Braking Macrophage Cell-Cell Fusion in the Foreign Body Response

由于其多功能性和可塑性，巨噬细胞有能力经历表型。 以及对微环境提示做出反应的功能变化。一个这样的变化是 某些细菌或细菌引发的细胞间融合形成多核巨细胞 寄生虫感染或植入医疗器械以引起异物反应。我们 另一些研究表明，跨膜蛋白CD13是一种多功能分子 它调节多种过程，如肿瘤细胞侵袭、免疫细胞运输、受体 介导的细胞内吞作用和肌动蛋白细胞骨架的循环和组织。在我们的 初步数据显示，尽管造血细胞的分布相对正常 骨髓和外周血中的成分，CD13KO小鼠通过 单位骨表面积破骨细胞(OC)数量增加，但骨形成正常 参数。CD13缺陷骨髓祖细胞的体外诱导 骨髓导致超融合产生多核巨细胞(MGCs)或OCS， 比野生型大得多，含有更多的细胞核 祖细胞，提示CD13是共同融合途径的组成部分 MGC和OC。我们观察到，虽然关键融合蛋白Dynamin和Dynamin的表达 DC-STAMP，通常在融合后的成熟细胞中下调，表达这些 在缺乏CD13的多核细胞中，蛋白质维持在高水平。因此，CD13作为 一种抑制常见细胞-细胞融合途径的刹车，可能成为新的治疗靶点 在异常细胞融合介导的病理条件下。在这份提案中，我们将确定 CD13依赖的机制、分子和信号通路参与细胞- 巨噬细胞融合过程中的细胞融合(目标1)和 融合封闭的抗CD13单抗作为体内外治疗药物(目的) 2)。我们将用我们广泛的野生型和CD13敲除原代细胞 小鼠和人类来源，CD13阻断或激活抗体，新的CRISPR缺失 CD13KO髓系细胞系以及共聚焦和旋转磁盘显微镜和 CD13基因敲除小鼠模型解决了这些问题。

By virtue of their versatility and plasticity, macrophages have the ability to undergo phenotypic and functional changes in response to microenvironmental cues. One such change is the formation of multinucleated giant cells via intercellular fusion triggered by certain bacterial or parasitic infections or implantation of medical devices to induce a foreign body response. We and others have shown that the transmembrane protein CD13 is a multifunctional molecule that regulates diverse processes such as tumor cell invasion, immune cell trafficking, receptor mediated endocytosis and recycling and organization of the actin cytoskeleton. In our preliminary data, we demonstrate that despite a relatively normal distribution of hematopoietic components in bone marrow and periphery, CD13KO mice have reduced bone mass with increased osteoclast (OC) numbers per bone surface area but normal bone formation parameters. In vitro induction of CD13-deficient myeloid progenitors generated from bone marrow resulted in hyperfusion to generate multinucleated giant cells (MGCs) or OCs that were considerably larger in size, contained many more nuclei than those from wild type progenitors, suggesting that CD13 is a component of common fusion pathways shared by MGC and OC. We observed that while expression of the key fusion proteins, dynamin and DC-STAMP, are typically downregulated in mature cells post-fusion, expression of these proteins is sustained at high levels in multinucleated cells lacking CD13. Thus, CD13 acts as a brake to restrain a common cell-cell fusion pathway and may be a novel therapeutic target in pathological conditions mediated by abnormal cell fusion. In this proposal, we will identify the CD13-dependent mechanisms, molecules and signaling pathways involved in cell- cell fusion in macrophages undergoing giant cell fusion (Aim 1) and the potential for fusion-blocking anti-CD13 monoclonal antibodies as therapeutics in vitro and in vivo (Aim 2). We will use our extensive panels of wild type and CD13 knock out primary cells of mouse and human origin, CD13 blocking or activating antibodies, novel CRISPR-deleted CD13KO myeloid cell lines along with confocal and spinning disk microscopy and CD13 knockout mouse models to address these questions.