miR-375调控TSLP-JAK信号轴介导循环纤维细胞骨架重构在哮喘气道重塑中的作用

Clinical trials of therapeutic intervention to prevent asthmatic airway remodeling are currently lacking. Since airway remodeling in asthmatics can ultimately lead victims to death, to explore the mechanisms underlying its pathogenesis admits of no delay. The most important pathologic feature of airway structural alterations in severe asthmatics is circulating fibrocytes's migration and recruitment in airway. Recruitment of circulating fibrocytes from the peripheral circulation to the airway tissues and its transdifferentiation into myofibroblasts are crucial in asthmatic airway remodeling process. In this context, it is necessary to expound the mechanism how environmental damage factors to initiate and mediate the migration of circulating fibrocytes to airway tissues. We have demonstrated that upregulated TSLP, an epithelium-derived cytokine, resulted in airway remodeling of asthmatic mice (PLoS One. 2013:e51268.). However, the questions that, what is the upstream regulator of TSLP and what is the downstream effector cell of TSLP, are still unclear. The ideas of this study come from our preliminary experiments and the roles that TSLP played in atopic dermatitis and mesenchymal stem cells. In the present project, in vivo and in vitro models will be designed to test our hypothesis, and reveal how damage signals from epithelial cells to upregulate TSLP expression by miR-375, then activate JAK/STAT pathway in circulating fibrocytes, mediate cells skeleton structure reconsititution, drive circulating fibrocytes to immigrate in and participate in airway remodeling process. The development of this project will provide a new insight between cells movement and pathogensis of asthmatic airway remodeling, and could significantly contribute to investigate potential targets and strategies for clinical interventions of asthmatic airway remodeling, which may consequently improve the treatment for chronic asthma.

气道重塑是哮喘治疗的难点，可导致患者死亡，探明其发病机制刻不容缓，而循环纤维细胞（CF）在气道组织浸润、转分化为肌成纤维细胞是其突出的病理特征。因此，揭开CF自外周循环迁移入气道组织的分子机制至关重要。我们已证实，气道上皮细胞损伤后，分泌的胸腺基质淋巴细胞生成素（TSLP）是启动和维持气道重塑关键的因子（PLoS One.e51268,2013）。但是TSLP上游的调控信号是什么？TSLP又通过哪个下游信号通路激活效应细胞？受课题预实验和TSLP在异位性皮炎、间充质干细胞方面研究成果的启发，我们拟通过体内外实验，验证外界环境损伤因子通过内源性信号miR-375上调TSLP过表达，进而激活JAK/STAT通路，引起CF骨架重构，使其由外周迁移到气道并在组织浸润，参与气道重塑的创新性假设。课题设计开拓了从细胞运动的角度探索气道重塑发病机制的新思路，预期结果有望为突破哮喘治疗的瓶颈提供干预靶点。

哮喘的最终病理改变为慢性气道炎症诱发的气道重塑，严重影响患者肺功能及生命质量，甚至可以引起死亡，但其机制尚不清楚。前期研究表明TSLP是气道重塑的始动因子，而纤维细胞则参与气道重塑，但纤维细胞参与气道重塑的机制尚未明确。本课题通过建立慢性哮喘小鼠模型，发现TSLP诱导肌成纤维细胞、纤维细胞在气道局部的聚集、浸润，并诱发气道局部炎症反应，从而引起气道内炎症细胞浸润、气道管壁周围胶原沉积、气道黏液腺增生及气道上皮下纤维化，最终引起哮喘气道重塑，为探讨纤维细胞引起哮喘气道重塑的机制奠定了基础。与此同时，本课题组还发现TSLP与变应性鼻炎-哮喘综合征模型（CARAS）小鼠的鼻敏感症状也有关，而且诱发了鼻粘膜结构改变与肺内炎症反应，而鼻内局部应用CpG-ODN能有效抑制TSLP过表达和气道内炎症反应。TLR4特异性抑制剂TAK242也能降低TSLP的生成，从而抑制气道内Th2型气道炎症反应，继而抑制哮喘气道重塑。细胞和动物实验也表明，IL-37能通过NF-κB和ERK 1/2通路抑制TSLP生成，从而抑制哮喘气道重塑。哮喘的急性发作与Th17/Treg失衡，而非Th1/Th2炎症反应失衡有关。这些发现都为哮喘的发病机制提供了新的线索，也为临床治疗提供了新的思路。项目资助发表SCI论文5篇，核心论文1篇。培养博士生研究生2名，硕士研究生3名，均已获得学位，项目投入经费75万元，支出46.4394万元，各项支出与预算基本相符。剩余经费28.5605万元，计划用于本项目相关研究后续支出。