Interaction between Campylobacter and intestinal epithelial cells leads to a different proinflammatory response in human and porcine host

Salmonella typhimurium is a gram-negative enteric pathogen that invades the mucosal epithelium and is associated with diarrheal illness in humans. Flagellin from S. typhimurium and other gram-negative bacteria has been shown to be the predominant proinflammatory mediator through activation of the basolateral Toll-like receptor 5 (TLR5). Recent evidence has shown that prior exposure can render immune cells tolerant to subsequent challenges by TLR ligands. Accordingly, we examined whether prior exposure to purified flagellin would render human intestinal epithelial cells insensitive to future contact. We found that flagellin-induced tolerance is common to polarized epithelial cells and prevents further activation of proinflammatory signaling cascades by both purified flagellin and Salmonella bacteria but does not affect TNF-α stimulation of the same pathways. Flagellin tolerance is a rapid process that does not require protein synthesis, and that occurs within 1 to 2 h of flagellin exposure. Prolonged flagellin exposure blocks activation of the NF-κB, MAPK, and phosphoinositol 3-kinase signaling pathways and results in the internalization of a fraction of the basolateral TLR5 without affecting the polarity or total expression of TLR5. After removal of flagellin, cells require more than 24 h to fully recover their ability to mount a normal proinflammatory response. We have found that activation of phosphoinositol 3-kinase and Akt by flagellin has a small damping effect in the early stages of flagellin signaling but is not responsible for tolerance. Our study indicates that inhibition of TLR5-associated IL-1 receptor-associated kinase-4 activity occurs during the development of flagellin tolerance and is likely to be the cause of tolerance.

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PKCζ participates in activation of inflammatory response induced by enteropathogenicE. coli

AJP Cell Physiology ◽

10.1152/ajpcell.00444.2002 ◽

2003 ◽

Vol 285 (3) ◽

pp. C512-C521 ◽

Cited By ~ 52

Author(s):

Suzana D. Savkovic ◽

Athanasia Koutsouris ◽

Gail Hecht

Keyword(s):

Epithelial Cells ◽

Kinase Activity ◽

Intestinal Epithelial Cells ◽

Fold Increase ◽

Serine Phosphorylation ◽

Intestinal Epithelial ◽

Proinflammatory Response ◽

Independent Events ◽

Iκb Kinase ◽

Iκbα Phosphorylation

We showed previously that enteropathogenic Escherichia coli (EPEC) infection of intestinal epithelial cells induces inflammation by activating NF-κB and upregulating IL-8 expression. We also reported that extracellular signal-regulated kinases (ERKs) participate in EPEC-induced NF-κB activation but that other signaling molecules such as PKCζ may be involved. The aim of this study was to determine whether PKCζ is activated by EPEC and to investigate whether it also plays a role in EPEC-associated inflammation. EPEC infection induced the translocation of PKCζ from the cytosol to the membrane and its activation as determined by kinase activity assays. Inhibition of PKCζ by the pharmacological inhibitor rottlerin, the inhibitory myristoylated PKCζ pseudosubstrate (MYR-PKCζ-PS), or transient expression of a nonfunctional PKCζ significantly suppressed EPEC-induced IκBα phosphorylation. Although PKCζ can activate ERK, MYR-PKCζ-PS had no effect on EPEC-induced stimulation of this pathway, suggesting that they are independent events. PKCζ can regulate NF-κB activation by interacting with and activating IκB kinase (IKK). Coimmunoprecipitation studies showed that the association of PKCζ and IKK increased threefold 60 min after infection. Kinase activity assays using immunoprecipitated PKCζ-IKK complexes from infected intestinal epithelial cells and recombinant IκBα as a substrate showed a 2.5-fold increase in IκBα phosphorylation. PKCζ can also regulate NF-κB by serine phosphorylation of the p65 subunit. Serine phosphorylation of p65 was increased after EPEC infection but could not be consistently attenuated by MYR-PKCζ-PS, suggesting that other signaling events may be involved in this particular arm of NF-κB regulation. We speculate that EPEC infection of intestinal epithelial cells activates several signaling pathways including PKCζ and ERK that lead to NF-κB activation, thus ensuring the proinflammatory response.

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Cell Surface-Associated Elongation Factor Tu Mediates the Attachment of Lactobacillus johnsonii NCC533 (La1) to Human Intestinal Cells and Mucins

Infection and Immunity ◽

10.1128/iai.72.4.2160-2169.2004 ◽

2004 ◽

Vol 72 (4) ◽

pp. 2160-2169 ◽

Cited By ~ 256

Author(s):

Dominique Granato ◽

Gabriela E. Bergonzelli ◽

Raymond David Pridmore ◽

Laure Marvin ◽

Martine Rouvet ◽

...

Keyword(s):

Epithelial Cells ◽

Intestinal Epithelial Cells ◽

Binding Capacity ◽

Elongation Factor ◽

Mass Spectrometry Analysis ◽

Intestinal Cells ◽

Elongation Factor Tu ◽

Intestinal Epithelial ◽

Lactobacillus Johnsonii ◽

Proinflammatory Response

ABSTRACT The aim of this work was to identify Lactobacillus johnsonii NCC533 (La1) surface molecules mediating attachment to intestinal epithelial cells and mucins. Incubation of Caco-2 intestinal epithelial cells with an L. johnsonii La1 cell wall extract led to the recognition of elongation factor Tu (EF-Tu) as a novel La1 adhesin-like factor. The presence of EF-Tu at the surface of La1 was confirmed by analysis of purified outer surface protein extract by immunoblotting experiments, by electron microscopy, and by enzyme-linked immunosorbent assays of live bacteria. Furthermore, tandem mass spectrometry analysis proved that EF-TU was expressed at the La1 surface as an intact molecule. Using recombinant La1 EF-Tu protein, we were able to determine that its binding to intestinal cells and to mucins is pH dependent. Competition experiments suggested that EF-Tu has an important role in La1 mucin binding capacity. In addition, immunomodulation studies performed on HT29 cells showed that EF-Tu recombinant protein can induce a proinflammatory response in the presence of soluble CD14. Our in vitro results indicate that EF-Tu, through its binding to the intestinal mucosa, might participate in gut homeostasis.

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PepT1 mediates transport of the proinflammatory bacterial tripeptide l-Ala-γ-d-Glu-meso-DAP in intestinal epithelial cells

AJP Gastrointestinal and Liver Physiology ◽

10.1152/ajpgi.00527.2009 ◽

2010 ◽

Vol 299 (3) ◽

pp. G687-G696 ◽

Cited By ~ 50

Author(s):

Guillaume Dalmasso ◽

Hang Thi Thu Nguyen ◽

Laetitia Charrier-Hisamuddin ◽

Yutao Yan ◽

Hamed Laroui ◽

...

Keyword(s):

Epithelial Cells ◽

Map Kinases ◽

Intestinal Inflammation ◽

Intestinal Epithelial Cells ◽

Breakdown Product ◽

Specific Substrate ◽

Dependent Manner ◽

Intestinal Epithelial ◽

Proinflammatory Response ◽

Chemokine Production

PepT1 is a di/tripeptide transporter highly expressed in the small intestine, but poorly or not expressed in the colon. However, during chronic inflammation, such as inflammatory bowel disease, PepT1 expression is induced in the colon. Commensal bacteria that colonize the human colon produce a large amount of di/tripeptides. To date, two bacterial peptides ( N-formylmethionyl-leucyl-phenylalanine and muramyl dipeptide) have been identified as substrates of PepT1. We hypothesized that the proinflammatory tripeptide l-Ala-γ-d-Glu- meso-DAP (Tri-DAP), a breakdown product of bacterial peptidoglycan, is transported into intestinal epithelial cells via PepT1. We found that uptake of glycine-sarcosine, a specific substrate of PepT1, in intestinal epithelial Caco2-BBE cells was inhibited by Tri-DAP in a dose-dependent manner. Tri-DAP induced activation of NF-κB and MAP kinases, consequently leading to production of the proinflammatory cytokine interleukin-8. Tri-DAP-induced inflammatory response in Caco2-BBE cells was significantly suppressed by silencing of PepT1 expression by using PepT1-shRNAs in a tetracycline-regulated expression ( Tet-off) system. Colonic epithelial HT29-Cl.19A cells, which do not express PepT1 under basal condition, were mostly insensitive to Tri-DAP-induced inflammation. However, HT29-Cl.19A cells exhibited proinflammatory response to Tri-DAP upon stable transfection with a plasmid encoding PepT1. Accordingly, Tri-DAP significantly increased keratinocyte-derived chemokine production in colonic tissues from transgenic mice expressing PepT1 in intestinal epithelial cells. Finally, Tri-DAP induced a significant drop in intracellular pH in intestinal epithelial cells expressing PepT1, but not in cells that did not express PepT1. Our data collectively support the classification of Tri-DAP as a novel substrate of PepT1. Given that PepT1 is highly expressed in the colon during inflammation, PepT1-mediated Tri-DAP transport may occur more effectively during such conditions, further contributing to intestinal inflammation.

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Brucella invasion of human intestinal epithelial cells elicits a weak proinflammatory response but a significant CCL20 secretion

FEMS Immunology & Medical Microbiology ◽

10.1111/j.1574-695x.2012.00985.x ◽

2012 ◽

Vol 66 (1) ◽

pp. 45-57 ◽

Cited By ~ 11

Author(s):

Mariana C. Ferrero ◽

Carlos A. Fossati ◽

Martín Rumbo ◽

Pablo C. Baldi

Keyword(s):

Epithelial Cells ◽

Intestinal Epithelial Cells ◽

Intestinal Epithelial ◽

Proinflammatory Response ◽

Human Intestinal Epithelial Cells

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Long-chain polyunsaturated fatty acids attenuate the IL-1β-induced proinflammatory response in human fetal intestinal epithelial cells

Pediatric Research ◽

10.1038/pr.2015.154 ◽

2015 ◽

Vol 78 (6) ◽

pp. 626-633 ◽

Cited By ~ 11

Author(s):

Vasuki Wijendran ◽

J. T. Brenna ◽

Dong Hao Wang ◽

Weishu Zhu ◽

Di Meng ◽

...

Keyword(s):

Fatty Acids ◽

Epithelial Cells ◽

Polyunsaturated Fatty Acids ◽

Intestinal Epithelial Cells ◽

Intestinal Epithelial ◽

Proinflammatory Response ◽

Long Chain

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Activation of proinflammatory response in human intestinal epithelial cells followingVibrio choleraeinfection through PI3K/Akt pathway

Canadian Journal of Microbiology ◽

10.1139/w09-093 ◽

2009 ◽

Vol 55 (11) ◽

pp. 1310-1318 ◽

Cited By ~ 9

Author(s):

Arunava Bandyopadhaya ◽

Swati Bhowmick ◽

Keya Chaudhuri

Keyword(s):

Epithelial Cells ◽

Intestinal Epithelial Cells ◽

Intestinal Epithelial ◽

Akt Signaling Pathway ◽

Proinflammatory Response ◽

Akt Activation ◽

Human Intestinal Epithelial Cells ◽

Tnf Α ◽

Bacterial Genes ◽

Insertion Mutants

Vibrio cholerae activates proinflammatory response in cultured intestinal epithelial cells. In this study, we demonstrate that V. cholerae O395 infection of intestinal epithelial cells results in the activation of Akt. Inhibition of Akt significantly decreases IL-1α, IL-6, and TNF-α production in V. cholerae infected Int407 cells. Analysis of the mechanisms of Akt influences on cytokine response demonstrates that Akt promotes NF-κB activation. We have extended these findings to show that Akt activation may be regulated by bacterial genes associated with virulence, adherence, or motility. Insertion mutants in the virulence genes coding for CtxA, ToxT, and OmpU of V. cholerae modulate the activation of PI3K/Akt signaling pathway, whereas an aflagellate non-motile mutant (O395FLAN) and a adherent and less motile mutant (O395Y3N/O395Y4N) of V. cholerae both show very significant down-regulation of Akt activity in Int407 cells. Together, these observations indicate that Akt promotes proinflammatory cytokine production by V. cholerae infected human intestinal epithelial cells through its influences on NF-κB.

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