From the Department of Integrative Medicine and Neurobiology, School of Basic Medical Sciences, Shanghai Medical College, Institute of Acupuncture Research, Institutes of Integrative Medicine.
State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Institutes of Brain Science.
Anesth Analg. 2022 Jan 1;134(1):204-215. doi: 10.1213/ANE.0000000000005768.
The main symptoms of chemotherapy-induced peripheral neuropathy (CIPN) include pain and numbness. Neuronal G protein-coupled receptor kinase 2 (GRK2) plays an important role in various pain models. Cisplatin treatment can induce the activation of proinflammatory microglia in spinal cord. The purpose of this study was to investigate the role of spinal neuronal GRK2 in cisplatin-induced CIPN and in the prevention of CIPN by electroacupuncture (EA).
The pain and sensory deficit behaviors of mice were examined by von Frey test and adhesive removal test. The expression of neuronal GRK2 in the spinal cord is regulated by intraspinal injection of adeno-associated virus (AAV) containing neuron-specific promoters. The protein levels of GRK2, triggering receptor expressed on myeloid cells 2 (TREM2), and DNAX-activating protein of 12 kDa (DAP12) in spinal dorsal horn were detected by Western blot, the density of intraepidermal nerve fibers (IENFs) was detected by immunofluorescence, and microglia activation were evaluated by real-time polymerase chain reaction (PCR).
In this study, cisplatin treatment led to the decrease of GRK2 expression in the dorsal horn of spinal cord. Overexpression of neuronal GRK2 in spinal cord by intraspinal injection of an AAV vector expressing GRK2 with human synapsin (hSyn) promotor significantly inhibited the loss of IENFs and alleviated the mechanical pain and sensory deficits induced by cisplatin. Real-time PCR analysis showed that the overexpression of neuronal GRK2 significantly inhibited the messenger RNA (mRNA) upregulation of proinflammatory cytokine interleukin (IL)-1β, IL-6, inducible nitric oxide synthase (iNOS), and M1 microglia marker cluster of differentiation (CD)16 induced by cisplatin. Furthermore, the TREM2 and DAP12, which has been demonstrated to play a role in microglia activation and in the development of CIPN, were also downregulated by overexpression of neuronal GRK2 in this study. Interestingly, preventive treatment with EA completely mimics the effect of overexpression of neuronal GRK2 in the spinal cord in this mouse model of cisplatin-induced CIPN. EA increased GRK2 level in spinal dorsal horn after cisplatin treatment. Intraspinal injection of AAV vector specifically downregulated neuronal GRK2, completely reversed the regulatory effect of EA on CIPN and microglia activation. All these indicated that the neuronal GRK2 mediated microglial activation contributed to the process of CIPN.
Neuronal GRK2 in the spinal cord contributed to the preventive effect of EA on CIPN. The neuronal GRK2 may be a potential target for CIPN intervention.
化疗引起的周围神经病（CIPN）的主要症状包括疼痛和麻木。神经元 G 蛋白偶联受体激酶 2（GRK2）在各种疼痛模型中发挥重要作用。顺铂治疗可诱导脊髓中促炎小胶质细胞的激活。本研究旨在探讨脊髓神经元 GRK2 在顺铂诱导的 CIPN 中的作用以及电针（EA）预防 CIPN 的作用。
通过 von Frey 试验和粘贴去除试验检测小鼠的疼痛和感觉缺陷行为。通过脊髓内注射含有神经元特异性启动子的腺相关病毒（AAV）调节脊髓中神经元 GRK2 的表达。Western blot 检测脊髓背角中 GRK2、髓样细胞触发受体 2（TREM2）和 12kDa 的 DNAX 激活蛋白（DAP12）的蛋白水平，免疫荧光检测表皮内神经纤维（IENFs）的密度，实时聚合酶链反应（PCR）评估小胶质细胞激活。
本研究中，顺铂处理导致脊髓背角中 GRK2 表达减少。通过脊髓内注射表达人类突触蛋白（hSyn）启动子的 GRK2 的 AAV 载体，使 GRK2 在脊髓中过表达，显著抑制 IENFs 的丢失，并减轻顺铂引起的机械性疼痛和感觉缺陷。实时 PCR 分析表明，神经元 GRK2 的过表达显著抑制了顺铂诱导的促炎细胞因子白细胞介素（IL）-1β、IL-6、诱导型一氧化氮合酶（iNOS）和 M1 小胶质细胞标记物 CD16 的 mRNA 上调。此外，本研究还表明，TREM2 和 DAP12 在小胶质细胞激活和 CIPN 发展中起作用，也被过表达神经元 GRK2 下调。有趣的是，预防性 EA 治疗在这种顺铂诱导的 CIPN 小鼠模型中完全模拟了脊髓中神经元 GRK2 过表达的作用。EA 增加了顺铂治疗后脊髓背角中的 GRK2 水平。脊髓内注射 AAV 载体特异性下调神经元 GRK2，完全逆转了 EA 对 CIPN 和小胶质细胞激活的调节作用。所有这些都表明，脊髓中的神经元 GRK2 介导的小胶质细胞激活参与了 CIPN 的发生过程。
脊髓中的神经元 GRK2 有助于 EA 对 CIPN 的预防作用。神经元 GRK2 可能是 CIPN 干预的潜在靶点。
