P0938 : Olive oil comsumption ameliorates non-alcoholic steatohepatitis induced by hypercaloric and hyperlipidic western diets

Abstract

Background and Aims: Activation of hepatic stellate cells (HSC) and dysregulation of several mediators such as matrix metalloproteinases (MMPs) and their inhibitors (TIMPs) play a determinant role in the fibrogenesis during the progression of NAFLD to NASH. This study was aimed to establish the interplay between hepatocytes and HSC in an in vitro cell model of NASH. Methods: The effect of free fatty acids (FFA) (Oleic:Palmitic, 2:1) was analyzed at short (24h) and long (96h) exposure times in different experimental set-ups: (1) Monoculture of each cell type; (2) Transwell system (soluble mediators effects) and (3) simultaneous co-culture (SCC) by seeding both cell types together (cell-to-cell interaction). In each system was assessed the amount of steatosis; expression of HSC activation marker (a-SMA), ECM turnover regulators (MMP-2 and TIMP-2) as well as collagen biosynthesis in comparison to untreated cells (ctrl). Results: The amount of steatosis was comparable among all the experimental set-ups. However, HSC activation in terms of a-SMA gene (2.20±0.25-folds; p < 0.01) and protein (1.70±0.20folds; p < 0.01) expression was only increased in the SCC and was maximal after 24h of FFA exposure. Similarly, the close contact of the two cell types induced an up-regulation of TIMP2 protein (1.42±0.27-folds; p < 0.05) which was inversely correlated both with MMP-2 protein (0.58±0.10-folds; p < 0.01) and activity (0.70±0.13folds; p < 0.05). This dysregulation was accompanied by an increase of collagen biosynthesis at longer FFA exposure times (1.5±0.10folds, p < 0.01). Any of these effects was directly induced by FFA (monoculture) nor by the soluble mediators (transwell). Conclusions: Our data suggest that hepatocytes-to-HSC proximity/interaction is essential for fibrosis initiation in NASH.