Mechanisms underlying macrophage action in nerve regeneration and degeneration

巨噬细胞在神经再生和变性中作用的机制

• 批准号: 9282327
• 负责人: RICHARD E ZIGMOND
• 金额: $ 47.31万
• 依托单位: CASE WESTERN RESERVE UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2016
• 资助国家: 美国
• 起止时间: 2016-06-01 至 2021-05-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/9282327
• 关键词: AVIL gene; Acute; Affect; American; Animals; Autoimmune Process; Axon; Axotomy; CCL2 gene; Cells; Chemotherapy-Oncologic Procedure; Clinical; Conditioned Culture Media; Diabetes Mellitus; Distal; Environment; Evaluation; Ganglia; Gene Expression; Generations; Genes; Genetic; Growth; Growth Factor; HIV; Hereditary Disease; In Situ Hybridization; Infiltration; Injury; Intervention; Knock-out; LIF gene; Lesion; Macrophage Colony-Stimulating Factor Receptor; Measures; Mediating; Medical; Microfluidics; Modeling; Molecular; Mus; Mutant Strains Mice; Myelin; Natural regeneration; Nerve; Nerve Degeneration; Nerve Regeneration; Neurites; Neuroglia; Neuroimmune; Neurons; Peripheral; Peripheral Nervous System; Peripheral Nervous System Diseases; Peripheral nerve injury; Phagocytes; Phenotype; Process; Reaction; Recovery; Schwann Cells; Signal Pathway; Site; Spinal Ganglia; Surgical incisions; Testing; Thinking; Trauma; Uncertainty; Virus; Wallerian Degeneration; Work; afferent nerve; axon growth; cell type; chemokine; chemokine receptor; chemotherapy; conditioning; cytokine; design; effective therapy; ganglion cell; hereditary neuropathy; improved; in vivo; in vivo regeneration; inhibitor/antagonist; injured; insight; knock-down; macrophage; monocyte; monocyte chemoattractant protein 1 receptor; neurite growth; neuroinflammation; neuronal cell body; novel strategies; peripheral nerve regeneration; permissiveness; regenerative; response; sciatic nerve; transcriptome sequencing

Peripheral nerve injury is common and occurs due to a variety of causes including trauma, diabetes, cancer chemotherapy, autoimmune reactions, and genetic disorders. Although peripheral neurons are capable of regenerating, this process is generally incomplete. It is therefore crucial to determine ways in which regener- ation can be enhanced. Macrophages are thought to promote peripheral nerve regeneration after an acute injury due to their accumulation in the distal nerve where they phagocytize axonal debris and myelin thereby creating an environment through which axons can grow. In addition, macrophages secrete cytokines that trigger growth factor synthesis in non-neuronal cells in the nerve. The absence of these actions has been assumed to be the basis for the slow regeneration that occurs in the slowly degenerating Wlds mouse. How- ever, it has been known for 20 years. In part due to our studies. that there is a second, distinct, site of mac- rophage accumulation after injury, namely, peripheral ganglia such as dorsal root ganglia (DRGs) where the axotomized cell bodies reside. What has remained unknown is what function these macrophages subserve. Recent studies from our lab represent a major advance in answering this question. Work with two mutant mouse strains, a knockout for the chemokine receptor CCR2 and the Wlds mice led to the hypothesis that macrophage accumulation in ganglia is required for the occurrence of the conditioning lesion (CL) response, the response in which neurite outgrowth after a lesion is increased as a consequence of an earlier condition- ing lesion. This application is designed to test the following overall model: macrophages brought into the DRG by the chemokine CCL2 trigger the expression of regeneration associated genes (RAGs) via the secretion of cytokines around axotomized cell bodies and this promotes the CL response and regen- eration in addition to any effects macrophages have on the distal nerve. To establish beyond doubt that CCL2-dependent macrophage accumulation and the CCL2-dependent CL response are causally related, we will use an inhibitor of colony stimulating factor 1 receptors to deplete circulating monocytes. To deter- mine whether macrophages act directly on neuronal cell bodies, we will use microfluidic chambers in which a neuron’s cell body and axon can be separated. Gene expression using RNAseq will be compared after ax- otomy in CCRs -/- and wild type animals to determine which axotomy-induced genes are dependent on mac- rophage accumulation. Since we have shown that Wallerian degeneration is normal in CCR2 -/- mice but monocyte infiltration into DRGs is blocked, these animals will allow us to determine whether macrophage accumulation in DRGs is required for sensory nerve regeneration in vivo. Using these novel approaches, we will examine the mechanisms underlying the relationship between macrophage accumulation near axoto- mized cell bodies and axonal growth. Emphasizing ganglia, unexplored sites of neuroinflammation, repre- sents a paradigm shift from the traditional view that focuses on macrophage effects on the distal nerve.

周围神经损伤很常见，由多种原因引起，包括外伤、糖尿病、癌症 化疗、自身免疫反应和遗传性疾病虽然外周神经元有能力。 再生，这个过程通常是不完整的，因此确定再生的方式至关重要。 巨噬细胞被认为可以促进急性周围神经再生。 由于它们在远端神经中积聚而造成损伤，从而吞噬轴突碎片和髓磷脂 创造轴突生长的环境此外，巨噬细胞分泌细胞因子。 触发神经中非神经元细胞的生长因子的合成一直缺乏这些作用。 被认为是缓慢退化的 Wlds 小鼠中发生缓慢再生的基础。 20 年前，我们就已经知道存在第二个独特的 Mac 站点。 损伤后噬菌体的积累，即周围神经节，例如背根神经节（DRG） 目前尚不清楚的是这些巨噬细胞具有什么功能。 我们实验室最近的研究代表了回答这个问题的重大进展。 小鼠品系、趋化因子受体 CCR2 敲除和 Wlds 小鼠导致了以下假设： 巨噬细胞在神经节中的积累是条件损伤（CL）反应发生所必需的， 由于早期病症而导致病变后神经突生长增加的反应- 该应用程序旨在测试以下整体模型：将巨噬细胞带入体内。 趋化因子 CCL2 的 DRG 通过以下途径触发再生相关基因 (RAG) 的表达 细胞因子在轴突细胞体周围分泌，这促进了 CL 反应和再生 除了巨噬细胞对远端神经的影响之外，还可以毫无疑问地确定这一点。 CCL2 依赖性巨噬细胞积累和 CCL2 依赖性 CL 反应是因果相关的， 我们将使用集落刺激因子 1 受体抑制剂来消除循环单核细胞。 为了确定巨噬细胞是否直接作用于神经元细胞体，我们将使用微流体室，其中 神经元的细胞体和轴突可以在ax-后使用RNAseq分离基因表达。 在 CCRs -/- 和野生型动物中进行切开术，以确定哪些轴切术诱导的基因依赖于 mac- 因为我们已经证明华勒变性在 CCR2 -/- 小鼠中是正常的，但 单核细胞浸润到 DRG 被阻止，这些动物将使我们能够确定巨噬细胞是否 体内感觉神经再生需要 DRG 中的积累，我们使用这些新方法。 将检查轴突附近巨噬细胞积累之间关系的潜在机制 强调神经节、未探索的神经炎症部位、repre- 的细胞体和轴突生长。 与关注巨噬细胞对远端神经影响的传统观点相比，范式发生了转变。