Establishiment Of Orthodontic Ligature Model Of Mouse Periodontitis And Microbial Diversity Study In The Prosess Of Periodontitis

ObjectivePeriodontitis(PD)is a common chronic periodontal disease caused by the interaction between microorganisms in dental plaque and the host immune response,and is the major cause of the dental supporting tissue destruction and tooth loss.Experimental PD is recognized as a suitable model to explore mechanisms of pathogenesis and the therapeutic methods of periodontitis.Silk ligature-induced PD is the best suitable PD model due to the small size of the murine oral cavity and teeth although is technically difficult to perform.Therefore,a simplified and effective orthodontic wire ligature method was developed to generate the experimental murine PD model in the current study.MethodOrthodontic wire rings were inserted between the first and second molars of mice for 18 days and provided a simplified and effective method for the establishment of a PD mouse model.Osteoclast activation,alveolar bone loss and periodontal inflammation were analyzed by micro-CT,histological staining and q PCR.In addition,pyrosequencing of16 S rRNA gene amplicon was used to analysis the development of oral microorganism dysbiosis in the mice.ResultsA new and effective mouse PD model was established by orthodontic wire insertion.Micro-CT and TRAP staining showed that the orthodontic wire ligature treatment led to the progressive loss of alveolar bone and osteoclast activation in alveolar bone.The results of H&E staining and q PCR showed that the infiltration of inflammatory cells was significantly increased and the expression levels of inflammatory genes IL-1β and IL-6 were up-regulated in the gingival tissues of ligature-induced PD mice.In addition,the aerobic and anaerobic bacterial loads in the oral cavity of orthodontic ligature mice increased significantly.Pyrosequencing of 16 S rRNA gene amplicons revealed that the α diversity of the oral microbiota in the orthodontic ligature group was not changed and the composition of oral microbiota presented a transition at the phylum level as the disease progressed.Abundance of Proteobacteria and Fusobacteria increased while Firmicutes and Actinobacterium decreased in the ligature model.At the genus level,the relative abundance of Rodentibacter and Neisseria increased while Muribacter,Streptococcus,Rhodococcus,Bacillus and Staphylococcus decreased.PCA and PCo A analysis showed that there were significant differences in oral microbiota communities between orthodontic ligature mice and healthy controls.However,the above changes in Porphyromonas gingivalis(PG)infection group and LPS groups derived from PG(PG-LPS)were not as obvious as orthodontic wire ligature group.ConclusionOrthodontic wire ligature can lead to osteoclast activation,alveolar bone loss,periodontal inflammatory cell infiltration and up-regulated expression of inflammatory factors.We therefore successfully established a novel and simplified mouse PD model.The effects were superior to the PG and PG-LPS models and the new orthodontic wire treatment resulted in oral microbial community transitions that mimicked polymicrobial communities characterized by polymicrobial synergy and dysbiosis.These factors all contribute to PD development.Therefore,our model is suitable for further study of PD pathogenesis and exploring treatment strategies for PD.