A novel in vitro model of alcohol-induced hepatic fibrogenesis

Chronic alcohol consumption is one of the main etiological factors for liver disease worldwide, however, only a fraction of drinkers develops significant hepatic inflammation, and even less progresses to significant hepatic fibrosis and cirrhosis. Still, there are no experimental models that lead to relevant hepatic fibrosis, and there is a high need to unravel the mechanisms and factors promoting hepatic injury in alcoholic liver disease (ALD).The aim of this study was to establish an in vitro model to study the hepatocyte mediated effects of alcohol on hepatic stellate cells (HSCs), the central mediators of liver fibrogenesis. Methods and Results: HepG2 hepatoma cells and primary human hepatocytes (PHH) were incubated with different concentrations of alcohol (0.1–1%) for 48h, which did not affect cell viability or mitochondrial activity but led to dose-dependent hepatocellular lipid accumulation as assessed by analysis of triglyceride content and free fatty acid levels, and as visualized by oil red o staining. Subsequently, human HSC were incubated with conditioned media (CM) from alcohol stimulated (Alc) or control hepatocytes. Further controls included control medium with and without alcohol (at concentrations determined in the CM from Alc-treated cells). Noteworthy, incubation of HSC with CM from Alc-treated hepatocytes significantly induced proliferation as well as pro-fibrogenic (TGF-beta) and NFkapaB-mediated pro-inflammatory gene (IL-8, RANTES) expression compared to the control groups. Conclusion: Our in vitro data indicate release of soluble factors as a potential mechanism for development and progression of fibrogenesis in alcoholic liver disease, the identification of which may lead to novel prognostic markers. Thus, this study provides an attractive in vitro model to study molecular mechanisms of alcohol-induced fibrogenesis, and to identify and test novel targets for anti-fibrotic therapies in alcoholic liver disease.