Functional Genomics of IL-33 expression and asthma risk

IL-33 表达和哮喘风险的功能基因组学

• 批准号: 8721683
• 负责人: Marcelo A. Nobrega
• 金额: $ 71.63万
• 依托单位: UNIVERSITY OF CHICAGO
• 依托单位国家: 美国
• 财政年份: 2014
• 资助国家: 美国
• 起止时间: 2014-04-01 至 2018-03-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8721683
• 关键词: Affect; African; Alleles; Allergens; Asthma; Basic Science; Binding; Binding Sites; Biological Assay; CD14 gene; CD8B1 gene; Cell Line; Cells; Clinical Medicine; Computer Simulation; Data; Databases; Elements; Enhancers; Epigenetic Process; Epithelial Cells; Etiology; Family; Gene Expression; Genes; Genetic Enhancer Element; Genetic Polymorphism; Goals; Hematopoietic; Human; In Vitro; Individual; Inflammation; Interleukin-1; Leukocytes; Luciferases; Lung; Lung diseases; Lymphoid Cell; Mammalian Cell; Meta-Analysis; Molecular; Mus; Pattern; Play; Population; Positioning Attribute; Predisposition; Regulation; Regulatory Element; Risk; Role; Scanning; T-Lymphocyte; Testing; Th2 Cells; Tissues; Viral Physiology; Zebrafish; cytokine; functional genomics; genetic variant; genome database; genome wide association study; in vivo; innovation; interest; monocyte; novel; public health relevance; receptor

DESCRIPTION (provided by applicant): Asthma affects an estimated 300 million people worldwide and represents an important challenge for basic science to benefit clinical medicine. Recently, two independent meta-analysis of genome wide association studies GWAS data have identified the genes encoding the IL-1¿ family cytokine, IL-33, and its receptor, IL1RL1 (ST2), as susceptibility loci for asthma. A plethora of functions have been attributed to IL-33 including activation of type-2 innate lymphoid cells, expansion of Th2 cells, and augmentation of anti-viral function of CD8 T cells. As the cellular and molecular mechanisms connecting IL-33 to asthma etiology become the focus of intense scrutiny, several basic questions remain unanswered. This application focuses on elucidating the regulation of human IL33 expression, both at the transcriptional level as well as the organismal level. While IL33 is known to be constitutively expressed in epithelial cells and structural cells, we and others have recently found IL-33 produced by murine hematopoietic cells. We now demonstrate that IL33 is expressed in human lung leukocytes and that allergens induce IL33 expression in human CD14+ monocytes. These findings suggest a new paradigm of IL33 expression in the lungs, and represent an innovative opportunity to understand the impact tissue specific expression of this cytokine in airway Th2 inflammation. Using ENCODE and 1000 Genomes databases, we have performed in silico interrogation of the regulatory epigenetic landscape of the IL33 locus and have identified two regions of high interest; one region has strong enhancer activity, and a second region contains two defined CTCF binding sites, suggestive of insulator activity. We now demonstrate that the first region can function as an enhancer, and importantly, this activity is modified by a SNP found specifically in individuals of African ancestry. However useful, these public databases fail to highlight regulatory elements that only become evident after induction of gene expression by environmental stimulation. Thus, regulation of IL33 expression in primary cells after allergen stimulation will likely elucidate novel regulatory elements not realized in static cell lines. The central hypothesis of our study posits that noncoding genetic variants within regulatory elements alter the temporal and spatial expression patterns of IL33, and that this is a central mechanism behind the association of SNPs at the IL33 locus with asthma risk. To test this hypothesis the following aims are proposed: 1) identify the epigenetic changes that occur upon IL33 gene expression in stimulated hematopoietic cells and bronchial epithelial cells.; 2) determine the role the enhancer element(s) play in the regulation of IL33 expression; and 3) determine the role of CTCF in IL33 expression.

描述（由申请人提供）：哮喘影响全球约 3 亿人，是基础科学造福临床医学的一项重要挑战。最近，对全基因组关联研究 GWAS 数据进行的两项独立荟萃分析已确定编码 IL-1¿ 家族细胞因子 IL-33 及其受体 IL1RL1 (ST2) 的基因为哮喘易感位点。 IL-33 具有多种功能，包括激活 2 型先天淋巴细胞、扩增 Th2 细胞以及增强 CD8 T 细胞的抗病毒功能。随着将 IL-33 与哮喘病因联系起来的细胞和分子机制成为密切关注的焦点，一些基本问题仍未得到解答。该应用的重点是阐明人类 IL33 表达的调控，包括转录水平和生物水平。虽然已知 IL33 在上皮细胞和结构细胞中组成型表达，但我们和其他人最近发现 IL-33 由小鼠造血细胞产生。我们现在证明 IL33 在人肺白细胞中表达，并且过敏原诱导人 CD14+ 单核细胞中 IL33 的表达。这些发现提出了肺部 IL33 表达的新范例，并为了解该细胞因子在气道 Th2 炎症中的组织特异性表达的影响提供了一个创新机会。使用 ENCODE 和 1000 Genomes 数据库，我们对 IL33 基因座的表观遗传调控景观进行了计算机模拟分析，并确定了两个高度感兴趣的区域；第一个区域具有强增强子活性，第二个区域包含两个确定的 CTCF 结合位点，表明具有绝缘子活性。我们现在证明第一个区域可以作为增强子发挥作用，重要的是，这种活动是由专门在非洲血统个体中发现的 SNP 修改的。无论多么有用，这些公共数据库都未能强调只有在环境刺激诱导基因表达后才变得明显的调控元件。因此，过敏原刺激后原代细胞中 IL33 表达的调节可能会阐明静态细胞系中未实现的新调节元件。我们研究的中心假设认为，调控元件内的非编码遗传变异改变了 IL33 的时间和空间表达模式，这是 IL33 位点上的 SNP 与哮喘风险关联背后的核心机制。为了检验这一假设，提出了以下目标：1) 鉴定受刺激的造血细胞和支气管上皮细胞中 IL33 基因表达时发生的表观遗传变化。 2）确定角色 增强子元件在 IL33 表达的调节中发挥作用； 3)确定CTCF在IL33表达中的作用。