Allergen-induced changes in airway responsiveness are not related to indices of airway edema

R. Stokes Peebles, Elizabeth M. Wagner, Mark C. Liu, David Proud, Robert G. Hamilton, Alkis Togias

Research output: Contribution to journalArticle

Abstract

Background: The mechanisms behind airway hyperresponsiveness in asthma are unknown. Airway wall edema has been proposed as one possible culprit of this phenomenon. Objective: To test the hypothesis that airway edema may be the cause of allergen-induced increases in airway responsiveness in asthma, this trial aimed at determining the relationship between allergen-induced changes in airway responsiveness to inhaled methacholine and indirect indices of edema, namely peripheral airway resistance and the levels of the plasma protein fibrinogen in bronchoalveolar lavage (BAL) fluids. Methods: Twenty-six atopic individuals with mild asthma were subjected to bronchoscopy at baseline and 28 hours after allergen inhalation. Before each bronchoscopy, methacholine bronchoprovocation was performed. During bronchoscopy, peripheral airway resistance measurements were obtained by wedged bronchoscopy. BAL fluids were analyzed for fibrinogen, as well as for eosinophilic cationic protein. Cytology was performed, and cytokine gene expression was assessed with competitive reverse transcriptase PCR from cell pellets. Results: A significant increase in airway responsiveness to methacholine was recorded after allergen, but this did not correlate with changes in peripheral airway resistance (which was not affected) or with BAL fibrinogen (which decreased after allergen). Other BAL outcomes confirmed that airway inflammation was produced and was characterized by a TH2 cytokine pattern. Conclusions: Airway responsiveness in asthma increases after exposure to allergen in the absence of increased indirect indices of edema. The role of edema in this phenomenon should therefore be tested more vigorously.

Original languageEnglish (US)
Pages (from-to)805-811
Number of pages7
JournalJournal of Allergy and Clinical Immunology
Volume107
Issue number5 SUPPL.
DOIs
StatePublished - May 2001

Keywords

  • Allergen challenge
  • Bronchoalveolar lavage
  • Eosinophilic cationic protein
  • Eosinophils
  • Fibrinogen
  • Inflammation
  • Methacholine
  • Peripheral airway resistance

ASJC Scopus subject areas

  • Immunology and Allergy
  • Immunology

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