基于胆固醇逆转运-跨肠胆固醇排泄的陈皮降脂作用机制研究

Trans-intestinal Cholesterol Efflux(TICE) is the final step of reverse cholesterol transport(RCT)which is of great significance to eliminate excessive cholesterol from the body and maintain cholesterol homeostasis in vivo. Preliminary results showed that Pericarpium Citri Reticultae has significant effect of lipid-lowering, increaseing TC fecal excretion and promoting gene expression of ABCA1, LXRα, PPARγ related to RCT, while no effect on the excretion of fecal bile acid. So, we think that the lipid-lowering effect of Pericarpium Citri Reticultae may be related to the promotion TICE of RCT, so as increase TC excretion from fecas. However the mechanism is not clear and need to be further study. Therefore, this project will take hyperlipidemia model golden hamster induced by high fat diet and Caco-2 cell monolayer transport model as research system, use modern pharmacological methods and molecular biology techniques such as siRNA and slow virus, to observe the effects of Pericarpium Citri Reticultae on RCT and TICE in vivo and in vitro from different levels of external and internal, the effect on the key protein expression of RCT-TICE such as LDLR, VLDLR, LRP, apoER2, ABCG5/G8, ABCB1a/1b. So clarify the mechanism and targets of Pericarpium Citri Reticultae lipid-lowering by TICE. Through this study, it can promote the development and application of Pericarpium Citri Reticulatae in prevention and treatment of hyperlipidemia; develop combination of traditional Chinese and Western Medicine of “regulating Qi-flowing for strengthening spleen, eliminating dampness and phlegm” theory of traditional Chinese Medicine.

跨肠胆固醇排泄（TICE）是胆固醇逆转运（RCT）的最终清除环节之一，对清除体内多余胆固醇（TC）、维持TC稳态平衡具有重要意义。前期研究发现陈皮具有显著降脂作用，并能增加粪便TC排泄和RCT相关调控基因ABCA1、LXRα、PPARγ表达，但对粪便胆汁酸分泌无影响。由此，认为陈皮降脂作用与调节RCT的TICE途径，促进粪便TC排泄有关，但具体作用机制未明。拟以高脂饮食致高脂血症金黄地鼠和Caco-2细胞单层转运模型为研究体系，采用现代药理学手段和siRNA/慢病毒等分子生物学技术，从体内外不同水平观察陈皮对在体和离体RCT、TICE过程的作用及对LDLR、VLDLR、LRP、apoER2、ABCG5/G8、ABCB1a/1b等RCT-TICE关键蛋白表达的影响，明确陈皮调节TICE而降脂的作用机制和靶点。以促进陈皮在防治高脂血症中的开发应用，“理气健脾、燥湿化痰”降脂理论的中西医结合。

高脂血症严重危害人体健康，体内过高的血脂主要通过小肠清除排泄。而小肠胆固醇的清除是胆固醇逆转运（RCT）的最终环节，包括胆汁酸途径和跨肠胆固醇排泄（TICE）。陈皮为理气药具有良好的降血脂作用，但机制不清。本项目旨在研究陈皮促进小肠排泄而降脂的作用特点，明确陈皮促进胆固醇逆转运的TICE途径和胆汁酸途径的降脂机制和具体靶点。体外实验发现，陈皮可促进胆固醇从巨噬细胞流出，促进肝细胞对胆固醇摄取，进而促进胆固醇逆转运。金黄地鼠和大鼠高脂模型的研究，明确了陈皮良好的降血脂作用，还能改善伴随症状。发现陈皮降血脂的作用机制为，增加LXRα-PPARγ/ABCA1/ SR-BI/LDLR通路，促进胆固醇逆转运；增加BSEP、FXR、ABCB1和ABCG5/8，促进胆汁酸途径。但对TICE没有促进作用，表现为小肠ABCB1、ABCG5没有影响，显著降低小肠LDL-R、apoER、LRP、VLDL-R mRNA表达。同时研究了陈皮药效成分-多甲氧基黄酮（PMFs）的降血脂作用及其机制。PMFs可改善高脂血症大鼠的血脂水平，抑制炎症细胞因子和氧化应激，防止饮食诱导的肝脏脂质积累。通过增加LXRα/ABCA1/SR-BI/LDLR促进胆固醇逆转运，通过CYP27A1/CYP7A1/CYP7B1增加胆固醇的代谢，增加BSEP/ABCB1/ABCG5/8表达，促进胆固醇和胆汁酸从肝脏的排泄，并通过ASBT、OSTα/β、NTCP、FGF15、FGFR4调节胆汁酸肠肝循环，维持胆汁酸稳态，调节脂质代谢和保护肝脏。项目的研究进一步明确了陈皮促进RCT的降血脂作用，初步阐明了可能机制，陈皮主要通过胆汁酸途径降脂与其“理气健脾、燥湿化痰”密切相关，赋予中药传统理气药功能新的科学内涵，促进陈皮在防治高脂血症中的开发应用。研究成果已发表论文9篇，其中SCI 2篇；发表国际会议论文（摘要）2篇；培养硕士研究生1名，本科生3名。