scholarly journals Zinc ameliorates intestinal barrier dysfunctions in shigellosis by reinstating claudin-2 and -4 on the membranes

2019 ◽  
Vol 316 (2) ◽  
pp. G229-G246 ◽  
Author(s):  
Paramita Sarkar ◽  
Tultul Saha ◽  
Irshad Ali Sheikh ◽  
Subhra Chakraborty ◽  
Joydeep Aoun ◽  
...  
Keyword(s):  
Inflammatory Response ◽  
Tight Junction ◽  
Barrier Function ◽  
Intracellular Signaling ◽  
Ion Selectivity ◽  
Intestinal Lumen ◽  
Mouse Tissue ◽  
Barrier Dysfunction ◽  
Intracellular Location ◽  
Junction Protein

Whether zinc (Zn2+) regulates barrier functions by modulating tight-junction (TJ) proteins when pathogens such as Shigella alter epithelial permeability is still unresolved. We investigated the potential benefits of Zn2+ in restoring impaired barrier function in vivo in Shigella-infected mouse tissue and in vitro in T84 cell monolayers. Basolateral Shigella infection triggered a time-dependent decrease in transepithelial resistance followed by an increase in paracellular permeability of FITC-labeled dextran and altered ion selectivity. This led to ion and water loss into the intestinal lumen. Immunofluorescence studies revealed redistribution of claudin-2 and -4 to an intracellular location and accumulation of these proteins in the cytoplasm following infection. Zn2+ ameliorated this perturbed barrier by redistribution of claudin-2 and -4 back to the plasma membrane and by modulating the phosphorylation state of TJ proteins t hough extracellular signal-regulated kinase (ERK)1/2 dependency. Zn2+ prevents elevation of IL-6 and IL-8. Mice challenged with Shigella showed that oral Zn2+supplementation diminished diverse pathophysiological symptoms of shigellosis. Claudin-2 and -4 were susceptible to Shigella infection, resulting in altered barrier function and increased levels of IL-6 and IL-8. Zn2+ supplementation ameliorated this barrier dysfunction, and the inflammatory response involving ERK-mediated change of phosphorylation status for claudin-2 and -4. Thus, Zn2+ may have potential therapeutic value in inflammatory diarrhea and shigellosis. NEW & NOTEWORTHY Our study addresses whether Zn2+ could be an alternative strategy to reduce Shigella-induced inflammatory response and epithelial barrier dysfunction. We have defined a mechanism in terms of intracellular signaling pathways and tight-junction protein expression by Zn2+. Claudin-2 and -4 are susceptible to Shigella infection, whereas in the presence of Zn2+ they are resistant to infection-related barrier dysfunction involving ERK-mediated change of phosphorylation status of claudins.

scholarly journals Myosin light chain kinase mediates intestinal barrier dysfunction via occludin endocytosis during anoxia/reoxygenation injury

2016 ◽  
Vol 311 (6) ◽  
pp. C996-C1004 ◽  
Author(s):  
Younggeon Jin ◽  
Anthony T. Blikslager
Keyword(s):  
Tight Junction ◽  
Light Chain ◽  
Barrier Function ◽  
Myosin Light Chain Kinase ◽  
Myosin Light Chain ◽  
Ischemia Reperfusion Injury ◽  
Ischemia Reperfusion ◽  
Barrier Dysfunction ◽  
Junction Protein ◽  
Mlc Phosphorylation

Intestinal anoxia/reoxygenation (A/R) injury induces loss of barrier function followed by epithelial repair. Myosin light chain kinase (MLCK) has been shown to alter barrier function via regulation of interepithelial tight junctions, but has not been studied in intestinal A/R injury. We hypothesized that A/R injury would disrupt tight junction barrier function via MLCK activation and myosin light chain (MLC) phosphorylation. Caco-2BBe1 monolayers were subjected to anoxia for 2 h followed by reoxygenation in 21% O2, after which barrier function was determined by measuring transepithelial electrical resistance (TER) and FITC-dextran flux. Tight junction proteins and MLCK signaling were assessed by Western blotting, real-time PCR, or immunofluorescence microscopy. The role of MLCK was further investigated with select inhibitors (ML-7 and peptide 18) by using in vitro and ex vivo models. Following A/R injury, there was a significant increase in paracellular permeability compared with control cells, as determined by TER and dextran fluxes ( P < 0.05). The tight junction protein occludin was internalized during A/R injury and relocalized to the region of the tight junction after 4 h of recovery. MLC phosphorylation was significantly increased by A/R injury ( P < 0.05), and treatment with the MLCK inhibitor peptide 18 attenuated the increased epithelial monolayer permeability and occludin endocytosis caused by A/R injury. Application of MLCK inhibitors to ischemia-injured porcine ileal mucosa induced significant increases in TER and reduced mucosal-to-serosal fluxes of3H-labeled mannitol. These data suggest that MLCK-induced occludin endocytosis mediates intestinal epithelial barrier dysfunction during A/R injury. Our results also indicate that MLCK-dependent occludin regulation may be a target for the therapeutic treatment of ischemia/reperfusion injury.

scholarly journals Occludin S408 phosphorylation regulates tight junction protein interactions and barrier function

2011 ◽  
Vol 193 (3) ◽  
pp. 565-582 ◽  
Author(s):  
David R. Raleigh ◽  
Devin M. Boe ◽  
Dan Yu ◽  
Christopher R. Weber ◽  
Amanda M. Marchiando ◽  
...  
Keyword(s):  
Tight Junction ◽  
Dynamic Behavior ◽  
Protein Interactions ◽  
Protein Complex ◽  
Barrier Function ◽  
Therapeutic Potential ◽  
Paracellular Permeability ◽  
Tight Junction Protein ◽  
Barrier Dysfunction ◽  
Junction Protein

Although the C-terminal cytoplasmic tail of the tight junction protein occludin is heavily phosphorylated, the functional impact of most individual sites is undefined. Here, we show that inhibition of CK2-mediated occludin S408 phosphorylation elevates transepithelial resistance by reducing paracellular cation flux. This regulation requires occludin, claudin-1, claudin-2, and ZO-1. S408 dephosphorylation reduces occludin exchange, but increases exchange of ZO-1, claudin-1, and claudin-2, thereby causing the mobile fractions of these proteins to converge. Claudin-4 exchange is not affected. ZO-1 domains that mediate interactions with occludin and claudins are required for increases in claudin-2 exchange, suggesting assembly of a phosphorylation-sensitive protein complex. Consistent with this, binding of claudin-1 and claudin-2, but not claudin-4, to S408A occludin tail is increased relative to S408D. Finally, CK2 inhibition reversed IL-13–induced, claudin-2–dependent barrier loss. Thus, occludin S408 dephosphorylation regulates paracellular permeability by remodeling tight junction protein dynamic behavior and intermolecular interactions between occludin, ZO-1, and select claudins, and may have therapeutic potential in inflammation-associated barrier dysfunction.

Glucocorticoids regulate barrier function and claudin expression in intestinal epithelial cells via MKP-1

2014 ◽  
Vol 306 (3) ◽  
pp. G218-G228 ◽  
Author(s):  
Andreas Fischer ◽  
Markus Gluth ◽  
Friderike Weege ◽  
Ulrich-Frank Pape ◽  
Bertram Wiedenmann ◽  
...  
Keyword(s):  
Tight Junction ◽  
Barrier Function ◽  
Collagenous Colitis ◽  
Dependent Manner ◽  
Intestinal Epithelial ◽  
Barrier Dysfunction ◽  
Junction Protein ◽  
Bowel Diseases ◽  
Vitro Model

Barrier dysfunction is pivotal to the pathogenesis of inflammatory bowel diseases (IBD) and collagenous colitis. Glucocorticoids restore barrier function in Crohn's disease, but whether this reflects attenuated inflammation or an epithelial-specific action has not yet been addressed. Using filter-grown Caco-2 monolayers as an in vitro model of the intestinal epithelial barrier, we observed that glucocorticoids induced a time- and dose-dependent increase in transepithelial electrical resistance (TEER) in a glucocorticoid receptor-dependent manner without altering flux of larger solutes or changing principal tight junction architecture. This was accompanied by reduced paracellular cation flux, reduced expression of the pore-forming tight junction component claudin-2, and upregulation of the sealing tight junction protein claudin-4. In contrast, expression of occludin, claudin-1, -7, or -8 was not altered. Dexamethasone increased expression and activity of MAPK phosphatase-1 and inhibition of this phosphatase prevented the glucocorticoid-induced changes in TEER and claudin expression, whereas inhibiting p38 or MEK1/2 was not sufficient to replicate the glucocorticoid effects. Upon exposure to IFN-γ, TNF-α, or IL-1β, TEERs declined in dexamethasone-treated cells but remained consistently higher than in cells not receiving glucocorticoids. Treatment with IFN/TNF resulted in an upregulation of claudin-2 that was significantly attenuated by dexamethasone, whereas increased claudin-2 expression upon IL-1β stimulation was not affected by glucocorticoids. Taken together, barrier augmentation might represent a previously unrecognized mechanism of action, potentially contributing to the therapeutic efficacy of glucocorticoids in IBD and collagenous colitis.

scholarly journals Impacts of Fructose on Intestinal Barrier Function, Inflammation and Microbiota in a Piglet Model

Nutrients ◽  
2021 ◽  
Vol 13 (10) ◽  
pp. 3515
Author(s):  
Pingting Guo ◽  
Haichao Wang ◽  
Linbao Ji ◽  
Peixia Song ◽  
Xi Ma
Keyword(s):  
Inflammatory Response ◽  
Tight Junction ◽  
Growth Performance ◽  
Oxidant Stress ◽  
Intestinal Barrier ◽  
Sensu Stricto ◽  
Intestinal Barrier Function ◽  
Human Beings ◽  
Barrier Dysfunction ◽  
Gene Expressions

The metabolic disorder caused by excessive fructose intake was reported extensively and often accompanied by intestinal barrier dysfunction. And the rising dietary fructose was consumed at an early age of human. However, related researches were almost conducted in rodent models, while in the anatomy and physiology of gastrointestinal tract, pig is more similar to human beings than rodents. Hence, weaned piglets were chosen as the model animals in our study to investigate the fructose’s impacts on intestinal tight junction, inflammation response and microbiota structure of piglets. Herein, growth performance, inflammatory response, oxidation resistance and ileal and colonic microbiota of piglet were detected after 35-day fructose supplementation. Our results showed decreased tight junction gene expressions in piglets after fructose addition, with no obvious changes in the growth performance, antioxidant resistance and inflammatory response. Moreover, fructose supplementation differently modified the microbiota structures in ileum and colon. In ileum, the proportions of Streptococcus and Faecalibacterium were higher in Fru group (fructose supplementation). In colon, the proportions of Blautia and Clostridium sensu stricto 1 were higher in Fru group. All the results suggested that tight junction dysfunction might be an earlier fructose-induced event than inflammatory response and oxidant stress and that altered microbes in ileum and colon might be the potential candidates to alleviate fructose-induced intestinal permeability alteration.

scholarly journals Acidic Bile Salt Modulates the Squamous Epithelial Barrier Function by Modulating Tight Junction Protein

2011 ◽  
Vol 140 (5) ◽  
pp. S-619-S-620
Author(s):  
Xin Chen ◽  
Tadayuki Oshima ◽  
Toshihiko Tomita ◽  
Hirokazu Fukui ◽  
Jiro Watari ◽  
...  
Keyword(s):  
Tight Junction ◽  
Bile Salt ◽  
Barrier Function ◽  
Tight Junction Protein ◽  
Epithelial Barrier ◽  
Epithelial Barrier Function ◽  
Junction Protein

scholarly journals Role of JAM-A tyrosine phosphorylation in epithelial barrier dysfunction during intestinal inflammation

2019 ◽  
Vol 30 (5) ◽  
pp. 566-578 ◽  
Author(s):  
Shuling Fan ◽  
Caroline M. Weight ◽  
Anny-Claude Luissint ◽  
Roland S. Hilgarth ◽  
Jennifer C. Brazil ◽  
...  
Keyword(s):  
Tyrosine Phosphorylation ◽  
Barrier Function ◽  
Intestinal Inflammation ◽  
Kinase Inhibitor ◽  
Src Kinase ◽  
Small Gtpase ◽  
Epithelial Barrier ◽  
Barrier Dysfunction ◽  
Junction Protein

Junctional adhesion molecule-A (JAM-A), an epithelial tight junction protein, plays an important role in regulating intestinal permeability through association with a scaffold signaling complex containing ZO-2, Afadin, and the small GTPase Rap2. Under inflammatory conditions, we report that the cytoplasmic tail of JAM-A is tyrosine phosphorylated (p-Y280) in association with loss of barrier function. While barely detectable Y280 phosphorylation was observed in confluent monolayers of human intestinal epithelial cells under basal conditions, exposure to cytokines TNFα, IFNγ, IL-22, or IL-17A, resulted in compromised barrier function in parallel with increased p-Y280. Phosphorylation was Src kinase dependent, and we identified Yes-1 and PTPN13 as a major kinase and phosphatase for p-JAM-A Y280, respectively. Moreover, cytokines IL-22 or IL-17A induced increased activity of Yes-1. Furthermore, the Src kinase inhibitor PP2 rescued cytokine-induced epithelial barrier defects and inhibited phosphorylation of JAM-A Y280 in vitro. Phosphorylation of JAM-A Y280 and increased permeability correlated with reduced JAM-A association with active Rap2. Finally, we observed increased phosphorylation of Y280 in colonic epithelium of individuals with ulcerative colitis and in mice with experimentally induced colitis. These findings support a novel mechanism by which tyrosine phosphorylation of JAM-A Y280 regulates epithelial barrier function during inflammation.

scholarly journals The role of zinc deficiency in alcohol-induced intestinal barrier dysfunction

2010 ◽  
Vol 298 (5) ◽  
pp. G625-G633 ◽  
Author(s):  
Wei Zhong ◽  
Craig J. McClain ◽  
Matthew Cave ◽  
Y. James Kang ◽  
Zhanxiang Zhou
Keyword(s):  
Oxidative Stress ◽  
Tight Junction ◽  
Zinc Deficiency ◽  
Barrier Function ◽  
Intestinal Barrier ◽  
Alcohol Exposure ◽  
Epithelial Barrier ◽  
Tight Junction Proteins ◽  
Barrier Dysfunction ◽  
Junction Proteins

Disruption of the intestinal barrier is a causal factor in the development of alcoholic endotoxemia and hepatitis. This study was undertaken to determine whether zinc deficiency is related to the deleterious effects of alcohol on the intestinal barrier. Mice were pair fed an alcohol or isocaloric liquid diet for 4 wk, and hepatitis was detected in association with elevated blood endotoxin level. Alcohol exposure significantly increased the permeability of the ileum but did not affect the barrier function of the duodenum or jejunum. Reduction of tight-junction proteins at the ileal epithelium was detected in alcohol-fed mice although alcohol exposure did not cause apparent histopathological changes. Alcohol exposure significantly reduced the ileal zinc concentration in association with accumulation of reactive oxygen species. Caco-2 cell culture demonstrated that alcohol exposure increases the intracellular free zinc because of oxidative stress. Zinc deprivation caused epithelial barrier disruption in association with disassembling of tight junction proteins in the Caco-2 monolayer cells. Furthermore, minor zinc deprivation exaggerated the deleterious effect of alcohol on the epithelial barrier. In conclusion, epithelial barrier dysfunction in the distal small intestine plays an important role in alcohol-induced gut leakiness, and zinc deficiency attributable to oxidative stress may interfere with the intestinal barrier function by a direct action on tight junction proteins or by sensitizing to the effects of alcohol.

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