Establishment of airway eosinophilic bronchitis mouse model without hyperresponsiveness by ovalbumin

Eosinophilic bronchitis (EB) is a useful tool for studying airway hyperresponsiveness (AHR), but an exact EB animal model is lacking. Our objective was to establish an EB mouse model using ovalbumin (OVA). Mice were divided into asthma, normal saline (NS) control and three model groups. Asthma mice were challenged intranasally with 200 mu g OVA. Model groups were challenged with one of the three OVA doses (10, 20 or 100 mu g), and NS control mice received normal saline. Changes in lung resistance (R-L), serum OVA-specific immunoglobulin-E (IgE) and differential inflammatory cell counts in bronchoalveolar lavage fluid (BALF) were determined after exposure to increasing doses of methacholine (MCh). Lung histological sections were examined for inflammatory infiltration. R-L in the 10-mu g OVA-challenged model group was not significantly different compared with the NS group at any MCh concentration but was significantly different compared with the asthma group (P < 0.01). R-L in the other two model groups was intermediate between the asthma and NS groups. Serum OVA-specific IgE and eosinophils in BALF were increased significantly in all model and asthma groups compared with the NS group, but no significant differences were observed between model and asthma groups. Inflammatory cells were seen around bronchioles and capillaries in model and asthma groups but not the NS group. A mouse model of EB without AHR can be established by 10 mu g OVA challenge and provides a useful tool for studying AHR mechanisms.