Muller glial cell pathophysiology during glaucoma onset

青光眼发病期间的 Muller 胶质细胞病理生理学

• 批准号: 10591936
• 负责人: Sidney P Kuo
• 金额: $ 23.25万
• 依托单位: UNIVERSITY OF MINNESOTA
• 依托单位国家: 美国
• 财政年份: 2023
• 资助国家: 美国
• 起止时间: 2023-03-01 至 2025-02-28
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/10591936
• 关键词: Affect; Area; Axon; Blindness; Calcium Signaling; Cell Death; Cell membrane; Cell physiology; Cells; Cellular Morphology; Cellular Structures; Cessation of life; Chronic; Contrast Sensitivity; Coupled; Dendrites; Diagnosis; Disease; Disease Progression; Early identification; Electrophysiology (science); Event; Eye; Eye diseases; Family; Fluorescence Microscopy; Functional disorder; Glaucoma; Gliosis; Glutamate Receptor; Glutamate Transporter; Glutamates; Goals; Health; Image; Injections; Inner Plexiform Layer; Knowledge; Label; Light; Link; Measures; Mechanics; Membrane; Microscopy; Microspheres; Modeling; Molecular; Morphology; Muller' s cell; N-Methylaspartate; Nerve Degeneration; Neurodegenerative Disorders; Neuroglia; Neurons; Ocular Hypertension; Onset of illness; Output; Pathologic; Pattern; Physiologic Intraocular Pressure; Physiology; Play; Positioning Attribute; Predisposition; Preparation; Process; Regulation; Research; Retina; Retinal Diseases; Retinal Ganglion Cells; Risk Factors; Role; Shapes; Signal Transduction; Site; Synapses; Techniques; Testing; Tissue Fixation; Tissues; Traction; Transgenic Mice; Viral; Withdrawal; Work; cell type; designer receptors exclusively activated by designer drugs; excitotoxicity; experimental study; extracellular; fluorescence imaging; glutamatergic signaling; high intraocular pressure; hypertensive; insight; novel; optical imaging; patch clamp; pressure; receptor-mediated signaling; response; retinal ganglion cell degeneration; retinal neuron; selective expression; synaptic function; two-photon; uptake; visual stimulus

PROJECT SUMMARY The goal of this proposal is to understand how glial cell pathophysiology contributes to disease progression in glaucoma, a neurodegenerative eye disease characterized by dysfunction and death of retinal ganglion cells (RGCs), the output neurons of the retina. Elevated intraocular pressure (IOP) is the most common risk factor for glaucoma, yet the mechanisms linking high IOP and RGC loss remain poorly understood. Here, we focus on an important but previously unexamined aspect of disease progression: how early structural remodeling of Müller glial cells contributes to degeneration of RGCs. In glaucoma, as in other retinal diseases, Müller cells undergo a variety of molecular and morphological changes referred to as reactive gliosis. However, little is known regarding how Müller cells respond to ocular hypertension early in disease or how gliosis leads to RGC degeneration. We will use a combination of optical imaging, transgenic mice, viral techniques, and patch-clamp electrophysiology in an ex vivo eyecup preparation to fill these gaps in our knowledge. Aberrant Ca2+ signaling during disease onset may be an important upstream event that occurs prior to overt signs of Müller cell gliosis. In Aim 1A, we will test the hypothesis, suggested by our preliminary findings, that elevated pressure induces excessive Ca2+ signaling in Müller cell peri-synaptic processes within the inner plexiform layer (IPL) of the retina. We will use two-photon (2P) microscopy to compare Ca2+ signals in Müller glia in eyes with normal pressure vs. eyes in which IOP has been chronically elevated in a microbead occlusion model of glaucoma. In Aim 1B, we will directly test whether changes in Ca2+ signaling can drive morphological changes in Müller cells by selectively manipulating Müller cell intracellular [Ca2+]. Experiments in Aim 2A will use the microbead occlusion model and 2P imaging of fluorescently labeled Müller glia and RGCs to investigate whether ocular hypertension alters the physical relationship between Müller glial fine processes and RGC dendrites. In our preliminary work examining the morphology of Müller cells in tissue from eyes with chronically elevated IOP, we found that Müller cell processes retract within specific sublayers of the IPL. We will test the hypothesis, suggested by these preliminary findings, that Müller cell processes selectively withdraw from certain RGC subtypes soon after onset of ocular hypertension. An important function of Müller cell peri-synaptic processes is to regulate extracellular glutamate near synapses. Withdrawal of Müller glia could contribute importantly to disease progression by promoting RGC death via excitotoxic damage. Experiments in Aim 2B will examine this possibility by using two-photon Ca2+ imaging to test the hypothesis that elevated IOP increases light-evoked N-methyl-D-aspartate-type glutamate receptor activity in the dendrites of specific RGC subtypes. In both Aims, we will focus specifically on early-stage disease by conducting experiments within the first 1-2 weeks after IOP elevation. By identifying pathophysiological changes in Müller cells that occur early in disease progression, this work will help reveal novel ways to diagnose and treat glaucoma before RGC degeneration leads to irreversible vision loss.

项目总结 这项建议的目标是了解胶质细胞病理生理学如何在疾病进展中起作用 青光眼，一种以视网膜神经节细胞功能障碍和死亡为特征的神经退行性眼病 视网膜的输出神经元(RGCs)。高眼压(IOP)是最常见的危险因素 青光眼，然而，高眼压和RGC丢失之间的联系机制仍然知之甚少。在这里，我们重点介绍一种 疾病进展的重要但以前未被研究的方面：穆勒早期结构重塑 胶质细胞参与了视网膜节细胞的变性。在青光眼中，就像在其他视网膜疾病中一样，穆勒细胞经历了 各种分子和形态变化称为反应性胶质细胞增多症。然而，人们对此知之甚少。 在疾病早期，Müler细胞如何对高眼压做出反应，或胶质细胞增生症如何导致RGC退化。我们 将使用光学成像、转基因小鼠、病毒技术和膜片钳电生理学的组合 在体外眼科准备填补这些空白的我们的知识。疾病过程中的异常钙信号 发病可能是一个重要的上游事件，发生在Müler细胞胶质细胞增生的明显迹象之前。在目标1A中，我们 将检验我们的初步发现所提出的假设，即压力升高会导致过量的钙离子 视网膜内丛状层(IPL)内Müler细胞突触周围突触的信号传递。我们将使用 双光子(2P)显微镜观察正常眼压与正常眼压眼Müler神经胶质细胞内钙信号的比较 在微珠阻塞的青光眼模型中，该模型的眼压已经慢性升高。在目标1B中，我们将直接 检测Ca~(2+)信号的变化是否可以选择性地驱动Müller细胞的形态变化 操纵Müler细胞内[Ca~(2+)]。Aim 2A中的实验将使用微珠遮挡模型和 2P成像研究高眼压是否改变Müler神经胶质细胞和RGCs Müler神经胶质细突起与RGC树突的物理关系在我们的前期工作中审查 慢性高眼压眼组织中Müler细胞的形态观察 进程在IPL的特定子层内撤回。我们将检验假设，由这些初步建议 结果发现，在眼部发病后不久，Müler细胞突起选择性地退出某些RGC亚型 高血压。Müler细胞突触周围突触的一个重要功能是调节细胞外谷氨酸 在突触附近。Müller胶质细胞的退出可能通过促进RGC而在疾病进展中发挥重要作用 通过兴奋性毒性损伤致死。目标2B中的实验将通过使用双光子钙离子来检验这种可能性 成像检验高眼压增加光诱导的N-甲基-D-天冬氨酸型谷氨酸的假说 特定RGC亚型树突中的受体活性。在这两个目标中，我们将特别关注早期阶段 在眼压升高后的头1-2周内进行实验。通过识别 在疾病进展早期发生的Müler细胞的病理生理变化，这项工作将有助于揭示 在RGC变性导致不可逆转的视力丧失之前诊断和治疗青光眼的新方法。