Pulmonary fibrosis is modulated by MCU-mediated macrophage apoptosis resistance

好了！在肺纤维化疾病中，包括特发性肺纤维化(IPF)，肺巨噬细胞 在损伤肺纤维化修复中的决定性作用。巨噬细胞在正常分解过程中发挥着不可或缺的作用。 器官损伤，但也有助于肺纤维化的发病机制，启动免疫反应和 通过产生活性氧(ROS)，特别是线粒体ROS(MtROS)。肺重塑 在肺纤维化过程中，人们知之甚少；然而，单核细胞线粒体生物能量学的变化- 衍生的巨噬细胞正在成为纤维化修复的关键决定因素。MtROS的生成是 与钙(Ca~(2+))有关的钙离子流入线粒体，这在一定程度上受线粒体Ca~(2+)的调节 单板机(MCU)。慢性疾病中的巨噬细胞典型地表现出凋亡抵抗，并延长了 存活率与疾病进展有关。对脂肪酸氧化的代谢重新编程(FAO)是一个关键 巨噬细胞活化的特征。粮农组织的相对效率非常适合满足新陈代谢 修复受伤组织所必需的要求。我们的初步数据显示，肺巨噬细胞来自 IPF受试者PGC-1a表达增加， 一种导致FAO酶活性增加的转录因子--肉碱棕榈酰转移酶IA 线粒体脂转运蛋白(CPT1a)和线粒体Bcl2。 MCU缺乏使PGC-1a表达减弱，显性-阴性(DN)-MCU表达取消 粮农组织。这些发现是相关的，因为通过使用WT和WT产生相互的骨髓嵌合体 MCU+/-小鼠，我们发现接受MCU+/-骨髓移植的小鼠对博莱霉素诱导的小鼠有保护作用 肺纤维化。 我们假设MCU通过肺巨噬细胞代谢重编程来介导肺纤维化。 诱导细胞凋亡抵抗。我们将通过三个目标来检验这一假设。 AIM 1将测试MCU是否调节巨噬细胞代谢重新编程到FAO，以及MCU是否需要 利用单核细胞来源的显性阴性(DN)-MCU表达的小鼠肺纤维化 巨噬细胞。 在目标2中，我们将测试MCU是否通过诱导对FAO的代谢重编程来介导细胞凋亡抵抗 以及利用遗传方法增强与CPT1a结合的抗凋亡Bcl-2蛋白的表达 在单核细胞来源的巨噬细胞中表达dN-MCU或缺失bc l-2的小鼠。 Aim 3将通过以下方式提供MCU在纤维化发展中的重要性的人类生物学证据 确定IPF受试者肺巨噬细胞中MCU的调节是否调节FAO和对 细胞凋亡。了解MCU在肺巨噬细胞中的作用可能为预防 或阻止纤维化的进展。

! In fibrotic disorders of the lung, including idiopathic pulmonary fibrosis (IPF), lung macrophages have a decisive role in fibrotic repair of injured lung. Macrophages play an integral role in the normal resolution of organ injury but also contribute to the pathogenesis of pulmonary fibrosis by initiating an immune response and by generating reactive oxygen species (ROS), particularly mitochondrial ROS (mtROS). Lung remodeling during pulmonary fibrosis is poorly understood; however, changes in mitochondrial bioenergetics in monocyte- derived macrophages are emerging as a critical determinant of fibrotic repair. The generation of mtROS is linked to calcium (Ca2+) influx into the mitochondria, which is regulated, in part, by the mitochondrial Ca2+ uniporter (MCU). Macrophages in chronic disease typically exhibit apoptosis resistance, and their prolonged survival is associated with disease progression. Metabolic reprogramming to fatty acid oxidation (FAO) is a key feature in macrophage activation. The relative efficiency of FAO is well suited to meet the metabolic requirements necessary for the repair of injured tissue. Our preliminary data show that lung macrophages from IPF subjects have increased expression of peroxisome proliferator-activated receptor coactivator-1 (PGC-1a), a transcription factor that leads to increased enzymatic capacity for FAO, carnitine palmitoyltransferase IA (CPT1A), the rate limiting mitochondrial lipid transporter, and mitochondrial Bcl-2 compared to normal subjects. MCU deficiency attenuates PGC-1a expression, and dominant-negative (DN)-MCU expression abrogates FAO. These findings are relevant because by generating reciprocal bone marrow chimeras using WT and MCU+/- mice, we found mice that received MCU+/- bone marrow were protected from bleomycin-induced pulmonary fibrosis. We hypothesize that MCU mediates pulmonary fibrosis by metabolic reprogramming of lung macrophages to induce apoptosis resistance. We will test this hypothesis with three aims. Aim 1 will test if MCU modulates macrophage metabolic reprogramming to FAO and if MCU is required for pulmonary fibrosis utilizing mice harboring expression of a dominant-negative (DN)-MCU in monocyte-derived macrophages. In Aim 2, we will test if MCU mediates apoptosis resistance by inducing metabolic reprogramming to FAO and enhancing expression of anti-apoptotic Bcl-2 proteins that bind to CPT1a using genetic approaches and in mice harboring expression of DN-MCU or a deletion of Bcl-2 in monocyte-derived macrophages. Aim 3 will provide human biological evidence of the importance of MCU in fibrosis development by determining if modulation of MCU in lung macrophages from IPF subjects regulates FAO and resistance to apoptosis. Understanding the role of MCU in lung macrophages may provide an important target for preventing or halting progression of fibrosis.