Enteropathogenic Escherichia coli adherence to intestinal epithelial monolayers diminishes barrier function

Abstract

The mechanism by which enteropathogenic Escherichia coli (EPEC) causes diarrhea remains elusive. Several alterations within the host cell have been demonstrated to occur following EPEC attachment including increases in intracellular Ca2+ concentration and rearrangement and phosphorylation of several cytoskeletal proteins. The consequences of these intracellular perturbations on host cell function, however, have not been determined. The aim of this study was to examine the effect of EPEC adherence on intestinal epithelial barrier function. T84 cell monolayers were infected with either wild-type EPEC or a nonadherent isogenic derivative. Transepithelial electrical resistance, a measure of barrier function, decreased 33.5 +/- 6.4% after a 6-h incubation with the wild-type strain. Electron microscopy revealed ultrastructurally normal cells, and lactate dehydrogenase release assays failed to demonstrate cytotoxicity. Dual 22Na+ and [3H]mannitol flux studies localized the permeability defect to tight junctions. In addition, cumulative flux of the paracellular marker mannitol was four- to fivefold greater across monolayers infected with wild-type EPEC. Sequestration of intracellular calcium stores by dantrolene completely abrogated the resistance drop associated with EPEC attachment. These data demonstrate that adherence of EPEC to intestinal epithelial cell monolayers disrupts tight junction barrier function via a calcium-requiring event.

Enteropathogenic Escherichia coli dephosphorylates and dissociates occludin from intestinal epithelial tight junctions

“…We have shown previously that EPEC alters the tight junction barrier function of the host intestinal epithelial tissues (Spitz et al, 1995). Additional studies from our laboratory have demonstrated that one mechanism by which EPEC enhances paracellular permeability is by phosphorylating MLC 20 (Yuhan et al, 1997).…”

“…We are far from understanding the regulation of each of these molecules and the interactions that very likely exist between them. It is becoming increasingly clear that tight junctions are altered by both physiological (Madara and Pappenheimer, 1987;Turner et al, 1997) and pathophysiological processes (Spitz et al, 1995;Yuhan et al, 1997;Philpott et al, 1998;Sonoda et al, 1999). Here, we examine the impact of an important and interesting enteric bacterial pathogen, enteropathogenic Escherichia coli, on the tight junction-associated, transmembrane protein occludin.…”

“…n 6 for each group; P 0.3 for control 1 gentamicin vs. EPEC 1 gentamicin. (Spitz et al, 1995;Yuhan et al, 1997). We therefore questioned whether the EPEC-induced decrease in transepithelial electrical resistance was also reversible, providing a function correlation for the demonstrated morphological and biochemical reversibility of alteration in occludin.…”

“…The EPEC strain E2348/69 used in these studies is a wildtype strain that demonstrates localized adherence to T 84 cells (Spitz et al, 1995). UMD864 harbours a deletion of the espB gene, whose product, EspB, is essential for the activation of signal transduction (Foubister et al, 1994).…”

Enteropathogenic Escherichia coli infection leads to appearance of aberrant tight junctions strands in the lateral membrane of intestinal epithelial cells

“…Enteropathogenic E. coli (EPEC), a diarrhoeagenic pathogen of importance in developing countries (Nataro and Kaper, 1998), has been shown to alter the tight junction barrier function of the host intestinal epithelial tissues (Spitz et al ., 1995). Intimate attachment of EPEC to host intestinal epithelial cells is the result of interaction between a bacterial outer membrane protein intimin and the translocated intimin receptor (Tir) that is injected into the host cell by a type III secretion system Deibel et al ., 1998).…”