Regulation of Mucous Cell Metaplasia in Asthma

哮喘中粘液细胞化生的调节

• 批准号: 6908308
• 负责人: Yohannes Tesfaigzi
• 金额: $ 49.18万
• 依托单位: LOVELACE BIOMEDICAL & ENVIRONMENTAL RESEARCH INSTITUTE
• 依托单位国家: 美国
• 财政年份: 2003
• 资助国家: 美国
• 起止时间: 2003-07-01 至 2007-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6908308
• 关键词: BCL2 gene /protein; Bax gene /protein; apoptosis; asthma; biological signal transduction; bronchial mucus; bronchioles; chronic bronchitis; clinical research; gel mobility shift assay; gene expression; human subject; human tissue; inflammation; interferon gamma; interleukin 13; interleukin 4; laboratory mouse; lung lavage; metaplasia; ovalbumin; postmortem; respiratory epithelium; tissue /cell culture; transcription factor

DESCRIPTION (provided by applicant): Clinical manifestations of asthma result in part from chronic inflammation that leads to mucous cell metaplasia (MCM), the appearance of mucous cells in peripheral airways that are normally devoid of these cells. In a mouse model of asthma, systemic immunization with ovalbumin (OVA) followed by repeated exposures to OVA aerosols initially induces inflammation and MCM, while prolonged exposures cause increase of IFNgamma levels and resolution of MCM. Instillation of IFNgamma in allergen-exposed mice induces expression of Bax, a pro-apoptotic protein, and accelerates the resolution of MCM by causing apoptosis. Mice deficient in Bax or Stat 1, an obligatory signaling molecule for IFNgamma, do not resolve MCM during prolonged exposures to allergen. IL-13 inhibits IFNgamma-induced Bax expression and apoptosis in mucous cells of mice and in normal human bronchial epithelial cells (HBEs). Our guiding hypothesis is that IL-13 induces MCM and counteracts the role of IFNgamma to activate Stat 1 and induce apoptosis through a Bax-mediated pathway in metaplastic mucous cells. In Aim 1, we will determine the pathway by which IL-13 inhibits IFNgamma signaling and Bax mediated resolution of MCM. We will determine whether IL-13 directly inhibits Bax expression or activates Stat 3, which is known to cause expression of anti-apoptotic proteins, Bcl-2 and BcI-lxL. Furthermore, we will determine whether IL-13 requires signaling through IL-4Ralpha and Stat 6 to inhibit IFNgamma-induced Bax expression. In Aim 2, we will determine the pathway by which IFNgamma induces Bax expression in allergen-induced MCM and whether the Bax-mediated pathway is essential to resolve MCM. We will investigate whether IFNgamma signals through IFN(R and Stat 1 to induce Bax in allergen-induced MCM and whether IFN( induces surface expression of IL-13Ralpha2 to inhibit IL-13 signaling through Stat 6. We will determine the requirement of Bax in decreasing MCM by instilling IFNgamma in Bax-deficient mice that have allergen-induced MCM. Our preliminary results with human autopsy tissues and bronchial brushings show that Bax is expressed in mucous cells from non-asthmatics and is absent in asthmatics. Therefore, in Aim 3, we will determine whether inflammatory mediators from asthmatics suppress expression of Bax and enhance mucous cell survival. The difference in the percentages of Bax-expressing cells among subjects with asthma, chronic bronchitis, and controls without respiratory diseases will be investigated using autopsy tissues and bronchial brushings. Furthermore, we will determine the effect of bronchoalveolar lavage fluid in inducing MCM and Bax expression in HBEs. These studies will provide new strategies to reduce mucous cell numbers in asthmatic patients.

描述（由申请人提供）： 哮喘的临床表现是由于慢性炎症导致粘液细胞化生（MCM）的一部分，这是通常没有这些细胞的外周气道中粘液细胞的出现。 在哮喘的小鼠模型中，用卵巢蛋白（OVA）进行全身免疫，然后反复暴露于OVA气溶胶最初会诱发炎症和MCM，而延长暴露会导致IFNGAMMA水平的增加和MCM的分辨率。在过敏原暴露的小鼠中滴注IFNGAMMA会诱导促凋亡蛋白的Bax表达，并通过引起细胞凋亡来加速MCM的分辨率。缺乏BAX或STAT 1的小鼠是IFNGAMMA的强制性信号分子，在长期暴露于过敏原的情况下无法解析MCM。 IL-13抑制IFNGAMMA诱导的小鼠粘液细胞和正常人支气管上皮细胞（HBE）中的BAX表达和凋亡。我们的指导假设是IL-13诱导MCM并抵消IFNGAMMA激活STAT 1并通过Bax介导的型粘液细胞中的途径诱导凋亡的作用。在AIM 1中，我们将确定IL-13抑制IFNGAMMA信号传导和BAX介导的MCM分辨率的途径。我们将确定IL-13是否直接抑制BAX表达或激活STAT 3，这已知会导致抗凋亡蛋白BCl-2和BCI-LXL的表达。此外，我们将确定IL-13是否需要通过IL-4ralpha和STAT 6信号传导才能抑制IFNGAMMA诱导的BAX表达。在AIM 2中，我们将确定IFNGAMMA在过敏原诱导的MCM中诱导BAX表达的途径，以及BAX介导的途径是否对于解决MCM至关重要。 We will investigate whether IFNgamma signals through IFN(R and Stat 1 to induce Bax in allergen-induced MCM and whether IFN( induces surface expression of IL-13Ralpha2 to inhibit IL-13 signaling through Stat 6. We will determine the requirement of Bax in decreasing MCM by instilling IFNgamma in Bax-deficient mice that have allergen-induced MCM. Our preliminary results with human尸检组织和支气管刷表明，在非心脏病的粘液细胞中表达了Bax，并且在AIM 3中不存在，我们将在AIM 3中确定哮喘患者的炎症介导者是否会抑制Bax表达的表达，并且在没有粘液细胞的差异的情况下，炎症。疾病将使用尸检组织和支气管刷。