Lung Macrophage Metabolic Reprogramming in Asbestos-Induced Toxicity

石棉引起的毒性仍然是一个重要的环境条件。尽管有严格的监管 控制，以限制接触，超过130万工人暴露于危险水平的石棉， 每年，这导致美国每年超过10万人死亡。一个关键因素是， 导致石棉暴露毒性严重性的是线粒体ROS（mtROS）的产生， 其调节肺巨噬细胞的交替活化;然而，调节巨噬细胞活化的分子机制是， 巨噬细胞mtROS的产生没有明确定义。NOX酶之一NOX 4诱导mtROS， 各种刺激和几种细胞类型，但巨噬细胞表型的调节是未知的。 由NOX 4介导。我们的初步数据显示，石棉损伤受试者的肺巨噬细胞表达 与正常人相比，NOX 4基因水平更高。显著抑制或沉默NOX 4 消除了mtROS。更重要的是，NOX 1/4抑制剂（GKT 137831）消除了 巨噬细胞选择性激活的巨噬细胞的一个重要特征是代谢重编程 从糖酵解代谢到脂肪酸氧化，这是支持长期细胞活动所必需的。 NOX 1/4抑制减弱石棉诱导的脂肪酸氧化。类似的观察结果在 NOX 4-/-小鼠。来自NOX 4-/-小鼠的肺巨噬细胞显示出与野生型小鼠不同的经典活化， 其具有巨噬细胞的促纤维化活化。此外，NOX 4-/-小鼠受到石棉的保护， 诱导毒性。我们的假设是，NOX 4介导的线粒体ROS调节代谢重编程， 替代激活和肺巨噬细胞的凋亡抵抗，这促进了石棉诱导的 毒性我们将以三个具体目标来检验这一假设。在目的1中，巨噬细胞NOX 4在 巨噬细胞可塑性和石棉诱导毒性的发病机制将在小鼠中进行测试， 巨噬细胞中NOX 4的缺失。目的2将测试NOX 4衍生的mtROS在代谢中的作用。 在石棉暴露的巨噬细胞中使用遗传方法进行重编程和表型可塑性。目标3 将测试NOX 4对石棉损伤的肺巨噬细胞的代谢和表型的作用。 受试者离体接受GKT 137831和RNAi介导的NOX 4沉默。这些研究可能会揭示NOX 4作为 通过调节线粒体代谢来减轻石棉诱导的毒性的理想治疗靶点， 巨噬细胞可塑性

Asbestos-induced toxicity remains to be a significant environmental condition. Despite strict regulatory controls to limit exposure, more than 1.3 million workers are exposed to hazardous levels of asbestos every year, which results in more than 100,000 deaths annually in the United States. One critical factor that contributes to the severity of toxicity in asbestos exposure is the generation of mitochondrial ROS (mtROS), which modulates alternative activation of lung macrophages; however, the molecular mechanism(s) regulating macrophage mtROS generation is not clearly defined. One of the NOX enzymes, NOX4, induces mtROS with various stimuli and in several cell types, but the modulation of the macrophage phenotype is not known to be mediated by NOX4. Our preliminary data show that lung macrophages from asbestos-injured subjects express high levels of the NOX4 gene compared to normal subjects. Inhibition or silencing NOX4 significantly abrogates mtROS. More importantly, the NOX1/4 inhibitor (GKT137831) abolishes alternative activation of macrophages. One important characteristic of alternatively activated macrophages is metabolic reprogramming from glycolytic metabolism to fatty acid oxidation, which is necessary to support long-term cellular activities. NOX1/4 inhibition attenuates asbestos-induced fatty acid oxidation. Similar observations were recapitulated in NOX4-/- mice. Lung macrophages from NOX4-/- mice displayed classical activation unlike the wild type mice, which had pro-fibrotic activation of macrophages. Furthermore, NOX4-/- mice were protected from asbestos- induced toxicity. Our hypothesis is that NOX4-mediated mtROS modulates metabolic reprogramming, alternative activation, and apoptosis resistance of lung macrophages, which promotes asbestos-induced toxicity. We will test this hypothesis with three specific aims. In Aim 1, the role of macrophage NOX4 in macrophage plasticity and in the pathogenesis of asbestos-induced toxicity will be tested in mice harboring a deletion of NOX4 in macrophages. Aim 2 will test the role of NOX4-derived mtROS in metabolic reprogramming and phenotypic plasticity using genetic approaches in asbestos-exposed macrophages. Aim 3 will test the role of NOX4 on the metabolism and phenotype of lung macrophages from asbestos-injured subjects ex vivo with GKT137831 and RNAi-mediated NOX4 silencing. These studies may uncover NOX4 as an ideal therapeutic target to attenuate asbestos-induced toxicity by modulating mitochondrial metabolism and macrophage plasticity.