犬尿喹啉酸对NLRP3炎症小体活化及相关炎症疾病的调控作用与机制研究

Aberrant activation of NLRP3 inflammasome leads to various inflammatory diseases, therefore it becomes a potential target for the prevention and treatment of inflammatory diseases. However, the regulatory mechanism of NLRP3 inflammsome activation is still not clear. Our previous studies showed that Kynurenic acid (KYNA), a metabolite of tryptophan, could inhibit NLRP3 activation and attenuate LPS-induced systemic inflammation, which was closely related to the GPR35/β-arrestin-2 signaling pathway activated by KYNA. According to this, we suggest that KYNA inhibits the activation of NLRP3 inflammasome via GPR35 and improves NLRP3 inflammasome-related inflammatory diseases. In this study, we aim to investigate the inhibitory effect of KYNA on the activation of NLRP3 inflammasome, and to elucidate the molecular mechanisms of KYNA against NLRP3 inflammasome by activating GPR35/β-arrestin-2 signaling pathway through in vitro experiments, and finally to determine the therapeutic effect of KYNA on NLRP3 inflammasome-related inflammatory diseases through in vivo experiments. This project will further elucidate the new regulatory mechanisms of the activation of NLRP3 inflammasome and provide new targets for the prevention and treatment of NLRP3 inflammasome-related inflammatory diseases.

NLRP3炎症小体异常活化导致多种炎症疾病，因此其成为炎症疾病防治的潜在靶点，但其活化调控机制仍不甚清楚。我们前期研究发现，色氨酸代谢产物犬尿喹啉酸（Kynurenic acid，KYNA）可抑制NLRP3炎症小体活化并减轻LPS诱导的系统性炎症，其机制与KYNA激活GPR35/β-arrestin-2信号通路密切相关。据此我们推测：KYNA通过GPR35抑制NLRP3炎症小体活化并改善相关炎症疾病。本课题将通过体外实验验证KYNA对NLRP3炎症小体活化的抑制作用，并阐明KYNA通过激活GPR35/β-arrestin-2信号通路抑制NLRP3炎症小体活化的分子机制，最后通过体内实验确定KYNA对NLRP3炎症小体相关炎症疾病的治疗作用。本课题将进一步阐明调控NLRP3炎症小体活化的新机制，并为NLRP3炎症小体相关炎症疾病的防治提供新靶点。

NLRP3炎症小体异常活化导致多种疾病，调控其活化可以避免炎症性疾病。色氨酸代谢物犬尿喹啉酸（KA）具有免疫调节作用，但其对NLRP3炎症小体及其相关疾病的影响尚无研究。因此，本课题旨在研究KA对NLRP3炎症小体活化的调控作用、作用机制及其相关疾病的治疗价值。我们首先构建了不同炎症小体活化体系，发现KA特异性抑制NLRP3炎症小体活化，且对不同刺激剂诱导的NLRP3炎症小体经典活化和非经典活化均有抑制作用。通过对NLRP3炎症小体活化过程的分析，我们发现，KA对NLRP3、ASC及pro-caspase-1的蛋白水平无影响，但抑制ASC寡聚化及ASC与NLRP3的相互作用，说明KA NLRP3炎症小体活化阶段发挥作用。通过分析影响NLRP3活化阶段的胞内信号，我们发现，KA不影响NLRP3刺激剂诱导的钾离子外流，但抑制了胞内钙动员，进而减轻了后续的线粒体损伤并减少线粒体ROS（mtROS）的产生，最终抑制了NLRP3炎症小体活化。通过使用基因缺陷小鼠，我们证实，KA通过结合其受体GPR35来发挥抑制作用。GPR35缺失会削弱KA 对NLRP3炎症小体的抑制作用。另外，用合成的GPR35激动剂也可以有效抑制NLRP3炎症小体活化。通过建立不同的NLRP3炎症小体相关动物疾病模型，我们发现，KA可通过其受体GPR35抑制体内NLRP3炎症小体活化，减少炎症因子的产生，有效减轻LPS诱导的败血症，改善MSU诱导的腹膜炎及高脂饮食引起的组织炎症和代谢紊乱。本研究发现了抑制NLRP3炎症小体活化的新分子和新靶点，为治疗NLRP3 炎症小体相关疾病提供新思路和实验依据。