Exploring the thymic origin of group 2 innate lymphoid cells

摘要 先天淋巴样细胞(ILCs)在形成先天免疫和获得性免疫中发挥着不同的作用。这些单元格以 异质种群及其身份受其组织环境的影响。同样， ILC的个体发育也是复杂的。尽管ILC被认为起源于骨髓祖细胞或组织 在胚胎发育过程中分布的常驻祖细胞，我们实验室的工作强烈表明ILCs在 最少的ILC2也可以在胸腺中产生，不仅来自多能祖细胞，也来自 承诺的T细胞前体。我们最近使用单细胞RNA测序的数据表明，大量的 野生型小鼠(WT)血液中ILC富集群的一部分来自胸腺，他们的 在外周组织中也可以找到等价物。因此，我们假设胸腺输出一种 大量ILC前体进入循环，可补充ILC2和/或其他ILC 在处于稳定状态或免疫挑战的外周组织中，胸腺来源的ILCs可能 有不同的功能。在这项更新建议中，我们打算跟进这些令人振奋的新发现，并 确定这些胸腺来源的ILC前体的功能及其生物学意义。我们将进一步 肺和小肠中胸腺来源的ILC前体的特征及其频率的测定 在老鼠发育过程中。我们还将在人类血液中鉴定胸腺来源的ILC前体，从而获得 对这些细胞的临床相关性的评价。然后我们将重点学习这些组件的功能 使用体外和体内方法的胸腺来源的ILC前体以及过继转移纯化的 ILC前体转化为缺失ILC的Rag2-/-IL2G-/-小鼠。这些细胞在2型免疫中的行为 人们的反应将受到监控。最后，我们将评估WT ILC2之间的细胞固有功能差异 从骨髓共同淋巴祖细胞(CLP)和胸腺DN1和DN3 T细胞前体产生。 综上所述，这项建议中概述的研究将进一步加深我们对胸腺来源的ILCs的理解，它 将有助于建立关于生产和维护ILC池的新范例。因为 活跃胸腺的存在代表了儿童和成人的主要区别之一，即知识 关于胸腺来源的ILC可能有助于揭示它们的不同免疫反应，例如新冠肺炎期间的免疫反应 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.