Recognition of microbes by NKT cells at the lung mucosal surface

描述(由申请人提供)：本申请涉及广泛的挑战领域(04)临床研究，以及具体的挑战主题04-AI-101：发展新的方法和解决粘膜免疫学的关键问题。该项目的长期目标是了解自然杀伤T(NKT)细胞如何识别呼吸道粘膜中的微生物并对其做出反应。我们和其他人之前已经证明，肺中的NKT细胞在呼吸道炎症和哮喘的发展中发挥关键作用。此外，我们还发现来自神经鞘氨醇单胞菌的糖脂可以直接激活小鼠的肺NKT细胞，并诱导呼吸道炎症和气道高反应性(AHR)，这是哮喘的主要特征。这些结果表明，肺粘膜中的NKT细胞可能对进入肺的其他微生物产生反应，并且NKT细胞可能在调节肺粘膜免疫反应中发挥先前未被怀疑的关键作用。虽然大多数哮喘患者的肺被认为是无菌的，但我们有强有力的和令人惊讶的初步数据表明，实际上在很大一部分哮喘患者的肺中存在高度多样化的复杂细菌联合体，这是通过一种极其敏感的、新型的基于非培养的16S rRNA PhyloChip芯片芯片方法检测到的。存在的微生物包括肺炎链球菌，以及以前没有通过培养技术检测到的细菌，如少突神经鞘氨醇单胞菌，它表达可以激活NKT细胞的糖脂。基于这些研究，我们认为慢性肺炎性疾病患者的呼吸道粘膜中的微生物比以前认识的要常见得多。此外，虽然只有几种已知的微生物可以激活NKT细胞，但基于强大的初步数据，我们假设许多肺部微生物，包括肺炎链球菌、头盖伯克霍尔德氏菌、少突鞘氨醇单胞菌和烟曲霉都表达糖脂，可以激活NKT细胞，导致先天性和获得性粘膜免疫反应。因此，我们认为，宿主对支气管内粘膜中常见的以及以前未被识别的微生物的反应可以在呼吸道中引发慢性疾病。在这个项目中，我们建议从肺炎链球菌、阴沟肠杆菌和烟曲霉菌中鉴定能够直接激活NKT细胞的糖脂。这些研究将展示一种特定的机制，通过这种机制，肺部存在的微生物可以激活NKT细胞，并引发AHR、炎症和哮喘。我们的研究将极大地扩大对针对呼吸道粘膜中存在的微生物而产生的免疫反应类型的基本了解，以及这些反应如何导致慢性肺部疾病的发展，如哮喘。 公共卫生相关性：这些研究的结果将直接影响我们对呼吸道粘膜中发生的免疫反应的基本理解。我们建议理解一种新的细胞类型，称为自然杀伤T细胞，如何从根本上调节对呼吸道微生物的先天和获得性免疫。这些研究将补充我们正在进行的其他研究，这些研究得到了其他赠款的支持，并使用了一种新的、高度敏感的非培养分子方法，以确定哮喘等慢性肺病患者肺部存在的微生物。这些结果将使人们更好地了解粘膜对呼吸道微生物的免疫，以及这些免疫反应如何导致呼吸道炎症和慢性肺部疾病的发展，如哮喘和慢性阻塞性肺病。

DESCRIPTION (provided by applicant): This application addresses broad Challenge Area (04) Clinical Research, and the specific Challenge Topic, 04-AI-101: Develop novel methods and address key questions in mucosal immunology. The long-term goal of this project is to understand how natural killer T (NKT) cells recognize and respond to microorganisms in the respiratory mucosa. We and others have previously shown that NKT cells in the lungs play a critical role in the development of airway inflammation and asthma. In addition, we have shown that glycolipids from the bacterial species Sphingomonas can directly activate pulmonary NKT cells in mice and induce airway inflammation and airway hyperreactivity (AHR), a cardinal feature of asthma. These results suggest that NKT cells in the lung mucosa may respond to other microorganisms that enter the lung, and that NKT cells could play a previously unsuspected critical role in regulating pulmonary mucosal immune responses. Although the lungs of most patients with asthma are thought to be sterile, we have strong and surprising preliminary data indicating that a highly diverse complex bacterial consortia are in fact present in the lungs of a large fraction of patients with asthma, as detected with an extremely sensitive, novel non-culture based 16S rRNA PhyloChip microarray method. The microorganisms present include Streptococcus pneumoniae, as well as bacteria not previously detected by culture-based techniques, such as Sphingomonas paucimobilis, which express glycolipids that can activate NKT cells. Based on these studies, we suggest that microorganisms are much more common in the airway mucosa of patients with chronic pulmonary inflammatory diseases than previously recognized. Furthermore, while only a few microorganisms are known to activate NKT cells, based on strong preliminary data, we hypothesize that many pulmonary microorganisms, including S. pneumoniae, Burkholderia cenocepacia, Sphingomonas paucimobilis and Aspergillus fumigatus express glycolipids that can activate NKT cells, resulting in innate and adaptive mucosal immune responses. We therefore believe that host responses to common, as well as previously unrecognized, microorganisms in the endobronchial mucosa can trigger chronic diseases in the airways. In this project, we propose to identify glycolipids from S. pneumoniae, B. cenocepacia, and A. fumigatus that can directly activate NKT cells. These studies will demonstrate a specific mechanism by which microorganisms present in the lungs can activate NKT cells and induce AHR, inflammation and asthma. Our studies will greatly expand the fundamental understanding of the types of immune responses that develop against microorganisms present in the respiratory mucosa, and how these responses result in the development of chronic lung diseases, such as asthma. PUBLIC HEALTH RELEVANCE: The results of these studies will have a direct impact on our fundamental understanding of the immune responses that occur in the respiratory mucosa. We propose to understand how a novel cell type, called natural killer T cells, fundamentally regulates innate and adaptive immunity to respiratory microorganisms. These studies will complement additional studies that we are performing, supported by other grants and using a novel, highly sensitive non-culture molecular method, to define the microorganisms that are present in the lungs of patients with chronic lung disease, such as asthma. These results will provide a much greater appreciation and understanding of mucosal immunity to microorganisms present in the respiratory tract, and how these immune responses lead to respiratory inflammation and to the development of chronic lung diseases, such as asthma and COPD.