Spinal astrocytic MeCP2 regulates Kir4.1 for the maintenance of chronic hyperalgesia in neuropathic pain. Spinal astrocytic MeCP2 regulates Kir4.1 for the maintenance of chronic hyperalgesia in neuropathic pain

Previous studies have suggested that astrocyte activation in the spinal dorsal horn may play an important role in the development of chronic neuropathic pain; but the mechanisms involved in astrocyte activation and their modulatory effects remain unknown. The inward rectifying potassium channel protein 4.1 (Kir4.1) is the most important background K+ channel in astrocytes. However, how Kir4.1 is regulated and contributes to behavioral hyperalgesia in chronic pain is unknown. In this study, single-cell RNA sequencing analysis indicated that the expression of Kir4.1 and Methyl-CpG-binding protein 2 (MeCP2) were both decreased in spinal astrocytes after chronic constriction injury (CCI) in a mouse model. Conditional knockout of the Kir4.1 channel in spinal astrocytes led to hyperalgesia; and overexpression of the Kir4.1 channel in spinal cord relieved CCI-induced hyperalgesia. Expression of spinal Kir4.1 after CCI was regulated by MeCP2. Electrophysiological recording in spinal slices showed that knockdown of Kir4.1 significantly regulated the excitability of astrocytes and then functionally changed the firing patterns of neurons in dorsal spinal cord. Therefore, targeting spinal Kir4.1 maybe an underlying treatment for hyperalgesia in chronic neuropathic pain. Overall design: The spinal cords of adult C57BL/6 J mice at 7 and 14 days after chronic constriction injury of sciatic nerve were analyzed by scRNA-seq.

既往研究表明，脊髓背角星形胶质细胞活化可能在慢性神经性疼痛的发生发展中发挥重要作用，但介导星形胶质细胞活化的具体分子机制及其调控效应仍未明确。内向整流钾通道蛋白4.1（inward rectifying potassium channel protein 4.1, Kir4.1）是星形胶质细胞中最重要的背景钾通道。然而，Kir4.1的调控方式及其在慢性疼痛中引发行为性痛觉超敏的具体机制仍不明晰。本研究通过单细胞RNA测序（single-cell RNA sequencing, scRNA-seq）分析发现，小鼠坐骨神经慢性压迫性损伤（chronic constriction injury, CCI）模型中，脊髓星形胶质细胞内Kir4.1与甲基CpG结合蛋白2（Methyl-CpG-binding protein 2, MeCP2）的表达均出现下调。脊髓星形胶质细胞中Kir4.1通道的条件性敲除可诱发痛觉超敏；而在脊髓组织中过表达Kir4.1通道则可缓解CCI诱导的痛觉超敏。CCI造模后脊髓Kir4.1的表达受MeCP2调控。脊髓切片的电生理记录结果显示，敲低Kir4.1可显著改变星形胶质细胞的兴奋性，进而功能性调控脊髓背角神经元的放电模式。因此，靶向脊髓Kir4.1或可成为治疗慢性神经性疼痛相关痛觉超敏的潜在干预手段。整体实验设计：本研究对成年C57BL/6J小鼠坐骨神经慢性压迫性损伤后第7天和第14天的脊髓组织进行了scRNA-seq分析。