Abstract:

Objective To investigate the alterations of signal transducer and activator of transcription factor 6（STAT6） signaling in a mouse model of asthma receiving treatment with Dermatophagoides pteronyssinus group 2 allergen（Der p 2） T cell fusion epitope and the mechanisms of the specific immunotherapy. Methods Thirty mice were randomly divided into three groups by the random number table method: the asthma group, the treatment group receiving immunotherapy with Der p 2 T cell fusion epitope, and the negative control group （PBS group）（n = 10 in each group）. Mice in the asthma and the treatment groups received intraperitoneal （i.p.） injection of 100 μl Der p 2 solution [PBS containing 100 μg/ml Der p 2 and 2% Al（OH）₃] on days 0, 7 and 14, respetively, while mice in the PBS group received same volume of PBS containing 2% Al（OH）₃. From day 21, 30-min steam inhalation of 0.5 μg/ml Der p 2 was applied to the asthma and treatment groups （once daily for 7 successive days）, and the PBS group inhaled same volume of PBS. From day 25 to day 27, the mice in the treatment group received i.p. injection of 200 μl of Der p 2 T cell fusion epitope （100 μg/ml） while the PBS and the asthma groups received the same volume of PBS. Mice were sacrificed at 24 h after the last inhalation, the bronchoalveolar lavage fluid （BALF） collected, and the total protein was extracted from the lung tissue. The levels of IFN-γ, IL-4 and IL-13 in BALF were determined by ELISA. The expression of STAT6 and phosphorylated STAT6 （p-STAT6） in the lung tissue was detected by Western blotting. Data were analyzed with the one-way variance analysis （ANOVA） method. Results The level of IFN-γ in the treatment group[（234.40 ± 24.46） pg/ml] was significantly higher than that in the asthma group[（155.80 ± 20.53） pg/ml]（P < 0.01）. The levels of IL-4 and IL-13 in the treatment group [（30.00 ± 5.50） pg/ml and （174.50 ± 25.99） pg/ml, respectively] were both significantly lower than those in the asthma group[（53.28 ± 8.26） pg/ml and （308.10 ± 28.32） pg/ml, respectively]（P < 0.01）. Similarly, the levels of STAT6 and p-STAT6 in the treatment group（0.803 ± 0.221 and 0.966 ± 0.323, respectively） were both significantly lower than those in the asthma group （1.669 ± 0.296 and 1.735 ± 0.298, respectively）（P < 0.01）. Conclusion The Der p 2 T cell fusion epitope may function through inhibiting STAT6 to treat asthma in mice.

Key words: Dermatophagoides pteronyssinus, Specific immunotherapy, T cell epitope, Signal transducer and activator of transcription factor 6