Differences in metabolic and liver pathobiology induced by two dietary mouse models of nonalcoholic fatty liver disease

Abstract

Non-alcoholic fatty liver disease (NAFLD) is a growing epidemic linked to metabolic disease. The first stage of NAFLD is characterized by lipid accumulation in hepatocytes, but this can progress into non-alcoholic steatohepatitis (NASH), cirrhosis, and hepatocellular carcinoma (HCC). Western diets, high in fats, sugars and cholesterol are linked to NAFLD development. Murine models are often used to study NAFLD; however, there remains debate on which diet-induced model best mimics both human disease progression and pathogenesis. In this study, we performed a side-by-side comparison of two popular diet models of murine NAFLD/NASH and associated HCC: a high fat diet supplemented with 30% fructose water (HFHF) and a western diet high in cholesterol (WDHC), comparing them to a common grain-based chow diet (GBD). Mice on both experimental diets developed liver steatosis, while WDHC-fed mice had greater levels of hepatic inflammation and fibrosis than HFHF-fed mice. In contrast, HFHF-fed mice were more obese and developed more severe metabolic syndrome, with less pronounced liver disease. Despite these differences, WDHC-fed and HFHF-fed mice had similar tumour burdens in a model of diet-potentiated liver cancer. Response to diet and resulting phenotypes were generally similar between sexes, albeit delayed in females. This study shows that modest differences in diet can significantly uncouple glucose homeostasis and liver damage. In conclusion, long-term feeding of either HFHF or WDHC are reliable methods to induce NASH and diet-potentiated liver cancer in mice of both sexes; however, the choice of diet involves a trade-off between severity of metabolic syndrome and liver damage.

Diet-Induced Models of Non-Alcoholic Fatty Liver Disease: Food for Thought on Sugar, Fat, and Cholesterol

“…Impacts of 0.75% dietary cholesterol on hepatic inflammation and fibrosis are markedly increased when combined with poly-unsaturated fatty acids (PUFA), like ω6-PUFA from soybean oil [ 42 , 53 ], whereas this amount of added cholesterol also causes more severe steatosis, weight gain, and insulin resistance [ 43 ]. In comparison, we show that mice fed a high-fat/high-fructose diet supplemented with 2% cholesterol (40% kcal fat) have increased inflammation and fibrosis in liver, while obesity, insulin resistance and glucose intolerance are less pronounced compared to mice fed a similar diet without cholesterol [ 55 ]. Consistently, mice fed obesogenic diets with higher cholesterol levels, such as 1.25% and 2%, seem to exhibit similar impairments in weight gain [ 55 , 56 , 57 ].…”

“…In comparison, we show that mice fed a high-fat/high-fructose diet supplemented with 2% cholesterol (40% kcal fat) have increased inflammation and fibrosis in liver, while obesity, insulin resistance and glucose intolerance are less pronounced compared to mice fed a similar diet without cholesterol [ 55 ]. Consistently, mice fed obesogenic diets with higher cholesterol levels, such as 1.25% and 2%, seem to exhibit similar impairments in weight gain [ 55 , 56 , 57 ]. Thus, too much cholesterol may counteract the goal of modeling liver damage within a setting of obesity and insulin resistance.…”

“…In contrast, work from our research group shows that a common grain-based chow diet (24% kcal protein, 58% kcal carbohydrates and 18% kcal fat) can surprisingly promote weight gain and hepatic steatosis similar to a high-fat/high-fructose diet (20% kcal protein, 35% kcal carbohydrates, 45% kcal fat, supplemented with 30% fructose water) when mice are fed over long periods of time (8 months) [ 55 ]. Because the standard chow diet is obesogenic on its own, the metabolic effects of the high-fat/high-fructose diets are significantly masked [ 55 ]. Accumulating literature provides evidence that many standard lab chow formulations are not “healthy” and can change ingredient sources batch-to-batch.…”

Non-alcoholic Steatohepatitis Pathogenesis, Diagnosis, and Treatment

“…Consumption of a high-calorie diet with high fat and high sugar (western diet) results in weight gain and is the initial event for the development of fatty liver (125)(126)(127). Particular types of lipids and carbohydrates play important roles in the progression of NASH.…”

Considerations When Choosing High-Fat, High-Fructose, and High-Cholesterol Diets to Induce Experimental Nonalcoholic Fatty Liver Disease in Laboratory Animal Models

“…After an additional 12 wk on this diet, histological analysis (based on hematoxylin and eosin staining) and a mean NAS score (± SE) of 6.2 ± 0.4 indicated that this modified diet induced histologic features characteristic of NASH with fibrosis (mean score ± SE: 1.40 ± 0.16), including micro- and macrovesicular steatosis, hepatocyte ballooning, and infiltration of inflammatory cells ( 30 ). In another study, the same diet was fed to both male and female C57BL/6N mice, and after 31 wk all mice had increased liver damage (hepatocyte ballooning, lobular inflammation) and fibrosis (F3–F4 for ≥50% of mice), but only mild weight gain and insulin resistance ( 31 ). Female mice were slightly slower to respond to the diet intervention, with normal concentrations of circulating ALT at week 12, but significantly elevated by week 24.…”