Abstract: Objective: To investigate the correlation between M1 macrophages and osteoclastogenesis in periodontitis. Methods: Periodontitis model was established of the right maxillary on 2-month-old C57BL/6J mice, with left maxilla as control. Mice were sacrificed 7 days after surgery. Micro-CT was used to detect alveolar bone loss and histological staining was conducted to examine M1 macrophages and osteoclasts. The expression of genes related to M1 macrophages and osteoclastogenesis was detected by real-time RT-PCR. The correlation between numbers of M1 macrophages and osteoclasts, and location relation of them were analyzed. Results:? Mouse periodontitis model was established successfully. Micro-CT results showed significant decrease of bone volume, BV/TV, Tb.N, Tb.Th and BMD of alveolar bone in right maxilla with periodontitis (P<0.05). And histological staining showed that number of M1 macrophages and osteoclasts significantly increased in maxilla with periodontitis (P<0.05). Expressions of M1 macrophages related genes (Il-1β, Il-6, Tnf-α, iNos), and osteoclastogenesis genes (Oscar, Mmp9, Ctsk, Trap) significantly elevated in periodontitis (P<0.05). Correlation analysis results indicated positive correlation between M1 macrophages and osteoclastogenesis in periodontitis. Co-staining results showed that osteoclast mainly located on alveolar bone surface with M1 macrophages around. Conclusions: In periodontitis, M1 macrophages and osteoclasts were increased and there was positive correlation between them, and there were many M1 macrophages around the alveolar bone surface where osteoclasts located.

Key words: periodontitis, M1 macrophages, osteoclast, alveolar bone resorption