Background & Aims: In non-alcoholic steatohepatitis (NASH) decreased nitric oxide and increased endothelin-1 (ET-1) released by sinusoidal endothelial cells (LSEC), induce hepatic stellate cells (HSC) contraction and contribute to portal hypertension (PH). Statins improve LSEC function, while ambrisentan is a selective endothelin-receptor-A antagonist. We aimed to analyse the combined effects of atorvastatin and ambrisentan on liver histopathology and hemodynamics, together with assessing the underlying mechanism in a rat NASH model.
Methods: Diet-induced NASH rats were treated with atorvastatin (10 mg/kg/day), ambrisentan (30 mg/kg/day or 2 mg/kg/day) or the combination for 2 weeks. Hemodynamic parameters were registered and liver histology and serum biochemical determinations analysed. Expression of proteins were studied by immunoblots. Conditioned media experiments were performed in LSEC. HSC were characterized by RT-PCR and a collagen lattice contraction assay was performed.
Results: Atorvastatin and ambrisentan act synergistically in combination to completely normalize liver hemodynamic and reverse histological NASH by 75%. Atorvastatin reversed the sinusoidal contractile phenotype improving endothelial function, while ambrisentan prevented the contractile response in HSC by blocking ET-1 response. Additionally, ambrisentan also increased eNOS phosphorylation levels in LSEC, via facilitating the stimulation of endothelin-receptor-B in these cells. Furthermore, the combined treated group reduced to normal serum ALT levels and showed restoration of the HSC quiescent phenotype.
Conclusions: Combination of atorvastatin and ambrisentan remarkably improves liver histology and PH in a diet-induced NASH model. By recovering LSEC function, together with inhibiting the activation and contraction of HSC, this combined treatment may be an effective treatment for patients with NASH.