The Motogenic Effects of Cyclic Mechanical Strain on Intestinal Epithelial Monolayer Wound Closure Are Matrix Dependent

This article describes a model of reversible disassembly of a cultured human intestinal epithelial monolayer by prolonged exposure to the phorbol ester 12-O-tetradecanoylphorbol 13-acetate (TPA). Prolonged phorbol ester exposure reduces protein kinase C (PKC) levels in numerous cell types including T84, as shown here. Under PKC-downregulated conditions, T84 monolayers, which simulate the highly organized structure of native intestinal crypt cells, become disassembled into 2 or 3 layers of rounded cells. Proliferation does not account for these morphological changes as assessed by thymidine incorporation studies. The effects of structural disorganization on epithelial barrier function was also examined. The permeability of disassembled monolayers was significantly greater than that of controls. Flux studies localized the permeability defect to the tight junction. PKC-associated alterations in the perijunctional ring of actin and myosin, one of the putative regulators of flow across the tight junction, were found to correlate with the observed functional changes. Most interesting was the fact that monolayer reassembly to the original columnar epithelial phenotype and reestablishment of barrier function occurred upon normalization of PKC levels. This model of reversible monolayer disassembly will allow investigation into the relationship between epithelial structure and function and examination of factors that govern monolayer formation.

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Intestinal mucosal barrier dysfunction in SAP patients with MODS ameliorated by continuous blood purification

The International Journal of Artificial Organs ◽

10.5301/ijao.5000644 ◽

2017 ◽

Vol 41 (1) ◽

pp. 43-51

Author(s):

Qing Shen ◽

Zhengrong Li ◽

Shanshan Huang ◽

Liman Li ◽

Hua Gan ◽

...

Keyword(s):

Mrna Expression ◽

Mucosal Barrier ◽

Intestinal Epithelial ◽

Barrier Dysfunction ◽

Intestinal Mucosal Barrier ◽

Epithelial Monolayer ◽

Tnf Α ◽

Monolayer Permeability ◽

Α Level ◽

Junction Proteins

Background: Dysfunction of the intestinal mucosal barrier plays an important role in the pathophysiology of severe acute pancreatitis (SAP). Continuous blood purification (CBP) has been shown to improve the prognosis of SAP patients. In order to investigate the effect of CBP on intestinal mucosal barrier dysfunction in SAP patients with MODS, we conducted in vivo and in vitro experiments to explore the underlying mechanisms. Methods: The markers for the assessment of intestinal mucosal barrier function including serum diamine oxidase (DAO), endotoxin and intestinal epithelial monolayer permeability were detected during CBP therapy. The distribution and expression of cytoskeleton protein F-actin and tight junction proteins claudin-1 were observed. In addition, Rho kinase (ROCK) mRNA expression and serum tumor necrosis factor-alpha (TNF-α) levels during CBP were determined. Results: SAP patients with MODS had increased levels of serum DAO, endotoxin and intestinal epithelial monolayer permeability when compared with normal controls. While the distribution of F-actin and claudin-1 was rearranged, and the expression of claudin-1 significantly decreased, but F-actin had no change. Meanwhile, ROCK mRNA expression and serum TNF-α level were increased. However, after CBP treatment, levels of serum DAO, endotoxin and intestinal epithelial monolayer permeability decreased. The F-actin and claudin-1 reorganization attenuated and the expression of claudin-1 increased. At the same time, ROCK mRNA expression and serum TNF-α level were decreased. Conclusions: CBP can effectively improve intestinal mucosal barrier dysfunction. The beneficial effect is associated with the improvement of cytoskeleton and tight junction proteins in stability by downregulation of ROCK mRNA expression through the removal of excess proinflammatory factors.

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Effect of Ciprofloxacin on Shiga Toxin Production and Translocation across an Intestinal Epithelial Monolayer

Pediatric Research ◽

10.1203/00006450-199904020-00971 ◽

1999 ◽

Vol 45 (4, Part 2 of 2) ◽

pp. 163A-163A

Author(s):

Jenifer L Jaeger ◽

David Acheson

Keyword(s):

Shiga Toxin ◽

Toxin Production ◽

Intestinal Epithelial ◽

Epithelial Monolayer

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Annexin 2 Regulates Intestinal Epithelial Cell Spreading and Wound Closure through Rho-Related Signaling

American Journal Of Pathology ◽

10.2353/ajpath.2007.060647 ◽

2007 ◽

Vol 170 (3) ◽

pp. 951-966 ◽

Cited By ~ 59

Author(s):

Brian A. Babbin ◽

Charles A. Parkos ◽

Kenneth J. Mandell ◽

L. Matthew Winfree ◽

Oskar Laur ◽

...

Keyword(s):

Epithelial Cell ◽

Intestinal Epithelial Cell ◽

Wound Closure ◽

Cell Spreading ◽

Intestinal Epithelial ◽

Annexin 2

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Murine Norovirus Transcytosis across anIn VitroPolarized Murine Intestinal Epithelial Monolayer Is Mediated by M-Like Cells

Journal of Virology ◽

10.1128/jvi.02378-13 ◽

2013 ◽

Vol 87 (23) ◽

pp. 12685-12693 ◽

Cited By ~ 31

Author(s):

Mariam B. Gonzalez-Hernandez ◽

Thomas Liu ◽

Luz P. Blanco ◽

Heather Auble ◽

Hilary C. Payne ◽

...

Keyword(s):

Viral Entry ◽

Cell Monolayer ◽

Small Animal ◽

Intestinal Epithelial ◽

Murine Norovirus ◽

Small Animal Model ◽

Intestinal Epithelial Barrier ◽

M Cell ◽

Epithelial Monolayer

Noroviruses (NoVs) are the causative agent of the vast majority of nonbacterial gastroenteritis worldwide. Due to the inability to culture human NoVs and the inability to orally infect a small animal model, little is known about the initial steps of viral entry. One particular step that is not understood is how NoVs breach the intestinal epithelial barrier. Murine NoV (MNV) is the only NoV that can be propagatedin vitroby infecting murine macrophages and dendritic cells, making this virus an attractive model for studies of different aspects of NoV biology. Polarized murine intestinal epithelial mICcl2cells were used to investigate how MNV interacts with and crosses the intestinal epithelium. In thisin vitromodel of the follicle-associated epithelium (FAE), MNV is transported across the polarized cell monolayer in the absence of viral replication or disruption of tight junctions by a distinct epithelial cell with microfold (M) cell properties. In addition to transporting MNV, these M-like cells also transcytose microbeads and express an IgA receptor. Interestingly, B myeloma cells cultured in the basolateral compartment underlying the epithelial monolayer did not alter the number of M-like cells but increased their transcytotic activity. Our data demonstrate that MNV can cross an intact intestinal epithelial monolayerin vitroby hijacking the M-like cells' intrinsic transcytotic pathway and suggest a potential mechanism for MNV entry into the host.

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Pharmacological HIF-1 stabilization promotes intestinal epithelial healing through regulation of α-integrin expression and function

AJP Gastrointestinal and Liver Physiology ◽

10.1152/ajpgi.00192.2020 ◽

2021 ◽

Author(s):

Bridie Jane Goggins ◽

Kyra Minahan ◽

Simonne Sherwin ◽

Wai S Soh ◽

Jennifer Pryor ◽

...

Keyword(s):

Wound Closure ◽

Hypoxia Inducible Factor ◽

Mucosal Healing ◽

Integrin Expression ◽

Intestinal Epithelial ◽

Epithelial Migration ◽

Gene And Protein Expression ◽

Integrin Α2 ◽

Epithelial Healing

Intestinal epithelia are critical for maintaining gastrointestinal homeostasis. Epithelial barrier injury, causing inflammation and vascular damage, results in inflammatory hypoxia and thus healing occurs in an oxygen-restricted environment. The transcription factor hypoxia inducible factor (HIF)-1 regulates genes important for cell survival and repair, including the cell adhesion protein β1-integrin. Integrins function as αβ-dimers and α-integrin-matrix binding is critical for cell migration. We hypothesized that HIF-1 stabilization accelerates epithelial migration through integrin-dependent pathways. We aimed to examine functional and post-translational activity of α-integrins during HIF-1-mediated intestinal epithelial healing. Wound healing was assessed in T84 monolayers over 24 hours with/without prolyl-hydroxylase inhibitor (PHDi) (GB-004), which stabilizes HIF-1. Gene and protein expression were measured by RT-PCR and immunoblot, α-integrin localization was assessed by immunofluorescence. α-integrin function was assessed by antibody-mediated blockade and integrin-α6 regulation was determined by HIF-1α chromatin immunoprecipitation. Models of mucosal wounding and TNBS-induced colitis were used to examine integrin expression and localization in vivo. PHDi-treatment accelerated wound closure and migration within 12 hours, associated with increased integrin-α2 and α6 protein, but not α3. Functional blockade of integrins-α2 and α6 inhibited PHDi-mediated accelerated wound closure. HIF-1 bound directly to the integrin-α6 promoter. PHDi treatment accelerated mucosal healing, which was associated with increased α6 immunohistochemical staining in wound-associated epithelium and wound-adjacent tissue. PHDi-treatment increased α6 protein levels in colonocytes of TNBS mice and induced α6 staining in regenerating crypts and re-epithelialized inflammatory lesions. Together these data demonstrate a role for HIF-1 in regulating both integrin-α2 and α6 responses during intestinal epithelial healing.

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Mathematical modeling of airway epithelial wound closure during cyclic mechanical strain

Journal of Applied Physiology ◽

10.1152/japplphysiol.00510.2003 ◽

2004 ◽

Vol 96 (2) ◽

pp. 566-574 ◽

Cited By ~ 55

Author(s):

Ushma Savla ◽

Lars E. Olson ◽

Christopher M. Waters

Keyword(s):

Cell Density ◽

Wound Closure ◽

Numerical Solutions ◽

Airway Epithelial Cell ◽

Mechanical Strain ◽

Cyclic Strain ◽

Airway Epithelial Cells ◽

Airway Epithelial ◽

Model Equations ◽

Different Sources

The repair of airway epithelium after injury is crucial in restoring epithelial barrier integrity. Because the airways are stretched and compressed due to changes in both circumferential and longitudinal dimensions during respiration and may be overdistended during mechanical ventilation, we investigated the effect of cyclic strain on the repair of epithelial wounds. Both cyclic elongation and compression significantly slowed repair, with compression having the greatest effect. We developed a mathematical model of the mechanisms involved in airway epithelial cell wound closure. The model focuses on the differences in spreading, migration, and proliferation with cyclic strain by using separate parameters for each process and incorporating a time delay for the mitotic component. Numerical solutions of model equations determine the shape of the diffusive wave solutions of cell density that correspond to the influx of cells into the wound during the initial phase of reepithelialization. Model simulations were compared with experimental measurements of cell density and the rate of wound closure, and parameters were determined based on measurements from airway epithelial cells from several different sources. The contributions of spreading, migration, and mitosis were investigated both numerically and experimentally by using cytochalasin D to inhibit cell motility and mitomycin C to inhibit proliferation.

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