Department of Neurosurgery, Zhejiang University, Hangzhou, Zhejiang, China.
Neurobiol Dis. 2013 Oct;58:296-307. doi: 10.1016/j.nbd.2013.06.011. Epub 2013 Jun 29.
Neuroinflammation contributes to the pathogenesis of early brain injury (EBI) after subarachnoid hemorrhage (SAH). Cytotoxic events following SAH, such as extracellular accumulation of adenosine triphosphate (ATP), may activate the P2X purinoceptor 7 (P2X7R)/cryopyrin inflammasome axis, thus inducing the proinflammatory cytokine IL-1β/IL-18 secretion. We therefore hypothesized that inhibition of P2X7R/cryopyrin inflammasome axis would ameliorate neuroinflammation after SAH. In the present study, SAH was induced by the endovascular perforation in rats. Small interfering RNAs (siRNAs) of P2X7R or cryopyrin were administered intracerebroventricularly 24h before SAH. Brilliant blue G (BBG), a non-competitive antagonist of P2X7R, was administered intraperitoneally 30min following SAH. Post-assessments including SAH severity score, neurobehavioral test, brain water content, Western blot and immunofluorescence, were performed. Administration of P2X7R and cryopyrin siRNA as well as pharmacologic blockade of P2X7R by BBG ameliorated neurological deficits and brain edema at 24h following SAH. Inhibition of P2X7R/cryopyrin inflammasome axis suppressed caspase-1 activation, which subsequently decreased maturation of IL-1β/IL-18. To investigate the link between P2X7R and cryopyrin inflammasome in vivo, Benzoylbenzoyl-ATP (BzATP), a P2X7R agonist, was given to lipopolysaccharide (LPS) primed naive rats with scramble or cryopyrin siRNAs. In LPS-primed naive rats, BzATP induced caspase-1 activation and mature IL-1β release were neutralized by cryopyrin siRNA. Thus, the P2X7R/cryopyrin inflammasome axis may contribute to neuroinflammation via activation of caspase-1 and thereafter mature IL-1β/IL-18 production following SAH. Therapeutic interventions targeting P2X7R/cryopyrin pathway may be a novel approach to ameliorate EBI following SAH.
神经炎症是蛛网膜下腔出血（SAH）后早期脑损伤（EBI）的发病机制之一。SAH 后细胞毒性事件，如细胞外三磷酸腺苷（ATP）的积累，可能会激活 P2X7R/冷球蛋白炎性小体轴，从而诱导促炎细胞因子 IL-1β/IL-18 的分泌。因此，我们假设抑制 P2X7R/冷球蛋白炎性小体轴可改善 SAH 后的神经炎症。在本研究中，通过血管内穿剌法在大鼠中诱导 SAH。在 SAH 前 24 小时，通过脑室内给予 P2X7R 或冷球蛋白的小干扰 RNA（siRNA）。SAH 后 30 分钟，通过腹腔内给予 P2X7R 的非竞争性拮抗剂亮蓝 G（BBG）。进行包括 SAH 严重程度评分、神经行为测试、脑水含量、Western blot 和免疫荧光在内的后评估。给予 P2X7R 和冷球蛋白 siRNA 以及通过 BBG 药理学阻断 P2X7R 可改善 SAH 后 24 小时的神经功能缺损和脑水肿。抑制 P2X7R/冷球蛋白炎性小体轴可抑制半胱天冬酶-1 的激活，进而减少 IL-1β/IL-18 的成熟。为了研究体内 P2X7R 和冷球蛋白炎性小体之间的联系，在 LPS 预处理的给予 scramble 或冷球蛋白 siRNA 的幼稚大鼠中给予苯甲酰基苯甲酰基-ATP（BzATP），一种 P2X7R 激动剂。在 LPS 预处理的幼稚大鼠中，BzATP 诱导的半胱天冬酶-1 激活和成熟的 IL-1β 释放被冷球蛋白 siRNA 中和。因此，P2X7R/冷球蛋白炎性小体轴可能通过激活半胱天冬酶-1 以及随后 SAH 后成熟的 IL-1β/IL-18 产生来促进神经炎症。针对 P2X7R/冷球蛋白途径的治疗干预可能是改善 SAH 后 EBI 的一种新方法。
