AMPK in the Development and Resolution of Lung Fibrosis

项目总结 特发性肺纤维化(IPF)是一种进行性并最终致命的呼吸系统疾病，影响 美国每年约有15万名患者。IPF是一种老年性疾病，三分之二的IPF患者年龄在60岁以上 确诊时的平均年龄为66岁。有效治疗 干预措施是有限的。我们建议的研究寻求一种解决方案，以有效地阻止和逆转既定的 纤维化症。这项建议由高度机械化的翻译研究组成，这是一项合作的结果 兹米杰斯基博士和萨尼卡尔博士之间。PI和合作者都在以下方面提供了互补的专业知识 细胞代谢，肌成纤维细胞生物学，衰老，肺损伤和修复。我们发现AMP激活 蛋白激酶(AMPK)是一种关键的感受器和代谢调节器，是肺纤维化的有效靶点。特别是， 小鼠肺损伤后肺组织和纤维化区AMPK活性降低。此外，AMPK 失活也与年龄相关的未消退纤维化的易感性有关。AMPK的这种损失 活动与线粒体功能障碍和自噬/有丝分裂功能缺陷有关，这两个事件是相关的 肌成纤维细胞对细胞凋亡的抵抗和细胞外基质周转受损。我们假设，在修复反应中 在肺损伤中，AMPK的激活对于维持线粒体的动态平衡、自噬- 依赖ECM周转和肌成纤维细胞对细胞凋亡的敏感性促进肺组织的分解 纤维化症。我们的假设将通过三个具体目标进行检验。目标1专注于AMPK依赖 激活线粒体生物发生和自噬/有丝分裂吞噬以逆转肌成纤维细胞的激活和 在体外细胞系统和体内肺纤维化小鼠模型中对凋亡的抵抗。目标2 将揭示在肌成纤维细胞中缺乏AMPK激活的机制，来自IPF受试者和 小鼠肺纤维化。目标3将测试AMPK激动剂对年龄相关性肺易感性的疗效 纤维化症。药理学AMPK激活剂的概念验证研究将包括FDA批准的药物 (二甲双胍)和更特异的AMPK激动剂(AICAR)。此外，遗传方法将包括全球 小鼠AMPK基因敲除和成纤维细胞特异性条件缺失；转基因模型也将 包括缺乏生物发生和自噬/有丝分裂吞噬激活剂的小鼠。如果得到证实，我们的研究将 揭示肺纤维化与影响肌成纤维细胞生物能量的AMPK功能障碍的新关系 重编程、细胞凋亡易感性和持续性肺纤维化。该领域的进步包括信令 IPF中AMPK失活和衰老的机制。翻译影响力的实现要靠翻译的重新定位 目的：应用二甲双胍治疗肺纤维化。根据这种药物的安全性概况，如果结果证实抗- 二甲双胍的纤维化作用，可建议进行临床试验，以测试其在IPF中的疗效。

PROJECT SUMMARY Idiopathic pulmonary fibrosis (IPF) is a progressive and ultimately fatal respiratory disorder affecting ~150,000 patients in US each year. IPF is a disease of aging, with two-thirds of IPF patients over 60 years old at the time of presentation and average age of 66 years at the time of diagnosis. Effective therapeutic interventions are limited. Our proposed studies seek a solution to effectively stop and reverse established fibrosis. This proposal consists of highly mechanistic and translational studies that are result of a collaboration between Dr. Zmijewski and Dr. Thannickal. Both PIs and the collaborators bring complementary expertise in cellular metabolism, myofibroblast biology, aging, and lung injury and repair. We found that AMP-activated protein kinase (AMPK), a key sensor and metabolic regulator, is a viable target in lung fibrosis. In particular, AMPK activity is reduced in IPF lungs and the fibrotic regions following lung injury in mice. Moreover, AMPK inactivation is also associated with age-associated susceptibility to non-resolving fibrosis. This loss of AMPK activity is associated with mitochondrial dysfunction and deficient autophagy/mitophagy, events that are linked to myofibroblast resistance to apoptosis and impaired ECM turnover. We hypothesize that, in the repair response to lung injury, AMPK activation is essential for preservation of mitochondrial homeostasis, autophagy- dependent ECM turnover and myofibroblast sensitivity to apoptosis which promotes resolution of lung fibrosis. Our hypothesis will be tested using three specific AIMs. AIM 1 is focused on AMPK-dependent activation of mitochondrial biogenesis and autophagy/mitophagy to reverse myofibroblast activation and resistance to apoptosis, both in ex vivo cellular systems and in a murine model of lung fibrosis in vivo. AIM 2 will reveal mechanisms responsible for lack of AMPK activation in myofibroblasts, from IPF subjects and from fibrotic lungs of mice. AIM 3 will test the efficacy of AMPK activators on age-associated susceptibility to lung fibrosis. Proof-of-concept studies with pharmacological AMPK activators will include an FDA-approved drug (metformin) and a more specific AMPK activator (AICAR). In addition, genetic approaches will include global AMPK knockouts and fibroblast-specific conditional deletion of AMPK in mice; transgenic models will also incorporate mice deficient for activators of biogenesis and autophagy/mitophagy. If confirmed, our studies will reveal new relationships between lung fibrosis and AMPK dysfunction that affects myofibroblast bioenergetic reprogramming, apoptosis susceptibility, and persistent lung fibrosis. Advancements in the field include signaling mechanisms responsible for AMPK inactivation in IPF and aging. Translational impact be realized by the re- purposing of metformin to treat lung fibrosis. Based on the safety profile of this drug, if the results confirm anti- fibrotic actions of metformin, clinical trials could be proposed to test its efficacy in IPF.