Attenuation of mechanical pain hypersensitivity by treatment with Peptide5, a connexin-43 mimetic peptide, involves inhibition of NLRP3 inflammasome in nerve-injured mice
Attenuation of mechanical pain hypersensitivity by treatment with Peptide5, a connexin-43 mimetic peptide, involves inhibition of NLRP3 inflammasome in nerve-injured mice
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DOI：
10.1016/j.expneurol.2017.10.016
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发表时间：
2018-02-01
影响因子：
5.3
通讯作者：
Moalem-Taylor, Gila
中科院分区：
文献类型：
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作者：
Tonkin, Ryan S.;Bowles, Callum;Moalem-Taylor, Gila
脊髓星形胶质细胞中的 Connexin43 (Cx43) 半通道与周围神经损伤后神经性疼痛的维持有关。 Peptide5 是一种 Cx43 模拟肽，可阻断半通道。在这项研究中，我们研究了 Peptide5 的脊髓递送对两种神经性疼痛、周围神经损伤和化疗引起的周围神经病变 (CIPN) 小鼠模型的机械性疼痛超敏反应的影响。我们证明，坐骨神经慢性压迫性损伤 (CCI) 10 天后，主要与星形胶质细胞共定位的 Cx43 表达在同侧 L3-L5 腰脊髓中增加。第 10 天，当疼痛已完全确定时，将 Peptide5 鞘内注射到神经损伤的小鼠体内，注射后 8 小时，机械性疼痛过敏性显着改善。与对照盐水处理的CCI小鼠相比，肽5处理导致脊髓背角的Cx43、小胶质细胞和星形胶质细胞活性显着降低。对原代星形胶质细胞培养物的进一步体外研究表明，用 Peptide5 预处理 1 小时可显着减少细胞外钙消耗时三磷酸腺苷 (ATP) 的释放。由于 ATP 是 NOD 样受体蛋白 3 (NLRP3) 炎性体复合物（神经炎症的关键介质）的已知激活剂，因此我们检查了 Peptide5 治疗对 NLRP3 炎性体表达的影响。我们发现 CCI 小鼠同侧脊髓中的 NLRP3、其接头凋亡相关类样蛋白 (ASC) 和 caspase-1 蛋白增加，并在 Peptide5 治疗后降低至初始水平。在奥沙利铂和紫杉醇诱导的周围神经病变模型中，Peptide5 治疗对机械性疼痛超敏反应没有影响。有趣的是，在这些 CIPN 模型中，尽管化疗后第 13 天脊髓 Cx43 表达显着增加，但 NLRP3 表达没有改变。这些结果表明Peptide5的镇痛作用是通过降低NLRP3的表达而特异性实现的。总之，我们的研究结果表明，在神经损伤后用 Peptide5 阻断 Cx43 半通道可以通过特异性靶向脊髓中的 NLRP3 炎性体来减轻机械性疼痛超敏反应。
Connexin43 (Cx43) hemichannels in spinal cord astrocytes are implicated in the maintenance of neuropathic pain following peripheral nerve injury. Peptide5 is a Cx43 mimetic peptide that blocks hemichannels. In this study, we investigated the effects of spinal delivery of Peptide5 on mechanical pain hypersensitivity in two mouse models of neuropathic pain, peripheral nerve injury and chemotherapy-induced peripheral neuropathy (CIPN). We demonstrated that 10 days following a chronic constriction injury (CCI) of the sciatic nerve, Cx43 expression, co-localised predominantly with astrocytes, was increased in the ipsilateral L3-L5 lumbar spinal cord. An intrathecal injection of Peptide5 into nerve-injured mice, on day 10 when pain was well-established, caused significant improvement in mechanical pain hypersensitivity 8 h after injection. Peptide5 treatment resulted in significantly reduced Cx43, and microglial and astrocyte activity in the dorsal horn of the spinal cord, as compared to control saline-treated CCI mice. Further in vitro investigations on primary astrocyte cultures showed that 1 h pre-treatment with Peptide5 significantly reduced adenosine triphosphate (ATP) release in response to extracellular calcium depletion. Since ATP is a known activator of the NOD-like receptor protein 3 (NLRP3) inflammasome complex, a key mediator of neuroinflammation, we examined the effects of Peptide5 treatment on NLRP3 inflammasome expression. We found that NLRP3, its adaptor apoptosis-associated spec-like protein (ASC) and caspase-1 protein were increased in the ipsilateral spinal cord of CCI mice and reduced to naive levels following Peptide5 treatment. In the models of oxaliplatin- and paclitaxel-induced peripheral neuropathy, treatment with Peptide5 had no effect on mechanical pain hypersensitivity. Interestingly, in these CIPN models, although spinal Cx43 expression was significantly increased at day 13 following chemotherapy, NLRP3 expression was not altered. These results suggest that the analgesic effect of Peptide5 is specifically achieved by reducing NLRP3 expression. Together, our findings demonstrate that blocking Cx43 hemichannels with Peptide5 after nerve injury attenuates mechanical pain hypersensitivity by specifically targeting the NLRP3 inflammasome in the spinal cord.