Understanding Severe Asthma Using an Experimental Model

描述（由申请人提供）：重度哮喘是一种难以通过皮质类固醇（CS）控制的疾病，皮质类固醇仍然是哮喘治疗的主要药物。CS治疗的不同结果，即使在高剂量口服或胃肠外使用时，也表明两个哮喘亚类的炎症反应性质存在根本差异。为了了解促进CS难治性哮喘的机制和介质，我们开发了一种小鼠疾病模型，其中气道炎症和CS无反应性模拟人类严重哮喘表型，包括高IFN-γ/IFN-γ水平。Th 1、IL-27和IL-17应答。我们的模型涉及将小鼠暴露于过敏原（屋尘螨-HDM）和粘膜佐剂cyclic-di- GMP（c-di-GMP），以促进气道中的混合粒细胞浸润，并诱导显着更高的IFN-？和IL-17的反应 肺引流淋巴结和小鼠的肺，但与单独HDM诱导的相比，IL-13/IL-5应答较低。在HDM+c-di-GMP暴露小鼠中给予CS、地塞米松（Dex）并没有抑制IFN-γ/ IL-17/IL-13反应或气道嗜酸性粒细胞增多，但部分减弱嗜酸性粒细胞增多。这些小鼠的气道高反应性也仅被CS部分减弱。总的来说，我们的数据使我们假设：1）CS难治性哮喘是由高Th 1反应引起的，通常伴有促进气道嗜中性粒细胞的Th 17反应。2)从先天性细胞如树突状细胞（DC）产生的关键Th 1和Th 17偏斜细胞因子如IL-27和IL-12（Th 1）以及IL-6和IL-23（Th 17）的增加是Th 1和Th 17应答增强的基础。3)转录因子IRF 5最近参与了M1巨噬细胞产生IL-6、IL-12和IL-23，而STAT 1位于IFN和IL-27的下游，参与驱动Th 1和Th 17的发育。CS难治性重度哮喘可能涉及IFN-β，IL-27和Th 17细胞因子在严重哮喘中的作用尚未在先前的研究中得到认识或研究。为了解决我们的假设，我们将：目标1。研究Th 1和Th 17通路在促进以混合粒细胞气道炎症为特征的CS难治性重度哮喘表型中的作用。目标二。通过对先天性细胞的影响，确定暴露于HDM和c-di-GMP诱导高Th 1和Th 17应答的机制。目标3.确定IL-27在CS难治性重度哮喘表型的发生和持续中的细胞来源和作用。小鼠模型结合基因工程小鼠将使我们能够研究关键介质在促进严重哮喘表型中的作用。该模型将是有用的，以测试新的治疗方式，当他们成为可用的。此外，从这项研究中产生的RNA测序数据将确定SA中的新网络，以供将来在实验模型和翻译研究中进行询问。

DESCRIPTION (provided by applicant): Severe asthma is a difficult disease to control by corticosteroids (CSs), which remain the mainstay of asthma therapy. This differential outcome in response to CS therapy, even when used at a high dose orally or parenterally, suggests a fundamental difference in the nature of the inflammatory response in the two subclasses of asthmatics. To understand the mechanisms and mediators that promote CS-refractory asthma, we have developed a mouse model of disease in which both airway inflammation and CS-unresponsiveness mimic the severe asthma phenotype in humans including high IFN-?/Th1, IL-27 and IL-17 responses. Our model involves exposure of mice to an allergen (house dust mite-HDM) with a mucosal adjuvant, cyclic-di- GMP (c-di-GMP), to promote a mixed granulocytic infiltration in the airways with induction of significantly higher IFN-? and IL-17 responses in the lung-draining lymph nodes and the lungs of the mice but a lower IL-13/IL-5 response compared to that induced by HDM alone. Administration of the CS, dexamethasone (Dex), in HDM+c-di-GMP-exposed mice did not subdue the IFN-?/IL-17/IL-13 response or the airway neutrophilia but partially attenuated the eosinophilia. Airway hyperreactivity in these mice was also only partially attenuated by CS. Collectively, our data lead us to hypothesize that 1) CS-refractory asthma is orchestrated by a high Th1 response often accompanied by a Th17 response that promotes airway neutrophilia. 2) Increased production of key Th1- and Th17-skewing cytokines such as IL-27 and IL-12 (Th1) and IL-6 and IL-23 (Th17) from innate cells such as dendritic cells (DCs) underlies the heightened Th1 and Th17 response. 3) The transcription factors IRF5, recently implicated in IL-6, IL-12 and IL-23 production from M1 macrophages, and STAT1, downstream of IFNs and IL-27, are involved in driving Th1 and Th17 development. The idea that CS refractory severe asthma might involve collaboration between IFN-?, IL-27 and Th17 cytokines in severe asthma has not been appreciated or investigated in prior studies. To address our hypotheses we will: Aim 1. Investigate the role of the Th1 and Th17 pathways in promoting the CS-refractory severe asthma phenotype characterized by mixed granulocytic airway inflammation. Aim 2. Determine the mechanisms by which high Th1 and Th17 responses are induced by exposure to HDM and c-di-GMP via effects on innate cells. Aim 3. Identify the cellular source and role of IL-27 in initiation and perpetuation of CS-refractory severe asthma phenotype. The mouse model in conjunction with genetically engineered mice will allow us to investigate the role of key mediators in promoting the severe asthma phenotype. The model will be useful to test novel therapeutic modalities as and when they become available. Additionally, RNA sequencing data generated from this study will identify novel networks in SA for future interrogation in the experimental model and in translational studies.