Basic Study
Copyright ©The Author(s) 2018. Published by Baishideng Publishing Group Inc. All rights reserved.
World J Gastroenterol. Mar 7, 2018; 24(9): 992-1003
Published online Mar 7, 2018. doi: 10.3748/wjg.v24.i9.992
Autophagy activation by Jiang Zhi Granule protects against metabolic stress-induced hepatocyte injury
Yi-Yuan Zheng, Miao Wang, Xiang-Bing Shu, Pei-Yong Zheng, Guang Ji
Yi-Yuan Zheng, Miao Wang, Xiang-Bing Shu, Pei-Yong Zheng, Guang Ji, Institute of Digestive Disease, Longhua Hospital, Shanghai University of Traditional Chinese Medicine, Shanghai 200032, China
Author contributions: Zheng YY and Wang M contributed equally as co-first authors; Zheng YY and Wang M performed the majority of experiments and drafted the article; Shu XB established the animal model; Zheng PY analyzed the data; Ji G designed the research; all authors approved the final version of the article to be published.
Supported by the National Natural Science Foundation of China, No. 81370092.
Institutional review board statement: This study was reviewed and approved by the Institutional Review Board of Institute of Digestive Disease, Shanghai University of Traditional Chinese Medicine, Shanghai, China.
Institutional animal care and use committee statement: All procedures involving animals were reviewed and approved by the Institutional Animal Care and Use Committee of Shanghai University of Traditional Chinese Medicine (IACUC protocol number Approval number: SZY201508004).
Conflict-of-interest statement: All authors declare that they have no conflicts of interest.
Data sharing statement: No additional data are available.
Open-Access: This article is an open-access article which was selected by an in-house editor and fully peer-reviewed by external reviewers. It is distributed in accordance with the Creative Commons Attribution Non Commercial (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: http://creativecommons.org/licenses/by-nc/4.0/
Correspondence to: Guang Ji, PhD, Chief Doctor, Professor, Institute of Digestive Disease, Longhua Hospital, Shanghai University of Traditional Chinese Medicine, No. 725 South Wanping Road, Shanghai 200032, China. jiliver@vip.sina.com
Telephone: +86-21-64385700 Fax: +86-21-64385700
Received: November 9, 2017
Peer-review started: November 10, 2017
First decision: December 13, 2017
Revised: December 22, 2017
Accepted: January 1, 2018
Article in press: January 1, 2018
Published online: March 7, 2018
Processing time: 116 Days and 1.2 Hours
Abstract
AIM

To elucidate the potential role of autophagy and the protective effects of Jiang Zhi Granule (JZG) in metabolic stress-induced hepatocyte injury.

METHODS

An in vitro and in vivo approach was used in this study. HepG2 cells were incubated in culture medium containing palmitate (PA; 0, 0.1, 0.2, 0.3, 0.4 or 0.5 mmol/L) and treated with or without JZG (100 μg/mL) for 24 h or 48 h, and the progression of autophagy was visualized by stable fluorescence-expressing cell lines LC3 and p62. Western blot analyses were performed to examine the expression of LC3-II/LC3-I, p62, mTOR and PI3K, while mitochondrial integrity and oxidative stress were observed by fluorescence staining of JC-1 and reactive oxygen species. C57BL/6 mice were divided into three groups: control group (n = 10), high fat (HF) group (n = 13) and JZG group (n = 13); and, histological staining was carried out to detect inflammation and lipid content in the liver.

RESULTS

The cell trauma induced by PA was aggravated in a dose- and time-dependent manner, and hepatic function was improved by JZG. PA had dual effects on autophagy by activating autophagy induction and blocking autophagic flux. The PI3K-AKT-mTOR signaling pathway and the fusion of isolated hepatic autophagosomes and lysosomes were critically involved in this process. JZG activated autophagy progression by either induction of autophagosomes or co-localization of autophagosomes and lysosomes as well as degradation of autolysosomes to protect against PA-induced hepatocyte injury, and protected mitochondrial integrity against oxidative stress in PA-induced mitochondrial dysfunction. In addition, JZG ameliorated lipid droplets and inflammation induced by HF diet in vivo, leading to improved metabolic disorder and associated liver injury in a mouse model of non-alcoholic fatty liver disease (NAFLD).

CONCLUSION

Metabolic stress-induced hepatocyte injury exhibited dual effects on autophagy and JZG activated the entire process, resulting in beneficial effects in NAFLD.

Keywords: Autophagy; PI3K-AKT-mTOR signaling pathway; Autophagic flux; Oxidative stress; Hepatocyte injury; Non-alcoholic fatty liver disease

Core tip: Non-alcoholic fatty liver disease (NAFLD), which is mainly characterized by the accumulation of lipids and energy metabolism dysfunction, is now one of the most common risk factors worldwide. As studies have demonstrated that autophagy is important in the maintenance of normal hepatocyte function and in the response to pathogenic changes, we examined the potential role of autophagy in metabolic stress-induced hepatocyte injury. The results showed that metabolic stress had dual effects on autophagy, resulting in autophagy induction and autophagic flux inhibition. The Chinese herbal formula Jiang Zhi Granule activated the autophagy process to protect against metabolic stress-induced hepatocyte injury in NAFLD.