Outer Membrane Vesicles From Fusobacterium nucleatum Switch M0-Like Macrophages Toward the M1 Phenotype to Destroy Periodontal Tissues in Mice

• Published in: Frontiers in microbiology 2022-03, Vol.13, p.815638-815638
• Main Authors: Chen, Gang, Sun, Qiang, Cai, QiaoLing, Zhou, HongWei
• Format: Article
• Language: English
• Subjects: Fusobacterium nucleatum; inflammation; macrophages; Microbiology; outer membrane vesicles; periodontitis
• ISSN: 1664-302X; 1664-302X
• DOI: 10.3389/fmicb.2022.815638

Periodontitis is a chronic inflammatory oral disease that affects nearly 50% of all adults. ( ) is known to be involved in the formation and development of periodontitis. Outer membrane vesicles (OMVs) harboring toxic bacterial components are continuously released during growth and regulate the extent of the inflammatory response by controlling the functions of immune and non-immune cells in tissues. Macrophages are important immune cells in periodontal tissue that resist pathogen invasion and play an important role in the pathophysiological process of periodontitis. However, the role of the interaction between OMVs and macrophages in the occurrence and development of periodontitis has not been studied. The purpose of this study was to clarify the effect of OMVs on the polarization of macrophages and the roles of this specific polarization and OMVs in the pathophysiology of periodontitis. The periodontitis model was established by inducing ligation in C57BL/6 mice as previously described. Micro-CT, RT-qPCR, hematoxylin-eosin (H&E) and tartrate acid phosphatase (TRAP) staining assays were performed to analyze the periodontal tissue, alveolar bone loss, number of osteoclasts and expression of inflammatory factors in gingival tissue. The changes in the state and cytokine secretion of bone marrow-derived macrophages (BMDMs) stimulated by OMVs were observed by confocal microscopy, flow cytometry, Western blot and ELISA. Mouse gingival fibroblasts (MGFs) were isolated and then cocultured with macrophages. The effects of OMVs on the proliferation and apoptosis of MGFs were analyzed by flow cytometry and lactate dehydrogenase (LDH) assays. The periodontitis symptoms of mice in the OMVs + ligation group were more serious than those of mice in the simple ligation group, with more osteoclasts and more inflammatory factors (IL-1β, IL-6, and TNF-α) being observed in their gingival tissues. M0 macrophages transformed into M1 macrophages after the stimulation of BMDMs with OMVs, and the M1 macrophages then released more inflammatory cytokines. Analysis of the coculture model showed that the MGF apoptosis and LDH release in the inflammatory environment were increased by OMV treatment. In conclusion, OMVs were shown to aggravate periodontitis, alveolar bone loss and the number of osteoclasts in an animal model of periodontitis. OMVs promoted the polarization of macrophages toward the proinflammatory M1 phenotype, and the inflammatory environment further aggravated the toxi