An improved mouse model that rapidly develops fibrosis in non‐alcoholic steatohepatitis

Abstract

Non-alcoholic steatohepatitis (NASH) is a progressive fibrotic disease, the pathogenesis of which has not been fully elucidated. One of the most common models used in NASH research is a nutritional model where NASH is induced by feeding a diet deficient in both methionine and choline. However, the dietary methionine-/choline-deficient model in mice can cause severe weight loss and liver atrophy, which are not characteristics of NASH seen in human patients. Exclusive, long-term feeding with a high-fat diet (HFD) produced fatty liver and obesity in mice, but the HFD for several months did not affect fibrosis. We aimed to establish a mouse model of NASH with fibrosis by optimizing the methionine content in the HFD. Male mice were fed a choline-deficient, L-amino acid-defined, high-fat diet (CDAHFD) consisting of 60 kcal% fat and 0.1% methionine by weight. After 1–14 weeks of being fed CDAHFD, the mice were killed. C57BL/6J mice maintained or gained weight when fed CDAHFD, while A/J mice showed a steady decline in body weight (of up to 20% of initial weight). In both strains of mice, plasma levels of alanine aminotransferase increased from week 1, when hepatic steatosis was also observed. By week 6, C57BL/6J mice had developed enlarged fatty liver with fibrosis as assessed by Masson's trichrome staining and by hydroxyproline assay. Therefore, this improved CDAHFD model may be a mouse model of rapidly progressive liver fibrosis and be potentially useful for better understanding human NASH disease and in the development of efficient therapies for this condition.

Hepatic connexin 32 associates with nonalcoholic fatty liver disease severity

“…In contrast, this group concluded that Cx32KO mice had increased liver injury and inflammation compared to WT mice. However, the WT mice fed the CDAHFD in that study developed only modest liver injury (ALT, ∼135 IU/L; AST, 49 IU/L; and histologic inflammation scores of ∼2), much lower than reported in multiple published studies showing that a CDAHFD induces severe hepatocellular injury and inflammation, as was the case in our study 24. Thus, it is unclear if the modest injury seen in the control group in their study was adequate to provide the dynamic range for appropriate comparisons between groups.…”

“…To induce NASH, 6‐8‐week‐old mice were fed a methionine‐and‐choline‐deficient diet (MCDD) for 28 days and then euthanized. Additionally, mice were fed a choline‐deficient, L‐amino acid‐defined, high‐fat diet (CDAHFD) for 9 weeks, at which time they were euthanized 24. Finally, we also used a high‐fat high‐cholesterol diet (HFHCD) for 9 weeks.…”

Molecular magnetic resonance imaging accurately measures the antifibrotic effect of EDP‐305, a novel farnesoid X receptor agonist

“…The CDAHFD model produces rapid and severe lipotoxic hepatic injury by preventing very low‐density lipoprotein production and hepatocyte lipid transport 25. As evidenced by the natural history experiment, the capacity to store lipid is a marker of retained hepatocyte function that dissipates shortly after 6 weeks of diet.…”

“…However, this model requires multiple months to develop evidence of hepatic fibrosis, which remains mild to moderate in severity throughout the course of disease. The CDAHFD lacks the metabolic derangements observed in NASH, but the choline deficiency provides a severe lipotoxic hepatic injury and robust fibrotic response 25. We therefore chose to use a choline‐deficiency model despite the acknowledged metabolic limitations.…”

“…Control animals (n = 6) underwent a sham procedure. Male C57BL/6 mice (n = 24) were fed a CDAHFD consisting of 60% kcal fat and 0.1% methionine 25. Control animals (n = 4) were fed normal chow.…”