Basic Study
Copyright ©The Author(s) 2023. Published by Baishideng Publishing Group Inc. All rights reserved.
World J Gastroenterol. Sep 7, 2023; 29(33): 4975-4990
Published online Sep 7, 2023. doi: 10.3748/wjg.v29.i33.4975
Angiotensin-converting enzyme 2 improves liver fibrosis in mice by regulating autophagy of hepatic stellate cells
Ying Wu, Ai-Hong Yin, Jun-Tao Sun, Wei-Hua Xu, Chun-Qing Zhang
Ying Wu, Jun-Tao Sun, Wei-Hua Xu, Department of Gastroenterology, The Second Hospital, Cheeloo College of Medicine, Shandong University, Jinan 250033, Shandong Province, China
Ai-Hong Yin, Department of Gastroenterology, Shandong Second Provincial General Hospital, Jinan 250000, Shandong Province, China
Chun-Qing Zhang, Department of Gastroenterology, Shandong Provincial Hospital, Cheeloo College of Medicine, Shandong University, Jinan 250021, Shandong Province, China
Author contributions: Wu Y, Xu WH, and Zhang CQ designed and coordinated the study; Wu Y, Sun JT, and Yin AH performed the experiments, acquired and analyzed data; Xu WH and Zhang CQ interpreted the data; Wu Y wrote the manuscript; All authors have read and approved the final manuscript.
Supported by Shandong Provincial Natural Science Foundation, No. ZR2021MH389.
Institutional animal care and use committee statement: All animal experiments conformed to the internationally accepted principles for the care and use of laboratory animals, NO. KYLL-2021 (KJ) A-0062, The Institutional Animal Care Committee of the Second Hospital, Cheeloo College of Medicine, Shandong University.
Conflict-of-interest statement: All the authors report no relevant conflicts of interest for this article.
Data sharing statement: No additional data are available.
ARRIVE guidelines statement: The authors have read the ARRIVE Guidelines, and the manuscript was prepared and revised according to the ARRIVE Guidelines.
Open-Access: This article is an open-access article that was selected by an in-house editor and fully peer-reviewed by external reviewers. It is distributed in accordance with the Creative Commons Attribution NonCommercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited and the use is non-commercial. See:
Corresponding author: Wei-Hua Xu, MD, PhD, Chief Doctor, Professor, Department of Gastroenterology, The Second Hospital, Cheeloo College of Medicine, Shandong University, No. 247 Beiyuan Street, Jinan 250033, Shandong Province, China.
Received: May 25, 2023
Peer-review started: May 25, 2023
First decision: July 8, 2023
Revised: July 27, 2023
Accepted: August 15, 2023
Article in press: August 15, 2023
Published online: September 7, 2023

Liver fibrosis is the common pathological process associated with the occurrence and development of various chronic liver diseases. At present, there is still a lack of effective prevention and treatment methods in clinical practice. Hepatic stellate cell (HSC) plays a key role in liver fibrogenesis. In recent years, the study of liver fibrosis targeting HSC autophagy has become a hot spot in this research field. Angiotensin-converting enzyme 2 (ACE2) is a key negative regulator of renin-angiotensin system, and its specific molecular mechanism on autophagy and liver fibrosis needs to be further explored.


To investigate the effect of ACE2 on hepatic fibrosis in mice by regulating HSC autophagy through the Adenosine monophosphate activates protein kinases (AMPK)/mammalian target of rapamycin (mTOR) pathway.


Overexpression of ACE2 in a mouse liver fibrosis model was induced by injection of liver-specific recombinant adeno-associated virus ACE2 vector (rAAV2/8-ACE2). The degree of liver fibrosis was assessed by histopathological staining and the biomarkers in mouse serum were measured by Luminex multifactor analysis. The number of apoptotic HSCs was assessed by terminal deoxynucleoitidyl transferase-mediated dUTP nick-end labeling (TUNEL) and immunofluorescence staining. Transmission electron microscopy was used to identify the changes in the number of HSC autophagosomes. The effect of ACE2 overexpression on autophagy-related proteins was evaluated by multicolor immunofluorescence staining. The expression of autophagy-related indicators and AMPK pathway-related proteins was measured by western blotting.


A mouse model of liver fibrosis was successfully established after 8 wk of intraperitoneal injection of carbon tetrachloride (CCl4). rAAV2/8-ACE2 administration reduced collagen deposition and alleviated the degree of liver fibrosis in mice. The serum levels of platelet-derived growth factor, angiopoietin-2, vascular endothelial growth factor and angiotensin II were decreased, while the levels of interleukin (IL)-10 and angiotensin- (1-7) were increased in the rAAV2/8-ACE2 group. In addition, the expression of alpha-smooth muscle actin, fibronectin, and CD31 was down-regulated in the rAAV2/8-ACE2 group. TUNEL and immunofluorescence staining showed that rAAV2/8-ACE2 injection increased HSC apoptosis. Moreover, rAAV2/8-ACE2 injection notably decreased the number of autophagosomes and the expression of autophagy-related proteins (LC3I, LC3II, Beclin-1), and affected the expression of AMPK pathway-related proteins (AMPK, p-AMPK, p-mTOR).


ACE2 overexpression can inhibit HSC activation and promote cell apoptosis by regulating HSC autophagy through the AMPK/mTOR pathway, thereby alleviating liver fibrosis and hepatic sinusoidal remodeling.

Keywords: Angiotensin-converting enzyme 2, Hepatic stellate cells, Autophagy, Liver fibrosis, Portal hypertension, Mice

Core Tip: Liver fibrosis and cirrhosis are the common outcomes of most chronic liver diseases, and there is a lack of effective treatment at present. Angiotensin-converting enzyme 2 (ACE2), as the main target receptor for the coronavirus disease virus invasion into the human body, is one of the research hotspots. The involvement of autophagy in the activation mechanism of hepatic stellate cell (HSC) during liver fibrosis has attracted increasing attention. Our study found that ACE2 can inhibit the activation and proliferation of HSCs by regulating autophagy, and promote apoptosis of HSCs, providing new ideas for the treatment of liver fibrosis and hepatic sinusoidal remodeling.