Distinct contributions of CCR4 versus CCR7 to thymocyte localization and central tolerance

项目摘要 一些COVID-19患者表现良好，出现无症状或轻度疾病，而高达20%的患者 严重的症状可能致命。最近的研究表明，炎症细胞因子升高， 严重疾病患者的T细胞数量，表明免疫反应的变化可能是 疾病结果的差异。然而，对SARS的保护性免疫应答与病理性免疫应答的特征- CoV-2还没有得到很好的理解。此外，儿童往往经历较轻的症状，而老年人 个体更容易患上严重的疾病，但尚不清楚这是否是年龄相关的功能， 免疫反应的差异。在目标1中，我们提出进行配对单细胞转录组学， 蛋白质组学和TCR库测序的纵向血液样本，从COVID-19患者的不同 年龄和疾病严重程度，以全面描绘SARS免疫反应的轨迹- CoV-2和识别与疾病严重程度和年龄相关的候选免疫特征。候选 将在更大的患者队列中测试和完善签名。目前的疫苗工作集中在激发 针对SARS-CoV-2的中和抗体。需要CD 4 + T细胞应答来激活B细胞以产生 中和抗体和支持CD 8 + T细胞的分化，这可以促进病毒清除， 保持免疫记忆。然而，激活保护性T细胞应答的病毒表位仍然存在， 未知在目标2中，我们将激活来自纵向患者样本的T细胞，用于单细胞分析， 目的1与重叠肽的“大池”，跨越单个SARS-CoV-2抗原。活化的T细胞 将进行单细胞多组学分析，使我们能够确定克隆的TCR序列， 每种病毒蛋白质。对目标1的数据集进行回顾性分析将使我们能够遵循自然发展 以评估疾病过程中的频率和分化。使用这些 数据，我们将确定哪些病毒抗原在效应和记忆阶段激活特定的T细胞克隆 与每个年龄段的有利结果相关，为疫苗设计提供信息。增加的发病率 自身免疫综合征，如儿童患者中报告的川崎病，表明SARS- CoV-2可能会诱导自身免疫;相反，自身免疫综合征患者可能更容易感染CoV-2。 由于免疫失调而导致的严重疾病。在目标3中，我们将探索这两种可能性。具体来说，我们将 回顾性地确定自身免疫性是否使患者易患严重疾病， 对SARS-CoV-2抗原有更多的炎性T细胞反应。我们还将评估自身抗原 与SARS-CoV-2肽序列高度相似的肽在COVID-19中激活更高频率的T细胞 患者与未感染的对照组，我们将确定COVID-19患者是否会产生自身抗体。这些 研究将确定每个年龄的疾病严重程度的特异性免疫相关性以将患者分成风险组， 为疫苗设计提供信息，并测试自身免疫与COVID-19之间的联系，以提供知情的临床护理。

PROJECT ABSTRACT Some COVID-19 patients fare well, experiencing asymptomatic or mild disease, while up to 20% of patients have severe symptoms that can be fatal. Recent studies reveal elevated inflammatory cytokines and a reduced number of T cells in patients with severe disease, indicating that variation in immune responses may underlie differences in disease outcomes. However, features of protective versus pathologic immune responses to SARS- CoV-2 are not well understood. Furthermore, children tend to experience milder symptoms, while elderly individuals are more susceptible to severe disease, but it is not known if this is a function of age-associated differences in immune responses. In Aim 1, we propose to carry out paired single-cell transcriptomics, proteomics, and TCR repertoire sequencing of longitudinal blood samples from COVID-19 patients of different ages and disease severities in order to comprehensively profile the trajectory of immune responses to SARS- CoV-2 and identify candidate immune signatures that correlate with disease severity and age. Candidate signatures will be tested and refined in a larger patient cohort. Current vaccine efforts are focused on eliciting neutralizing antibodies against SARS-CoV-2. CD4+ T-cell responses are required to activate B cells to produce neutralizing antibodies and to support differentiation of CD8+ T cells, which can promote viral clearance and maintain immunologic memory. However, viral epitopes that activate protective T-cell responses remain unknown. In Aim 2, we will activate T cells from the longitudinal patient samples used for single-cell profiling in Aim 1 with “megapools” of overlapping peptides, spanning individual SARS-CoV-2 antigens. Activated T cells will be subjected to single-cell multi-omics analysis, allowing us to identify TCR sequences of clones that respond to each viral protein. Retrospective analysis of datasets from Aim 1 will enable us to follow the natural progression of these individual clones to evaluate frequencies and differentiation over the course of disease. Using these data, we will determine which viral antigens activate specific T-cell clones during effector and memory phases that correlate with favorable outcomes at each age, informing vaccine design. The increased incidence in autoimmune syndromes, such as the Kawasaki-like disease reported in pediatric patients, suggests that SARS- CoV-2 may induce autoimmunity; conversely, patients with autoimmune syndromes may be more susceptible to severe disease due to immune dysregulation. In Aim 3, we will explore both possibilities. Specifically, we will retrospectively determine if autoimmunity predisposes patients to severe disease and if autoimmune patients have more inflammatory T cell responses to SARS-CoV-2 antigens. We will also evaluate whether autoantigens with high sequence similarity to SARS-CoV-2 peptides activate a higher frequency of T cells in COVID-19 patients versus uninfected controls, and we will determine if COVID-19 patients develop autoantibodies. These studies will identify specific immune correlates of disease severity at each age to stratify patients into risk groups, inform vaccine design, and test links between autoimmunity and COVID-19 for informed clinical care.