Oxygen radicals in inflammation and allergy related to viral infections

Oxygen radicals including superoxide anion (O(2)(-)) and nitric oxide (NO) are involved in a variety of inflammatory diseases induced by viral infection. In this review, we focus on the role of oxygen radicals in allergic inflammation such as bronchial asthma induced by viral infection--specifically, with respiratory syncytial virus (RSV). This infection in early childhood is a risk factor for development of wheezing, significant decreases in pulmonary function, and increases in airway reactivity. RSV infection also exacerbates recurrent wheezing attacks in patients with established asthma. Recently, we have demonstrated that RSV enhanced superoxide production by human eosinophils stimulated with a lipid mediator such as platelet-activating factor. This response depends on a beta2 integrin, alphaMbeta2, which is critical for eosinophil effector functions. Our results suggest that eosinophils and their products promote RSV-induced airway inflammation in asthma. Close delineation of the mechanism by which RSV enhances eosinophilic inflammation in asthma should yield clues to more effective therapy.