Experimental mouse model of bronchial asthma induced by house dust mite Dermatophagoides pteronyssinus allergenic extract

Abstract

The purpose of this study was to develop a mouse model of asthma (MMA) using house dust mite Dermatophagoides pteronyssinus (Der p) extract. Methods. BALB/c mice were i.p. immunized with different doses of Der p lyophilized extract three times in three week interval in the mixture with Al(OH)3. 8 weeks after the final immunization mice were challenged with Der p during five consecutive days by intranasal applications (INA) or aerosol administration (AA). All mice were divided into 5 experimental groups: group 1 was immunized with 50 ^g/mouse of Der p (in protein equivalent) in the mixture with 2 mg/mouse Al(OH)3 and challenged by INA; group 2 was immunized in the same way and challenged by AA; group 3 was immunized with 100 ^g/mouse Der p in the mixture with 2 mg/mouse of Al(OH)3 and challenged by INA; group was immunized in the same way and challenged by AA; group 5 (negative control) was immunized and challenged with saline. 24 hours after the last challenge airway hyperresponsiveness (AHR) to different concentrations of metha-choline was evaluated in all groups by whole-body plethysmography. 48 hours after the last challenge in all groups blood was collected for differential cell count, brochoalveolar lavage fluid (BALF) was sampled for the determination of inflammatory cells and lungs were removed for histological analysis. Histopathological changes in lungs (allergic inflammation) were graded according to semi-quantitative scoring system. Anti-Der p IgE, IgG1 and IgG2a antibodies in individual sera samples were detected by ELISA seven days after the last immunization and 48 hours after the challenge. Results. The levels of anti-Der p IgE antibodies in groups 1-4 before as well as after the challenge were substantially higher than that of in the group 5 (negative control). The highest level of serum Der p-specific IgE antibodies was observed in the group 2. The levels of anti-Der p IgG1 and IgG2a antibodies in the groups 1-4 during all periods of observation were higher than that of group 5 (negative control). At the same time the maximal levels of anti-Der p IgG1 and IgG2a antibodies were observed in group 3 both after immunization and after challenge. The maximum of AHR was observed in the groups 1 and 3 challenged by INA. Analysis of cell composition in BALF demonstrated significant elevated number of eosinophils in group 3 in comparison with group 5 (negative control) and other experimental groups. Regarding peripheral blood leukocyte count we observed decreasing of band neutrophils in group 4 and increasing of segmented neutrophils in groups 1 and 3 in compare to group 5 (negative control). In group 1 we found statistically significant decreasing of lymphocytes and increasing of eosinophils in compare to negative control group 5. Histological picture of general allergic inflammation in lungs as well as peribronchial and perivascular infiltration with inflammatory cells were the most noticeable (according to score system) in group 3 in comparison with negative control group and other experimental groups. Conclusion. Data obtained indicate that immunization (sensitization) of mice with Der p in a dose 100 μg/mouse together with Al(OH)3 and challenge with Der p by mean of intranasal applications is a suitable approach for modeling of mouse allergic asthma.