Abstract
Asthma is a disease of usually reversible airways obstruction that has prominent inflammation of the mucosa as an underlying feature. It is a disease of varying severity, with some individuals suffering from only occasional symptoms and others having daily symptoms and requiring large doses of inhaled and oral corticosteroids. Although the different forms of asthma have some common pathological features, the extent of change varies from mild to severe forms. The only cell type that has been widely correlated with disease severity has been the eosinophils, but it is evident that altered function and responsiveness of T cells to steroids plays a key role as a determinant of asthma severity. More recently, attention has focused on restructuring of the airways, which results in, or possibly develops in parallel with, inflammation. This restructuring consists of changes throughout the bronchial wall, beginning with changes in the epithelium, increased collagen deposition, increased microvasculature, hypertrophy and hyperplasia of submucosal glands, goblet metaplasia within the epithelium, hypertrophy and hyperplasia of smooth muscle and, finally, poorly defined changes in the adventitia. Novel treatments have been, and continue to be, developed to target specific components of inflammation and remodeling. However, to date, none has lead to a marked improvement in disease control and further efforts are needed to better understand the mechanisms of asthma, in particular those that are not responsive to corticosteroids.
