IL-17A通过miR-200b-3p/DUSP1信号轴介导支气管哮喘糖皮质激素抵抗的机制研究

Glucocorticoid resistance is a very difficult clinical problem in treatment of bronchial asthma. Accumulating evidence indicated that interleukin 17A (IL-17A) level is upregulated in steroid resistant asthma and relevant to steroid sensitivity and disease severity. However, the underlying mechanism has not been well clarified. Our previous research demonstrated that IL-17A increased miR-200b-3p expression in primary alveolar macrophage, and miR-200b-3p could target DUSP1, a key regulator in MAPK signaling. To further investigate the role of miR-200b-3p/DUSP1 axis in IL-17A mediating glucocorticoids resistance in asthma, we intend to carry out a project in cells and animal models as follows: (1) To explore the mechanism underlying IL-17A-induced miR-200b-3p expression; (2) To clarify the role of miR-200b-3p in IL-17-induced steroid resistance; (3) To investigate the regulatory effects of miR-200b-3p on MAPK signaling and glucocorticoids sensitivity. This study would help to complement to the pathogenesis of asthma, and to provide a pathway in discovering novel drugs for asthma aiming at IL-17A.

糖皮质激素抵抗是支气管哮喘治疗中极为棘手的临床问题。大量研究表明，激素抵抗型哮喘患者体内白介素17A（IL-17A）水平较高，介导激素抵抗并与病情严重程度相关，但具体作用机制不明。本课题组前期研究发现：IL-17A可上调肺泡巨噬细胞中miR-200b-3p的表达，且初步证明miR-200b-3p可靶向作用于MAPK通路重要的调控蛋白DUSP1。为进一步明确miR-200b-3p/DUSP1信号轴在IL-17A介导哮喘糖皮质激素抵抗中的作用，本项目拟在细胞水平和动物模型中进行如下研究：①IL-17A上调miR-200b-3p表达的分子机制；②miR-200b-3p在IL-17A介导的激素抵抗中的作用；③miR-200b-3p对MAPK通路和激素敏感性的调控及分子机制。本研究不仅助于对哮喘发病机制的阐述作出补充，还可为针对IL-17A设计哮喘治疗的新型靶向药物提供思路。

糖皮质激素抵抗是支气管哮喘治疗中极为棘手的临床问题。大量研究表明，激素抵抗型哮喘患者体内白介素17A（IL-17A）水平较高，与病情严重程度相关并在介导激素抵抗中起到关键作用，但作用机制不明。本研究发现，IL-17A可上调肺泡巨噬细胞中miR-200b-3p的表达，miR-200b-3p水平在激素抵抗型哮喘小鼠模型和激素抵抗型哮喘患者的肺泡巨噬细胞中分别高于激素敏感型哮喘小鼠模型和激素敏感型哮喘病人。敲减p65或给予p65抑制剂可抑制IL-17A诱导的miR-200b-3p水平的升高，CHIP实验结果表明p65可结合miR-200b基因上游。通过慢病毒敲减miR-200b-3p可下调IL-17A和TNF-α刺激的肺泡巨噬细胞中p-JNK和p-p38水平，促进糖皮质激素受体α的入核，且恢复激素抵抗型哮喘小鼠模型对糖皮质激素的敏感性。过表达miR-200b-3p可上调TNF-α刺激的肺泡巨噬细胞中p-JNK和p-p38水平，抑制糖皮质激素受体α的入核，且导致激素敏感型哮喘小鼠模型对糖皮质激素产生抵抗性。进一步研究证明，miR-200b-3p可靶向作用于MAPK通路重要的调控蛋白DUSP1，在转录后水平下调其在肺泡巨噬细胞中的表达。过表达DUSP1后可抑制miR-200b-3p诱导的MAPK通路激活和哮喘的激素抵抗。综上，本研究结果表明IL-17A可通过激活NF-κB诱导miR-200b-3p在肺泡巨噬细胞中的表达，过表达的miR-200b-3p可下调靶点DUSP1的表达水平，导致MAPK通路的过度激活从而诱发哮喘糖皮质激素抵抗。本研究不仅对哮喘发病机制的阐述作出补充，还为针对IL-17A设计哮喘治疗的新型靶向药物提供思路。