Comparative study of liver injury induced by high-fat methionine- and choline-deficient diet in ICR mice originating from three different sources

Lee et al. Laboratory Animal Research (2019) 35:15 https://doi.org/10.1186/s42826-019-0016-y Laboratory Animal Research RESEARCH Open Access Comparative study of liver injury induced by high-fat methionine- and cholinedeficient diet in ICR mice originating from three different sources Seunghyun Lee1†, Jae-Hwan Kwak2†, Sou Hyun Kim1, Tae Bin Jeong1, Seung Won Son1, Joung-Hee Kim1, Yong Lim3, Joon-Yong Cho4, Dae Youn Hwang5, Kil Soo Kim6 and Young-Suk Jung1* Abstract Non-alcoholic fatty liver disease (NAFLD) is the leading cause of chronic liver disease worldwide. It is characterized by the accumulation of lipids without alcohol intake and often progresses to non-alcoholic steatohepatitis (NASH), liver fibrosis, and end-stage liver diseases such as cirrhosis or cancer. Although animal models have greatly contributed to the understanding of NAFLD, studies on the disease progression in humans are still limited. In this study, we used the recently reported high-fat L-methionine-defined and choline-deficient (HFMCD) diet to rapidly induce NASH and compared the responses to HFMCD in ICR mice from three different countries: Korea (supplied by the National Institute of Food and Drug Safety Evaluation), USA, and Japan during 6 weeks. Feeding HFMCD did not cause significant differences in weight gain in comparison with mice fed control diet. Relative weight of the liver increased gradually, while the relative weight of the kidneys remained unchanged. The parameters of liver injury (serum activities of alanine aminotransferase, aspartate aminotransferase, and lactate dehydrogenase) increased rapidly from 1 week and remained elevated for as long as 6 weeks. Histopathological analysis showed that the accumulation of hepatic lipids induced by HFMCD was prominent at 1 week after diet supplementation and increased further at 6 weeks. Inflammatory markers were significantly increased in a time-dependent manner by HFMCD. The mRNA levels of TNF-α and IL-6 were elevated approximately 15-fold relative to control diet and that of IL-1β was increased more than 20-folds at 6 week after the onset of HFMCD intake. In addition, mRNA expression of fibrosis markers such as α-SMA, TGFβ1, and Col1a1 were also significantly increased at 6 week. In summary, the responses of Korl:ICR mice by intake of HFMCD diet were similar to those of ICR mice from other sources, which suggests that Korl:ICR mice is also a useful resource to study the pathogenesis of diet-induced NAFLD. Keywords: Non-alcoholic fatty liver disease, Liver injury, High-fat L-methionine- and choline-deficient diet, ICR mouse Introduction Non-alcoholic fatty liver disease (NAFLD) is a liver metabolic disorder that does not involve alcohol intake. Importantly, over the years obesity rates have increased due to changes in lifestyle and food habits, and as a result NAFLD has become a common cause of chronic liver disease in many countries [1]. NAFLD includes a wide spectrum of liver diseases from simple steatosis to non* Correspondence: † Seunghyun Lee and Jae-Hwan Kwak contributed equally to this work. 1 College of Pharmacy, Pusan National University, Busan, South Korea Full list of author information is available at the end of the article alcoholic steatohepatitis (NASH), fibrosis and cirrhosis, and ultimately hepatocellular carcinoma and liver failure [2]. Simple steatosis is usually not considered a serious condition. However, NASH can develop into cirrhosis or liver cancer, which may eventually be fatal [3]. Although many studies have been carried out, the pathological mechanisms of NAFLD remain to be elucidated and therapeutic drugs remain to be developed. The wide spectrum of NAFLDs makes it difficult to identify precise stage of disease, and the characteristics of very slowly progressive diseases are difficult to determine in clinical research [4]. Therefore, an animal model recapitulating © The Author(s). 2019 Open Access This article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated. Lee et al. Laboratory Animal Research (2019) 35:15 human NAFLD can provide important information to determine the pathogenesis of the disease and to investigate the therapeutic effects of various drugs [5]. Animal models of NAFLD are largely classified as genetically engineered and nutritional (dietary) models according to etiology. In general, dietary induction of NAFLD in experimental animals is the preferred method to reproduce conditions observed in humans such as metabolic syndrome, whereas genetically engineered animals are used for detailed mechanistic studies [6]. Because the ICR mice have a low level of aggression and strong breeding ability, they are used worldwide for research on many diseases in diverse fields such as oncology, infections, and pharmacology [7]. The most widely used diet to induce NAFLD is the methionine- and choline-deficient (MCD) diet. It provides a very reproducible and efficient model to induce a severe NASH phenotype in a short period of administration such as 8 weeks [8]. Specifically, choline deficiency inhibits the synthesis of phosphatidylcholine, which is required for very low-density lipoprotein (VLDL) production, and is followed by lipid accumulation in the liver [9, 10]. The deficiency of the essential amino acid methionine decreases the biosynthesis of glutathione (GSH), the most potent antioxidant in the body, and leads to oxidative stress, which in turn contributes to liver damage [11]. However, MCD diet can cause serious weight loss, which is not usually observed in patients with NAFLD [12, 13]. Another well-studied dietary model is high-fat diet–induced NAFLD accompanied by obesity, although the diverse composition of such diets makes it difficult to compare studies from different research groups. Standard high-fat diets generally result in hepatic steatosis and do not induce significant NASH symptoms such as cell death, inflammation, or fibrosis even after feeding for more than 28 weeks [14]. A recent study introduced an improved mouse model to overcome the limitations of both MCD and high-fat diet [6]. The authors developed high-fat L-methionine- and choline-deficient (HFMCD) diet, composed of 60 kcal% fat, no added choline, and 0.1% methionine, by combining MCD with high-fat diet. This diet rapidly induced Page 2 of 7 inflammatory response and fibrosis as well as steatosis in C57BL/6 J mice within 6 weeks without weight loss [6]. The Korl:ICR mice, which is the resident stock of the Nati (...truncated)