Long-acting β2-agonists increase fluticasone propionate-induced mitogen-activated protein kinase phosphatase 1 (MKP-1) in airway smooth muscle cells

PLoS One. 2013;8(3):e59635. doi: 10.1371/journal.pone.0059635. Epub 2013 Mar 22.

Abstract

Mitogen-activated protein kinase phosphatase 1 (MKP-1) represses MAPK-driven signalling and plays an important anti-inflammatory role in asthma and airway remodelling. Although MKP-1 is corticosteroid-responsive and increased by cAMP-mediated signalling, the upregulation of this critical anti-inflammatory protein by long-acting β2-agonists and clinically-used corticosteroids has been incompletely examined to date. To address this, we investigated MKP-1 gene expression and protein upregulation induced by two long-acting β2-agonists (salmeterol and formoterol), alone or in combination with the corticosteroid fluticasone propionate (abbreviated as fluticasone) in primary human airway smooth muscle (ASM) cells in vitro. β2-agonists increased MKP-1 protein in a rapid but transient manner, while fluticasone induced sustained upregulation. Together, long-acting β2-agonists increased fluticasone-induced MKP-1 and modulated ASM synthetic function (measured by interleukin 6 (IL-6) and interleukin 8 (IL-8) secretion). As IL-6 expression (like MKP-1) is cAMP/adenylate cyclase-mediated, the long-acting β2-agonist formoterol increased IL-6 mRNA expression and secretion. Nevertheless, when added in combination with fluticasone, β2-agonists significantly repressed IL-6 secretion induced by tumour necrosis factor α (TNFα). Conversely, as IL-8 is not cAMP-responsive, β2-agonists significantly inhibited TNFα-induced IL-8 in combination with fluticasone, where fluticasone alone was without repressive effect. In summary, long-acting β2-agonists increase fluticasone-induced MKP-1 in ASM cells and repress synthetic function of this immunomodulatory airway cell type.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adrenergic beta-2 Receptor Agonists / pharmacology*
  • Androstadienes / pharmacology*
  • Blotting, Western
  • Cells, Cultured
  • Dual Specificity Phosphatase 1 / metabolism*
  • Enzyme-Linked Immunosorbent Assay
  • Fluticasone
  • Humans
  • Myocytes, Smooth Muscle / drug effects*
  • Myocytes, Smooth Muscle / enzymology*
  • Real-Time Polymerase Chain Reaction

Substances

  • Adrenergic beta-2 Receptor Agonists
  • Androstadienes
  • Fluticasone
  • Dual Specificity Phosphatase 1

Grants and funding

This research was funded by a project grant (570856) from the National Health and Medical Research Council of Australia (www.nhmrc.gov.au). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.