Basic Study
Copyright ©The Author(s) 2020. Published by Baishideng Publishing Group Inc. All rights reserved.
World J Gastroenterol. Dec 14, 2020; 26(46): 7299-7311
Published online Dec 14, 2020. doi: 10.3748/wjg.v26.i46.7299
Untargeted metabolomics characteristics of nonobese nonalcoholic fatty liver disease induced by high-temperature-processed feed in Sprague-Dawley rats
Li-Jun Xue, Ju-Qiang Han, Yuan-Chen Zhou, Hong-Ye Peng, Teng-Fei Yin, Kai-Min Li, Shu-Kun Yao
Li-Jun Xue, Shu-Kun Yao, School of Biological Science and Medical Engineering, Beihang University, Beijing 100191, China
Ju-Qiang Han, Department of Hepatology, The Seventh Medical Center of PLA General Hospital, Beijing 100700, China
Yuan-Chen Zhou, Hong-Ye Peng, Teng-Fei Yin, Kai-Min Li, Shu-Kun Yao, Department of Gastroenterology, China-Japan Friendship Hospital, Beijing 100029, China
Author contributions: Xue LJ, Zhou YC, Peng HY and Yin TF performed the experiments; Xue LJ analyzed the data, prepared figures and contributed to the drafting of the manuscript; Yao SK and Han JQ supervised this work and edited and revised manuscript; Yao SK initiated the project, design the experiments and approved the final version of manuscript; Li KM provided technical assistance; All authors read and approved the final manuscript.
Supported by Science and Technology Project Task Book of Beijing, No. Z171100001717008.
Institutional animal care and use committee statement: The study was approved by the Animal Care Committees at China-Japan Friendship Hospital (Approval No: 190201).
Conflict-of-interest statement: All authors report no conflicts of interest.
Data sharing statement: Technical appendix, statistical code, and dataset available from the first author at lijuner_080629@163.com.
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: http://creativecommons.org/licenses/by-nc/4.0/
Corresponding author: Shu-Kun Yao, MD, PhD, Professor, Department of Gastroenterology, China-Japan Friendship Hospital, No. 2 Yinghua East Road, Chaoyang District, Beijing 100029, China. shukunyao@126.com
Received: August 17, 2020
Peer-review started: August 17, 2020
First decision: October 18, 2020
Revised: October 27, 2020
Accepted: November 9, 2020
Article in press: November 9, 2020
Published online: December 14, 2020
Processing time: 118 Days and 15.6 Hours
Abstract
BACKGROUND

Nonalcoholic fatty liver disease (NAFLD) has become one of the most common chronic liver diseases in the world. In our early clinical data and questionnaire analysis of NAFLD, it was found that the body mass index of some patients did not meet the diagnostic criteria for overweight or obesity. The consumption of high-temperature-processed foods such as fried food, hot pot and barbecue is closely related to the occurrence of nonobese NAFLD. Reducing the intake of this kind of food can reduce disease severity and improve prognosis.

AIM

To explore the untargeted metabolomics characteristics of nonobese nonalcoholic fatty liver disease in Sprague-Dawley rats induced by high-temperature-processed feed.

METHODS

Fifty-four male Sprague-Dawley rats were divided into three groups: The control group received a standard diet; the nonfried soybeans (NDFS) group received 60% NDFS and 40% basic feed and the dry-fried soybeans (DFS) group received 60% DFS and 40% basic feed. Six rats were sacrificed at week 4, 8, and 12 in each group. The food intake, body weight, Lee’s index, liver index, serological index and hepatic histopathology were assessed. Untargeted metabolomics characteristics were used to analyze the changes in liver metabolites of rats at week 12. Correlations between metabolites and pathology scores between the DFS and control groups and between the DFS and NDFS groups were analyzed. We selected some of the metabolites, both within the pathway and outside of the pathway, to explain preliminarily the difference in liver pathology in the three groups of rats.

RESULTS

There were no statistically significant differences in the food intake, body weight, Lee's index or serological index between the DFS group and the control group (P > 0.05). At week 8 and week 12, the steatosis scores in the DFS group were significantly higher than those in the other two groups (P < 0.05). At week 12, the liver index of the DFS group was the lowest (NDFS group vs DFS group, P < 0.05). The fibrosis score in the DFS group was significantly higher than those in the other two groups (P < 0.05). The correlation analysis of the liver pathology score and differential metabolites in the DFS and NDFS groups showed that there were 10 strongly correlated substances: Five positively correlated substances and five negatively correlated substances. The positively correlated substances included taurochenodeoxycholate-3-sulfate, acetylcarnitine, 20a,22b-dihydroxycholesterol, 13E-tetranor-16-carboxy-LTE4 and taurocholic acid. The negatively correlated substances included choline, cholesterane-3,7,12,25-tetrol-3-glucuronide, nicotinamide adenine dinucleotide phosphate, lysoPC [16:1 (9Z)] and glycerol 3-phosphate. The correlation analysis of the liver pathology score and differential metabolites in the DFS and control groups showed that there were 13 strongly correlated substances: Four positively correlated substances and 9 negatively correlated substances. The positively correlated substances included 4-hydroxy-6-eicosanone, 3-phosphoglyceric acid, 13-hydroxy-9-methoxy-10-oxo-11-octadecenoic acid and taurochenodeoxycholate-3-sulfate. The negatively correlated substances included lysoPC [16:1(9Z)], S-(9-hydroxy-PGA1)-glutathione, lysoPC [20:5 (5Z, 8Z, 11Z, 14Z, 17Z)], SM (d18:1/14:0), nicotinamide adenine dinucleotide phosphate, 5,10-methylene-THF, folinic acid, N-lactoyl-glycine and 6-hydroxy-5-methoxyindole glucuronide.

CONCLUSION

We successfully induced liver damage in rats by using a specially prepared high-temperature-processed feed and explored the untargeted metabolomics characteristics.

Keywords: Nonobese nonalcoholic fatty liver disease; High-temperature-processed feed; Mild steatosis and early fibrosis; Untargeted metabolomics characteristics; Animal models; Novel pathogenesis for nonalcoholic fatty liver disease

Core Tip: For some patients with normal body mass index and normal serum indexes, liver damage may already exist. In our previous analysis of clinical data and a high-risk factor questionnaire for patients with nonalcoholic fatty liver disease (NAFLD), we found that the body mass index of some patients did not meet the diagnostic criteria for overweight or obesity. The consumption of high-temperature-processed foods such as fried food and hot pot is closely associated with the occurrence of NAFLD. Dietary intervention to reduce the consumption of such foods can alleviate NAFLD and improve prognosis. For patients with mild liver fat changes and early fibrosis, some clinical equipment and means of diagnosis are prone to misdiagnosis. Untargeted metabolomics can preliminarily explain the difference in liver pathology in the three groups of rats.