Role of GM-CSF in Alveolar Macrophage Self-Renewal

摘要 肺泡巨噬细胞(AM)被认为是一种自我更新的细胞群，不需要补充。 来自健康成年小鼠的肺外来源；然而，其机制(S)涉及以及是否补充 通过刺激祖细胞或成熟AM的增殖而发生，目前尚不清楚。我们报告了肺部的水平 粒细胞/巨噬细胞集落刺激因子控制巨噬细胞的长期维持 植入肺部(通过一个相互的反馈环)以及内源性AM。我的初步数据表明 GM-CSF是AM线粒体周转、完整性和功能的关键调节因子，也是脂肪酸氧化所必需的。 衍生能量生产，对细胞增殖至关重要的过程。先前对白血病细胞系(TF-1)的研究表明 GM-CSF对巨噬细胞的促增殖作用可能是通过双相配体浓度依赖性受体介导的 信号，即低水平的GM-CSF促进生存和分化(但不是增殖)，而高水平也刺激 脐带血增殖。我们的长期目标是确定AM自我更新的机制。这里的目标是 目的是阐明GM-CSF调节线粒体稳态控制AM自我更新的机制。CEN- TRAL假说：AM由GM-CSF阈值触发/浓度-驱动的动态平衡自我更新维持 依赖、利基有限的成熟(长寿命)AM(不是祖细胞)的增殖。基本原理：这一假设是不成立的 基于我报告的和初步数据显示GM-CSF缺乏会导致线粒体减少 新陈代谢和完整性，尽管线粒体质量增加。方法：我将利用互补的遗传和药物- 马克学工具，体内和体外研究(与分离的AM)，以及途径特定的抑制剂，以追求两个特定的 目的：1)AM更新的个体发育和转录调控；2)GM-CSF调节线粒体代谢的作用 在AM更新中。预期结果将揭示GM-CSF调节AM的细胞和分子机制(S) 并将为开发调节AM种群大小的新治疗策略奠定基础。 在我看来，这项拟议的研究是创新的，因为它挑战了以前广泛持有的AM的概念，如 从循环单核细胞(受M-CSF调节)补充的短暂的、未分裂的细胞-相反，假设AM 种群大小由GM-CSF阈值触发/浓度降低介导的动态平衡自我更新来维持 成熟(长寿命)AM的悬垂、利基有限的增殖。我的新的初步数据确定了GM-CSF依赖 调节线粒体内稳态作为AM自我更新的分子机制。此外，小说的利用 小鼠模型和新的方法将能够确定GM-CSF是如何调节线粒体同源异位体的。 SIS调节AM的增殖，并将确定调控基因及其下游靶点，负责长时间的 空管的定期维护。这项拟议的研究具有重要意义，因为它将促进我们对一种关键脉冲的认识-- 通过告知GM-CSF调节内分泌长期维持的机制(S)来实现。 并对新型细胞疗法PMT的作用机制进行了探讨。 选择治疗遗传性肺泡蛋白沉积症和潜在的其他肺部疾病。

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.