Browse
Submit Data
Databases
API
Help

Dataset Information

21 Views

0 Connections

0 Citations

0 Reanalyses

0 Downloads

Omics score: 0

TLR4 Participates in the Inflammatory Response Induced by the AAF/II Fimbriae From Enteroaggregative Escherichia coli on Intestinal Epithelial Cells.

ABSTRACT: Enteroaggregative Escherichia coli (EAEC) infections are one of the most frequent causes of persistent diarrhea in children, immunocompromised patients and travelers worldwide. The most prominent colonization factors of EAEC are aggregative adherence fimbriae (AAF). EAEC prototypical strain 042 harbors the AAF/II fimbriae variant, which mediates adhesion to intestinal epithelial cells and participates in the induction of an inflammatory response against this pathogen. However, the mechanism and the cell receptors implicated in eliciting this response have not been fully characterized. Since previous reports have shown that TLR4 recognize fimbriae from different pathogens, we evaluated the role of this receptor in the response elicited against EAEC by intestinal cells. Using a mutual antagonist against TLR2 and TLR4 (OxPAPC), we observed that blocking of these receptors significantly reduces the secretion of the inflammatory marker IL-8 in response to EAEC and AAF/II fimbrial extract in HT-29 cells. Using a TLR4-specific antagonist (TAK-242), we observed that the secretion of this cytokine was significantly reduced in HT-29 cells infected with EAEC or incubated with AAF/II fimbrial extract. We evaluated the participation of AAF/II fimbriae in the TLR4-mediated secretion of 38 cytokines, chemokines, and growth factors involved in inflammation. A reduction in the secretion of IL-8, GRO, and IL-4 was observed. Our results suggest that TLR4 participates in the secretion of several inflammation biomarkers in response to AAF/II fimbriae.

SUBMITTER: Alvestegui A

PROVIDER: S-EPMC6509964 | biostudies-literature |

REPOSITORIES: biostudies-literature

ACCESS DATA

Json Xml

Similar Datasets

The fimbriae of enteroaggregative Escherichia coli induce epithelial inflammation in vitro and in a human intestinal xenograft model.

Project description:BackgroundEnteroaggregative Escherichia coli (EAEC) are increasingly recognized as an important agent of inflammatory and often persistent diarrhea. Although previous studies report on the inflammatory aspects of EAEC pathogenesis, the mechanisms by which EAEC trigger these events are not well understood.MethodsEAEC strains harboring mutations in known EAEC virulence determinants were tested in an in vitro model of transepithelial migration of polymorphonuclear neutrophils (PMNs) and in human intestinal xenografts in severe-combined immunodeficient (SCID-HU-INT) mice, a novel model for studying EAEC disease in vivo.ResultsExpression of aggregative adherence fimbriae (AAFs), the principal adhesins of EAEC, was required for EAEC-induced PMN transepithelial migration in vitro. Moreover, constructed plasmids encoding AAF gene clusters demonstrated that the AAF adhesins are sufficient for triggering this event in a nonpathogenic E. coli background. Furthermore, with use of the SCID-HU-INT mouse model, severe tissue damage and infiltration of inflammatory cells was observed in the human tissue after EAEC infection. These pathological marks were strongly related to AAF expression, thus clearly confirming our in vitro findings.ConclusionsThe present work establishes EAEC as an important inflammatory pathogen and the AAF adhesins as inducers of potentially detrimental immune responses.

| S-EPMC3491746 | biostudies-literature

New adhesin of enteroaggregative Escherichia coli related to the Afa/Dr/AAF family.

Project description:Enteroaggregative Escherichia coli (EAEC) is an important cause of diarrhea worldwide. We analyzed 17 Danish EAEC strains, isolated in the course of a case control study, for phenotypic and genotypic properties. The strains belonged to at least 14 different serotypes. Using PCR to investigate the prevalence of various putative virulence genes, we found that all but two strains were typical EAEC, as they harbored all or part of the previously described AggR regulon. The majority of the strains harbored genes encoding aggregative adherence fimbriae (AAF). The most common was AAF/I, found in nine strains; eight strains carried no known AAF-related genes. We utilized TnphoA mutagenesis to localize the aggregative adherence (AA) adhesin from one typical EAEC strain, C1010-00, which lacked a known AAF. We identified a TnphoA insertion in a hypothetical Dr-related pilin deposited in GenBank as HdaA. Four additional Danish strains harbored HdaA, and all but one displayed AA to HEp-2 cells. By using PCR primers derived from the pilins and ushers from the three AAF and Hda, we found that 16 of 17 strains exhibited evidence of one of these factors; importantly, the one negative strain also lacked the aggR gene. Cloning of the complete Hda gene cluster and expression in E. coli DH5alpha resulted in AA and complementation of the C1010-00 nonadherent mutant. Four related adhesins have now been found to confer AA in typical EAEC strains; our data suggest that, together, these variants may account for AA in the large majority of strains.

| S-EPMC2446688 | biostudies-literature

Crystal structure and analysis of HdaB: The enteroaggregative Escherichia coli AAF/IV pilus tip protein.

Project description:Enteroaggregative Escherichia coli is the primary cause of pediatric diarrhea in developing countries. They utilize aggregative adherence fimbriae (AAFs) to promote initial adherence to the host intestinal mucosa, promote the formation of biofilms, and mediate host invasion. Five AAFs have been identified to date and AAF/IV is amongst the most prevalent found in clinical isolates. Here we present the X-ray crystal structure of the AAF/IV tip protein HdaB at 2.0 Å resolution. It shares high structural homology with members of the Afa/Dr superfamily of fimbriae, which are involved in host invasion. We highlight surface exposed residues that share sequence homology and propose that these may function in invasion and also non-conserved regions that could mediate HdaB specific adhesive functions.

| S-EPMC5029526 | biostudies-literature

Structural insight into host recognition by aggregative adherence fimbriae of enteroaggregative Escherichia coli.

Project description:Enteroaggregative Escherichia coli (EAEC) is a leading cause of acute and persistent diarrhea worldwide. A recently emerged Shiga-toxin-producing strain of EAEC resulted in significant mortality and morbidity due to progressive development of hemolytic-uremic syndrome. The attachment of EAEC to the human intestinal mucosa is mediated by aggregative adherence fimbria (AAF). Using X-ray crystallography and NMR structures, we present new atomic resolution insight into the structure of AAF variant I from the strain that caused the deadly outbreak in Germany in 2011, and AAF variant II from archetype strain 042, and propose a mechanism for AAF-mediated adhesion and biofilm formation. Our work shows that major subunits of AAF assemble into linear polymers by donor strand complementation where a single minor subunit is inserted at the tip of the polymer by accepting the donor strand from the terminal major subunit. Whereas the minor subunits of AAF have a distinct conserved structure, AAF major subunits display large structural differences, affecting the overall pilus architecture. These structures suggest a mechanism for AAF-mediated adhesion and biofilm formation. Binding experiments using wild type and mutant subunits (NMR and SPR) and bacteria (ELISA) revealed that despite the structural differences AAF recognize a common receptor, fibronectin, by employing clusters of basic residues at the junction between subunits in the pilus. We show that AAF-fibronectin attachment is based primarily on electrostatic interactions, a mechanism not reported previously for bacterial adhesion to biotic surfaces.

| S-EPMC4169507 | biostudies-literature

Identification of an aggregative adhesion fimbria (AAF) type III-encoding operon in enteroaggregative Escherichia coli as a sensitive probe for detecting the AAF-encoding operon family.

Project description:Enteroaggregative Escherichia coli (EAEC) is recognized as an emerging cause of diarrhea in children and adults worldwide, and recent studies have implicated EAEC in persistent diarrhea in patients infected with human immunodeficiency virus (HIV). In this study, we identified aggregative adhesion fimbria type III (AAF-III) in isolate 55989, a typical EAEC strain. Analysis of the sequence of the plasmid-borne agg-3 gene cluster encoding AAF-III showed this cluster to be closely related to the agg and aaf operons and to the afa operons carried by diffusely adherent pathogenic E. coli. We investigated the adhesion properties of a collection of 25 EAEC strains isolated from HIV-infected patients presenting with persistent diarrhea. We found that a minority of strains (36%) carried sequences similar to those of the agg and aaf operons, which encode AAF-I and AAF-II, respectively. We developed PCR assays specific for the agg-3 operon. In our collection, the frequency of AAF-III strains was similar (12%) to that of AAF-I strains (16%) but higher than that of AAF-II isolates (0%). Differences between EAEC strains in terms of the virulence factors present render detection of these strains difficult with the available DNA probes. Based on comparison of the agg, aaf, and agg-3 operons, we defined an AAF probe internal to the adhesion gene clusters and demonstrated that it was efficient for the identification of EAEC strains. We investigated 32 EAEC isolates, of which only 34.4% were detected with the classical CVD432 probe (detecting pAA virulence plasmids) whereas 65.6% were detected with the AAF probe.

| S-EPMC128174 | biostudies-literature

Crystallization and initial crystallographic analysis of AafA: the major adhesive subunit of the enteroaggregative Escherichia coli AAF/II pilus.

Project description:AafA is the major adhesive pilin subunit of the aggregative adherence fimbriae (AAF) from enteroaggregative Escherichia coli, which play an important role by attaching to the host cells during the initial phase of bacterial colonization and invasion. AafA has been crystallized at pH 3.4 and diffraction data have been collected to 2.1 Å resolution. Molecular replacement was unsuccessful and selenomethionine-substituted protein and heavy-atom derivatives are being prepared for phasing.

| S-EPMC3080148 | biostudies-literature

Structural and functional studies of Escherichia coli aggregative adherence fimbriae (AAF/V) reveal a deficiency in extracellular matrix binding.

Project description:Enteroaggregative Escherichia coli (EAEC) is an emerging cause of acute and persistent diarrhea worldwide. The pathogenesis of different EAEC stains is complicated, however, the early essential step begins with attachment of EAEC to intestinal mucosa via aggregative adherence fimbriae (AAFs). Currently, five different variants have been identified, which all share a degree of similarity in the gene organization of their operons and sequences. Here, we report the solution structure of Agg5A from the AAF/V variant. While preserving the major structural features shared by all AAF members, only Agg5A possesses an inserted helix at the beginning of the donor strand, which together with altered surface electrostatics, renders the protein unable to interact with fibronectin. Hence, here we characterize the first AAF variant with a binding mode that varies from previously described AAFs.

| S-EPMC5289312 | biostudies-literature

Nitazoxanide inhibits biofilm production and hemagglutination by enteroaggregative Escherichia coli strains by blocking assembly of AafA fimbriae.

Project description:Enteroaggregative Escherichia coli (EAEC) strains have emerged as common causes of persistent diarrhea and malnutrition among children and HIV-infected persons. During infection, EAEC typically adheres to the intestinal mucosa via fimbrial adhesins, which results in a characteristic aggregative pattern. In the study described here we investigated whether the broad-spectrum antiparasitic and antidiarrheal drug nitazoxanide (NTZ) might be active against EAEC in vitro. While E. coli strains were resistant to NTZ in rich Luria-Bertani medium (MIC > 64 microg/ml), the drug was slightly inhibitory in a minimal medium supplemented with glucose (MinA-G medium; MIC, approximately 32 microg/ml). NTZ also inhibited biofilm production by strain EAEC 042 in both Dulbecco's modified Eagle's medium and MinA-G medium with a 50% inhibitory concentration of approximately 12 microg/ml. Immunofluorescence and immunoblot analyses with antibody against the major fimbrial subunit AafA of aggregative adherence fimbriae vaariant II (AAF/II) established that the numbers of AAF/II filaments on bacteria grown in the presence of NTZ were dramatically reduced. Comparative quantitative reverse transcription-PCR and reporter gene fusions (aafA::phoA) indicated that aafA expression was unaffected by NTZ, while aggR transcript levels and aggR::lacZ expression were increased approximately 10- and 2.5-fold, respectively, compared with that for the untreated controls. More generally, NTZ inhibited hemagglutination (HA) of red blood cells by the non-biofilm-producing strain JM221 expressing either AAF/I or type I fimbriae. Our findings suggest that the inhibitory action of NTZ on biofilm formation and HA is likely due to inhibition of fimbrial assembly. Antimicrobial agents that inhibit the assembly or function of fimbrial filaments should be good candidates for the prevention of infection.

| S-EPMC2849362 | biostudies-literature

A Novel pAA Virulence Plasmid Encoding Toxins and Two Distinct Variants of the Fimbriae of Enteroaggregative Escherichia coli.

Project description:Enteroaggregative Escherichia coli (EAEC) is an increasingly recognized pathogen associated with acute and persistent diarrhea worldwide. While EAEC strains are considered highly heterogeneous, aggregative adherence fimbriae (AAFs) are thought to play a pivotal role in pathogenicity by facilitating adherence to the intestinal mucosa. In this study, we optimized an existing multiplex PCR to target all known AAF variants, which are distinguished by differences in their pilin subunits. We applied the assay on a collection of 162 clinical Danish EAEC strains and interestingly found six, by SNP analysis phylogenetically distinct, strains harboring the major pilin subunits from both AAF/III and AAF/V. Whole-genome and plasmid sequencing revealed that in these six strains the agg3A and agg5A genes were located on a novel pAA plasmid variant. Moreover, the plasmid also encoded several other virulence genes including some not previously found on pAA plasmids. Thus, this plasmid endows the host strains with a remarkably high number of EAEC associated virulence genes hereby likely promoting strain pathogenicity.

| S-EPMC5320562 | biostudies-literature

Plasmid-encoded toxin of enteroaggregative Escherichia coli is internalized by epithelial cells.

Project description:We have previously described a 104-kDa protein termed Pet (for plasmid-encoded toxin) secreted by some strains of enteroaggregative Escherichia coli (EAEC). Through an unknown mechanism, this toxin (i) raises transepithelial short-circuit current (Isc) and decreases the electrical resistance of rat jejunum mounted in the Ussing chamber, (ii) causes cytoskeletal alterations in HEp-2 cells and HT29/C1 cells, and (iii) is required for histopathologic effects of EAEC on human intestinal mucosa. Pet is a member of the autotransporter class of secreted proteins and together with Tsh, EspP, EspC, ShMu, and SepA proteins comprises the SPATE subfamily. Here, we show that Pet is internalized by HEp-2 cells and that internalization appears to be required for the induction of cytopathic effects. Evidence supporting Pet internalization includes the facts that (i) the effects of Pet on epithelial cells were inhibited by brefeldin A, which interferes with various steps of intracellular vesicular transport; (ii) immunoblots using anti-Pet antibodies detected Pet in the cytoplasmic fraction of intoxicated HEp-2 cells; (iii) Pet was detected inside HEp-2 cells by confocal microscopy; and (iv) a mutant in the passenger domain cleavage site, which prevents Pet release from the bacterial outer membrane, did not produce cytopathic effects on epithelial cells, whereas the release of mutant Pet from the outer membrane with trypsin yielded active toxin. We have also shown that the Pet serine protease motif is required to produce cytopathic effects but not for Pet secretion. Our results suggest an intracellular mode of action for the Pet protease and are consistent with we our recent report suggesting an intracellular mode of action for Pet.

| S-EPMC97986 | biostudies-literature

OmicsDI is part of the ELIXIR infrastructure

OmicsDI is an Elixir interoperability service. Learn more ›

Tweets

OmicsDI Databases

PRIDE
PeptideAtlas
MassIVE
JPOST Repository
Physiome Model Repository

EGA
EVA
ENA
LINCS
PAXDB
Cell Collective

MetaboLights
Metabolomics Workbench
MetabolomeExpress
GNPS
BioModels
FAIRDOMHub

ArrayExpress
dbGaP
ExpressionAtlas
GEO
NODE

Information

Databases
Help
API
Contact us
Code on GitHub
Terms of use
Submit Data