Two stages of enteropathogenic Escherichia coli intestinal pathogenicity are up and down-regulated by the epithelial cell differentiation

Abstract

Pathogens and eucaryotic cells are active partners during the process of pathogenicity. To gain access to enterocytes and to cross the epithelial membrane, many enterovirulent microorganisms interact with the brush border membrane-associated components as receptors. Recent reports provide evidence that intestinal cell differentiation plays a role in microbial pathogenesis. Human enteropathogenic Escherichia coli (EPEC) develop their pathogenicity upon infecting enterocytes. To determine if intestinal epithelial cell differentiation influences EPEC pathogenicity, we examined the infection of human intestinal epithelial cells by JPN 15 (pMAR7) [EAF+ eae+] EPEC strain as a function of the cell differentiation. The human embryonic intestinal INT407 cells, the human colonic T84 cells, the human undifferentiated HT-29 cells (HT-29 Std) and two enterocytic cell lines, HT-29 glc-/+ and Caco-2 cells, were used as cellular models. Cells were infected apically with the EPEC strain and the cell-association and cell-entry were examined by quantitative determination using metabolically radiolabeled bacteria, as well as by light, scanning and transmission electron microscopy. [EAF+ eae+] EPEC bacteria efficiently colonized the cultured human intestinal cells. Diffuse bacterial adhesion occurred to undifferentiated HT-29 Std and INT407 cells, whereas characteristic EPEC cell clusters were observed on fully differentiated enterocytic HT-29 glc-/+ cells and on colonic crypt T84 cells. As shown using the Caco-2 cell line, which spontaneously differentiates in culture, the formation of EPEC clusters increased as a function of the epithelial cell differentiation. In contrast, efficient cell-entry of [EAF+ eae+] EPEC bacteria occurred in recently differentiated Caco-2 cells and decreased when the cells were fully differentiated.(ABSTRACT TRUNCATED AT 250 WORDS)

Two Atypical Enteropathogenic Escherichia coli Strains Induce the Production of Secreted and Membrane-Bound Mucins To Benefit Their Own Growth at the Apical Surface of Human Mucin-Secreting Intestinal HT29-MTX Cells

“…It has been demonstrated that one aEPEC strain expressing the intimin subtype omicron was more invasive than tEPEC in undifferentiated, nonintestinal HeLa and Hep-2 cells (30). Consistent with what was previously reported for tEPEC (18), aEPEC strains were invasive in undifferentiated human intestinal Caco-2 cells and weakly invasive in differentiated enterocyte-like cells (66). Intriguingly, the aEPEC 0621-6, 1632-7, and 1871-1 strains showed a significant invasiveness capacity in the differentiated cryptic-like T84 cells in contrast with the typical tEPEC E2348/69 strain (77).…”

Polarized Entry of Uropathogenic Afa/Dr Diffusely AdheringEscherichia coliStrain IH11128 into Human Epithelial Cells: Evidence for α5β1Integrin Recognition and Subsequent Internalization through a Pathway Involving Caveolae and Dynamic Unstable Microtubules

“…Internalization of E. coli was measured by quantitative determination of bacteria located within the infected cell monolayers by using the aminoglycoside antibiotic assay (13,22). The concentration of gentamicin that reduced the bacterial count by 99.99% was determined in a preliminary experiment.…”

“…In contrast, an efficiently invasive E. coli strain isolated from a patient with Crohn's disease showed several differences in the mechanism of cell entry from that of EIEC (8). Cell entry at low levels of invasion by enterotoxinogenic E. coli (19), enterohemorrhagic E. coli (50), enteroaggregative E. coli (4), enteropathogenic E. coli (22), and Afa/Dr diffusely adhering E. coli (DAEC) (25,26,35,63) has been reported.…”

Virulence of EnteropathogenicEscherichia coli, a Global Pathogen

“…Thus, when EPEC bacteria that were nonadherent after 60 min of incubation with cultured HEp-2 cells were subsequently transferred to uninfected HEp-2 cells, LA occurred within 15 min compared with 30 to 60 min for noninduced bacteria. Interestingly, EPEC adherence experiments using the enterocyte-like HT-29 cell line suggested that LA of the bacteria occurred only when the HT-29 cells were differentiated, suggesting that LA requires an unknown host cell receptor that is expressed only after differentiation (64).…”

“…AE lesion formation is dependent on a number of physiological and environmental conditions (146) and is optimal in early to midlogarithmic growth at 37°C (AE lesions are not induced at 28°C). Infection with enterohemorrhagic E. coli (EHEC) results in the formation of similar lesions at the point of bacterial contact; however, these lesions are different in composition (38,64) and are localized to the terminal ileum or colon (82). The mouse pathogen Citrobacter freundii is also able to stimulate the production of AE lesions in vitro (5,154).…”