Local promotion of B10 function alleviates experimental periodontitis bone loss through antagonizing RANKL-expressing neutrophils.

Abstract

Persistent host immune responses initiated by oral bacteria protect host against infection but may also elicit the process of sustained periodontal inflammation and subsequent alveolar bone loss. Interleukin-10 (IL-10), an anti-inflammatory cytokine, can downregulate pro-inflammatory cytokine and inhibit neutrophil migration in inflammation. IL-10-expressing regulatory B cells (B10) is termed by negatively regulating immune response through IL-10 and are mainly restricted in CD19+ CD1dhi CD5+ B cells in mice. Our current study was aimed to explore the effect of locally transferred CD19+ CD1dhi CD5+ B cells on inflammation and alveolar bone loss in an experimental periodontitis mouse model. Ligation plus P. gingivalis (Pg) infection was used to induce periodontitis in a mouse model. CD19+ CD1dhi CD5+ B cells were sorted by flow cytometry and transferred into the gingivae immediately on the fifth day after ligation. All the mice were sacrificed on day 14 after ligation. H&E staining showed that inflammatory cell infiltration was significantly reduced by the CD19+ CD1dhi CD5+ B cells. Toluidine blue staining showed that the CD19+ CD1dhi CD5+ B cells alleviated alveolar bone loss in the ligature/Pg-induced periodontitis in mice. Immunohistochemical staining showed Receptor Activator of NF-KappaB Ligand (RANKL), Interleukin-1β(IL-1β) and Interleukin-17 (IL-17) were decreased after the CD19+ CD1dhi CD5+ B cell transfer. Immunofluorescent staining showed that IL-10 was increased while the number of Ly6G+ neutrophil and its RANKL production were decreased in gingival tissue. These results indicated that locally transferred CD19+ CD1dhi CD5+ B cells may alleviate alveolar bone loss through inhibiting pro-inflammatory cytokine expression and RANKL-expressing neutrophils in the periodontitis mouse model.