Neuroinflammation in Wallerian Degeneration and Regeneration: Neutrophils Play a Primary Role as Phagocytes

华勒变性和再生中的神经炎症：中性粒细胞作为吞噬细胞发挥主要作用

基本信息

批准号：
10447730
负责人：
RICHARD E ZIGMOND
金额：
$ 50.03万
依托单位：
CASE WESTERN RESERVE UNIVERSITY
依托单位国家：
美国
项目类别：
财政年份：
2020
资助国家：
美国
起止时间：
2020-08-01 至 2025-06-30
项目状态：
未结题

来源：
https://reporter.nih.gov/project-details/10447730
关键词：
Acute Animal Model Anti-Inflammatory Agents Antibodies Attention Axon Axotomy B-Lymphocytes Blood Brain CCL2 gene CXCL1 gene CXCL2 gene Cells Demyelinating Diseases Demyelinations Disease Disease Progression Distal Electrons Electrophysiology (science)Enzyme-Linked Immunosorbent Assay Excision Experimental Autoimmune Neuritis Ganglia Genes Growth Guillain Barré Syndrome IL8RB gene Immune In Situ Hybridization Inflammatory Injury Interleukin-8B Receptor Knock-out Knockout Mice Label Lesion Measures Modeling Multiple Sclerosis Mus Myelin Myelin Proteins Natural regeneration Nerve Nerve Crush Nerve Degeneration Nerve Regeneration Nervous system structure Neural Conduction Neuraxis Neuroglia Neuroimmune Neurons Neuropathy Neutrophil Infiltration Neutrophilic Infiltrate Oils Pathologic Pathology Peripheral Peripheral Nervous System Peripheral Nervous System Diseases Phagocytes Phagocytosis Pharmacology Phenotype Play Population Process Proteins Public Health Recovery of Function Reporting Role Schwann Cells Spinal Cord Stains T-Lymphocyte Techniques Time Tissues Tolonium chloride Trauma Wallerian Degeneration Western Blotting Wild Type Mouse antagonist base cell type chemokine chemokine receptor experimental study improved indexing injured macrophage monocyte monocyte chemoattractant protein 1 receptor mouse model nerve transection nervous system disorder neuroinflammation neutralizing antibody neutrophil novel receptor regenerative relating to nervous system response sciatic nerve

项目摘要

Understanding the process of neural degeneration is important in order to understand the responses of the nervous system to injury and disease. A common model used in such studies is the distal segment of the sciatic nerve after nerve transection or crush. Following such a lesion, Wallerian degeneration occurs in which the distal segment of the nerve fragments and degenerates, and the resulting axonal and myelin debris are cleared away. Interestingly, while this process occurs rapidly in the peripheral nervous system (PNS), it is extremely slow in the central nervous system (CNS), and, partly because of this, regeneration is generally ineffective in the brain and spinal cord. It is widely believed that inflammatory macrophages (mφs) derived from blood-borne monocytes are required for the phagocytosis of axonal and myelin debris. Immune cells enter injured tissue in response to chemotactic cytokines or chemokines. A major population of monocytes infiltrates into the distal nerve after axotomy in response to the chemokine CCL2, which acts on monocytes via the chemokine receptor CCR2. In mice in which the gene for CCR2 is knocked out, CCR2+ monocytes do not enter the nerve. It was, therefore, very surprising when we found that the clearance of both myelin and axonal protein is normal in Ccr2 knockout mice. We subsequently found that an important reason for the normal clearance appears to be phagocytosis by neutrophils, an immune cell not previously implicated in Wallerian degeneration. In fact, although neutrophil actions in the CNS are beginning to be examined, for example in models of multiple sclerosis, there are almost no studies on their actions in the PNS. Our preliminary evidence using the neutrophil-depleting antibody anti- Ly6G suggests, but does not prove, that neutrophils directly phagocytose and metabolize myelin. We will examine this hypothesis by examining the clearance of myelin proteins by western blotting before and after neutrophil depletion and by co-labeling tissue with Oil Red O, a stain for myelin metabolites, and with cell type specific neutrophils antibodies. We have shown that after axotomy two neutrophil attracting chemokines are induced in the sciatic nerve, CXCL1 and CXCL2. To determine whether these chemokines and their receptor, CXCR2, are involved in neutrophil infiltration into the nerve, we will use neutralizing antibodies, pharmacological antagonists, and knockout mice. We will investigate also whether the involvement of neutrophils in Wallerian degeneration is important for subsequent regeneration. “Wallerian-like” degeneration occurs in several demyelinating neuropathies, and we will examine whether neutrophils play a role in this phenomenon. We will use a mouse model for Guillain Barré syndrome based on our recent finding that neutrophils enter into the sciatic nerve in this model. Following up on our unexpected findings of normal clearance of myelin in Ccr2 knockout mice, our experiments will examine the role of neutrophils in Wallerian degeneration and in a demyelinating disease. Given the known importance of Wallerian degeneration for nerve regeneration due to the removal of myelin proteins, our studies will suggest ways of improving regeneration in the PNS and perhaps in the CNS.

了解神经变性的过程对于理解神经元的反应非常重要此类研究中使用的常见模型是坐骨神经系统的远端部分。神经横断或挤压后，发生这种病变后，远端会发生华勒变性。神经片段断裂并退化，产生的轴突和髓鞘碎片被清除。暗示，虽然这个过程在周围神经系统（PNS）中发生得很快，但在中枢神经系统（CNS），部分原因是大脑的再生通常无效人们普遍认为炎症巨噬细胞（mφs）源自血源性单核细胞。免疫细胞响应于进入受损组织而吞噬轴突和髓磷脂碎片。趋化细胞因子或趋化因子的主要群体浸润到远端神经。响应趋化因子 CCL2 的轴索切断术，趋化因子 CCL2 通过趋化因子受体 CCR2 In 作用于单核细胞。 CCR2 基因被敲除的小鼠，CCR2+ 单核细胞不会进入神经。当我们发现 Ccr2 敲除中髓鞘质和轴突蛋白的清除均正常时，我们感到非常惊讶我们随后发现正常清除的一个重要原因似乎是吞噬作用。中性粒细胞，一种以前与沃勒变性无关的免疫细胞，事实上，尽管中性粒细胞。中枢神经系统的作用已经开始被研究，例如在多发性硬化症模型中，几乎有没有关于它们在三七总皂甙中的作用的研究。我们使用中性粒细胞消耗抗体抗-的初步证据。 Ly6G 表明，但并未证明，中性粒细胞直接吞噬和代谢髓磷脂。通过免疫印迹检查前后髓磷脂蛋白的清除情况来检验这一假设中性粒细胞耗竭，并用油红 O（髓鞘代谢物染色剂）和细胞类型对组织进行联合标记我们已经证明，轴切术后，有两种中性粒细胞吸引趋化因子。在坐骨神经中诱导 CXCL1 和 CXCL2，以确定这些趋化因子及其受体是否存在。 CXCR2，参与中性粒细胞浸润神经，我们将使用中和抗体，药理我们还将研究中性粒细胞是否参与华勒氏病。 “华勒样”变性发生在多种脱髓鞘神经病，我们将检查中性粒细胞是否在这种现象中发挥作用。基于我们最近发现中性粒细胞进入坐骨神经节，使用吉兰巴利综合征小鼠模型跟进我们在 Ccr2 敲除中髓鞘质清除正常的意外发现。小鼠，我们的实验将检查中性粒细胞在沃勒变性和脱髓鞘中的作用鉴于已知沃勒变性对于神经再生的重要性，这是由于去除了神经。髓磷脂蛋白，我们的研究将提出改善三七总神经系统（也许还有中枢神经系统）再生的方法。