Mathematical modeling of airway epithelial wound closure during cyclic mechanical strain

2004 ◽  
Vol 96 (2) ◽  
pp. 566-574 ◽  
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.

Mechanical strain inhibits repair of airway epithelium in vitro

1998 ◽  
Vol 274 (6) ◽  
pp. L883-L892 ◽  
Author(s):  
Ushma Savla ◽  
Christopher M. Waters
Keyword(s):  
Airway Epithelium ◽  
Mechanical Strain ◽  
Radial Strain ◽  
Cyclic Strain ◽  
Airway Epithelial Cells ◽  
Significant Inhibition ◽  
Cell Area ◽  
Airway Epithelial ◽  
And Migration

The repair of airway epithelium after injury is crucial in restoring epithelial barrier integrity. Although the airway epithelium is stretched and compressed due to changes in both circumferential and longitudinal dimensions during respiration and may be overdistended during mechanical ventilation, the effect of cyclic strain on the repair of epithelial wounds is unknown. Human and cat airway epithelial cells were cultured on flexible membranes, wounded by scraping with a metal spatula, and subjected to cyclic strain using the Flexercell Strain Unit. Because the radial strain profile in the wells was nonuniform, we compared closure in regions of elongation and compression within the same well. Both cyclic elongation and cyclic compression significantly slowed repair, with compression having the greatest effect. This attenuation was dependent upon the time of relaxation (TR) during the cycle. When wells were stretched at 10 cycles/min (6 s/cycle) with TR = 5 s, wounds closed similarly to wounds in static wells, whereas in wells with TR = 1 s, significant inhibition was observed. As the TR during cycles increased (higher TR), wounds closed faster. We measured the effect of strain at various TRs on cell area and centroid-centroid distance (CD) as a measure of spreading and migration. While cell area and CD in static wells significantly increased over time, the area and CD of cells in the elongated regions did not change. Cells in compressed regions were significantly smaller, with significantly lower CD. Cell area and CD became progressively larger with increasing TR. These results suggest that mechanical strain inhibits epithelial repair.

scholarly journals FOXO3a regulates rhinovirus-induced innate immune responses in airway epithelial cells

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Joao Gimenes-Junior ◽  
Nicole Owuar ◽  
Hymavathi Reddy Vari ◽  
Wuyan Li ◽  
Nathaniel Xander ◽  
...  
Keyword(s):  
Epithelial Cell ◽  
Epithelial Cells ◽  
Lung Inflammation ◽  
Inflammatory Cytokine ◽  
Airway Epithelial Cell ◽  
Critical Role ◽  
Airway Epithelial Cells ◽  
Type I ◽  
Airway Epithelial ◽  
Antiviral Responses

AbstractForkhead transcription factor class O (FOXO)3a, which plays a critical role in a wide variety of cellular processes, was also found to regulate cell-type-specific antiviral responses. Airway epithelial cells express FOXO3a and play an important role in clearing rhinovirus (RV) by mounting antiviral type I and type III interferon (IFN) responses. To elucidate the role of FOXO3a in regulating antiviral responses, we generated airway epithelial cell-specific Foxo3a knockout (Scga1b1-Foxo3a−/−) mice and a stable FOXO3a knockout human airway epithelial cell line. Compared to wild-type, Scga1b1-Foxo3a−/− mice show reduced IFN-α, IFN-β, IFN-λ2/3 in response to challenge with RV or double-stranded (ds)RNA mimic, Poly Inosinic-polycytidylic acid (Poly I:C) indicating defective dsRNA receptor signaling. RV-infected Scga1b1-Foxo3a−/− mice also show viral persistence, enhanced lung inflammation and elevated pro-inflammatory cytokine levels. FOXO3a K/O airway epithelial cells show attenuated IFN responses to RV infection and this was associated with conformational change in mitochondrial antiviral signaling protein (MAVS) but not with a reduction in the expression of dsRNA receptors under unstimulated conditions. Pretreatment with MitoTEMPO, a mitochondrial-specific antioxidant corrects MAVS conformation and restores antiviral IFN responses to subsequent RV infection in FOXO3a K/O cells. Inhibition of oxidative stress also reduces pro-inflammatory cytokine responses to RV in FOXO3a K/O cells. Together, our results indicate that FOXO3a plays a critical role in regulating antiviral responses as well as limiting pro-inflammatory cytokine expression. Based on these results, we conclude that FOXO3a contributes to optimal viral clearance and prevents excessive lung inflammation following RV infection.

scholarly journals Agonist binding to β-adrenergic receptors on human airway epithelial cells inhibits migration and wound repair

2015 ◽  
Vol 309 (12) ◽  
pp. C847-C855 ◽  
Author(s):  
Elizabeth R. Peitzman ◽  
Nathan A. Zaidman ◽  
Peter J. Maniak ◽  
Scott M. O'Grady
Keyword(s):  
Epithelial Cells ◽  
Protein Phosphatase ◽  
Adrenergic Receptors ◽  
Wound Repair ◽  
Wound Closure ◽  
Basal Membrane ◽  
Airway Epithelial Cells ◽  
Airway Epithelial ◽  
Phosphatase 2A ◽  
Β Adrenergic Receptors

Human airway epithelial cells express β-adrenergic receptors (β-ARs), which regulate mucociliary clearance by stimulating transepithelial anion transport and ciliary beat frequency. Previous studies using airway epithelial cells showed that stimulation with isoproterenol increased cell migration and wound repair by a cAMP-dependent mechanism. In the present study, impedance-sensing arrays were used to measure cell migration and epithelial restitution following wounding of confluent normal human bronchial epithelial (NHBE) and Calu-3 cells by electroporation. Stimulation with epinephrine or the β2-AR-selective agonist salbutamol significantly delayed wound closure and reduced the mean surface area of lamellipodia protruding into the wound. Treatment with the β-AR bias agonist carvedilol or isoetharine also produced a delay in epithelial restitution similar in magnitude to epinephrine and salbutamol. Measurements of extracellular signal-regulated kinase phosphorylation following salbutamol or carvedilol stimulation showed no significant change in the level of phosphorylation compared with untreated control cells. However, inhibition of protein phosphatase 2A activity completely blocked the delay in wound closure produced by β-AR agonists. In Calu-3 cells, where CFTR expression was inhibited by RNAi, salbutamol did not inhibit wound repair, suggesting that β-AR agonist stimulation and loss of CFTR function share a common pathway leading to inhibition of epithelial repair. Confocal images of the basal membrane of Calu-3 cells labeled with anti-β1-integrin (clone HUTS-4) antibody showed that treatment with epinephrine or carvedilol reduced the level of activated integrin in the membrane. These findings suggest that treatment with β-AR agonists delays airway epithelial repair by a G protein- and cAMP-independent mechanism involving protein phosphatase 2A and a reduction in β1-integrin activation in the basal membrane.

scholarly journals Mechanical stretch decreases FAK phosphorylation and reduces cell migration through loss of JIP3-induced JNK phosphorylation in airway epithelial cells

2009 ◽  
Vol 297 (3) ◽  
pp. L520-L529 ◽  
Author(s):  
Leena P. Desai ◽  
Steven R. White ◽  
Christopher M. Waters
Keyword(s):  
Cell Migration ◽  
Epithelial Cells ◽  
Mechanical Strain ◽  
Mechanical Stretch ◽  
Inhibitory Effect ◽  
Airway Epithelial Cells ◽  
Airway Epithelial ◽  
Interacting Protein ◽  
Kinase Activation ◽  
Mapk Cascades

JNK is a nonreceptor kinase involved in the early events that signal cell migration after injury. However, the linkage to early signals required to initiate the migration response to JNK has not been defined in airway epithelial cells, which exist in an environment subjected to cyclic mechanical strain (MS). The present studies demonstrate that the JNK/stress-activated protein kinase-associated protein 1 (JSAP1; also termed JNK-interacting protein 3, JIP3), a scaffold factor for MAPK cascades that links JNK activation to focal adhesion kinase (FAK), are both associated and activated following mechanical injury in 16HBE14o− human airway epithelial cells and that both FAK and JIP3 phosphorylation seen after injury are decreased in cells subjected to cyclic MS. Overexpression of either wild-type (WT)-FAK or WT-JIP3 enhanced phosphorylation and kinase activation of JNK and reduced the inhibitory effect of cyclic MS. These results suggest that cyclic MS impairs signaling of cell migration after injury via a pathway that involves FAK-JIP3-JNK.

Effects of corticosteroid-induced apoptosis on airway epithelial wound closure in vitro

2006 ◽  
Vol 291 (4) ◽  
pp. L794-L801 ◽  
Author(s):  
Delbert R. Dorscheid ◽  
Benjamin J. Patchell ◽  
Oscar Estrada ◽  
Bertha Marroquin ◽  
Roberta Tse ◽  
...  
Keyword(s):  
Cell Migration ◽  
Epithelial Cell ◽  
Epithelial Cells ◽  
Untreated Control ◽  
Wound Closure ◽  
Airway Epithelial Cell ◽  
Airway Epithelial ◽  
Wound Area ◽  
Epithelial Cell Migration

Damage to the airway epithelium is common in asthma. Corticosteroids induce apoptosis in and suppress proliferation of airway epithelial cells in culture. Whether apoptosis contributes to impaired epithelial cell repair after injury is not known. We examined whether corticosteroids would impair epithelial cell migration in an in vitro model of wound closure. Wounds (∼0.5–1.3 mm2) were created in cultured 1HAEo−human airway epithelial cell monolayers, after which cells were treated with up to 10 μM dexamethasone or budesonide for 24 h. Cultured cells were pretreated for 24 or 48 h with dexamethasone to observe the effect of long-term exposure on wound closure. After 12 h, the remaining wound area in monolayers pretreated for 48 h with 10 μM dexamethasone was 43 ± 18% vs. 10 ± 8% for untreated control monolayers. The addition of either corticosteroid immediately after injury did not slow closure significantly. After 12 h the remaining wound area in monolayers treated with 10 μM budesonide was 39 ± 4% vs. 43 ± 3% for untreated control monolayers. The proportion of apoptotic epithelial cells as measured by terminal deoxynucleotidyltransferase-mediated dUTP biotin nick end labeling both at and away from the wound edge was higher in monolayers treated with budesonide compared with controls. However, wound closure in the apoptosis-resistant 1HAEo−.Bcl-2+cell line was not different after dexamethasone treatment. We demonstrate that corticosteroid treatment before mechanical wounding impairs airway epithelial cell migration. The addition of corticosteroids after injury does not slow migration, despite their ability to induce apoptosis in these cells.

A system to impose prescribed homogenous strains on cultured cells

2001 ◽  
Vol 91 (4) ◽  
pp. 1600-1610 ◽  
Author(s):  
Christopher M. Waters ◽  
Matthew R. Glucksberg ◽  
Eugene P. Lautenschlager ◽  
Chyh-Woei Lee ◽  
Reed M. Van Matre ◽  
...  
Keyword(s):  
Epithelial Cells ◽  
Cultured Cells ◽  
Large Strain ◽  
Mechanical Strain ◽  
Airway Epithelial Cells ◽  
Airway Epithelial ◽  
Degree Of Anisotropy ◽  
High Degree ◽  
Membrane Shape ◽  
First Time

There is presently significant interest in cellular responses to physical forces, and numerous devices have been developed to apply stretch to cultured cells. Many of the early devices were limited by the heterogeneity of deformation of cells in different locations and by the high degree of anisotropy at a particular location. We have therefore developed a system to impose cyclic, large-strain, homogeneous stretch on a multiwell surface-treated silicone elastomer substrate plated with pulmonary epithelial cells. The pneumatically driven mechanism consists of four plates each with a clamp to fix one edge of the cruciform elastomer substrate. Four linear bearings set at predetermined angles between the plates ensure a constant ratio of principal strains throughout the stretch cycle. We present the design of the device and membrane shape, the surface modifications of the membrane to promote cell adhesion, predicted and experimental measurements of the strain field, and new data using cultured airway epithelial cells. We present for the first time the relationship between the magnitude of cyclic mechanical strain and the extent of wound closure and cell spreading.

Paraoxonase-2 deficiency enhancesPseudomonas aeruginosaquorum sensing in murine tracheal epithelia

2007 ◽  
Vol 292 (4) ◽  
pp. L852-L860 ◽  
Author(s):  
David A. Stoltz ◽  
Egon A. Ozer ◽  
Carey J. Ng ◽  
Janet M. Yu ◽  
Srinivasa T. Reddy ◽  
...  
Keyword(s):  
Epithelial Cell ◽  
Epithelial Cells ◽  
Quorum Sensing ◽  
Airway Epithelial Cell ◽  
Airway Epithelial Cells ◽  
Airway Epithelial ◽  
Airway Epithelia ◽  
Tracheal Epithelial Cells ◽  
Human Airway ◽  
Tracheal Epithelial

Pseudomonas aeruginosa is an important cause of nosocomial infections and is frequently present in the airways of cystic fibrosis patients. Quorum sensing mediates P. aeruginosa's virulence and biofilm formation through density-dependent interbacterial signaling with autoinducers. N-3-oxododecanoyl homoserine lactone (3OC12-HSL) is the major autoinducer in P. aeruginosa. We have previously shown that human airway epithelia and paraoxonases (PONs) degrade 3OC12-HSL. This study investigated the role of PON1, PON2, and PON3 in airway epithelial cell inactivation of 3OC12-HSL. All three PONs were present in murine tracheal epithelial cells, with PON2 and PON3 expressed at the highest levels. Lysates of tracheal epithelial cells from PON2, but not PON1 or PON3, knockout mice had impaired 3OC12-HSL inactivation compared with wild-type mice. In contrast, PON1-, PON2-, or PON3-targeted deletions did not affect 3OC12-HSL degradation by intact epithelia. Overexpression of PON2 enhanced 3OC12-HSL degradation by human airway epithelial cell lysates but not by intact epithelia. Finally, using a quorum-sensing reporter strain of P. aeruginosa, we found that quorum sensing was enhanced in PON2-deficient airway epithelia. In summary, these results show that loss of PON2 impairs 3OC12-HSL degradation by airway epithelial cells and suggests that diffusion of 3OC12-HSL into the airway cells can be the rate-limiting step for degradation of the molecule.

Hog barn dust extract augments lymphocyte adhesion to human airway epithelial cells

2004 ◽  
Vol 96 (5) ◽  
pp. 1738-1744 ◽  
Author(s):  
T. Mathisen ◽  
S. G. Von Essen ◽  
T. A. Wyatt ◽  
D. J. Romberger
Keyword(s):  
Epithelial Cell ◽  
Epithelial Cells ◽  
Cell Function ◽  
Airway Epithelial Cell ◽  
Airway Epithelial Cells ◽  
Intercellular Adhesion Molecule ◽  
Airway Epithelial ◽  
Intercellular Adhesion Molecule 1 ◽  
Lymphocyte Adhesion ◽  
Dust Extract

The dust of hog confinement facilities induces airway inflammation. Mechanisms by which this dust modulates inflammation are not completely defined, although it is clear that exposure to dust can modulate both epithelial cell and inflammatory cell function. In this work, we demonstrate that airway epithelial cell (BEAS-2B) treatment with hog barn dust extract (HDE) results in augmentation of peripheral blood lymphocyte adhesion to epithelial cell cultures in vitro. The augmentation of lymphocyte adhesion to epithelial cells is dependent on the concentration of HDE and time of HDE exposure, with twofold increases observed by 3 h and maintained at 24 h. Similar results are seen with primary human bronchial epithelial cells in culture. Lymphocyte adhesion to epithelial cells is inhibited in a concentration-dependent fashion by the treatment of epithelial cells with antibody to intercellular adhesion molecule-1 (ICAM-1). In addition, HDE exposure of epithelial cells results in an approximate twofold increase in ICAM-1 expression as determined by flow cytometry analysis. Pretreatment of epithelial cells with a protein kinase C-α (PKC-α) inhibitor, Gö-6976, also inhibited subsequent lymphocyte adhesion to HDE-exposed epithelial cells. These data suggest that airway epithelial cell HDE exposure enhances subsequent lymphocyte adhesion to epithelial cells that is mediated in part by HDE modulation of ICAM-1 expression and PKC-α.

Dynamic interaction between airway epithelial cells andStaphylococcus aureus

2004 ◽  
Vol 287 (3) ◽  
pp. L543-L551 ◽  
Author(s):  
Mauricio C. A. da Silva ◽  
Jean-Marie Zahm ◽  
Delphine Gras ◽  
Odile Bajolet ◽  
Michel Abely ◽  
...  
Keyword(s):  
Epithelial Cells ◽  
Pulmonary Infection ◽  
Airway Epithelial Cell ◽  
Cell Damage ◽  
Airway Epithelial Cells ◽  
Host Cells ◽  
Airway Epithelial ◽  
Bacterial Concentration ◽  
Airway Infections ◽  
Airway Cells

Staphylococcus aureus is a major cause of pulmonary infection, particularly in cystic fibrosis (CF) patients. However, few aspects of the interplay between S. aureus and host airway epithelial cells have been investigated thus far. We investigated by videomicroscopy the time- and bacterial concentration-dependent (104, 106, and 108CFU/ml) effect of S. aureus on adherence, internalization, and the associated damage of the airway epithelial cells. The balance between the secretion by S. aureus of the α-toxin virulence factor and by the airway cells of the antibacterial secretory leukoproteinase inhibitor (SLPI) was also analyzed. After 1 h of interaction, whatever the initial bacterial concentration, a low percentage of S. aureus (<8%) adhered to airway cells, and no airway epithelial cell damage was observed. In contrast, after 24 h of incubation, more bacteria adhered to airway epithelial cells, internalized bacteria were observed, and a bacterial concentration-dependent effect on airway cell damage was observed. At 24 h, most airway cells incubated with bacteria at 108CFU/ml exhibited a necrotic phenotype. The necrosis was preceded by a transient apoptotic process. In parallel, we observed a time- and bacterial concentration-dependent decrease in SLPI and increase in α-toxin expression. These results suggest that airway cells can defend against S. aureus in the early stages of infection. However, in later phases, there is a marked imbalance between the bactericidal capacity of host cells and bacterial virulence. These findings reinforce the potential importance of S. aureus in the pathogenicity of airway infections, including those observed early in CF patients.

scholarly journals Effect of inhaled indomethacin on distilled water-induced airway epithelial cell swelling

2002 ◽  
Vol 92 (1) ◽  
pp. 155-161 ◽  
Author(s):  
Hiroyuki Mochizuki ◽  
Yasushi Ohki ◽  
Hirokazu Arakawa ◽  
Masahiko Kato ◽  
Kenichi Tokuyama ◽  
...  
Keyword(s):  
Epithelial Cells ◽  
Guinea Pigs ◽  
Airway Epithelial Cell ◽  
Airway Epithelial Cells ◽  
Cell Swelling ◽  
Distilled Water ◽  
Airway Epithelial ◽  
Airway Mucosa ◽  
Lung Resistance ◽  
Morphometric Assessment

We evaluated the mechanism of the anti-asthmatic effect of inhaled indomethacin (Indo) by using an animal model (guinea pigs) of airway inflammation. After being exposed to either ozone or room air at identical flow rates (5 l/min) for 2 h, guinea pigs were anesthetized, tracheostomized, and lung resistance (Rl) was subsequently measured. Guinea pigs inhaled either saline or Indo (1.5 mg/ml) for 1 min before undergoing an ultrasonically nebulized distilled water (UNDW) inhalation test. Rl increased significantly after 10 min of UNDW inhalation in the room air and ozone groups but more so in the ozone group. This increase in Rl was significantly suppressed by pretreatment with Indo. In the morphometric assessment of airway mucosa, a significant swelling of the epithelial cells after UNDW inhalation was observed in both the room air and ozone groups but especially so in the ozone group. This increase was also suppressed with Indo pretreatment. These results suggest that the increase in Rl and the swelling of airway epithelial cells induced by inhaled UNDW in ozone-exposed guinea pigs was suppressed by pretreatment of inhaled Indo and that this suppression may be one of the reasons for the anti-asthmatic effect of inhaled Indo.

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