炎性疼痛是由周围组织炎症引起的慢性疼痛，严重影响患者的生活质量。华蟾素注射液作为一种中药注射制剂，在晚期肿瘤患者的抗炎镇痛治疗中表现出优异的疗效。本研究报道了华蟾素注射液中天然存在的一种具有抗炎镇痛生物功能的新型镇痛肽CI5及其调节机制。我们的结果表明，给予CI5可显着缓解醋酸捻转镇痛模型和福尔马林炎性疼痛模型中小鼠的疼痛。此外，CI5还能有效降低炎症细胞因子（IL-6、TNF-α和IL-1β）和炎症介质（PGE2）的表达，并预防角叉菜胶引起的小鼠足爪水肿。进一步的LC-MS/MS结果显示CI5的抗炎和镇痛生物功能取决于其与ERK1/2上游的Rac-2蛋白和炎症信号通路（ERK1/2/COX-2轴）的相互作用。总之，CI5 作为从华蟾素注射液中鉴定出的新型天然候选药物，在治疗炎症性疼痛方面显示出巨大的临床前景。版权所有 © 2024 Elsevier B.V. 保留所有权利。

Inflammatory pain is a chronic pain caused by peripheral tissue inflammation, seriously impacting the patient's life quality. Cinobufacini injection, as a traditional Chinese medicine injection preparation, shows excellent efficacy in anti-inflammatory and analgesic treatment in patients with advanced tumors. In this study, a novel analgesic peptide CI5 with anti-inflammatory and analgesic bio-functions that naturally presents in Cinobufacini injection and its regulatory mechanism are reported. Our results showed that the administration of CI5 significantly relieved the pain of mice in the acetic acid twisting analgesic model and formalin inflammatory pain model. Furthermore, CI5 effectively reduced the inflammatory cytokines (IL-6, TNF-α and IL-1β) and inflammatory mediator (PGE2) expressions, and prevented the carrageenan-induced paw edema in mice. Further LC-MS/MS results showed the anti-inflammatory and analgesic bio-functions of CI5 depended on its interaction with the Rac-2 protein upstream of ERK1/2 and the inflammatory signaling pathway (ERK1/2/COX-2 axis). In summary, CI5, as a novel natural candidate identified from Cinobufacini injection, showed substantial clinical promise for inflammatory pain treatments.Copyright © 2024 Elsevier B.V. All rights reserved.