黄芪皂苷诱导自噬的抗炎机制研究

Anti-inflammatory namely resist inflammation and evolution，which is the most important way to treat and alleviate inflammatory disease by suppression the immune response to down-regulate excessive inflammation. Astragaloside is identified as an anti-inflammatory agent, which is the most active ingredients extracting from traditional Chinese medicine Astragalus membranaceus. While, autophagy is a fundamental cell biological involving the non-specific bulk degradation of cytoplasmic components and keeping homeostasis of immunocyte, it is a process related to the anti-inflammatory. Our recent study has demonstrated that Bec1, ATG5 were up-regulated dramatically, and autophagosomes were triggered, meanwhile, mRNA levels of proinflammatory cytokines (including TNF-α、IL-1βand IL-6) were crippled in the cell of the model of inflammation induced by nicotine, after treatment with astragaloside. While role of astragaloside in anti-inflammatory was abolished, atfter treatment by inhibitor (CQ) of autophagy . Moreover,Bec-1,ATG5 and LC3-II were induced, pulmonary inflammation of mice induced by smoking was mitigated notably, after intraperitoneal injection astragaloside. We hypothesize that autophagy maybe mediate that anti-inflammatory process was actived by astragaloside. To test this idea，we will investigate signaling transduction pathways of autophagy triggered by astragaloside, as well as the role of autophagy in anti-inflammatory. The current study will clarify a novel pathway in anti-inflammatory depending on astragaloside mediated by autophagy.

抗炎即抵抗炎症的发生和持续，通过抑制免疫应答下调过度的炎症反应，是治疗和缓解炎症性疾病的重要方式。黄芪皂苷作为黄芪的主要有效成分具有抗炎的作用；自噬是有序降解胞内组分的一个保守的生理学过程，被证实具有调节免疫细胞内稳态，参与抑制炎症反应的作用。我们最近的研究表明，在尼古丁刺激的细胞中，经黄芪皂苷处理可以激活自噬基因Bec1、ATG5表达和自噬小体(LC3-GFP)形成，同时下调炎症因子(TNF-α、IL-1β和 IL-6)的mRNA水平；相反，自噬抑制剂氯喹(CQ)处理，能解除黄芪皂苷下调炎症因子的作用。此外，在烟熏诱导炎症的小鼠中，黄芪皂苷也能激活自噬基因Bec-1、ATG5和LC3表达，并显著下调肺部炎症。我们设想，自噬可能参与黄芪皂苷抗炎的过程。本项目以炎症模型的细胞和小鼠为对象，研究自噬在黄芪皂苷抗炎中的作用以及参与其中的信号途径。本研究将揭示一个由自噬介导的黄芪皂苷抗炎的机制。

炎症反应的持续发作、缓慢发生、或潜在毒性物质长期刺激，会造成组织损伤或病变引发严重的炎症性疾病。目前抗炎，是治疗和缓解炎症性疾病的重要方式。黄芪皂苷作为黄芪的主要有效成分具有抗炎的作用，但作用机制尚不完全清楚。而自噬作为一种清道夫机制，通过有序降解胞内组分维持机体内稳态，参与抑制炎症反应的作用。通过项目的研究发现，在香烟提取物（CSE）诱导的细胞模型中筛选不同种类的黄芪皂苷单体，发现黄芪皂苷IV具有显著抗炎的作用，并且能够显著诱导自噬相关基因Atg5、Atg7和LC3-II的表达。通过RNAi敲低自噬基因Atg-7，显著的降低了黄芪皂苷IV的抗炎效果。并且，在细胞和动物实验中，对潜在的参与黄芪皂苷IV激活自噬发挥抗炎作用的信号途径进行筛选后，发现PI3K/Akt、NF-κB、TGFβ/Smads、ERK1/2信号会被激活为潜在的介导自噬抗炎的信号途径，而最后证实过ERK信号途径的抑制剂ISRIB处理后，自噬相关基因Bec-1、LC3-II、ATG5、的mRNA相对表达下降；并且，在动物实验中证实抑制剂ISRIB处理后，自噬基因的表达降低；同时，黄芪甲苷IV下调炎症细胞因子的作用显著降低，初步证明ERK/MAPK信号参与了黄芪皂苷诱导自噬抗炎的过程。