Dietary intervention, but not losartan, completely reverses non-alcoholic steatohepatitis in obese and insulin resistant mice

Jef Verbeek, Pieter Spincemaille, Ilse Vanhorebeek, Greet Van den Berghe, Ingrid Vander Elst, Petra Windmolders, Jos van Pelt, Schalk van der Merwe, Pierre Bedossa, Frederik Nevens, Bruno Cammue, Karin Thevissen, David Cassiman

Dietary intervention is the cornerstone of non-alcoholic steatohepatitis (NASH) treatment. However, histological evidence of its efficacy is limited and its impact on hepatic pathways involved in NASH is underreported. The efficacy of the angiotensin receptor type 1 blocker losartan is controversial because of varying results in a few animal and human studies. We evaluated the effect of dietary intervention versus losartan on NASH and associated systemic metabolic features in a representative mouse model. Male C57BL/6 J mice with high fat-high sucrose diet (HF-HSD) induced NASH, obesity, insulin resistance and hypercholesterolemia were subjected to dietary intervention (switch from HF-HSD to normal chow diet (NCD)) (n = 9), continuation HF-HSD together with losartan (30 mg/kg/day) (n = 9) or continuation HF-HSD only (n = 9) for 8 weeks. 9 mice received NCD during the entire experiment (20 weeks). We assessed the systemic metabolic effects and performed a detailed hepatic histological and molecular profiling. A P-value of < 0.05, using the group with continuation of HF-HSD only as control, was considered as statistically significant. Dietary intervention normalized obesity, insulin resistance, and hypercholesterolemia (for all P < 0.001), and remarkably, completely reversed all histological features of pre-existent NASH (for all P < 0.001), including fibrosis measured by quantification of collagen proportional area (P < 0.01). At the hepatic molecular level, dietary intervention targeted fibrogenesis with a normalization of collagen type I alpha 1, transforming growth factor β1, tissue inhibitor of metalloproteinase 1 mRNA levels (for all P < 0.01), lipid metabolism with a normalization of fatty acid translocase/CD36, fatty acid transport protein 5, fatty acid synthase mRNA levels (P < 0.05) and markers related to mitochondrial function with a normalization of hepatic ATP content (P < 0.05) together with sirtuin1 and uncoupling protein 2 mRNA levels (for both P < 0.001). Dietary intervention abolished p62 accumulation (P < 0.01), suggesting a restoration of autophagic flux. Losartan did not significantly affect obesity, insulin resistance, hypercholesterolemia or any histological NASH feature. Dietary intervention, and not losartan, completely restores the metabolic phenotype in a representative mouse model with pre-existent NASH, obesity, insulin resistance and hypercholesterolemia.