BMMSCs通过上调肺内树突状细胞Tyro3的表达改善哮喘的机制研究

Asthma is one of the most common chronic respiratory diseases, mostly driven by dendritic cells(DCs) induced Th2 immune response. Bone marrow derived stem cells(BMMSCs) can alleviate Th2 immune inflammation in asthma models, while its mechanism is still ambiguous. our previous study shows that BMMSCs can inhibit the surface co-stimulating molecular and functions of lung DCs in asthma mice. Further study indicated that Tyro3 can inhibit the activation of DCs, then terminate the Th2 immune response. And our pre-experimental results indicated that BMMSCs can promote the lung DCs to express more Tyro3 in asthma models. What’s interesting, Tyro3 expression in asthma patients’ plasma showed obviously less than that in healthy controls. All these results indicated that Tyro3 may play a significant role in BMMSCs regulating DCs functions. Based on this hypothesis，we will design the following experiments centered on Tyro3 at the molecular level to reveal the regulating signal pathway in which BMMSCs upregulation the Tyro3 expression and to explored the regulation mechanism of Tyro3 on DCs function. The co-culture system of BMMSCs/DCs will be constructed at the cellular level, and the interaction model will be studied by interfering with Tyro3 expression. At the same time, the asthma model of Tyro3 knockout mouse was constructed to validate the hypothesis that BMMSCs inhibit the Th2 inflammatory response in asthma through regulating the expression of Tyro3 in DCs. By these, we hope to provide new evidence for the treatment of asthma by BMMSCs and new ideas for targeted therapy of asthma.

骨髓间充质干细胞（BMMSCs）可改善哮喘动物模型Th2型炎症反应，但其机制不明。申请人前期研究发现BMMSCs可抑制哮喘小鼠肺内树突状细胞（DCs）活化及抗原呈递功能。预实验结果显示BMMSCs能显著促进哮喘小鼠肺DCs中Tyro3的表达，且哮喘患者外周血浆表达Tyro3较健康人低。这些结果提示Tyro3可能作为BMMSCs负调DCs功能的关键信号分子。据此，本课题拟以Tyro3为中心，在分子水平深入揭示BMMSCs调控Tyro3表达的信号通路，探索Tyro3对DCs功能的调节机制；在细胞水平构建BMMSCs/DCs共培养体系，并通过干预Tyro3表达，研究其相互作用模式；同时构建Tyro3敲除小鼠哮喘模型，在体验证BMMSCs通过调控DCs表达Tyro3、进而抑制哮喘Th2型炎症反应这一假说。以期为BMMSCs治疗哮喘提供新的证据，为哮喘治疗提供新的靶点。

树突状细胞（DCs）作为天然免疫和适应性免疫反应的桥梁，在支气管哮喘的发生发展过程中起着关键作用。有效抑制肺组织DCs募集及功能有望突破目前哮喘治疗的瓶颈。本项目研究在前期发现BMMSCs改善哮喘基础上，通过实验发现BMMSCs通过抑制肺内DCs及Th2反应进而改善哮喘病情，且BMMSC改善哮喘小鼠病情的同时肺组织DCs表达Tyro3明显增加。哮喘急性发作患者外周血Tyro3表达水平较健康对照组均明显下降。我们进一步利用腺病毒转染敲低小鼠Tyro3表达水平，通过小鼠模型实验、体外细胞实验等手段探究Tyro3在哮喘发生中的作用。我们发现哮喘小鼠肺组织中及肺内树突状细胞表达Tyro3明显下降，敲低Tyro3后哮喘反应进一步加重。BMMSCs可明显改善哮喘反应，且肺组织中树突状细胞表达Tyro3明显增高；敲低Tyro3后，BMMSCs改善哮喘Th2反应作用减弱。最后得出结论：BMMSCs通过上调肺组织中的树突状细胞表达Tyro3从而改善哮喘，为揭示BMMSCs和DCs在哮喘治疗中发挥的作用提供依据，为哮喘的靶向治疗提供新的思路。