Lineage tracing the embryonic origins of tissue-resident macrophages

项目摘要 巨噬细胞是先天免疫系统的吞噬细胞，在宿主防御中起关键作用， 自我平衡过程和发育。过度活跃或受损的巨噬细胞活性与 许多人类疾病的病理学，包括急性和慢性感染，炎性疾病， 自身免疫性疾病和代谢紊乱，而巨噬细胞功能不全的有害影响是 在原发性免疫缺陷如慢性肉芽肿病中明显。了解如何 巨噬细胞的发育和功能是靶向其活性以获得治疗优势的关键步骤。 “原始”巨噬细胞首先出现在发育中的胚胎的原始波期间， 在组织修剪和早期先天防御中起作用。这些最初的巨噬细胞被 另一群胚胎巨噬细胞由红骨髓前体细胞（EMP）发育而来， 在造血干细胞（HSC）出现之前出现的瞬时寡能前体。它有 长期以来一直认为原始和EMP衍生的巨噬细胞被HSC衍生的巨噬细胞取代 一旦造血干细胞被确定为成熟的造血前体。然而，最近的几份报告 已经通过证明某些巨噬细胞群体存在于 永久存在于组织中，起源于出生前播种的前体。此外，这些“组织- 常驻巨噬细胞”通过自我更新重新填充自己，并且可以独立于 HSC。尽管取得了这些进展，组织驻留巨噬细胞的精确胚胎前体仍然存在 由于前体细胞之间的细胞标志物重叠和子宫内的挑战， 实验由于造血发育在脊椎动物物种之间是高度保守的， 斑马鱼模型提供了一个独特的机会来规避这些问题;斑马鱼胚胎是透明的 并在外部发育，这使得它们特别适合活体成像和谱系追踪技术。 此外，与小鼠不同，斑马鱼原始巨噬细胞、EMP和HSC在不同的时间出现， 在不同的解剖学分区中。在这项提案中，血统追踪工具，专门跟踪的命运， 原始和EMP衍生的巨噬细胞将被开发并用于比较它们在成人中的持久性。 组织中此外，我们将使用最近描述的红外激光基因在原位特异性标记单细胞 操作员（IR-LEGO）系统这项技术将使我们能够应用前所未有的水平的目标 精确地描绘出每一种前体的命运。最终，该项目将开发一个平台， 组织驻留巨噬细胞的不同起源的功能后果。

Project Summary Macrophages are phagocytes of the innate immune system that serve critical roles in host defense, homeostatic processes, and development. Overactive or impaired macrophage activity is associated with the pathology of numerous human diseases, including acute and chronic infections, inflammatory disorders, autoimmune diseases, and metabolic disorders, while the deleterious effects of macrophage insufficiency is evident in primary immune deficiencies such as chronic granulomatous disease. Understanding how macrophages develop and function is a key step toward targeting their activity for therapeutic advantage. “Primitive” macrophages first appear during the primitive wave in developing embryos, and are thought to function in the pruning of tissues and early innate defenses. These initial macrophages are reinforced by another population of embryonic macrophages that develops from erythromyeloid precursors (EMP), a transient oligopotent precursor that appears prior to the emergence of hematopoietic stem cells (HSCs). It has long been presumed that primitive and EMP-derived macrophages are replaced by HSC-derived macrophages once HSCs are established as the definitive adult hematopoietic precursor. However, several recent reports have challenged this assumption by demonstrating that certain populations of macrophages that reside permanently in tissues originate from a precursor that is seeded prior to birth. Furthermore, these “tissue- resident macrophages” repopulate themselves through self-renewal and can be maintained independently of HSCs. Despite these advancements, the precise embryonic precursor of tissue-resident macrophages remains unclear due to the overlap of cellular markers between precursor cells and the challenges of in utero experimentation. Since hematopoietic development is highly conserved between vertebrate species, the zebrafish model provides a unique opportunity to circumvent these issues; zebrafish embryos are transparent and develop externally, which makes them especially amenable live imaging and lineage tracing techniques. Furthermore, unlike in mice, zebrafish primitive macrophages, EMPs, and HSCs emerge at different times and in distinct anatomical compartments. In this proposal, lineage-tracing tools to specifically track the fates of primitive and EMP-derived macrophages will be developed and used to compare their persistence in adult tissues. In addition, we will specifically label single cells in situ using the recently described infrared laser gene operator (IR-LEGO) system. This technology will allow us to apply an unprecedented level of targeting precision to map the fate of each precursor. Ultimately, this project will develop a platform to assay potential functional consequences of the divergent origins of tissue-resident macrophages.