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.

周围神经损伤是常见的，并且由于各种原因而发生，包括创伤、糖尿病、癌症 化疗、自身免疫反应和遗传疾病。尽管外周神经元能够 再生，这个过程通常是不完整的。因此，至关重要的是确定再生剂- 可以增强。巨噬细胞被认为可以促进周围神经在急性损伤后的再生。 损伤是由于它们在远端神经中的积累，在那里它们吞噬轴突碎片和髓磷脂， 创造一个轴突生长的环境。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合成。由于没有采取这些行动， 假设这是在缓慢退化的Wlds小鼠中发生的缓慢再生的基础。怎么-- 它已经被知道了20年。部分原因是我们的研究。有第二个，不同的，MAC的网站- 损伤后的噬菌体积聚，即外周神经节，如背根神经节（DRG），其中噬菌体积聚， 轴突切断的细胞体存在。目前尚不清楚这些巨噬细胞的功能是什么。 我们实验室最近的研究代表了回答这个问题的重大进展。与两个突变体合作 小鼠品系、趋化因子受体CCR 2敲除小鼠和Wlds小鼠导致了这样的假设， 巨噬细胞在神经节中的积累是发生条件性损伤（CL）反应所必需的， 损伤后神经突生长增加的反应是早期条件的结果- ing病变。该应用程序旨在测试以下整体模型： 趋化因子CCL 2通过激活DRG，触发再生相关基因（RAGs）的表达。 轴突切断的细胞体周围分泌细胞因子，这促进了CL反应和再生。 除了巨噬细胞对远端神经的任何影响外，毫无疑问地证明 CCL 2依赖性巨噬细胞蓄积和CCL 2依赖性CL反应存在因果关系， 我们将使用集落刺激因子1受体的抑制剂来消耗循环单核细胞。为了阻止- 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， 神经元的胞体和轴突可以分离。使用RNAseq的基因表达将在ax- 在CCR-/-和野生型动物中进行切开术，以确定哪些轴突切开术诱导的基因依赖于mac， 噬菌体积累由于我们已经表明，Wallerian变性在CCR 2-/-小鼠中是正常的， 单核细胞浸润到DRG被阻断，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在DRG中积累。使用这些新方法，我们 将研究轴突附近巨噬细胞积聚之间关系的潜在机制， 分化的细胞体和轴突生长。强调神经节，未探索的神经炎症部位，代表- 从传统的观点，重点是对远端神经的巨噬细胞的影响，发出了一个范式转变。