Role of GM-CSF in Alveolar Macrophage Self-Renewal

摘要 肺泡巨噬细胞（Alveolar macrophages，AM）是一种自我更新的细胞群，不需要补充 健康成年小鼠的肺外来源;然而，所涉及的机制以及补充是否 通过刺激祖细胞或成熟AM的增殖而发生。我们报告说， 粒细胞/巨噬细胞集落刺激因子（GM-CSF）控制巨噬细胞反式 植入肺部（通过相互反馈回路）以及内源性AM。我的初步数据显示， GM-CSF是AM线粒体周转、完整性和功能的关键调节剂，并且是脂肪酸氧化所必需的。 衍生能源的生产，对细胞增殖至关重要的过程。先前在白血病细胞系（TF-1）中的研究表明， GM-CSF对巨噬细胞的多效性作用可能是由双相的、配体浓度依赖性受体介导的 信令，即，低水平的GM-CSF促进存活和分化（但不促进增殖），而高水平的GM-CSF也刺激细胞增殖。 细胞增殖。我们的长期目标是确定负责AM自我更新的机制。这里的目标 目的是阐明GM-CSF调节线粒体稳态控制AM自我更新的机制。岑 假设：AM是由GM-CSF阈值触发/浓度驱动的稳态自我更新维持的。 成熟（长寿）AM（非祖细胞）的依赖性、小生境限制性增殖。理由：这一假设是错误的。 基于我的报告和初步数据，证实GM-CSF缺乏导致线粒体减少， 代谢和完整性，尽管增加线粒体质量。方法：我将利用互补的遗传和phar- 宏观工具、体内和离体研究（使用分离的AM）以及途径特异性抑制剂来追求两种特异性 目的：1）AM更新的个体发生和转录调控，2）GM-CSF调节线粒体代谢的作用 在上午更新。预期的结果将为GM-CSF调控AM的细胞和分子机制提供信息 群体大小，并将为开发新的治疗策略来调节AM群体大小奠定基础。 在我看来，拟议的研究是创新的，因为它挑战了以前广泛持有的AM概念， 从循环单核细胞中补充的短寿命的非分裂细胞（由M-CSF调节）-而不是假设AM 群体大小是通过GM-CSF阈值触发/浓度释放介导的稳态自我更新来维持的。 成熟（长寿）AM的悬垂、小生境限制性增殖。我的新的初步数据确定了GM-CSF依赖 线粒体稳态的调节作为AM自我更新的分子机制。此外，利用小说 小鼠模型和新的方法学将能够确定GM-CSF如何调节线粒体内稳态， sis调节AM增殖，并将识别负责长时间增殖的调节基因及其下游靶点。 定期维护AM。拟议的研究是重要的，因为它将推进我们的知识的关键肺- 通过告知GM-CSF调节endog的长期维持的机制， 静脉和移植的AM，并告知我们的治疗作用机制的PMT，一种新的细胞疗法在发展中， 治疗遗传性肺泡蛋白沉积症和其他潜在肺部疾病的患者。

ABSTRACT Alveolar macrophages (AMs) are believed to be a self-renewing cell population without a requirement of replenishment from extra-pulmonary sources in healthy adult mice; however, the mechanism(s) involved and whether replenishment occurs by stimulating the proliferation of progenitors or mature AMs are not known. We reported that lung levels of granulocyte/macrophage-colony stimulating factor (GM-CSF) control long-term maintenance of macrophages trans- planted into the lungs (via a reciprocal feedback loop) as well as endogenous AMs. My preliminary data demonstrate that GM-CSF is a critical regulator of AM mitochondrial turnover, integrity and functions and is required for fatty acid oxidation- derived energy production, processes vital to cell proliferation. Prior studies in a leukemia cell line (TF-1) suggest the pleotropic effects of GM-CSF on macrophages may be mediated by biphasic, ligand concentration-dependent receptor signaling, i.e., low levels of GM-CSF promote survival and differentiation (but not proliferation) while high levels also stim- ulate proliferation. Our long-term goal is to determine mechanisms responsible for AM self-renewal. The objective here is to elucidate the mechanism by which GM-CSF regulation of mitochondrial homeostasis controls AM self-renewal. Cen- tral Hypothesis: AMs are maintained by homeostatic self-renewal driven by GM-CSF threshold-triggered/concentration- dependent, niche-limited proliferation of mature (long-lived) AMs (not progenitors). Rationale: This hypothesis was de- veloped based on my reported and preliminary data demonstrating GM-CSF deficiency results in reduced mitochondrial metabolism and integrity despite increased mitochondrial mass. Approach: I will utilize complementary genetic and phar- macologic tools, in vivo and ex vivo studies (with isolated AMs), and pathway-specific inhibitors to pursue two Specific Aims: 1) Ontogeny and transcriptional control of AM renewal, and 2) Role of GM-CSF regulated mitochondrial metabolism in AM renewal. The expected results will inform cellular and molecular mechanism(s) by which GM-CSF regulates AM population size and will lay the foundation for developing novel therapeutic strategies to modulate AM population size. The proposed research is innovative, in my opinion, because it challenges the previously widely-held concept of AMs as short-lived, non-dividing cells replenished from circulating monocytes (regulated by M-CSF) – and instead posits that AM population size is maintained by homeostatic self-renewal mediated by GM-CSF threshold-triggered/concentration-de- pendent, niche-limited proliferation of mature (long-lived) AMs. My novel preliminary data identified GM-CSF dependent regulation of mitochondrial homeostasis as a molecular mechanism for AM self-renewal. In addition, utilization of novel mouse models and novel methodologies will enable determination of how GM-CSF regulation of mitochondrial homeosta- sis regulates AM proliferation and will identify the regulatory genes and their downstream targets responsible for long- term maintenance of AMs. The proposed research is significant because it will advance our knowledge of a critical pulmo- nary hormone (GM-CSF) by informing the mechanism(s) by which GM-CSF regulates the long-term maintenance of endog- enous and transplanted AMs and inform us on the therapeutic mechanism of action of PMT, a novel cell therapy in devel- opment to treat patients with hereditary pulmonary alveolar proteinosis and potentially other lung diseases.