Braking Macrophage Cell-Cell Fusion in the Foreign Body Response

由于它们的多功能性和可塑性，巨噬细胞具有进行表型分化的能力。 以及对微环境线索的功能变化。其中一个变化是 由某些细菌或细菌引起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引起异物反应。我们 其他研究表明，跨膜蛋白CD 13是一种多功能分子， 调节多种过程，如肿瘤细胞侵袭，免疫细胞运输，受体 介导的内吞作用和再循环以及肌动蛋白细胞骨架的组织。在我们 初步数据表明，尽管造血细胞分布相对正常， 在骨髓和外周中，CD 13 KO小鼠的骨量减少， 单位骨表面积破骨细胞（OC）数量增加，但骨形成正常 参数体外诱导骨来源的CD 13缺陷型髓系祖细胞 骨髓导致过度融合，产生多核巨细胞（MGCs）或OC， 与野生型相比， 祖细胞，表明CD 13是一个共同的融合途径共享的组成部分， MGC和OC。我们观察到，当关键融合蛋白发动蛋白和 DC-STAMP通常在融合后的成熟细胞中下调，这些基因的表达在融合后的成熟细胞中下调。 在缺乏CD 13的多核细胞中，蛋白质维持在高水平。因此，CD 13作为 抑制常见的细胞-细胞融合途径的制动器，可能成为新的治疗靶点 在由异常细胞融合介导的病理条件下。在本提案中，我们将确定 CD 13依赖的机制，分子和信号通路参与细胞- 巨噬细胞中发生巨细胞融合的细胞融合（Aim 1）和 融合阻断性抗CD 13单克隆抗体作为治疗剂在体外和体内（目的 2）。我们将使用我们广泛的野生型和CD 13敲除的原代细胞组， 小鼠和人来源，CD 13阻断或活化抗体，新型CRISPR缺失的 CD 13 KO髓样细胞系沿着，共聚焦和旋转圆盘显微镜， CD 13敲除小鼠模型来解决这些问题。

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.