White-wine pomace products prevent clinic Listeria virulence through modulation of adherens and tight junction in intestinal cells

Abstract

In recent years the use of functional ingredients and its bioactive components as regulators for the microbiota and as antioxidants has risen. Our research group has worked for years with sub-products of the wine industry, analyzing their effects in pathologies related to oxidative stress. The aim of this study was to see the effect of white-wine pomace bioavailable products in the prevention of clinic Listeria virulence on intestinal cells, and the molecular pathways activated. The white-wine pomace composition was analyzed, focusing mainly on the polyphenols and fiber content, which are mainly responsible for its antioxidant capacity and bioactive products. The bioavailable fractions were obtained by gastrointestinal digestion and colonic fermentation of the white-wine pomace products (WPP) and were characterized, focusing again in the phenolic metabolites and short-chain fatty acids. The bioavailability in vitro of the fractions was tested in intestinal cells Caco-2 using a Transwell assay. The integrity of the layer was analyzed with an EVOM2 equip, controlling the values of the trans-epithelial electric resistance. The effect of the digested fractions on the cell viability has been evaluated by MTT method and not viability changes were observed with bioavailable fractions. The preventive effect on clinic Listeria monocytogenes virulence was evaluated in a Caco-2 cell intestinal line. The cells were cultured in presence of gastrointestinal or fermented fractions by 24 hours and then were infected with different strains of Listeria by one hour. A reduction in the virulence of several strains of Listeria was documented when the cells had been pre-treat- ed with either of the fractions, compared with the ones that had not. The last step was to determine which pathways were modulated in Caco-2 to reduce the virulence. It has been shown that L. monocytogenes induces endothelial barrier dysfunction via the redistribution of junctional proteins. The expression of several adherens junctional proteins was analyzed via qPCR after the RNA was extracted from cells treated and infected in the same conditions as discussed before.