Chunyan Wang1, Qing Li1, Zhen Jia1, Haifang Zhang1, Yize Li1, Qi Zhao1, Lin Su1, Yang Yu2, Rubin Xu3. 1. Department of Anesthesiology, Tianjin Medical University General Hospital, Tianjin Research Institute of Anesthesiology, Tianjin, 300052, China. 2. Department of Anesthesiology, Tianjin Medical University General Hospital, Tianjin Research Institute of Anesthesiology, Tianjin, 300052, China. Electronic address: sevenyu1987@qq.com. 3. Department of Anesthesiology, Tianjin First Center Hospital, Tianjin, 300192, China. Electronic address: xurubin2019da@163.com.
Abstract
BACKGROUND: Neuroinflammation in the spinal cord is a pathological event in remifentanil-induced hyperalgesia (RIH), but its underlying molecular mechanisms remain unclear. Recent studies recapitulate the significance of the intracellular protease caspase-6 in the release of inflammatory mediators and synaptic plasticity in pathologic pain. Also, chemokine CCL21 is involved in microglia activation and nociceptive transduction. This study examined whether spinal caspase-6 is associated with RIH via CCL21 and its receptor CXCR3. METHODS: The acute exposure to remifentanil (1 μg kg-1 min-1for 60 min) was used to establish RIH, verified by assessment of mechanical paw withdrawal threshold and thermal paw withdrawal latency. The caspase-6 inhibitor, a neutralizing antibody against CCL21 (anti-CCL21), a selective CXCR3 antagonist NBI-74330, recombinant caspase-6 and CCL21 were used for the investigation of pathogenesis as well as the prevention of hyperalgesia. The expression of caspase-6, CCL21 and CXCR3 was also evaluated by RT-qPCR and Western blot. RESULTS: This study discovered mechanical allodynia and thermal hyperalgesia along with the increase in the expression of spinal caspase-6 and CCL21/CXCR3 after remifentanil exposure. Central caspase-6 inhibition prevented behavioral RIH and spinal up-regulation of CCL21/CXCR3 level. Intrathecal anti-CCL21 injection reduced RIH and spinal expression of CXCR3. The delivery of recombinant caspase-6 facilitated acute nociceptive hypersensitivity and increased spinal CXCR3 release in naïve rats, reversing by co-application of anti-CCL21. Also, NBI-74330 attenuated RIH and exogenous CCL21-caused acute pain behaviors. CONCLUSION: This study highlighted that spinal caspase-6-mediated up-regulation of CCL21/CXCR3 is vital in the pathogenesis of RIH in rats.
BACKGROUND: Neuroinflammation in the spinal cord is a pathological event in remifentanil-induced hyperalgesia (RIH), but its underlying molecular mechanisms remain unclear. Recent studies recapitulate the significance of the intracellular protease caspase-6 in the release of inflammatory mediators and synaptic plasticity in pathologic pain. Also, chemokine CCL21 is involved in microglia activation and nociceptive transduction. This study examined whether spinal caspase-6 is associated with RIH via CCL21 and its receptor CXCR3. METHODS: The acute exposure to remifentanil (1 μg kg-1 min-1for 60 min) was used to establish RIH, verified by assessment of mechanical paw withdrawal threshold and thermal paw withdrawal latency. The caspase-6 inhibitor, a neutralizing antibody against CCL21 (anti-CCL21), a selective CXCR3 antagonist NBI-74330, recombinant caspase-6 and CCL21 were used for the investigation of pathogenesis as well as the prevention of hyperalgesia. The expression of caspase-6, CCL21 and CXCR3 was also evaluated by RT-qPCR and Western blot. RESULTS: This study discovered mechanical allodynia and thermal hyperalgesia along with the increase in the expression of spinal caspase-6 and CCL21/CXCR3 after remifentanil exposure. Central caspase-6 inhibition prevented behavioral RIH and spinal up-regulation of CCL21/CXCR3 level. Intrathecal anti-CCL21 injection reduced RIH and spinal expression of CXCR3. The delivery of recombinant caspase-6 facilitated acute nociceptive hypersensitivity and increased spinal CXCR3 release in naïve rats, reversing by co-application of anti-CCL21. Also, NBI-74330 attenuated RIH and exogenous CCL21-caused acute pain behaviors. CONCLUSION: This study highlighted that spinal caspase-6-mediated up-regulation of CCL21/CXCR3 is vital in the pathogenesis of RIH in rats.