Exploring the thymic origin of group 2 innate lymphoid cells

摘要 先天性淋巴样细胞（ILC）在形成先天性和适应性免疫中发挥着不同的作用。这些细胞以 异质群体及其身份受到其组织环境的影响。同样， ILC的个体发育也是复杂的。尽管ILCs被认为是由骨髓祖细胞或组织 常驻祖细胞分布在胚胎发生过程中，我们实验室的工作强烈表明， 至少ILC 2也可以在胸腺中产生，不仅来自多能祖细胞，而且来自 定向T细胞前体。我们最近使用单细胞RNA测序的数据表明， 野生型小鼠（WT）血液中富含ILC的群体的一部分来自胸腺，并且它们的 在外周组织中也可以找到等同物。因此，我们假设胸腺输出a 大量的ILC前体进入循环，其可补充ILC 2和/或其它ILC 在外周组织中处于稳态或在免疫激发时，胸腺来源的ILC可以 有不同的功能。在这项更新建议中，我们打算跟进这些令人兴奋的新发现， 确定这些胸腺源ILC前体的功能及其生物学意义。我们将进一步 表征肺和小肠中胸腺来源的ILC前体并确定其频率 在小鼠发育过程中。我们还将鉴定人血液中胸腺衍生的ILC前体，从而获得 这些细胞的临床意义的评价。然后，我们将重点学习这些功能 使用体外和体内方法，以及过继转移纯化的胸腺衍生的ILC前体， ILC前体导入缺乏ILC的Rag 2-/-Il 2g-/-小鼠。这些细胞在2型免疫中的行为 反应将被监测。最后，我们将评估WT ILC 2之间的细胞内在功能差异。 由骨髓共同淋巴祖细胞（CLP）和胸腺DN 1和DN 3 T细胞前体产生。 综上所述，本提案中概述的研究将进一步加深我们对胸腺源性ILC的理解， 将有助于建立一个关于生产和维护ILC池的新模式。因为 存在一个活跃的胸腺代表了儿童和成人之间的主要区别之一，知识 关于胸腺来源的ILC可能揭示了它们不同的免疫反应，例如在Covid-19期间的免疫反应 感染

Abstract Innate lymphoid cells (ILCs) play diverse roles in shaping innate and adaptive immunity. These cells exist as heterogeneous populations and their identities are influenced by their tissue environments. Likewise, the ontogeny of ILCs is also complex. Although ILCs are thought to arise from bone marrow progenitors or tissue resident progenitors distributed during embryogenesis, work from our laboratory strongly suggest that ILCs at least ILC2s can also be generated in the thymus, not only from multipotent progenitors but also from committed T cell precursors. Our recent data using single cell RNA sequencing suggest that a substantial fraction of the ILC-enriched population in the blood of wild type mice (WT) come from the thymus, and their equivalents can also be found in peripheral tissues. We thus hypothesize that the thymus exports a substantial amount of ILC precursors to the circulation, which may replenish ILC2s and/or other ILCs in peripheral tissues in steady-state or upon immune challenges and the thymus-derived ILCs may have distinct functions. In this renewal proposal, we intend to follow up on these new exciting findings and determine the function of these thymus-derived ILC precursors and their biological significant. We will further characterize thymus-derived ILC-precursors in the lung and small intestine and determine their frequencies during mouse development. We will also identify thymus-derived ILC precursors in human blood, thus gaining appreciation of the clinical relevance of these cells. We will then focus on learning the function of these thymus-derived ILC precursors using in vitro and in vivo approaches, as well as adoptive transfer of purified ILC precursors into Rag2-/-Il2g-/- mice which are devoid of ILCs. The behaviors of these cells in type 2 immune reactions will be monitored. Finally, we will assess the cell-intrinsic functional differences among WT ILC2s generated from bone marrow common lymphoid progenitors (CLP) and thymic DN1 and DN3 T cell precursors. Taken together, studies outlined in this proposal will further our understanding of thymus-derived ILCs, which will help establish a new paradigm regarding to the production and maintenance of ILC pools. Because the presence of an active thymus represents one of the major differences between children and adults, knowledge about thymus-derived ILCs may shed light on their different immune responses such as those during Covid-19 infection.