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，在宿主防御中发挥关键作用， 动态平衡过程和发育。巨噬细胞活性过度或受损与 许多人类疾病的病理学，包括急性和慢性感染、炎症性疾病、 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 主要表现为免疫缺陷，如慢性肉芽肿性疾病。了解如何 巨噬细胞的发育和功能是针对其活性以获得治疗优势的关键一步。 “原始”巨噬细胞首先出现在发育中的胚胎的原始波中，并被认为是 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通过 另一组胚胎巨噬细胞是从红髓系前体细胞(EMP)发育而来的 在造血干细胞(HSCs)出现之前出现的暂时性低电势前体。它有 长期以来，人们一直认为原始和EMP来源的巨噬细胞会被HSC来源的巨噬细胞取代 一旦造血干细胞被确定为明确的成人造血祖细胞。然而，最近的几篇报道 对这一假设提出了挑战，证明了居住在 永久地在组织中起源于出生前播种的前体。此外，这些“组织-- 驻留巨噬细胞“通过自我更新来重新填充自己，并且可以独立于 造血干细胞。尽管有这些进展，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记重叠和宫内移植的挑战而不清楚 实验。由于脊椎动物之间的造血发育是高度保守的， 斑马鱼模型为规避这些问题提供了一个独特的机会；斑马鱼的胚胎是透明的 并向外发展，这使得它们特别适合实时成像和血统追踪技术。 此外，与小鼠不同的是，斑马鱼原始巨噬细胞、EMPs和HSCs在不同的时间和 在不同的解剖隔间里。在这项提案中，血统追踪工具专门跟踪 将开发原始巨噬细胞和电磁脉冲来源的巨噬细胞，并用于比较它们在成人中的持久性 纸巾。此外，我们将使用最近描述的红外激光基因对单个细胞进行特定的原位标记 操作员(IR-LEGO)系统。这项技术将使我们能够应用前所未有的目标水平 精确地绘制出每个先驱的命运。最终，该项目将开发一个分析潜力的平台 组织驻留巨噬细胞不同来源的功能后果。

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.