T-Cell response to CD1-restricted lipids in Tuberculosis

描述（由申请人提供）：结核分枝杆菌已感染18亿人，根据其作为细胞内病原体在人体组织中持续存在的能力，每年造成200万至300万人死亡。宿主对分枝杆菌感染的反应主要依赖于T细胞，直到最近，人们还认为T细胞仅由与MHC I类和II类蛋白结合的肽抗原激活。CD1抗原呈递分子的发现显示了朗格汉斯细胞和树突状细胞是如何通过呈递脂质抗原来激活T细胞的，这些脂质抗原包括单菌糖酸盐（Science 278，第283页）、甘露糖基磷酸基酮（Nature 404，第884页）和类粘菌素脂肽（Science 303，第527页）。本研究旨在利用高效液相色谱法从结核分枝杆菌和麻风分枝杆菌细胞壁中分离免疫优势抗原，并利用碰撞诱导解离质谱、核磁共振和x射线晶体学测定其结构。由于分枝杆菌在适应细胞内生长的过程中会重塑其细胞壁并改变其抗原谱，因此抗原发现工作将集中在直接从哺乳动物组织中分离的致病性分枝杆菌和基因修饰的结核分枝杆菌上，这些分枝杆菌缺乏从宿主组织中清除铁所需的酶。通过细胞因子捕获ELISA、细胞表面细胞因子捕获免疫荧光和脂质负载CD1四聚体染色对结核病患者T细胞前体频率进行体外分析，研究每种脂质抗原的免疫原性。通过测量记忆反应和CD1限制性T细胞库中脂质抗原特异性的复杂性，这些研究将为CD1在人类先天或获得性免疫反应中是否起作用的基本问题提供见解。此外，抗原脂质精确分子结构的鉴定为麻风病、结核病和耐多药结核病提供了全新的、不受mhc限制的免疫调节药物和疫苗的前景。

DESCRIPTION (provided by applicant): M. tuberculosis has infected 1.8 billion humans and accounts for 2 to 3 million deaths annually based on its ability to persist as an intracellular pathogen in human tissues. The host response to mycobacterial infection depends crucially on T cells, which until recently, were thought to be activated solely by peptide antigens bound to MHC class I and II proteins. The discovery of CD1 antigen presenting molecules shows how Langerhans cells and dendritic cells can activate T cells by presenting lipid antigens, including glucose monomycolate (Science 278, p. 283), mannosyl phosphomycoketides (Nature 404, p.884) and mycobactin like lipopeptides (Science 303, p. 527). This proposal aims to use high performance liquid chromatography to isolate immunodominant antigens from the M. tuberculosis and M. leprae cell walls and then determine their structures using collision induced dissociation mass spectrometry, nuclear magnetic resonance and Xray crystallography. Because mycobacteria remodel their cell walls and alter their antigen profiles during adaptation to intracellular growth, antigen discovery efforts will focus on pathogenic mycobacteria isolated directly from mammalian tissues and genetically modified M. tuberculosis that are deficient in the enzymes necessary for iron-scavenging from host tissues. The immunogenicity of each lipid antigen will be investigated by ex vivo analysis of T cell precursor frequencies in tuberculosis patients as measured by cytokine-capture ELISA, cell surface cytokine-capture immunofluorescence and staining with lipid-loaded CD1 tetramers. By measuring memory responses and the complexity of lipid antigen specificities in the CD 1-restricted T cell repertoire, these studies will provide insight into the basic question of whether CD1 functions in the innate or acquired immune responses in humans. In addition, identification of the precise molecular structures of antigenic lipids offers the prospect of fundamentally novel, MHC-unrestricted immunodulatory drugs and vaccines against leprosy, tuberculosis and multi-drug resistant tuberculosis.