Chronic IL9 and IL-13 exposure leads to an altered differentiation of ciliated cells in a well-differentiated paediatric bronchial epithelial cell model

PLoS One. 2013 May 9;8(5):e61023. doi: 10.1371/journal.pone.0061023. Print 2013.

Abstract

Asthma is a chronic inflammatory disease characterised by airways remodelling. In mouse models IL-9 and IL-13 have been implicated in airways remodelling including mucus hypersecretion and goblet cell hyperplasia. Their role, especially that of IL-9, has been much less studied in authentic human ex vivo models of the bronchial epithelium from normal and asthmatic children. We assessed the effects of IL-9, IL-13 and an IL-9/IL-13 combination, during differentiation of bronchial epithelial cells from normal (n = 6) and asthmatic (n = 8) children. Cultures were analysed for morphological markers and factors associated with altered differentiation (MUC5AC, SPDEF and MMP-7). IL-9, IL-9/IL-13 combination and IL-13 stimulated bronchial epithelial cells from normal children had fewer ciliated cells [14.8% (SD 8.9), p = 0.048, 12.4 (SD 6.1), p = 0.016 and 7.3% (SD 6.6), p = 0.031] respectively compared with unstimulated [(21.4% (SD 9.6)]. IL-9 stimulation had no effect on goblet cell number in either group whereas IL-9/IL-13 combination and IL-13 significantly increased goblet cell number [24.8% (SD 8.8), p = 0.02), 32.9% (SD 8.6), p = 0.007] compared with unstimulated normal bronchial cells [(18.6% (SD 6.2)]. All stimulations increased MUC5AC mRNA in bronchial epithelial cells from normal children and increased MUC5AC mucin secretion. MMP-7 localisation was dysregulated in normal bronchial epithelium stimulated with Th2 cytokines which resembled the unstimulated bronchial epithelium of asthmatic children. All stimulations resulted in a significant reduction in transepithelial electrical resistance values over time suggesting a role in altered tight junction formation. We conclude that IL-9 does not increase goblet cell numbers in bronchial epithelial cell cultures from normal or asthmatic children. IL-9 and IL-13 alone and in combination, reduce ciliated cell numbers and transepithelial electrical resistance during differentiation of normal epithelium, which clinically could inhibit mucociliary clearance and drive an altered repair mechanism. This suggests an alternative role for IL-9 in airways remodelling and reaffirms IL-9 as a potential therapeutic target.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Asthma / genetics
  • Asthma / metabolism
  • Asthma / pathology
  • Bronchi / cytology
  • Cell Count
  • Cell Differentiation / drug effects*
  • Cells, Cultured
  • Child
  • Child, Preschool
  • Cilia
  • Drug Synergism
  • Electric Impedance
  • Epithelial Cells / cytology
  • Epithelial Cells / drug effects*
  • Epithelial Cells / metabolism
  • Gene Expression / drug effects
  • Goblet Cells / cytology
  • Goblet Cells / drug effects
  • Goblet Cells / metabolism
  • Humans
  • Immunohistochemistry
  • Infant
  • Interleukin-13 / metabolism
  • Interleukin-13 / pharmacology*
  • Interleukin-9 / metabolism
  • Interleukin-9 / pharmacology*
  • Matrix Metalloproteinase 7 / genetics
  • Matrix Metalloproteinase 7 / metabolism
  • Microscopy, Confocal
  • Mucin 5AC / genetics
  • Mucin 5AC / metabolism
  • Proto-Oncogene Proteins c-ets / genetics
  • Proto-Oncogene Proteins c-ets / metabolism
  • Reverse Transcriptase Polymerase Chain Reaction

Substances

  • Interleukin-13
  • Interleukin-9
  • MUC5AC protein, human
  • Mucin 5AC
  • Proto-Oncogene Proteins c-ets
  • SPDEF protein, human
  • MMP7 protein, human
  • Matrix Metalloproteinase 7

Grants and funding

This work was supported by the Northern Ireland Chest Heart and Stroke Association (grant number 200546), The Royal Belfast Hospital for Sick Children and The Irish Thoracic Society Boehringer Ingleheim Research Fellowship. The funders had no role in the study design, data collection and analysis, decision to publish, or preparation of the manuscript.