Mechanisms of Traumatic Retinal Injury: Targeting the Arginase Pathway

外伤性视网膜损伤的机制：针对精氨酸酶途径

• 批准号: 9031913
• 负责人: Ruth B Caldwell
• 金额: --
• 依托单位: CHARLIE NORWOOD 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/9031913
• 关键词: 3-nitrotyrosine; Acute; Arginine; Attenuated; Axon; Biochemical; Biological Markers; Blindness; Blood Vessels; Cells; Complex; Data; Development; Early Intervention; Edema; Enzymes; Eye; Eye Injuries; Freedom; Functional disorder; Glaucoma; Goals; Health; Inflammation; Injury; Ischemia; Knowledge; Lead; Macrophage Activation; Mediating; Mediator of activation protein; Metabolic Pathway; Metabolism; Microglia; Mission; Mitochondria; Modeling; Molecular; Nerve Crush; Neurons; Nitric Oxide Synthase; Optic Nerve; Optic Nerve Injuries; Ornithine; Outcome; Oxidants; Oxidative Stress; Pathway interactions; Permeability; Peroxonitrite; Personal Satisfaction; Polyamines; Prevention; Production; Research; Retina; Retinal; Retinal Ganglion Cells; Risk; Safety; Secondary to; Signal Transduction; Structure; Study models; Superoxides; Testing; Therapeutic; Therapeutic Agents; Therapeutic Intervention; Trauma; Traumatic injury; Treatment Efficacy; Validation; Vascular Diseases; Vasodilation; Veterans; Vision; Visual; Wild Type Mouse; Work; arginase; base; combat; effective therapy; functional outcomes; improved; in vivo; in vivo imaging; inhibitor/antagonist; injured; innovation; knock-down; mouse model; neurovascular; neurovascular injury; new therapeutic target; novel; novel strategies; novel therapeutics; operation; oxidation; polyamine oxidase; preclinical study; prevent; protective effect; public health relevance; repaired; research study; retinal neuron; treatment effect; vascular inflammation

 DESCRIPTION (provided by applicant): The long term goal of this research is to delineate the molecular mechanisms that lead to trauma-induced retinal neuronal and vascular injury and identify novel strategies to prevent or reverse the damage and preserve vision. The lack of understanding of the detailed molecular mechanisms by which ocular trauma damages the retinal neurons and vascular cells represents a critical knowledge gap in developing effective therapies. Therefore, the goal of this research is to define these mechanisms and identify innovative approaches to prevent such damage, improve functional outcomes and reduce the risk of blindness to veterans returning from the battlefield. Preliminary data suggest that ischemia or trauma-induced activation of the mitochondrial, ureahydrolase enzyme arginase 2 causes microglia/macrophage activation, inflammation and neurovascular degeneration by increasing oxidative stress. Overactive arginase can increase oxidative stress by 1) decreasing the L-arginine supply needed by nitric oxide synthase (NOS) to produce NO, thereby causing NOS to become uncoupled and produce superoxide that reacts with NO to form the toxic oxidant peroxynitrite and/or 2) causing excessive activation of the ornithine-polyamine pathway, thereby leading to polyamine oxidation and production of toxic oxidants. The global hypothesis of this project is that excessive activation of arginase 2 causes microglia/macrophage activation and neurovascular damage by inducing NOS uncoupling and/or excessive activation of the polyamine metabolic pathway. The proposed experiments will test and develop this working model by studies in a mouse model of traumatic optic nerve injury. Two specific aims are proposed. Aim 1 is to test the hypothesis that traumatic retinal injury is mediated by arginase-induced uncoupling of NOS and/or altered polyamine metabolism. These studies will determine the effects of arginase knockdown on microglia/macrophage activation, neurovascular degeneration and vascular function following optic nerve injury. The protective effects of arginase deletion on microglia/macrophage activation, inflammation and neurovascular damage will be examined in relation to NOS function, polyamine metabolism and their activity in producing ROS. Vasorelaxation and permeability barrier function will be determined by in vivo imaging. Arginase 2 deletion should limit microglia/macrophage activation and mitigate the neurovascular damage/dysfunction by normalizing NOS function, reducing polyamine oxidation and limiting oxidative stress and inflammation. Aim 2 is to perform preclinical studies for prevention and treatment of traumatic neurovascular injury. These studies we will determine and compare the treatment efficacy and safety of inhibiting arginase signaling and/or polyamine metabolism in limiting or preventing microglia/macrophage activation, inflammation and retinal neurovascular injury in the model of traumatic injury as explained for Aim 1. The beneficial effects of the treatments in preserving retinal structure and neuronal function will also be assessed using in vivo imaging and electroretingraphic recording. The expected outcomes include validation of the arginase/polyamine pathway as a novel target for therapeutic intervention to attenuate oxidative stress, inflammation and neurovascular degeneration and promote healthy repair following traumatic retinal injury. The impact of this work will be to provide a new understanding of the complex interactions between arginase, NOS and polyamine metabolism-associated inflammation and injury that will serve as a basis for development of novel therapeutic agents to treat traumatic retinal injury. Successful completion of this project is highly relevant to the mission of VA and to the health and well-being of veterans.

 描述（由申请人提供）： 本研究的长期目标是阐明导致创伤诱导的视网膜神经元和血管损伤的分子机制，并确定预防或逆转损伤和保护视力的新策略。缺乏对眼外伤损伤视网膜神经元和血管细胞的详细分子机制的理解代表了开发有效疗法的关键知识差距。因此，本研究的目的是 确定这些机制，并确定创新方法，以防止这种损害，改善功能结果，并减少从战场返回的退伍军人失明的风险。初步数据表明，缺血或创伤诱导的线粒体尿素水解酶2的激活通过增加氧化应激引起小胶质细胞/巨噬细胞激活、炎症和神经血管变性。过度活性的鸟氨酸酶可以通过以下方式增加氧化应激：1）减少一氧化氮合酶（NOS）产生NO所需的L-精氨酸供应，从而导致NOS变得解偶联并产生超氧化物，超氧化物与NO反应形成毒性氧化剂过氧亚硝酸盐，和/或2）导致鸟氨酸-多胺途径的过度活化，从而导致多胺氧化和毒性氧化剂的产生。该项目的总体假设是，过氧化氢酶2的过度活化通过诱导NOS解偶联和/或多胺代谢途径的过度活化而引起小胶质细胞/巨噬细胞活化和神经血管损伤。所提出的实验将通过在创伤性视神经损伤的小鼠模型中的研究来测试和开发该工作模型。提出了两个具体目标。目的1是检验创伤性视网膜损伤是由NOS解偶联和/或多胺代谢改变介导的假说。这些研究将确定视神经损伤后，β-半乳糖苷酶敲低对小胶质细胞/巨噬细胞活化、神经血管变性和血管功能的影响。将检查与NOS功能、多胺代谢及其在产生ROS中的活性相关的腺苷酸酶缺失对小胶质细胞/巨噬细胞活化、炎症和神经血管损伤的保护作用。将通过体内成像确定血管舒张和渗透性屏障功能。精氨酸酶2缺失应限制小胶质细胞/巨噬细胞活化，并通过使NOS功能正常化、减少多胺氧化和限制氧化应激和炎症来减轻神经血管损伤/功能障碍。目的二是进行创伤性神经血管损伤的临床前研究。在这些研究中，我们将确定和比较抑制腺苷酸酶信号传导和/或多胺代谢在创伤性损伤模型中限制或预防小胶质细胞/巨噬细胞活化、炎症和视网膜神经血管损伤的治疗功效和安全性，如目的1所解释的。还将使用体内成像和视网膜电图记录来评估治疗在保留视网膜结构和神经元功能方面的有益效果。预期的结果包括验证的辅酶A酶/多胺途径作为一种新的治疗干预目标，以减轻氧化应激，炎症和神经血管变性，并促进健康的修复创伤性视网膜损伤后。这项工作的影响将是提供一个新的理解之间的复杂的相互作用的酶，NOS和多胺代谢相关的炎症和损伤，将作为一个基础，开发新的治疗药物来治疗创伤性视网膜损伤。该项目的成功完成与退伍军人事务部的使命以及退伍军人的健康和福祉密切相关。