Neuroinflammation Grading and Adjusting of Spinal Sensorimotor Circuitries in Response to Remote Injuries in Peripheral Nerves

神经炎症分级和脊髓感觉运动回路响应周围神经远程损伤的调整

• 批准号: 10341146
• 负责人: FRANCISCO J ALVAREZ
• 金额: $ 36.24万
• 依托单位: EMORY UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2020
• 资助国家: 美国
• 起止时间: 2020-04-01 至 2024-01-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/10341146
• 关键词: Affect; Alleles; Animal Model; Axon; Blood; Brachial plexus structure; Brain; CCL2 gene; Cells; Complement; Data; Disease; Excision; Face; Feedback; Functional disorder; Future; Goals; Horns; Immune; Immune system; Impairment; Infiltration; Inflammatory; Injury; Joints; Knowledge; Label; Length; Lesion; Life; Ligands; Light; Locomotion; Mediating; Methods; Microglia; Motor; Motor output; Movement; Mus; Muscle; Natural regeneration; Nerve; Nerve Crush; Nerve Regeneration; Neuraxis; Neuronal Plasticity; Operative Surgical Procedures; Outcome; Parents; Patients; Pattern; Peripheral; Peripheral Nerves; Phagocytes; Phagocytosis; Physiological; Process; Reaction; Recovery; Recovery of Function; Role; Sensorimotor functions; Sensory; Severities; Signal Transduction; Site; Specific qualifier value; Specificity; Speed; Spinal; Spinal Cord; Stretching; Synapses; Synaptic plasticity; Techniques; Testing; Time; Up-Regulation; Ventral Horn of the Spinal Cord; Work; antagonist; awake; axon injury; axon regeneration; cell type; chemokine; chemokine receptor; design; diphtheria toxin receptor; dorsal column; dorsal horn; genetic approach; improved; injured; macrophage; monocyte; motor control; motor deficit; motor disorder; motor function improvement; muscle reinnervation; nerve injury; nerve supply; nerve transection; neural circuit; neuroinflammation; novel strategies; patient prognosis; peripheral nerve regeneration; preservation; prevent; recruit; reinnervation; response; sciatic nerve injury; stretch reflex; time use; treadmill; two photon microscopy; Affect; Alleles; Animal Model; Axon; Blood; Brachial plexus structure; Brain; CCL2 gene; Cells; Complement; Data; Disease; Excision; Face; Feedback; Functional disorder; Future; Goals; Horns; Immune; Immune system; Impairment; Infiltration; Inflammatory; Injury; Joints; Knowledge; Label; Length; Lesion; Life; Ligands; Light; Locomotion; Mediating; Methods; Microglia; Motor; Motor output; Movement; Mus; Muscle; Natural regeneration; Nerve; Nerve Crush; Nerve Regeneration; Neuraxis; Neuronal Plasticity; Operative Surgical Procedures; Outcome; Parents; Patients; Pattern; Peripheral; Peripheral Nerves; Phagocytes; Phagocytosis; Physiological; Process; Reaction; Recovery; Recovery of Function; Role; Sensorimotor functions; Sensory; Severities; Signal Transduction; Site; Specific qualifier value; Specificity; Speed; Spinal; Spinal Cord; Stretching; Synapses; Synaptic plasticity; Techniques; Testing; Time; Up-Regulation; Ventral Horn of the Spinal Cord; Work; antagonist; awake; axon injury; axon regeneration; cell type; chemokine; chemokine receptor; design; diphtheria toxin receptor; dorsal column; dorsal horn; genetic approach; improved; injured; macrophage; monocyte; motor control; motor deficit; motor disorder; motor function improvement; muscle reinnervation; nerve injury; nerve supply; nerve transection; neural circuit; neuroinflammation; novel strategies; patient prognosis; peripheral nerve regeneration; preservation; prevent; recruit; reinnervation; response; sciatic nerve injury; stretch reflex; time use; treadmill; two photon microscopy

Project Summary / Abstract Nerve injury patients face life-long sensorimotor deficits despite continued improvements in microsurgical techniques and nerve regeneration. These are usually believed to result from poor or unspecific regeneration of the peripheral nerve. However, deficits are still present when experimental nerve injuries are designed in animal models for rapid, specific and efficient nerve regeneration and muscle re-innervation. We have proposed that structural remodeling of spinal cord circuitry after nerve lesions is in part responsible. Thus, future advances in nerve regeneration will predictably be limited by deficits caused by this much less studied central synaptic plasticity. Remarkably, the central synaptic branches of Ia afferent proprioceptive axons injured in the periphery are removed from the spinal cord ventral horn after nerve injury resulting in dysfunction of critical motor control circuits. We recently found that this synaptic plasticity is graded to the type of nerve injury and correlated with the more or less target specificity obtained during muscle reinnervation. Our preliminary data suggest that neuroinflammation occurring inside the otherwise intact spinal cord ventral horn, is critical for grading circuit remodeling to the severity of the nerve injury. Ventral horn microglia are activated after nerve injuries and although their capacity for synapse phagocytosis has been frequently proposed, their function inside the spinal cord after a remote nerve injury continues to be debated. Moreover, we found that microglia activation is followed by infiltration of cells from the adaptive and innate peripheral immune system, but this is variable depending on injury type. When occurs, it correlates with maximal Ia synapse and axon removal from the ventral horn. These cells, particularly monocyte/macrophages were missed in previous studies because they share many markers with activated microglia, preventing their identification. Thus, their function inside the spinal cord ventral horn after nerve injury is unexplored. We will use genetic approaches to distinguish microglia from blood-derived immune cells and investigate their significance for Ia afferent removal. In Aim 1 we will genetically label and manipulate each cell type to test their roles in Ia axon and synapse deletions and probe cellular signaling mechanisms. In Aim 2 we will visualize with time-lapse two-photon microscopy genetically labeled sensory afferents and microglia or monocyte-derived cells to directly observe and analyze their interactions. Finally, in Aim 3 we will test the relevance of this mechanism for motor function, whether is maladaptive, causing long-lasting motor deficits or adaptive, to preserve the best function possible when peripheral connectivity becomes highly scrambled after regeneration. The new knowledge generated will allow us to consider new methods for optimization of central circuitry function through modulation of central neuroinflammation. This will be critical for developing strategies to improve sensorimotor function recovery in conjunction with methods to improve the speed, efficiency and specify of axon regeneration in the periphery.

项目摘要 /摘要 神经损伤患者尽管持续改善了微神经损伤的终生感觉运动缺陷 技术和神经再生。这些通常被认为是由于较差或未特异性的再生而产生的 外周神经。但是，在设计实验神经损伤时仍然存在缺陷 动物模型，用于快速，特异性和有效的神经再生和肌肉再现。我们有 提出，神经病变后脊髓回路的结构重塑部分是造成的。因此， 可以预见的 中央突触可塑性。值得注意的是，IA传入本体感受轴突的中央突触分支 神经损伤后从脊髓腹角移除外围受伤，导致功能障碍 关键运动控制电路。我们最近发现，这种突触可塑性被分级为神经的类型 损伤，与在肌肉加剧期间获得的目标特异性或多或少相关。我们的 初步数据表明，神经炎症发生在原本完整的脊髓腹角内， 对于对神经损伤的严重程度进行评分的电路重塑至关重要。腹角小胶质细胞激活 神经损伤并经常提出其突触吞噬作用的能力，但 远程神经损伤后，脊髓内部的功能继续进行辩论。而且，我们发现 小胶质细胞激活之后是从适应性和先天外周免疫系统中浸润细胞的 但这是可变的，具体取决于伤害类型。当发生时，它与最大IA突触和轴突相关 从腹角移除。这些细胞，尤其是单核细胞/巨噬细胞在以前的 研究是因为它们共享许多具有活化的小胶质细胞的标记，从而阻止了它们的识别。因此，他们 神经损伤后脊髓腹角内部的功能未探索。我们将使用遗传方法 将小胶质细胞与血液衍生的免疫细胞区分开，并研究其对IA传入去除的重要性。 在AIM 1中，我们将基因标记并操纵每种细胞类型，以测试其在IA轴突和突触中的作用 缺失和探针细胞信号传导机制。在AIM 2中，我们将通过延时的两光量进行可视化 显微镜遗传标记的感觉传入和小胶质细胞或单核细胞衍生细胞直接观察 并分析他们的互动。最后，在AIM 3中，我们将测试该机制与运动功能的相关性， 无论是适应不良，导致持久的运动缺陷还是适应性，以保持最佳功能 当再生后周围连接变得高度争夺时。产生的新知识将 允许我们考虑通过调制中央来优化中央电路功能的新方法 神经炎症。这对于制定改善感觉运动功能恢复的策略至关重要 与提高外围轴突再生的速度，效率和指定的方法的结合。