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：
10219366
负责人：
RICHARD E ZIGMOND
金额：
$ 50.02万
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/10219366
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 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了解神经系统受伤和疾病。此类研究中使用的一个常见模型是坐骨神经的远端段神经横断或粉碎后神经。在这种病变之后，发生沃勒式变性，其中不同神经片段和退化的片段以及所得的轴突和髓磷脂碎片被清除。有趣的是，尽管此过程迅速发生在外周神经系统（PNS）中，但它的速度极慢。中枢神经系统（CNS），部分因此，再生在大脑中通常无效和脊髓。人们普遍认为，源自血传播单核细胞的炎症性巨噬细胞（MφS）免疫细胞响应于趋化细胞因子或趋化因子。大量的单核细胞浸润到远端神经之后轴突切开术，响应于趋化因子CCL2，该趋化因子通过趋化因子受体CCR2作用于单核细胞。在 CCR2基因的小鼠被淘汰，CCR2+单核细胞不进入神经。因此，是当我们发现髓磷脂和轴突蛋白的清除率在CCR2敲除中均正常时感到非常惊讶老鼠。随后，我们发现，正常清除率的一个重要原因似乎是通过中性粒细胞是一种以前未在沃勒（Wallerian）变性中实施的免疫核物。实际上，虽然中性粒细胞中枢神经系统中的动作正在开始检查，例如，在多发性硬化症的模型中，几乎存在没有研究他们在PNS中的行为。我们使用中性粒细胞缺乏抗体抗体的初步证据 LY6G建议但没有证明中性粒细胞直接吞噬糖细胞并代谢髓磷脂。我们将通过在蛋白质上和之后检查髓磷脂蛋白的清除来检查这一假设中性粒细胞耗尽并通过与油红O共同标记组织，髓磷脂代谢产物的染色以及细胞类型特异性嗜中性粒细胞抗体。我们已经表明，在轴突切开术后两个嗜中性粒细胞吸引趋化因子是在坐骨神经，CXCL1和CXCL2中诱导。为了确定这些趋化因子及其接收器是否 CXCR2参与中性粒细胞浸润到神经中，我们将使用中和抗体，药物对手和淘汰小鼠。我们还将研究中性粒细胞参与沃勒里亚人退化对于随后的再生很重要。 “类似沃勒的”变性发生在几个神经病脱髓鞘，我们将检查神经磷是否在这种现象中起作用。我们将根据我们最近的发现，中性粒细胞进入坐骨神经在此模型中的神经。跟随我们意外发现CCR2敲除髓磷脂正常清除的发现小鼠，我们的实验将检查中性粒细胞在沃勒式变性和脱髓鞘中的作用疾病。鉴于由于去除而已知的沃勒利变性对神经再生的重要性髓磷脂蛋白，我们的研究将提出改善PNS甚至中枢神经系统再生的方法。