by excessive orthodontic force. After different force-loading time, the expression levels of NLRP3, caspase-1, and interleukin-1β (IL-1β) and distribution of M1 macrophages were analysed by immunohistochemistry and immunofluorescence staining in vivo. Then, the mechanism of NLRP3 activation was further verified by macrophage and human periodontal ligament cell (hPDLC) co-culture system in vitro. The production levels of NLRP3, caspase-1, pro-caspase-1, and IL-1β in M1 macrophages in the co-culture system were detected by Western blot, and the polarization of CD68+IL-1β+ M1 macrophages was detected by immunofluorescence staining.
Results:
In the rat RR model, NLRP3, caspase-1, IL-1β, and M1 macrophages were expressed in periodontal ligament, mainly concentrated around RR areas. Force-pre-treated hPDLCs promoted M1 macrophage polarization and the production of NLRP3, caspase-1, and IL-1β in M1 macrophages in co-culture system. When MCC950, an inhibitor of NLRP3 inflammasome, was added, NLRP3 activation and M1 macrophage polarization were inhibited.
Conclusions:
In periodontal tissues, hPDLCs stimulated by force promoted M1 macrophage polarization and increased IL-1β production by activating NLRP3 inflammasome in M1 macrophages, thus initiating the occurrence of RR.
Insights
Root resorption (RR) is initiated by orthodontic force stimulating periodontal ligament cells. This promotes M1 macrophage polarization and interleukin-1β (IL-1β) production via NLRP3 inflammasome activation.
Area of Science:
- Biomedical research
- Immunology
- Periodontology
Background:
- Root resorption (RR) is a common complication of orthodontic treatment.
- The precise molecular mechanisms underlying RR, particularly the role of inflammation, require further elucidation.
Purpose of the Study:
- To investigate the involvement of the NOD-like receptor protein 3 (NLRP3) inflammasome and M1 macrophages in the pathogenesis of root resorption.
- To elucidate the cellular and molecular interactions driving RR.
Main Methods:
- Established a rat model of root resorption induced by excessive orthodontic force.
- Analyzed the expression and distribution of NLRP3, caspase-1, IL-1β, and M1 macrophages in vivo using immunohistochemistry and immunofluorescence.
- Utilized a co-culture system of macrophages and human periodontal ligament cells (hPDLCs) to verify the mechanism of NLRP3 activation in vitro, employing Western blot and immunofluorescence staining.
Main Results:
- NLRP3, caspase-1, IL-1β, and M1 macrophages were significantly expressed in periodontal tissues, concentrated around areas of root resorption in the rat model.
- Force-pre-treated hPDLCs enhanced M1 macrophage polarization and the production of NLRP3, caspase-1, and IL-1β in M1 macrophages.
- Inhibition of NLRP3 inflammasome activation using MCC950 suppressed both NLRP3 activation and M1 macrophage polarization.
Conclusions:
- Orthodontic force-induced stimulation of hPDLCs promotes M1 macrophage polarization.
- Activation of the NLRP3 inflammasome in M1 macrophages leads to increased IL-1β production.
- This cascade initiates root resorption, highlighting the NLRP3 inflammasome and M1 macrophages as key players in the process.
