CystatinF介导骨髓源性细胞对Aβ清除作用机制及改善阿尔茨海默病转基因小鼠认知功能障碍的研究

Beta-amyloid (Aβ) is the core of the pathogenic substances, and it is also the most important target of prevention and treatment of AD. Our previous study showed that, the expression of cystatin F in AD monocytes was increased. Cystatin F could promote the degradation of Aβ in monocytes. The learning and memory ability of cystatin F+/APP+ hybridized mouse have been improved obviously. We speculate that the increased of cystatin F expression is a response to Aβ stimulation and has Aβ-dependent. It is a protective mechanism for AD. In this project, we will further analysis the expression of cystatin F in different stages of AD monocytes, and the relationship between cystatin F and the Aβ level in plasma; explore the molecular mechanism of degradation of Aβ mediated by cystatin F in monocytes; explore the molecular mechanism of improvement of cognitive dysfunction mediated by cystatin F in AD model mouse; analysis the improvement of cognitive dysfunction of AD model mouse that received the bone marrow transplantation modified by cystatin F. This project is expected to explain the molecular mechanism of the clearance of Aβ in bone marrow derived cells and the improvement of cognitive dysfunction in AD model mouse mediated by cystatin F. The project presents important information that could lead to the development of a new and effective therapy for the treatment of AD.

β淀粉样蛋白（Aβ）是阿尔茨海默病（AD）的核心致病物质，也是AD防治最为重要的靶点。我们前期发现：Cystatin F在 AD单核细胞中表达增高；cystatin F促进单核细胞降解Aβ；Cystatin F+/ APP+小鼠空间探索和学习记忆能力提高显著。我们推测，Cystatin F在单核细胞中可能是Aβ依赖的反应性升高，是AD发病时的一种保护性机制。本项目将进一步分析Cystatin F在不同阶段AD单核细胞中的表达及与血中Aβ水平的关系；探讨Cystatin F促进单核细胞降解Aβ的分子机制；探讨Cystatin F改善AD小鼠认知功能障碍的机制；对AD小鼠进行骨髓移植，分析经Cystatin F修饰后的骨髓细胞对AD小鼠认知功能障碍的改善。本项目的完成可望阐明Cystatin F促进骨髓源性细胞清除Aβ和改善AD小鼠认知功能障碍的分子机制，为AD防治策略的研究提供新的科学思路。

阿尔茨海默病（AD）是严重危害人类健康的神经退行性疾病。了解其发病的分子机制和寻找有效的治疗方法对AD的防治具有重要的意义。在本项目中，（1）我们发现AD患者血浆中cystatin F的分泌量较同龄对照组略有升高，但是Aβ表达未见发生改变。这提示，cystatin F主要在AD脑内影响Aβ代谢，cystatin F是将AD外周固有性免疫和脑内关联的一个关键性分子；（2）我们在体外成功地鉴定了cystatin F能够与Aβ直接结合，该结果提示，cystatin F可作为一个潜在的靶点，直接参与Aβ清除。该部分结果阐明了cystatin F介导骨髓源性细胞清除Aβ的分子机制，为AD发病机制补充新的科学资料；（3）构建Cystatin F-apoB的慢病毒表达质粒，将慢病毒注射到AD小鼠体内，结果发现Cystatin F-apoB慢病毒颗粒组脑内Aβ斑块明显减少。这说明，Cystatin F通过apoB载体进入脑内后，对AD的斑块起到了抑制作用；（4）我们利用废弃的AD受试者血浆去筛选AD诊断的标志物。利用circRNA芯片筛查到表达具有差异的circRNA共32个，其中表达上调的19个，表达下调的13个。经与AD临床的相关性分析，hsa_circ_0003391和hsa_circ_0066336与AD具有潜在相关性，血浆中hsa_circ_0003391表达下调可能是AD的潜在生物学标志物；（5）在AD血浆的血小板里，我们发现AD患者血小板脂质筏内神经节苷脂GM1含量明显高于同龄对照人群， MCI组和AD组血小板脂质筏内胆固醇水平明显升高。上述的两个分子在AD和MCI的诊断中有一定的潜在价值。综上，本项目在完成了项目书内原有的研究内容外，还开展了与AD相关的其他研究，并且获得了重要的结果。本项目推动了AD研究的进展，为AD的发病机制和治疗方向累积了一定得科学资料。