矽肺患者及实验性矽肺中Breg诱导Treg活化、调控Th免疫应答的机制研究

Silicosis, which composed 50 percent of the pneumoconiosis, is the most severe and harmful occupational disease. The pathological change of the silicosis is the chronic lung inflammation; however, the mechanism of the immunological modulation during the pathology process is not still clearly demonstrated. Regulatory T cell (Treg) took part in regulating the inflammation development in silicosis according to our previous finding. Treg got its immunosuppression function by regulating Th immune response. Recent studies suggested that the regulatory B cell (Breg) took part in kinds of inflammatory diseases. And Breg might also play a crucial role in controlling the inflammation development, by secreting the repressive cytokine (IL-10) or inducing the Treg activation to suppress the differentiation and proliferation of effect T cell (Teff). Nevertheless, the detailed mechanism of Breg in regulating silicosis inflammation development is unclear. By observations and studies on both silicosis patients and experimental silicosis animal model, the aim of our project is to illustrate the regulatory mechanism of Breg on the activation of Treg and/or Th immune response at both cellular and molecular level. It is believed that if we demonstrated the mechanism of Breg on Treg's activation and/or Th immune response successfully, the powerful experimental and theoretical foundation will be provided to help delaying and inhibiting the development of silicosis.

矽肺患者约占我国尘肺总病例的50%，是尘肺中危害最严重的一种职业病。矽肺的病理过程主要表现为肺部慢性炎症，目前对这一病变过程的免疫调控机制尚未十分清楚。前期工作发现调节性T细胞(regulatory T cell，Treg)参与调控矽肺发生发展的病理炎症，Treg通过调控Th免疫应答发挥其免疫抑制功能。新近研究表明，调节性B细胞(regulatory B cell，Breg) 在多种炎症性疾病中发挥着重要的免疫调控作用，Breg可能通过分泌抑制性细胞因子IL-10或诱导Treg活化抑制自身效应T细胞分化及增殖，对疾病的炎症过程发挥调控作用。Breg对矽肺炎症进程的确切调控机制尚不清楚。本研究拟以矽肺患者和实验性矽肺小鼠为研究对象，从细胞、分子水平探讨在矽肺纤维化中Breg对Treg活化及Th免疫应答调控过程中相关的效应机制。旨在为延缓和阻抑矽肺纤维化提供新的实验和理论依据。

矽肺是由于生产过程中长期吸入SiO2粉尘而引起的以肺组织纤维化为主的全身性疾病。是我过职业病发病率最高危害最重的一种职业性肺疾病。仅2014年一年，我国矽肺的新发病例达11471例，约占职业病发病例总数的50%。由于矽肺不可治愈，其给整个社会带来巨大的负担。目前矽肺发病机制仍不明确，探明矽肺发病机制对矽肺患者的治疗与康复具有十分重要的现实意义。.研究显示，SiO2进入肺内首先被肺泡巨噬细胞识别，先后启动天然免疫及适应性免疫，引起肺组织炎症纤维化的一系列病理改变。前期研究提示，Th细胞在矽肺炎症纤维化发展过程中发挥重要作用，不同类型Th应答相互平衡影响了矽肺的病理进程。Treg可通过分泌抑制性细胞因子调控Th应答发挥其免疫抑制作用。其中IL-10的左右尤为突出。调节性B细胞（Breg）是一类以分泌IL-10为特征的具有调节功能的B细胞亚群。可调控多种炎症性疾病及自身免疫性疾病。但Breg在矽肺中的作用仍有待研究。.本研究通过人群血液样本分析，小鼠矽肺模型观察研究及原代细胞体外共培养检测三方面，从细胞、蛋白、基因的水平，探讨Breg在矽肺病理进程中的调控作用及分子机制。结果表明，矽肺患者外周血血清中IL-10水平及Breg数量显著升高，矽肺患者中IL-10和Breg可能通过维持调节性T细胞，抑制炎性因子，Th1型细胞因子和促进Th2型细胞因子来保持机体的免疫稳态。动物实验方面，SiO2诱导小鼠体内Breg显著增加，应用抗CD22抗体成功消除Breg。病理观察及分子生物学检测表明，消除Breg加重矽肺炎症并减轻纤维化改变。免疫学检测提示，Breg通过调节Treg影响Th免疫应答调节矽肺炎症纤维化。体外共培养分离纯化的小鼠原代B、Treg及Teff细胞，Breg不足导致其对各型Th应答的抑制能力减弱。Breg不足显著影响Treg数量、功能，同时抑制SiO2诱导型Treg的分化成熟。.综合人群、动物及细胞研究结果，本研究证实Breg在矽肺发生发展过程中发挥重要免疫调控作用。Breg通过影响Treg调节Th免疫应答进而调控矽肺的病理进程。为探索矽肺的发病机制及治疗方法提供新的理论依据。