Mucosal Immune Profiles Associated with Diarrheal Disease Severity in - and Enteropathogenic Escherichia coli-Infected Children Enrolled in the Global Enteric Multicenter Study.

Enteropathogenic Escherichia coli (EPEC) and are etiologic agents of diarrhea in children <5 years old living in resource-poor countries. Repeated bouts of infection lead to lifelong morbidity and even death. The goal of this study was to characterize local mucosal immune responses in - and EPEC-infected children <5 years of age with moderate to severe diarrhea (MSD) enrolled in the Global Enteric Multicenter Study (GEMS).

Cross-Talk between Probiotic Nissle 1917 and Human Colonic Epithelium Affects the Metabolite Composition and Demonstrates Host Antibacterial Effect.

Colonic epithelium-commensal interactions play a very important role in human health and disease development. Colonic mucus serves as an ecologic niche for a myriad of commensals and provides a physical barrier between the epithelium and luminal content, suggesting that communication between the host and microbes occurs mainly by soluble factors. However, the composition of epithelia-derived metabolites and how the commensal flora influences them is less characterized.

Phosphodiesterase 5 (PDE5) restricts intracellular cGMP accumulation during enterotoxigenic infection.

Diarrhea caused by enterotoxigenic (ETEC) has a continuing impact on residents and travelers in underdeveloped countries. Both heat-labile (LT) and heat-stable (ST) enterotoxins contribute to pathophysiology via induction of cyclic nucleotide synthesis, and previous investigations focused on intracellular signal transduction rather than possible intercellular second messenger signaling. We modeled ETEC infection in human jejunal enteroid/organoid monolayers (HEM) and evaluated cyclic nucleotide pools, finding that intracellular cAMP was significantly increased but also underwent apical export, whereas cGMP was minimally retained intracellularly and predominantly effluxed into the basolateral space.

Enterohemorrhagic (EHEC)-Secreted Serine Protease EspP Stimulates Electrogenic Ion Transport in Human Colonoid Monolayers.

One of the characteristic manifestations of Shiga-toxin-producing () infection in humans, including EHEC and O104:H4, is watery diarrhea. However, neither Shiga toxin nor numerous components of the type-3 secretion system have been found to independently elicit fluid secretion. We used the adult stem-cell-derived human colonoid monolayers (HCM) to test whether EHEC-secreted extracellular serine protease P (EspP), a member of the serine protease family broadly expressed by diarrheagenic can act as an enterotoxin.

Enteropathogenic EspH-Mediated Rho GTPase Inhibition Results in Desmosomal Perturbations.

Background & Aims: The diarrheagenic pathogen, enteropathogenic (EPEC), uses a type III secretion system to deliver effector molecules into intestinal epithelial cells (IECs). While exploring the basis for the lateral membrane separation of EPEC-infected IECs, we observed infection-induced loss of the desmosomal cadherin desmoglein-2 (DSG2). We sought to identify the molecule(s) involved in, and delineate the mechanisms and consequences of, EPEC-induced DSG2 loss.

Tandem tyrosine phosphosites in the Enteropathogenic Escherichia coli chaperone CesT are required for differential type III effector translocation and virulence.

Enteropathogenic Escherichia coli (EPEC) use a type 3 secretion system (T3SS) for injection of effectors into host cells and intestinal colonization. Here, we demonstrate that the multicargo chaperone CesT has two strictly conserved tyrosine phosphosites, Y152 and Y153 that regulate differential effector secretion in EPEC. Conservative substitution of both tyrosine residues to phenylalanine strongly attenuated EPEC type 3 effector injection into host cells, and limited Tir effector mediated intimate adherence during infection.

Phosphotyrosine-Mediated Regulation of Enterohemorrhagic Virulence.

Enteric pathogens with low infectious doses rely on the ability to orchestrate the expression of virulence and metabolism-associated genes in response to environmental cues for successful infection. Accordingly, the human pathogen enterohemorrhagic (EHEC) employs a complex multifaceted regulatory network to link the expression of type III secretion system (T3SS) components to nutrient availability. While phosphorylation of histidine and aspartate residues on two-component system response regulators is recognized as an integral part of bacterial signaling, the involvement of phosphotyrosine-mediated control is minimally explored in Gram-negative pathogens.

Enterotoxigenic Escherichia coli is phagocytosed by macrophages underlying villus-like intestinal epithelial cells: modeling ex vivo innate immune defenses of the human gut.

There is a paucity of information on diarrheagenic enterotoxigenic Escherichia coli (ETEC)'s interaction with innate immune cells, in part due to the lack of reliable models that recapitulate infection in human gut. In a recent publication, we described the development of an ex vivo enteroid-macrophage co-culture model using human primary cells. We reported that macrophages residing underneath the epithelial monolayer acquired "resident macrophage" phenotype characterized by lower production of inflammatory cytokines and strong phagocytic activity.

Genomic diversity of EPEC associated with clinical presentations of differing severity.

Enteropathogenic Escherichia coli (EPEC) are diarrhoeagenic E. coli, and are a significant cause of gastrointestinal illness among young children in developing countries. Typical EPEC are identified by the presence of the bundle-forming pilus encoded by a virulence plasmid, which has been linked to an increased severity of illness, while atypical EPEC lack this feature.

Enterohemorrhagic reduce mucus and intermicrovillar bridges in human stem cell-derived colonoids.

Background And Aims: Enterohemorrhagic (EHEC) causes over 70,000 episodes of foodborne diarrhea annually in the USA. The early sequence of events which precede life-threatening hemorrhagic colitis and hemolytic uremic syndrome are not fully understood due to the initial asymptomatic phase of the disease and the lack of a suitable animal model. The aim of this study was to determine the initial molecular events in the interaction between EHEC and human colonic epithelium.

Comparative Genomics Provides Insight into the Diversity of the Attaching and Effacing Escherichia coli Virulence Plasmids.

Attaching and effacing Escherichia coli (AEEC) strains are a genomically diverse group of diarrheagenic E. coli strains that are characterized by the presence of the locus of enterocyte effacement (LEE) genomic island, which encodes a type III secretion system that is essential to virulence. AEEC strains can be further classified as either enterohemorrhagic E.

RNA-Seq analysis of isolate- and growth phase-specific differences in the global transcriptomes of enteropathogenic Escherichia coli prototype isolates.

Enteropathogenic Escherichia coli (EPEC) are a leading cause of diarrheal illness among infants in developing countries. E. coli isolates classified as typical EPEC are identified by the presence of the locus of enterocyte effacement (LEE) and the bundle-forming pilus (BFP), and absence of the Shiga-toxin genes, while the atypical EPEC also encode LEE but do not encode BFP or Shiga-toxin.

Overview and Historical Perspectives.

In this overview, we describe the history of Shiga toxin (Stx)-producing Escherichia coli (STEC) in two phases. In phase one, between 1977 and 2011, we learned that E. coli could produce Shiga toxin and cause both hemorrhagic colitis and the hemolytic-uremic syndrome in humans and that the prototype STEC-E.

The presence of the pAA plasmid in the German O104:H4 Shiga toxin type 2a (Stx2a)-producing enteroaggregative Escherichia coli strain promotes the translocation of Stx2a across an epithelial cell monolayer.

Background: A Shiga toxin type 2a (Stx2a)-producing enteroaggregative Escherichia coli (EAEC) strain of serotype O104:H4 caused a large outbreak in 2011 in northern Europe. Pathogenic mechanisms for this strain are unclear. We hypothesized that EAEC genes encoded on the pAA virulence plasmid promoted the translocation of Stx2a across the intestinal mucosa.

H-NST induces LEE expression and the formation of attaching and effacing lesions in enterohemorrhagic Escherichia coli.

Background: Enteropathogenic E. coli (EPEC) and enterohemorrhagic E. coli are important causes of morbidity and mortality worldwide.

Serine protease EspP from enterohemorrhagic Escherichia coli is sufficient to induce shiga toxin macropinocytosis in intestinal epithelium.

Life-threatening intestinal and systemic effects of the Shiga toxins produced by enterohemorrhagic Escherichia coli (EHEC) require toxin uptake and transcytosis across intestinal epithelial cells. We have recently demonstrated that EHEC infection of intestinal epithelial cells stimulates toxin macropinocytosis, an actin-dependent endocytic pathway. Host actin rearrangement necessary for EHEC attachment to enterocytes is mediated by the type 3 secretion system which functions as a molecular syringe to translocate bacterial effector proteins directly into host cells.

The Escherichia coli phosphotyrosine proteome relates to core pathways and virulence.

While phosphotyrosine modification is an established regulatory mechanism in eukaryotes, it is less well characterized in bacteria due to low prevalence. To gain insight into the extent and biological importance of tyrosine phosphorylation in Escherichia coli, we used immunoaffinity-based phosphotyrosine peptide enrichment combined with high resolution mass spectrometry analysis to comprehensively identify tyrosine phosphorylated proteins and accurately map phosphotyrosine sites. We identified a total of 512 unique phosphotyrosine sites on 342 proteins in E.

Chromosomal and plasmid-encoded factors of Shigella flexneri induce secretogenic activity ex vivo.

Shigella flexneri is a Gram-negative, facultative intracellular pathogen that causes millions of cases of watery or bloody diarrhea annually, resulting in significant global mortality. Watery diarrhea is thought to arise in the jejunum, and subsequent bloody diarrhea occurs as a result of invasion of the colonic epithelium. Previous literature has demonstrated that Shigella encodes enterotoxins, both chromosomally and on the 220 kilobase virulence plasmid.

The ribosome binding site of a mini-ORF protects a T3SS mRNA from degradation by RNase E.

Enterohaemorrhagic Escherichia coli harbours a pathogenicity island encoding a type 3 secretion system used to translocate effector proteins into the cytosol of intestinal epithelial cells and subvert their function. The structural proteins of the translocon are encoded in a major espADB mRNA processed from a precursor. The translocon mRNA should be highly susceptible to RNase E cleavage because of its AU-rich leader region and monophosphorylated 5'-terminus, yet it manages to avoid rapid degradation.

In vivo bioluminescence imaging of Escherichia coli O104:H4 and role of aerobactin during colonization of a mouse model of infection.

Background: A major outbreak of bloody diarrhea associated with Shiga toxin-producing Escherichia coli O104:H4 occurred early in 2011, to which an unusual number of hemolytic uremic syndrome cases were linked. Due to limited information regarding pathogenesis and/or virulence properties of this particular serotype, we investigated the contribution of the aerobactin iron transport system during in vitro and in vivo conditions.

Results: A bioluminescent reporter construct was used to perform real-time monitoring of E.

Contribution of urease to colonization by Shiga toxin-producing Escherichia coli.

Shiga toxin-producing Escherichia coli (STEC) is a food-borne pathogen with a low infectious dose that colonizes the colon in humans and can cause severe clinical manifestations such as hemolytic-uremic syndrome. The urease enzyme, encoded in the STEC chromosome, has been demonstrated to act as a virulence factor in other bacterial pathogens. The NH(3) produced as urease hydrolyzes urea can aid in buffering bacteria in acidic environments as well as provide an easily assimilated source of nitrogen that bacteria can use to gain a metabolic advantage over intact microflora.

Functional and phylogenetic analysis of ureD in Shiga toxin-producing Escherichia coli.

Enterohemorrhagic Escherichia coli (EHEC) is a food-borne pathogen that can cause severe health complications and utilizes a much lower infectious dose than other E. coli pathotypes. Despite having an intact ure locus, ureDABCEFG, the majority of EHEC strains are phenotypically urease negative under tested conditions.

The LysR-type transcriptional regulator QseD alters type three secretion in enterohemorrhagic Escherichia coli and motility in K-12 Escherichia coli.

Enterohemorrhagic Escherichia coli (EHEC) O157:H7 responds to the host-produced epinephrine and norepinephrine, and bacterially produced autoinducer 3 (AI-3), through two-component systems. Further integration of multiple regulatory signaling networks, involving regulators such as the LysR-type transcriptional regulator (LTTR) QseA, promotes effective regulation of virulence factors. These include the production of flagella, a phage-encoded Shiga toxin, and genes within the locus of enterocyte effacement (LEE) responsible for attaching and effacing (AE) lesion formation.