[A specific immune therapeutic effect of Der p2 T cell epitope vaccine on asthma mice]

To investigate the specific immune therapeutic effect of the T cell fusion peptide vaccine from group II allergens from Dermatophagoides pteronyssinus (Der p2).

Thirty mice were randomly divided into three groups, namely a negative control group (a PBS group), positive control group (an asthma group) and protein Der p2 T cell fusion epitope for specific immunotherapy (SIT) group (a Der p2 T group). The extract of house dust mites (HDM) was used to establish the asthmatic models in BALB/c mice, and the PBS group was always used with PBS buffer. Thirty minutes before spray inhalation from 25 to 27 days, the mice of the Der p2 T group were respectively injected subcutaneously with the therapeutic proteins for SIT, then the serum and bronchoalveolar lavage fluid (BALF) were collected. ELISA was used to assay the levels of IFN-γ, IL-4, and IL-13 in BALF, as well as serum levels of specific IgE and IgG2a. The lung tissue sections were stained with haematoxylin and eosin (H&E) for pathological examinations.

The ELISA detection revealed that the number of eosinophil in BALF of the asthmatic mice was (5.57 ± 0.64)×10⁵/ml, which was significantly higher than that in the PBS group [(0.50 ±0.30)×10⁵/ml, P < 0.01], the number of eosinophil in the Der p2 T immunotherapy group decreased significantly [(3.45 ± 0.36)×10⁵/ml, P < 0.01]. The content of IFN-γ in the PBS group, asthma group and Der p2 T group were (267.00 ± 21.98), (155.80 ± 20.53) pg/ml and (234.40 ± 24.46) pg/ml respectively. Compared with the asthma group, the mice with Der p2 T vaccine specific immune treatment produced a high level of IFN-γ (P < 0.01). The content of IL-4 in the PBS group, asthma group and Der p2 T group were (23.40 ± 5.96), (53.28 ± 8.26) pg/ml and (30.00 ± 5.50) pg/ml respectively. Compared with the asthma group, the content of IL-4 in the mice of the Der p2 T treatment group was significantly lower (P < 0.01). Compared with the asthma group [(308.10 ± 28.32) pg/ml], the content of IL-13 in BALF of the mice in the Der p2 T treatment group was significantly decreased, which was [(174.50 ± 25.99) pg/ml, P < 0.01]. The content of IL-13 in the PBS group was (95.99 ± 31.14) pg/ml. The lung tissue sections showed that the lung inflammation in the p2 T Der group was significantly less than that in the asthma group, and the inflammatory cell infiltration was significantly decreased, and airway epithelial construction remodeled.

The Der p2 T cell fusion epitope, which is as vaccines for specific immunotherapy with asthma models, can alleviate effectively allergic inflammation of airway and lung in the mice, and it may be used as a candidate vaccine for asthma.