Zileuton Reduces Respiratory Illness and Lung Inflammation, during Respiratory Syncytial Virus Infection, in Mice

To determine the role of leukotrienes in a mouse model of respiratory syncytial virus (RSV) infection, we correlated the quantity of leukotrienes in lung lavage fluids of infected mice with respiratory rates and measures of outflow obstruction and then determined the effects of the leukotriene inhibitor zileuton on clinical features and lung function. Concentrations of leukotrienes were correlated with both increasing respiratory rates and the degree of prolongation of expiratory time. Administration of zileuton 1 day before infection and through day 5 after infection markedly reversed airway constriction, reduced numbers of inflammatory cells in the lung, and prevented the weight loss associated with infection. Leukotrienes appear to contribute substantially to the pathogenesis of RSV-related disease.