CXCL13 通过 CXCR5 介导的 NF-κB 激活和脊髓背角促炎细胞因子的产生，促进 CRPS-I 小鼠模型的慢性疼痛。

CXCL13 contributes to chronic pain of a mouse model of CRPS-I via CXCR5-mediated NF-κB activation and pro-inflammatory cytokine production in spinal cord dorsal horn.

机构信息

Department of Neurobiology and Acupuncture Research, Key Laboratory of Acupuncture and Neurology of Zhejiang Province, The Third Clinical Medical College, Zhejiang Chinese Medical University, Hangzhou, 310053, China.

Department of Rehabilitation in Traditional Chinese Medicine, The Second Affiliated Hospital of Zhejiang University School of Medicine, Hangzhou, China.

出版信息

J Neuroinflammation. 2023 May 8;20(1):109. doi: 10.1186/s12974-023-02778-x.

BACKGROUND

Complex regional pain syndrome type-I (CRPS-I) causes excruciating pain that affect patients' life quality. However, the mechanisms underlying CRPS-I are incompletely understood, which hampers the development of target specific therapeutics.

METHODS

The mouse chronic post-ischemic pain (CPIP) model was established to mimic CRPS-I. qPCR, Western blot, immunostaining, behavioral assay and pharmacological methods were used to study mechanisms underlying neuroinflammation and chronic pain in spinal cord dorsal horn (SCDH) of CPIP mice.

RESULTS

CPIP mice developed robust and long-lasting mechanical allodynia in bilateral hindpaws. The expression of inflammatory chemokine CXCL13 and its receptor CXCR5 was significantly upregulated in ipsilateral SCDH of CPIP mice. Immunostaining revealed CXCL13 and CXCR5 was predominantly expressed in spinal neurons. Neutralization of spinal CXCL13 or genetic deletion of Cxcr5 (Cxcr5) significantly reduced mechanical allodynia, as well as spinal glial cell overactivation and c-Fos activation in SCDH of CPIP mice. Mechanical pain causes affective disorder in CPIP mice, which was attenuated in Cxcr5 mice. Phosphorylated STAT3 co-expressed with CXCL13 in SCDH neurons and contributed to CXCL13 upregulation and mechanical allodynia in CPIP mice. CXCR5 coupled with NF-κB signaling in SCDH neurons to trigger pro-inflammatory cytokine gene Il6 upregulation, contributing to mechanical allodynia. Intrathecal CXCL13 injection produced mechanical allodynia via CXCR5-dependent NF-κB activation. Specific overexpression of CXCL13 in SCDH neurons is sufficient to induce persistent mechanical allodynia in naïve mice.

CONCLUSIONS

These results demonstrated a previously unidentified role of CXCL13/CXCR5 signaling in mediating spinal neuroinflammation and mechanical pain in an animal model of CRPS-I. Our work suggests that targeting CXCL13/CXCR5 pathway may lead to novel therapeutic approaches for CRPS-I.

背景

复杂性区域疼痛综合征 I 型（CRPS-I）会引起剧痛，从而影响患者的生活质量。然而，CRPS-I 的发病机制尚未完全阐明，这阻碍了针对特定靶点的治疗方法的开发。

方法

建立了慢性缺血后痛（CPIP）模型来模拟 CRPS-I。采用 qPCR、Western blot、免疫染色、行为学检测和药理学方法，研究 CPIP 小鼠脊髓背角（SCDH）中神经炎症和慢性痛的发病机制。

结果

CPIP 小鼠双侧后爪出现了强烈且持久的机械性痛觉过敏。CPIP 小鼠同侧 SCDH 中炎症趋化因子 CXCL13 及其受体 CXCR5 的表达显著上调。免疫染色显示 CXCL13 和 CXCR5 主要表达于脊髓神经元。脊髓 CXCL13 的中和或 Cxcr5 基因敲除（Cxcr5）显著减轻了 CPIP 小鼠的机械性痛觉过敏，以及 SCDH 中脊髓胶质细胞的过度激活和 c-Fos 的激活。CPIP 小鼠的机械性疼痛导致了情感障碍，而 Cxcr5 小鼠的这种障碍则有所减轻。磷酸化 STAT3 与 SCDH 神经元中的 CXCL13 共表达，促进了 CPIP 小鼠中 CXCL13 的上调和机械性痛觉过敏。CXCR5 在 SCDH 神经元中与 NF-κB 信号偶联，触发促炎细胞因子基因 Il6 的上调，导致机械性痛觉过敏。鞘内注射 CXCL13 通过 CXCR5 依赖的 NF-κB 激活引起机械性痛觉过敏。SCDH 神经元中 CXCL13 的特异性过表达足以在正常小鼠中引起持续的机械性痛觉过敏。