SELECTED ARTICLES FROM THE RECENT LITERATURE 2005
9/23/05
Airway remodeling and asthma severity
Summary
Background - There has been increasing interest in and investigation of airway remodeling (AR) in chronic asthma characterized by epithelial detachment, an increase in airway smooth muscle (ASM) mass and sub epithelial fibrosis. It has been postulated that AR is responsible for irreversible pathology and subsequent difficulties in the control of some cases of chronic asthma. However, the exact relationship of AR to pulmonary function is not well defined.
Findings - Pepe et al from the Meakins-Christie Laboratories compared AR as defined by morphometry of bronchial biopsies with pulmonary function in 28 persistent asthmatics defined as severe or moderate by clinical criteria. They found that increased ASM mass and shorter distance from ASM to epithelium were selectively seen in bronchial tissues of the severe asthmatics (p<0.001). There was increased presence of IL-8 and eotoxin in the in the ASM of the severe asthmatics. These findings support the contention that key structural changes in ASM distinguish severe from moderate chronic asthma, contributing to the difficulty in controlling adequate control in some severe asthmatics.
Reference
J Allergy Clin Immunol 2005;116:544-9
Editor's Comments
Some decades ago, investigators of the pathogenesis of asthma focused mainly on ASM abnormalities, considering that airway obstruction was due mainly to ASM spasm/hypertrophy. More recently the emphasis has been on inflammatory changes in the bronchial mucosa as the major mechanism underlying airway obstruction in chronic asthma. It may well be that both airway inflammation and ASM hypertrophy (possibly inter related) play pathogenic roles.
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