B10 cell-induced PD-L1/PD-1-linked macrophage polarization in periodontitis.

Background and Objectives: Periodontitis is a chronic multifactorial inflammatory disease caused by the excessive host immune response to bacterial infection, leading to periodontal tissue destruction. Owing to their plasticity, macrophages are key players in this process, and B10 cells, with their immunosuppressive efects, are vital for periodontal immunity. We propose that, in periodontitis, B10 cells transmit immunosuppressive signals Methods: B10 cells were cocultured with RAW264.7 cells in the presence or absence of a Transwell insert. The M2 macrophage proportion and PD-1 expression in macrophages were assessed by flow cytometry and quantitative polymerase chain reaction (qPCR). PD-L1 knockout (KO) B10 cells and wild-type B10 cells were subsequently cocultured with macrophages separately. For Results: Compared with the indirect coculture, the direct coculture of macrophages with B10 cells led to a greater proportion of M2 macrophages and increased PD-1 expression levels in macrophages. Coculturing macrophages with PD-L1 KO B10 cells confirmed that B10 cells induced the M2 polarization of macrophages and upregulated PD-L1 expression in macrophages Conclusion: B10 cells can regulate macrophage polarization