PI3K/Akt/mTOR-自噬在牙周炎骨吸收中的作用及机制研究

Periodontitis-related alveolar bone resorption is closely related with osteoclast. Recent studies indicated that autophagy is involved in the regulation of the differentiation of osteoclasts under stress. Thus，we speculated that autophagy may also play a role in periodontitis-related alveolar bone resorption and osteoclast-mediated bone resorption process. PI3K/Akt/mTOR is one of the important signal transduction pathways which regulated autophagy. We have found that the phosphorylation of mTOR was decreased ,and the expression of autophagy-related protein in macrophage was increased after stimulation of Porphyromonas gingivalis lipopolysaccharide (Pg LPS). Therefore in the project,we intend to establish the mice model of periodontitis in vivo and use Pg LPS to stimulated the RAW264.7 cells in vitro. The immunohistochemistry, Real-time PCR, Western blot, RNA interference and other techniques are intends to be used to examine the underlying molecular mechanisms. The project intends to provide an integrated research from the molecular, cellular, and the overall level in order to elaborate the mechanism of the the pathophysiology of periodontitis and further find new ideas and approach of periodontitis treatment.

牙周炎相关的牙槽骨吸收与破骨细胞增强密切相关。近来研究表明自噬参与调控了应激下破骨细胞的分化。我们猜测自噬可能也参与了牙周炎相关的牙槽骨吸收以及破骨细胞介导的骨吸收的过程。PI3K/Akt/mTOR是调节细胞自噬的重要信号转导通路。课题组前期已发现牙龈卟啉单胞菌脂多糖（Pg LPS）刺激后，巨噬细胞中mTOR磷酸化下调，而自噬相关蛋白表达增加。因此本课题拟采用免疫组化、Real-time PCR、Western blot和RNA干扰等多种手段，通过Pg LPS诱导的小鼠牙周炎模型及Pg LPS刺激的RAW264.7细胞，探讨PI3K/Akt/mTOR信号通路以及自噬对牙周炎牙槽骨吸收的影响。本课题从分子、细胞和整体水平上开展整合性研究，以期深化对牙周炎的病理生理机制的理解，为其治疗开辟新思路和新途径。

牙周炎是发生在牙齿支持组织的感染性炎症性疾病。是一种世界范围内的口腔高发疾病，严重影响人类生活质量。牙周炎的一个主要表现之一是牙槽骨的吸收。而自噬是在真核细胞中广泛存在的一种细胞生存和自稳的机制。.我们的研究表明：自噬参与了牙周炎中牙槽骨吸收的发生发展。本课题在体外，使用革兰氏阴性杆菌细胞壁的主要组分之一脂多糖(Lipopolysaccharides, LPS)模拟口腔炎症微环境，结合自噬的抑制剂3-Methyladenine (3-MA)、氯喹(Chloroquine, CQ)，对人工培养的小鼠骨髓来源的巨噬细胞（bone marrow-derived macrophages, BMM）进行刺激，研究破骨细胞的分化以及自噬的发生行为；在体内，采用大鼠的牙周结扎模型，对3-MA、CQ对牙槽骨吸收情况的改变及自噬水平的表达变化进行研究。结果表明；LPS在体外对向破骨细胞的分化具有促进作用，促进了自噬的发生。而抑制自噬可以抑制小鼠骨髓来源的巨噬细胞向破骨细胞的分化。在体内模型中，牙周炎促进了自噬的发生，而高浓度的自噬抑制剂3MA可以抑制牙周炎过程中的骨吸收。.综上所述，本实验结果提示抑制PI3K/AKT信号通路及自噬水平，能够部分程度降低牙周炎所造成的实验动物的牙槽骨吸收这将为牙周炎的治疗提供一种新思路。