The role of caspase-3 in lipopolysaccharide-mediated disruption of intestinal epithelial tight junctions

2006 ◽  
Vol 84 (10) ◽  
pp. 1043-1050 ◽  
Author(s):  
Alex C. Chin ◽  
Andrew N. Flynn ◽  
Jason P. Fedwick ◽  
Andre G. Buret
Keyword(s):  
Escherichia Coli ◽  
Tight Junctions ◽  
Intestinal Permeability ◽  
Barrier Function ◽  
Caspase 3 ◽  
Parp Cleavage ◽  
Intestinal Epithelial ◽  
Epithelial Permeability ◽  
Epithelial Monolayers

The mechanisms responsible for microbially induced epithelial apoptosis and increased intestinal permeability remain unclear. This study assessed whether purified bacterial lipopolysaccharide (LPS) increases epithelial apoptosis and permeability and whether these changes are dependent on caspase-3 activation. In nontumorigenic epithelial monolayers, Escherichia coli O26:B6 LPS increased apoptosis, as shown by nuclear breakdown, caspase-3 activation, and PARP cleavage, and induced disruption of tight junctional ZO-1. Apical, but not basolateral, exposure to LPS increased epithelial permeability. Addition of a caspase-3 inhibitor abolished the effects of LPS. The findings describe a novel mechanism whereby apical LPS may disrupt epithelial tight junctional ZO-1 and barrier function in a caspase-3-dependent fashion.

scholarly journals Potential Regulatory Effects of Corticotropin-Releasing Factor on Tight Junction-Related Intestinal Epithelial Permeability are Partially Mediated by CK8 Upregulation

2017 ◽  
Vol 44 (3) ◽  
pp. 1161-1173 ◽  
Author(s):  
Hu Yue ◽  
Lu  Bin ◽  
Chen Chaoying ◽  
Zhang Meng ◽  
Li Meng ◽  
...  
Keyword(s):  
Tight Junction ◽  
Tight Junctions ◽  
Intestinal Permeability ◽  
Corticotropin Releasing Factor ◽  
Intestinal Epithelial ◽  
Epithelial Permeability ◽  
Expression Levels ◽  
Rhoa Activity ◽  
Junction Protein ◽  
Regulatory Effects

Background/Aims: Intestinal permeability and stress have been implicated in the pathophysiology of irritable bowel syndrome (IBS). Cytokeratin 8 (CK8), for the first time, has been shown to mediate corticotropin-releasing factor (CRF)-induced changes in intestinal permeability in animal models of IBS. In this study, we investigated the regulatory effects of CRF on the permeability of human intestinal epithelial cells through the CK8-mediated tight junction. Methods: The expression levels of corticotropin-releasing factor receptor 1 (CRFR1) and corticotropin-releasing factor receptor 2 (CRFR2) on the HT29 cell surface were determined by immunofluorescence, RT-PCR, and Western blotting. After treatment with 100 nM CRF for 72 h, the translocation of FITC-labelled dextran was measured in a transwell chamber; the structural changes of tight junctions were observed under transmission electron microscopy; the expression levels of CK8, F-actin and tight junction proteins ZO-1, claudin-1, and occludin were detected by immunoblotting and immunofluorescence. The activity of RhoA was detected by immunoprecipitation. Furthermore, the effects of CRF on intestinal epithelial permeability were examined in CK8-silenced HT29 cells, which were constructed by shRNA interference. Results: CRF treatment increased FITC-labelled dextran permeability, caused the opening of tight junctions, induced increased fluorescence intensity of CK8 and decreased the intensities of ZO-1, claudin-1, and occludin, together with structural disruption. The expression levels of F-actin, occludin, claudin-1, and ZO-1 were downregulated. RhoA activity peaked at 30 min after CRF treatment. CRF-induced increased permeability, and downregulation of claudin-1 and occludin were not blocked by CK8 silencing. Nevertheless, CK8 silencing blocked the effects of CRF regarding the decrease in the expression levels of F-action and ZO-1 and increase in RhoA activity. Conclusion: CRF may increase intestinal epithelial permeability by upregulating CK8 expression, activating the RhoA signalling pathway, promoting intestinal epithelial actin remodelling, and decreasing the expression of the tight junction protein ZO-1. Other CK8-independent pathways may be involved in the downregulation of claudin-1 and occludin, which might also contribute to increased intestinal epithelial permeability.

Zonulin and Its Regulation of Intestinal Barrier Function: The Biological Door to Inflammation, Autoimmunity, and Cancer

2011 ◽  
Vol 91 (1) ◽  
pp. 151-175 ◽  
Author(s):  
Alessio Fasano
Keyword(s):  
Gastrointestinal Tract ◽  
Tight Junctions ◽  
Barrier Function ◽  
Intestinal Barrier ◽  
Intestinal Barrier Function ◽  
Intestinal Epithelial ◽  
New Paradigm ◽  
Intestinal Epithelial Barrier ◽  
Neoplastic Disorders

The primary functions of the gastrointestinal tract have traditionally been perceived to be limited to the digestion and absorption of nutrients and to electrolytes and water homeostasis. A more attentive analysis of the anatomic and functional arrangement of the gastrointestinal tract, however, suggests that another extremely important function of this organ is its ability to regulate the trafficking of macromolecules between the environment and the host through a barrier mechanism. Together with the gut-associated lymphoid tissue and the neuroendocrine network, the intestinal epithelial barrier, with its intercellular tight junctions, controls the equilibrium between tolerance and immunity to non-self antigens. Zonulin is the only physiological modulator of intercellular tight junctions described so far that is involved in trafficking of macromolecules and, therefore, in tolerance/immune response balance. When the finely tuned zonulin pathway is deregulated in genetically susceptible individuals, both intestinal and extraintestinal autoimmune, inflammatory, and neoplastic disorders can occur. This new paradigm subverts traditional theories underlying the development of these diseases and suggests that these processes can be arrested if the interplay between genes and environmental triggers is prevented by reestablishing the zonulin-dependent intestinal barrier function. This review is timely given the increased interest in the role of a “leaky gut” in the pathogenesis of several pathological conditions targeting both the intestine and extraintestinal organs.

scholarly journals STAT3 Signalling via the IL-6ST/gp130 Cytokine Receptor Promotes Epithelial Integrity and Intestinal Barrier Function during DSS-Induced Colitis

Biomedicines ◽  
2021 ◽  
Vol 9 (2) ◽  
pp. 187
Author(s):  
Lokman Pang ◽  
Jennifer Huynh ◽  
Mariah G. Alorro ◽  
Xia Li ◽  
Matthias Ernst ◽  
...  
Keyword(s):  
Barrier Function ◽  
Intestinal Barrier ◽  
Intestinal Barrier Function ◽  
Intestinal Epithelial ◽  
Barrier Dysfunction ◽  
Epithelial Integrity ◽  
Barrier Integrity ◽  
Gp130 Receptor ◽  
Stat3 Signalling

The intestinal epithelium provides a barrier against commensal and pathogenic microorganisms. Barrier dysfunction promotes chronic inflammation, which can drive the pathogenesis of inflammatory bowel disease (IBD) and colorectal cancer (CRC). Although the Signal Transducer and Activator of Transcription-3 (STAT3) is overexpressed in both intestinal epithelial cells and immune cells in IBD patients, the role of the interleukin (IL)-6 family of cytokines through the shared IL-6ST/gp130 receptor and its associated STAT3 signalling in intestinal barrier integrity is unclear. We therefore investigated the role of STAT3 in retaining epithelial barrier integrity using dextran sulfate sodium (DSS)-induced colitis in two genetically modified mouse models, to either reduce STAT1/3 activation in response to IL-6 family cytokines with a truncated gp130∆STAT allele (GP130∆STAT/+), or by inducing short hairpin-mediated knockdown of Stat3 (shStat3). Here, we show that mice with reduced STAT3 activity are highly susceptible to DSS-induced colitis. Mechanistically, the IL-6/gp130/STAT3 signalling cascade orchestrates intestinal barrier function by modulating cytokine secretion and promoting epithelial integrity to maintain a defence against bacteria. Our study also identifies a crucial role of STAT3 in controlling intestinal permeability through tight junction proteins. Thus, therapeutically targeting the IL-6/gp130/STAT3 signalling axis to promote barrier function may serve as a treatment strategy for IBD patients.

Enteropathogenic Escherichia coli adherence to intestinal epithelial monolayers diminishes barrier function

1995 ◽  
Vol 268 (2) ◽  
pp. G374-G379 ◽  
Author(s):  
J. Spitz ◽  
R. Yuhan ◽  
A. Koutsouris ◽  
C. Blatt ◽  
J. Alverdy ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Host Cell ◽  
Barrier Function ◽  
Cell Function ◽  
Cytoskeletal Proteins ◽  
Calcium Stores ◽  
Intestinal Epithelial ◽  
Enteropathogenic Escherichia Coli ◽  
Wild Type ◽  
Cell Monolayers

The mechanism by which enteropathogenic Escherichia coli (EPEC) causes diarrhea remains elusive. Several alterations within the host cell have been demonstrated to occur following EPEC attachment including increases in intracellular Ca2+ concentration and rearrangement and phosphorylation of several cytoskeletal proteins. The consequences of these intracellular perturbations on host cell function, however, have not been determined. The aim of this study was to examine the effect of EPEC adherence on intestinal epithelial barrier function. T84 cell monolayers were infected with either wild-type EPEC or a nonadherent isogenic derivative. Transepithelial electrical resistance, a measure of barrier function, decreased 33.5 +/- 6.4% after a 6-h incubation with the wild-type strain. Electron microscopy revealed ultrastructurally normal cells, and lactate dehydrogenase release assays failed to demonstrate cytotoxicity. Dual 22Na+ and [3H]mannitol flux studies localized the permeability defect to tight junctions. In addition, cumulative flux of the paracellular marker mannitol was four- to fivefold greater across monolayers infected with wild-type EPEC. Sequestration of intracellular calcium stores by dantrolene completely abrogated the resistance drop associated with EPEC attachment. These data demonstrate that adherence of EPEC to intestinal epithelial cell monolayers disrupts tight junction barrier function via a calcium-requiring event.

The role of protein kinase C isozymes in TNF-α-induced cytotoxicity to a rat intestinal epithelial cell line

2001 ◽  
Vol 280 (4) ◽  
pp. G572-G583 ◽  
Author(s):  
Q. Chang ◽  
B. L. Tepperman
Keyword(s):  
Epithelial Cell ◽  
Caspase 3 ◽  
Cell Injury ◽  
Cell Damage ◽  
Epithelial Cell Line ◽  
Intestinal Epithelial ◽  
Kinase C ◽  
Pkc Isoforms ◽  
Tnf Α

Tumor necrosis factor (TNF)-α can induce cytotoxicity and apoptosis in a number of cell types and has been implicated in the regulation of many inflammatory processes. It has been suggested that protein kinase C (PKC) is one of the intracellular mediators of the actions of TNF-α. In the present study, the role of PKC isoforms in TNF-α-mediated cytotoxicity and apoptosis in intestinal cells was investigated using the rat epithelial cell line, IEC-18. Cells were incubated with TNF-α in the presence or absence of the transcription inhibitor actinomycin D (AMD). The extent of cell damage was enhanced when AMD was added to incubation medium, suggesting that new protein synthesis plays a role in the cytotoxic action of TNF. TNF-α also induced the translocation of PKC-α, -δ, and -ε from cytosol to the membrane fraction of the intestinal cells. Furthermore, the cytotoxic and apoptotic effects of TNF were reduced by pretreating the cells with the PKC-ε translocation inhibitor, PKC-εV1–2. In contrast, although cells incubated with the phorbol ester phorbol 12-myristate 13-acetate (PMA) also displayed an increase in cell injury, the extent of cytotoxicity and apoptosis was not enhanced by AMD. Furthermore, PMA-induced cell damage was reduced by rottlerin, a PKC-δ inhibitor. Caspase-3, an enzyme implicated in the mediation of apoptosis, was activated in cells in response to either TNF-α or PMA stimulation, and its effects on this activity were reduced by selective inhibition of PKC-ε and -δ, respectively. Furthermore, inhibition of caspase-3 activity reduced apoptosis. These data suggest that activation of selective PKC isoforms mediate the effects of TNF-α on intestinal epithelial cell injury.

PGE2promotes Ca2+-mediated epithelial barrier disruption through EP1and EP4receptors in Caco-2 cell monolayers

2010 ◽  
Vol 299 (2) ◽  
pp. C324-C334 ◽  
Author(s):  
M. José Rodríguez-Lagunas ◽  
Raquel Martín-Venegas ◽  
Juan José Moreno ◽  
Ruth Ferrer
Keyword(s):  
Signaling Pathways ◽  
Barrier Function ◽  
Epithelial Barrier ◽  
Intestinal Epithelial ◽  
Epithelial Barrier Function ◽  
Cell Monolayers ◽  
Intracellular Ca ◽  
Inflammatory Processes ◽  
Zona Occludens

We recently demonstrated that PGE2induces the disruption of the intestinal epithelial barrier function. In the present study, our objectives were to study the role of PGE2receptors (EP1–EP4) and the signaling pathways involved in this event. Paracellular permeability (PP) was assessed in differentiated Caco-2 cell cultures from d-mannitol fluxes and transepithelial electrical resistance (TER) in the presence of different PGE2receptor agonists (carbacyclin, sulprostone, butaprost, ONO-AE1-259, ONO-AE-248, GR63799, and ONO-AE1-329) and antagonists (ONO-8711, SC-19220, AH-6809, ONO-AE3-240, ONO-AE3-208, and AH-23848). The results indicate that EP1and EP4but not EP2and EP3might be involved in PP regulation. These effects were mediated through PLC-inositol trisphosphate (IP3)-Ca2+and cAMP-PKA signaling pathways, respectively. We also observed an increase in intracellular Ca2+concentration ([Ca2+]i) strengthened by cAMP formation indicating a cross talk interaction of these two pathways. Moreover, the participation of a conventional PKC isoform was shown. The results also indicate that the increase in PP may be correlated with the redistribution of occludin, zona occludens 1 (ZO-1), and the perijunctional actin ring together with an increase in myosin light chain kinase activity. Although the disruption of epithelial barrier function observed in inflammatory bowel disease (IBD) patients has been traditionally attributed to cytokines, the present study focused on the role of PGE2in PP regulation, as mucosal levels of this eicosanoid are also increased in these inflammatory processes.

scholarly journals Neurons and Glia in the Enteric Nervous System and Epithelial Barrier Function

Physiology ◽  
2018 ◽  
Vol 33 (4) ◽  
pp. 269-280 ◽  
Author(s):  
Nathalie Vergnolle ◽  
Carla Cirillo
Keyword(s):  
Nervous System ◽  
Enteric Nervous System ◽  
Barrier Function ◽  
Current Knowledge ◽  
The Body ◽  
Epithelial Barrier ◽  
Intestinal Epithelial ◽  
Epithelial Barrier Function ◽  
Exchange Surface

The intestinal epithelial barrier is the largest exchange surface between the body and the external environment. Its functions are regulated by luminal, and also internal, components including the enteric nervous system. This review summarizes current knowledge about the role of the digestive “neuronal-glial-epithelial unit” on epithelial barrier function.

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