Role of GM-CSF in Myeloid Cell Function and Innate Immunity

描述(申请人提供)：肺泡蛋白沉积症(PAP)是一种以肺泡巨噬细胞(AM)和肺泡内表面活性物质积聚为特征的综合征，导致呼吸衰竭和感染死亡率增加。在近40年的时间里，唯一可用的治疗方法是全肺灌洗，这是一种在少数几个中心进行的高度侵入性的手术，其中一只肺被机械通风，另一只肺被反复注入生理盐水，并对胸部进行大力冲击，以物理上清除表面活性物质。在GM-CSF-/-小鼠中发现PAP之前，由于缺乏对PAP的致病认识，药物治疗没有取得任何进展，这一发现改变了我们对GM-CSF生物学作用的概念，并导致了PAP的新诊断和治疗。我的实验室对我们理解GM-CSF对表面活性物质的动态平衡、AM个体发育、中性粒细胞和AM功能以及先天免疫至关重要，并且在大约90%的患者中，PAP是由高水平的GM-CSF自身抗体(GMAbs)引起的。现有证据表明，GM-CSF通过转录因子PU.1和PPAR？调节表面活性物质的动态平衡。通过刺激脂质转运蛋白Abcg1的表达：在GM-CSF缺陷小鼠和PAP患者中，这三种细胞都缺乏AM。尽管如此，关于PAP的自然历史，2)GM-CSF信号丢失导致PAP的机制，以及3)PU.1和PPAR3在GM-CSF调节AM表面活性物质清除和免疫功能的机制中的作用和关系，仍然存在疑问。我们将使用我们的新的自身免疫性PAP、AM细胞系和PAP生物标志物的灵长类动物模型、现有的遗传性PAP的小鼠模型以及自身免疫和遗传性PAP患者来检验我们的中心假设：PAP是由AM分泌的依赖于中性脂肪的GM-CSF、PU.1、PPAR3、Abcg1的减少引起的，这削弱了他们清除表面活性物质的能力。这一假说将在3个具体目标中阐述，重点是GM-CSF对髓系细胞的调节。在目标1中，我们将确定自身免疫性PAP的自然病程、GMAb的临界阈值以及它们对灵长类动物模型和PAP患者髓系免疫功能的影响。在目的2中，将通过慢病毒介导的巨噬细胞在遗传性PAP小鼠或人的巨噬细胞中的表达，以及通过将Abcg1转导的骨髓移植到CSF2RB-/-小鼠体内，来评估PU.1、PPARβ和Abcg1在CSF2RA或B突变引起的遗传性PAP中的作用。在目标3中，我们将确定GM-CSF是否通过PU.1依赖的PPAR调节AM的表面活性物质清除和免疫功能？使用不自发表达PU1或对GM-CSF也有反应的新型AM细胞株。在我们的灵长类动物模型中，GM-CSF在AM中调节的转录程序将在没有表面活性物质二次影响的情况下进行体内检测。我们将确定PPAR是否？激动剂吡格列酮在体外恢复患有PAP的小鼠和人类细胞中AM表面活性物质的清除，并在体内利用CSF2RB-/-小鼠恢复AM表面活性物质清除。预期的结果对PAP的发病机制和治疗、表面活性物质稳态和GMAb治疗常见炎症性疾病具有重要意义。

DESCRIPTION (provided by applicant): Pulmonary alveolar proteinosis (PAP) is a syndrome characterized by accumulation of surfactant in alveolar macrophages (AMs) and alveoli resulting in respiratory failure and increased mortality from infection. For nearly 4 decades, the only available therapy was whole lung lavage, a highly invasive procedure performed at few centers in which one lung is mechanically ventilated while the other is repeatedly filled with saline and the chest is percussed vigorously to physically remove surfactant. No advances in pharmacologic therapy occurred due to a lack of pathogenic insight until PAP was discovered in GM-CSF-/- mice, a finding that transformed our concepts of the biological role of GM-CSF and led to novel diagnostics and therapy for PAP. My laboratory has contributed significantly to our understanding that GM-CSF is critical for surfactant homeostasis, AM ontogeny, neutrophil and AM functions, and innate immunity, and that in ~90% of patients, PAP is caused by a high level of GM-CSF autoantibodies (GMAbs). Current evidence suggests GM-CSF regulates surfactant homeostasis via the transcription factors PU.1 and PPAR? by stimulating expression of the lipid transporter, ABCG1: all three are deficient in AMs in GM-CSF-deficient mice and PAP patients. Notwithstanding, questions remain regarding the 1) natural history of PAP, 2) mechanism by which loss of GM-CSF signaling causes PAP, and 3) roles and relationship of PU.1 and PPAR3 in mechanisms by which GM-CSF regulates surfactant clearance and immune functions in AMs. We will use our novel primate model of autoimmune PAP, AM cell lines and PAP biomarkers; an existing murine model of hereditary PAP; and autoimmune and hereditary PAP patients to test our central hypothesis: PAP is caused by reduced GM-CSF?PU.1?PPAR3?ABCG1-dependent excretion of neutral lipids from AMs, which impairs their ability to clear surfactant. This hypothesis will be addressed in 3 specific aims focusing to GM-CSF regulation of myeloid cells. In Aim 1, we will determine the natural history of autoimmune PAP, critical threshold of GMAbs and their effects on myeloid immune functions in our primate model and PAP patients. In Aim 2, the roles of PU.1, PPAR?, and ABCG1 in hereditary PAP caused by CSF2RA or B mutations will be evaluated in vitro using lentiviral-mediated expression in macrophages from mice or humans with hereditary PAP, and in vivo by transplanting ABCG1-transduced bone marrow into CSF2RB-/- mice. In Aim 3, we will determine if GM-CSF regulates surfactant clearance and immune functions in AMs via the PU.1-dependent regulation of PPAR? using novel AM cell lines that do not spontaneously express PU.1, or that also respond to GM-CSF. The transcriptional program that GM-CSF regulates in AMs will be examined in vivo free of secondary effects of surfactant by using our primate model. We will determine if the PPAR? agonist pioglitazone restores AM surfactant clearance in vitro in cells from mice and humans with PAP and in vivo using CSF2RB-/- mice. Anticipated results have implications for PAP pathogenesis and therapy, surfactant homeostasis, and GMAb therapy of common inflammatory diseases.