Macrophage polarization in human gingival tissue in response to periodontal disease

OBJECTIVE: Although accumulating evidence indicates that macrophages are central players in the destructive and reparative phases of periodontal disease, their polarization states at different stages of periodontal inflammation remain unclear. METHODS: We collected gingival biopsies from patients with chronic periodontitis (P group), gingivitis (G group), or periodontally healthy individuals (H group). Polarized macrophages were identified through immunofluorescence. M1- and M2-related cytokines were detected by immunohistochemistry. RESULTS: Compared with the H group, the P group had more M1 cells (higher M1/M2 ratio) and significantly higher TNF-α, IFN-γ, IL-6, and IL-12 levels. Although the G group also exhibited higher TNF-α and IL-12 levels than the H group, they had similar M1/M2 ratios. The M1/M2 ratio and IFN-γ and IL-6 levels were significantly higher in the P than the G group. Among M2-related cytokines, IL-4 levels were significantly higher in the G than the H group. The M1/M2 ratio was positively correlated with clinical probing depth (PD), and both were positively correlated with IFN-γ and IL-6. PD was negatively correlated with IL-4. CONCLUSION: Macrophage polarization in gingival tissue may be responsible for the development and progression of inflammation-induced tissue destruction, and modulating macrophage function may be a potential strategy for periodontal disease management.