Figure 1.

Trans-epithelial electrical resistance of Caco-2/HT29-MTX monolayers. Effect of macrophage-conditioned medium. After a tight monolayer had formed, (+)-catechin (CAT) and procyanidin B₂ (PB₂) (50 µM) were added, where indicated, to the apical chamber (T0). After 24 h, the medium in the basolateral chamber was replaced by conditioned medium of Raw264.7 macrophages stimulated by LPS (conditioned medium of activated macrophages (MCM), see Methods) and the incubation prolonged for further 72 h. Trans-epithelial electrical resistance (TEER) was determined, as described under Methods, at the indicated times and expressed as changes relative to control cells, calculated according to Equation 1 (see Methods). Control cells were monolayers treated with conditioned medium obtained from Raw264.7 cultures not activated by LPS (see Methods). Data are means ± SD of 3 independent determinations. *** p < 0.001 vs. control cultures; #, ##, ### p < 0.05, 0.01, 0.001 vs. monolayers treated with CAT and PB₂ but not with MCM. The experiment was performed twice with comparable results.