Induction of B10 function on ligature-induced experimental periodontitis

Abstract Objective IL-10 producing B cells (B10 cells) play an essential role in immune system balance by suppressing excessive inflammatory responses. This study is to investigate induction of B10 function in vitro and their effect on ligature-induced experimental periodontitis in vivo. Methods Spleen B cells were isolated from C57BL/6J mice and cultured for 48 hours under the following conditions: control, CD40L (1 μg/ml), IL21 (25, 50, 100, 1000ng/ml), anti-Tim1 (2.5, 5, 10, 20 μg/ml), CD40L + IL21, CD40L + anti-Tim1, CD40L + IL21 + anti-Tim1. The mRNA level and secreted protein level of IL-10 expression were detected by RT-qPCR and ELISA respectively. Silk ligatures were tied around both maxillary second molars of C57BL/6J mice for two weeks. Optimized combination of CD40L, IL21 and anti-Tim1 and vehicle were injected into contralateral side of palatal gingiva on days 3, 6 and 9. The palatal gingival tissues and maxillary bone were collected on day 14 to determine expressions of IL10 and RANKL and periodontal bone resorption respectively. Results IL-10 expressions of cultured spleen B cells were significantly increased in the presence of CD40L, IL21 and anti-Tim1 combination when compared with control groups. Gingival IL-10 expression were significantly increased after injection of CD40L, IL21 and anti-Tim1 combination, when compared to the control side (p<0.05). The gingival RANKL expression and periodontal bone loss were significantly decreased on the side with combined injection of CD40L, IL21 and anti-Tim1, as compared to the control side (p<0.05). Conclusion CD40L, IL21 and anti-Tim1 combination induced IL-10 production by B cells and inhibited periodontal bone loss in ligature-induced experimental periodontitis.