Sirtuins in Lung Aging and Fibrosis

Sirtuins 在肺衰老和纤维化中的作用

• 批准号: 9210543
• 负责人: Victor J. Thannickal
• 金额: --
• 依托单位: BIRMINGHAM VA MEDICAL CENTER
• 依托单位国家: 美国
• 财政年份: 2016
• 资助国家: 美国
• 起止时间: 2016-01-01 至 2019-12-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/9210543
• 关键词: Accounting; Acetylation; Affect; Age; Aging; Animals; Apoptosis; Applications Grants; Bioenergetics; Biological; Bleomycin; Blood Vessels; Cell Aging; Cells; Cicatrix; Clinical; Collagen; DNA Methylation; Data; Development; Diagnosis; Disease; Down-Regulation; Enzymes; Epigenetic Process; Equilibrium; Fibroblasts; Fibrosis; Gases; Genes; Genetic; Hamman-Rich syndrome; Heart; Human; Immunohistochemistry; Incidence; Kidney; Knock-out; Laboratories; Link; Liver; Lung; Lung diseases; Maintenance; Mediating; Mesenchymal; Mitochondria; Mitochondrial Proteins; Modeling; Molecular; Morbidity - disease rate; Mus; Myofibroblast; NADPH Oxidase; Oxidation-Reduction; Pathogenesis; Pharmaceutical Preparations; Phase; Phenotype; Pirfenidone; Population; Prevalence; Pulmonary Fibrosis; Reactive Oxygen Species; Resistance; Resolution; Respiratory Failure; Role; Signal Transduction; Sirtuins; Structure of parenchyma of lung; Survival Rate; Testing; Time; Tissues; United States; United States Department of Veterans Affairs; age related; aged; body system; burden of illness; clinical efficacy; fibrogenesis; histone modification; human subject; improved; in vivo; insight; lung injury; mitochondrial dysfunction; mortality; mouse model; novel; novel therapeutic intervention; novel therapeutics; older patient; public health relevance; response; senescence

 DESCRIPTION (provided by applicant) Idiopathic pulmonary fibrosis (IPF) is a disease of aging. IPF carries a high morbidity and mortality, with a median survival rate of less than three years. The incidence and prevalence of IPF increase drastically with age; however, despite this strong association, cellular/molecular mechanisms that account for the aging predilection to fibrotic disease have not been elucidated. Recent studies from our laboratory have identified a reactive oxygen species (ROS)-generating enzyme, NADPH oxidase-4 (Nox4), in mediating differentiation of fibroblasts (Fbs) to myofibroblasts (MFbs), key effectors of fibrogenesis, and in in-vivo lung fibrosis in murine models of lung injury. Our preliminary studies indicate that the biological actions of Nox4 may be modulated by the expression of SIRT3, a mitochondrial sirtuin. Both cellular senescence and TGF-β1 mediate suppression of SIRT3; our preliminary studies support a role for epigenetic silencing of SIRT3 involving both DNA methylation and histone modification. Decreased expression of SIRT3 promotes a senescent and pro-fibrotic Fb phenotype. TGF-β1-induced down-regulation of SIRT3 is associated with hyper-acetylation of mitochondrial proteins, supporting a role for altered mitochondrial bioenergetics in MFbs. Human subjects with IPF express low levels of SIRT3 in myofibroblastic foci (by immunohistochemistry), as well as in ex-vivo Fbs isolated from IPF lungs. We have developed a novel aging model of non-resolving fibrosis in mice; fibrosis in young mice (2 months) resolves by >50% by 4 months post-bleomycin, whereas aged mice (18 months) show persistent fibrotic response. While SIRT3 levels decrease during the fibrogenic phase in both groups, young mice demonstrate a capacity to recover SIRT3 levels during resolution; in contrast, aged mice manifest sustained down-regulation of SIRT3. The central hypothesis to be tested in this grant proposal is that, in the context of aging, lung injury results in sustained, epigenetically-regulated SIRT3 silencing that leads to mitochondrial dysfunction, MFb senescence and apoptosis resistance, leading to persistent fibrosis with aging. Our specific aims are to: (1) determine epigenetic mechanisms for SIRT3 down-regulation with cellular senescence and with TGF-β1 signaling in lung Fbs; (2) determine the role of SIRT3 in regulating mitochondrial bioenergetics, Fb senescence and apoptosis resistance; (3) determine whether whole-animal SIRT3 knockout and/or conditional genetic deletion of SIRT3 in collagen-producing/mesenchymal cells induce(s) persistent fibrosis in young mice. The completion of the Aims in this proposal will: (a) elucidate epigenetic mechanisms that control SIRT3 expression with cellular senescence/aging; (b) provide mechanistic insights into the role of SIRT3 in maintenance of mitochondrial bioenergetics and cellular plasticity/fate; (c) provide proof-of-concept that SIRT3 induction in the context of age-associated fibrosis facilitates fibrosis resolution, uncovering a novel therapeutic approach to non-resolving fibrotic disorders such as IPF.

 描述（由申请人提供） 特发性肺纤维化（IPF）是一种衰老疾病。 IPF 的发病率和死亡率很高，中位生存率不到三年。 IPF 的发病率和患病率随着年龄的增长而急剧增加；然而，尽管存在这种密切的关联，但导致衰老易患纤维化疾病的细胞/分子机制尚未阐明。 我们实验室最近的研究发现，一种活性氧 (ROS) 生成酶 NADPH 氧化酶 4 (Nox4) 在介导成纤维细胞 (Fbs) 向肌成纤维细胞 (MFbs) 的分化（纤维形成的关键效应物）以及小鼠肺损伤模型的体内肺纤维化中发挥作用。我们的初步研究表明，Nox4 的生物学作用可能受到线粒体 Sirtuin SIRT3 表达的调节。细胞衰老和 TGF-β1 都会介导 SIRT3 的抑制；我们的初步研究支持 SIRT3 表观遗传沉默的作用，涉及 DNA 甲基化和组蛋白修饰。 SIRT3 表达的减少会促进衰老和促纤维化的 Fb 表型。 TGF-β1 诱导的 SIRT3 下调与线粒体蛋白的过度乙酰化相​​关，支持 MFb 中线粒体生物能改变的作用。患有 IPF 的人类受试者在肌纤维母细胞病灶（通过免疫组织化学）以及从 IPF 肺部分离的离体 Fb 中表达低水平的 SIRT3。我们开发了一种新的小鼠非消退性纤维化衰老模型；年轻小鼠（2 个月）的纤维化在博来霉素治疗后 4 个月内消退了 50% 以上，而老年小鼠（18 个月）则表现出持续的纤维化反应。虽然两组小鼠的 SIRT3 水平在纤维化阶段均有所下降，但年轻小鼠表现出在消退期间恢复 SIRT3 水平的能力；相反，老年小鼠表现出 SIRT3 的持续下调。 本拨款提案要测试的中心假设是，在衰老的背景下，肺损伤会导致持续的、表观遗传调节的 SIRT3 沉默，从而导致线粒体功能障碍、MFb 衰老和细胞凋亡抵抗，从而导致衰老过程中的持续纤维化。 我们的具体目标是：(1) 确定 SIRT3 下调与细胞衰老和肺 Fb 中 TGF-β1 信号传导的表观遗传机制； (2)确定SIRT3在调节线粒体生物能、Fb衰老和抗凋亡中的作用； (3) 确定整个动物 SIRT3 敲除和/或胶原蛋白生成细胞/间充质细胞中 SIRT3 的条件性基因缺失是否会诱导幼年小鼠的持续纤维化。 完成本提案中的目标将： (a) 阐明控制 SIRT3 表达与细胞衰老/衰老的表观遗传机制； (b) 提供有关 SIRT3 在维持线粒体生物能学和细胞可塑性/命运中的作用的机制见解； (c) 提供概念证明，证明在年龄相关的纤维化背景下诱导 SIRT3 有助于纤维化消退，从而揭示了一种针对 IPF 等非消退性纤维化疾病的新治疗方法。