Endogenous glycosphingolipid antigens for NKT cells

自然杀伤T细胞（NKT）是NK细胞和T细胞的杂交细胞类型，但仅由NK细胞激活。 抗原刺激NKT细胞通过识别脂质配体连接先天免疫和适应性免疫 来自微生物和自身。内源性NKT配体，其是自身代谢产物， 脂质参与感染性疾病、自身免疫性疾病和癌症的免疫病理学。 然而，由于技术上的限制，这些内源性配体的分子鉴定一直是困难的。 隔栏.最近，我们发现NB-DGJ，一种抑制葡萄糖神经酰胺合成酶的药物， 抑制了NKT细胞的发育。更重要的是，我们发现了异三己糖神经酰胺， NB-DGJ抑制的靶鞘糖脂之一，作为第一个已知的天然配体， NKT细胞。然而，iGb 3合酶敲除小鼠在NKT细胞发育中没有表现出缺陷， 功能，表明存在其他GSL和/或非GSL配体。继续发展 糖脂组学分析，离子阱质谱技术的辅助下，提高了我们的能力， 进一步了解这些机制并识别新的配体。 在这个项目中，我们将测试的假设，至少有一个内源性配体的NKT细胞，除了 iGb 3存在并负责NKT细胞的发育和活化。识别一个或多 内源性配体可能允许新的方法来调节疾病中NKT细胞的功能 例如癌症和自身免疫性疾病。本项目的具体目标是：1）确定 通过生物化学分级分离和分析鉴定刺激性GSL和/或非GSL抗原; 2） 利用遗传途径鉴定潜在的内源性NKT配体。 NKT细胞天然配体的分子鉴定不仅是一个迫切的问题，也是一个挑战性的问题。 先天免疫领域的任务。尽管对这些配体的研究已经持续了一个多世纪， 十年来，他们仍然难以捉摸。因此，我们选择了一种生物化学和 关键酶的分离/表征和遗传敲除，以帮助实现这一搜索 结出硕果人类基因组计划的完成与质谱技术的发展 该技术提供了将脂质抗原领域向前推进的框架，并潜在地允许 确定一些最复杂的免疫相关疾病的新治疗方法。 更重要的是，该项目将为细胞脂质组学研究提供早期见解， 重点介绍糖脂的重要免疫功能。超过10%的基因在 人类基因组用于脂质代谢;因此，在该项目中获得知识和经验 可能对功能性脂质组学的研究产生深远的影响， 与蛋白质组学和基因组学相比。

Natural Killer T cells (NKT) are a hybrid cell type of NK cells and T cells, but are activated only by antigenic stimulation. NKT cells bridge innate and adaptive immunity through recognition of lipid ligands from both microbial and self origins. Endogenous NKT ligands, which are metabolism products of self lipids, are involved in immuno-pathology of infectious diseases, auto-immune diseases and cancer. However, molecular identification of these endogenous ligands has been difficult due to technical barriers. Recently, we found that NB-DGJ, a drug which inhibits glucosylceramide synthase, completely abolishes the development of NKT cells. More importantly, we identified isoglobotrihexosylceramide, one of the target glycosphingolipids being inhibited by NB-DGJ, as the first known natural ligand for NKT cells. However, iGb3 synthase knockout mice showed no defect in NKT cell development and function, indicating that other GSL and/or non-GSL ligands exist. Continued development of glycolipidomics assays, assisted by ion trap mass spectrometry technology, enhances our ability to further understand these mechanisms and identify new ligands. In this project, we will test the hypothesis that at least one endogenous ligand of NKT cells, other than iGb3, exists and is responsible for the development and activation of NKT cells. Identifying one or more endogenous ligands may permit new approaches to regulating the function of NKT cells in disease settings such as cancer and autoimmune diseases. The specific aims of this project are: 1) Determine the identities of stimulatory GSL and/or non-GSL antigens by biochemical fractionation and analysis; 2) Utilize the genetic pathways to identify potential endogenous NKT ligands. The molecular identification of natural ligands for NKT cells is not only an urgent, but also a challenging task in the field of innate immunity. Although the search for these ligands has lasted more than a decade, they remain elusive. We therefore have chosen a combined approach of biochemical fractionation/characterization and genetic knockdown of key enzymes to help bring this search to fruition. The completion of human genome project and the advancement of mass spectrometry technology provide the framework to move the field of lipid antigens forward and potentially permit the identification of new therapeutic approaches to some of the most complex immune-related diseases. More important, this project will provide early insights into cellular lipidomics studies, with a specific focus on the important immunological functions of glycolipids. More than 10% of the genes in the human genome are used for lipid metabolism; thus, knowledge and experience gained in this project may have profound implications on studies of functional lipidomics, an important but little-understood area compared with proteomics and genomics.