基于甜味受体探索甘味补气中药的免疫调节作用机制

Qi-tonifying Chinese Medicine have definite immunomodulatory effect, and its active ingredient is polysaccharide, but its receptor and mechanism are still unclear. Recent studies showed that sweet receptor of G protein-coupled receptor family not only exist on taste buds, but also express in immune organs and cells. Preliminary experiments showed that sweet receptor could regulate the immune function of macrophages and mice positively and negatively. Besides, the sweet receptor blockers could inhibit the immune enhancement of Astragalus Polysaccharides in mice and macrophages. Combined with the results of the study that Astragalus polysaccharides can regulate immune function by G protein-coupled receptor, the hypothesis of this topic is that sweet receptor is the target ofQi-tonifying Chinese Medicine to exert immune regulation function. This project intends to verify the above hypothesis from two aspects: 1) Applying agonists and inhibitors to verify whether sweet receptors have immunomodulatory effects in sweet receptor knockout or overexpression mice and macrophages; 2) Applying seven kinds of polysaccharides to intervene the immunity sweet receptor knockout or overexpression mice and macrophages, to verify whether sweet receptor is the target of tonifying Qi-tonifying Chinese Medicine for immunomodulatory effects. This project is the first time to explore the relationship between Qi-tonifying Chinese Medicine and sweet receptor. The results of this study will provide a new explanation for the mechanism of immune regulation of Qi-tonifying Chinese Medicine, and provide a modern experimental basis for the “Ganbu” properties of Qi-tonifying Chinese Medicine in another aspect.

甘味补气中药具有确切的免疫调节作用，且活性成分为多糖已被公认，但其作用的受体及机制尚不清楚。近期文献报道G蛋白偶联受体家族的甜味受体不仅存在味蕾，还表达于免疫器官和细胞。预实验显示：甜味受体可正负调控巨噬细胞和小鼠免疫功能，且甜味受体阻断剂能抑制黄芪多糖对小鼠和巨噬细胞的免疫增强作用。结合黄芪等多糖可经G蛋白偶联受体调控免疫功能的研究结果，本课题假说：甜味受体是甘味补气中药调节免疫功能的作用靶点。本项目拟从两个方面验证上述假说：①在甜味受体敲除或过表达的小鼠及巨噬细胞中，利用激动剂与抑制剂验证甜味受体是否具有调节免疫功能的作用；②以7种补气中药多糖干预甜味受体敲除或过表达的小鼠及巨噬细胞，验证甜味受体是否是补气中药调节免疫的作用靶点。本课题首次探索甘味补气中药与甜味受体的相关性。研究结果将为甘味补气中药的免疫调节机制提供新的阐释，且在一定程度上为补气中药的“甘补”药性提供现代实验依据。

甘补中药多糖具确切免疫调节作用，但其作用受体及机制不清。甜味受体表达于免疫器官和细胞，且具调控巨噬细胞吞噬功能苗头。故本项目从甜味受体出发，将多糖经甜味受体调节免疫功能与补气中药的“甘补”药性相结合，以期为补气中药“甘补”药性的科学性提供实验依据。本项目首先探讨了甜味受体是否具调控免疫功能作用及其机制，在此基础上继续探究了黄芪等多糖是否经甜味受体调控免疫功能。研究结果显示：甜味受体及其下游信号分子的基因和蛋白均表达于小鼠巨噬细胞，且甜味受体可经PKC/ERK1/2和PKC/RhoA/ROCK1信号通路调控巨噬细胞吞噬、迁移及骨架蛋白重塑功能；荧光标记黄芪多糖与巨噬细胞结合实验提示其可与巨噬细胞膜蛋白结合发挥效应；黄芪多糖可经甜味受体调控体内外小鼠巨噬细胞免疫功能，且其主要经PKC/RhoA/ROCK1调控巨噬细胞吞噬、迁移及骨架蛋白重塑功能。上述研究结果论证了“多糖-甜味受体-免疫增强作用”之间的生物学效应关系，可为黄芪“甘补”药性的科学性提供实验依据。

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