Metabolic Regulation of Pro-Fibrotic Macrophages in Pulmonary Fibrosis

特发性肺纤维化（IPF）的患病率正在增加，最近批准的抗纤维化药物 治疗的效果有限。肺泡巨噬细胞在肺损伤和修复中具有重要作用。巨噬 在慢性疾病中，通常表现出细胞凋亡抗性，且其延长存活通常与 疾病进展是由于向促纤维化表型的极化。线粒体ROS的产生 肺泡巨噬细胞中的线粒体活性氧（mtROS）调节促纤维化极化;然而， 在纤维化中调节巨噬细胞mtROS没有明确定义。NOX酶之一NOX 4产生 mtROS与各种刺激和几种细胞类型，但巨噬细胞表型的调节没有 与NOX 4有关。我们的初步数据显示，IPF受试者的肺泡巨噬细胞表达高表达， 与正常受试者相比，NOX 4基因的水平，并且有更多的NOX 4定位在线粒体中， IPF肺泡巨噬细胞。使用GKT 137831抑制NOX 1/4或沉默NOX 4可显著消除 mtROS。此外，GKT 137831下调巨噬细胞的促纤维化极化，并消除脂肪肝。 酸氧化和氧化磷酸化，这是促纤维化巨噬细胞的特征代谢。 在体内，N 0X 4调节肺泡巨噬细胞向促纤维化表型的极化。此外，本发明还提供了一种方法， 保护免受肺纤维化的NOX 4-/-小鼠，在肺纤维化中具有显著更少的肺泡巨噬细胞。 BAL液提示募集缺陷或缺乏凋亡抵抗。我们的假设是 NOX 4调节巨噬细胞线粒体活性氧和代谢，使肺泡巨噬细胞成为促纤维化细胞， 表型是纤维化发展的关键。我们将以三个具体目标来检验这一假设。要求1 将确定Nox 1/4抑制剂（GKT 137831）是否调节肺泡巨噬细胞代谢和表型 在入组IIb期临床试验的IPF受试者中。在目标2中，我们将确定NOX 4在 使用药理学调节线粒体代谢和肺泡巨噬细胞表型（GKT 137831） 和遗传学方法。目的3将确定NOX 4在调节纤维化中的巨噬细胞特异性作用。 利用在巨噬细胞中具有条件性缺失NOX 4的小鼠的对肺损伤的应答。这些研究 可以描述NOX 4作为代谢和巨噬细胞可塑性的重要调节剂，这表明它是一种理想的 治疗目标是阻止进展或逆转肺纤维化。

Idiopathic pulmonary fibrosis (IPF) is increasing in prevalence, and the recently approved anti-fibrotic therapies have limited efficacy. Alveolar macrophages have a critical role lung injury and repair. Macrophages in chronic disease typically exhibit apoptosis resistance, and their prolonged survival is generally associated with disease progression due to polarization to a pro-fibrotic phenotype. The generation of mitochondrial ROS (mtROS) in alveolar macrophages modulates pro-fibrotic polarization; however, the molecular mechanism(s) regulating macrophage mtROS in fibrosis is not clearly defined. One of the NOX enzymes, NOX4, generates mtROS with various stimuli and in several cell types, but the modulation of the macrophage phenotype has not been linked to NOX4. Our preliminary data show that alveolar macrophages from IPF subjects express high levels of the NOX4 gene compared to normal subjects, and there is more NOX4 localized in the mitochondria of IPF alveolar macrophages. NOX1/4 inhibition with GKT137831 or silencing NOX4 significantly abrogates mtROS. Moreover, GKT137831 down regulates pro-fibrotic polarization of macrophages and abrogates fatty acid oxidation and oxidative phosphorylation, which is characteristic metabolism for pro-fibrotic macrophages. In vivo, NOX4 modulates the polarization of alveolar macrophages to a pro-fibrotic phenotype. In addition, NOX4-/- mice, which are protected from pulmonary fibrosis, have significantly less alveolar macrophages in the BAL fluid suggesting either a defect in recruitment or an absence of apoptosis resistance. Our hypothesis is that NOX4 modulates macrophage mtROS and metabolism to polarize alveolar macrophages to a pro-fibrotic phenotype that is critical for fibrosis development. We will test this hypothesis with three specific aims. Aim 1 will determine if the Nox1/4 inhibitor (GKT137831) modulates alveolar macrophage metabolism and phenotype in IPF subjects enrolled in a Phase IIb clinical trial. In Aim 2, we will determine the effects of NOX4 in regulating mitochondrial metabolism and alveolar macrophage phenotype using pharmacologic (GKT137831) and genetic approaches. Aim 3 will determine macrophage-specific roles of NOX4 in regulating fibrotic responses to lung injury utilizing mice harboring a conditional deletion of NOX4 in macrophages. These studies may delineate NOX4 as a critical regulator of metabolism and macrophage plasticity suggesting it is an ideal therapeutic target to halt progression or reverse pulmonary fibrosis.