Asthma is considered a common chronic disorder of the airways that is complex and heterogeneous. Common characteristics include variable airflow obstruction, airway hyperresponsiveness, and underlying inflammation.1,2
Persistent changes in airway structure occur in some patients with asthma. These include subbasement fibrosis, mucus hypersecretion, injury to epithelial cells, smooth muscle hypertrophy, and angiogenesis. Compare the differences between a normal airway and one with asthma in the diagram below.1
Reprinted from Holgate ST, Sly PD. Asthma pathogenesis. In: Adkinson Jr NF, Bochner BS, Burks AW, et al, eds. Middleton's Allergy Principles and Practice. 8th ed. Philadelphia, PA: Elsevier Saunders; 2014:812-842.
Remodeling is defined as structural changes in the airway walls that stem from inflammatory changes.5
In severe asthma, exaggerated airway remodeling may be seen. This remodeling includes subepithelial thickening of the bronchial reticular layer and in the small airways.3
In time, remodeling can compromise the efficacy of bronchodilators and oral corticosteroids and cause more severe exacerbations.3
References: 1. National Institutes of Health. Section 2, Definition, pathophysiology and pathogenesis of asthma, and natural history of asthma. In: Expert Panel Report 3: Guidelines for the Diagnosis and Management of Asthma. Bethesda, MD: National Heart, Lung, and Blood Institute (US); 2007. www.ncbi.nlm.nih.gov/books/NBK7223/. Accessed June 22, 2017. 2. Global Initiative for Asthma. Global strategy for asthma management and prevention, 2017. www.ginasthma.org. Accessed July 26, 2017. 3. Chung KF, Wenzel SE, Brozek JL, et al. International ERS/ATS guidelines on definition, evaluation and treatment of severe asthma. Eur Respir J. 2014;43(2):343-373. 4. Holgate ST, Sly PD. Asthma pathogenesis. In: Adkinson Jr NF, Bochner BS, Burks AW, et al, eds. Middleton's Allergy Principles and Practice. 8th ed. Philadelphia, PA: Elsevier Saunders; 2014:812-842. 5. Kumar RK, Jeffery PK. Pathology of asthma. In: Adkinson Jr NF, Bochner BS, Burks AW, et al, eds. Middleton’s Allergy Principles and Practice. 8th ed. Philadelphia, PA: Elsevier Saunders; 2014:986-999. 6. Chae EJ, Kim T-B, Cho YS, et al. Airway measurement for airway remodeling defined by post-bronchodilator FEV1/FVC in asthma: investigation using inspiration-expiration computed tomography. Allergy Asthma Immunol Res. 2011;3(2):111-117.