Inflammation and Degeneration of Optic Nerve in EAE

描述（由申请人提供）：视神经损伤导致的视力受损是多发性硬化症（MS）患者最常见的症状之一。MS相关的视神经损伤是由于自身反应性T细胞和其他免疫细胞的流入。炎症过程被认为有助于脱髓鞘、轴突变性以及少突胶质细胞和视网膜神经节细胞（RGC）的损失。了解EAE视神经变性的病理生理学对开发恢复视功能的药物具有潜在的治疗意义。 在刘易斯大鼠中，使用MS、实验性过敏性脑脊髓炎（EAE）的动物模型证明视神经中钙蛋白酶（一种钙（Ca 2+）依赖性蛋白酶）的活性和表达增加，这暗示钙蛋白酶在EAE中的视神经损伤中的作用。由于炎症的确切时间以及视神经中细胞和轴突损伤的机制尚未完全了解，因此预防炎症和导致轴突和细胞损伤的分子事件的潜力可能会改善和恢复功能。我们假设钙蛋白酶介导的自身反应性T细胞的活化和免疫细胞浸润到CNS中将导致由于炎症导致的视觉功能丧失，从而导致EAE视神经中的轴突和少突胶质细胞损伤，随后可能在疾病的临床症状之前发生RGC的丧失。一个必然的假设是，在激发后的不同时间点抑制钙蛋白酶将通过预防外周和视神经中的炎症来恢复视觉功能，并在视神经损伤开始后改善神经变性。数据表明，Ca 2+内流，钙蛋白酶的表达，轴突损伤，细胞死亡，视网膜损伤的EAE视神经与疾病发作前的几个参数的影响增加。与未治疗的EAE动物相比，用钙蛋白酶抑制剂治疗减少了免疫细胞浸润、钙蛋白酶表达、细胞死亡和视网膜损伤，导致视觉反应改善。体外干扰素（IFN？）诱导的神经胶质细胞中的钙蛋白酶活化和MBP特异性T细胞上清液降解MBP。（1）确定EAE动物视神经炎症反应、Ca ~（2+）内流、Ca ~（2+）依赖性事件、细胞死亡和轴突/髓鞘变性的时间，并检查RGC状态与EAE动物攻击后视觉功能障碍的相关性;（2）研究钙蛋白酶抑制剂治疗是否会通过改变免疫臂来恢复视觉功能。（T细胞活化，免疫细胞浸润到视神经中）和/或神经变性臂（细胞死亡，轴突损伤）;和（3）检测钙蛋白酶抑制剂在体外对RGCs的功能的保护作用。炎性细胞因子或与来自活化的MBP特异性T细胞的上清液孵育。了解视神经损伤的过程和时间将进一步发展治疗策略，以最好地恢复MS中视神经变性引起的损伤。 公共卫生相关性：视神经损伤导致视力受损是多发性硬化症（MS）患者最常见的症状之一。由于免疫细胞的流入引起的视神经的MS相关炎症被认为有助于导致视力受损的缺陷，包括脱髓鞘、轴突变性和视网膜神经节细胞（RGC）和少突胶质细胞的损失。了解炎症和神经退行性事件导致视神经损伤的机制可能对开发保护细胞、保护轴突和髓鞘的药物具有重要的潜在治疗意义，从而改善视力并最终延缓MS的发展。

DESCRIPTION (provided by applicant): Impaired vision due to optic nerve damage is one of the most common presenting symptoms of patients with multiple sclerosis (MS). MS-associated optic nerve damage is due to an influx of auto-reactive T cells and other immune cells. The inflammatory process is thought to contribute to demyelination, axonal degeneration, and loss of oligodendrocytes and retinal ganglion cells (RGCs). Understanding the pathophysiology of optic nerve degeneration in EAE has potential therapeutic implications to develop agents that restore visual function. Demonstration of increased activity and expression of calpain, a calcium (Ca2+)-dependent protease, in optic nerve using an animal model of MS, experimental allergic encephalomyelitis (EAE), in Lewis rats has implied a role for calpain in optic nerve damage in EAE. Since the precise timing of inflammation and mechanisms of cell and axon damage in optic nerve are not fully understood, the potential to prevent inflammation and molecular events that lead to axonal and cell damage, may improve and restore function. We hypothesize that calpain-mediated activation of auto-reactive T cells and immune cell infiltration into the CNS will result in loss of visual function due to inflammation leading to axon and oligodendrocyte damage in EAE optic nerve with subsequent loss of RGCs which may occur prior to clinical symptoms of disease. A corollary hypothesis is that inhibiting calpain at different time-points following challenge will restore visual function by preventing inflammation in the periphery and in optic nerve, and ameliorate neurodegeneration after damage to the optic nerve have begun. Data indicate that Ca2+ influx, calpain expression, axonal damage, cell death, and retinal damage are increased in EAE optic nerve with several parameters affected before disease onset. Treatment with calpain inhibitors reduced immune cell infiltration, calpain expression, cells death, and retinal damage, resulting in improved visual responses compared to untreated EAE animals. In vitro interferon (IFN?) induced calpain activation in glial cells and MBP-specific T cell supernatant degraded MBP. The following specific aims have been designed to test these hypotheses: (1) determine the timing of inflammatory responses, Ca2+ influx, Ca2+-dependent events, cell death, and axonal/myelin degeneration in EAE optic nerve and examine the status of RGCs in correlation with visual dysfunction in EAE animals following challenge; (2) investigate whether treatment with calpain inhibitors will restore visual function by altering the immune arm (T cell activation, immune cell infiltration into optic nerve) and/or the neurodegenerative arm (cell death, axonal damage) in acute EAE, as compared to vehicle treated animals; and (3) examine the effects of calpain inhibitors in preserving and protecting function of RGCs in vitro when subjected to pro-inflammatory cytokines or incubated with supernatant from activated MBP- specific T cells. Understanding the process and timing of optic nerve damage will further the development of treatment of strategies to best restore the impairment caused by optic nerve degeneration in MS. PUBLIC HEALTH RELEVANCE: Damage to the optic nerve resulting in impaired vision is one of the most common symptoms of patients with multiple sclerosis (MS). MS-associated inflammation of the optic nerve due to an influx of immune cells is thought to contribute to deficits leading to impaired vision, including demyelination, axonal degeneration, and loss of retinal ganglion cells (RGCs) and oligodendrocytes. Understanding the mechanisms by which inflammatory and neurodegenerative events contribute to optic nerve damage may have important and potentially therapeutic implications for developing agents that protect cells, preserve axons and myelin, and thus, improve vision and ultimately retard the development of MS.