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.

Mechanical strain increases velocity and extent of shortening in cultured airway smooth muscle cells

1999 ◽  
Vol 277 (2) ◽  
pp. L343-L348 ◽  
Author(s):  
Paul G. Smith ◽  
Chaity Roy ◽  
Jamie Dreger ◽  
Frank Brozovich
Keyword(s):  
Smooth Muscle ◽  
Mechanical Stress ◽  
Airway Smooth Muscle ◽  
Light Chain ◽  
Myosin Light Chain ◽  
Mechanical Strain ◽  
Airway Smooth Muscle Cells ◽  
Maximal Velocity ◽  
Cell Contractility ◽  
Cell Shortening

Abnormal mechanical stress on lung tissue is associated with increased mass and contractility of airway smooth muscle (ASM). We have reported that cultured ASM cells subjected to cyclic strain exhibit increased myosin light chain kinase (MLCK) and stress filaments. Increased MLCK may increase contractile velocity, whereas increased stress filaments could impede cell shortening by increasing the cell’s internal load. To study strain-induced changes in cell contractility, the time course of shortening of individual cells exposed to 90 mM KCl was recorded. Length vs. time plots revealed significantly greater maximal velocity of shortening in strain cells than control (no strain). This correlated with an increase in MLCK and myosin light chain phosphorylation measured in strain cells in separate experiments. The extent of cell shortening tended to be greater in the strain cells so that increased impedance to shortening was not detected. Mechanical stress may therefore increase the contractility of ASM by increasing the content of MLCK.

Airway smooth muscle tone modulates mechanically induced cytoskeletal stiffening and remodeling

2005 ◽  
Vol 99 (2) ◽  
pp. 634-641 ◽  
Author(s):  
Linhong Deng ◽  
Nigel J. Fairbank ◽  
Darren J. Cole ◽  
Jeffrey J. Fredberg ◽  
Geoffrey N. Maksym
Keyword(s):  
Smooth Muscle ◽  
Mechanical Stress ◽  
Applied Stress ◽  
Airway Smooth Muscle ◽  
Cell Activation ◽  
Structural Changes ◽  
Muscle Tone ◽  
Residual Effects ◽  
Cell Stiffness ◽  
Functional Changes

The application of mechanical stresses to the airway smooth muscle (ASM) cell causes time-dependent cytoskeletal stiffening and remodeling (Deng L, Fairbank NJ, Fabry B, Smith PG, and Maksym GN. Am J Physiol Cell Physiol 287: C440–C448, 2004). We investigated here the extent to which these behaviors are modulated by the state of cell activation (tone). Localized mechanical stress was applied to the ASM cell in culture via oscillating beads (4.5 μm) that were tightly bound to the actin cytoskeleton (CSK). Tone was reduced from baseline level using a panel of relaxant agonists (10−3 M dibutyryl cAMP, 10−4 M forskolin, or 10−6 M formoterol). To assess functional changes, we measured cell stiffness (G′) using optical magnetic twisting cytometry, and to assess structural changes of the CSK we measured actin accumulation in the neighborhood of the bead. Applied mechanical stress caused a twofold increase in G′ at 120 min. After cessation of applied stress, G′ diminished only 24 ± 6% (mean ± SE) at 1 h, leaving substantial residual effects that were largely irreversible. However, applied stress-induced stiffening could be prevented by ablation of tone. Ablation of tone also inhibited the amount of actin accumulation induced by applied mechanical stress ( P < 0.05). Thus the greater the contractile tone, the greater was applied stress-induced CSK stiffening and remodeling. As regards pathobiology of asthma, this suggests a maladaptive positive feedback in which tone potentiates ASM remodeling and stiffening that further increases stress and possibly leads to worsening airway function.

Mechanical strain memory in airway smooth muscle

2000 ◽  
Vol 278 (5) ◽  
pp. C895-C904 ◽  
Author(s):  
Wah-Lun Chan ◽  
Jeanette Silberstein ◽  
Chi-Ming Hai
Keyword(s):  
Smooth Muscle ◽  
Airway Smooth Muscle ◽  
Mechanical Strain ◽  
Control Level ◽  
High Stress ◽  
Peak Stress ◽  
Airway Smooth Muscle Cells ◽  
Initial Length ◽  
Myosin Phosphorylation ◽  
Contraction And Relaxation

We investigated the effect of a single rapid stretch on poststretch force and myosin phosphorylation in bovine tracheal smooth muscle. When unstimulated muscle strips were stretched from suboptimal length to optimal length ( L o), poststretch steady-state force was not significantly different from that of unstretched control at L o. However, when carbachol-activated muscle strips were stretched from suboptimal length to L o, poststretch force and myosin phosphorylation were lower than control and significantly correlated with initial length. When poststretch muscle strips were allowed to relax for 1 h and then activated by K+ depolarization, the developed force remained significantly correlated with initial length. When the same strain was applied in 23 increments to minimize peak stress, poststretch force and myosin phosphorylation increased significantly, approaching the levels expected at L o. Furthermore, poststretch force development increased after each cycle of contraction and relaxation, approaching the control level after four cycles. These results suggest that activated airway smooth muscle cells can retain relatively precise memory of past strain when they are stretched rapidly with high stress.

Coupling mechanisms in airway smooth muscle

1990 ◽  
Vol 258 (4) ◽  
pp. L119-L133 ◽  
Author(s):  
R. F. Coburn ◽  
C. B. Baron
Keyword(s):  
Smooth Muscle ◽  
Membrane Potential ◽  
Airway Smooth Muscle ◽  
Electromechanical Coupling ◽  
Cell Function ◽  
Surface Membrane ◽  
Smooth Muscles ◽  
Membrane Receptors ◽  
Airway Smooth Muscle Cells ◽  
Coupling Mechanisms

This review documents available information about coupling mechanisms involved in airway smooth muscle force development and maintenance and relaxation of force. Basic concepts, obtained from experiments performed on many different mammalian cell types, are in place regarding coupling between surface membrane receptors and cell function; these concepts are considered as a framework for understanding coupling between receptors and contractile proteins in smooth muscles and in airway smooth muscles. We have divided various components of coupling mechanisms into those dependent on changes in the surface membrane potential (electromechanical coupling) and those independent of the surface membrane potential (pharmacomechanical coupling). We have, to some degree, emphasized modulation of coupling mechanisms by intrasurface membrane microprocessing or by second messengers. A challenge for the future is to obtain a better understanding of how coupling mechanisms are altered or modulated during different phases of contractions evoked by a single agonist and under conditions of multiple agonist exposure to airway smooth muscle cells.

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.

Cyclic mechanical strain‐induced proliferation and migration of human airway smooth muscle cells: role of EMMPRIN and MMPs

2005 ◽  
Vol 19 (11) ◽  
pp. 1507-1509 ◽  
Author(s):  
Nadia A. Hasaneen ◽  
Stanley Zucker ◽  
Jian Cao ◽  
Christian Chiarelli ◽  
Reynold A. Panettieri ◽  
...  
Keyword(s):  
Smooth Muscle ◽  
Smooth Muscle Cells ◽  
Airway Smooth Muscle ◽  
Mechanical Strain ◽  
Muscle Cells ◽  
Airway Smooth Muscle Cells ◽  
Human Airway Smooth Muscle ◽  
And Migration ◽  
Proliferation And Migration

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.

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