HMGB1/RAGE信号调控Th17/IL-17及其在气道上皮-间质转化与哮喘气道重塑中的作用研究

Airway remodeling is one of the reasons for why asthma shows steroid-resistant, in which epithelial-mesenchymal transition (EMT) in the airway plays an important role. Recent study found that there was abnormal expression of HMGB1/RAGE signal in asthmatics, but its function and mechanism is still unclear. Th17/IL-17 plays a key role in the airway remodeling of asthma, and some data have confirmed that HMGB1 could promote the proliferation and activation of Th17 in vitro. We have found that IL-17 could enhance bronchial EMT in vitro; moreover, our preliminary experiment suggested HMGB1 also could promote EMT similar to IL-17, and showed a synergistic effect when together with IL-17. So in this study, airway epithelium will be used to induce cell model of EMT, and meanwhile, wild-type and RAGE-/- mouse will be administrated to establish animal models of airway remodeling, which act as carriers for this study.And then Th17 development in vitro with adoptive transfer in vivo, HMGB1, IL-17 and their respective neutralizing antibody will be performed through intraperitoneal injection. Based on the above, we will first investigate the effect of HMGB1/RAGE signaling on regulating Th17/IL-17 and its role in the airway EMT and airway remodeling of asthma, and meanwhile, we will also analyze whether blockade of HMGB1 signaling could improve the degree of steroid-resistance, which would provide theory basis to elucidate the pathogenesis of asthma and to explore new targets for the prevention and treatment of steroid-resistant asthma.

气道重塑是哮喘产生激素抵抗的原因之一，而气道发生上皮-间质转化（EMT）在其中起重要作用。近来研究发现哮喘患者存在着HMGB1/RAGE信号的异常表达，但其作用与机制不清楚。已知Th17/IL-17在哮喘气道重塑过程中发挥重要作用，并有体外研究证实HMGB1可促进Th17的增殖活化。我们的前期研究发现IL-17可增强气道上皮-间质转化过程；预实验还发现HMGB1也呈相似作用，并与IL-17具协同效应。故本研究拟以气道上皮诱导建立EMT细胞模型及RAGE-/-等小鼠诱导建立气道重塑动物模型为研究载体，利用Th17体外分化行体内过继回输、HMGB1与IL-17及其中和性抗体行腹腔注射等手段，首次探讨HMGB1/RAGE信号调控Th17/IL-17及其在哮喘气道EMT与气道重塑中的作用；同时观察阻断HMGB1信号能否改善激素抵抗，为阐明哮喘发病机制及发掘激素抵抗型哮喘防治新靶点提供理论基础。

气道上皮-间质转化（EMT）在气道重塑及难治性哮喘发生中起重要作用。前期研究发现哮喘患者存在着HMGB1信号的异常表达，但其作用与机制不清楚。我们的前期研究发现IL-17可增强气道上皮-间质转化过程；预实验也发现HMGB1也呈相似作用，并与IL-17具协同效应。本研究拟探讨HMGB1信号调控CD4+T细胞亚群Th17/IL-17及其在哮喘气道EMT与气道重塑中的作用，为阐明哮喘发病机制及发掘难治性哮喘防治新靶点提供理论基础。遵照研究计划陆续完成体内、外实验，取得了重要研究进展并初步证明了：（1）HMGB1/RAGE信号可以调控诱导Th17细胞的分化成熟及其功能表达，并提高IL-17细胞的分泌水平。同时，也观察了HMGB1信号可优势诱导Th2型免疫应答，参与经典的Th1/Th2免疫平衡调控；（2）HMGB1/RAGE信号可以促进气道上皮细胞发生上皮-间质转化过程；而通过提高Smad3的磷酸化水平可能在促进TGF-β1诱导的支气管上皮细胞的EMT发生过程其重要作用。（3）Th17/IL-17信号可以协同增强HMGB1/RAGE信号调控并促进气道上皮-间质转化的过程。（4）动物在体实验进一步证实了HMGB1信号参与哮喘发病，而且可能通过增强诱导气道局部Th2型应答而加重哮喘气道炎症反应，而Th17/IL-17信号可能在HMGB1信号诱导哮喘气道重塑过程发挥作用。基于以上研究结果，本课题明确了HMGB1信号参与哮喘的发病过程，并优势诱导过敏性哮喘气道炎症；全面分析了HMGB1信号可调控CD4+T细胞亚群分化与功能表达，即HMGB1/RAGE信号可以调控诱导Th17细胞的分化成熟及其功能表达，并提高IL-17细胞的分泌水平；同时，HMGB1信号还可诱导Th2型免疫应答，参与经典的Th1/Th2免疫平衡调控过敏性气道炎症；此外，HMGB1信号可促进气道上皮细胞发生EMT，并可能在哮喘气道重塑中发挥作用，而Th17/IL-17信号在其效应过程中呈现协调增强效应，这可能是激素抵抗及难治性哮喘发生的机制之一，这也为进一步阐明哮喘气道重塑发生机制及寻求改善难治性哮喘临床诊疗困境手段提供了初步的理论依据。