Stiffness changes in cultured airway smooth muscle cells

2002 ◽  
Vol 283 (3) ◽  
pp. C792-C801 ◽  
Author(s):  
Steven S. An ◽  
Rachel E. Laudadio ◽  
Jean Lai ◽  
Rick A. Rogers ◽  
Jeffrey J. Fredberg
Keyword(s):  
Smooth Muscle ◽  
Airway Smooth Muscle ◽  
Actin Polymerization ◽  
Kinase Inhibitor ◽  
Cell Stiffness ◽  
Airway Smooth Muscle Cells ◽  
Atpase Inhibitor ◽  
Calmodulin Antagonist ◽  
Relative Contribution ◽  
Dose Dependent Fashion

Airway smooth muscle (ASM) cells in culture stiffen when exposed to contractile agonists. Such cell stiffening may reflect activation of the contractile apparatus as well as polymerization of cytoskeletal biopolymers. Here we have assessed the relative contribution of these mechanisms in cultured ASM cells stimulated with serotonin (5-hydroxytryptamine; 5-HT) in the presence or absence of drugs that inhibit either myosin-based contraction or polymerization of filamentous (F) actin. Magnetic twisting cytometry was used to measure cell stiffness, and associated changes in structural organization of actin cytoskeleton were evaluated by confocal microscopy. We found that 5-HT increased cell stiffness in a dose-dependent fashion and also elicited rapid formation of F-actin as marked by increased intensity of FITC-phalloidin staining in these cells. A calmodulin antagonist (W-7), a myosin light chain kinase inhibitor (ML-7) and a myosin ATPase inhibitor (BDM) each ablated the stiffening response but not the F-actin polymerization induced by 5-HT. Agents that inhibited the formation of F-actin (cytochalasin D, latrunculin A, C3 exoenzyme, and Y-27632) attenuated both baseline stiffness and the extent of cell stiffening in response to 5-HT. Together, these data suggest that agonist-evoked stiffening of cultured ASM cells requires actin polymerization as well as myosin activation and that neither actin polymerization nor myosin activation by itself is sufficient to account for the cell stiffening response.

Urokinase potentiates PDGF-induced chemotaxis of human airway smooth muscle cells

2003 ◽  
Vol 284 (6) ◽  
pp. L1020-L1026 ◽  
Author(s):  
Stephen M. Carlin ◽  
Michael Roth ◽  
Judith L. Black
Keyword(s):  
Smooth Muscle ◽  
Smooth Muscle Cells ◽  
Airway Smooth Muscle ◽  
Kinase Inhibitor ◽  
Airway Remodeling ◽  
Muscle Cells ◽  
Mek Inhibitor ◽  
Airway Smooth Muscle Cells ◽  
Human Airway Smooth Muscle ◽  
Human Airway

We investigated the chemotactic action of PDGF and urokinase on human airway smooth muscle (HASM) cells in culture. Cells were put in collagen-coated transwells with 8-μm perforations, incubated for 4 h with test compounds, then fixed, stained, and counted as migrated nuclei by microscopy. Cells from all culture conditions showed some basal migration (migration in the absence of stimuli during the assay), but cells preincubated for 24 h in 10% FBS or 20 ng/ml PDGF showed higher basal migration than cells quiesced in 1% FBS. PDGFBB, PDGFAA, and PDGFABwere all chemotactic when added during the assay. PDGF chemotaxis was blocked by the phosphatidyl 3′-kinase inhibitor LY-294002, the MEK inhibitor U-0126, PGE2, formoterol, pertussis toxin, and the Rho kinase inhibitor Y-27632. Urokinase alone had no stimulatory effect on migration of quiescent cells but caused a dose-dependent potentiation of chemotaxis toward PDGF. Urokinase also potentiated the elevated basal migration of cells pretreated in 10% FBS or PDGF. This potentiating effect of urokinase appears to be novel. We conclude that PDGF and similar cytokines may be important factors in airway remodeling by redistribution of smooth muscle cells during inflammation and that urokinase may be important in potentiating the response.

Actin reorganization in airway smooth muscle cells involves Gq and Gi-2 activation of Rho

1999 ◽  
Vol 277 (3) ◽  
pp. L653-L661 ◽  
Author(s):  
Carol A. Hirshman ◽  
Charles W. Emala
Keyword(s):  
Smooth Muscle ◽  
Smooth Muscle Cells ◽  
Airway Smooth Muscle ◽  
Actin Polymerization ◽  
Muscle Cells ◽  
Fiber Formation ◽  
Airway Smooth Muscle Cells ◽  
Actin Reorganization ◽  
Endothelin 1 ◽  
In Cells

Extracellular stimuli induce cytoskeleton reorganization (stress-fiber formation) in cells and Ca2+ sensitization in intact smooth muscle preparations by activating signaling pathways that involve Rho proteins, a subfamily of the Ras superfamily of monomeric G proteins. In airway smooth muscle, the agonists responsible for cytoskeletal reorganization via actin polymerization are poorly understood. Carbachol-, lysophosphatidic acid (LPA)-, and endothelin-1-induced increases in filamentous actin staining are indicative of actin reorganization (filamentous-to-globular actin ratios of 2.4 ± 0.3 in control cells, 6.7 ± 0.8 with carbachol, 7.2 ± 0.8 with LPA, and 7.4 ± 0.9 with endothelin-1; P < 0.001; n = 14 experiments). Although the effect of all agonists was blocked by C3 exoenzyme (inactivator of Rho), only carbachol was blocked by pertussis toxin. Although carbachol-induced actin reorganization was blocked in cells pretreated with antisense oligonucleotides directed against Gαi-2 alone, LPA- and endothelin-1-induced actin reorganization were only blocked when both Gαi-2 and Gqα were depleted. These data indicate that in human airway smooth muscle cells, carbachol induces actin reorganization via a Gαi-2pathway, whereas LPA or endothelin-1 induce actin reorganization via either a Gαi-2 or a Gqα pathway.

Prostanoids mediate IL-1β-induced β-adrenergic hyporesponsiveness in human airway smooth muscle cells

1998 ◽  
Vol 275 (3) ◽  
pp. L491-L501 ◽  
Author(s):  
Johanne D. Laporte ◽  
Paul E. Moore ◽  
Reynold A. Panettieri ◽  
Winfried Moeller ◽  
Joachim Heyder ◽  
...  
Keyword(s):  
Smooth Muscle ◽  
Airway Smooth Muscle ◽  
Cell Stiffness ◽  
Airway Smooth Muscle Cells ◽  
Human Airway Smooth Muscle ◽  
Human Airway ◽  
Heterologous Desensitization ◽  
Cox 2 ◽  
Inhibitor Of Protein Synthesis ◽  
Induced Changes

We have previously reported that pretreatment of cultured human airway smooth muscle (HASM) cells with interleukin-1β (IL-1β) results in decreased β-adrenergic responsiveness. The purpose of this study was to determine whether prostanoids released as a result of cyclooxygenase-2 (COX-2) induction by IL-1β contribute to this effect of the cytokine. Confluent serum-deprived HASM cells were studied in passages 4–7. IL-1β (20 ng/ml for 22 h) reduced the ability of the β-agonist isoproterenol (Iso) to decrease stiffness of HASM cells as measured by magnetic twisting cytometry. The effect of IL-1β on Iso-induced changes in cell stiffness was abolished by nonselective [indomethacin (Indo), 10−6 M] and selective (NS-398, 10−5 M) COX-2 inhibitors. Indo and NS-398 also inhibited both the increased basal cAMP and the decreases in Iso-stimulated cAMP production induced by IL-1β. IL-1β (20 ng/ml for 22 h) caused an increase in both basal (15-fold) and arachidonic acid (AA)-stimulated (10-fold) PGE2 release. Indo blocked basal and AA-stimulated PGE2 release in both control and IL-1β-treated cells. NS-398 also markedly reduced basal and AA-stimulated PGE2release in IL-1β-treated cells but had no significant effect on AA-stimulated PGE2 release in control cells. Western blot analysis confirmed the induction of COX-2 by IL-1β. Exogenously administered PGE2(10−7 M, 22 h) caused a significant reduction in the ability of Iso to decrease cell stiffness, mimicking the effects of IL-1β. Cycloheximide (10 μg/ml for 24 h), an inhibitor of protein synthesis, also abolished the effects of IL-1β on Iso-induced cell stiffness changes and cAMP formation. In summary, our results indicate that IL-1β significantly increases prostanoid release by HASM cells as a result of increased COX-2 expression. The prostanoids appear to contribute to β-adrenergic hyporesponsiveness, perhaps by heterologous desensitization of the β2 receptor.

Selected Contribution: Time course and heterogeneity of contractile responses in cultured human airway smooth muscle cells

2001 ◽  
Vol 91 (2) ◽  
pp. 986-994 ◽  
Author(s):  
Ben Fabry ◽  
Geoffrey N. Maksym ◽  
Stephanie A. Shore ◽  
Paul E. Moore ◽  
Reynold A. Panettieri ◽  
...  
Keyword(s):  
Smooth Muscle ◽  
Airway Smooth Muscle ◽  
Time Course ◽  
Detection System ◽  
Loss Modulus ◽  
Cell Stiffness ◽  
Airway Smooth Muscle Cells ◽  
Human Airway Smooth Muscle ◽  
Cells In Culture ◽  
Human Airway

We measured the time course and heterogeneity of responses to contractile and relaxing agonists in individual human airway smooth muscle (HASM) cells in culture. To this end, we developed a microrheometer based on magnetic twisting cytometry adapted with a novel optical detection system. Ferromagnetic beads (4.5 μm) coated with Arg-Gly-Asp peptide were bound to integrins on the cell surface. The beads were twisted in a sinusoidally varying magnetic field at 0.75 Hz. Oscillatory bead displacements were recorded using a phase-synchronized video camera. The storage modulus (cell stiffness; G′), loss modulus (friction; G"), and hysteresivity (η; ratio of G" to G′) could be determined with a time resolution of 1.3 s. Within 5 s after addition of histamine (100 μM), G′ increased by 2.2-fold, G" increased by 3.0-fold, and η increased transiently from 0.27 to 0.34. By 20 s, η decreased to 0.25, whereas G′ and G" remained above baseline. Comparable results were obtained with bradykinin (1 μM). These changes in G′, G", and η measured in cells were similar to but smaller than those reported for intact muscle strips. When we ablated baseline tone by adding the relaxing agonist dibutyryl cAMP (1 mM), G′ decreased within 5 min by 3.3-fold. With relaxing and contracting agonists, G′ could be manipulated through a contractile range of 7.3-fold. Cell populations exhibited a log-normal distribution of baseline stiffness (geometric SD = 2.8) and a heterogeneous response to both contractile and relaxing agonists, partly attributable to variability of baseline tone between cells. The total contractile range of the cells (from maximally relaxed to maximally stimulated), however, was independent of baseline stiffness. We conclude that HASM cells in culture exhibit a clear, although heterogeneous, response to contractile and relaxing agonists and express the essential mechanical features characteristic of the contractile response observed at the tissue level.

Selected Contribution: Tryptase-induced PAR-2-mediated Ca2+signaling in human airway smooth muscle cells

2001 ◽  
Vol 91 (2) ◽  
pp. 995-1003 ◽  
Author(s):  
Patrick Berger ◽  
J. Manuel Tunon-De-Lara ◽  
Jean-Pierre Savineau ◽  
Roger Marthan
Keyword(s):  
Smooth Muscle ◽  
Airway Inflammation ◽  
Airway Smooth Muscle ◽  
Airway Smooth Muscle Cells ◽  
Atpase Inhibitor ◽  
Human Airway Smooth Muscle ◽  
Human Airway ◽  
Transient Rise ◽  
Intracellular Ca ◽  
Protein Kinase C Inhibitor

Tryptase, the major mast cell product, is considered to play an important role in airway inflammation and hyperresponsiveness. Tryptase produces different, sometimes opposite, effects on airway responsiveness (bronchoprotection and/or airway contraction). This study was designed to examine the effect of human lung tryptase and activation of protease-activated receptor (PAR)-2 by synthetic activated peptide (AP) SLIGKV-NH2 on Ca2+ signaling in human airway smooth muscle (HASM) cells. Immunocytochemistry revealed that PAR-2 was expressed by HASM cells. Tryptase (7.5–30 mU/ml) induced a concentration-dependent transient relative rise in cytoplasmic Ca2+ concentration ([Ca2+]i) that reached 207 ± 32 nM ( n = 10) measured by indo 1 spectrofluorometry. The protease inhibitors leupeptin or benzamidine (100 μM) abolished tryptase-induced [Ca2+]iincrease. Activation of PAR-2 by AP (1–100 μM) also induced a concentration-dependent transient rise in [Ca2+]i, whereas the reverse peptide produced no effect. There was a homologous desensitization of the [Ca2+]i response on repeated stimulation with tryptase or AP. U-73122, a specific phospholipase C (PLC) antagonist, xestospongin, an inositol trisphosphate (IP3)-receptor antagonist, or thapsigargin, a sarcoplamic Ca2+-ATPase inhibitor, abolished tryptase-induced [Ca2+]iresponse, whereas Ca2+ removal, in the additional presence of EGTA, had no effect. Calphostin C, a protein kinase C inhibitor, increased PAR-2 [Ca2+]i response. Our results indicate that tryptase activates a [Ca2+]iresponse, which appears as PAR-2 mediated in HASM cells. Signal transduction implicates the intracellular Ca2+ store via PLC activation and thus via the IP3 pathway. This study provides evidence that tryptase, which is increasingly recognized as an important mediator in airway inflammation and hyperresponsiveness, is also a potent direct agonist at the site of airway smooth muscle.

Localized mechanical stress induces time-dependent actin cytoskeletal remodeling and stiffening in cultured airway smooth muscle cells

2004 ◽  
Vol 287 (2) ◽  
pp. C440-C448 ◽  
Author(s):  
Linhong Deng ◽  
Nigel J. Fairbank ◽  
Ben Fabry ◽  
Paul G. Smith ◽  
Geoffrey N. Maksym
Keyword(s):  
Smooth Muscle ◽  
Mechanical Stress ◽  
Airway Smooth Muscle ◽  
Cell Function ◽  
Mechanical Strain ◽  
Cell Stiffness ◽  
Airway Smooth Muscle Cells ◽  
Airway Narrowing ◽  
Time Courses ◽  
Altered Cell

Mechanical stress (MS) causes cytoskeletal (CSK) and phenotypic changes in cells. Such changes in airway smooth muscle (ASM) cells might contribute to the pathophysiology of asthma. We have shown that periodic mechanical strain applied to cultured ASM cells alters the structure and expression of CSK proteins and increases cell stiffness and contractility (Smith PG, Moreno R, and Ikebe M. Am J Physiol Lung Cell Mol Physiol 272: L20–L27, 1997; and Smith PG, Deng L, Fredberg JJ, and Maksym GN. Am J Physiol Lung Cell Mol Physiol 285: L456–L463, 2003). However, the mechanically induced CSK changes, altered cell function, and their time courses are not well understood. Here we applied MS to the CSK by magnetically oscillating ferrimagnetic beads bound to the CSK. We quantified CSK remodeling by measuring actin accumulation at the sites of applied MS using fluorescence microscopy. We also measured CSK stiffness using optical magnetic twisting cytometry. We found that, during MS of up to 120 min, the percentage of beads associated with actin structures increased with time. At 60 min, 68.1 ± 1.6% of the beads were associated with actin structures compared with only 6.7 ± 2.8% before MS and 38.4 ± 5.5% in time-matched controls ( P < 0.05). Similarly, CSK stiffness increased more than twofold in response to the MS compared with time-matched controls. These changes were more pronounced than observed with contractile stimulation by 80 mM KCl or 10−4 M acetylcholine. Together, these findings imply that MS is a potent stimulus to enhance stiffness and contractility of ASM cells through CSK remodeling, which may have important implications in airway narrowing and dilation in asthma.

Pharmacological activation changes stiffness of cultured human airway smooth muscle cells

1996 ◽  
Vol 271 (5) ◽  
pp. C1660-C1668 ◽  
Author(s):  
R. D. Hubmayr ◽  
S. A. Shore ◽  
J. J. Fredberg ◽  
E. Planus ◽  
R. A. Panettieri ◽  
...  
Keyword(s):  
Smooth Muscle ◽  
Smooth Muscle Cells ◽  
Airway Smooth Muscle ◽  
Muscle Cells ◽  
High Density ◽  
Cell Stiffness ◽  
Airway Smooth Muscle Cells ◽  
Human Airway Smooth Muscle ◽  
Cyclic Monophosphate ◽  
Human Airway

Using magnetic twisting cytometry (MTC), we measured the cytoskeletal stiffness of adherent human airway smooth muscle (HASM) cells. We hypothesized that modulation of actin-myosin interactions by application of contractile agonists would induce changes in cytoskeletal stiffness. In cells plated on high-density collagen, bradykinin (10(-6) M) and histamine (10(-4) M) increased stiffness by 85 +/- 15 and 68 +/- 16%, respectively. Increases in cell stiffness were also consistently observed after acetylcholine, substance P, and KCl. The bronchodilator agonists isoproterenol, prostaglandin E2, forskolin, dibutryl adenosine 3', 5'-cyclic monophosphate, and 8-bromoguanosine 3', 5'-cyclic monophosphate each caused a dose-dependent decrease in cell stiffness in unstimulated as well as bradykinin-treated cells. HASM cells plated on high-density collagen were stiffer than cells plated on low-density collagen (126 +/- 16 vs. 43 +/- 3 dyn/cm2) and developed more pronounced increases in stiffness in response to bradykinin as well as more pronounced decreases in stiffness in response to isoproterenol. These results are consistent with the hypothesis that modulation of actin-myosin interactions by application of contractile agonists causes changes in cytoskeletal stiffness of HASM cells. MTC may be a valuable tool for evaluating the mechanisms of pharmacomechanical coupling in airway smooth muscle cells in culture.

TNF-α and IFN-γ inversely modulate expression of the IL-17E receptor in airway smooth muscle cells

2006 ◽  
Vol 290 (6) ◽  
pp. L1238-L1246 ◽  
Author(s):  
Stéphane Lajoie-Kadoch ◽  
Philippe Joubert ◽  
Séverine Létuvé ◽  
Andrew J. Halayko ◽  
James G. Martin ◽  
...  
Keyword(s):  
Smooth Muscle ◽  
Smooth Muscle Cells ◽  
Airway Smooth Muscle ◽  
Kinase Inhibitor ◽  
Muscle Cells ◽  
Mitogen Activated Protein Kinase ◽  
Airway Smooth Muscle Cells ◽  
Iκb Kinase ◽  
Tnf Α ◽  
Ifn Γ

The interleukin-17B receptor (IL-17BR) is expressed in a variety of tissues and is upregulated under inflammatory conditions. This receptor binds both its cognate ligand IL-17B and IL-17E/IL-25, a novel cytokine known to promote Th2 responses. The present study shows that airway smooth muscle cells express IL-17BR in vitro and that its expression is upregulated by TNF-α and downregulated by IFN-γ. Our data indicate that TNF-α upregulates IL-17BR mainly through nuclear factor-κB as assessed with the IκB kinase 2 inhibitor AS-602868. In addition, both IFN-γ and dexamethasone are able to antagonize a TNF-α-induced IL-17BR increase in mRNA expression. The mitogen-activated protein kinase kinase inhibitor U0126 totally reversed the inhibition observed with IFN-γ, suggesting the involvement of the extracellular signal-regulated kinase pathway in this effect. In addition, on stimulation with IL-17E, airway smooth muscle cells increase their expression of ECM components, namely procollagen-αI and lumican mRNA. Furthermore, immunohistochemical analysis of biopsies from asthmatic subjects reveals that this receptor is abundant in smooth muscle layers. This is the first report showing IL-17BR receptor in structural cells of the airways. Our results suggest a potential proremodeling effect of IL-17E on airway smooth muscle cells through the induction of ECM and that its receptor is upregulated by proinflammatory conditions.

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