Endogenous glycosphingolipid antigens for NKT cells

自然杀伤T细胞(NKT)是一种NK细胞和T细胞的混合细胞类型，但只有在 抗原刺激。NKT细胞通过识别脂质配体连接天然免疫和获得性免疫 既有微生物来源，也有自身来源。内源性NKT配体，是自身的代谢产物 脂质，参与传染病、自身免疫性疾病和癌症的免疫病理。 然而，由于技术上的原因，这些内源性配体的分子鉴定一直很困难。 障碍。最近，我们发现一种抑制葡萄糖神经酰胺合成酶的药物NB-DGJ完全 取消NKT细胞的发育。更重要的是，我们鉴定了异三糖神经酰胺， 被NB-DGJ抑制的靶标糖鞘糖脂之一，作为第一个已知的天然配体 NKT细胞。然而，iGb3合酶基因敲除小鼠在NKT细胞发育和 功能，表明存在其他GSL和/或非GSL配体。持续发展的 糖脂组学分析在离子俘获质谱学技术的帮助下，增强了我们 进一步了解这些机制，并确定新的配体。 在这个项目中，我们将检验NKT细胞的至少一个内源性配体，而不是 IGb3，存在并负责NKT细胞的发育和激活。标识一个或多个 内源性配体可能为调节NKT细胞在疾病中的功能提供新的途径 例如癌症和自身免疫性疾病。本项目的具体目标是：1)确定 通过生化分级和分析确定刺激性GSL和/或非GSL抗原的身份； 利用遗传途径识别潜在的内源性NKT配体。 NKT细胞天然配体的分子鉴定不仅迫在眉睫，而且具有挑战性 在先天免疫领域的任务。尽管寻找这些配体的工作已经持续了一个多月 十年来，它们仍然难以捉摸。因此，我们选择了一种组合的生化方法 关键酶的分离/表征和基因敲除有助于实现这一研究 为成果干杯。人类基因组计划的完成与质谱学的进步 技术提供了推动脂类抗原领域向前发展的框架，并可能允许 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，这个项目将提供对细胞脂质组学研究的早期洞察，具有特定的 重点介绍糖脂的重要免疫功能。人类体内超过10%的基因 人类基因组用于脂肪代谢；因此，在这个项目中获得的知识和经验 可能会对功能脂质组学的研究产生深远的影响，这是一个重要但鲜为人知的问题 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.