Epinephrine Activation of the β2-Adrenoceptor Is Required for IL-13-Induced Mucin Production in Human Bronchial Epithelial Cells

PLoS One. 2015 Jul 10;10(7):e0132559. doi: 10.1371/journal.pone.0132559. eCollection 2015.

Abstract

Mucus hypersecretion by airway epithelium is a hallmark of inflammation in allergic asthma and results in airway narrowing and obstruction. Others have shown that administration a TH2 cytokine, IL-13 is sufficient to cause mucus hypersecretion in vivo and in vitro. Asthma therapy often utilizes β2-adrenoceptor (β2AR) agonists, which are effective acutely as bronchodilators, however chronic use may lead to a worsening of asthma symptoms. In this study, we asked whether β2AR signaling in normal human airway epithelial (NHBE) cells affected mucin production in response to IL-13. This cytokine markedly increased mucin production, but only in the presence of epinephrine. Mucin production was blocked by ICI-118,551, a preferential β2AR antagonist, but not by CGP-20712A, a preferential β1AR antagonist. Constitutive β2AR activity was not sufficient for IL-13 induced mucin production and β-agonist-induced signaling is required. A clinically important long-acting β-agonist, formoterol, was as effective as epinephrine in potentiating IL-13 induced MUC5AC transcription. IL-13 induced mucin production in the presence of epinephrine was significantly reduced by treatment with selective inhibitors of ERK1/2 (FR180204), p38 (SB203580) and JNK (SP600125). Replacement of epinephrine with forskolin + IBMX resulted in a marked increase in mucin production in NHBE cells in response to IL-13, and treatment with the inhibitory cAMP analogue Rp-cAMPS decreased mucin levels induced by epinephrine + IL-13. Our findings suggest that β2AR signaling is required for mucin production in response to IL-13, and that mitogen activated protein kinases and cAMP are necessary for this effect. These data lend support to the notion that β2AR-agonists may contribute to asthma exacerbations by increasing mucin production via activation of β2ARs on epithelial cells.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Adrenergic beta-2 Receptor Agonists / pharmacology
  • Animals
  • Bronchi / cytology*
  • Cattle
  • Cyclic AMP / pharmacology
  • Cyclic AMP-Dependent Protein Kinases / metabolism
  • Epinephrine / pharmacology*
  • Epithelial Cells / drug effects
  • Epithelial Cells / enzymology
  • Epithelial Cells / metabolism*
  • Humans
  • Interleukin-13 / pharmacology*
  • MAP Kinase Signaling System / drug effects
  • Mucin 5AC / metabolism*
  • Receptors, Adrenergic, beta-2 / metabolism*

Substances

  • Adrenergic beta-2 Receptor Agonists
  • Interleukin-13
  • MUC5AC protein, human
  • Mucin 5AC
  • Receptors, Adrenergic, beta-2
  • Cyclic AMP
  • Cyclic AMP-Dependent Protein Kinases
  • Epinephrine