Abstract
Objectives
To develop a mouse model of non-alcoholic fatty liver disease (NAFLD) that replicates the characteristic of the disease in humans, including development of obesity, dysbiosis, fibrosis and liver tumors.
Methods
Agouti yellow (Ay) mice, which have hyperphagia, were fed a Western diet (WD) (42% kcal from fat, 341 g/Kg sucrose, and 0.2% cholesterol) and a drinking solution containing fructose and glucose equivalent to 42 g/L of high fructose corn syrup (HFCS). Wild-type mice fed a low-fat diet (LFD) (10% kcal from fat) served as lean controls. After 16 weeks of diet treatment, tissues were collected and analyzed. Obesity was evaluated via body weight and body composition. NAFLD was evaluated by histology and confirmed by liver lipid quantification, plasma ALT and AST levels, expression of inflammation-related genes, and fibrosis-specific staining. Gene expression profile was evaluated by RNAseq. Gut microbiota dysbiosis was evaluated by 16S rRNA metagenomics.
Results
Ay mice fed the Western diet and HFCS for 16 weeks developed obesity and NAFLD. Histological evaluation determined that the mice developed non-alcoholic steatohepatitis (NASH) with steatosis, liver injury, inflammation, and fibrosis. This was confirmed by the following analyses: In these mice, steatosis, quantified by liver TAG content, increased 4X when compared to lean controls. Liver injury, assessed by measuring plasma ALT and AST, increased 11X and 4X, respectively. Inflammation, evaluated by liver mRNA expression of Tnf and CCl2, increased 6X and 12X, respectively. Fibrosis, quantified morphometrically, increased 2.5X. Gene expression profiling showed increases in inflammation- and fibrosis-related pathways, similar to NASH in humans. In addition, these mice developed gut microbiota dysbiosis, with increased Bacteroidetes and Proteobacteria and decreased Firmicutes, as reported in NASH in humans. Finally, 60% of the Ay mice developed liver tumors when fed the WD + HFCS diet for one year.
Conclusions
Ay mice fed a Western diet and HFCS developed obesity, gut microbiota dysbiosis, and NASH, including fibrosis and tumors, replicating the characteristics of NASH in humans. We present this as a new model for studying NASH physiopathology and testing new therapies.
Funding Sources
NIH CUNY.
Dietary switch to western diet induces hypothalamic adaptation associated with gut microbiota dysbiosis in rats
