Differential effects of allergen challenge on large and small airway reactivity in mice

PLoS One. 2013 Sep 6;8(9):e74101. doi: 10.1371/journal.pone.0074101. eCollection 2013.

Abstract

The relative contributions of large and small airways to hyperresponsiveness in asthma have yet to be fully assessed. This study used a mouse model of chronic allergic airways disease to induce inflammation and remodelling and determine whether in vivo hyperresponsiveness to methacholine is consistent with in vitro reactivity of trachea and small airways. Balb/C mice were sensitised (days 0, 14) and challenged (3 times/week, 6 weeks) with ovalbumin. Airway reactivity was compared with saline-challenged controls in vivo assessing whole lung resistance, and in vitro measuring the force of tracheal contraction and the magnitude/rate of small airway narrowing within lung slices. Increased airway inflammation, epithelial remodelling and fibrosis were evident following allergen challenge. In vivo hyperresponsiveness to methacholine was maintained in isolated trachea. In contrast, methacholine induced slower narrowing, with reduced potency in small airways compared to controls. In vitro incubation with IL-1/TNFα did not alter reactivity. The hyporesponsiveness to methacholine in small airways within lung slices following chronic ovalbumin challenge was unexpected, given hyperresponsiveness to the same agonist both in vivo and in vitro in tracheal preparations. This finding may reflect the altered interactions of small airways with surrounding parenchymal tissue after allergen challenge to oppose airway narrowing and closure.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Airway Remodeling
  • Allergens / immunology*
  • Animals
  • Antibody Specificity / immunology
  • Bronchial Hyperreactivity / immunology*
  • Bronchial Hyperreactivity / metabolism
  • Bronchial Hyperreactivity / pathology
  • Bronchial Provocation Tests
  • Calcium / metabolism
  • Dinoprostone / metabolism
  • Disease Models, Animal
  • Female
  • Immunoglobulin E / immunology
  • Inflammation / immunology
  • Inflammation / metabolism
  • Inflammation / pathology
  • Methacholine Chloride / administration & dosage
  • Mice
  • Ovalbumin / immunology

Substances

  • Allergens
  • Methacholine Chloride
  • Immunoglobulin E
  • Ovalbumin
  • Dinoprostone
  • Calcium

Grants and funding

This work was supported by the University of Melbourne Faculty Research Grant Scheme and NHMRC Project Grants (509239, 1041575). CD is supported by an Australian Postgraduate Award. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.