NKT cells recognize and respond to microbes at mucosal surfaces

描述(申请人提供)：这个项目的长期目标是了解自然杀伤T(NKT)细胞如何识别和响应呼吸道粘膜中的微生物。我们之前已经证明，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。虽然目前已知只有少数几种微生物能激活NKT细胞，但基于强大的初步数据，我们认为许多肺部微生物，包括肺炎链球菌、头孢伯克霍尔德氏菌、少突鞘氨醇单胞菌和烟曲霉菌都表达糖脂，可以激活NKT细胞，导致先天性和获得性粘膜免疫反应。此外，我们假设，在慢性肺炎性疾病患者的呼吸道粘膜中，如少突神经鞘氨醇单胞菌等微生物比以前认识的要常见得多，宿主对这些以前未被识别的微生物在支气管腔内粘膜中的反应可引发呼吸道慢性疾病。因此，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，从而证明这些微生物可以激活NKT细胞并诱导AHR、炎症和哮喘的特定机制。此外，为了证明这些机制的临床相关性，我们建议使用一种极其敏感的、新颖的基于非培养的16S rRNA植物芯片微阵列方法来检查慢性肺部疾病(例如哮喘)患者的肺部细菌的存在，该方法使用大约500,000个探针来检测9,000个细菌的16S核糖体RNA特征。令人惊讶的是，初步数据显示，在很大一部分哮喘患者的肺中确实存在高度多样化的复杂细菌联合体，包括肺炎链球菌，以及以前通过培养技术未检测到的细菌，如鞘氨醇单胞菌(表达可激活NKT细胞的糖脂)。我们组建了一支优秀的研究团队，其中包括肺部生物学、脂质生物化学、微生物学和免疫学方面的专家。使用非常新的技术，我们产生了令人兴奋的初步数据，这表明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。

DESCRIPTION (provided by applicant): 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 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 only a few microorganisms are known to activate NKT cells, based on strong preliminary data, we believe that many pulmonary microorganisms, including Streptococcus pneumoniae, Burkholderia cenocepacia, Sphingomonas paucimobilis and Aspergillus fumigatus express glycolipids that can activate NKT cells, resulting in innate and adaptive mucosal immune responses. Furthermore, we hypothesize that microorganisms such as Sphingomonas paucimobilis, are much more common in the airway mucosa of patients with chronic pulmonary inflammatory diseases than previously recognized, and that host responses to these previously unrecognized microorganisms in the endobronchial mucosa can trigger chronic diseases in the airways. We therefore propose to identify glycolipids from S. pneumoniae, B. cenocepacia, and A. fumigatus that can directly activate NKT cells, thus demonstrating a specific mechanism by which these microorganisms can activate NKT cells and induce AHR, inflammation and asthma. Further, to demonstrate the clinical relevance of such mechanisms, we propose to examine the lungs of patients with chronic lung disease (e.g., asthma) for the presence of bacteria, using an extremely sensitive, novel non-culture based 16S rRNA PhyloChip microarray method, which uses approximately 500,000 probes to detect the 16S ribosomal RNA signatures from 9,000 bacteria. Surprisingly, preliminary data indicate that a highly diverse complex bacterial consortia, including S. pneumoniae, and bacteria not previously detected by cultured based techniques, such as Sphingomonas species (expressing glycolipids that can activate NKT cells), are indeed present in the lungs of a large fraction of patients with asthma. We have assembled an outstanding team of investigators, including experts in lung biology, lipid biochemistry, microbiology and immunology. Using very novel techniques, we have generated exciting preliminary data, which suggest that 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.