Immune-mediated Neuroprotection of Retinal Ganglion Cells

描述（由申请人提供）：先天免疫系统由细胞和分子组成，这些细胞和分子构成对损伤和感染的非抗原特异性反应，包括巨噬细胞、树突状细胞和pmn。中枢神经系统的先天免疫反应，部分由小胶质细胞代表，已被证明影响神经损伤的结果，基于神经保护作用的证据，以及在神经变性和病理中的作用。很可能先天免疫在视网膜中起着类似的作用。先天免疫反应促进适应性免疫反应，并可由适应性免疫、抗原特异性免疫臂调节，提高了利用免疫的这两个方面来控制神经组织对损伤反应的可能性。自20世纪90年代末提出具有神经自身抗原特异性的T细胞是神经保护的重要组成部分以来，对神经损伤产生更有利结果的可能性受到了极大的关注。这个想法有几个吸引人的原因，包括可能促进对视网膜有巨大健康影响的眼睛慢性疾病（青光眼、黄斑变性、糖尿病等）的神经保护。然而，关于免疫系统和神经系统如何相互作用的明确证据仍然难以捉摸，关键假设仍然需要实验验证。此外，新的假设正在发展，可能会改变这些范式。我们利用转基因和基因敲除小鼠进行了与视网膜自身免疫和免疫耐受相关的研究，发现了视网膜损伤应答的新成分。这些小鼠和策略可以迅速应用于神经保护的研究，并用于检测免疫在视网膜稳态和损伤反应中的作用，与实验性自身免疫性疾病分开。这些小鼠为确定免疫在神经保护/神经变性中的作用带来了新的机会。在这个建议的问题是基于初步结果，表明早期参与树突状细胞损伤视网膜神经节细胞。实验集中于先天免疫树突状细胞对神经退行性疾病/保护的可能贡献，并测试它们在视网膜抗原特异性T细胞聚焦于神经保护而不是疾病中的作用。利用青光眼视网膜神经节细胞死亡的视神经挤压模型，第一个Aim验证了我们的假设，即树突状细胞有助于视网膜稳态。我们的问题是：1)如果树突状细胞，而不是小胶质细胞，是视网膜损伤的第一个关键反应者，2)它们是否有助于神经保护，以及3)它们如何与受损的视网膜神经节细胞交流。由于树突状细胞是重要的抗原呈递细胞，第二个目的是研究适应性免疫反应对神经保护的招募，并提出以下问题：1)树突状细胞是否将T细胞招募到损伤处，2)哪种T细胞群对视网膜神经节细胞的存活或丧失很重要，以及3)T细胞的Ag特异性是否重要。

DESCRIPTION (provided by applicant): The innate immune system is comprised of cells and molecules that make up non-antigen specific responses to injury and infection, and includes macrophages, dendritic cells, and PMNs. Innate immune responses in the CNS, represented in part by microglia, have been shown to affect the outcome of neural injuries based on evidence for neuroprotective roles, as well as roles in neurodegeneration and pathology. It is likely that innate immunity plays similar roles in retina. The innate immune response promotes adaptive immune responses, and can be regulated by the adaptive, antigen specific arm of immunity, raising the possibility that these two facets of immunity could be exploited to control the neural tissue response to injury. The possibility of producing more favorable outcomes to neural injuries has received significant attention since the late 1990s when it was proposed that T cells with specificity for neural self-antigens were an important part of neuroprotection. The idea is attractive for several reasons, including the possibility to promote neuroprotection in chronic diseases of the eye that have enormous health impacts on the retina (glaucoma, macular degeneration, diabetes, etc.). However, definitive evidence on how the immune system and nervous system interface remains elusive, and key hypotheses still require experimental validation. Further, new hypotheses are being developed that may change these paradigms. We have been using transgenic and knockout mice for studies related to retinal autoimmunity and immunologic tolerance, and found a new component in the response to retinal injury. These mice and strategies could be rapidly applied to the study of neuroprotection, and used to examine the role of immunity in retinal homeostasis and response to injury, separate from experimental autoimmune disease. The mice bring a fresh opportunity to define the role of immunity in neuroprotection/neurodegeneration. The questions in this proposal are based on preliminary results that suggest the early participation of dendritic cells following injury to retinal ganglion cells. The experiments concentrate on the possible contributions of dendritic cells of innate immunity to neurodegenerative disease/protection, and test their role in focusing retinal antigen specific T cells on neuroprotection, rather than disease. Using the optic nerve crush model for retinal ganglion cell death in glaucoma, the first Aim tests our hypothesis that dendritic cells contribute to retinal homeostasis. We ask: 1) if dendritic cells, rather than microglia, are the first critical responders to retinal injury, 2) do they contribute to neuroprotection, and 3) how they communicate with injured retinal ganglion cells. Since dendritic cells are important antigen presenting cells, the second Aim examines recruitment of an adaptive immune response into neuroprotection, and asks: 1) do the dendritic cells recruit T cells to the injury, 2) what population of T cells is important to retinal ganglion cell survival or loss, and 3) does the Ag- specificity of the T cells matter. PUBLIC HEALTH RELEVANCE: Injuries and diseases that lead to neurodegeneration afflict an ever-growing portion of the human population. The outcomes of these neurodegenerative processes range from mildly debilitating to deadly and include glaucoma, age-related macular degeneration, diabetic retinopathy, Alzheimer's disease, stroke, traumatic injuries, infectious diseases, and many other less common causes. Since aging is a factor in many of these diseases, their impact will increase, as the average age of the population increases. Progress toward understanding the fundamental mechanisms of neuroprotection is critical.