Animal models for analyzing metabolic syndrome-associated liver diseases.

Metabolic syndrome (MS) is a worldwide healthcare issue and a dominant risk factor for the development of incurable diseases affecting the entire body. The hepatic manifestations of MS include nonalcoholic fatty liver disease (NAFLD) and its progressive variant, nonalcoholic steatohepatitis (NASH). NASH is known to progress to liver cirrhosis and hepatocellular carcinoma (HCC). Excellent animal models for determining the mechanism of pathogenesis and establishing therapeutic treatment of NASH/HCC are strongly required worldwide. We recently reported that two previously established mouse models of obesity and diabetes mellitus, namely, Tsumura-Suzuki Obese Diabetes (TSOD) mice and MSG mice, developed MS-associated NASH and that their clinical course and pathological characteristics closely mimicked those of human MS-NASH patients. Interestingly, most of the mice developed HCC with advancing age, and the pathological and functional characteristics of this condition were identical to those of human HCC. We further established a novel mouse model of HCC based on type 1 diabetes (DIAR-nSTZ mice) and reported its histopathological features. By comparing various aspects of these mouse models, specific and useful characteristics in a suitable model of MS-associated liver diseases, including hepato-carcinogenesis, can be highlighted.