Impact of endogenous metabolic biases on ototoxic oxidative damage

内源性代谢偏差对耳毒性氧化损伤的影响

• 批准号: 8680203
• 负责人: Heather Colleen Jensen Smith
• 金额: $ 14.45万
• 依托单位: CREIGHTON UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2012
• 资助国家: 美国
• 起止时间: 2012-07-01 至 2016-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8680203
• 关键词: ATP Synthesis Pathway; Agonist; Aminoglycoside Antibiotics; Aminoglycosides; Apical; Bacterial Infections; Biological Assay; Cell Survival; Citric Acid Cycle; Clinical; Complex; Data; Development; Electron Transport; Electrons; Exposure to; Figs - dietary; Fluorescence; Gentamicins; Hair Cells; Image; Individual; Iron; Knowledge; Labyrinth; Lead; Life; Literature; Long-Term Effects; Measurement; Measures; Mediating; Metabolic; Metabolism; Mitochondria; Modeling; Multienzyme Complexes; NADH; Noise; Noise-Induced Hearing Loss; Outer Hair Cells; Oxidation-Reduction; Pathology; Pharmacologic Substance; Pilot Projects; Preparation; Presbycusis; Prevention strategy; Process; Production; Publishing; Reactive Oxygen Species; Regulation; Relative (related person); Research; Role; Series; Site; Source; Succinate Dehydrogenase; Succinates; Testing; Time; Uncertainty; Work; age related; aminoglycoside-induced ototoxicity; cell injury; deafness; equilibration disorder; experience; hair cell regeneration; hearing impairment; inhibitor/antagonist; innovation; mitochondrial dysfunction; ototoxicity; oxidative damage; prevent; research study; response; treatment strategy; two-photon

DESCRIPTION (provided by applicant): This project aims to identify the fundamental metabolic differences between cochlear inner and outer hair cells (IHC, OHC) and to determine how these differences mediate cellular responses to ototoxic agents. Reactive oxygen species (ROS), normal byproducts of metabolism, can rise to lethal levels when mitochondrial metabolism is perturbed. Numerous studies have shown that the production and destructive actions of ROS are common features of multiple hearing loss (HL) pathologies, including aminoglycoside (AG)-induced ototoxicity, noise-induced HL (NIHL), and age-related HL (ARHL). Although there is little doubt that inner ear ROS cause HL, the exact mechanism(s) responsible for ROS production is/are controversial. Recent advances in two-photon confocal imaging of endogenous NADH (metabolic intermediate) allowed the first imaging of real-time changes in mitochondrial metabolism in live cochlear preparations. Using gentamicin (GM) as a representative AG/ototoxic agent, the immediate metabolic responses (NADH fluorescence change) and subsequent production of ROS in IHCs and OHCs will be examined. This proposal pinpoints how ROS production results from a direct GM-induced inhibition of mitochondrial metabolism. In a series of experiments that specifically block mitochondrial ROS production during GM exposure, this proposal provides the first assessment of the previously proposed role of ROS-producing bioactive iron-AG complexes in mediating AG-induced ROS production in cochlear HCs. The innovative model proposed herein describes how differential IHC and OHC ROS production can occur as a consequence of a rapid GM-induced OHC-specific inhibition of NADH production, succinate dehydrogenase activity, and electron flow through the electron transport chain while IHC metabolism remains relatively unfettered. Each Specific Aim will test the validity of the proposed model of GM-induced ototoxicity due to direct modulations of mitochondrial metabolism. Results from these studies will revolutionize our knowledge of AG ototoxicity by 1) differentiating between immediate and long-term effects, 2) determining whether GM-induced ROS production results from mitochondrial dysfunction rather than bioactive iron-AG complexes, and 3) determining whether fundamental differences in IHC and OHC mitochondrial metabolism dictate differential responses to a host of ototoxic agents. By determining the exact site(s) of ROS production, this project spurs the production of new, optimized HL prevention and treatment strategies that specifically target key ROS production site(s). Agents that site- specifically reduce metabolic ROS production and subsequent HC loss will be identified as key pharmaceutical intermediates poised to reduce the ototoxicity experienced during clinical GM treatment.

描述（由申请人提供）：该项目旨在确定耳蜗内毛细胞（IHC，OHC）之间的基本代谢差异，并确定这些差异如何介导细胞对耳毒剂的反应。当线粒体代谢受干扰时，活性氧（ROS）是代谢的正常副产品，可能会升至致命水平。大量研究表明，ROS的产生和破坏性作用是多种听力损失（HL）病理的常见特征，包括氨基糖苷（AG）诱导的耳毒性，噪声诱导的HL（NIHL）和与年龄相关的HL（ARHL）。尽管毫无疑问，内耳ROS会导致HL，但负责ROS产生的确切机制是有争议的。内源性NADH（代谢中间体）的两光子共聚焦成像的最新进展允许在实时耳蜗制剂中首次对线粒体代谢实时变化进行首次成像。将使用庆大霉素（GM）作为代表性的AG/耳毒剂，将检查立即代谢反应（NADH荧光变化），随后在IHC和OHC中产生ROS。该提案指出了ROS产生是如何由直接GM诱导的线粒体代谢抑制作用引起的。在一系列特异性阻断GM暴露期间线粒体ROS产生的实验中，该建议提供了对先前提出的ROS产生的生物活性铁AG复合物在中介Ag诱导的人工耳蜗HC中的作用的首次评估。本文提出的创新模型描述了差异IHC和OHC ROS的产生如何由于GM诱导的OHC特异性抑制迅速抑制NADH的产生，琥珀酸脱氢酶活性以及电子流经电子传输链时，IHC代谢仍然相对未经被维护。每个特定的目标都将测试由于线粒体代谢的直接调节而导致的GM诱导的耳毒性模型的有效性。 Results from these studies will revolutionize our knowledge of AG ototoxicity by 1) differentiating between immediate and long-term effects, 2) determining whether GM-induced ROS production results from mitochondrial dysfunction rather than bioactive iron-AG complexes, and 3) determining whether fundamental differences in IHC and OHC mitochondrial metabolism dictate differential responses to a host of ototoxic agents.通过确定ROS生产的确切位置，该项目刺激了新的，优化的HL预防和治疗策略的生产，这些策略专门针对关键ROS生产地点。特异性减少代谢ROS产生和随后的HC损失的药物将被确定为有准备降低临床GM治疗过程中经历的耳毒性的关键药物中间体。