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: 9177013
• 负责人: Christopher M Evans
• 金额: $ 70.88万
• 依托单位: NATIONAL JEWISH HEALTH
• 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 2020-07-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/9177013
• 关键词: Acute; Alveolar Macrophages; Alveolus; Apoptosis; Attenuated; Back; Bacteria; Binding; Biological Assay; Breathing; Coughing; Dependence; Deposition; Development; Disease; Down-Regulation; Figs - dietary; Genetically Engineered Mouse; Glycoconjugates; Health; Homeostasis; Host Defense; Immunoglobulins; Infection; Inflammation; Inflammation Mediators; Inflammatory; Inflammatory Response; Injury; Knock-out; Knockout Mice; Laboratories; Lectin Receptors; Life; Ligands; Link; Lung; MUC5B gene; Measurement; Mediating; Modeling; Molecular; Mucins; Mucociliary Clearance; Mucous body substance; Mus; Physiological; Pneumonia; Polysaccharides; Prevention; Production; RNA Interference; Recruitment Activity; Regulation; Resolution; Rest; Role; Sialic Acids; Signal Transduction; Staphylococcus aureus; Stimulus; Testing; Time; glycosylation; in vivo; inflammatory lung disease; macrophage; monocyte; mouse model; novel; particle; pathogen; programs; restoration; selective expression; sialic acid binding Ig-like lectin

PROJECT SUMMARY Each day, the lungs are exposed to billions of particles whose accumulation can potentially cause infection and damage. While it is crucial to defend against these exposures, it is equally important that protection occurs with minimal physiological disruption or injury caused by inflammation. Mucus and macrophage clearance are hallmark non-inflammatory defenses. Particles and pathogens that deposit in the airways are trapped in mucus and eliminated by ciliary and cough forces, while those in alveoli are ingested by alveolar macrophages (AMs). Using Muc5b knockout mice, we previously showed that Muc5b is required for effective mucociliary clearance and for maintaining healthy pools of resident AMs. The primary objective of this proposal is to determine specific mechanisms by which Muc5b regulates AM function during homeostasis and during acute and resolving inflammation. We have identified a novel mechanism that directly links Muc5b to AM function via sialic acid-binding immunoglobulin-type lectin receptor-F (Siglec-F), an inhibitory immunoreceptor that is expressed selectively by resident AMs and is known to bind α2,3-linked sialic acid-containing glycoconjugates. Muc5b is α2,3-sialylated and is an endogenous Siglec-F ligand. We propose that stimulation of Siglec-F by Muc5b calibrates AM inflammatory responses in the resting lung. Thus, in healthy states, the ability of resident AMs to serve protective roles while simultaneously limiting potentially injurious inflammatory responses may occur by a homeostatic programming mechanism mediated by stimulation of Siglec-F by Muc5b. When homeostasis is disrupted by stimuli such as bacteria, a temporary induction of AM inflammatory responsiveness is required. Furthermore, resident AMs are joined by recruited macrophages that arise from circulating monocytes. These recruited monocyte-derived AMs (MDAMs) lack Siglec-F and are highly pro- inflammatory. At the same time that MDAMs are recruited, resident AMs down-regulate their Siglec-F expression and become pro-inflammatory. As inflammation resolves, recruited MDAMs undergo apoptosis and are eliminated, whereas resident AMs restore Siglec-F expression and return to their non-inflammatory states. We postulate that transient reduction of MUC5B:Siglec-F signaling permits an inflammatory response and that restoration of MUC5B:Siglec F signaling is required for its resolution. We hypothesize that stimulation of Siglec-F by Muc5b is a major mechanism for controlling macrophage inflammatory responses during homeostasis and inflammation. We will use wild type and genetically engineered mice, models of acute inflammation, and immunological readouts to test this hypothesis in the following three Specific Aims: 1. Test the hypothesis that during homeostasis, protective AM activities are maintained by MUC5B sialyl glycan- dependent Siglec-F stimulation. 2. Test the hypothesis that MUC5B:Siglec-F dependent inhibitory mechanisms are lost during acute inflammation. 3. Test the hypothesis that re-engagement of MUC5B with Siglec-F on AMs drives the resolution of inflammation.

项目概要 肺部每天都会暴露于数十亿颗粒，这些颗粒的积累可能会导致感染和 损害。虽然防御这些暴露至关重要，但同样重要的是，通过以下方式进行保护： 由炎症引起的生理破坏或损伤最小。粘液和巨噬细胞的清除是 标志性的非炎症防御。沉积在呼吸道中的颗粒和病原体被困在粘液中 并通过纤毛和咳嗽力消除，而肺泡中的那些则被肺泡巨噬细胞（AM）摄入。 使用 Muc5b 敲除小鼠，我们之前表明 Muc5b 是有效的粘膜纤毛清除所必需的 以及维持健康的常驻 AM 池。该提案的主要目标是确定 Muc5b 在稳态和急性和急性期调节 AM 功能的具体机制 解决炎症。我们已经确定了一种新的机制，通过以下方式将 Muc5b 直接连接到 AM 功能： 唾液酸结合免疫球蛋白型凝集素受体-F (Siglec-F)，一种抑制性免疫受体 由常驻 AM 选择性表达，已知可结合 α2,3-连接的含唾液酸的糖复合物。 Muc5b 是 α2,3-唾液酸化的，是内源性 Siglec-F 配体。我们建议通过刺激 Siglec-F Muc5b 校准静息肺中的 AM 炎症反应。因此，在健康状态下，居民的能力 AMs 发挥保护作用，同时限制潜在的有害炎症反应 由 Muc5b 刺激 Siglec-F 介导的稳态编程机制发生。什么时候 体内平衡被细菌等刺激破坏，暂时诱导 AM 炎症 需要反应能力。此外，常驻 AM 还加入了招募的巨噬细胞，这些巨噬细胞来自 循环单核细胞。这些招募的单核细胞来源的 AM (MDAM) 缺乏 Siglec-F，并且高度亲 炎症。在招募 MDAM 的同时，常驻 AM 下调其 Siglec-F 表达并变得促炎。随着炎症消退，招募的 MDAM 会发生凋亡并 被消除，而驻留 AM 恢复 Siglec-F 表达并恢复到非炎症状态。 我们假设 MUC5B:Siglec-F 信号传导的短暂减少会导致炎症反应，并且 MUC5B:Siglec F 信号的恢复需要其解决。我们假设刺激 Muc5b 的 Siglec-F 是控制巨噬细胞炎症反应的主要机制 体内平衡和炎症。我们将使用野生型和基因工程小鼠，即急性传染病模型 炎症和免疫学读数以在以下三个具体目标中检验这一假设： 1. 检验 假设在稳态期间，保护性 AM 活性由 MUC5B 唾液酸聚糖维持 依赖性 Siglec-F 刺激。 2. 检验MUC5B:Siglec-F依赖性抑制的假设 急性炎症期间机制会丢失。 3. 检验 MUC5B 重新接合的假设 AM 上的 Siglec-F 可以促进炎症的消退。