牙龈卟啉单胞菌感染的牙周膜细胞源性外泌体/exosomal miR-144-3p在牙周炎病理性骨改建中的作用及机制研究

外泌体是细胞产生的含有蛋白、核酸等分子并可将其靶向转移至受体细胞的微囊泡。微生物感染可改变外泌体内含物的组份，从而影响受体细胞的表型和功能。我们发现，P.g感染的牙周膜细胞产生的外泌体能明显抑制牙周膜细胞的矿化。测序结果显示，该外泌体中miR-144-3p显著升高；体外实验中，miR-144-3p的类似物可抑制成骨前体细胞分化，但可促进破骨前体细胞分化。软件预测和文献报道，miR-144-3p的多个靶基因都与骨改建相关，且在不同的细胞中其通过调控不同的靶基因参与骨改建。因此我们推测，P.g可通过被感染细胞产生的外泌体miR-144-3p作用成骨和破骨细胞，破坏骨稳态，促进骨吸收。本项目以P.g感染的牙周膜细胞源性外泌体miR-144-3p对牙周炎病理性骨改建的调控作用和机制为切入点，率先提出微生物可通过受感细胞外泌体调控牙周炎进展，研究结果将为阐明牙周炎病理机制及探索有效治疗方案提供新思路

Exosomes are a class of extracellular vesicles released by all cells, with a size range of 30–150 nm and a lipid bilayer membrane. Exosomes contain DNA, RNA, and proteins. Critically, the discovery that exosome contents can be transferred to a recipient cell via fusion to mediate phenotypic alterations supports the notion that exosomes are dynamic mediators of intercellular communication。During the course of infection, exosomes can convey pathogen molecules that serve as antigens or agonists of innate immune receptors to induce host defense and immunity, or serves as regulators of development, signal transduction and cell survival of recipient cells. These molecules may include proteins, nucleic acids, lipids, and carbohydrates. Emerging evidence indicates that exosomal miRNA play an important role in the bone remodling. In previously study, we found exosomes derived from P. gingivalis infected periodontal ligament cells can inhibit the mineralization of periodontal ligament cells. The analysis of second-generation sequencing results showed that these exosomes are rich in miR-144-3p. While some predicted target genes of miR-144-3p are correlated with bone homeostasis. And the miR-144-3p mimics can inhibit the mineralization of osteoblast progenitor cells, MC3T3-E1and promote the differentiation of osteoclast progenitor cells, RAW264.7, in vitro. According to the literatures and our results previously, we hypothesis: P.gingivalis infected periodontal ligament cells derived exosomal miR-144-3p can reduce alveolar bone formation and promote bone absorption. In this project, miR-144-3p knockdown and over expression cell models and miR-144-3p knockdown mouse model will be used to investagate the role of P. gingivalis infected periodontal ligament cells derived exosomal miR-144-3p in pathological alveolar bone remodeling, and the mechanisms will be studied as well. The results of this project will broaden our understanding of the pathogenesis of periodontitis and the possibility of using exosomes as promising candidates of therapeutic targets or drug delivery vehicles for therapy of periodontitis.