TSLP-ILC2天然免疫途径活化在尘螨抗原诱发的特应性进程中的作用及机制研究

Atopic dermatitis (AD) is a common allergic skin disease, which is associated with an increased risk of developing asthma and allergic rhinitis later in life. The progression from AD to other allergic diseases was described as 'atopic march'. It has been demonstrated that the defective skin barrier function and environmental antigen sensitization via skin in early life is the important pathological linkage between AD and asthma. Recently identified cytokine thymic stromal lymphopoietin (TSLP) is a master switch of allergic inflammation, which is mainly produced by epithelial cells and keratinocytes. Some studies based on mouse models suggest that keratinocyte-produced TSLP may trigger lung inflammation and bronchial hyper-responsiveness to inhaled allergens after epicutaneous allergen sensitization. However, the potential molecular mechanism underlying the progression of the atopic march have not yet been elucidated. In our previous study, we found that mite allergen could partially activate protease activated receptor 2 in keratinocytes and induced TSLP expression through the activation of NF-κB signaling pathway. Based on the results of in vitro studies, we established dust mite allergen epicutaneous immunization induced atopic dermatitis mouse model, which produced asthma-like airway inflammation after dust mite allergen intranasal excited. The animal model completely simulates the clinical phenotype of atopic march. This project aims to clarify the molecular mechanism of TSLP elicited type-2 innate lymphoid cells responses in the progression of mite allergen induced atopic march. Elucidation of this mechanism will contribute to provide a theoretical basis for the prevention of the onset of asthma and the progression of atopic march.

特应性皮炎（AD）是常见的过敏性皮肤病并常于成年期伴发哮喘，这种过敏性疾病进程被称为特应性进程。研究表明表皮受环境抗原刺激后产生的胸腺基质淋巴生成素（TSLP）是启动特应性进程的关键分子，TSLP可能通过活化2型天然淋巴样细胞（ILC2）推动皮炎向哮喘进展，但其具体分子机制不明。本项目前期工作建立了尘螨经皮致敏、滴鼻激发诱发的"AD→哮喘"小鼠模型，并通过人体和动物研究证实尘螨抗原可刺激表皮产生TSLP从而诱发AD发病。因此本课题拟在前期研究基础上，进一步明确TSLP及其下游天然免疫途径在特应性进程中的作用和机制，在AD伴哮喘患者中探讨ILC2的作用，并以BALB/c和Rag1-/-小鼠制备的"AD→哮喘"模型为基础，从分子、细胞和整体动物水平研究"TSLP-ILC2"天然免疫途径活化在尘螨诱发的特应性进程中的作用及机制。对这一机制的阐明将有助于预防哮喘的发病及整体防控特应性疾病。

特应性皮炎是常见的过敏性皮肤病并常于成年期伴发哮喘，这种过敏性疾病进程被称为特应性进程。研究表明表皮受环境抗原刺激后产生的胸腺基质淋巴生成素（TSLP）是启动特应性进程的关键分子，TSLP可能通过活化2型天然淋巴样细胞（ILC2）推动皮炎向哮喘进展，但其具体分子机制不明。本课题通过构建抗原经皮致敏、滴鼻激发诱发的“特应性皮炎→哮喘”小鼠模型，探讨TSLP-ILC2通路活化在特应性进程中的作用和机制。通过野生型C57BL/6J小鼠构建特应性进程小鼠模型，发现小鼠皮损、肺泡灌洗液和肺组织中Th2炎症因子水平升高，嗜酸性细胞和ILC2的数量增加，通过CD90.2抗体抑制ILC2活性后，小鼠皮肤和气道的ILC2数量下降，同时皮肤和气道炎症反应程度明显减弱，嗜酸性粒细胞数量减少，这提示ILC2可参与抗原诱发的特应性进程小鼠的皮肤和气道炎症反应过程。在T/B细胞缺陷的Rag1-/-小鼠中构建特应性进程小鼠，发现抗原仍然能够诱发出皮肤和气道的炎症反应，并且嗜酸性粒细胞和ILC2细胞的数量明显增加，提示在没有适应性免疫的情况下，ILC2参与特应性进程小鼠皮肤和气道的炎症反应过程。在抗原诱导的特应性进程小鼠中，通过涂抹MC903促进表皮高表达TSLP，发现小鼠皮肤和气道的炎症反应显著增强，肺组织中的嗜酸性粒细胞和ILC2数量也显著增加，说明皮肤TSLP的高表达可以促进ILC2数量的增多，并进而加强特应性进程中皮肤和肺组织的炎症反应。总之我们的研究结果说明“TSLP–ILC2”这一天然免疫途径的活化在抗原诱发的特应性进程中发挥重要的作用。对这一机制的阐明将有助于了解特应性进程的发生和发展机制，并有益于预防哮喘的发病及整体防控特应性疾病。