The Vacuolating Autotransporter Toxin (Vat) of Escherichia coli Causes Cell Cytoskeleton Changes and Produces Non-lysosomal Vacuole Formation in Bladder Epithelial Cells

ABSTRACT Use of the nonpathogenic yeast Saccharomyces boulardiiin the treatment of infectious diarrhea has attracted growing interest. The present study designed to investigate the effect of this yeast on enteropathogenic Escherichia coli (EPEC)-associated disease demonstrates that S. boulardii abrogated the alterations induced by an EPEC strain on transepithelial resistance, [3H]inulin flux, and ZO-1 distribution in T84 cells. Moreover, EPEC-mediated apoptosis of epithelial cells was delayed in the presence of S. boulardii. The yeast did not modify the number of adherent bacteria but lowered by 50% the number of intracellular bacteria. Infection by EPEC induced tyrosine phosphorylation of several proteins in T84 cells, including p46 and p52 SHC isoforms, that was attenuated in the presence of S. boulardii. Similarly, EPEC-induced activation of the ERK1/2 mitogen-activated protein (MAP) kinase pathway was diminished in the presence of the yeast. Interestingly, inhibition of the ERK1/2 pathway with the specific inhibitor PD 98059 decreased EPEC internalization, suggesting that modulation of the ERK1/2 MAP pathway might account for the lowering of the number of intracellular bacteria observed in the presence of S. boulardii. Altogether, this study demonstrated that S. boulardii exerts a protective effect on epithelial cells after EPEC adhesion by modulating the signaling pathway induced by bacterial infection.

Download Full-text

A Pathoadaptive Deletion in an Enteroaggregative Escherichia coli Outbreak Strain Enhances Virulence in a Caenorhabditis elegans Model

Infection and Immunity ◽

10.1128/iai.00014-10 ◽

2010 ◽

Vol 78 (9) ◽

pp. 4068-4076 ◽

Cited By ~ 11

Author(s):

Jennifer Hwang ◽

Lisa M. Mattei ◽

Laura G. VanArendonk ◽

Philip M. Meneely ◽

Iruka N. Okeke

Keyword(s):

Escherichia Coli ◽

Caenorhabditis Elegans ◽

Epithelial Cells ◽

Genetic Material ◽

Decarboxylase Activity ◽

Multicopy Plasmid ◽

Lysine Decarboxylase ◽

Outbreak Strain ◽

E Coli ◽

C Elegans

ABSTRACT Enteroaggregative Escherichia coli (EAEC) strains are important diarrheal pathogens. EAEC strains are defined by their characteristic stacked-brick pattern of adherence to epithelial cells but show heterogeneous virulence and have different combinations of adhesin and toxin genes. Pathoadaptive deletions in the lysine decarboxylase (cad) genes have been noted among hypervirulent E. coli subtypes of Shigella and enterohemorrhagic E. coli. To test the hypothesis that cad deletions might account for heterogeneity in EAEC virulence, we developed a Caenorhabditis elegans pathogenesis model. Well-characterized EAEC strains were shown to colonize and kill C. elegans, and differences in virulence could be measured quantitatively. Of 49 EAEC strains screened for lysine decarboxylase activity, 3 tested negative. Most notable is isolate 101-1, which was recovered in Japan, from the largest documented EAEC outbreak. EAEC strain 101-1 was unable to decarboxylate lysine in vitro due to deletions in cadA and cadC, which, respectively, encode lysine decarboxylase and a transcriptional activator of the cadAB genes. Strain 101-1 was significantly more lethal to C. elegans than control strain OP50. Lethality was attenuated when the lysine decarboxylase defect was complemented from a multicopy plasmid and in single copy. In addition, restoring lysine decarboxylase function produced derivatives of 101-1 deficient in aggregative adherence to cultured human epithelial cells. Lysine decarboxylase inactivation is pathoadapative in an important EAEC outbreak strain, and deletion of cad genes could produce hypervirulent EAEC lineages in the future. These results suggest that loss, as well as gain, of genetic material can account for heterogeneous virulence among EAEC strains.

Download Full-text

Diffusible signal to murine alveolar macrophages from lipopolysaccharide- and Escherichia coli-stimulated lung Type II epithelial cells

Inflammation Research ◽

10.1007/s00011-004-1289-6 ◽

2004 ◽

Vol 53 (9) ◽

pp. 475-483 ◽

Cited By ~ 8

Author(s):

M. M. Farberman ◽

J. W. Hoffmann ◽

J. S. Ryerse ◽

D. E. deMello

Keyword(s):

Escherichia Coli ◽

Epithelial Cells ◽

Alveolar Macrophages ◽

Type Ii

Download Full-text

Bacterial Secretions of Nonpathogenic Escherichia coli Elicit Inflammatory Pathways: a Closer Investigation of Interkingdom Signaling

mBio ◽

10.1128/mbio.00025-15 ◽

2015 ◽

Vol 6 (2) ◽

Cited By ~ 33

Author(s):

Amin Zargar ◽

David N. Quan ◽

Karen K. Carter ◽

Min Guo ◽

Herman O. Sintim ◽

...

Keyword(s):

Escherichia Coli ◽

Epithelial Cells ◽

Negative Feedback ◽

Cell Contact ◽

Bacterial Cells ◽

Content Type ◽

Phenotypic Differences ◽

E Coli ◽

Autoinducer 2 ◽

Human Epithelial Cells

ABSTRACTThere have been many studies on the relationship between nonpathogenic bacteria and human epithelial cells; however, the bidirectional effects of the secretomes (secreted substances in which there is no direct bacterium-cell contact) have yet to be fully investigated. In this study, we use a transwell model to explore the transcriptomic effects of bacterial secretions from two different nonpathogenicEscherichia colistrains on the human colonic cell line HCT-8 using next-generation transcriptome sequencing (RNA-Seq).E. coliBL21 and W3110, while genetically very similar (99.1% homology), exhibit key phenotypic differences, including differences in their production of macromolecular structures (e.g., flagella and lipopolysaccharide) and in their secretion of metabolic byproducts (e.g., acetate) and signaling molecules (e.g., quorum-sensing autoinducer 2 [AI-2]). After analysis of differential epithelial responses to the respective secretomes, this study shows for the first time that a nonpathogenic bacterial secretome activates the NF-κB-mediated cytokine-cytokine receptor pathways while also upregulating negative-feedback components, including the NOD-like signaling pathway. Because of AI-2's relevance as a bacterium-bacterium signaling molecule and the differences in its secretion rates between these strains, we investigated its role in HCT-8 cells. We found that the expression of the inflammatory cytokine interleukin 8 (IL-8) responded to AI-2 with a pattern of rapid upregulation before subsequent downregulation after 24 h. Collectively, these data demonstrate that secreted products from nonpathogenic bacteria stimulate the transcription of immune-related biological pathways, followed by the upregulation of negative-feedback elements that may serve to temper the inflammatory response.IMPORTANCEThe symbiotic relationship between the microbiome and the host is important in the maintenance of human health. There is a growing need to further understand the nature of these relationships to aid in the development of homeostatic probiotics and also in the design of novel antimicrobial therapeutics. To our knowledge, this is the first global-transcriptome study of bacteria cocultured with human epithelial cells in a model to determine the transcriptional effects of epithelial cells in which epithelial and bacterial cells are allowed to “communicate” with each other only through diffusible small molecules and proteins. By beginning to demarcate the direct and indirect effects of bacteria on the gastrointestinal (GI) tract, two-way interkingdom communication can potentially be mediated between host and microbe.

Download Full-text

Interactions Between Salmonella Typhimurium, Enteropathogenic Escherichia Coli (EPEC), and Host Epithelial Cells

Advances in Dental Research ◽

10.1177/08959374950090010601 ◽

1995 ◽

Vol 9 (1) ◽

pp. 31-36 ◽

Cited By ~ 5

Author(s):

B.B. Finlay

Keyword(s):

Escherichia Coli ◽

Epithelial Cells ◽

Salmonella Typhimurium ◽

Host Cell ◽

Inositol Phosphate ◽

Enteric Pathogens ◽

Host Protein ◽

Host Cells ◽

Enteropathogenic Escherichia Coli ◽

Sequence Of Events

The interactions that occur between pathogenic micro-organisms and their host cells are complex and intimate. We have used two enteric pathogens, Salmonella typhimurium and enteropathogenic Escherichia coli (EPEC), to examine the interactions that occur between these organisms and epithelial cells. Although these are enteric pathogens, the knowledge and techniques developed from these systems may be applied to the study of dental pathogens. Both S. typhimurium and EPEC disrupt epithelial monolayer integrity, although by different mechanisms. Both pathogens cause loss of microvilli and re-arrangement of the underlying host cytoskeleton. Despite these similarities, both organisms send different signals into the host cell. EPEC signal transduction involves generation of intracellular calcium and inositol phosphate fluxes, and activation of host tyrosine kinases that results in tyrosine phosphorylation of a 90-kDa host protein. Bacterial mutants have been identifed that are deficient in signaling to the host. We propose a sequence of events that occur when EPEC interacts with epithelial cells. Once inside a host cell, S. typhimurium remains within a vacuole. To define some of the parameters of the intracellular environment, we constructed genetic fusions of known genes with lacZ, and used these fusions as reporter probes of the intracellular vacuolar environment. We have also begun to examine the bacterial and host cell factors necessary for S. typhimurium to multiply within epithelial cells. We found that this organism triggers the formation of novel tubular lysosomes, and these structures are linked with intracellular replication.

Download Full-text