(-)-Epicatechin prevents tumor necrosis alpha-induced permeabilization of Caco-2 intestinal monolayers

T. CONTRERAS; E. RICCIARDI; C. G. FRAGA; P. I. OTEIZA

Sietges

Congreso; V International Conference Polyphenols and Health; 2011

V International Conference Polyphenols and Health

An increased permeability of the intestinal barrier is one of the main features underlying the pathophysiology of inflammatory bowel diseases (IBD). Tumor necrosis alpha (TNFá) plays a central role in the pathogenesis of IBD, including the induction of NF-êB-dependent tight function barrier dysfunction. Food extracts enriched in (-)-epicatechin (EC) prevent the development or improve the progression of IBD in animal models. The objective of this study was to characterize the mechanisms involved in the action of EC preventing TNFá-induced permeabilization of Caco-2 monolayers. Caco-2 cells were differentiated into intestinal epithelial cells. Cells were incubated with TNFá, and with/without EC. We measured the capacity of EC to prevent TNFá-triggered cell monolayer permeabilization (measuring the transepithelial electrical resistance (TEER), and paracellular transport) and events underlying this permeabilization (oxidant production, NF-êB activation, myosin light kinase (MLCK) activation, and expression of tight junction proteins). After 24 h, TNFá caused Caco-2 cell membrane permeabilization, increasing TEER and the paracellular transport of fluorescein sulfonic acid (FSA). EC (1 µM) inhibited both events. EC (0.5-5 µM) prevented TNFá-induced cell oxidant increase and the activation of the NF-êB signaling pathway (IêBá phosphorylation, p50 and RelA nuclear transport, and nuclear NF-êB-DNA binding). TNFá caused the NF-êB-dependent upregulation of MLCK and a decrease in the expression of the tight junction protein ZO-1. Both events were prevented by EC. In conclusion, EC prevented TNFá-mediated permeabilization of Caco-2 cell monolayers. This protective effect is mediated by the capacity of EC to decrease oxidant production, and prevent NF-êB activation. Diets rich in EC could ameliorate the progression of IBD.