Freria Camila M, Hall Jodie C E, Wei Ping, Guan Zhen, McTigue Dana M, Popovich Phillip G
Department of Neuroscience and Center for Brain and Spinal Cord Repair, Ohio State University, Wexner Medical Center, Columbus, Ohio 43210.
Department of Neuroscience and Center for Brain and Spinal Cord Repair, Ohio State University, Wexner Medical Center, Columbus, Ohio 43210
J Neurosci. 2017 Mar 29;37(13):3568-3587. doi: 10.1523/JNEUROSCI.2841-16.2017. Epub 2017 Mar 6.
Impaired signaling via CX3CR1, the fractalkine receptor, promotes recovery after traumatic spinal contusion injury in mice, a benefit achieved in part by reducing macrophage-mediated injury at the lesion epicenter. Here, we tested the hypothesis that CX3CR1-dependent changes in microglia and macrophage functions also will enhance neuroplasticity, at and several segments below the injury epicenter. New data show that in the presence of inflammatory stimuli, CX3CR1-deficient (CX3CR1) microglia and macrophages adopt a reparative phenotype and increase expression of genes that encode neurotrophic and gliogenic proteins. At the lesion epicenter (mid-thoracic spinal cord), the microenvironment created by CX3CR1 microglia/macrophages enhances NG2 cell responses, axon sparing, and sprouting of serotonergic axons. In lumbar spinal cord, inflammatory signaling is reduced in CX3CR1 microglia. This is associated with reduced dendritic pathology and improved axonal and synaptic plasticity on ventral horn motor neurons. Together, these data indicate that CX3CR1, a microglia-specific chemokine receptor, is a novel therapeutic target for enhancing neuroplasticity and recovery after SCI. Interventions that specifically target CX3CR1 could reduce the adverse effects of inflammation and augment activity-dependent plasticity and restoration of function. Indeed, limiting CX3CR1-dependent signaling could improve rehabilitation and spinal learning. Published data show that genetic deletion of CX3CR1, a microglia-specific chemokine receptor, promotes recovery after traumatic spinal cord injury in mice, a benefit achieved in part by reducing macrophage-mediated injury at the lesion epicenter. Data in the current manuscript indicate that CX3CR1 deletion changes microglia and macrophage function, creating a tissue microenvironment that enhances endogenous repair and indices of neuroplasticity, at and several segments below the injury epicenter. Interventions that specifically target CX3CR1 might be used in the future to reduce the adverse effects of intraspinal inflammation and augment activity-dependent plasticity (e.g., rehabilitation) and restoration of function.
通过CX3CR1( fractalkine受体)的信号传导受损可促进小鼠创伤性脊髓挫伤损伤后的恢复,这一益处部分是通过减少损伤中心巨噬细胞介导的损伤实现的。在此,我们测试了以下假设:小胶质细胞和巨噬细胞功能中依赖CX3CR1的变化也将增强损伤中心及其下方几个节段的神经可塑性。新数据表明,在存在炎症刺激的情况下,CX3CR1缺陷型(CX3CR1-/-)小胶质细胞和巨噬细胞呈现修复表型,并增加编码神经营养和胶质生成蛋白的基因表达。在损伤中心(胸段脊髓中部),由CX3CR1-/-小胶质细胞/巨噬细胞创造的微环境增强了NG2细胞反应、轴突保留以及血清素能轴突的发芽。在腰段脊髓中,CX3CR1-/-小胶质细胞中的炎症信号减少。这与树突病理减少以及腹角运动神经元的轴突和突触可塑性改善有关。总之,这些数据表明,CX3CR1是一种小胶质细胞特异性趋化因子受体,是增强脊髓损伤后神经可塑性和恢复的新型治疗靶点。特异性靶向CX3CR1的干预措施可以减少炎症的不利影响,并增强活动依赖性可塑性和功能恢复。事实上,限制依赖CX3CR1的信号传导可以改善康复和脊髓学习。已发表的数据表明,小胶质细胞特异性趋化因子受体CX3CR1的基因缺失可促进小鼠创伤性脊髓损伤后的恢复,这一益处部分是通过减少损伤中心巨噬细胞介导的损伤实现的。本手稿中的数据表明,CX3CR1缺失改变了小胶质细胞和巨噬细胞功能,在损伤中心及其下方几个节段创造了一个增强内源性修复和神经可塑性指标的组织微环境。未来可能会使用特异性靶向CX3CR1的干预措施来减少脊髓内炎症的不利影响,并增强活动依赖性可塑性(如康复)和功能恢复。
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