小胶质细胞活化在椎间盘退变引起腰痛中的作用和分子调控机制

The time-point prevalence rate of low back pain is as high as 26% in Chinese adults. Common back pain substantially impairs patients’ quality of life and industrial production in the developing China. Although lumbar disc degeneration has long been regarded as a major cause of back pain, current understanding on neurobiology of disc degeneration induced back pain is limited. Previous studies revealed that pathological pain is closely related to microglia activation and central sensation in the dorsal horn of the spinal cord. The role of microglia activation in back pain, however, remains unclear. Our previous research observed that surgical puncture of the lumbar intervertebral disc can initiate progressive disc degeneration and induce persistent painful behaviors in mice. Moreover, a prominent microglia activation in the dorsal horn was observed, with upregulated colony stimulating factor 1 (CSF1) in the dorsal root ganglion (DRG) and its receptor CSF1R in activated microglia. Yet, the molecular mechanism underlying the link of disc degeneration and back pain remains to be explored. Based on previous findings, this project is proposed to establish a mouse model of back pain by lumbar disc puncture using a modified surgical approach and systematical behavioral assessments. This project will combine tools in pharmacology, genetics, molecular biochemistry and behavioral science to understand the roles and regulations of CSF1/CSF1R signal pathway in microglia activation in the established back pain mouse model. Further, mTOR, a potential effector in CSF1 signaling, will be specifically deleted in microglia to determine whether mTOR-mediated downstream pathway is involved in microglial activation, central sensation, and back pain. With a modified back pain animal model and a specific interest in the role of CSF1/CSF1R-mTOR pathway in microglia activation, the proposed project aims to elucidate the molecular mechanism underlying microglial activation in back pain. The study will substantially add scientific knowledge to neurobiology of back pain and findings may provide new insights for developing new clinical intervention for treating back pain.

我国成人腰痛即时患病率高达 26%，严重影响人民生活质量和经济生产。椎间盘退变是引起腰痛的重要病因，目前对其神经生物学机制认识不足。已知多种病理性疼痛与脊髓后角小胶质细胞活化和中枢敏化密切相关，但目前尚未探明小胶细胞活化在腰痛中的作用。课题组发现穿刺椎间盘可引起进行性退变，诱发小鼠出现腰痛样症状，并显著激活脊髓后角小胶质细胞；同时发现集落刺激因子1(CSF1)及其受体CSF1R在背根神经节和脊髓后角上调。基于以上发现，本项目拟改良椎间盘穿刺术建立小鼠腰痛模型，结合分子生物学、遗传学、药理学与行为学等方法系统研究CSF1/CSF1R及其下游mTOR信号通路在介导小胶细胞活化、中枢敏化及腰痛中的作用。课题从改良腰痛动物模型入手，以小胶质细胞为切入点，深入探讨CSF1/CSF1R-mTOR通路介导的小胶质细胞活化在腰痛中的作用和调控机制，旨在解析小胶质细胞活化的关键信号通路，为腰痛治疗提供新思路

源于椎间盘退变的腰痛是临床常见病，介导腰痛产生和维持的神经生物学机制尚未阐明。课题组以小鼠为实验动物，改良手术入路，构建盘源性腰痛小鼠模型，应用分子生物学、药理学和遗传学手段解析椎间盘退变后脊髓后角小胶质细胞激活的作用及分子机制，取得了以下科研成果：1）改良的腰椎间盘穿刺术创伤小，操作简便，可快速诱发椎间盘退变和腰痛样行为，是一个可靠的实验工具；2）椎间盘退变诱发脊髓后角小胶质细胞聚集和活化，并且与腰痛时相吻合，提示脊髓小胶质细胞是介导腰痛的关键细胞；3）椎间盘退变通过上调CSF1/CSF1R信号通路而激活小胶质细胞；4）利用小鼠SNI模型，发现DRG大细胞神经元和脊髓后角小胶质细胞内mTOR通路激活，上调CSF1表达，进而调控脊髓背角小胶质细胞的增殖和活化；5）条件性敲除DRG神经元而非小胶质细胞上的Mtor基因可显著缓解疼痛，提示mTOR可能是治疗疼痛的一个分子靶点。本课题首次阐明椎间盘穿刺退变后通过CSF1/CSF1R信号通路引起脊髓后角小胶质细胞的增殖和活化并诱发腰痛；mTOR信号通路介导调控脊髓小胶质细胞的活化而深度参与神经病理性疼痛的发生和维持，调控mTOR/CSF1/CSF1R通路可缓解腰痛，为临床干预疼痛提供了新的思路和科学依据。.. 课题组严格按项目计划开展实验，在全部完成项目研究内容的基础上，额外拓展神经病理性疼痛和腰椎间盘突出症下肢放射痛的神经生物学机制研究，取得了良好的科研成果。截止2021年12月，在该项目的资助下共发表SCI科技论文10篇，其中8篇第一标注本项目（81772382），2篇第二标注本项目。此外，有3篇第一标注本项目的且与疼痛分子机制相关的文章正在投稿中。课题执行4年来，培养博士研究生4名，硕士研究生1名，参加国内外学术会议13人次。同时，该项目的顺利执行为课题组进一步拓展椎间盘突出下肢放射痛奠定了坚实的基础。