AMPK in the Development and Resolution of Lung Fibrosis

项目摘要 特发性肺纤维化（IPF）是一种进行性和最终致命的呼吸系统疾病， 美国每年约有150，000例患者。IPF是一种老龄化疾病，三分之二的IPF患者年龄超过60岁 诊断时的平均年龄为66岁。有效治疗 干预是有限的。我们建议的研究寻求一种解决方案，以有效地阻止和扭转既定的 纤维化这项建议包括高度机械和翻译的研究，是合作的结果 Zmijewski博士和Thannickal博士之间。PI和合作者都带来了互补的专业知识， 细胞代谢、肌成纤维细胞生物学、衰老和肺损伤和修复。我们发现AMP激活的 蛋白激酶（AMPK）是一种关键的传感器和代谢调节剂，是肺纤维化的可行靶点。特别是， AMPK活性在IPF肺和小鼠肺损伤后的纤维化区域中降低。此外，AMPK 失活还与年龄相关的对非消退性纤维化的易感性有关。AMPK的丢失 活性与线粒体功能障碍和自噬/线粒体自噬缺陷有关， 肌成纤维细胞对凋亡的抵抗和受损的ECM周转。我们假设在修复反应中 在肺损伤中，AMPK激活对于维持线粒体稳态、自噬、 依赖性ECM更新和肌成纤维细胞对细胞凋亡的敏感性，促进肺消退 纤维化我们的假设将使用三个特定的AIM进行测试。AIM 1专注于AMPK依赖性 激活线粒体生物发生和自噬/线粒体自噬以逆转肌成纤维细胞激活， 在离体细胞系统和体内肺纤维化的鼠模型中，目的2 将揭示肌成纤维细胞缺乏AMPK激活的机制，来自IPF受试者和来自 小鼠的纤维化肺。目的3将测试AMPK激活剂对与年龄相关的肺易感性的有效性。 纤维化药理学AMPK激活剂的概念验证研究将包括FDA批准的药物 （二甲双胍）和更特异性的AMPK激活剂（AICAR）。此外，遗传方法将包括全球性的 AMPK敲除和成纤维细胞特异性AMPK条件性缺失小鼠;转基因模型也将 掺入缺乏生物发生和自噬/线粒体自噬激活物的小鼠。如果得到证实，我们的研究将 揭示了肺纤维化和AMPK功能障碍之间的新关系，AMPK功能障碍影响肌成纤维细胞生物能量 重编程、凋亡易感性和持续性肺纤维化。该领域的进步包括信号 在IPF和衰老中负责AMPK失活的机制。翻译的影响是通过重新实现的， 二甲双胍治疗肺纤维化的目的。基于这种药物的安全性，如果结果证实抗- 由于二甲双胍的纤维化作用，可建议进行临床试验以检测其在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.