Aloe-emodin exerts cholesterol-lowering effects by inhibiting proprotein convertase subtilisin/kexin type 9 in hyperlipidemic rats

Zhen-li Su1, Peng-zhou Hang1,2, Juan Hu1, Yu-yang Zheng1, Han-qi Sun1, Jing Guo1, Ke-yu Liu1, Zhi-min Du1,2,3
1 Institute of Clinical Pharmacology, The Second Affiliated Hospital of Harbin Medical University (University Key Laboratory of Drug Research, Heilongjiang Province), Harbin 150086, China
2 Department of Clinical Pharmacology, College of Pharmacy, Harbin Medical University, Harbin 150081, China
3 State Key Laboratory of Quality Research in Chinese Medicines, Macau University of Science and Technology, Macau 999078, China
Correspondence to: Zhi-min Du:,
DOI: 10.1038/s41401-020-0392-8
Received: 11 October 2019
Accepted: 24 February 2020
Advance online: 18 March 2020


Hyperlipidemia (HPL) characterized by metabolic disorder of lipids and cholesterol is one of the important risk factors for cardiovascular diseases. Proprotein convertase subtilisin/kexin type 9 (PCSK9) is a potent circulating regulator of LDL through its ability to induce degradation of the low-density lipoprotein cholesterol receptor (LDLR) in the lysosome of hepatocytes. Aloeemodin (AE) is one of potentially bioactive components of Chinese traditional medicine Daming capsule. In this study we evaluated the HPL-lowering efficacy of AE in both in vivo and in vitro HPL models. High-fat diet-induced rats were treated with AE (100 mg/kg per day, ig) for 6 weeks. We found that AE administration significantly decreased the levels of total cholesterol (TC) and LDL in the serum and liver tissues. Moreover, AE administration ameliorated HPL-induced hepatic lipid aggregation. But AE administration did not significantly inhibit HMG-CoA reductase activity in the liver of HPL rats. A cellular model of HPL was established in human hepatoma (HepG2) cells treated with cholesterol (20 μg/mL) and 25-hydroxycholesterol (2 μg/mL), which exhibited markedly elevated cholesterol levels. The increased cholesterol levels could be reversed by subsequent treatment with AE (30 μM). In both the in vivo and in vitro HPL models, we revealed that AE selectively suppressed the sterol-regulatory element-binding protein-2 (SREBP-2) and hepatocyte nuclear factor (HNF)1α-mediated PCSK9 signaling, which in turn upregulated LDL receptor (LDLR) and promoted LDL uptake. This study demonstrates that AE reduces cholesterol content in HPL rats by inhibiting the hepatic PCSK9/ LDLR pathway.
Keywords: aloe-emodin; hyperlipidemia; cholesterol; PCSK9; LDL receptor; HepG2 cells; atorvastatin

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