Guo Jinding, Gao Kaiming, Chen Xi, Liao Chengppeng, Rui Jing, Zhou Yingjie, Lao Jie
Department of Hand Surgery, Huashan Hospital, Fudan University, Shanghai, China.
Shanghai Key Laboratory of Peripheral Nerve and Microsurgery, Shanghai, China.
Reg Anesth Pain Med. 2024 Nov 12. doi: 10.1136/rapm-2024-105801.
Many patients with brachial plexus avulsion (BPA) suffer from neuropathic pain, but the mechanism remains elusive. Modifications of histones, the proteins responsible for organizing DNA, may play an important role in neuropathic pain. Lysine demethylase 4A (KDM4A), an essential component of histone demethylase, can modify the function of chromatin and thus regulate the vital gene expressions. However, the mechanism by which KDM4A regulates neuropathic pain following BPA remains unclear.
The pain model was developed in adult rats that received BPA surgery. Western blot, ELISA, and reverse transcription-PCR were used to examine the protein and mRNA levels of targeted genes. Immunofluorescence studies were conducted to analyze their cellular distribution in the spinal cord. Pharmacological and genetic methods were used to modulate the expression of KDM4A. Co-immunoprecipitation and chromatin immunoprecipitation PCR were used to assess the binding potential between KDM4A and the promoter of brain-derived neurotrophic factor (BDNF).
KDM4A and BDNF levels were significantly upregulated in the ipsilateral spinal cord dorsal horn in the BPA group compared with the sham surgery group. Additionally, knockdown of KDM4A decreased BDNF expression and microgliosis and reduced neuropathic pain-like behaviors in BPA rats. Conversely, KDM4A overexpression increased BDNF expression and microgliosis and exacerbated neuropathic pain. BDNF inhibitors and activators also regulated the activation of spinal microglia and neuropathic pain. Importantly, we showed that KDM4A modulates BDNF expression by regulating the methylation of histone 3 lysine 9 and histone 3 lysine 36 in its promoter region.
Current findings suggest that the upregulation of KDM4A increases BDNF expression in the spinal cord in rats after BPA, contributing to microgliosis, neuroinflammation, and neuropathic pain.
许多臂丛神经撕脱伤（BPA）患者患有神经性疼痛，但其机制仍不清楚。组蛋白是负责组织DNA的蛋白质，其修饰可能在神经性疼痛中起重要作用。赖氨酸去甲基化酶4A（KDM4A）是组蛋白去甲基化酶的重要组成部分，可改变染色质功能，从而调节重要基因的表达。然而，KDM4A在BPA后调节神经性疼痛的机制仍不清楚。
在接受BPA手术的成年大鼠中建立疼痛模型。采用蛋白质免疫印迹法、酶联免疫吸附测定法和逆转录聚合酶链反应检测靶基因的蛋白质和mRNA水平。进行免疫荧光研究以分析它们在脊髓中的细胞分布。采用药理学和遗传学方法调节KDM4A的表达。采用免疫共沉淀和染色质免疫沉淀聚合酶链反应评估KDM4A与脑源性神经营养因子（BDNF）启动子之间的结合潜力。
与假手术组相比，BPA组同侧脊髓背角KDM4A和BDNF水平显著上调。此外，敲低KDM4A可降低BPA大鼠的BDNF表达和小胶质细胞增生，并减轻神经性疼痛样行为。相反，KDM4A过表达增加BDNF表达和小胶质细胞增生，并加重神经性疼痛。BDNF抑制剂和激活剂也调节脊髓小胶质细胞的激活和神经性疼痛。重要的是，我们发现KDM4A通过调节其启动子区域组蛋白3赖氨酸9和组蛋白3赖氨酸36的甲基化来调节BDNF表达。
目前的研究结果表明，KDM4A的上调增加了BPA后大鼠脊髓中BDNF的表达，导致小胶质细胞增生、神经炎症和神经性疼痛。
