HDM通过TLR4依赖的TSLP-TSLPR信号通道触发哮喘气道重塑机制研究

Airway epithelial cells play a key role in the initiation of asthmatic airway remodeling and inflammation. Our previous studies have shown that thymic stromal lymphopoietin (TSLP) expressed in airway epithelium plays a significant part in airway inflammation of asthma, also found that TSLP was overexpressed accompanied by increased synthesis and airway deposition of early stage asthmatic airway remodeling markers including α-smooth muscle actin(α-SMA) and typeⅠcollagen. Therefore, TLSP released from airway epithelial may induce airway remodeling of asthma. According to preliminary research data, we intend to explore the mechanism of TSLP-induced airway remodeling on the basis of established the host dust mite (HDM)-triggered asthmatic mice model and culturing mice lung fibroblast cell line in vitro, through the molecular biology techniques, flow fluorescence microsphere technique, laser capture microdissection (LCM), immunohistochemistry and so on. In this study, we design to confirm the overexpression of TSLP induced by HDM binding to Toll-like receptor 4(TLR4) on airway epithelial cells, and then TSLP-TSLPR complex activated MAPKs (ERK1 / 2, P38, JNK)-STAT3 signal pathway followed by the deposition of α-SMA and typeⅠcollagen. In this study, we will clarify the mechanism of HDM-triggered asthmatic airway remodeling via the TLR4-dependent TSLP-TSLPR-MAPK-STAT3 signal pathway by taking TSLP-TSLPR signal pathway as key point. This research could pave the way for airway remodeling theoretical basis for preventing asthma patients from fixed airflow limitation, and developing the new therapeutic strategies in asthma.

气道上皮细胞在启动哮喘气道重塑和炎症中起关键作用。我们前期研究证明气道上皮释放TSLP在哮喘气道炎症中起重要作用，同时发现TSLP高表达伴随哮喘气道重塑标志物α-SMA和I型胶原气道沉积。因此，气道上皮TLSP可能诱导哮喘气道重塑。本研究根据前期研究结果，拟通过HDM诱导哮喘小鼠模型和体外培养小鼠肺成纤维细胞方法，采用分子生物学、LCM 、免疫组织化学等技术，探讨TSLP诱导哮喘气道重塑的机制，证实HDM与气道上皮TLR4结合，高表达TSLP，进而与TSLPR结合，激活MAPKs (ERK1/2、P38、JNK)-STAT3 信号通道，形成α-SMA和I型胶原沉积，最终导致气道重塑。本研究以TSLP-TSLPR信号通道为切入点，旨在阐明HDM诱导TLR4依赖的TSLP-TSLPR-MAPK-STAT3气道重塑机制，奠定哮喘气道重塑理论基础，为早期防治哮喘病人固定性气流受限提供临床治疗思路。

支气管哮喘是一种常见病和多发病，其病理特征主要为气道炎症和气道重塑。TSLP是一种气道上皮受到特应性损伤后释放的可以诱导气道炎症的关键因子。为了研究TSLP在哮喘早期气道重塑中的作用，我们探究了通过HDM 诱导肺泡巨噬细胞活化在免疫反应和气道炎症中发挥作用的机制。我们发现哮喘病人气道粘膜上皮细胞高表达TSLP、α-SMA、I型胶原蛋白，通过体内及体外实验，明确了TSLP通过TSLPR，激活MAPKs（ERK1/2、P38、JNK）-STAT3 信号通道，进而上调α-SMA 和I 型胶原表达，从而导致气道重塑。同时我们的实验也证实了MAPK抑制剂的作用，其中p38的抑制剂可以下调STAT3的磷酸化及α-SMA和Ⅰ型胶原蛋白的表达。故而我们认为TSLP在哮喘早期气道重塑中发挥重要作用。进一步的研究发现，TSLP可以通过STAT3信号通路诱导支气管上皮细胞衰老，从而引起细胞衰老相关的气道重塑。此外，我们发现IL-33 中和抗体预处理可显著降低OVA诱导的小鼠气道重塑及IL-33、α-SMA、Col1表达以及ERK1 /2及MSK1的磷酸化，从而认为IL-33可以通过ERK1 /2-MSK1信号通路促进哮喘模型小鼠气道重塑，证明了IL-33 在哮喘气道重塑中的重要作用。本项目研究从TSLP到IL-33,重点阐述了哮喘气道重塑机制中所依赖的信号通路，及气道上皮受损后释放的 TSLP、IL-33在气道炎症及气道重塑中发挥的重要作用，阻断TSLP的信号通路可减轻哮喘的气道重塑。这些理论为部分解释了哮喘气道重塑的机制，为哮喘患者的治疗开辟了新的治疗途径。