Excessive exogenous cholesterol activating intestinal LXRα-ABCA1/G5/G8 signaling pathway can not reverse atherosclerosis in ApoE−/− mice

Abstract

Background 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. Methods 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. Results 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. Conclusion 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. Graphical Abstract

Silicon as a Functional Meat Ingredient Improves Jejunal and Hepatic Cholesterol Homeostasis in a Late-Stage Type 2 Diabetes Mellitus Rat Model

“…In addition, LD rats showed downregulation of LXRα/β with respect to ED which in turn reduced levels of ABCG5/8 proteins. LXRα/β-ABCG5/G8 pathway is one of the strategies to regulate intestinal cholesterol homeostasis [ 45 ]. An enhancement of CM secretion in individuals with T2DM has been related to low ABCG5 and ABCG8 mRNA levels [ 46 , 47 ].…”

“…Furthermore, the excess cholesterol removal by HDLc was compromised in LD rats. Jejunal and hepatic ABCA1 levels were lower in LD rats vs. ED rats as a consequence of LXRα/β downregulation [ 45 ]. In addition, significantly lower HDLc levels were found in LD rats (16%, p < 0.01).…”