Molecular studies of lipid presentation and T cell recognition of CD1c

描述（由申请人提供）：CD 1c是CD 1蛋白家族的成员，其结构与主要组织相容性复合物I类分子相似。CD 1分子已经进化出独特的脂质结合口袋（称为A'和F'），其理想地适合于通过其疏水烃尾结合多种脂质抗原。CD 1c福尔斯属于在人类中发现的CD 1分子的第1组家族;小鼠中缺乏同源物。由于我们缺乏一个易于处理的模型来探测第1组CD 1分子的功能，所以对CD 1c和识别它的T细胞的免疫功能知之甚少。我们最近的CD 1c晶体结构揭示了这个主题，揭示了这个分子的几个独特特征，赋予它结合不同抗原的能力。该结构还显示了CD 1c如何呈递结核分枝杆菌（MPM）的细胞壁脂质（疫苗开发的关键潜在靶标），并提供了关于十二聚体N-末端酰化脂肽（“lipo 12”）如何也可以被呈递的线索。然而，目前还不清楚CD 1c如何呈递其他脂质，这种复合物如何被T细胞识别，以及CD 1c特异性的T细胞库的特征是什么（以及这是否会随着不同的脂质抗原而变化）。为了解决这些问题，并更充分地了解CD 1c及其在向T细胞呈递多种脂质中的作用，我们将使用以下策略：我们的第一个目标，“表征CD 1c脂质呈递的生物物理和结构细节。重点是了解CD 1c呈递的结构特征以及内在（脂质结构）和外在（pH和分子伴侣）因素如何调节CD 1c的脂质库。我们的第二个目标是，“在分子水平上确定TCR如何识别CD 1c/脂质配体。“专注于使用结构，生物物理和功能方法来揭示TCR如何在分子水平上识别CD 1c/脂质。这是一个与全球理解T细胞识别相关的关键问题：不同的T细胞如何“看到”CD 1分子？这种识别是否像经典的TCR/MHC样？或者是否存在让人想起恒定的自然杀伤T细胞识别CD 1d的特征？目前，我们没有关于这一进程的信息。最后，我们的第三个目标，“描述识别CD 1c的T细胞的特征。“将专注于识别CD 1c应答的T细胞库，并表征这些T细胞的细胞表面标志物（共受体，记忆标志物），效应功能（细胞因子分泌和/或细胞毒性）及其TCR序列，特别是确定CDR环中是否有用于识别过程的基序。我们将探索健康和患病个体的人类谱系，并将利用人源化CD 1c小鼠模型来探索那里的T细胞谱系。目前，我们对CD 1c对人类免疫的贡献的理解还处于起步阶段，但暗示了它在病原体识别（如M。结核病已经很明显了。我们的提议将扩大我们对CD 1c脂质呈递和对其反应的T细胞的理解。

DESCRIPTION (provided by applicant): CD1c is a member of the CD1 family of proteins that are similar in structure to Major Histocompatibility Complex class I molecules. CD1 molecules have evolved unique lipid binding pockets (called A' and F') ideally suited for binding diverse lipid antigens via their hydrophobic hydrocarbon tails. CD1c falls into the Group 1 family of CD1 molecules found in humans; homologues are lacking in the mouse. Because we lack a tractable model by which to probe the function of Group 1 CD1 molecules, little is known about the immunological function of CD1c and the ¿¿ T cells that recognize it. Our recent crystal structure of CD1c shed light on this topic, revealing several unique features of this molecule that endows it with the capacity to bind diverse antigens. This structure also showed how CD1c presents a cell-wall lipid of Mycobacterium tuberculosis (MPM), a key potential target for vaccine development, and provides clues as to how a dodecameric N- terminally acylated lipopeptide ("lipo12") can also be presented. However, it is still unknown how CD1c presents other lipids, how this complex is recognized by ¿¿ T cells, and what characteristics dictate the ¿¿ T cell repertoire specific for CD1c (and whether this changes with different lipid antigens). In order to address these questions and more fully understand CD1c and its role in presenting diverse lipids to ¿¿ T cells, we will use the following strategies: our first aim, "To characterize the biophysical and structural details of CD1c lipid presentation." is focused on understanding the structural features of CD1c presentation and how intrinsic (lipid structure) and extrinsic (pH and chaperones) factors modulate CD1c's lipid repertoire. Our second aim, "To define how ¿¿ TCRs recognize CD1c/lipid ligands at the molecular level." is focused on using structural, biophysical and functional approaches to reveal how ¿¿ TCRs recognize CD1c/lipid at the molecular level. This is a key question relevant to globally understanding T cell recognition: How do diverse ¿¿ T cells "see" CD1 molecules? Is this recognition like classical ¿¿ TCR/MHC-like? Or are there features reminiscent of invariant Natural Killer T cell recognition of CD1d? Currently we have no information on this process. Finally, our third aim, "To characterize the repertoire of ¿¿ T cells that recognize CD1c." will focus on identifying the ¿¿ T cell repertoire that is CD1c responsive and to characterize these T cells for cell-surface markers (co-receptors, memory markers), effector functions (cytokine secretion and/or cytotoxicity) and the sequence of their TCRs, specifically to determine whether there are motifs in the CDR loops that are used in this recognition process. We will explore the human repertoire from health and diseased individuals and will make use of a humanized CD1c murine model to explore the T cell repertoire there. Currently our understanding of CD1c's contribution to human immunity is in its infancy, yet hints at its importance in pathogen recognition (such as M. tuberculosis) are already evident. Our proposal will expand our understanding of CD1c lipid presentation and the T cells that are reactive to it.