Mechanisms of lung macrophage programming by MUC5B during health and disease

MUC5B 在健康和疾病期间对肺巨噬细胞编程的机制

• 批准号: 10467913
• 负责人: Christopher M Evans
• 金额: $ 66.12万
• 依托单位: UNIVERSITY OF COLORADO DENVER
• 依托单位国家: 美国
• 财政年份: 2016
• 资助国家: 美国
• 起止时间: 2016-08-01 至 2026-04-30
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/10467913
• 关键词: Acute; Acute Lung Injury; Address; Alveolar; Alveolar Macrophages; Animals; Award; Bacteria; Binding; Bleomycin; Bone Marrow; Cells; Chimera organism; Chronic; Complication; Data; Deposition; Disease; Distal; Exposure to; Fibrosis; Functional disorder; Galactose; Gases; Genes; Glycoproteins; Health; Homeostasis; Host Defense; Human; Immunoglobulins; Individual; Infection; Inflammation; Inflammatory; Inflammatory Response; Injury; Knockout Mice; Lectin; Leukocytes; Ligands; Ligation; Link; Lipopolysaccharides; Location; Lung; MUC5B gene; Mediating; Molecular; Molecular Conformation; Mucins; Mucous body substance; Mus; Mutant Strains Mice; Neutrophil Infiltration; Outcome; Pathogenesis; Pathologic; Pathway interactions; Patients; Physiological; Polysaccharides; Population; Positioning Attribute; Prevention; Pulmonary Fibrosis; Recovery; Resolution; Respiratory System; Risk; Risk Factors; Role; Sampling; Sialic Acids; Sialyltransferases; Signal Transduction; Signaling Molecule; Structure; Surface; System; Testing; Time; Tissues; Work; alveolar epithelium; base; cell type; fibrotic lung; healing; interest; lung injury; lung repair; macrophage; molecular subtypes; monocyte; mortality; novel; novel strategies; overexpression; particle; prevent; pulmonary function; receptor; recruit; repaired; respiratory; response; response to injury; sialic acid binding Ig-like lectin; sialylation; transcriptome sequencing

PROJECT SUMMARY Mucus and macrophages protect the lungs in health, but they can also contribute to disease following lung injury. How their protective vs. pathological functions are calibrated is poorly understood. We seek to determine mechanisms that control their interactions during responses to lung injury. For mucus-mediated defense, the mucin glycoprotein MUC5B is essential. In mice, absence of Muc5b causes particles and bacteria to accumulate in the lungs, ultimately resulting in early mortality. Despite its requirement for health, MUC5B is an important risk factor in human pulmonary fibrosis, where it is misexpressed in bronchiolar club cells and type 2 alveolar epithelia. Overexpression of Muc5b in these cell types in mice potentiates fibrosis following bleomycin-induced lung injury. These data suggest that the levels and locations of MUC5B/Muc5b- expression are significant factors in the pathogenesis of pulmonary fibrosis. Nonetheless, we do not yet fully understand cellular and molecular mechanisms that explain how MUC5B/Muc5b promotes lung fibrosis. Our recent work suggests that defensive and pathologic effects of airway mucus are regulated by interactions between Muc5b and airspace macrophages (AMs). Resident AMs are present constitutively and are required for non-inflammatory defense. In response to injury, AM pools increase through recruitment of blood monocytes that mature into macrophages. These recruited AMs are more inflammatory than resident AMs, but they are also short-lived, resulting in transient expansion and then contraction of the AM pools. Mechanisms of acute and resolving inflammation that distinguish resident and recruited AM types also impinge on fibrotic repair. The presence of both MUC5B/Muc5b and AMs in distal airspaces, along with our prior observation of AM dysfunction in Muc5b knockout mice, implicate a connection between MUC5B/Muc5b and AM functions. We identified a potential mechanism mediated by mucin glycans and AM glycan receptors. MUC5B/Muc5b is heavily coated with sialic acid (SA) that is attached to galactose via an α2,3-linkage. It is also a ligand for sialic acid binding immunoglobulin like lectin-F (Siglec-F), an inhibitory signaling molecule found almost exclusively on AMs in healthy lungs. We found that a Muc5b-SA-Siglec-F axis is critical for resolving inflammation, as shown by prolonged recruited AM accumulation in mice lacking each component. We now also show that bleomycin-induced lung fibrosis is suppressed in Muc5b-SA-Siglec-F axis disrupted mice. Thus, while protective in response to bacterial inflammation, this mechanism appears to be detrimental in a pro-fibrotic injury setting. We hypothesize that fibrotic repair of lung tissues is mediated by a Muc5b-SA-Siglec-F dependent AM programming mechanism. This will be tested in three aims that test whether 1) promotion of lung fibrosis by Muc5b requires α2,3-sialylation; 2) ligation of Siglec-F by sialylated Muc5b mediates fibrosis; and 3) the Muc5b-SA-Siglec-F axis regulates fibrotic programming of resident vs. recruited AMs.

项目概要 粘液和巨噬细胞可以保护肺部健康，但它们也可能导致肺部疾病 受伤。人们对它们的保护功能与病理功能如何校准知之甚少。我们力求 确定在肺损伤反应期间控制它们相互作用的机制。对于粘液介导的 防御中，粘蛋白糖蛋白MUC5B至关重要。在小鼠中，Muc5b 的缺失会导致颗粒和 细菌在肺部积聚，最终导致早期死亡。尽管对健康有要求， MUC5B 是人类肺纤维化的重要危险因素，在细支气管俱乐部中错误表达 细胞和 2 型肺泡上皮细胞。 Muc5b 在小鼠这些细胞类型中的过度表达会加剧纤维化 博莱霉素引起的肺损伤后。这些数据表明 MUC5B/Muc5b- 的水平和位置 表达是肺纤维化发病机制中的重要因素。尽管如此，我们还没有完全 了解解释 MUC5B/Muc5b 如何促进肺纤维化的细胞和分子机制。我们的 最近的研究表明，气道粘液的防御和病理作用是通过相互作用调节的 Muc5b 和空域巨噬细胞 (AM) 之间。常驻 AM 是基本存在的并且是必需的 用于非炎症防御。为了应对受伤，AM 池通过补充血液而增加 单核细胞成熟为巨噬细胞。这些招募的 AM 比常驻的 AM 更具炎症性，但是 它们的寿命也是短暂的，导致 AM 池短暂扩张然后收缩。机制 区分常驻型和招募型 AM 类型的急性和消退性炎症也会影响纤维化 维修。远端空域中 MUC5B/Muc5b 和 AM 的存在，以及我们之前的观察 Muc5b 敲除小鼠的 AM 功能障碍表明 MUC5B/Muc5b 与 AM 功能之间存在联系。 我们发现了粘蛋白聚糖和 AM 聚糖受体介导的潜在机制。 MUC5B/Muc5b 是 涂有一层厚厚的唾液酸 (SA)，通过 α2,3-键连接到半乳糖上。它也是唾液酸的配体 酸结合免疫球蛋白，如凝集素-F (Siglec-F)，一种几乎唯一发现的抑制性信号分子 健康肺部的AMs。我们发现 Muc5b-SA-Siglec-F 轴对于解决炎症至关重要，因为 缺乏每种成分的小鼠中长期募集的 AM 积累表明了这一点。我们现在还表明 Muc5b-SA-Siglec-F 轴破坏的小鼠中博来霉素诱导的肺纤维化受到抑制。因此，虽然 这种机制对细菌炎症反应具有保护作用，但在促纤维化的情况下似乎是有害的 伤害设定。我们假设肺组织的纤维化修复是由 Muc5b-SA-Siglec-F 介导的 依赖AM编程机制。这将在三个目标中进行测试，测试是否 1) 促进 Muc5b 引起的肺纤维化需要 α2,3-唾液酸化； 2) 通过唾液酸化的 Muc5b 连接 Siglec-F 介导纤维化； 3) Muc5b-SA-Siglec-F 轴调节常驻 AM 与招募 AM 的纤维化编程。