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Journal of Allergy
Volume 2012 (2012), Article ID 593784, 9 pages
http://dx.doi.org/10.1155/2012/593784
Review Article

Airway Smooth Muscle as a Target in Asthma and the Beneficial Effects of Bronchial Thermoplasty

Firestone Institute for Respiratory Health, St. Joseph’s Hospital and Department of Medicine, McMaster University, Hamilton, ON, Canada L8N 3Z5

Received 4 July 2012; Accepted 1 August 2012

Academic Editor: Ynuk Bossé

Copyright © 2012 Luke J. Janssen. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Airflow within the airways is determined directly by the lumenal area of that airway. In this paper, we consider several factors which can reduce airway lumenal area, including thickening and/or active constriction of the airway smooth muscle (ASM). The latter cell type can also contribute in part to inflammation, another feature of asthma, through its ability to take on a synthetic/secretory phenotype. The ASM therefore becomes a strategically important target in the treatment of asthma, given these key contributions to the pathophysiology of that disease. Pharmacological approaches have been developed to elicit relaxation of the ASM, but these are not always effective in all patients, nor do they address the long-term structural changes which impinge on the airway lumen. The recent discovery that thermal energy can be used to ablate smooth muscle has led to the development of a novel physical intervention—bronchial thermoplasty—in the treatment of asthma. Here, we review the evolution of this novel approach, consider some of the possible mechanisms that account for its salutary effects, and pose new questions which may lead to even better therapies for asthma.