Inhibition of Dynamin-Related Protein 1-Dependent Mitochondrial Fission Ameliorates Apical Periodontitis by Attenuating NLRP3 Inflammasome-Mediated M1 Macrophage Polarisation
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Updated: Sep 19, 2025
Inducing Apical Periodontitis in Mice
Published on: August 6, 2019
Yao Yang1, Min Li1, Lifei Pan1
1Key laboratory of Shaanxi Province for Craniofacial Precision Medicine Research, College of Stomatology, Xi'an Jiaotong University, Xi'an, Shaanxi, China; Laboratory Center of Stomatology, College of Stomatology, Xi'an Jiaotong University, Xi'an, Shaanxi, China; Department of Cariology and Endodontics, Xi'an Jiaotong University, Xi'an, Shaanxi, China.
Introduction And Aims:
The aim of this study was to determine if Dynamin-related protein 1 (Drp1) -dependent mitochondrial fission is involved in the pathological process of apical periodontitis and elucidate the underlying mechanisms.
Methods:
Immunohistochemistry, immunofluorescence, and western blotting assessed CD86 expression, NLRP3/Caspase1/IL-1β activation, and mitochondrial dynamics-related proteins in human periapical macrophages. In vitro apical periodontitis (AP) models used macrophages stimulated with P. gingivalis LPS (Pg-LPS), pretreated with/without Drp1 inhibitor Mdivi-1 or NLRP3 inhibitor MCC950. CD86, NLRP3/Caspase1/IL-1β, mitochondrial dynamics proteins, TNF, and IL-6 were quantified via western blot, RT-qPCR, or immunofluorescence. ROS (DCFH-DA), ATP (commercial kit), mitochondrial membrane potential (JC-1), and morphology (TEM, MitoTracker/immunofluorescence) were analysed. Multimodal approaches explored Drp1-mediated mitochondrial fission and NLRP3 inflammasome-dependent M1 polarisation. Mdivi-1-treated AP models were established to dissect Drp1's role in pathogenesis.
Results:
Our findings indicate that the Drp1-mediated excessive mitochondrial fission is present in human periapical lesions. Moreover, there was a positive correlation between the p-Drp1(Ser616) and the elevation of NLRP3, Cleaved-Caspase1, and CD86. In vitro experiments demonstrated that Mdivi-1 effectively inhibited the Pg-LPS induced abnormal mitochondrial fragmentation dependent on p-Drp1(Ser616), rescued mitochondrial dysfunction, and further suppressed the activation of NLRP3/Caspase1/IL1β and the expression of CD86. In vivo experiments showed that Mdivi-1 treatment could significantly alleviate the inflammatory bone erosion at the apex in a murine AP model by inhibiting macrophage polarisation and the NLRP3 inflammatory pathway.
Conclusion:
Drp1-mediated excessive mitochondrial fission plays a crucial role in the development of AP by promoting NLRP3 signaling pathway-dependent macrophage M1 polarisation. Targeting Drp1 may serve as a potential therapeutic strategy to prevent AP development, highlighting its clinical translational value.
Clinical Relevance:
Mdivi-1 can restore mitochondrial dynamics homeostasis in periapical macrophages, inhibit NLRP3/M1 polarisation, and reduce bone resorption. This suggests that Mdivi-1 might be a promising agent for management of AP in future.
Insights
Dynamin-related protein 1 (Drp1)-dependent mitochondrial fission drives apical periodontitis by promoting NLRP3 inflammasome activation and M1 macrophage polarization. Inhibiting Drp1 with Mdivi-1 shows therapeutic potential for managing this inflammatory bone disease.
Area of Science:
- Mitochondrial dynamics and inflammasome signaling in oral pathology.
- Cellular mechanisms of apical periodontitis pathogenesis.
- Immunomodulation of macrophage polarization in inflammatory diseases.
Background:
- Apical periodontitis (AP) involves chronic inflammation and bone destruction at the root apex.
- Macrophage polarization, particularly M1 phenotype, is critical in AP progression.
- Mitochondrial dynamics, including fission and fusion, regulate cellular inflammatory responses.
Purpose of the Study:
- To investigate the role of Dynamin-related protein 1 (Drp1)-dependent mitochondrial fission in apical periodontitis.
- To elucidate the underlying mechanisms linking Drp1, mitochondrial dysfunction, and NLRP3 inflammasome activation.
- To evaluate the therapeutic potential of targeting Drp1 in AP.
Main Methods:
- Analysis of Drp1, NLRP3 inflammasome components (NLRP3, Caspase-1, IL-1β), and M1 marker (CD86) in human periapical lesions and macrophages.
- In vitro AP models using P. gingivalis LPS-stimulated macrophages treated with Drp1 inhibitor (Mdivi-1) or NLRP3 inhibitor (MCC950).
- Assessment of mitochondrial function (ROS, ATP, membrane potential, morphology) and inflammatory markers (TNF, IL-6) using western blotting, RT-qPCR, and immunofluorescence.
Main Results:
- Elevated Drp1-mediated mitochondrial fission and p-Drp1(Ser616) levels correlated with increased NLRP3, Cleaved-Caspase-1, and CD86 in human AP lesions.
- Mdivi-1 treatment inhibited Drp1-dependent mitochondrial fragmentation, restored mitochondrial function, and suppressed NLRP3/Caspase-1/IL-1β activation and CD86 expression in vitro.
- In vivo Mdivi-1 administration reduced inflammatory bone erosion in a murine AP model by inhibiting macrophage M1 polarization and the NLRP3 pathway.
Conclusions:
- Drp1-mediated excessive mitochondrial fission is a key driver of apical periodontitis by promoting NLRP3 inflammasome-dependent M1 macrophage polarization.
- Targeting Drp1 with inhibitors like Mdivi-1 offers a potential therapeutic strategy for AP, restoring mitochondrial homeostasis and reducing inflammation.
- Mdivi-1 demonstrates clinical translational value for managing AP by inhibiting M1 polarization and mitigating bone resorption.
