SCF in Allergic Airway Inflammation

描述(申请人提供)：支气管周围白细胞聚集和激活是哮喘呼吸道反应发展过程中的一个主要疾病因素，导致慢性呼吸道疾病。特别是，嗜酸性粒细胞被报道为与诱导支气管损伤有关的主要群体，并被认为参与了上皮细胞损伤、粘液产生、支气管阻塞和呼吸道高反应性。在过去的几年里，我们的实验室一直在研究在蟑螂变应原诱导的反应中，在呼吸道中产生的干细胞因子(SCF)的新作用。我们的数据提供了与过敏反应的诱导直接相关的新发现。当SCF在呼吸道内被中和时，可以观察到与嗜酸性粒细胞聚集、嗜酸性粒细胞激活和粘液产生直接相关的长期变化。后一个方面将是此次续签申请的重点，研究将集中在一个主要概念上。我们的假设是，蟑螂变应原攻击后，呼吸道上皮细胞在气道内产生SCF，激活招募的嗜酸性粒细胞，上调炎症和生长因子，从而导致气道高反应性和粘液产生增加。将使用已建立的过敏性呼吸道疾病的体内模型和体外分析来研究产生SCF的上皮细胞和渗透的嗜酸性粒细胞之间的这种复杂的相互作用，以更好地确定反应的机制。为了验证这一假设，我们将重点研究呼吸道上皮细胞来源的干细胞因子诱导特定嗜酸性粒细胞相关功能的机制。我们的研究将1)确定SCF有助于慢性呼吸道疾病的发展，并确定其与嗜酸性粒细胞聚集和激活以及粘液产生的关系；2)确定SCF通过什么信号转导途径影响嗜酸性粒细胞的激活，从而导致随后的粘液产生；3)确定SCF诱导的功能在导致粘液产生的激活中具有特定的作用；4)研究上皮细胞来源的SCF如何影响嗜酸性粒细胞的激活；5)确定SCF激活的嗜酸性粒细胞通过什么机制改变粘液相关基因和蛋白的发育。为了评估SCF诱导的嗜酸性粒细胞激活导致呼吸道损伤、粘液产生和病理生理学的机制，我们将讨论一些以前未探索的机制。我们将特别集中在与导致嗜酸性粒细胞激活的不同SCF信号以及产生特异性炎症和粘液的细胞因子有关的那些方面。此外，我们还将评估正常和SCF缺陷过敏小鼠的呼吸道生理学变化，并阐明SCF诱导的嗜酸性粒细胞在慢性病发展过程中激活导致粘液过度产生的机制。我们的研究还将利用siRNA构建的新技术来抑制SCF诱导的嗜酸性粒细胞激活的特定方面。

DESCRIPTION (provided by applicant): Peribronchial leukocyte accumulation and activation is a major disease factor during development of asthmatic airway responses that leads to chronic airway disease. In particular, eosinophils have been reported to be primary populations associated with induction of bronchial injury, and are thought to participate in epithelial cell damage, mucus production, bronchial obstruction, and airway hyperreactivity. Over the past several years our laboratory has been investigating the novel role of stem cell factor (SCF) produced in the airway during cockroach allergen-induced responses. Our data has provided novel findings related directly to the induction of the allergic responses. When SCF is neutralized within the airway long-term changes can be observed related directly to eosinophil accumulation, eosinophil activation, and mucus production. This latter aspect will be the focus of this renewal application with studies centered on a principal concept. Our hypothesis is that airway epithelial cell production of SCF within the airway after cockroach allergen challenge activates recruited eosinophils upregulating inflammatory and growth factors that induce increased airway hyperreactivity and production of mucus. This complex interaction between SCF producing epithelial cells and infiltrating eosinophils will be investigated using both an established in vivo model of allergic airway disease and in vitro analysis to better identify the mechanism of the responses. To test this hypothesis we will focus on mechanisms involved in the ability of airway epithelial cell-derived SCF to induce specific eosinophil related functions. Our studies will 1) establish that SCF contributes to the development of chronic airway disease and define its relation to eosinophil accumulation and activation as well as mucus production, 2) define by what signal transduction pathways SCF influences eosinophil activation leading to subsequent mucus production in the airway, 3) determine that particular pathways have a specific role for SCF-induced functions leading to activation of mucus production 4) investigate how epithelial cell-derived SCF impacts on eosinophil activation, and 5) define by what mechanism SCF-activated eosinophils alter development of mucus-related genes and protein. To assess the mechanisms of SCF-induced eosinophil activation leading to airway damage, mucus production, and pathophysiology, we will address a number of previously unexplored mechanisms. We will especially concentrate on those pertaining to differential SCF signaling leading to eosinophil activation and specific inflammatory and mucus producing cytokines. In addition, we will assess changes in airway physiology in normal and SCF deficient allergic mice and elucidate the mechanism of SCF-induced eosinophil activation during chronic disease development leading to mucus overproduction. Our studies will also utilize new technology with siRNA constructs for inhibition of specific aspects of SCF-induced eosinophil activation.