Mite-induced allergic airway inflammation in guinea pigs

Background: Mites are the most common aeroallergen in human allergic asthma. However, no animal model of mite-induced allergic airway inflammation has been reported before. In this study, an animal model of mite-induced allergic airway inflammation in guinea pigs was developed. Methods: Firstly, we found that two intraperitoneal injections of 100 mu g crude mite extract (CME), but not multiple aerosol inhalations of 10 mg/ml CME, can cause sensitization in guinea pigs. The sensitization to mites was confirmed by the measurement of serum antimite antibody titer and the detection of anaphylactic bronchoconstriction after intravenous injection of CME solution. Then, single or multiple aerosol challenges with different concentrations (8, 4 or 1 mg/ml) of CME in these sensitized animals were performed. The total white cell and differential counts in the bronchoalveolar lavage (BAL) fluids were studied at different time intervals after challenge in different animals, and tracheal pathology was performed to detect the allergic airway inflammation. For comparison with the study in animals treated with CME, a BAL study in animals treated with ovalbumin was also performed. Results: The inhalation challenge of CME aerosol in sensitized animals caused prolonged eosinophilia in BAL fluid which persisted for at least 7 days after single challenge. Neither inhalation challenge at higher concentrations of CME aerosol nor repeated inhalation challenges increased the degree of eosinophilia in BAL fluid compared to a single challenge. Using the same procedures, we also found that the mite model caused more eosinophilia in BAL fluid than did ovalbumin. Conclusion: This is the first report of an animal model of mite-induced allergic airway inflammation in guinea pigs which can provide us with a useful model to study airway inflammation of mite-induced asthma in humans.