Interleukin-9 promotes allergen-induced eosinophilic inflammation and airway hyperresponsiveness in transgenic mice

Human atopic asthma is a complex heritable inflammatory disorder of the air ways associated with clinical signs of allergic inflammation and airway hyp erresponsiveness. Recent studies demonstrate that the degree of airway resp onsiveness is strongly associated with interleukin (IL)-9 expression in mur ine lung. To investigate the contribution of IL-9 to airway hyperresponsive ness, and to explore directly its relationship to airway inflammation, we s tudied transgenic mice overexpressing IL-9. In this report we show that IL- 9 transgenic mice (FVB/N-TG5), in comparison with FVB/NJ mice, display sign ificantly enhanced eosinophilic airway inflammation, elevated serum total i mmunoglobulin E, and airway hyperresponsiveness following lung challenge wi th a natural antigen (Aspergillus fumigatus). These data support a central role for IL-9 in the complex pathogenesis of allergic inflammation.