Effects of ozone exposure on expression and function of surfactant protein D

描述（由申请人提供）：本申请是针对转化科学（15-ES-101*）的广泛挑战领域和“使用非人类模型的环境暴露对表型结果的影响”的特定挑战主题而提交的。慢性气道炎症性疾病，如哮喘或慢性阻塞性肺疾病（COPD）是遗传因素和环境暴露之间复杂的相互作用产生的。我们的实验室已经建立了模拟臭氧（O3）引起的气道炎症加重的病理小鼠模型。目前的应用将利用该模型以及基因敲除和条件过表达小鼠来研究表面活性剂蛋白D基因表达变化和翻译后修饰的重要性，表面活性剂蛋白D是近端和远端气道衬里的免疫保护成分。我们的研究表明，吸入常见的空气污染物O3，会导致过敏原致敏小鼠的哮喘变化显著加剧，同时出现异常的三聚体SP-D和活化的髓样树突状细胞。我们假设SP-D在气道炎症的发生和消退之间起着“主开关”的作用：天然SP-D是促炎树突状细胞激活的抑制因子，通过c端与负信号受体SIRP结合起作用。相反，经过O3氧化损伤的去寡聚（三聚体）SP-D通过连接胶原受体钙网蛋白/CD91，通过暴露的n端激活树突状细胞。由于成熟骨髓树突状细胞携带钙调蛋白/CD91的存在，哮喘气道特别容易受到臭氧诱导的SP-D分子变化的影响。目的1是研究臭氧诱导的过敏性气道炎症加剧与具有活性n端结构域的SP-D三聚体的出现有关的假设。目的2是研究天然SP-D与SIRP结合的假设。并传递抑制信号，而三聚体SP-D结合钙网蛋白/CD91并诱导树突状细胞释放NF-kB、TNF和TARC （Ccl17）的促炎激活。目的3是研究C末端是否抑制和三聚体SP-D是否激活骨髓源性促炎树突状细胞的上皮迁移。体外骨髓源树突状细胞培养和体内条件SP-D表达小鼠和腺相关病毒基因替代野生型和突变SP-D（模拟分子c末端或SP-D三聚体）将研究树突状细胞的成熟和迁移。该项目的结果将为SP-D在臭氧诱导的气道改变过程中对先天免疫系统的调节作用以及这种天然免疫保护剂在肺部的潜在治疗利用提供具有临床和科学意义的信息。

DESCRIPTION (provided by applicant): This application is submitted in response to the broad challenge area of Translational Science (15-ES-101*) and the specific challenge topic of "Effects of environmental exposures on phenotypic outcomes using non- human models." Chronic inflammatory diseases of the airways such as asthma or chronic obstructive pulmonary disease (COPD) arise from a complex interaction between genetic factors and environmental exposures. Our laboratory has established murine models that mimic the pathology of ozone (O3)-induced exacerbation of airway inflammation. The current application will utilize this model together with gene knockout and conditional over expressor mice to investigate the importance in changes in gene expression and post translational modifications of surfactant protein D, an immunoprotective component of the proximal and distal airway lining. Our studies showed that inhalation of O3, a common air pollutant, induced a significant exacerbation of the asthmatic changes in allergen sensitized mice together with the appearance of abnormal, trimeric SP-D and activated, myeloid dendritic cells. We hypothesize that SP-D acts as a "master switch" between the onset and resolution of airway inflammation: Native SP-D is a suppressor of activation of the proinflammatory dendritic cells and acts through the C-terminal by binding to the negative signal receptor SIRP. In contrast, a de-oligomerized (trimeric) SP-D that has undergone oxidative damage by O3, activates dendritic cells through the exposed N-terminal by ligating the collagen receptor, calreticulin/CD91. The asthmatic airways are particularly susceptible to O3-induced changes in the SP-D molecule because of the presence of mature myeloid dendritic cells carrying the calreticulin/CD91. Aim 1 is to investigate the hypothesis that O3-induced exacerbation of allergic airway inflammation is associated with the appearance of SP-D trimers with an active N-terminal domain. Aim 2 is to study the hypothesis that native SP-D binds to SIRP? and delivers inhibitory signals while trimeric SP-D binds to calreticulin/CD91 and induces proinflammatory activation of NF-kB, TNF and TARC (Ccl17) release by dendritic cells. Aim 3 is to investigate whether the C- terminal suppresses and the trimeric SP-D activates epithelial migration of bone marrow derived, proinflammatory dendritic cells. In vitro bone-marrow derived dendritic cell cultures and in vivo conditional SP-D expressing mice and adeno-associated virus gene replacement of wild-type and mutant SP-D (mimicking either the C-terminal of the molecule or the SP-D trimer) will be studied for maturation and migration of dendritic cells. Results of this project will yield clinically and scientifically significant information on the role of SP-D in regulation of the innate immune system during O3-induced airway changes and on potential therapeutic utilization of this naturally occurring immuno-protective agent in the lung. PUBLIC HEALTH RELEVANCE: Air pollution, particularly O3, induces exacerbations of asthma that substantially worsen morbidity and mortality. In healthy individuals inhalation of O3 elicits mechanisms such as homeostatic increase in SP-D synthesis that protect the lung from development of chronic damage. Currently neither the mechanism of O3-induced SP-D production nor the consequent alterations of the pulmonary immune system is understood. Results from this application will define the implications of SP-D in O3-induced exacerbation of asthma and will provide novel approaches to manipulate the pulmonary immune system.