The Role of Gelatinase B in Terminal Airway Remodeling

描述(申请人提供)：在许多慢性肺部疾病中，终末气道是结构和功能异常的部位，最明显的是COPD，但对终末呼吸道衬里上皮细胞的细胞和分子生物学知之甚少。最近的研究表明，基质金属蛋白酶明胶酶B(MMP9；Gel B)在终末呼吸道上皮细胞的功能中起着重要作用。凝胶B基因缺陷(“基因敲除”)小鼠在接触博莱霉素后没有表现出野生型小鼠的肺泡毛细支气管化，也没有表现出在暴露于NAT后末端呼吸道上皮的正常快速修复，NAPAN是一种导致末端呼吸道内Clara细胞坏死的介质。Gel B在终末呼吸道上皮细胞中的表达调控尚不清楚。最近的研究表明，细胞外基质金属蛋白酶诱导物EMMPRIN在人肺纤维化和小鼠气管内注射博莱霉素后的肺泡和终末气道上皮细胞中显著表达。拟进行的研究将检测：(1)Clara细胞表达凝胶B是否能修复博莱霉素诱导的细支气管化和萘凝胶修饰后的上皮修复；(2)凝胶B的迁移特性，以及凝胶B与Clara细胞迁移的关系；(3)EMMPRIN对肺细胞和完整肺组织基质金属蛋白酶，尤其是凝胶B表达的影响。为了评价Clara细胞凝胶B在博莱霉素诱导的肺泡毛细支化和四环素诱导的终末气道修复中的作用，我们将在凝胶B基因敲除的背景上建立转基因小鼠，在Clara细胞中以四环素诱导的方式表达凝胶B。为了研究Clara细胞的迁移和凝胶B的作用，我们将从凝胶B缺乏的野生型小鼠中分离Clara细胞，并对其对各种趋化因子的反应以及与各种细胞外基质成分的接触的迁移进行量化。为了确定EMMPRIN是否影响凝胶B和其他基质金属蛋白酶的表达，将各种类型的肺细胞，包括Clara细胞，暴露于重组EMMPRIN中，并评估基质金属蛋白酶的表达。综上所述，建议的研究将有助于更好地了解末端呼吸道上皮的生物学，这是许多慢性肺部疾病，特别是COPD的中心部位。

DESCRIPTION (provided by applicant): The terminal airways are sites of abnormal structure and function in a number of chronic lung disorders, most notably COPD, yet relatively little is known about the cell and molecular biology of the epithelial cells lining terminal airways. Recent observations indicate an important role of the matrix metalloproteinase gelatinase B (MMP-9; gel B) in the function of terminal airway epithelium. Gel B-deficient ("knockout") mice do not show the alveolar bronchiolization seen in wild type mice after exposure to bleomycin, nor do they show the normal rapid repair of terminal airway epithelium after exposure to napthalene, an agent that causes necrosis of the Clara cells lining the terminal airways. The regulation of gel B expression in terminal airway epithelium is not well understood. Recent studies have shown that extracellular matrix metalloproteinase inducer, EMMPRIN, is prominent in alveolar and terminal airway epithelium in human pulmonary fibrosis and after intratracheal bleomycin in mice. The studies proposed will examine: (1) whether gel B expression by Clara cells can rescue the defects in alveolar bronchiolization after bleomycin and epithelial repair after napthalene in gel B "knockout" mice; (2) the migratory properties of Clara cells and the relationship of gel B to Clara cell migration; and (3) the effects of EMMPRIN on the expression of matrix metalloproteinases, especially gel B, by lung cells and the intact lung. To assess the role of Clara cell gel B on alveolar bronchiolization after bleomycin and terminal airway repair after napthalene, transgenic mice will be generated on the gel B knockout background which will express gel B in Clara cells in a tetracycline-inducible manner. To study the migration of Clara cells and the role of gel B, Clara cells will be isolated from gel B-deficient and wild type mice and their migration quantified in response to various chemotactic factors and in relation to contact with various extracellular matrix components. To determine whether EMMPRIN affects expression of gel B and other matrix metalloproteinases, various types of lung cells, including Clara cells, will be exposed to recombinant EMMPRIN and evaluated for matrix metalloproteinase expression. Taken together, the studies proposed will contribute to better understanding of the biology of terminal airway epithelium, a site that is central in many chronic lung disorders, especially COPD.