Background: IL-5 is central to the pathogenesis of airway eosinophilic inflammation and hyperresponsiveness associated with both atopic and nonatopic asthma. The therapeutic potential of IL-5 antagonists in asthma is supported by the inhibition of airway eosinophilia and hyperresponsiveness in animal models receiving neutralizing anti-IL-5 mAbs intravenously or intraperitoneally.
Objective: The purpose of this study was to test the hypothesis that mAbs against IL-5 delivered by way of the respiratory tract are as effective as those delivered intraperitoneally in diminishing the pulmonary eosinophilic inflammation and airway hyperresponsiveness in a murine model of ovalbumin-induced asthma.
Methods: Ovalbumin-sensitized Balb/c mice were given an anti-IL-5 mAb delivered intranasally or an isotype-matched control mAb delivered intranasally before respiratory challenge with ovalbumin. Outcome variables included respiratory system resistance responses to methacholine, bronchoalveolar lavage fluid cellularity, and lung histopathology.
Results: Anti-IL-5 mAbs administered intranasally to ovalbumin-sensitized and challenged mice significantly decreased eosinophil counts in bronchoalveolar lavage fluid and lung tissue and significantly reduced airway hyperresponsiveness relative to ovalbumin-sensitized and challenged mice that received either no mAb treatment or an isotype-matched control mAb. Similar results were obtained when an anti-IL-5 mAb was given intraperitoneally.
Conclusion: This is the first study to demonstrate that delivery of anti-IL-5 mAbs into the respiratory tract is efficacious in attenuating the asthma phenotype in a murine model. These results provide impetus for the development of inhaled IL-5 antagonists for the treatment of human asthma.