[Immunotherapeutic Effect of Dermatophagoides pteronyssinus Group 1 Allergen T Cell Epitope Peptide Against Allergic Asthma in Mice].

Objective: To study the specific immunotherapeutic effect of Dermatophagoides pteronyssinus group 1 major allergen T-cell fusion epitope peptide vaccine TAT-IhC-DPTCE against allergic asthma.

Methods: One hundred and twenty SPF-grade BALB/c mice were randomized into PBS group (group A), asthma group （group B）, and immune treatment groups respectively receiving intraperitoneal (i.p.) injections of ProDer p 1 allergen (group C), DPTCE （group D）, TAT-DPTCE (group E) or TAT-IhC-DPTCE (group F) （n=20 in each group）. In detail, PBS （group A） or allergen extract derived from Dermatophagoides pteronyssinus （groups B-F, 10 μg） was intraperitoneally injected on days 0, 7 and 14, and was continued by aerosol inhalation from day 21 for 7 consecutive days （0.5 μg/ml, once/day, 30 min each time）. The mice in groups C-F received i.p. injections of 100 μg/ml ProDer p 1, DPTCE, TAT-DPTCE and TAT-IhC-DPTCE respectively 30 min prior to inhalation challenge on days 25-27 as a specific immunotherapy, while those in groups A and B received 200 μl PBS. Twenty-four hours after the last inhalation challenge, all the mice were sacrificed. The lung histopathological changes were examined by HE staining. The levels of IFN-γ, IL-13, IL-10 and TGF-β in the bronchoalveolar lavage fluid (BALF) was determined with ELISA, and eosinophils in the BALF were counted (n=20 mice in each group). The serum level of IgE, IgG1 and IgG2a in orbital blood was determined by ELISA（n=5 mice in each group）.

Results: HE staining revealed increased BALF eosinophils and decreased pulmonary inflammation in group F compared with group B. The IFN-γ level in group F ［（298.75±26.09） pg/ml］ was significantly higher than those in groups B［（158.71±20.89） pg/ml］, C［（210.38±18.92） pg/ml］, D ［（229.44±13.00） pg/ml］ and E［（233.24±20.39） pg/ml］ （all P<0.01）. Similar results were also found for IL-10 and TGF-β, while the IL-13 levels in groups C ［（47.35±4.71） pg/ml］, D ［（41.90±4.28） pg/ml］, E［（41.05±6.50） pg/ml］ and F［（18.53±5.67） pg/ml］ were all significantly lower than that in group B ［（66.68±6.63） pg/ml］（all P<0.01）. The number of BALF eosinophils in group B ［5.65±0.91］×105/ml］ was significantly higher than that in group A ［（0.45±0.39）×105/ml］ （P<0.01）, while the BALF eosinophils in groups C ［（4.00±0.59）×105/ml］, D ［（3.39±0.63）×105/ml］, E ［（3.24±0.69）×105/ml］ and F ［（1.42±0.49）×105/ml］ decreased after immune treatment (all P<0.01). ELISA results showed that the serum IgE level in group F ［（5.26±1.72） ng/ml］ was significantly lower than those in group B ［（32.81±2.98） ng/ml］ and the other 3 treatment groups [group C, （20.06±3.17） ng/ml; D, （17.06±3.18） ng/ml; E, （16.23±3.61） ng/ml］. Similar results were also obtained for IgG1. In contrast, the serum IgG2a level in group F［（43.10±1.34） ng/ml］ was significantly higher than those in group B［（12.61±1.87） ng/ml］ and the other 3 treatment groups ［group C, （23.37±2.67） ng/ml; D, （25.60±2.10） ng/ml; E, （25.91±1.33） ng/ml］ （all P<0.01）.

Conclusion: Immunotherapy with chimeric TAT-IhC-DPTCE can effectively ameliorate the allergic airway response and pulmonary inflammation in mice.