Oxidized Phospholipids Derived from Apoptotic Pneumocytes Drives Macrophage Activation and Initiates Lung Fibrosis

凋亡肺细胞衍生的氧化磷脂驱动巨噬细胞激活并引发肺纤维化

基本信息

批准号：
10293745
负责人：
KEVIN KEEWOUN KIM
金额：
$ 61.7万
依托单位：
UNIVERSITY OF MICHIGAN AT ANN ARBOR
依托单位国家：
美国
项目类别：
财政年份：
2021
资助国家：
美国
起止时间：
2021-09-01 至 2025-05-31
项目状态：
未结题

来源：
https://reporter.nih.gov/project-details/10293745
关键词：
Address Alveolar Alveolar Macrophages Animal Model Apoptosis Apoptotic Attenuated Automobile Driving Bleomycin Bone Marrow Bone Marrow Transplantation CCL2 gene CD36 gene Catabolism Cells Cessation of life Chimera organism Chronic Cicatrix Data Defect Development Diagnosis Disease Disease Progression Disease model Enzymes Epithelial Epithelial Cells Etiology Exhibits Exposure to Fibroblasts Fibrosis Generations Goals Human Impairment In Vitro Ingestion Injury Knockout Mice Knowledge Lead Ligands Link Lipids Lung Lung diseases Macrophage Activation Mediating Medical Modeling Mus Null Lymphocytes Organ Organ failure Oxidative Stress Oxides Pathogenesis Pathology Pathway interactions Phenotype Phospholipase A2 Phospholipids Publishing Pulmonary Fibrosis Recombinant Proteins Recombinants Reporting Research Project Grants Role Sampling Secondary to Shortness of Breath Signal Pathway Signal Transduction Systemic disease Testing Time Transforming Growth Factor beta Transgenic Mice Translating Transplantation Chimera alveolar epithelium cell injury chemokine experimental study idiopathic pulmonary fibrosis in vivo inhibitor/antagonist injured interstitial lung injury macrophage monocyte mouse model new therapeutic target novel novel therapeutics oxidation pneumocyte receptor recruit repaired response surfactant targeted treatment tissue injury uptake

项目摘要

Project Summary Progressive lung fibrosis is a feature of systemic diseases and chronic injury but can also occur in the absence of any known etiology as with Idiopathic Pulmonary Fibrosis (IPF). IPF is a devastating disorder with a median survival of ~4 years from time of diagnosis and current medical therapy only modestly slows disease progression. Even fibrosis from known causes can lead to a difficult progressive course, thsu it is vital that the pathogenesis of fibrosis is more precisely elucidated in order to identify novel therapeutic targets. Recent studies from both human fibrotic diseases and animal models have identified a critical role for type II alveolar epithelial cell (AEC2) injury and apoptosis in the initiation of interstitial scarring. However, the downstream pathways that translate AEC2 injury/death into fibrosis remain undefined. Our preliminary data demonstrate that an array of AEC2 insults drives their expression of CCL2/CCL12, chemokines involved in pro-fibrotic monocyte/macrophage recruitment. The importance of this response was confirmed by demonstrating that mice deficient in AEC2-derived CCL12 developed attenuated fibrosis in a murine model. AEC2 injury can also progress to apoptosis with an accompanying oxidation of their abundant phospholipid stores, and we discovered that uptake and accumulation of oxidized phospholipid (oxPL) derived from apoptotic AEC2s (either released or retained within apoptotic bodies) induces a pro-fibrotic phenotypic switch in the ingesting lung macrophage. Administration of apoptotic AEC2s or oxPL into the lungs of uninjured mice is sufficient to drive lung fibrosis and this uptake is mediated by CD36. The accumulation of oxPL within macrophages is also determined by its catabolism which we have shown is regulated primarily by lysosomal phospholipase A2 (LPLA2). Our preliminary results indicate that the rapid intracellular degradation of oxPL by LPLA2 in alveolar macrophages can minimize macrophage activation. Compared to resident macrophages, monocyte-derived macrophages that are recruited to the injured lung exhibit a greater pro-fibrotic response to oxPL accumulation due to their decreases expression of LPLA2. These preliminary data motivate our central hypothesis that AEC2 injury/apoptosis results in a coordinated response in which the elaboration of CCL12 from injured AECs attracts monocyte-derived macrophages to the alveolar space where they engulf and accumulate oxPL resulting in robust pro-fibrotic activation. We will pursue a multifaceted approach using in vitro studies of primary murine and human macrophages with in vivo mouse experiments using novel transgenic mice, bone marrow transplant chimeras, and complementary models of lung fibrosis. We have formed a synergistic team with expertise in lipids, monocyte/macrophages, and AEC2s. Our research project specifically addresses a recognized knowledge gap in fibrosis pathogenesis. Importantly, the results of these studies will define previously unexplored mechanisms that critically regulate fibrosis and will inform the development of novel therapies.

项目概要进行性肺纤维化是全身性疾病和慢性损伤的一个特征，但也可能发生在没有任何已知的特发性肺纤维化（IPF）病因。 IPF 是一种毁灭性的疾病从诊断之日起中位生存期约为 4 年，目前的药物治疗只能适度减缓疾病进展。即使是已知原因引起的纤维化也可能导致困难的进展过程，因此至关重要的是更准确地阐明纤维化的发病机制，以确定新的治疗靶点。最近对人类纤维化疾病和动物模型的研究已经确定了 II 型纤维化疾病的关键作用肺泡上皮细胞（AEC2）损伤和细胞凋亡在间质疤痕形成过程中的作用。然而，将 AEC2 损伤/死亡转化为纤维化的下游途径仍不清楚。我们的初步数据证明一系列 AEC2 损伤驱动 CCL2/CCL12 的表达，这些趋化因子参与促纤维化单核细胞/巨噬细胞募集。这一回应的重要性得到了证实证明缺乏 AEC2 衍生的 CCL12 的小鼠在小鼠模型中纤维化程度减轻。 AEC2 损伤还可进展为细胞凋亡，并伴随其丰富磷脂的氧化储存，我们发现氧化磷脂 (oxPL) 的吸收和积累源自凋亡 AEC2（释放或保留在凋亡体内）诱导促纤维化表型转换在吞噬肺巨噬细胞中。将凋亡的 AEC2 或 oxPL 注入未受伤小鼠的肺部足以驱动肺纤维化，并且这种摄取是由 CD36 介导的。 oxPL的积累巨噬细胞也由其分解代谢决定，我们已经证明，分解代谢主要受溶酶体调节磷脂酶 A2 (LPLA2)。我们的初步结果表明，oxPL 的快速细胞内降解肺泡巨噬细胞中的 LPLA2 可以最大限度地减少巨噬细胞的激活。与常驻巨噬细胞相比，被募集到受损肺部的单核细胞衍生的巨噬细胞表现出更强的促纤维化反应由于 LPLA2 表达降低，oxPL 积累。这些初步数据激发了我们的中心假设，即 AEC2 损伤/凋亡导致协调受损 AEC 产生的 CCL12 会吸引单核细胞衍生的巨噬细胞它们吞噬并积聚 oxPL 的肺泡腔，导致强大的促纤维化激活。我们将利用原代小鼠和人类巨噬细胞的体外研究和体内研究，寻求多方面的方法使用新型转基因小鼠、骨髓移植嵌合体和互补的小鼠实验肺纤维化模型。我们组建了一支在脂质、单核细胞/巨噬细胞、和 AEC2。我们的研究项目专门解决了纤维化发病机制中公认的知识空白。重要的是，这些研究的结果将定义以前未探索过的严格调节机制纤维化并将为新疗法的开发提供信息。