胰岛素诱导基因1（Insig1）对NLRP3炎性小体活化及脓毒症病程进展的影响

Uncontrolled inflammation is a key pathophysiological characteristic of sepsis. Studies have shown that NLRP3 inflammasome play an important role in triggering excessive inflammatory responses, but the underlying mechanisms are not yet fully elucidated. Insulin induced gene 1 (Insig1) is a differential gene identified by high-throughput screening method, the expression of which is significantly down-regulated in sepsis. Our preliminary study found that, the expression of NLRP3, IL-1β and endoplasmic reticulum (ER) stress associated proteins is increased in macrophages after genetic disruption of Insig1. Since Insig1 localizes to ER membrane, and there is a strong correlation between ER stress and NLRP3 inflammasome activation, we propose the hypothesis that the activation of NLRP3 inflammasome is induced by the loss of Insig1 via ER stress signaling pathway, which then cause an uncontrolled inflammation associated with sepsis. Therefore, this project aims to clarify the correlation between Insig1 abnormal expression and sepsis; and to elucidate the effects of Insig1 on NLRP3 inflammasome activation and its molecular mechanism; and to further evaluate the curative effect of ER stress inhibitor in septic mice model. Taken together, this study will increase our knowledge of the pathogenetic mechanisms of sepsis, and provide the experimental and theoretical basis for finding an effective treatment.

炎症失控是脓毒症的关键病理生理特征。研究表明，NLRP3炎性小体活化是导致炎症反应过度的重要原因，但其活化机制尚待明确。胰岛素诱导基因1（Insig1）是我们应用高通量筛选技术发现的，在脓毒症中显著下调的差异基因。前期研究发现，干扰Insig1可以促进巨噬细胞表达NLRP3和IL-1β，同时上调内质网应激相关分子的水平。鉴于Insig1是内质网膜蛋白，而内质网应激反应与NLRP3炎性小体活化密切相关。因此，我们提出如下科学假说：Insig1异常表达诱发内质网应激反应，从而激活NLRP3炎性小体，导致炎症失控和脓毒症发生。本项目拟进一步明确Insig1异常表达与脓毒症的相关性；阐明Insig1对NLRP3炎性小体活化的调控作用及其分子机制；同时评估内质网应激反应抑制剂在脓毒症中的疗效。本研究将完善对脓毒症发病机制的认识，为寻找有效的干预手段提供理论及实验依据。

脓毒症是导致儿童死亡的常见危重病，发病机制至今仍未明确。前期研究发现，脂代谢关键调控分子Insig1在脓毒症中表达发生显著改变。本项目旨在进一步明确Insig1与儿童脓毒症的临床相关性，阐明Insig1对炎症反应，特别是NLRP3炎性小体的调控作用及其分子机制，为深入了解Insig1在脓毒症发病过程中的作用提供实验依据。本项目分别从Insig1与脓毒症的临床相关性，Insig1对NLRP3炎性小体活化的影响，Insig1调控NLRP3炎性小体的相关分子机制三个方面展开研究。结果显示，Insig1在脓毒症儿童和脓毒症小鼠中均明显降低，其表达水平与疾病病情密切相关。体外干扰巨噬细胞Insig1可以促进NLRP3炎性小体活化，上调IL-1的表达，且该过程依赖caspase-1信号活化。过表达Insig1可以抑制LPS/ATP介导的IL-1分泌。此外，干扰Insig1后，经内质网应激反应抑制剂4-PBA可以明显降低LPS/ATP介导的IL-1分泌，且呈剂量依赖性。这表明，Insig1可通过内质网应激信号调控NLRP3炎性小体活化以及IL-1表达。. 综上所述，本项目发现Insig1在儿童脓毒症中存在异常低表达，并提出“Insig1可能通过内质网应激反应激活NLRP3炎性小体，促进IL-1分泌，从而加重炎症，推动脓毒症病情发展”这一调节模式。本项目研究结果将有助于进一步阐明脓毒症炎症失控的分子机制，为寻找脓毒症，特别是儿童脓毒症诊治新靶标提供实验依据。