Mechanisms of asthma exacerbation
The clinical characteristics of an asthma exacerbation include symptoms of dyspnea, chest tightness and mucus hypersecretion. These characteristics represent the clinical expression of airway inflammation and changes in airway structural cells that are quite complex and not fully understood. Surprisingly few mechanistically oriented studies in human asthma have attempted to unravel this complexity. From available data, it is clear that intense airway inflammation is characteristic of asthma exacerbation and that changes occur in structural airway cells such as smooth muscle cells, mucous cells and cells in the bronchial microvasculature. The net effect of this pathology is airflow obstruction occurring not just because of concentric smooth muscle contraction, but also because of edema of the airway wall and mucous plugging of the airway lumen.