Iron and copper alter tight junction permeability in human intestinal Caco-2 cells by distinct mechanisms.

摘要

Human intestinal Caco-2 cells differentiated for 15-17 days on transparent filter inserts were treated for up to 3 h with 50 and 100 &mgr;M CuCl(2) or FeSO(4) in the AP compartment at pH 6.0. Trans-epithelial electrical resistance (TEER) showed a progressive decrease during the course of the experiment that was slower in cells treated with 50 &mgr;M CuCl(2) than in those treated with 100 &mgr;M CuCl(2). Both 50 and 100 &mgr;M FeSO(4) produced a similar decrease in TEER over time, tailing off after 120 min. F-actin localization by fluorescent phalloidin binding in control cells and in cells treated for 3 h with 50 &mgr;M CuCl(2) or FeSO(4) highlighted striking differences in the two treatments. Cu(II) led to an overall reduction in F-actin staining with extensive depolymerization in areas of the monolayer, in the absence of cellular loss. Conversely, Fe(II) treatment produced disorganization of F-actin and decreased staining of the perijunctional actin filaments. No changes in the localization and intensity of staining of the junctional proteins ZO1, occludin and E-cadherin were observed after treatment with 100 &mgr;M FeSO(4) in analogy with previous observations in Cu(II)-treated cells. The data presented suggest that different mechanisms are responsible for the changes to tight junction permeability produced by the two metals.