Enteropathogenic Escherichia coli decreases the transepithelial electrical resistance of polarized epithelial monolayers

Abstract

The mechanisms whereby enteropathogenic Escherichia coli (EPEC) causes diarrhea remain undefined. We found that EPEC caused a decrease in transepithelial electrical resistance across polarized monolayers of Caco-2 and MDCK epithelial cells. This occurred approximately 6 to 10 h after bacterial addition .and was reversible if the monolayers were treated with tetracycline or gentamicin. Although significant alterations in host actin occurred beneath adherent EPEC, actin filaments supporting tight junctions were not noticeably affected in the epithelial cells, nor was the distribution of ZO-1, a tight junction protein. Despite the decrease in transepithelial electrical resistance, EPEC did not cause an increase in [3H]inulin penetration across MDCK monolayers. Unlike in the parental strain, mutations in any loci involved in adherence or formation of attaching and effacing lesions were unable to cause a decrease in transepithelial resistance. These data indicate that EPEC causes a decrease in transepithelial electrical resistance by disrupting a transcellular (intracellular) pathway rather than by disrupting intercellular tight junctions (paracellular) and that these disruptions occur only when attaching and effacing lesions are formed.Enteropathogenic Escherichia coli (EPEC) is a leading cause of infantile diarrhea in developing nations (17,24). Despite its prevalence, EPEC virulence factors involved in diarrhea are not well understood. Unlike enterotoxigenic E. coli, no toxin secretion is associated with EPEC pathogenicity (27). Instead, EPEC pathogenicity involves interactions of the bacteria with its target epithelial cells to cause attaching and effacing (A/E) lesions.

Modulation of tight junction barrier function by outer membrane proteins of enteropathogenic Escherichia coli: Role of F‐actin and junctional adhesion molecule‐1

“…This finding is consistent with previous report that espB mutant and the EAF mutant bacteria and their OMPs were deficient in causing increase in permeability and dissociation of b-catenins (Malladi et al, 2004b). Both these mutants are deficient in signal transduction and mutants partially or totally deficient in adherence or signal transduction lose the ability to disrupt barrier function (Canil et al, 1993;Philpott et al, 1996).…”

“…A potential TJ effect has most often been documented by a reduction in transepithelial electrical resistance (TER). EPEC infection has shown to decrease TER (Canil et al, 1993;Philpott et al, 1996). One of the LEE-encoded proteins, EspF is required for EPEC induced loss of TER (McNamara et al, 2001).…”

Novel effects of the prototype translocating Escherichia coli, strain C25 on intestinal epithelial structure and barrier function

“…Some experiments were conducted using confluent monolayers (2.0 ¥ 10 5 cm -2 ) of MDCK-I cells, kindly provided by Roger Worrell (The Vontz Center for Molecular Studies, University of Cincinnati, Cincinnati, OH) (Lipschutz et al, 2005). These cells form polarized monolayers with consistently high TER in culture and have been used to determine alterations in barrier function induced by enteric bacteria (Canil et al, 1993). The cells were maintained in DMEM supplemented with 10% (v/v) fetal bovine serum, and 2% (v/v) penicillin-streptomycin (Gibco).…”

The bacterial effectors EspG and EspG2 induce a destructive calpain activity that is kept in check by the co-delivered Tir effector

“…It has long been established that EPEC can disrupt epithelial barrier function (Canil et al, 1993) -an essential feature of the intestinal epithelium that is maintained through apically located TJs between adjacent cells (Schneeberger and Lynch, 2004). TJs create an effective barrier to the movement of small molecules across the epithelium and this can be measured as trans-epithelial electrical resistance (TER).…”