Contribution of macrophages in the HSC niche

项目总结： 我们实验室以前的研究表明，骨髓的CD169巨噬细胞 通过调节基质细胞中CXCL12的合成来促进造血干细胞(HSC)的利基活动 它们在BM中的保留。初步结果揭示了巨噬细胞的两个新功能，即直接调节 HSC功能。首先，我们提供了巨噬细胞在基因中毒后对HSC再生至关重要的证据。 通过肠道微生物区系传递的信号调节铁的可利用性来挑战。第二，我们有 研究发现，骨髓巨噬细胞可以将关键的滞留信号传递给造血干细胞/祖细胞，这些信号赋予骨髓细胞居留的能力。 事实上，从巨噬细胞接受转移的HSCs保留在骨髓中，而只有那些 在给予G-CSF后，尚未从骨髓微环境中动员。这些结果提高了 巨噬细胞在调节HSCs、RBC中的各种功能是否具有重要的新问题 产生或清除是由相同的细胞实现的，或者是骨髓巨噬细胞是否有专门的 功能。在这项提案中，我们将探讨巨噬细胞可以直接对生态位做出贡献的假设。 通过调节HSCs的再生和从骨髓中排出的能力来调节活动。在具体目标1中，我们将 研究巨噬细胞如何与微生物群相互作用以促进HSC再生。我们将使用基因 操纵HSC和巨噬细胞中铁转运途径的模型以剖析铁的机制 在造血再生过程中提供给造血干细胞/祖细胞。我们还将评估骨髓巨噬细胞如何 可以感知微生物区系发出的信号。在具体目标2中，我们将研究通过哪些机制 巨噬细胞指定骨髓驻留。我们将评估连接蛋白在细胞间通讯中的作用 使用CRISPR/Cas9介导的靶向，并确定巨噬细胞增多作为转移机制的作用。具体而言 目的3，我们将进一步定义骨髓驻留的巨噬细胞群。我们将评估空间 免疫荧光法检测巨噬细胞与血管结构、造血干细胞和红细胞的关系 成像。我们将使用基因技术研究BM驻留巨噬细胞的来源(胚胎或造血) 追踪方法。这些研究将揭示一个被低估的组成部分的关键功能 HSC利基和发现血液疾病的新治疗方法。

PROJECT SUMMARY: Previous studies from our laboratory have suggested that CD169+ macrophages of the bone marrow (BM) contribute to the hematopoietic stem cell (HSC) niche activity by regulating CXCL12 synthesis in stromal cells and their retention in the BM. Preliminary results reveal two novel functions of macrophages in directly regulating the HSC function. First, we provide evidence that macrophages are critical for HSC regeneration after genotoxic challenge via the regulation of iron availability mediated by signals from the gut microbiota. Second, we have found that BM macrophages can transfer to HSCs/progenitors key retention signals that confer residence in BM. Indeed, HSCs that have received the transfer from macrophages are retained in the BM, whereas only those that have not are mobilized from the BM microenvironment following G-CSF administration. These results raise important new questions as to whether the various functions of macrophages in regulating HSCs, RBC production, or clearance are achieved by the same cells or whether the BM macrophages have specialized functions. In this proposal, we will explore the hypothesis that macrophage can directly contribute to niche activities by regulating HSCs’ ability to regenerate and to egress from the BM. In Specific Aim 1, we will investigate how macrophages interact with the microbiota to promote HSC regeneration. We will use genetic models to manipulate iron delivery pathways in HSCs and macrophages to dissect the mechanism by which iron is supplied to HSCs/progenitors during hematopoietic regeneration. We will also evaluate how BM macrophages can sense signals from the microbiota. In Specific Aim 2, we will investigate the mechanisms by which macrophages assign bone marrow residence. We will assess the role of connexins in the cell-cell communication using CRISPR/Cas9-mediated targeting and determine the role of trogocytosis as transfer mechanism. In Specific Aim 3, we will further define the bone marrow-resident macrophage population. We will evaluate the spatial relationship of these macrophages with vascular structures, HSCs and erythroblasts using immunofluorescence imaging. We will investigate the origin (embryonic or hematopoietic) of BM- resident macrophages using genetic tracing methods. These studies will shed light into the critical functions of an under-appreciated component of the HSC niche and uncover new therapeutic approaches for blood disorders.