Department of Neurology, The First Affiliated Hospital of Chongqing Medical University, 1st You Yi Road, Yu Zhong District, Chongqing, 400016, People's Republic of China.
Laboratory Research Center, The First Affiliated Hospital of Chongqing Medical University, 1st You Yi Road, Yu Zhong District, Chongqing, 400016, People's Republic of China.
J Neuroinflammation. 2019 Apr 10;16(1):78. doi: 10.1186/s12974-019-1459-7.
Central sensitization is an important mechanism of chronic migraine (CM) and is related to the inflammatory response of microglia. The NOD-like receptor protein 3 (NLRP3) inflammasome may regulate the inflammatory process of microglia in several neurological diseases, but its role in CM is largely unknown. Therefore, the aim of this study was to identify the precise role of microglial NLRP3 in CM.
An experimental CM mouse model was established by repeated intraperitoneal (i.p) injection with nitroglycerin (NTG). We evaluated the expression levels of NLRP3 and its downstream interleukin (IL)-1β protein in the trigeminal nucleus caudalis (TNC; which is a central area relevant to migraine pain) at different time points. To further examine the effects of the NLRP3 inflammasome pathway on central sensitization of CM, we examined MCC950, an NLRP3 inflammasome-specific inhibitor, and IL-1ra, an IL-1β antagonist, whether altered NTG-induced mechanical hyperalgesia of the periorbital area and hind paw. The effect of MCC950 and IL-1ra on c-Fos, phosphorylated extracellular signal-regulated kinase (p-ERK) and calcitonin gene-related peptide (CGRP) expression in the TNC were also analyzed. The cell localization of NLRP3 and IL-1β in the TNC was evaluated by immunofluorescence staining.
Repeated NTG administration induced acute and chronic mechanical hyperalgesia and increased expression of NLRP3 and IL-1β. Blockade of NLRP3 or IL-1β reduced NTG-induced hyperalgesia, and this effect was accompanied by a significant inhibition of the NTG-induced increase in p-ERK, c-Fos and CGRP levels in the TNC. Immunofluorescence staining revealed that NLRP3 and IL-1β were mainly expressed in microglia in the TNC, and the IL-1β receptor, IL-1R, was mainly expressed in neurons in the TNC.
These results indicate that NLRP3 activation in the TNC participates in the microglial-neuronal signal by mediating the inflammatory response. This process contributes to the central sensitization observed in CM.
中枢敏化是慢性偏头痛（CM）的一个重要机制，与小胶质细胞的炎症反应有关。NOD 样受体蛋白 3（NLRP3）炎性小体可能调节几种神经疾病中小胶质细胞的炎症过程，但它在 CM 中的作用在很大程度上尚不清楚。因此，本研究旨在确定小胶质细胞 NLRP3 在 CM 中的精确作用。
通过重复腹腔（i.p）注射硝化甘油（NTG）建立实验性 CM 小鼠模型。我们在不同时间点评估了三叉神经尾核（TNC；与偏头痛疼痛相关的中央区域）中 NLRP3 及其下游白细胞介素（IL）-1β蛋白的表达水平。为了进一步研究 NLRP3 炎性小体通路对 CM 中枢敏化的影响，我们检查了 NLRP3 炎性小体特异性抑制剂 MCC950 和 IL-1β拮抗剂 IL-1ra 是否改变了 NTG 诱导的眶周和后爪机械性痛觉过敏。还分析了 MCC950 和 IL-1ra 对 TNC 中 c-Fos、磷酸化细胞外信号调节激酶（p-ERK）和降钙素基因相关肽（CGRP）表达的影响。通过免疫荧光染色评估了 NLRP3 和 IL-1β在 TNC 中的细胞定位。
重复 NTG 给药诱导急性和慢性机械性痛觉过敏，并增加 NLRP3 和 IL-1β 的表达。阻断 NLRP3 或 IL-1β 可减轻 NTG 诱导的痛觉过敏，并且这种作用伴随着 TNC 中 NTG 诱导的 p-ERK、c-Fos 和 CGRP 水平升高的显著抑制。免疫荧光染色显示，NLRP3 和 IL-1β 主要在 TNC 中的小胶质细胞中表达，IL-1β 受体，IL-1R，主要在 TNC 中的神经元中表达。
这些结果表明，TNC 中的 NLRP3 激活通过介导炎症反应参与小胶质细胞-神经元信号传导。该过程有助于观察到的 CM 中的中枢敏化。
