Inhibitory effect of inhaled FK-506 on increased bronchial responsiveness and eosinophil infiltration in the airway mucosa]

We examined the effects of inhaled FK-506, a potent immunosuppressive agent, on increased bronchial responsiveness to acetylcholine and on eosinophil infiltration in a guinea pig models of asthma. The guinea pigs were sensitized by repeated inhalation of ovalbumin (OA). Twenty four hours after antigen challenge, bronchial responsiveness to acetylcholine significantly increased and a marked accumulation of eosinophils in the airways was observed. However, when the guinea pigs were treated with aerosolized FK (10 mg/ml) for 5 min per day for 6 successive days before antigen challenge, the increase in bronchial responsiveness was significantly suppressed and the eosinophil accumulation was strikingly reduced. Since inhaled FK significantly suppressed these responses, there is a possibility that inhaled FK may be a useful therapy for patients with chronic bronchial asthma in the future.