Agglutinating Secretory IgA Preserves Intestinal Epithelial Cell Integrity during Apical Infection by Shigella flexneri

ABSTRACTShigella flexneri, by invading intestinal epithelial cells (IECs) and inducing inflammatory responses of the colonic mucosa, causes bacillary dysentery. Although M cells overlying Peyer's patches are commonly considered the primary site of entry ofS. flexneri, indirect evidence suggests that bacteria can also use IECs as a portal of entry to the lamina propria. Passive delivery of secretory IgA (SIgA), the major immunoglobulin secreted at mucosal surfaces, has been shown to protect rabbits from experimental shigellosis, but no information exists as to its molecular role in maintaining luminal epithelial integrity. We have established that the interaction of virulentS. flexneriwith the apical pole of a model intestinal epithelium consisting of polarized Caco-2 cell monolayers resulted in the progressive disruption of the tight junction network and actin depolymerization, eventually resulting in cell death. The lipopolysaccharide (LPS)-specific agglutinating SIgAC5 monoclonal antibody (MAb), but not monomeric IgAC5 or IgGC20 MAbs of the same specificity, achieved protective functions through combined mechanisms, including limitation of the interaction betweenS. flexneriand epithelial cells, maintenance of the tight junction seal, preservation of the cell morphology, reduction of NF-κB nuclear translocation, and inhibition of proinflammatory mediator secretion. Our results add to the understanding of the function of SIgA-mediated immune exclusion by identifying a mode of action whereby the formation of immune complexes translates into maintenance of the integrity of epithelial cells lining the mucosa. This novel mechanism of protection mediated by SIgA is important to extend the arsenal of effective strategies to fight againstS. flexnerimucosal invasion.

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Transient Suppression of Shigella flexneri Type 3 Secretion by a Protective O-Antigen-Specific Monoclonal IgA

mBio ◽

10.1128/mbio.00042-11 ◽

2011 ◽

Vol 2 (3) ◽

Cited By ~ 22

Author(s):

Stephen J. Forbes ◽

Tia Bumpus ◽

Elizabeth A. McCarthy ◽

Blaise Corthésy ◽

Nicholas J. Mantis

Keyword(s):

Epithelial Cells ◽

Mucosal Immunity ◽

Intestinal Epithelial Cells ◽

Shigella Flexneri ◽

Secretory Iga ◽

Bacterial Invasion ◽

Intestinal Epithelial ◽

Content Type ◽

O Antigen ◽

Type 3

ABSTRACTMucosal immunity to the enteric pathogenShigella flexneriis mediated by secretory IgA (S-IgA) antibodies directed against the O-antigen (O-Ag) side chain of lipopolysaccharide. While secretory antibodies against the O-Ag are known to prevent bacterial invasion of the intestinal epithelium, the mechanisms by which this occurs are not fully understood. In this study, we report that the binding of a murine monoclonal IgA (IgAC5) to the O-Ag ofS. flexneriserotype 5a suppresses activity of the type 3 secretion (T3S) system, which is necessary forS. flexnerito gain entry into intestinal epithelial cells. IgAC5’s effects on the T3S were rapid (5 to 15 min) and were coincident with a partial reduction in the bacterial membrane potential and a decrease in intracellular ATP levels. Activity of the T3S system returned to normal levels 45 to 90 min following antibody treatment, demonstrating that IgAC5’s effects were transient. Nonetheless, these data suggest a model in which the association of IgA with the O-Ag ofS. flexneripartially de-energizes the T3S system and temporarily renders the bacterium incapable of invading intestinal epithelial cells.IMPORTANCESecretory IgA (S-IgA) serves as the first line of defense against enteric infections. However, despite its well-recognized role in mucosal immunity, relatively little is known at the molecular level about how this class of antibody functions to prevent pathogenic bacteria from penetrating the epithelial barrier. It is generally assumed that S-IgA functions primarily by “immune exclusion,” a phenomenon in which the antibody binds to microbial surface antigens and thereby promotes bacterial agglutination, entrapment in mucus, and physical clearance from the gastrointestinal tract via peristalsis. The results of the present study suggest that in addition to serving as a physical barrier, S-IgA may have a direct impact on the ability of microbial pathogens to secrete virulence factors required for invasion of intestinal epithelial cells.

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Shigella flexneri regulates tight junction-associated proteins in human intestinal epithelial cells

Cellular Microbiology ◽

10.1046/j.1462-5822.2002.00197.x ◽

2002 ◽

Vol 4 (6) ◽

pp. 367-381 ◽

Cited By ~ 86

Author(s):

Takanori Sakaguchi ◽

Henrik Kohler ◽

Xiubin Gu ◽

Beth A. McCormick ◽

Hans-Christian Reinecker

Keyword(s):

Epithelial Cells ◽

Tight Junction ◽

Intestinal Epithelial Cells ◽

Shigella Flexneri ◽

Intestinal Epithelial ◽

Human Intestinal Epithelial Cells ◽

Associated Proteins

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Anti-Inflammatory Properties of Streptococcus salivarius, a Commensal Bacterium of the Oral Cavity and Digestive Tract

Applied and Environmental Microbiology ◽

10.1128/aem.03133-13 ◽

2013 ◽

Vol 80 (3) ◽

pp. 928-934 ◽

Cited By ~ 50

Author(s):

Ghalia Kaci ◽

Denise Goudercourt ◽

Véronique Dennin ◽

Bruno Pot ◽

Joël Doré ◽

...

Keyword(s):

Epithelial Cells ◽

Oral Cavity ◽

Mononuclear Cells ◽

Inflammatory Responses ◽

Intestinal Epithelial Cells ◽

Intestinal Epithelial ◽

Streptococcus Salivarius ◽

Content Type ◽

Anti Inflammatory

ABSTRACTStreptococcus salivariusis one of the first colonizers of the human oral cavity and gut after birth and therefore may contribute to the establishment of immune homeostasis and regulation of host inflammatory responses. The anti-inflammatory potential ofS. salivariuswas first evaluatedin vitroon human intestinal epithelial cells and human peripheral blood mononuclear cells. We show that liveS. salivariusstrains inhibitedin vitrothe activation of the NF-κB pathway on intestinal epithelial cells. We also demonstrate that the liveS. salivariusJIM8772 strain significantly inhibited inflammation in severe and moderate colitis mouse models. Thesein vitroandin vivoanti-inflammatory properties were not found with heat-killedS. salivarius, suggesting a protective response exclusively with metabolically active bacteria.

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Bacteroides fragilis Enterotoxin Upregulates Heme Oxygenase-1 in Intestinal Epithelial Cells via a Mitogen-Activated Protein Kinase- and NF-κB-Dependent Pathway, Leading to Modulation of Apoptosis

Infection and Immunity ◽

10.1128/iai.00191-16 ◽

2016 ◽

Vol 84 (9) ◽

pp. 2541-2554 ◽

Cited By ~ 11

Author(s):

Su Hyuk Ko ◽

Da Jeong Rho ◽

Jong Ik Jeon ◽

Young-Jeon Kim ◽

Hyun Ae Woo ◽

...

Keyword(s):

Epithelial Cells ◽

Heme Oxygenase ◽

Inflammatory Responses ◽

Intestinal Epithelial Cells ◽

Bacteroides Fragilis ◽

Heme Oxygenase 1 ◽

Intestinal Epithelial ◽

Content Type ◽

Iκb Kinase ◽

Mitogen Activated Protein

TheBacteroides fragilisenterotoxin (BFT), a virulence factor of enterotoxigenicB. fragilis(ETBF), interacts with intestinal epithelial cells and can provoke signals that induce mucosal inflammation. Although expression of heme oxygenase-1 (HO-1) is associated with regulation of inflammatory responses, little is known about HO-1 induction in ETBF infection. This study was conducted to investigate the effect of BFT on HO-1 expression in intestinal epithelial cells. Stimulation of intestinal epithelial cells with BFT resulted in upregulated expression of HO-1. BFT activated transcription factors such as NF-κB, AP-1, and Nrf2 in intestinal epithelial cells. Upregulation of HO-1 in intestinal epithelial cells was dependent on activated IκB kinase (IKK)–NF-κB signals. However, suppression of Nrf2 or AP-1 signals in intestinal epithelial cells did not result in significant attenuation of BFT-induced HO-1 expression. HO-1 induction via IKK–NF-κB in intestinal epithelial cells was regulated by p38 mitogen-activated protein kinases (MAPKs). Furthermore, suppression of HO-1 activity led to increased apoptosis in BFT-stimulated epithelial cells. These results suggest that a signaling pathway involving p38 MAPK–IKK–NF-κB in intestinal epithelial cells is required for HO-1 induction during exposure to BFT. Following this induction, increased HO-1 expression may regulate the apoptotic process in responses to BFT stimulation.

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Induction of Inflammatory Responses in Splenocytes by Exosomes Released from Intestinal Epithelial Cells followingCryptosporidium parvumInfection

Infection and Immunity ◽

10.1128/iai.00705-18 ◽

2019 ◽

Vol 87 (4) ◽

Cited By ~ 2

Author(s):

Yang Wang ◽

Yujuan Shen ◽

Hua Liu ◽

Jianhai Yin ◽

Xin-Tian Zhang ◽

...

Keyword(s):

Epithelial Cells ◽

Inflammatory Responses ◽

Intestinal Epithelial Cells ◽

High Mobility ◽

Protozoan Parasite ◽

Opportunistic Pathogen ◽

Intestinal Epithelial ◽

Content Type ◽

Effector Molecules ◽

Host Immune Responses

ABSTRACTCryptosporidium, a protozoan parasite that infects the gastrointestinal epithelium and other mucosal surfaces in humans and animals, is an important opportunistic pathogen in AIDS patients and one of the most common enteric pathogens affecting young children in developing regions. This parasite is referred to as a “minimally invasive” mucosal pathogen, and epithelial cells play a central role in activating and orchestrating host immune responses. We previously demonstrated thatCryptosporidium parvuminfection stimulates host epithelial cells to release exosomes, and these released exosomes shuttle several antimicrobial peptides to carry out anti-C. parvumactivity. In this study, we detected the upregulation of inflammatory genes in the liver and spleen followingC. parvumintestinal infection in neonatal mice. Interestingly, exosomes released from intestinal epithelial cells followingC. parvuminfection could activate the nuclear factor kappa B signaling pathway and trigger inflammatory gene transcription in isolated primary splenocytes. Several epithelial cell-derived proteins and a subset of parasite RNAs were detected in the exosomes released fromC. parvum-infected intestinal epithelial cells. Shuttling of these effector molecules, including the high mobility group box 1 protein, was involved in the induction of inflammatory responses in splenocytes induced by the exosomes released from infected cells. Our data indicate that exosomes released from intestinal epithelial cells uponC. parvuminfection can activate immune cells by shuttling various effector molecules, a process that may be relevant to host systemic responses toCryptosporidiuminfection.

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Intestinal Epithelial Cells Exposed to Bacteroides fragilis Enterotoxin Regulate NF-κB Activation and Inflammatory Responses through β-Catenin Expression

Infection and Immunity ◽

10.1128/iai.00312-19 ◽

2019 ◽

Vol 87 (11) ◽

Cited By ~ 4

Author(s):

Jong Ik Jeon ◽

Su Hyuk Ko ◽

Jung Mogg Kim

Keyword(s):

Epithelial Cells ◽

Inflammatory Responses ◽

Intestinal Epithelial Cells ◽

Glycogen Synthase ◽

Bacteroides Fragilis ◽

Mucosal Inflammation ◽

Activator Protein 1 ◽

Intestinal Epithelial ◽

Content Type ◽

Iκb Kinase

ABSTRACT The Bacteroides fragilis enterotoxin (BFT), a virulence factor of enterotoxigenic B. fragilis (ETBF), interacts with intestinal epithelial cells and can provoke signals that induce mucosal inflammation. Although β-catenin signaling is reported to be associated with inflammatory responses and BFT is known to cleave E-cadherin linked with β-catenin, little is known about the β-catenin-mediated regulation of inflammation in ETBF infection. This study was conducted to investigate the role of β-catenin as a cellular signaling intermediate in the induction of proinflammatory responses to stimulation of intestinal epithelial cells with BFT. Expression of β-catenin in intestinal epithelial cells was reduced relatively early after stimulation with BFT and then recovered to normal levels relatively late after stimulation. In contrast, phosphorylation of β-catenin in BFT-exposed cells occurred at high levels early in stimulation and decreased as time passed. Concurrently, late after stimulation the nuclear levels of β-catenin were relatively higher than those early after stimulation. Suppression of β-catenin resulted in increased NF-κB activity and interleukin-8 (IL-8) expression in BFT-stimulated cells. However, suppression or enhancement of β-catenin expression neither altered the phosphorylated IκB kinase α/β complex nor activated activator protein 1 signals. Furthermore, inhibition of glycogen synthase kinase 3β was associated with increased β-catenin expression and attenuated NF-κB activity and IL-8 expression in BFT-exposed cells. These findings suggest the negative regulation of NF-κB-mediated inflammatory responses by β-catenin in intestinal epithelial cells stimulated with BFT, resulting in attenuation of acute inflammation in ETBF infection.

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JunD Represses Transcription and Translation of the Tight Junction Protein Zona Occludens-1 Modulating Intestinal Epithelial Barrier Function

Molecular Biology of the Cell ◽

10.1091/mbc.e08-02-0175 ◽

2008 ◽

Vol 19 (9) ◽

pp. 3701-3712 ◽

Cited By ~ 45

Author(s):

Jie Chen ◽

Lan Xiao ◽

Jaladanki N. Rao ◽

Tongtong Zou ◽

Lan Liu ◽

...

Keyword(s):

Epithelial Cells ◽

Tight Junction ◽

Barrier Function ◽

Intestinal Epithelial Cells ◽

Binding Protein ◽

Mrna Translation ◽

Epithelial Barrier ◽

Intestinal Epithelial ◽

Intestinal Epithelial Barrier ◽

Epithelial Barrier Function

The AP-1 transcription factor JunD is highly expressed in intestinal epithelial cells, but its exact role in maintaining the integrity of intestinal epithelial barrier remains unknown. The tight junction (TJ) protein zonula occludens (ZO)-1 links the intracellular domain of TJ-transmembrane proteins occludin, claudins, and junctional adhesion molecules to many cytoplasmic proteins and the actin cytoskeleton and is crucial for assembly of the TJ complex. Here, we show that JunD negatively regulates expression of ZO-1 and is implicated in the regulation of intestinal epithelial barrier function. Increased JunD levels by ectopic overexpression of the junD gene or by depleting cellular polyamines repressed ZO-1 expression and increased epithelial paracellular permeability. JunD regulated ZO-1 expression at the levels of transcription and translation. Transcriptional repression of ZO-1 by JunD was mediated through cAMP response element-binding protein-binding site within its proximal region of the ZO-1-promoter, whereas induced JunD inhibited ZO-1 mRNA translation by enhancing the interaction of the ZO-1 3′-untranslated region with RNA-binding protein T cell-restricted intracellular antigen 1-related protein. These results indicate that JunD is a biological suppressor of ZO-1 expression in intestinal epithelial cells and plays a critical role in maintaining epithelial barrier function.

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Transcriptional regulation of importin-α1 by JunD modulates subcellular localization of RNA-binding protein HuR in intestinal epithelial cells

AJP Cell Physiology ◽

10.1152/ajpcell.00209.2016 ◽

2016 ◽

Vol 311 (6) ◽

pp. C874-C883 ◽

Cited By ~ 2

Author(s):

Yan Xu ◽

Jie Chen ◽

Lan Xiao ◽

Hee Kyoung Chung ◽

Yuan Zhang ◽

...

Keyword(s):

Epithelial Cells ◽

Subcellular Localization ◽

Rna Binding ◽

Nuclear Translocation ◽

Intestinal Epithelial Cells ◽

Binding Protein ◽

Rna Binding Protein ◽

Intestinal Epithelial ◽

Mucosal Regeneration ◽

Importin Α

The RNA-binding protein HuR is crucial for normal intestinal mucosal regeneration by modulating the stability and translation of target mRNAs, but the exact mechanism underlying HuR trafficking between the cytoplasm and nucleus remains largely unknown. Here we report a novel function of transcription factor JunD in the regulation of HuR subcellular localization through the control of importin-α1 expression in intestinal epithelial cells (IECs). Ectopically expressed JunD specifically inhibited importin-α1 at the transcription level, and this repression is mediated via interaction with CREB-binding site that was located at the proximal region of importin-α1 promoter. Reduction in the levels of importin-α1 by JunD increased cytoplasmic levels of HuR, although it failed to alter whole cell HuR levels. Increased levels of endogenous JunD by depleting cellular polyamines also inhibited importin-α1 expression and increased cytoplasmic HuR levels, whereas JunD silencing rescued importin-α1 expression and enhanced HuR nuclear translocation in polyamine-deficient cells. Moreover, importin-α1 silencing protected IECs against apoptosis, which was prevented by HuR silencing. These results indicate that JunD regulates HuR subcellular distribution by downregulating importin-α1, thus contributing to the maintenance of gut epithelium homeostasis.

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Study on effect of anti-diarrheal medicinal plants on enteropathogenic Escherichia coli induced interleukin-8 secretion by intestinal epithelial cells

Alternative Medicine Studies ◽

10.4081/ams.2011.e16 ◽

2011 ◽

Vol 1 (1) ◽

pp. 16 ◽

Cited By ~ 3

Author(s):

S. Brijesh ◽

Pundarikakshudu Tetali ◽

Tannaz J. Birdi

Keyword(s):

Escherichia Coli ◽

Epithelial Cells ◽

Medicinal Plants ◽

Inflammatory Responses ◽

Intestinal Epithelial Cells ◽

Colon Adenocarcinoma ◽

Cyperus Rotundus ◽

Health Concern ◽

Intestinal Epithelial ◽

Infantile Diarrhea

Diarrhea is a major health concern in developing countries with enteropathogenic Escherichia coli (EPEC) being a leading cause of infantile diarrhea. Much of the pathology of EPEC infection is due to the inflammatory responses of infected intestinal epithelium through secretion of pro-inflammatory cytoki - nes such as interleukin (IL)-8. With medicinal plants gaining popularity as prospective antidiarrheal agents, we aimed to evaluate the effect of anti-diarrheal medicinal plants on secretion of IL-8 by epithelial cells in response to EPEC infection. The effect of the decoctions of four anti-diarrheal medicinal plants viz. Aegle marmelos, Cyperus rotundus, Psidium guajava and Zingiber officinale was studied on secretion of IL-8 by a human colon adenocarcinoma cell line, HT-29 infected with E. coli E2348/69. Two protocols were used viz. pre-incubation and post-incubation. The data obtained demonstrated that out of the four plants used, only P. guajava decreased secretion of IL-8 in the post-incubation protocol although in the pre-incubation protocol an increase was observed. A similar increase was seen with C. rotundus in the preincubation protocol. No effect on IL-8 secretion was observed with A. marmelos and Z. officinale in both protocols and with C. rotundus in the post-incubation protocol. The post-incubation protocol, in terms of clinical relevance, indicates the effect of the plant decoctions when used as treatment. Hence P. guajava may be effective in controlling the acute inflammatory response of the intestinal epithelial cells in response to EPEC infection.

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