microRNA是一段约22个核苷酸、不编码蛋白的内生性微小RNA，在多种炎症性疾病的发生发展中起着重要的调节作用。本课题组前期研究发现microRNA-155与microRNA-335-5p具有促进牙周膜细胞炎症反应的作用。本项目拟通过建立体外矿化诱导细胞模型，探讨炎症条件下microRNA-155与microRNA-335-5p在细胞成骨矿化过程中的分子调控机制及相互关系；建立大鼠根尖周炎模型，通过注射microRNA-155和（或）microRNA-335-5p的抑制剂进一步验证二者在根尖周炎中对炎症及骨代谢的作用及机制。本项目有望推动microRNA调控根尖周炎分子生物学研究的扩展深化，为根尖周炎中炎症及骨丧失的治疗提供新的理论依据。

microRNAs are small (~22nt), non-coding endogenous RNA, playing vital roles in regulating various inflammatory diseases. In our previous study, we found microRNA-155 and microRNA-335-5p played positive roles in Human Periodontal Ligament Cells (HPDLCs) inflammatory response. This study intends to explore the molecular regulation mechanism and relationship of microRNA-155 and microRNA-335-5p in osteogenesis mineralization process through establishing HPDLCs mineralizing model under inflammatory condition. To further verifying their function and mechanisms in inflammation and bone metabolism of apical periodontitis, rat model of experimental periodontitis will be established and injection of inhibitors of microRNA-155 and microRNA-335-5p will be performed. Our project will promote the research of microNRAs regulate apical periodontitis in molecular biology level, and provide new theory basis to treat inflammation and alveolar bone loss in periapical periodontitis.