Glucocorticosteroids and β₂-adrenoceptor agonists synergize to inhibit airway smooth muscle remodeling.
Airway remodeling, including increased airway smooth muscle (ASM) mass and contractility, contributes to increased airway narrowing in asthma. Increased ASM mass may be caused by exposure to mitogens, including platelet-derived growth factor (PDGF) and collagen type I, which induce a proliferative, hypocontractile ASM phenotype. In contrast, prolonged exposure to insulin induces a hypercontractile phenotype. Glucocorticosteroids and β₂-adrenoceptor agonists synergize to increase glucocorticosteroid receptor translocation in ASM cells; however, the impact of this synergism on phenotype modulation is unknown. Using bovine tracheal smooth muscle, we investigated the effects of the glucocorticosteroids fluticasone (10 nM), budesonide (30 nM), and dexamethasone (0.1-1 μM) and the combination of low concentrations of fluticasone (3-100 pM) and fenoterol (10 nM) on ASM phenotype switching in response to PDGF (10 ng/ml), collagen type I (50 μg/ml), and insulin (1 μM). All glucocorticosteroids inhibited PDGF- and collagen I-induced proliferation and hypocontractility, with the effects of collagen I being less susceptible to glucocorticosteroid action. At 100-fold lower concentrations, fluticasone (100 pM) synergized with fenoterol to prevent PDGF- and collagen I-induced phenotype switching. This inhibition of ASM phenotype switching was associated with a normalization of the PDGF-induced decrease in the cell cycle inhibitors p21(WAF1/CIP1) and p57(KIP2). At this concentration, fluticasone also prevented the insulin-induced hypercontractile phenotype. At even lower concentrations, fluticasone (3 pM) synergized with fenoterol to inhibit this phenotype switch. Collectively, these findings indicate that glucocorticosteroids and β₂-agonists synergistically inhibit ASM phenotype switching, which may contribute to the increased effectiveness of combined treatment with glucocorticosteroids and β₂-agonists in asthma.
Department of Molecular Pharmacology, University Centre for Pharmacy, University of Groningen, Antonius Deusinglaan 1, 9713 AV Groningen, The Netherlands. b.g.j.dekkers@rug.nl
Bart G J
BG
Dekkers
Adnan
A
Pehlic
Raissa
R
Mariani
I Sophie T
IS
Bos
Herman
H
Meurs
Johan
J
Zaagsma
D058666:Adrenergic beta-2 Receptor Agonists / Q000494:pharmacology*; D056151:Airway Remodeling / Q000187:drug effects* / Q000502:physiology; D000730:Androstadienes / Q000494:pharmacology; D000818:Animals; D019819:Budesonide / Q000494:pharmacology; D002417:Cattle; D002453:Cell Cycle / Q000187:drug effects; D049109:Cell Proliferation / Q000187:drug effects; D024042:Collagen Type I / Q000378:metabolism; D050759:Cyclin-Dependent Kinase Inhibitor p21 / Q000378:metabolism; D050761:Cyclin-Dependent Kinase Inhibitor p57 / Q000378:metabolism; D003907:Dexamethasone / Q000494:pharmacology; D004357:Drug Synergism; D005280:Fenoterol / Q000494:pharmacology; D000068298:Fluticasone; D005938:Glucocorticoids / Q000494:pharmacology*; D007328:Insulin / Q000378:metabolism; D008934:Mitogens / Q000494:pharmacology; D009119:Muscle Contraction / Q000187:drug effects; D009130:Muscle, Smooth / Q000187:drug effects* / Q000378:metabolism / Q000502:physiology; D032389:Myocytes, Smooth Muscle / Q000187:drug effects / Q000378:metabolism / Q000502:physiology; D010641:Phenotype; D010982:Platelet-Derived Growth Factor / Q000378:metabolism; D012137:Respiratory System / Q000187:drug effects / Q000378:metabolism; D014132:Trachea / Q000187:drug effects / Q000378:metabolism / Q000502:physiology
D058666:Adrenergic beta-2 Receptor Agonists; D000730:Androstadienes; D024042:Collagen Type I; D050759:Cyclin-Dependent Kinase Inhibitor p21; D050761:Cyclin-Dependent Kinase Inhibitor p57; D005938:Glucocorticoids; D007328:Insulin; D008934:Mitogens; D010982:Platelet-Derived Growth Factor; D005280:Fenoterol; D019819:Budesonide; D003907:Dexamethasone; D000068298:Fluticasone