School of Pharmacy, Nanjing University of Chinese Medicine, Nanjing, 210023, China.
National Standard Laboratory of Pharmacology of Chinese Materia Medica, Nanjing University of Chinese Medicine, Nanjing, 210023, China.
Lipids Health Dis. 2023 Apr 15;22(1):51. doi: 10.1186/s12944-023-01810-6.
The long-term excessive intake of exogenous cholesterol can lead to abnormally elevated blood lipid levels and induce cardiovascular and cerebrovascular diseases. However, the influence and relevance of exogenous cholesterol on plasma cholesterol components were still unclear, and the influence on intestinal lipid metabolism targets needs to be further explored.
In vivo, the C57BL/6 + NF group and ApoE + NF group mice were fed a normal specific pathogen-free (SPF) diet; the ApoE + HF group mice were fed a high-cholesterol SPF diet. The plasma and jejunum tissue homogenate were obtained for non-targeted lipid metabolomics. The lipid droplets in tissues were observed by transmission electron microscope and oil red O staining. Jejunum tissue morphology was observed by HE staining. The kits were used to detect lipid content in plasma, tissues, intestinal contents, and cells. Western blot, RT-PCR, immunohistochemistry (IHC), and immunofluorescence (IF) were used to observe the key target of lipid metabolism. In vitro, the final concentration of cholesterol was 100 μmol/L in Caco-cells. Oil red O staining, western blot, RT-PCR and immunofluorescence (IF) were used to observe the changes of lipid metabolism. Finally, the influence of liver X receptor alpha (LXRα) on intestinal cholesterol metabolism was clarified by applying the LXRα inhibitor GSK2033 and siRNA targeting LXRα.
The aortic arch and intestinal villi of the two groups of ApoE mice showed apparent lesions and lipid accumulation, and there were significant changes in a variety of lipids in the plasma and jejunum. Additionally, jejunum LXRα was markedly activated. High cholesterol can significantly activate LXRα in Caco-2 cells. After LXRα was inhibited, the protein level of ATP-binding cassette transporter A1/G5/G8 (ABCA1/G5/G8) decreased, and the quantity and volume of intracellular lipids soared.
In a high-cholesterol environment, the intestine promotes the excretion of cholesterol from the cell through the LXRα-ABCA1/G5/G8 pathway, reduces the intestinal intake of a variety of exogenous cholesterol, and reduces the risk of AS.
长期过量摄入外源性胆固醇会导致血脂水平异常升高，从而诱发心脑血管疾病。然而，外源性胆固醇对血浆胆固醇成分的影响及其相关性尚不清楚，其对肠道脂质代谢靶点的影响需要进一步探索。
体内，C57BL/6+NF 组和 ApoE+NF 组小鼠给予普通特定病原体无（SPF）饮食；ApoE+HF 组小鼠给予高胆固醇 SPF 饮食。获取血浆和空肠组织匀浆进行非靶向脂质代谢组学分析。透射电镜和油红 O 染色观察组织中的脂滴。HE 染色观察空肠组织形态。试剂盒检测血浆、组织、肠内容物和细胞中的脂质含量。Western blot、RT-PCR、免疫组化（IHC）和免疫荧光（IF）观察脂质代谢关键靶点。体外，Caco-细胞中胆固醇终浓度为 100μmol/L。油红 O 染色、Western blot、RT-PCR 和免疫荧光（IF）观察脂质代谢变化。最后，应用肝 X 受体α（LXRα）抑制剂 GSK2033 和 LXRα 靶向 siRNA 阐明 LXRα 对肠道胆固醇代谢的影响。
两组 ApoE 小鼠的主动脉弓和肠绒毛均出现明显病变和脂质堆积，血浆和空肠中多种脂质均发生明显变化。此外，空肠 LXRα 明显激活。高胆固醇可显著激活 Caco-2 细胞中的 LXRα。抑制 LXRα 后，ABCA1/G5/G8 蛋白水平降低，细胞内脂质数量和体积增加。
在高胆固醇环境中，肠道通过 LXRα-ABCA1/G5/G8 途径促进细胞内胆固醇排出，减少多种外源性胆固醇的肠道摄取，降低 AS 风险。
