scholarly journals The serine protease-mediated increase in intestinal epithelial barrier function is dependent on occludin and requires an intact tight junction

2016 ◽  
Vol 311 (3) ◽  
pp. G466-G479 ◽  
Author(s):  
Natalie J. Ronaghan ◽  
Judie Shang ◽  
Vadim Iablokov ◽  
Raza Zaheer ◽  
Pina Colarusso ◽  
...  
Keyword(s):  
Epithelial Cell ◽  
Tight Junction ◽  
Serine Protease ◽  
Barrier Function ◽  
Serine Proteases ◽  
Cell Fractionation ◽  
Intestinal Epithelial ◽  
Tight Junction Proteins ◽  
Junction Protein ◽  
Junction Proteins

Barrier dysfunction is a characteristic of the inflammatory bowel diseases (IBD), Crohn's disease and ulcerative colitis. Understanding how the tight junction is modified to maintain barrier function may provide avenues for treatment of IBD. We have previously shown that the apical addition of serine proteases to intestinal epithelial cell lines causes a rapid and sustained increase in transepithelial electrical resistance (TER), but the mechanisms are unknown. We hypothesized that serine proteases increase barrier function through trafficking and insertion of tight junction proteins into the membrane, and this could enhance recovery of a disrupted monolayer after calcium switch or cytokine treatment. In the canine epithelial cell line, SCBN, we showed that matriptase, an endogenous serine protease, could potently increase TER. Using detergent solubility-based cell fractionation, we found that neither trypsin nor matriptase treatment changed levels of tight junction proteins at the membrane. In a fast calcium switch assay, serine proteases did not enhance the rate of recovery of the junction. In addition, serine proteases could not reverse barrier disruption induced by IFNγ and TNFα. We knocked down occludin in our cells using siRNA and found this prevented the serine protease-induced increase in TER. Using fluorescence recovery after photobleaching (FRAP), we found serine proteases induce a greater mobile fraction of occludin in the membrane. These data suggest that a functional tight junction is needed for serine proteases to have an effect on TER, and that occludin is a crucial tight junction protein in this mechanism.

Digestion of epithelial tight junction proteins by the commensal Clostridium perfringens

2013 ◽  
Vol 305 (10) ◽  
pp. G740-G748 ◽  
Author(s):  
Mihaela Pruteanu ◽  
Fergus Shanahan
Keyword(s):  
Epithelial Cell ◽  
Tight Junction ◽  
Clostridium Perfringens ◽  
Culture Supernatant ◽  
Dependent Manner ◽  
Intestinal Epithelial ◽  
Tight Junction Proteins ◽  
Epithelial Tight Junction ◽  
Junction Proteins ◽  
E Cadherin

The enteric microbiota contributes to the pathogenesis of inflammatory bowel disease, but the pathways involved and bacterial participants may vary in different hosts. We previously reported that some components of the human commensal microbiota, particularly Clostridium perfringens ( C. perfringens), have the proteolytic capacity for host matrix degradation and reduce transepithelial resistance. Here, we examined the C. perfringens-derived proteolytic activity against epithelial tight junction proteins using human intestinal epithelial cell lines. We showed that the protein levels of E-cadherin, occludin, and junctional adhesion molecule 1 decrease in colonic cells treated with C. perfringens culture supernatant. E-cadherin ectodomain shedding in C. perfringens-stimulated intestinal epithelial cells was detected with antibodies against the extracellular domain of E-cadherin, and we demonstrate that this process occurs in a time- and dose-dependent manner. In addition, we showed that the filtered sterile culture supernatant of C. perfringens has no cytotoxic activity on the human intestinal cells at the concentrations used in this study. The direct cleavage of E-cadherin by the proteases from the C. perfringens culture supernatant was confirmed by C. perfringens supernatant-induced in vitro degradation of the human recombinant E-cadherin. We conclude that C. perfringens culture supernatant mediates digestion of epithelial cell junctional proteins, which is likely to enable access to the extracellular matrix components by the paracellular pathway.

Intestinal epithelial cell proliferation, apoptosis and expression of tight junction proteins in patients with obstructive jaundice

2010 ◽  
Vol 41 (2) ◽  
pp. 117-125 ◽  
Author(s):  
Stelios F. Assimakopoulos ◽  
Athanassios C. Tsamandas ◽  
Emanuel Louvros ◽  
Constantine E. Vagianos ◽  
Vassiliki N. Nikolopoulou ◽  
...  
Keyword(s):  
Cell Proliferation ◽  
Epithelial Cell ◽  
Obstructive Jaundice ◽  
Tight Junction ◽  
Intestinal Epithelial Cell ◽  
Intestinal Epithelial ◽  
Epithelial Cell Proliferation ◽  
Tight Junction Proteins ◽  
Junction Proteins

scholarly journals Intestinal epithelial barrier function and tight junction proteins with heat and exercise

2016 ◽  
Vol 120 (6) ◽  
pp. 692-701 ◽  
Author(s):  
Karol Dokladny ◽  
Micah N. Zuhl ◽  
Pope L. Moseley
Keyword(s):  
Heat Stress ◽  
Tight Junction ◽  
Barrier Function ◽  
Epithelial Barrier ◽  
Intestinal Epithelial ◽  
Tight Junction Proteins ◽  
Intestinal Epithelial Barrier ◽  
Epithelial Tight Junction ◽  
Junction Proteins

A single layer of enterocytes and tight junctions (intercellular multiprotein complexes) form the intestinal epithelial barrier that controls transport of molecules through transcellular and paracellular pathways. A dysfunctional or “leaky” intestinal tight junction barrier allows augmented permeation of luminal antigens, endotoxins, and bacteria into the blood stream. Various substances and conditions have been shown to affect the maintenance of the intestinal epithelial tight junction barrier. The primary focus of the present review is to analyze the effects of exertional or nonexertional (passive hyperthermia) heat stress on tight junction barrier function in in vitro and in vivo (animals and humans) models. Our secondary focus is to review changes in tight junction proteins in response to exercise or hyperthermic conditions. Finally, we discuss some pharmacological or nutritional interventions that may affect the cellular mechanisms involved in maintaining homeostasis of the intestinal epithelial tight junction barrier during heat stress or exercise.

scholarly journals Lactobacillus plantarum inhibits intestinal epithelial barrier dysfunction induced by unconjugated bilirubin

2010 ◽  
Vol 104 (3) ◽  
pp. 390-401 ◽  
Author(s):  
Yukun Zhou ◽  
Huanlong Qin ◽  
Ming Zhang ◽  
Tongyi Shen ◽  
Hongqi Chen ◽  
...  
Keyword(s):  
Tight Junction ◽  
Lactobacillus Plantarum ◽  
Laser Scanning Microscopy ◽  
Unconjugated Bilirubin ◽  
Epithelial Barrier ◽  
Intestinal Epithelial ◽  
Tight Junction Proteins ◽  
Intestinal Epithelial Barrier ◽  
Junction Protein ◽  
Junction Proteins

Although a large number of in vitro and in vivo tests have confirmed that taking probiotics can improve the intestinal barrier, few studies have focused on the relationship between probiotics and the intestinal epithelial barrier in hyperbilirubinaemia. To investigate the effects of and mechanisms associated with probiotic bacteria (Lactobacillus plantarum; LP) and unconjugated bilirubin (UCB) on the intestinal epithelial barrier, we measured the viability, apoptotic ratio and protein kinase C (PKC) activity of Caco-2 cells. We also determined the distribution and expression of tight junction proteins such as occludin, zonula occludens (ZO)-1, claudin-1, claudin-4, junctional adhesion molecule (JAM)-1 and F-actin using confocal laser scanning microscopy, immunohistochemistry, Western blotting and real-time quantitative PCR. The present study demonstrated that high concentrations of UCB caused obvious cytotoxicity and decreased the transepithelial electrical resistance (TER) of the Caco-2 cell monolayer. Low concentrations of UCB inhibited the expression of tight junction proteins and PKC but could induce UDP-glucuronosyltransferases 1 family-polypeptide A1 (UGT1A1) expression. UCB alone caused decreased PKC activity, serine phosphorylated occludin and ZO-1 levels. After treatment with LP, the effects of UCB on TER and apoptosis were mitigated; LP also prevented aberrant expression and rearrangement of tight junction proteins. Moreover, PKC activity and serine phosphorylated tight junction protein levels were partially restored after treatment with LP, LP exerted a protective effect against UCB damage to Caco-2 monolayer cells, and it restored the structure and distribution of tight junction proteins by activating the PKC pathway. In addition, UGT1A1 expression induced by UCB in Caco-2 cells could ameliorate the cytotoxicity of UCB.

Polyamines are necessary for synthesis and stability of occludin protein in intestinal epithelial cells

2005 ◽  
Vol 288 (6) ◽  
pp. G1159-G1169 ◽  
Author(s):  
Xin Guo ◽  
Jaladanki N. Rao ◽  
Lan Liu ◽  
Tongtong Zou ◽  
Kaspar M. Keledjian ◽  
...  
Keyword(s):  
Epithelial Cells ◽  
Tight Junction ◽  
Barrier Function ◽  
Intestinal Epithelial Cells ◽  
Integral Membrane Protein ◽  
Epithelial Barrier ◽  
Intestinal Epithelial ◽  
Tight Junction Proteins ◽  
Epithelial Barrier Function ◽  
Junction Proteins

Occludin is an integral membrane protein that forms the sealing element of tight junctions and is critical for epithelial barrier function. Polyamines are implicated in multiple signaling pathways driving different biological functions of intestinal epithelial cells (IEC). The present study determined whether polyamines are involved in expression of occludin and play a role in intestinal epithelial barrier function. Studies were conducted in stable Cdx2-transfected IEC-6 cells (IEC-Cdx2L1) associated with a highly differentiated phenotype. Polyamine depletion by α-difluoromethylornithine (DFMO) decreased levels of occludin protein but failed to affect expression of its mRNA. Other tight junction proteins, zonula occludens (ZO)-1, ZO-2, claudin-2, and claudin-3, were also decreased in polyamine-deficient cells. Decreased levels of tight junction proteins in DFMO-treated cells were associated with dysfunction of the epithelial barrier, which was overcome by exogenous polyamine spermidine. Decreased levels of occludin in polyamine-deficient cells was not due to the reduction of intracellular-free Ca2+ concentration ([Ca2+]cyt), because either increased or decreased [Ca2+]cyt did not alter levels of occludin in the presence or absence of polyamines. The level of newly synthesized occludin protein was decreased by ∼70% following polyamine depletion, whereas its protein half-life was reduced from ∼120 min in control cells to ∼75 min in polyamine-deficient cells. These findings indicate that polyamines are necessary for the synthesis and stability of occludin protein and that polyamine depletion disrupts the epithelial barrier function, at least partially, by decreasing occludin.

scholarly journals Eugenol attenuates inflammatory response and enhances barrier function during lipopolysaccharide-induced inflammation in the porcine intestinal epithelial cells

2020 ◽  
Vol 98 (8) ◽  
Author(s):  
Qianru Hui ◽  
Emily Ammeter ◽  
Shangxi Liu ◽  
Runqiang Yang ◽  
Peng Lu ◽  
...  
Keyword(s):  
Amino Acid ◽  
Tight Junction ◽  
Barrier Function ◽  
Inflammatory Responses ◽  
Intestinal Epithelial Cells ◽  
Mrna Abundance ◽  
Intestinal Epithelial ◽  
Tight Junction Proteins ◽  
Sodium Dependent ◽  
Junction Proteins

Abstract Eugenol (4-allyl-2-methoxyphenol) is an essential oil component, possessing antimicrobial, anti-inflammatory, and antioxidative properties; however, the effect of eugenol on porcine gut inflammation has not yet been investigated. In this study, an in vitro lipopolysaccharide (LPS)-induced inflammation model in porcine intestinal epithelial cells (IPEC-J2) has been set up. Cells were pretreated with 100 μM (16.42 mg/L) eugenol for 2 h followed by 10 μg/mL LPS stimulation for 6 h. Proinflammatory cytokine secretion; reactive oxygen species; gene expression of proinflammatory cytokines, tight junction proteins, and nutrient transporters; the expression and distribution of zonula occludens-1 (ZO-1); transepithelial electrical resistance (TEER); and cell permeability were measured to investigate the effect of eugenol on inflammatory responses and gut barrier function. The results showed that eugenol pretreatment significantly suppressed the LPS-stimulated interleukin-8 level and the mRNA abundance of tumor necrosis factor-α and restored the LPS-stimulated decrease of the mRNA abundance of tight junction proteins, such as ZO-1 and occludin, and the mRNA abundance of nutrient transporters, such as B0 1 system ASC sodium-dependent neutral amino acid exchanger 2, sodium-dependent glucose transporter 1, excitatory amino acid transporter 1, and peptide transporter 1. In addition, eugenol improved the expression and even redistribution of ZO-1 and tended to increase TEER value and maintained the barrier integrity. In conclusion, a low dose of eugenol attenuated inflammatory responses and enhanced selectively permeable barrier function during LPS-induced inflammation in the IPEC-J2 cell line.

Differential effects of EPA and DHA on DSS-induced colitis in mice and possible mechanisms involved

2021 ◽  
Author(s):  
Zhuangwei Zhang ◽  
Zhe Xue ◽  
Haitao Yang ◽  
Feng Zhao ◽  
Chundi Liu ◽  
...  
Keyword(s):  
Cell Proliferation ◽  
Epithelial Cell ◽  
Tight Junction ◽  
Signaling Pathways ◽  
Intestinal Epithelial Cell ◽  
Intestinal Epithelial ◽  
Epithelial Cell Proliferation ◽  
Tight Junction Proteins ◽  
Inflammatory Signaling ◽  
Junction Proteins

EPA, superior to DHA, significantly attenuated DSS-induced colitis involved in promoting the expression of tight junction proteins, suppressing inflammatory signaling pathways and triggering intestinal epithelial cell proliferation.

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