Frequent Bronchoconstriction Tied to Airway Remodeling

Repeated experimentally induced bronchoconstriction may lead to airway change

THURSDAY, May 26 (HealthDay News) -- Experimentally induced bronchoconstriction may promote airway remodeling in patients with asthma, according to a study published in the May 26 issue of the New England Journal of Medicine.

Christopher L. Grainge, Ph.D., from the University of Southampton School of Medicine in the United Kingdom, and colleagues evaluated the effect of repeated experimentally induced bronchoconstriction on structural changes in the airway of 48 patients with asthma. Participants were randomized to one of four inhalation challenges with an inhaled agent presented three times at 48-hour intervals. Inhaling agents included a dust-mite allergen (induces eosinophilic inflammation and bronchoconstriction), and methacholine (induces only bronchoconstriction), and controls were given saline or albuterol followed by methacholine. Bronchial biopsy specimens were evaluated before and four days after the challenges.

The investigators found similar levels of bronchoconstriction in the allergen and methacholine groups. Airway remodeling was not seen in the control groups, but was seen in both the allergen and methacholine groups, and eosinophilic inflammation increased only in the allergen group. Thickness of the sub-epithelial collagen band and periodic acid-schiff staining of epithelium increased significantly in the allergen and methacholine groups, compared to the two control groups.

"This study thus provides evidence that bronchoconstriction induces epithelial stress and initiates a tissue response that leads to structural airway changes," the authors write.

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