title: β2-Agonists upregulate PDE4 mRNA but not protein or activity in human airway smooth muscle cells from asthmatic and nonasthmatic volunteers.
abstract: β(2)-Adrenergic receptor (β2AR) agonists induce airway relaxation via cAMP. Phosphodiesterase (PDE)s degrade and regulate cAMP, and in airway smooth muscle (ASM) cells PDE4D degrades cAMP. Long-acting β(2)-agonists are now contraindicated as monotherapy for asthma, and increased PDE4D has been speculated to contribute to this phenomenon. In this study we investigated the expression of PDE4D in asthmatic and nonasthmatic ASM cells and its regulation by formoterol and budesonide. Primary ASM cells from people with or without asthma were stimulated with transforming growth factor (TGF)-β(1), formoterol, and/or budesonide. PDE4D mRNA was assessed by real-time PCR, or PCR to assess splice variant production. PDE4D protein was assessed by Western blotting, and we investigated the effect of formoterol on cAMP production and PDE activity. Interleukin (IL)-6 was assessed using ELISA. PDE4D mRNA was dose dependently upregulated by formoterol, with a single splice variant, PDE4D5, present. Formoterol did not induce PDE4D protein at time points between 3 to 72 h, whereas it did induce and increase IL-6 secretion. We pretreated cells with actinomycin D and a proteasome inhibitor, MG132, and found no evidence of alterations in mRNA, protein expression, or degradation of PDE4D. Finally PDE activity was not altered by formoterol. This study shows, for the first time, that PDE4D5 is predominantly expressed in human ASM cells from people with and without asthma and that formoterol does not upregulate PDE4D protein production. This leads us to speculate that continual therapy with β2AR agonists is unlikely to cause PDE4-mediated tachyphylaxis.
authors.affiliation: Cell Biology Group, Woolcock Institute of Medical Research, School of Medical Sciences, The Univ. of Sydney, Sydney, NSW, Australia. niimi_k1002@yahoo.co.jp
authors.forename: Kyoko
authors.initials: K
authors.lastname: Niimi
authors.forename: Qi
authors.initials: Q
authors.lastname: Ge
authors.forename: Lyn M
authors.initials: LM
authors.lastname: Moir
authors.forename: Alaina J
authors.initials: AJ
authors.lastname: Ammit
authors.forename: Thomas
authors.initials: T
authors.lastname: Trian
authors.forename: Janette K
authors.initials: JK
authors.lastname: Burgess
authors.forename: Judith L
authors.initials: JL
authors.lastname: Black
authors.forename: Brian G G
authors.initials: BG
authors.lastname: Oliver
mesh_terms: D058666:Adrenergic beta-2 Receptor Agonists / Q000494:pharmacology*; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001249:Asthma / Q000473:pathology*; D019819:Budesonide / Q000494:pharmacology; D016022:Case-Control Studies; D015815:Cell Adhesion Molecules / Q000378:metabolism; D002478:Cells, Cultured; D054703:Cyclic Nucleotide Phosphodiesterases, Type 4 / Q000235:genetics / Q000378:metabolism*; D004983:Ethanolamines / Q000494:pharmacology*; D005260:Female; D000068759:Formoterol Fumarate; D005938:Glucocorticoids / Q000494:pharmacology; D006801:Humans; D015850:Interleukin-6 / Q000378:metabolism; D007527:Isoenzymes / Q000235:genetics / Q000378:metabolism; D008297:Male; D008840:Microfilament Proteins / Q000378:metabolism; D008875:Middle Aged; D032389:Myocytes, Smooth Muscle / Q000187:drug effects* / Q000201:enzymology / Q000378:metabolism; D010750:Phosphoproteins / Q000378:metabolism; D010766:Phosphorylation; D012333:RNA, Messenger / Q000378:metabolism*; D018343:Receptors, Adrenergic, beta-2 / Q000378:metabolism; D013618:Tachyphylaxis; D014158:Transcription, Genetic / Q000187:drug effects*; D055815:Young Adult; D000098662:Vasodilator-Stimulated Phosphoprotein
chemical_list: D058666:Adrenergic beta-2 Receptor Agonists; D015815:Cell Adhesion Molecules; D004983:Ethanolamines; D005938:Glucocorticoids; C508600:IL6 protein, human; D015850:Interleukin-6; D007527:Isoenzymes; D008840:Microfilament Proteins; D010750:Phosphoproteins; D012333:RNA, Messenger; D018343:Receptors, Adrenergic, beta-2; D000098662:Vasodilator-Stimulated Phosphoprotein; D019819:Budesonide; D054703:Cyclic Nucleotide Phosphodiesterases, Type 4; D000068759:Formoterol Fumarate