INT-777 通过 TGR5/cAMP/PKA 信号通路减轻大鼠蛛网膜下腔出血后 NLRP3-ASC 炎性小体介导的神经炎症。
INT-777 attenuates NLRP3-ASC inflammasome-mediated neuroinflammation via TGR5/cAMP/PKA signaling pathway after subarachnoid hemorrhage in rats.
机构信息
Department of Neurology, Guizhou Provincial People's Hospital, Guiyang, Guizhou 550002, China; Department of Physiology and Pharmacology, Loma Linda University, Loma Linda, CA 92350, USA.
Department of Physiology and Pharmacology, Loma Linda University, Loma Linda, CA 92350, USA; Department of Neurosurgery, Guangxi Medical University Cancer Hospital, Nanning, Guangxi 530021, China.
出版信息
Brain Behav Immun. 2021 Jan;91:587-600. doi: 10.1016/j.bbi.2020.09.016. Epub 2020 Sep 19.
BACKGROUND
Inflammasome-mediated neuroinflammation plays an important role in the pathogenesis of early brain injury (EBI) following subarachnoid hemorrhage (SAH). The activation of the TGR5 receptor has been shown to be neuroprotective in a variety of neurological diseases. This study aimed to investigate the effects of the specific synthetic TGR5 agonist, INT-777, in attenuating NLRP3-ASC inflammasome activation and reducing neuroinflammation after SAH.
METHODS
One hundred and eighty-four male Sprague Dawley rats were used. SAH was induced by the endovascular perforation. INT-777 was administered intranasally at 1 h after SAH induction. To elucidate the signaling pathway involved in the effect of INT-777 on inflammasome activation during EBI, TGR5 knockout CRISPR and PKA inhibitor H89 were administered intracerebroventricularly and intraperitoneally at 48 h and 1 h before SAH. The SAH grade, short- and long-term neurobehavioral assessments, brain water content, western blot, immunofluorescence staining, and Nissl staining were performed.
RESULTS
The expressions of endogenous TGR5, p-PKA, and NLRP3-ASC inflammasome were increased after SAH. INT-777 administration significantly decreased NLRP3-ASC inflammasome activation in microglia, reduced brain edema and neuroinflammation, leading to improved short-term neurobehavioral functions at 24 h after SAH. The administration of TGR5 CRISPR or PKA inhibitor (H89) abolished the anti-inflammation effects of INT-777, on NLRP3-ASC inflammasome, pro-inflammatory cytokines (IL-6, IL-1β, and TNF-a), and neutrophil infiltration at 24 h after SAH. Moreover, early administration of INT-777 attenuated neuronal degeneration in hippocampus on 28 d after SAH.
CONCLUSIONS
INT-777 attenuated NLRP3-ASC inflammasome-dependent neuroinflammation in the EBI after SAH, partially via TGR5/cAMP/PKA signaling pathway. Early administration of INT-777 may serve as a potential therapeutic strategy for EBI management in the setting of SAH.
背景
炎性小体介导的神经炎症在蛛网膜下腔出血（SAH）后早期脑损伤（EBI）的发病机制中起重要作用。TGR5 受体的激活已被证明在多种神经疾病中具有神经保护作用。本研究旨在探讨特异性合成 TGR5 激动剂 INT-777 减轻 SAH 后 NLRP3-ASC 炎性小体激活和减少神经炎症的作用。
方法
使用 184 只雄性 Sprague Dawley 大鼠。通过血管内穿孔诱导 SAH。在 SAH 诱导后 1 小时通过鼻内给予 INT-777。为了阐明 INT-777 对 EBI 期间炎性小体激活的作用涉及的信号通路，在 SAH 前 48 小时和 1 小时通过脑室内和腹腔内给予 TGR5 敲除 CRISPR 和 PKA 抑制剂 H89。进行 SAH 分级、短期和长期神经行为评估、脑水含量、western blot、免疫荧光染色和尼氏染色。
结果
SAH 后内源性 TGR5、p-PKA 和 NLRP3-ASC 炎性小体的表达增加。INT-777 给药可显著降低小胶质细胞中 NLRP3-ASC 炎性小体的激活，减少脑水肿和神经炎症，导致 SAH 后 24 小时短期神经行为功能改善。给予 TGR5 CRISPR 或 PKA 抑制剂（H89）可消除 INT-777 对 NLRP3-ASC 炎性小体、促炎细胞因子（IL-6、IL-1β 和 TNF-a）和中性粒细胞浸润的抗炎作用，SAH 后 24 小时。此外，INT-777 的早期给药可减轻 SAH 后 28 天海马神经元变性。
结论
INT-777 减轻了 SAH 后 EBI 中 NLRP3-ASC 炎性小体依赖性神经炎症，部分通过 TGR5/cAMP/PKA 信号通路。INT-777 的早期给药可能是 SAH 背景下 EBI 管理的一种潜在治疗策略。
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