[Immunotherapy effect of ploypeptide vaccine of allergen group 1 from Dermatophagoides farinae on asthma mice].

Objective: To investigate the enzymatic hydrolysates of ProDer f land their hydrolytic products for specific immunotherapy.

Methods: The asthma models of mice made by ProDer f 1 allergen were treated by using two kinds of hydrolysates as vaccine for analyzing their effects of immunotherapy. Fifty female BALB/c mice were randomly divided into 5 groups (n = 10 for each), i.e., a PBS group, an asthma group, an immunotherapy group by ProDer f 1 protein, an immunotherapy groups by papain hydrolysates and trypsin hydrolysates. On day 0, 7 and 14, the mice were intraperitoneally injected with 10 µg of ProDer f 1 allergen, which was dissolved in 100 µl PBS containing 2% (W/V) Al (OH)3 suspension. At day 21, the animals were caged in the airway challenge apparatus, and challenged by nebulized inhalation of allergen suspension (0.5 µg/ml) for 30 min for 7 successive days. The mice were undergone allergen specific immunotherapy (ASIT) by intraperitoneal injection and of the immunotherapy group by ProDer f 1 protein, immunotherapy groups by papain hydrolysates and trypsin hydrolysates (100 µg/ml) in a dose of 200 µl of reactive allergens, 30 min prior to the inhalation treatment at day 25, 26 and 27, respectively. The PBS group was managed with both intraperitoneal injection and aerosol of PBS. Twenty-four hours after the last challenge, all the mice were sacrificed. The bronchoalveolar lavage fluid (BALF) and sera were collected, and the splenocytes were cultured. The levels of IL-4, IL-10, IL-17 and IFN-γ in BALF and supernatant of splenocytes cultured (SSCC) were detected by ELISA, and the serum levels of specific IgE and IgG2a antibodies were also detected by ELISA.

Results: Compared with the asthma group, the histo- logic examination of the lungs taken from the mice in the immunotherapy group by ProDer f 1 protein, immunotherapy groups by papain hydrolysates and trypsin hydrolysates showed alleviated peribronchial and perivascular inflammatory infiltration, absently of eosinophils. The normal lung architectures were also exhibited, particularly, the epithelium was of normal size and morphology, similar to that of the PBS-challenged group. The levels of IL-4 in BLAF of the ASIT groups and asthma group were (231.61 ± 11.73), (206.20 ± 14.33), (200.44 ± 9.34), (299.68 ± 12.46) pg/ml; the levels of IL-10 in BLAF were (361.87 ± 13.62), (376.27 ± 20.57), (413.57 ± 12.98), (171.28 ± 19.79) pg/ml; the levels of IL-17 in BLAF were (142.12 ± 5.01), (128.27 ± 5.34), (130.79 ± 6.30), (273.59 ± 11.56) pg/ml; the levels of IFN-γ in BLAF were (229.60 ± 11.32), (269.13 ± 11.98), (282.25 ± 19.65), (147.76 ± 11.36) pg/ml. The levels of IL-4 in SCCS of the ASIT groups and asthma group were (218.54 ± 12.62), (220.21 ± 10.73), (201.59 ± 18.54), (256.86 ± 15.53) pg/ml; the levels of IL-10 were (360.45 ± 13.10), (383.41 ± 19.81), (413.51±13.14), (173.50 ± 20.25) pg/ml; the levels of IL-17 were (154.23 ± 5.18), (137.72 ± 6.66), (141.01 ± 7.35), (297.55 ± 8.97) pg/ml, the levels of IFN-γ were (243.22 ± 25.01), (275.20 ± 14.65), (284.67 ± 25.87), (154.54 ± 17.45) pg/ml. The levels of antigen-specific IgE antibody of the ASIT groups and asthma group were (309.66 ± 13.56), (256.61 ± 40.64), (248.83 ± 10.51), (359.60 ± 29.48) µg/ml, and the antigen-specific IgG2a antibody levels were (8.87 ± 0.82), (9.15 ± 0.83), (10.56 ± 1.68), (7.04 ± 0.42) µg/ml. The resulting serum antigen-specific IgE antibody levels suggested that the IgE levels in the immunotherapy group by ProDer f 1 protein, immunotherapy groups by papain hydrolysates and trypsin hydrolysates were significantly lower than that in the asthma group. Conversely, the level of antigen-specific IgG2a in sera was significantly higher in the immunotherapy group by ProDer f 1 protein, immunotherapy groups by papain hydrolysates and trypsin hydrolysates than that in the asthmatic group. The levels of IL-4, IL- 17 in BALF and SCCS in the immunotherapy group by ProDer f 1 protein, immunotherapy groups by papain hydrolysates and trypsin hydrolysates significantly decreased, compared with that in the asthma group. However, the levels of IL-10 and IFN-γ in BALF and SCCS in the immunotherapy group by ProDer f 1 protein, immunotherapy groups by papain hydrolysates and trypsin hydrolysates were increased dramatically in the immunotherapy group by ProDer f 1 protein, immunotherapy groups by papain hydrolysates and trypsin hydrolysates than that in the asthma group.

Conclusion: The hydrolytic products above-mentioned can alleviate asthmatic symptoms effectively after the antigen-specific immunotherapy in murine asthma models.