The Case of the Missing Macrophages: Investigating the role of NKR-P1B:Clr-b self-recognition on tissue-resident myeloid cells.

先天免疫细胞功能通过复杂的模式识别受体系统进行调节。调节先天免疫反应的受体系统的一个例子是 C 型凝集素样受体的 NKR-P1 家族及其结合配体，即表面蛋白的 C 型凝集素相关 (Clr) 家族。 NKR-P1B 是该受体家族的抑制性成员，可识别 Clr-b，并在自然杀伤细胞上表达。使用缺乏 NKR-P1B 表达的转基因小鼠，我们观察到肺泡巨噬细胞 (AM) 数量明显受损，这是一种完全意想不到的表型。我们还发现 NKR-P1B 在 AM 上表达。我们现在寻求了解 NKR-P1B:Clr-b 识别系统如何调节肺驻留骨髓免疫细胞的发育和功能。我们提出以下两个目标：***1．了解 NKR-P1B 表达对 AM 和 DC 的影响。我们将全面描述野生型和 NKR-P1B 缺陷型肺驻留 AM 和树突状细胞 (DC) 之间的功能和表型差异。使用共聚焦显微镜，我们将分析不同年龄小鼠的肺部以确定 AM 分布和表型。我们将在 NKR-P1B 交联抗体存在的情况下进行多种功能测定，包括细胞因子释放、吞噬作用和抗原呈递测定，以模拟 NKR-P1B 结合对正常骨髓细胞功能的影响。最后，使用骨髓嵌合体在野生型环境中研究 NKR-P1B 缺陷的骨髓细胞，反之亦然，我们将研究 NKR-P1B 对骨髓细胞群的影响是细胞内在的还是外在的。***2。探索 NKR-P1B 对 AM 和 DC 发挥作用的机制。我们观察到 NKR-P1B 缺陷 AM 代谢过程受损的证据。我们将比较 WT 和 NKR-P1B 缺陷 AM 的代谢特征，以及通过 RNA 序列 (RNAseq) 分析获得的转录组，以确定差异表达的基因以及所涉及的细胞和代谢途径。我们还将使用邻近生物素化 BioID 系统研究巨噬细胞中 NKR-P1B 相互作用和细胞信号传导伙伴。***了解骨髓免疫细胞的发育和功能可以增强我们对细胞的总体理解。我们偶然发现了肺泡巨噬细胞生物学中一个以前未被重视且显然至关重要的组成部分，我们希望探索这些细胞中 NKR-P1B:Clr-b 相互作用的总体作用和特定信号传导途径的参与将为我们提供有关骨髓细胞发育和功能的基本教训。

Innate immune cell functions are regulated through sophisticated systems of pattern-recognition receptors. One example of a receptor system that regulates innate immune responses is the NKR-P1 family of C-type lectin-like receptors, and its binding ligands, the C-type lectin-related (Clr) family of surface proteins. NKR-P1B is an inhibitory member of this receptor family, which recognizes Clr-b, and is expressed on natural killer cells. Using genetically modified mice lacking NKR-P1B expression, we have observed a marked impairment in lung alveolar macrophage (AM) numbers, a completely unexpected phenotype. We have also found the NKR-P1B is expressed on AMs. We now seek to understand how NKR-P1B:Clr-b recognition system regulates lung-resident myeloid immune cell development and function. We have proposed the follow two objectives:***1. Discover the impact of NKR-P1B expression on AMs and DCs. We will fully characterize the functional and phenotypic differences between wild-type and NKR-P1B-deficient lung-resident AM and dendritic cells (DC). Using confocal microscopy, we will analyze lungs of mice at various ages to determine AM distribution and phenotype. We will perform several functional assays, including cytokine release, phagocytosis, and antigen-presenting assays in the presence of NKR-P1B cross-linking antibodies to simulate the effects of NKR-P1B engagement on normal myeloid cell function. Finally, using bone-marrow chimeras to study NKR-P1B-deficient myeloid cells in wild-type environments and vice versa, we will investigate whether NKR-P1B effects on the myeloid cell populations are cell-intrinsic or extrinsic.***2. Discover the mechanism through which NKR-P1B exerts its effects on AMs and DCs. We have observed evidence for impaired metabolic processing in NKR-P1B-deficient AMs. We will compare the metabolic profiles of WT and NKR-P1B-deficient AMs, as well as their transcriptomes obtained by RNA sequence (RNAseq) analysis to determine differentially expressed genes, and the cellular and metabolic pathways that are involved. We will also investigate NKR-P1B interacting and cell signaling partners in macrophages using the proximity-biotinylation BioID system.***Understanding myeloid immune cell development and function strengthens our understanding of cells in general. We have fortuitously stumbled into a previously unappreciatedand apparently criticalcomponent of alveolar macrophage biology, and it is our hope that exploring the involvementboth overall role and specific signaling pathwaysof NKR-P1B:Clr-b interactions in these cells will teach us fundamental lessons about myeloid cell development and function.