胆酸对代谢性炎症的调控作用及其机理研究

In recent years, with the rapid development of high density and intensive farming mode in China, more and more cultured animals appear to accumulate large amounts of fat in the body which cause metaflammation. As an endogenous signal molecule, cholic acid can activate the nuclear FXR receptor, which is involved in the regulation of lipid metabolism through a variety of signaling pathways. Based on previous studies, we demonstrated that the cholic acid significantly decreased weight growth of diet obesity model rats, and had a strong inhibitory effect on acute and chronic inflammation. However, the mechanism of cholic acid on the treatment of metabolic inflammation in diet obesity model rats is no entirely clear. Therefore, this study will investigate the effects of cholic acid on the content of Carbohydrate and Lipid metabolism related indicators, the content of inflammatory and chemotactic factor in diet obesity model rats, the mRNA and protein expression of TLR4 receptor, FXR receptor, NF-κB p65, COX-2 in mouse peritoneal macrophages using automatic biochemical analysis, ELISA and qPCR, Western blot and other methods. Aimed to investigate the effect of cholic acid on TLR4- FXR- NF-κB Signaling pathway in peritoneal macrophages. The molecular regulation mechanism of cholic acid on metabolism inflammatory will be revealed. So as to provide theoretical and experimental basis for the functional feed additives and the new products improving lipid metabolism.

近年来，随着我国高密度、集约化养殖模式的快速发展，越来越多的养殖动物出现脂肪在体内大量蓄积，从而触发代谢性炎症。胆酸作为一种内源性信号分子可以激活细胞核FXR受体，通过多种信号途径参与脂代谢的调节。我们的前期研究发现，胆酸能明显抑制营养性肥胖模型大鼠体重增长速度，且对急、慢性炎症均有很强的抑制作用，而胆酸对代谢性炎症的调控作用机理目前尚不完全清楚。为此，本研究拟采用全自动生化分析法、ELISA和qPCR、Western blot等方法，测定代谢性炎症模型小鼠糖、脂代谢相关指标、炎症因子、趋化因子等含量和小鼠腹腔巨噬细胞TLR4受体、FXR受体、NF-κB p65、COX-2 mRNA及蛋白表达。旨在探讨胆酸对小鼠腹腔巨噬细胞TLR4- FXR- NF-κB信号通路的影响，深入揭示胆酸对代谢性炎症的分子调控机理，从而为研究功能性饲料添加剂及改善脂代谢等新产品的作用靶点提供理论基础和实验依据。

为了探讨胆酸（CA）对代谢性炎症的调控作用机理，寻找胆酸抗代谢性炎症的药理学基础，本研究应用胆酸在体内干预代谢性炎症模型大鼠，体外干预棕榈酸（PA）诱导的大鼠肝脏细胞系（BRL）、TLR4敲除的小鼠腹腔巨噬细胞，阐明胆酸改善代谢性炎症的作用机制。.主要研究内容包括：基于转录组探究胆酸对代谢性炎症的相关机制，胆酸对代谢性炎症模型大鼠糖脂代谢的影响，胆酸对棕榈酸（PA）诱导大鼠肝脏细胞系（BRL）脂代谢的影响，胆酸对小鼠腹腔巨噬细胞TLR4受体-FXR受体-NF-κB信号转导通路的影响。.结果表明：高脂饲料连续喂养60d成功建立代谢性炎症大鼠模型，肝脏组织HE染色证明造模成功。代谢性炎症模型大鼠在CA处理后肝脏转录组学结果显示，差异基因的GO富集主要为结合蛋白、酶调节蛋白及参与氧化应激、脂质和固醇代谢的蛋白，KEGG富集主要为视黄醇和固醇的代谢通路、PPAR通路；大鼠血清代谢组学结果，差异代谢物主要富集于胆固醇、视黄醇、嘌呤、氨基酸等代谢通路，并与差异基因CYP7A1、PPARα、FASN、PAK2、CYP1A2等相关联。PPARα及LXRα受体均分布在肝细胞核。CA干预代谢性炎症模型大鼠，对增重率、WAT、TBA、AST，TG、FFA、糖耐量、胰岛素耐量等相关生理指标均有明显改善，显著降低IL-6、MCP-1含量及MIP-1α、TNF-α、IL-10及IL-8基因表达。200μM PA处理12h建立BRL细胞高脂模型，CA干预PPARα敲除的高脂细胞后，能显著降低LXRα和升高CYP7A1基因及蛋白表达。CA干预PM细胞后，能极显著降低TLR4和极显著升高FXRα基因表达；CA能显著降低LPS处理的PM细胞中TNFα、IL-6、MCP-1、MIP-1c及NF-κB p65的基因表达，但在TLR4敲除的PM细胞中，相关的炎症免疫反应及CA的作用皆被减弱。该研究结果为揭示CA抗代谢性炎症作用的分子机制提供了试验依据。