Pain Research Laboratory, Institute of Nautical Medicine, Jiangsu Key Laboratory of Neuroregeneration, Nantong University, 19 Qixiu Road, Nantong 226001, China.
J Neuroinflammation. 2014 Mar 1;11:38. doi: 10.1186/1742-2094-11-38.
Bone cancer pain (BCP) is one of the most disabling factors in patients suffering from primary bone cancer or bone metastases. Recent studies show several chemokines (for example, CCL2, CXCL10) in the spinal cord are involved in the pathogenesis of BCP. Here we investigated whether and how spinal CXCL1 contributes to BCP.
Mouse prostate tumor cell line, RM-1 cells were intramedullary injected into the femur to induce BCP. The mRNA expression of CXCL1 and CXCR2 was detected by quantitative real-time PCR. The protein expression and distribution of CXCL1, NFκB, and CXCR2 was examined by immunofluorescence staining and western blot. The effect of CXCL1 neutralizing antibody, NFκB antagonist, and CXCR2 antagonist on pain hypersensitivity was checked by behavioral testing.
Intramedullary injection of RM-1 cells into the femur induced cortical bone damage and persistent (>21 days) mechanical allodynia and heat hyperalgesia. Tumor cell inoculation also produced CXCL1 upregulation in activated astrocytes in the spinal cord for more than 21 days. Inhibition of CXCL1 by intrathecal administration of CXCL1 neutralizing antibody at 7 days after inoculation attenuated mechanical allodynia and heat hyperalgesia. In cultured astrocytes, TNF-α induced robust CXCL1 expression, which was dose-dependently decreased by NFκB inhibitor. Furthermore, inoculation induced persistent NFκB phosphorylation in spinal astrocytes. Intrathecal injection of NFκB inhibitor attenuated BCP and reduced CXCL1 increase in the spinal cord. Finally, CXCR2, the primary receptor of CXCL1, was upregulated in dorsal horn neurons after inoculation. Inhibition of CXCR2 by its selective antagonist SB225002 attenuated BCP.
NFκB mediates CXCL1 upregulation in spinal astrocytes in the BCP model. In addition, CXCL1 may be released from astrocytes and act on CXCR2 on neurons in the spinal cord and be involved in the maintenance of BCP. Inhibition of the CXCL1 signaling may provide a new therapy for BCP management.
骨癌痛（BCP）是原发性骨癌或骨转移患者中最致残的因素之一。最近的研究表明，脊髓中的几种趋化因子（例如 CCL2、CXCL10）参与了 BCP 的发病机制。在这里，我们研究了脊髓 CXCL1 是否以及如何参与 BCP。
将小鼠前列腺癌细胞系 RM-1 细胞注射到股骨中，以诱导 BCP。通过定量实时 PCR 检测 CXCL1 和 CXCR2 的 mRNA 表达。通过免疫荧光染色和 Western blot 检测 CXCL1、NFκB 和 CXCR2 的蛋白表达和分布。通过行为测试检查 CXCL1 中和抗体、NFκB 拮抗剂和 CXCR2 拮抗剂对痛觉过敏的影响。
将 RM-1 细胞注射到股骨中会导致皮质骨损伤和持续（>21 天）机械性痛觉过敏和热痛觉过敏。肿瘤细胞接种还导致脊髓中激活的星形胶质细胞中超过 21 天的 CXCL1 上调。在接种后 7 天鞘内给予 CXCL1 中和抗体抑制 CXCL1 可减轻机械性痛觉过敏和热痛觉过敏。在培养的星形胶质细胞中，TNF-α诱导强烈的 CXCL1 表达，NFκB 抑制剂剂量依赖性地降低。此外，接种诱导脊髓星形胶质细胞中持续的 NFκB 磷酸化。鞘内注射 NFκB 抑制剂可减轻 BCP 并减少脊髓中 CXCL1 的增加。最后，接种后背角神经元中 CXCR2（CXCL1 的主要受体）上调。其选择性拮抗剂 SB225002 抑制 CXCR2 可减轻 BCP。
NFκB 介导 BCP 模型中脊髓星形胶质细胞中 CXCL1 的上调。此外，CXCL1 可能从星形胶质细胞释放，并作用于脊髓神经元上的 CXCR2，并参与 BCP 的维持。抑制 CXCL1 信号可能为 BCP 管理提供新的治疗方法。
