Role of secreted phospholipase A2 in the activation of human CD1-restricted T cells

分泌型磷脂酶 A2 在人 CD1 限制性 T 细胞激活中的作用

• 批准号: 10529317
• 负责人: Annemieke de Jong
• 金额: $ 35.64万
• 依托单位: COLUMBIA UNIVERSITY HEALTH SCIENCES
• 依托单位国家: 美国
• 财政年份: 2019
• 资助国家: 美国
• 起止时间: 2019-05-01 至 2024-11-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/10529317
• 关键词: Acute; Anti-Inflammatory Agents; Antigen Presentation; Antigen-Presenting Cells; Antigens; Arachidonic Acids; Arthritis; Asthma; Atherosclerosis; Autoantigens; Autoimmune; Binding; Biological Assay; Blood; CD1 Antigens; CD1a antigen; Cell Culture Techniques; Cell Separation; Cell membrane; Cells; Chronic; Clinical; Clonal Expansion; Complex; Cross Reactions; Eicosanoid Production; Eicosanoids; Enzymes; Fatty Acids; Flow Cytometry; Generations; Homeostasis; Homing; Human; Hydrophobicity; Immune; Immune system; Individual; Infection; Inflammation; Inflammatory; Investigation; Lecithin; Link; Lipids; Lysophosphatidylcholines; Lysophospholipids; MHC Class I Genes; MHC antigen; Membrane; Modeling; Pathogenesis; Pathway interactions; Patients; Peptides; Phenotype; Phospholipase A2; Phospholipids; Physiological; Population; Proteins; Psoriasis; Regulation; Regulatory T-Lymphocyte; Rheumatoid Arthritis; Role; Skin; Specificity; System; T cell receptor repertoire sequencing; T cell response; T-Cell Activation; T-Cell Receptor; T-Lymphocyte; T-Lymphocyte Subsets; Therapeutic; Tissues; antigen binding; autoreactive T cell; blood fractionation; immunoregulation; in vivo; insight; lipid mediator; novel; phospholipase A2 inhibitor; prevent; response; sensor; skin disorder; therapy development; tool

PROJECT SUMMARY CD1 proteins are structurally related to MHC class I, but instead of peptides, they present lipid antigens to T cells. We and others have shown that CD1-restricted T cells recognizing self-lipids are abundant in the human T cell repertoire, yet it remains unclear how the activation of these T cells is regulated in vivo. Overt reactivity to self-lipids suggests that antigenic CD1-lipid complexes must be tightly regulated in order to prevent continuous T cell stimulation. Both fatty acids and lysophosphatidylcholine (LPC) have been identified as antigens for certain human CD1-restricted T cells. These lipids are released when the enzyme phospholipase A2 (PLA2) acts on membrane phospholipids, supporting a role for PLA2 activity in the generation of CD1 self antigens. Since secreted PLA2 (sPLA2) is increased in response to tissue damage and infections, we hypothesize that sPLA2 activity in humans is a common mechanism through which the activation of CD1-restricted T cells is regulated, by temporarily increasing the availability of CD1 self-lipid antigens. This is supported by our preliminary observations that PLA2 activity on antigen presenting cells results in CD1-dependent T cell activation in healthy individuals. Furthermore, since sPLA2 levels are constitutively elevated in many chronic inflammatory conditions, including rheumatoid arthritis, asthma, atherosclerosis and psoriasis, this mechanism may underlie persistent T cell activation in these conditions through continued high levels of self lipid antigens. In this proposal we will systematically investigate the link between sPLA2 activity and activation of lipid-specific T cell populations, and characterize the human CD1-restricted T cell populations that respond to PLA2-derived phospholipid breakdown products. Using T cell cultures and a human skin explant model, we will determine if PLA2 activity induces the activation/expansion of lysophospholipid-reactive T cell populations. We will investigate the breadth of the human lysophospholipid-specific T cell repertoire, and its specificity/promiscuity. For this we use a panel of lysophospholipid-loaded CD1 tetramers, and a CD1 plate assay. Last, we will apply combined single cell TCR sequencing and functional phenotyping to CD1-LPC tetramer+ T cells isolated from healthy donors and psoriasis patients, to determine if these populations primarily have pro-inflammatory or immunoregulatory functions, and whether clonal expansions occur in the context of inflammatory skin disease. This proposal will provide insight in whether sPLA2 activity is a significant driver of human CD1-restricted T cell activation, and will elucidate the specificities and functions of the responding T cell populations. Because sPLA2 activity is central to both acute and chronic inflammation, results from this study will lead to a better understanding of a common physiological pathway through which T cells can be activated in multiple distinct inflammatory conditions, and provide novel insights in modes through which lipid-specific T cell activation may be regulated therapeutically.

项目概要 CD1 蛋白在结构上与 I 类 MHC 相关，但它们不是肽，而是向 T 呈递脂质抗原 细胞。我们和其他人已经证明，识别自身脂质的 CD1 限制性 T 细胞在人类中大量存在 T 细胞库，但仍不清楚这些 T 细胞的激活在体内是如何调节的。明显的反应 自脂质表明抗原 CD1-脂质复合物必须受到严格调节，以防止连续 T 细胞刺激。脂肪酸和溶血磷脂酰胆碱 (LPC) 均已被鉴定为某些抗原 人类 CD1 限制性 T 细胞。当磷脂酶 A2 (PLA2) 作用于 膜磷脂，在 CD1 自身抗原的生成中支持 PLA2 活性的作用。自从 分泌的 PLA2 (sPLA2) 因组织损伤和感染而增加，我们假设 sPLA2 人类的活性是调节 CD1 限制性 T 细胞活化的常见机制， 通过暂时增加 CD1 自身脂质抗原的可用性。这得到了我们初步的支持 观察到 PLA2 对抗原呈递细胞的活性导致健康人中 CD1 依赖性 T 细胞激活 个人。此外，由于 sPLA2 水平在许多慢性炎症条件下持续升高， 包括类风湿性关节炎、哮喘、动脉粥样硬化和牛皮癣，这种机制可能是持续性 T 在这些条件下，通过持续高水平的自身脂质抗原来激活细胞。在本提案中，我们将 系统地研究 sPLA2 活性与脂质特异性 T 细胞群激活之间的联系，以及 表征对 PLA2 衍生的磷脂分解做出反应的人类 CD1 限制性 T 细胞群 产品。使用 T 细胞培养物和人类皮肤外植体模型，我们将确定 PLA2 活性是否会诱导 溶血磷脂反应性 T 细胞群的激活/扩增。我们将调查人类的广度 溶血磷脂特异性 T 细胞库及其特异性/混杂性。为此，我们使用一个面板 溶血磷脂负载的 CD1 四聚体和 CD1 板测定。最后，我们将应用组合单细胞TCR 对从健康捐献者和银屑病患者中分离出的 CD1-LPC 四聚体+ T 细胞进行测序和功能表型分析 患者，以确定这些人群是否主要具有促炎或免疫调节功能，以及 克隆扩增是否发生在炎症性皮肤病的背景下。该提案将提供见解 sPLA2 活性是否是人类 CD1 限制性 T 细胞激活的重要驱动因素，并将阐明 响应 T 细胞群的特异性和功能。因为 sPLA2 活性对于急性 和慢性炎症，这项研究的结果将有助于更好地了解常见的生理学 T 细胞可以在多种不同的炎症条件下被激活的途径，并提供新的 深入了解脂质特异性 T 细胞激活的治疗调节模式。