IL-18 Signaling and Lung Epithelial Cell Barrier Integrity in Severe Asthma

项目总结/摘要： 哮喘是一种常见疾病，影响全球3亿多人。虽然控制得很好 在大多数情况下，一些人经历了标准治疗如皮质类固醇难治性疾病。最近 致力于了解这些严重哮喘（SA）患者的努力表明存在异质性。 严重哮喘研究计划（SARP）队列的先前工作将上皮基因签名与哮喘相关。 临床表型我们重新审视了这一数据集，并确定了3个新的哮喘患者群体，其中之一是， 大部分SA病例均存在，肺功能最差，加重史最多。使用 在数据集中的主要驱动因素，我们发现白细胞介素18受体（IL 18 R1）的表达， 沿着其他18个基因能够识别高危哮喘患者。IL 18 R1以前与哮喘有关， 全基因组关联研究。其配体白细胞介素-18（IL-18）可能是Th 1和Th 2的辅助因子 炎症在哮喘患者的血清和痰中检测到高IL-18水平，包括那些患有哮喘的患者。 致命的哮喘重要的是，IL-18和IL-18 R1调节其他炎性细胞中的上皮屏障功能。 条件我们已经证实，与健康人相比，SA患者的IL 18 R1在蛋白水平上增加。 对照组（HC）使用非常严重的哮喘病例的肺活检。这些SA患者还携带增加的 数IL-18+细胞，IL 18 R1的同源配体。IL 18刺激的下游靶标，包括 JNK 1和c-Jun的活性磷酸化形式显示SA气道上皮增加。患者也 显示粘附连接的紊乱，表明上皮屏障完整性的破坏。 基于这一背景和我们的初步数据，我们假设IL-18通路的激活，通过 支气管上皮中IL 18 R1表达升高，促进屏障功能失调， SA病理生物学通过增加免疫细胞获得外来抗原。我们提出两个目标来解决这个问题： 目标1。我们将询问预先存在的组织库以进行IL 18 R1的定量分析，并将其与 这些患者的组织和体液中的配体水平。这些数据将与以下活动相证实： 相关的信号通路和紧密/粘附连接完整性。 目标二。我们将使用原代人气道上皮细胞，通过支气管镜从HC和哮喘患者中获得， 患者从机械上确认和扩展目标1的结果。这将包括确认前 体内结果以及屏障功能的定量。 这些数据将确定IL 18在严重哮喘发病机制中的新作用，并开辟新的途径 来治疗这种既困难又昂贵的疾病。该项目的活动将为PI提供宝贵的 在获得、培养和操作原代人气道上皮细胞方面的经验， 通过整合计算生物学和免疫学的研究，为未来的体内工作奠定基础。

PROJECT SUMMARY/ABSTRACT: Asthma is a common disease, affecting more than 300 million people worldwide. Though well controlled in most, some experience disease that is refractory to standard treatments such as corticosteroids. Recent efforts focused on understanding these severe asthma (SA) patients suggests ontological heterogeneity. Previous work from the Severe Asthma Research Program (SARP) cohort linked epithelial gene signature to clinical phenotype. We revisited this data set and identified 3 novel groups of asthmatics, one of which housing the majority of SA cases and having the worst lung function and greatest exacerbation history. Using principal drivers of variance in the data set, we found that expression of the interleukin 18 receptor (IL18R1) along with 18 other genes was able identify at-risk asthmatics. IL18R1 has been previously linked to asthma in genome-wide association studies. Its ligand, interleukin-18 (IL-18), may be a cofactor for both Th1 and Th2 inflammation. High IL-18 levels have been detected in serum and sputum of asthmatics including in those with fatal asthma. Importantly, IL-18 and IL18R1 regulate epithelial barrier function in other inflammatory conditions. We have confirmed an increase in IL18R1 at the protein level in SA patients compared to healthy controls (HC) using lung biopsies from very severe asthma cases. These SA patients also harbor increased numbers IL-18+ cells, the cognate ligand for IL18R1. Downstream targets of IL18 stimulation, including the active phosphorylated forms of JNK1 and c-Jun, show increase in SA airway epithelium. SA patients also show disorganization of adherens junctions, suggesting breakdown in epithelial barrier integrity. Based on this background and our preliminary data, we hypothesize that IL-18 pathway activation, via elevated IL18R1 expression in bronchial epithelium, promotes dysregulated barrier function that contributes to SA pathobiology by increasing immune cell access to foreign antigens. We propose 2 aims to address this: Aim 1. We will interrogate pre-existing tissue banks for quantitative analysis of IL18R1 and compare that with levels of its ligand in tissue and fluids from these patients. These data will be corroborated with activity of associated signaling pathways and tight/adherens junction integrity. Aim 2. We will us primary human airway epithelial cells, obtained bronchoscopically from HCs and asthmatic patients to mechanistically confirm and expand upon the results from Aim 1. This will include validation of ex vivo results as well as quantification of barrier function. These data will identify a novel role for IL18 in severe asthma pathogenesis and open up new avenues for treatment of this difficult and costly disease. The activities of the project will provide the PI with valuable experience in obtaining, culturing and manipulating primary human airway epithelial cells and lay the foundation for future in vivo work by integrating study in computational biology and immunology.