Pathology of asthma and its clinical implications

Although detailed histopathologic studies have described the inflammatory processes present in fatal asthma, until recently the pathology of less severe forms of the disease has been less well understood. Now a series of important studies has extended our understanding of the pathophysiology of mild asthma. Studies that examine sputum or fluid obtained by bronchoalveolar lavage from mildly asthmatic subjects revealed findings consistent with an active inflammatory process within the airways. The histopathologic examination of endobronchial biopsy specimens from stable asthmatic patients has shown that inflammatory cell infiltration of the mucosa is a distinctive feature of mildly asthmatic subjects requiring only intermittent inhaled beta-agonist therapy. These studies have also shown that marked tissue disruption may occur early in the natural history of mild asthma. These investigations have demonstrated that asthma is a disease characterized by acute and chronic inflammatory changes within the airways and that in many respects the histopathologic features of mild allergic asthma are similar to those observed in fatal asthma. The therapeutic implications of these findings are that management of mild asthma should be directed toward resolving this inflammatory process. There is now sufficient evidence to suggest that anti-inflammatory drugs such as cromolyn sodium, inhaled corticosteroids, and nedocromil sodium be used earlier in the course of the disease and that the use of these therapeutic agents should not be limited to patients with severe forms of asthma. This may be particularly important in view of the increasing awareness of the potential problems associated with the overreliance on beta-agonist therapy in patients with asthma.