Surfactant Protein-A regulation of eosinophil apoptosis in asthma

描述（由申请人提供）：哮喘是一种慢性疾病，其患病率正在增加，并对美国和世界许多地区的医疗保健造成相当大的负担。随着哮喘诊断率的提高和对哮喘患者亚群对治疗反应不同的认识的不断发展，人们认为通过将临床哮喘表型与特异性靶向生物疗法相匹配可以找到更好的治疗方法。嗜酸性粒细胞，通常存在于相对较少的数量在健康个体，成为主要的效应细胞在哮喘。尽管过敏性哮喘中嗜酸性粒细胞水平升高的证据充分，但调节嗜酸性粒细胞凋亡和过敏性气道消退的机制仍然是个谜。表面活性蛋白（SP）-A，由常驻肺细胞分泌的蛋白质，在宿主防御中起关键作用。我们的初步研究结果表明，SP-A与嗜酸性粒细胞相互作用，抑制脱粒，促进凋亡。SP-A的遗传变异存在于人群中，可能与肺部疾病有关。我们发现特异性SP-A变体在调节嗜酸性粒细胞活性方面不太有效。因此，我们假设SP-A内的特定基序通过受体识别和特异性信号传导事件直接启动嗜酸性粒细胞凋亡来促进过敏性气道炎症的消退。此外，在哮喘肺中，SP-A的遗传变异导致嗜酸性粒细胞凋亡受损，从而导致持续的嗜酸性气道炎症。我们将通过三个特定的目标来检验我们的假设：目的1）确定SP-A诱导嗜酸性粒细胞凋亡的机制，目的2）确定SP-A等位基因变体差异介导嗜酸性粒细胞凋亡的机制，目的3）确定SP-A基因型是否有助于哮喘的临床嗜酸性表型。我们的研究团队已经做好准备在小鼠和人类中进行这些创新性研究，这些研究将结合使用新型人源化SP-A转基因小鼠，SP-A2等位基因变体肽片段和SP-A变体寡聚体来测试我们的假设。我们预计，我们的方法将定义的分子和功能之间发生的相互作用，SP-A和嗜酸性粒细胞调节过敏性气道反应的决议。因此，我们相信，从这个应用程序中产生的数据将提供所需的基础表面活性剂蛋白为基础的疗法，以治疗嗜酸性粒细胞为主的哮喘的个人。

DESCRIPTION (provided by applicant): Asthma is a chronic disease, which is increasing in prevalence, and imposes a considerable burden on health care in the United States and in many regions around the world. The increasing rate of asthma diagnosis and the evolving knowledge that subsets of asthmatics respond differently to therapies, has led to the notion that a better approach to treatment may be found by matching clinical asthma phenotypes with specifically targeted biologic therapeutics. Eosinophils, usually present in relatively small numbers in healthy individuals, become predominant effector cells in asthma. Despite the well-documented presence of elevated levels of eosinophils in allergic asthma, the mechanisms regulating eosinophil apoptosis and resolution of allergic airways remain enigmatic. Surfactant protein (SP)-A, a protein secreted by resident lung cells, plays a critical role in host defense. Our preliminary findings show that SP-A interacts with eosinophils to repress degranulation and promote apoptosis. Genetic variants of SP-A exist in the population and may be associated with lung disease. We have found that specific SP-A variants are less effective at regulation of eosinophil activities. Therefore, we hypothesize that specific motifs within SP-A facilitate resolution of allergic airways inflammation by directly initiating eosinophil apoptosis through receptor recognition and specific signaling events. Furthermore, in the asthmatic lung, genetic variation of SP-A results in impaired eosinophil apoptosis and therefore persistent eosinophilic airways inflammation. We will test our hypothesis with three specific aims: Aim 1) Determine the mechanisms by which SP-A induces eosinophil apoptosis, Aim 2) Determine the mechanisms by which SP-A allelic variants differentially mediate eosinophil apoptosis, Aim 3) Determine whether the SP-A genotype contributes to the clinical eosinophilic phenotype of asthma. Our research team is well poised to conduct these innovative studies in mouse and man that will incorporate the use of novel humanized SP-A transgenic mice, SP-A2 allelic variant peptide fragments and SP-A variant oligomers to test our hypotheses. We anticipate that our approach will define the molecular and functional interactions that occur between SP-A and eosinophils in regulating resolution of allergic airway responses. Consequently, we believe that the data generated from this application will provide the groundwork needed for surfactant protein-based therapies to treat individuals with eosinophil predominant asthma.