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 治疗方法的疗效有限。肺泡巨噬细胞在肺损伤修复中具有重要作用。巨噬细胞 在慢性病中通常表现出细胞凋亡抵抗，它们的存活时间延长通常与 由于分化为促纤维化表型而导致疾病进展。线粒体ROS的产生 肺泡巨噬细胞(MtROS)调节促纤维化极化；然而，其分子机制(S) 巨噬细胞mtROS在纤维化中的调节作用尚不清楚。NOX的一种酶NOX4会产生 MtROS与各种刺激和几种细胞类型有关，但巨噬细胞表型的调节没有 已与NOX4联系在一起。我们的初步数据显示，IPF受试者的肺泡巨噬细胞高表达 NOX4基因水平与正常人相比，线粒体中有更多的NOX4基因定位 肺泡巨噬细胞。用GKT137831抑制NOX1/4或沉默NOX4可显著消除 MtROS。此外，GKT137831下调巨噬细胞的促纤维化极化，并消除脂肪 酸性氧化和氧化磷酸化，这是促纤维化巨噬细胞的特征代谢。 在体内，NOX4将肺泡巨噬细胞的极化调节为促纤维化表型。此外, NOX4-/-小鼠在肺纤维化中受到保护，其肺泡巨噬细胞显著减少 BAL液提示募集缺陷或缺乏细胞凋亡抵抗。我们的假设是 NOX4调节巨噬细胞mtROS和代谢，使肺泡巨噬细胞极化为促纤维化 对纤维化的发展至关重要的表型。我们将通过三个具体目标来检验这一假设。目标1 将确定Nox1/4抑制剂(GKT137831)是否调节肺泡巨噬细胞的代谢和表型 在参加IIb期临床试验的IPF受试者中。在目标2中，我们将确定NOX4对 用药理学调节线粒体代谢和肺泡巨噬细胞表型(GKT137831) 和遗传方法。AIM 3将确定NOX4在调节纤维化中的巨噬细胞特异性作用 利用巨噬细胞中NOX4有条件缺失的小鼠对肺损伤的反应。这些研究 可能将NOX4描述为新陈代谢和巨噬细胞可塑性的关键调节因子，这表明它是一个理想的 治疗的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.