Remodeling Asthma Patients’ Airways

Reported May 27, 2011

(Ivanhoe Newswire) -- Asthma is a common chronic respiratory condition characterized clinically by an excessive tendency toward reversible airway narrowing. Scientists believe that the airway narrowing induced by allergen exposure in patients with asthma may in itself be a sufficient stimulus for the development of airway remodeling, and that such remodeling is not solely dependent on induced recruitment of airway eosinophils which trigger airway remodeling as well.

To test this hypothesis, we performed repeated challenges with exposure to either allergen (to induce bronchoconstriction with airway eosinophil recruitment) or methacholine (to induce bronchoconstriction alone) in volunteers who had mild atopic asthma. Two additional groups of volunteers with asthma served as controls, undergoing repeated challenges with either saline placebo (to control for the challenge procedures) or methacholine after they had received albuterol to prevent. The effect of these challenges on the airway was evaluated by assessing changes in markers of airway remodeling in endobronchial tissue before and after the challenge.

This study shows that repeated bronchoconstriction in asthma promotes airway remodeling. The changes were evident 4 days after repeated airway challenges and were independent of the stimulus causing the bronchoconstriction. Furthermore, they appear to be independent of eosinophil recruitment into the airways, since, on the basis of the specific markers we chose, the remodeling changes evident after the allergen challenge (which induced airway eosinophil recruitment) were similar to those seen after the methacholine challenge (which did not induce such recruitment).

These findings have implications for the management of asthma, since airway remodeling has been linked to a decline in lung function and the loss of bronchodilator reversibility.

SOURCE: New England Journal of Medicine, May 2011.