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: 9206410
• 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/9206410
• 关键词: 3-nitrotyrosine; ARG2 gene; 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; Polyamines; Prevention; Production; Research; Retina; Retinal; Retinal Degeneration; 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; combat; effective therapy; experimental study; functional outcomes; improved; in vivo; in vivo imaging; inhibitor/antagonist; injured; innovation; knock-down; mouse model; neurovascular; neurovascular injury; new therapeutic target; novel strategies; novel therapeutics; operation; oxidation; polyamine oxidase; preclinical study; prevent; protective effect; public health relevance; repaired; retinal damage; retinal neuron; treatment effect

 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)： 这项研究的长期目标是描绘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。对眼外伤损害视网膜神经元和血管细胞的详细分子机制缺乏了解，这是开发有效治疗方法的关键知识缺口。因此，这项研究的目标是 确定这些机制并确定创新的方法，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、精氨酸酶2的激活通过增加氧化应激而导致小胶质细胞/巨噬细胞的激活、炎症和神经血管变性。过度活跃的精氨酸酶可通过以下方式增加氧化应激：1)减少一氧化氮合酶产生NO所需的L-精氨酸供应，从而导致一氧化氮合酶解偶联，产生超氧化物与NO反应形成有毒氧化剂过氧亚硝酸盐；和/或2)导致鸟氨酸-多胺途径过度激活，从而导致多胺氧化和有毒氧化剂的产生。该项目的总体假设是，精氨酸酶2的过度激活通过诱导一氧化氮合酶解偶联和/或多胺代谢途径的过度激活而导致小胶质细胞/巨噬细胞激活和神经血管损伤。拟议的实验将通过研究创伤性视神经损伤的小鼠模型来测试和开发这一工作模型。提出了两个具体目标。目的1验证创伤性视网膜损伤是由精氨酸酶诱导的一氧化氮合酶去偶联和/或多胺代谢改变所介导的假说。这些研究将确定精氨酸酶基因敲除对视神经损伤后小胶质细胞/巨噬细胞激活、神经血管变性和血管功能的影响。精氨酸酶缺失对小胶质细胞/巨噬细胞激活、炎症和神经血管损伤的保护作用将与一氧化氮合酶功能、多胺代谢及其产生ROS的活性有关。血管松弛和通透性屏障功能将通过活体成像来确定。精氨酸酶2缺失可能通过使一氧化氮合酶功能正常化，减少多胺氧化，限制氧化应激和炎症，从而限制小胶质细胞/巨噬细胞的激活，减轻神经血管损伤/功能障碍。目的2为预防和治疗创伤性神经血管损伤进行临床前研究。在这些研究中，我们将确定和比较抑制精氨酸酶信号转导和/或多胺代谢在限制或预防小胶质/巨噬细胞激活、炎症和视网膜神经血管损伤方面的治疗效果和安全性，正如目标1所解释的那样。这些治疗方法在保护视网膜结构和神经功能方面的有益效果也将通过活体成像和视网膜电描记术进行评估。预期的结果包括确认精氨酸酶/多胺途径作为治疗干预的新靶点，以减轻氧化应激、炎症和神经血管退化，并促进外伤性视网膜损伤后的健康修复。这项工作的影响将是对精氨酸酶、一氧化氮合酶和多胺代谢相关的炎症和损伤之间的复杂相互作用提供新的理解，这将成为开发治疗创伤性视网膜损伤的新型治疗药物的基础。这一项目的成功完成与退伍军人管理局的使命以及退伍军人的健康和福祉密切相关。