Interaction of cholera toxin and Escherichia coli enterotoxin with isolated intestinal epithelial cells

The interaction of biologically active 125I-labeled cholera toxin with isolated chick intestinal epithelial cells involves a large number (approx 1.7 10(6)/cell) of high-affinity (Kd = 8–9 X 10(-9) M) binding sites that belong to a single class. Binding of iodotoxin to the cells occurs rapidly, is half-maximal within 1 min, and is complete in 3–7 min (at 37 degrees C) depending on the toxin concentration. Toxin binding is saturable and includes only a small contribution from nonspecific sites. Ligand competition studies suggest that the isolated B subunit of choleragen (CT-B) behaves in an almost identical fashion to the holotoxin (CT), whereas the A subunit shows no detectable activity in competitive binding. Assays for cAMP indicate that neither that A nor the B subunits of CT contain any activity for increasing the level of intracellular cAMP. B subunit, when incubated with CT, inhibits CT-induced elevation of cAMP in a dose-dependent manner. Preincubation of 125I-CT with various concentrations of ganglioside GM1 also shows a dose-dependent inhibitory effect on the binding activity of the toxin. Pretreatment of CT with increasing concentrations of GM1 results in a progressive decrease in toxin-induced formation of cAMP. Escherichia coli heat-labile enterotoxin, which is known to alter intestinal function via a mechanism similar to that of CT, has binding and biological effects very similar to thoseof CT.

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Effects of Stearic Acid on Proliferation, Differentiation, Apoptosis, and Autophagy in Porcine Intestinal Epithelial Cells

Current Molecular Medicine ◽

10.2174/1566524019666190917144127 ◽

2020 ◽

Vol 20 (2) ◽

pp. 157-166

Author(s):

Yuan Yang ◽

Jin Huang ◽

Jianzhong Li ◽

Huansheng Yang ◽

Yulong Yin

Keyword(s):

Cell Differentiation ◽

Epithelial Cells ◽

Stearic Acid ◽

Er Stress ◽

Intestinal Epithelial Cells ◽

Dependent Manner ◽

Intestinal Epithelial ◽

High Concentrations ◽

Induced Apoptosis ◽

Dose Dependent

Background: Stearic acid (SA), a saturated long-chain fatty acid consisting of 18 carbon atoms, is widely found in feed ingredients, such as corn, soybeans, and wheat. However, the roles of SA in the renewal of intestinal epithelial cells remain unclear. Methods and Results: In the present study, we found that 0.01-0.1 mM SA promoted IPEC-J2 cell differentiation and did not affect IPEC-J2 cell viability. In addition, the results showed that the viability of IPEC-J2 cells was inhibited by SA in a time- and dose-dependent manner at high concentrations. Flow cytometry and western blot analysis suggested that SA induced apoptosis, autophagy and ER stress in cells. In addition, the amounts of triglyceride were significantly increased upon challenge with SA. Moreover, the decrease in the viability of cells induced by SA could be attenuated by 4-PBA, an inhibitor of ER stress. Conclusion: In summary, SA accelerated IPEC-J2 cell differentiation at 0.01-0.1 mM. Furthermore, SA induced IPEC-J2 cell apoptosis and autophagy by causing ER stress.

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Flagellin-Dependent and -Independent Inflammatory Responses following Infection by Enteropathogenic Escherichia coli and Citrobacter rodentium

Infection and Immunity ◽

10.1128/iai.01141-07 ◽

2008 ◽

Vol 76 (4) ◽

pp. 1410-1422 ◽

Cited By ~ 59

Author(s):

Mohammed A. Khan ◽

Saeid Bouzari ◽

Caixia Ma ◽

Carrie M. Rosenberger ◽

Kirk S. B. Bergstrom ◽

...

Keyword(s):

Escherichia Coli ◽

Epithelial Cells ◽

Diarrheal Disease ◽

Intestinal Inflammation ◽

Inflammatory Responses ◽

Intestinal Epithelial Cells ◽

Mitogen Activated Protein Kinase ◽

Dependent Manner ◽

Intestinal Epithelial ◽

Citrobacter Rodentium

ABSTRACT Enteropathogenic Escherichia coli (EPEC) and the murine pathogen Citrobacter rodentium belong to the attaching and effacing (A/E) family of bacterial pathogens. These noninvasive bacteria infect intestinal enterocytes using a type 3 secretion system (T3SS), leading to diarrheal disease and intestinal inflammation. While flagellin, the secreted product of the EPEC fliC gene, causes the release of interleukin 8 (IL-8) from epithelial cells, it is unclear whether A/E bacteria also trigger epithelial inflammatory responses that are FliC independent. The aims of this study were to characterize the FliC dependence or independence of epithelial inflammatory responses to direct infection by EPEC or C. rodentium. Following infection of Caco-2 intestinal epithelial cells by wild-type and ΔfliC EPEC, a rapid activation of several proinflammatory genes, including those encoding IL-8, monocyte chemoattractant protein 1, macrophage inflammatory protein 3α (MIP3α), and β-defensin 2, occurred in a FliC-dependent manner. These responses were accompanied by mitogen-activated protein kinase activation, as well as the Toll-like receptor 5 (TLR5)-dependent activation of NF-κB. At later infection time points, a subset of these proinflammatory genes (IL-8 and MIP3α) was also induced in cells infected with ΔfliC EPEC. The nonmotile A/E pathogen C. rodentium also triggered similar innate responses through a TLR5-independent but partially NF-κB-dependent mechanism. Moreover, the EPEC FliC-independent responses were increased in the absence of the locus of enterocyte effacement-encoded T3SS, suggesting that translocated bacterial effectors suppress rather than cause the FliC-independent inflammatory response. Thus, we demonstrate that infection of intestinal epithelial cells by A/E pathogens can trigger an array of proinflammatory responses from epithelial cells through both FliC-dependent and -independent pathways, expanding our understanding of the innate epithelial response to infection by these pathogens.

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Interaction of Cholera Toxin B Subunit with Rat Intestinal Epithelial Cells

Russian Journal of Bioorganic Chemistry ◽

10.1134/s1068162018030123 ◽

2018 ◽

Vol 44 (4) ◽

pp. 403-407

Author(s):

E. V. Navolotskaya ◽

V. B. Sadovnikov ◽

D. V. Zinchenko ◽

V. I. Vladimirov ◽

Y. A. Zolotarev

Keyword(s):

Epithelial Cells ◽

Cholera Toxin ◽

Intestinal Epithelial Cells ◽

Cholera Toxin B Subunit ◽

Intestinal Epithelial ◽

Toxin B ◽

Cholera Toxin B ◽

B Subunit

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NF-κB- and AP-1-Mediated Induction of Human Beta Defensin-2 in Intestinal Epithelial Cells by Escherichia coli Nissle 1917: a Novel Effect of a Probiotic Bacterium

Infection and Immunity ◽

10.1128/iai.72.10.5750-5758.2004 ◽

2004 ◽

Vol 72 (10) ◽

pp. 5750-5758 ◽

Cited By ~ 306

Author(s):

Jan Wehkamp ◽

Jürgen Harder ◽

Kai Wehkamp ◽

Birte Wehkamp-von Meissner ◽

Miriam Schlee ◽

...

Keyword(s):

Escherichia Coli ◽

Epithelial Cells ◽

Intestinal Epithelial Cells ◽

Selective Inhibitor ◽

Probiotic Bacteria ◽

Mucosal Cell ◽

Dependent Manner ◽

Intestinal Epithelial ◽

E Coli ◽

Innate Defense

ABSTRACT Little is known about the defensive mechanisms induced in epithelial cells by pathogenic versus probiotic bacteria. The aim of our study was to compare probiotic bacterial strains such as Escherichia coli Nissle 1917 with nonprobiotic, pathogenic and nonpathogenic bacteria with respect to innate defense mechanisms in the intestinal mucosal cell. Here we report that E. coli strain Nissle 1917 and a variety of other probiotic bacteria, including lactobacilli—in contrast to more than 40 different E. coli strains tested—strongly induce the expression of the antimicrobial peptide human beta-defensin-2 (hBD-2) in Caco-2 intestinal epithelial cells in a time- and dose-dependent manner. Induction of hBD-2 through E. coli Nissle 1917 was further confirmed by activation of the hBD-2 promoter and detection of the hBD-2 peptide in the culture supernatants of E. coli Nissle 1917-treated Caco-2 cells. Luciferase gene reporter analyses and site-directed mutagenesis experiments demonstrated that functional binding sites for NF-κB and AP-1 in the hBD-2 promoter are required for induction of hBD-2 through E. coli Nissle 1917. Treatment with the NF-κB inhibitor Helenalin, as well as with SP600125, a selective inhibitor of c-Jun N-terminal kinase, blocked hBD-2 induction by E. coli Nissle 1917 in Caco-2 cells. SB 202190, a specific p38 mitogen-activated protein kinase inhibitor, and PD 98059, a selective inhibitor of extracellular signal-regulated kinase 1/2, were ineffective. This report demonstrates that probiotic bacteria may stimulate the intestinal innate defense through the upregulation of inducible antimicrobial peptides such as hBD-2. The induction of hBD-2 may contribute to an enhanced mucosal barrier to the luminal bacteria.

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Sheep β-Defensin 2 Regulates Escherichia coli F17 Resistance via NF-κB and MAPK Signaling Pathways in Ovine Intestinal Epithelial Cells

Biology ◽

10.3390/biology10121356 ◽

2021 ◽

Vol 10 (12) ◽

pp. 1356

Author(s):

Ling Ge ◽

Shuangxia Zou ◽

Zehu Yuan ◽

Weihao Chen ◽

Shanhe Wang ◽

...

Keyword(s):

Escherichia Coli ◽

Epithelial Cells ◽

Signaling Pathways ◽

Intestinal Epithelial Cells ◽

Mapk Signaling ◽

Dependent Manner ◽

Intestinal Epithelial ◽

E Coli ◽

Mapk Signaling Pathways ◽

Mapk Inhibitor

Escherichia coli (E. coli) F17 is a member of enterotoxigenic Escherichia coli, which can cause massive diarrhea and high mortality in newborn lambs. β-defensin is mainly produced by the epithelial tissue of the gastrointestinal tract in response to microbial infection. However, the molecular mechanism of sheep β-defensin 2 (SBD-2) against E. coli F17 remains unclear. This study aims to reveal the antibacterial ability of SBD-2 against E. coli F17 infection in sheep. Firstly, we established the culture system of ovine intestinal epithelial cells (OIECs) in vitro, treated with different concentrations of E. coli F17 for an indicated time. Secondly, we performed RNA interference and overexpression to investigate the effect of SBD-2 expression on E. coli F17 adhesion to OIECs. Finally, inhibitors of NF-κB and MAPK pathways were pre-treated to explore the possible relationship involving in E. coli F17 infection regulating SBD-2 expression. The results showed that E. coli F17 markedly (p < 0.01) upregulated the expression levels of SBD-2 mRNA and protein in a concentration- and time-dependent manner. Overexpression of SBD-2 contributed to enhancing E. coli F17 resistance in OIECs, while silencing SBD-2 dramatically improved the adhesion of E. coli F17 to OIECs (p < 0.05 or p < 0.01). Furthermore, E. coli F17 stimulated SBD-2 expression was obviously decreased by pre-treatment with NF-κB inhibitor PDTC, p38 MAPK inhibitor SB202190 and ERK1/2 MAPK inhibitor PD98095 (p < 0.05 or p < 0.01). Interestingly, adhesion of E. coli F17 to OIECs were highly enhanced by pre-treated with PDTC, SB202190 and PD98095. Our data suggested that SBD-2 could inhibit E. coli F17 infection in OIECs, possibly through NF-κB and MAPK signaling pathways. Our results provide useful theoretical basis on developing anti-infective drug and breeding for E. coli diarrhea disease-resistant sheep.

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