B10 Cells Alleviate Periodontal Bone Loss in Experimental Periodontitis

B10 cells can regulate inflammatory responses in innate immunity. Toll-like receptors (TLRs) play an important role in B cell-mediated immune responses in periodontal disease. This study aimed to determine the effects of TLR-activated B10 cells on periodontal bone loss in experimental periodontitis. Spleen B cells isolated from C57BL/6J mice were cultured with Porphyromonas gingivalis lipopolysaccharide (LPS) and cytosine-phospho-guanine (CpG) oligodeoxynucleotides for 48 h. B10-enriched CD1d^hi CD5⁺ B cells were sorted by flow cytometry and were adoptively transferred to recipient mice through tail vein injection. At the same time, P. gingivalis-soaked ligatures were placed subgingivally around the maxillary second molars and remained there for 2 weeks before the mice were euthanized. Interleukin-10 (IL-10) production and the percentage of CD1d^hi CD5⁺ B cells were significantly increased with treatment with P. gingivalis LPS plus CpG compared to those in mice treated with P. gingivalis LPS or CpG alone. Mice with CD1d^hi CD5⁺ B cell transfer demonstrated reduced periodontal bone loss compared to the no-transfer group and the group with CD1d^lo CD5^- B cell transfer. Gingival IL-10 mRNA expression was significantly increased, whereas expressions of receptor activator of NF-κB ligand (RANKL)/osteoprotegerin (OPG), tumor necrosis factor alpha (TNF-α), and IL-1β were significantly inhibited in the CD1d^hi CD5⁺ B cell transfer group. The percentages of CD19⁺ IL-10⁺ cells, CD19⁺ CD1d^hi CD5⁺ cells, and P. gingivalis-binding CD19⁺ cells were significantly higher in recovered mononuclear cells from gingival tissues of the CD1d^hi CD5⁺ B cell transfer group than in tissues of the no-transfer group and the CD1d^lo CD5^- B cell transfer group. This study indicated that the adoptive transfer of B10 cells alleviated periodontal inflammation and bone loss in experimental periodontitis in mice.