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

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.

项目概要/摘要 尽管显微外科技术不断进步，但神经损伤患者仍面临终生的感觉运动缺陷 技术和神经再生。这些通常被认为是由于再生不良或非特异性造成的 的周围神经。然而，当设计实验性神经损伤时，缺陷仍然存在 快速、特异和高效的神经再生和肌肉神经支配的动物模型。我们有 提出神经损伤后脊髓回路的结构重塑是部分原因。因此， 可以预见的是，神经再生的未来进展将受到这种研究较少所造成的缺陷的限制 中枢突触可塑性。值得注意的是，Ia 传入本体感觉轴突的中央突触分支 外周受伤者在神经损伤导致功能障碍后从脊髓腹角切除 关键电机控制电路。我们最近发现这种突触可塑性根据神经类型而分级 损伤并与肌肉神经支配过程中获得的或多或少的目标特异性相关。我们的 初步数据表明，神经炎症发生在原本完好的脊髓腹角内， 对于根据神经损伤的严重程度进行电路重塑的分级至关重要。腹角小胶质细胞被激活 神经损伤后，虽然人们经常提出它们的突触吞噬能力，​​但它们 远程神经损伤后脊髓内部的功能仍然存在争议。此外，我们发现 小胶质细胞激活后，适应性和先天性外周免疫系统的细胞浸润， 但这取决于伤害类型。当发生时，它与最大 Ia 突触和轴突相关 从腹角去除。这些细胞，特别是单核细胞/巨噬细胞在之前的研究中被遗漏了。 研究，因为它们与激活的小胶质细胞共享许多标记，从而阻止了它们的识别。因此，他们的 神经损伤后脊髓腹角内部的功能尚未被探索。我们将使用遗传方法 区分小胶质细胞和血液来源的免疫细胞，并研究它们对 Ia 传入去除的意义。 在目标 1 中，我们将对每种细胞类型进行基因标记和操作，以测试它们在 Ia 轴突和突触中的作用 缺失并探测细胞信号传导机制。在目标 2 中，我们将使用延时双光子进行可视化 显微镜基因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 并分析它们的相互作用。最后，在目标 3 中，我们将测试该机制与运动功能的相关性， 是否是适应不良，导致长期运动缺陷，还是适应性，以保持最佳功能 当外围连接在再生后变得高度混乱时。产生的新知识将 允许我们考虑通过调节中央电路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 结合提高外周轴突再生速度、效率和规格的方法。