Macrophage Modulation of Lung Fibrosis

肺纤维化已成为系统性硬化症患者死亡的主要原因 (SSc)/硬皮病，但目前可用的疗法仅是边缘有效的。虽然最近的工作从 几组研究人员认为，肺巨噬细胞在肺动脉粥样硬化的发生中起着关键作用。 尽管在SSc患者中存在肺纤维化，但这仍然是一个有争议的领域，因为肺纤维化的特定人群 驱动纤维化的巨噬细胞及其分子机制在很大程度上仍然存在， 未知在此之前，我们已经开发了新的工具来阐明巨噬细胞的异质性 包括谱系标记、流式细胞术和转录谱分析， 检查组织驻留肺泡巨噬细胞的差异作用，与单核细胞衍生的 在纤维化的发病机制中，肺泡巨噬细胞被募集到肺中。使用无偏转录 在实验性巨噬细胞发育过程中流式分选的巨噬细胞群体的RNA序列分析（RNAseq）。 在纤维化中，我们鉴定了单核细胞向肺泡巨噬细胞分化和纤维化的遗传特征。 此外，我们已经开发了一种小鼠模型，该模型缺乏致病性单核细胞衍生的巨噬细胞， 因此不能发展成肺纤维化。具体来说，巨噬细胞特异性缺失caspase-8的小鼠， 半胱氨酸-天冬氨酸蛋白酶最初被鉴定为凋亡性死亡受体途径的关键起始物 和坏死性凋亡抑制因子（CreLysMCasp 8 fl/fl或CreCD 11 cCasp 8 fl/fl），显示出显著减弱的纤维化 以及募集的单核细胞不能分化为促纤维化单核细胞来源的Siglec Flow 用博来霉素或编码活性形式的腺病毒进行气管内治疗后的巨噬细胞 与Casp 8 fl/fl、CreLysM或CreCD 11 c小鼠相比，TGF-β的表达。因此，该模型是理解的理想工具 肺损伤时单核细胞向促纤维化肺泡巨噬细胞的分化。这些模型 系统将允许我们将转录数据应用于SSc患者单核细胞的研究 在人源化小鼠的肺中分化成肺泡巨噬细胞， 肺移植时的SSc患者。我们的研究将验证一个假设， 单核细胞分化为促纤维化Siglec Flow肺泡巨噬细胞对于 在三个相互关联的特定目标中，在小鼠和人类中肺纤维化的发展。

Pulmonary fibrosis has emerged as the leading cause of death in patients with systemic sclerosis (SSc)/scleroderma, yet currently available therapies are only marginally effective. While recent work from several groups of investigators suggests a key role for lung macrophages in the development of pulmonary fibrosis in patients with SSc, this remains an area of controversy as the specific population(s) of lung macrophages that drive fibrosis and the molecular mechanisms by which they do so remain largely unknown. In advance of this proposal, we have developed novel tools to elucidate macrophage heterogeneity in the mouse and human lung including lineage tagging, flow cytometry and transcriptional profiling in order to examine the differential role of tissue-resident alveolar macrophages, as compared to the monocyte-derived alveolar macrophages recruited to the lung, in the pathogenesis of fibrosis. Using unbiased transcriptional analysis (RNAseq) of flow-sorted macrophage populations over the course of the development of experimental fibrosis, we identified genetic signatures of monocyte to alveolar macrophage differentiation and fibrosis. Moreover, we have developed a murine model, which lacks the pathogenic monocyte-derived macrophage and is thus unable to develop lung fibrosis. Specifically, mice with macrophage-specific deletion of caspase-8, a cysteine-aspartic acid protease originally identified as a key initiator of the apoptotic death receptor pathway and suppressor of necroptosis (CreLysMCasp8fl/fl or CreCD11cCasp8fl/fl), showed significantly attenuated fibrosis and an inability for recruited monocytes to differentiate into pro-fibrotic monocyte-derived Siglec Flow macrophages following intratracheal treatment with either bleomycin or an adenovirus encoding an active form of TGF-β as compared to Casp8fl/fl, CreLysM or CreCD11c mice. Thus, this model is an ideal to tool to understand the differentiation of monocytes into pro-fibrotic alveolar macrophages in response to lung injury. These model systems will allow us to apply the transcriptional data to the study of monocytes from patients with SSc differentiated into alveolar macrophages in the lungs of humanized mice and alveolar macrophages obtained from patients with SSc at the time of lung transplantation. Our studies will test the hypothesis that monocyte differentiation into pro-fibrotic Siglec Flow alveolar macrophages is essential for the development of lung fibrosis in both mice and humans in three interrelated specific aims.