Intracellular interactions of umeclidinium and vilanterol in human airway smooth muscle

Intracellular interactions of umeclidinium and vilanterol in human airway smooth muscle

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Nooreen Shaikh,1,2 Malcolm Johnson,3 David A Hall,4 Kian Fan Chung,1,2 John H Riley,3 Sally Worsley,5 Pankaj K Bhavsar1,2 1Experimental Studies, National Heart and Lung Institute, Imperial College London, 2Biomedical Research Unit, Royal Brompton and Harefield NHS Trust, London, 3Respiratory Global Franchise, GlaxoSmithKline, Uxbridge, 4Fibrosis and Lung Injury Development Planning Unit, GlaxoSmithKline, Stevenage, 5Respiratory Research & Development, GlaxoSmithKline, Uxbridge, UK Background: Intracellular mechanisms of action of umeclidinium (UMEC), a long-acting muscarinic receptor antagonist, and vilanterol HBS (VI), a long-acting β2-adrenoceptor (β2R) agonist, were investigated in target cells: human airway smooth-muscle cells (ASMCs).Materials and methods: ASMCs from tracheas of healthy lung-transplant donors were treated with VI, UMEC, UMEC and VI combined, or control compounds (salmeterol, propranolol, ICI 118.551, or methacholine [MCh]).Cyclic adenosine monophosphate (cAMP) was measured using an enzyme-linked immunosorbent assay, intracellular free calcium ([Ca2+]i) using a fluorescence assay, and regulator of G-protein signaling 2 (RGS2) messenger RNA using real-time quantitative polymerase chain reaction.Results: VI and salmeterol (10–12–10–6 M) induced cAMP production from ASMCs in a concentration-dependent manner, which was greater for VI at all concentrations.

β2R antagonism by propranolol or ICI 118.551 (10–12–10–4 M) resulted in concentration-dependent inhibition of VI-induced cAMP production, and ICI 118.551 was more potent.MCh (5×10–6 M, 30 minutes) attenuated VI-induced cAMP production (P<0.05), whereas pretreatment with UMEC (10–8 M, 1 hour) restored the magnitude of VI-induced cAMP production.

ASMC stimulation with MCh (10–11–5×10–6 M) resulted in a concentration-dependent increase in [Ca2+]i, which Table Runner was attenuated with UMEC pretreatment.Reduction of MCh-induced [Ca2+]i release was greater with UMEC + VI versus UMEC.UMEC enhanced VI-induced RGS2 messenger RNA expression.Conclusion: These data indicate that UMEC reverses cholinergic inhibition of VI-induced cAMP production, and is a more potent muscarinic receptor antagonist when in combination with VI versus either alone.Keywords: COPD pharmacology, cough/mechanisms/pharmacology, drug reactions.