scholarly journals Strain-Dependent Induction of Enterocyte Apoptosis by Giardia lamblia Disrupts Epithelial Barrier Function in a Caspase-3-Dependent Manner

2002 ◽  
Vol 70 (7) ◽  
pp. 3673-3680 ◽  
Author(s):  
Alex C. Chin ◽  
Desiree A. Teoh ◽  
Kevin G.-E. Scott ◽  
Jonathon B. Meddings ◽  
Wallace K. Macnaughton ◽  
...  
Keyword(s):  
Barrier Function ◽  
Giardia Lamblia ◽  
Caspase 3 ◽  
Cytoskeletal Proteins ◽  
Epithelial Barrier ◽  
Dependent Manner ◽  
Epithelial Permeability ◽  
Epithelial Barrier Function ◽  
Enterocyte Apoptosis ◽  
Strain Dependent

ABSTRACT We recently demonstrated that Giardia lamblia rearranges cytoskeletal proteins and reduces transepithelial electrical resistance. The effect of G. lamblia on enterocyte apoptosis is unknown, and a possible link between microbially induced enterocyte apoptosis and altered epithelial permeability has yet to be established. The aim of this study was to assess whether G. lamblia induces enterocyte apoptosis in duodenal epithelial monolayers and whether this effect increases epithelial permeability. Monolayers of nontransformed human duodenal epithelial cells were incubated with sonicated or live G. lamblia trophozoites (NF, S2, WB, or PB strains) for 8, 24, and 48 h. Cell cultures were assessed for apoptosis by Hoechst fluorescence staining, enzyme-linked immunosorbent assay for apoptotic nucleosomes, and electron microscopy. In separate experiments, monolayers were pretreated with or without 120 μM caspase-3 inhibitor (Z-DEVD-FMK) for 1 h and were assessed for production of apoptotic nucleosomes, tight junctional integrity (with fluorescent ZO-1 staining followed by confocal laser microscopy), and transepithelial permeability for fluorescein isothiocyanate-dextran. G. lamblia strains NF and S2, but not strains WB or PB, induced enterocyte apoptosis within the monolayers, and this effect was inhibited by Z-DEVD-FMK pretreatment. Using the G. lamblia NF isolate, additional experiments investigated the possible link between enterocyte apoptosis and altered epithelial permeability. G. lamblia NF disrupted tight junctional ZO-1 and increased epithelial permeability, but these effects were also prevented by pretreatment with the caspase-3 inhibitor. These findings indicate that strain-dependent induction of enterocyte apoptosis may contribute to the pathogenesis of giardiasis. This effect is responsible for a loss of epithelial barrier function by disrupting tight junctional ZO-1 and increasing permeability in a caspase-3-dependent manner.

scholarly journals Lubiprostone Induces Claudin-1 and Protects Intestinal Barrier Function

Pharmacology ◽  
2019 ◽  
Vol 105 (1-2) ◽  
pp. 102-108 ◽  
Author(s):  
Norio Nishii ◽  
Tadayuki Oshima ◽  
Min Li ◽  
Hirotsugu Eda ◽  
Kumiko Nakamura ◽  
...  
Keyword(s):  
Barrier Function ◽  
Intestinal Barrier ◽  
Fluorescein Isothiocyanate ◽  
Intestinal Barrier Function ◽  
Epithelial Barrier ◽  
Dependent Manner ◽  
Epithelial Permeability ◽  
Epithelial Barrier Function ◽  
Dose Dependent

Introduction: Lubiprostone, a chloride channel activator, is said to reduce epithelial permeability. However, whether lubiprostone has a direct effect on the epithelial barrier function and how it modulates the intestinal barrier function remain unknown. Therefore, the effects of lubiprostone on intestinal barrier function were evaluated in vitro. Methods: Caco-2 cells were used to assess the intestinal barrier function. To examine the expression of claudins, immunoblotting was performed with specific antibodies. The effects of lubiprostone on cytokines (IFNγ, IL-6, and IL-1β) and aspirin-induced epithelial barrier disruption were assessed by transepithelial electrical resistance (TEER) and fluorescein isothiocyanate (FITC) labeled-dextran permeability. Results: IFNγ, IL-6, IL-1β, and aspirin significantly decreased TEER and increased epithelial permeability. Lubiprostone significantly improved the IFNγ-induced decrease in TEER in a dose-dependent manner. Lubiprostone significantly reduced the IFNγ-induced increase in FITC labeled-dextran permeability. The changes induced by IL-6, IL-1β, and aspirin were not affected by lubiprostone. The expression of claudin-1, but not claudin-3, claudin-4, occludin, and ZO-1 was significantly increased by lubiprostone. Conclusion: Lubiprostone significantly improved the IFNγ-induced decrease in TEER and increase in FITC labeled-dextran permeability. Lubiprostone increased the expression of claudin-1, and this increase may be related to the effect of lubiprostone on the epithelial barrier function.

scholarly journals Strain-Dependent Induction of Human Enterocyte Apoptosis byBlastocystisDisrupts Epithelial Barrier and ZO-1 Organization in a Caspase 3- and 9-Dependent Manner

2014 ◽  
Vol 2014 ◽  
pp. 1-11 ◽  
Author(s):  
Zhaona Wu ◽  
Haris Mirza ◽  
Joshua D. W. Teo ◽  
Kevin S. W. Tan
Keyword(s):  
Cytoskeletal Proteins ◽  
Epithelial Barrier ◽  
Epithelial Cell Line ◽  
Dependent Manner ◽  
Intestinal Epithelial ◽  
Human Intestine ◽  
Intestinal Epithelial Barrier ◽  
Epithelial Barrier Function ◽  
Enterocyte Apoptosis ◽  
Human Enterocyte

Blastocystisis an emerging protistan parasite colonizing the human intestine. It is frequently reported to cause general intestinal symptoms of vomiting, diarrhea, and abdominal pain. We recently demonstrated thatBlastocystisrearranged cytoskeletal proteins and induced intestinal epithelial barrier compromise. The effect ofBlastocystison enterocyte apoptosis is unknown, and a possible link between microbially induced enterocyte apoptosis and increased epithelial permeability has yet to be determined. The aim of this study is to assess ifBlastocystisinduces human enterocyte apoptosis and whether this effect influences human intestinal epithelial barrier function. Monolayers of polarized human colonic epithelial cell-line Caco-2 were incubated withBlastocystissubtype 7 and subtype 4. Assays for both early and late markers of apoptosis, phosphatidylserine externalization, and nuclear fragmentation, respectively, showed thatBlastocystisST-7, but not ST-4, significantly increased apoptosis in enterocytes, suggesting thatBlastocystisexhibits host specificity and strain-to-strain variation in pathogenicity. ST-7 also activated Caco-2 caspases 3 and 9 but not 8. ST-7 induced changes in epithelial resistance, permeability, and tight junction (ZO-1) localization. Pretreatment of Caco-2 monolayers with a pan-caspase inhibitor z-VAD-fmk significantly inhibited these changes. This suggests a role for enterocyte apoptosis inBlastocystis-mediated epithelial barrier compromise in the human intestine.

Abstract 616: Interleukin 22 Downregulates ABCG1 and Impairs Cholesterol Efflux in Macrophages

2014 ◽  
Vol 34 (suppl_1) ◽  
Author(s):  
Marion Hofmann Bowman ◽  
Bijoy Chellan ◽  
Ling Yan ◽  
Timothy Sonntag ◽  
Catherine Reardon
Keyword(s):  
Protein Expression ◽  
Barrier Function ◽  
Cholesterol Efflux ◽  
Peritoneal Macrophages ◽  
Mouse Serum ◽  
Epithelial Barrier ◽  
Dependent Manner ◽  
Epithelial Barrier Function ◽  
Cholesterol Uptake ◽  
Mrna And Protein Expression

IL22 belongs to the IL10 cytokine family and is expressed by T helper cells. IL22 functions on epithelial cells and has been shown to improve epithelial barrier function in inflammatory bowel disease, asthma, and psoriasis; autoimmune diseases associated with elevated serum IL22. Patients with psoriasis have increased coronary artery disease and it was previously shown that macrophages from patients with psoriasis have impaired cholesterol efflux. The function of IL-22 on macrophage cholesterol metabolism is not known. Methods: ABCA1, ABCG1 and CD36 mRNA and protein expression, cholesterol uptake and efflux were studied in murine macrophages and human THP-1 macrophages. C57BL6/J mice with transgenic expression of hS100A12 and hS100A8/9 in myeloid cells were generated by using a bacterial artificial chromosome (hBAC/S100 mice). hBAC/S100 and WT littermate mice were breed into mice lacking the receptor for advanced glycation endproducts, RAGE. Results: Peritoneal macrophages from hBAC/S100 mice have reduced ABCG1 mRNA and protein expression, increased cholesterol uptake, and reduced cholesterol efflux compared to WT. This was abolished in hBAC/S100 mice lacking RAGE, the receptor for S100/calgranulin. Recombinant S100A12 or S100A8 protein (2.5 μg/ml) had no effect on ABCG1 expression in WT peritoneal macrophages or human THP-1 cells, suggesting other systemic intermediary products in hBAC/S100 mice. Serum IL22 and mRNA in splenic T cells were significantly increased in hBAC/S100 mice, and this was abolished in hBAC/S100 mice lacking RAGE. Moreover, r S100A12 increased IL22 mRNA by 2-fold in cultured human THP-1. Importantly, THP-1 macrophages treated with r IL22 (100 ng/ml) had reduced expression of ABCG1 and impaired cholesterol efflux to mouse serum, but not to Apoa1. Up regulation of ABCG1 and ABCA1 in response to LXR agonist TO901317 in THP-1 cells abolished the detrimental effects of IL22 on cholesterol efflux. Conclusion: S100/calgranulin induces IL22 in a RAGE dependent manner. IL22 down regulates ABCG1 and impairs cholesterol efflux in macrophages. This raises the hypothesis that IL22-mediated down regulation of cellular cholesterol efflux may be linked to improved epithelial barrier function, but may also augment atherosclerosis.

Decreased epithelial barrier function evoked by exposure to metabolic stress and nonpathogenic E. coli is enhanced by TNF-α

2008 ◽  
Vol 294 (3) ◽  
pp. G669-G678 ◽  
Author(s):  
Kimberley Lewis ◽  
Jackie Caldwell ◽  
Van Phan ◽  
David Prescott ◽  
Aisha Nazli ◽  
...  
Keyword(s):  
Cell Line ◽  
Barrier Function ◽  
Metabolic Stress ◽  
Epithelial Barrier ◽  
Pyrrolidine Dithiocarbamate ◽  
Epithelial Permeability ◽  
Epithelial Barrier Function ◽  
E Coli ◽  
Tnf Α ◽  
The Impact

A defect in mitochondrial activity contributes to many diseases. We have shown that monolayers of the human colonic T84 epithelial cell line exposed to dinitrophenol (DNP, uncouples oxidative phosphorylation) and nonpathogenic Escherichia coli ( E. coli) (strain HB101) display decreased barrier function. Here the impact of DNP on macrophage activity and the effect of TNF-α, DNP, and E. coli on epithelial permeability were assessed. DNP treatment of the human THP-1 macrophage cell line resulted in reduced ATP synthesis, and, although hyporesponsive to LPS, the metabolically stressed macrophages produced IL-1β, IL-6, and TNF-α. Given the role of TNF-α in inflammatory bowel disease (IBD) and the association between increased permeability and IBD, recombinant TNF-α (10 ng/ml) was added to the DNP (0.1 mM) + E. coli (106 colony-forming units), and this resulted in a significantly greater loss of T84 epithelial barrier function than that elicited by DNP + E. coli. This increased epithelial permeability was not due to epithelial death, and the enhanced E. coli translocation was reduced by pharmacological inhibitors of NF-κβ signaling (pyrrolidine dithiocarbamate, NF-κβ essential modifier-binding peptide, BAY 11–7082, and the proteosome inhibitor, MG132). In contrast, the drop in transepithelial electrical resistance was unaffected by the inhibitors of NF-κβ. Thus, as an integrative model system, our findings support the induction of a positive feedback loop that can severely impair epithelial barrier function and, as such, could contribute to existing inflammation or trigger relapses in IBD. Thus metabolically stressed epithelia display increased permeability in the presence of viable nonpathogenic E. coli that is exaggerated by TNF-α released by activated immune cells, such as macrophages, that retain this ability even if they themselves are experiencing a degree of metabolic stress.

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