OBJECTIVETo study the preparation of recombinant house dust mite group 1 allergen vaccine (chitosan-pVAX1-Derp1 nanoparticles, pVAX1-Derp1/CS) and to investigate the efficacy and mechanism of intranasally given chitosan-pVAX1-Derp1 nanoparticles on mouse model with allergic rhinitis (AR).

METHODSThe chitosan-pVAX1-Derp1 nanoparticles was prepared by complex coacervation, and its nature was identified and analysed. A total of 40 BALB/c rats were randomly divided into 5 groups: the normal group (group A), the AR model group (group B), the chitosan (CS) prevention group (group C), the pVAX1-Derp1 prevention group (group D), and the pVAX1-Derp1/CS prevention group (group E). The nasal cavity of rats in the group B, C, D and E were dripped with phosphate buffered saline (20 µl), CS (20 µl), pVAX1-Der p1 (20 µl), pVAX1-Derp1/CS nanoparticles (20 µl) on the first day and day 8, once daily. Rats in the latter 4 group were sensitized with Der p1 and Al(OH)3 in day 15 and day 22, and challenged with Der p1 to establish AR model from day 36 to day 43, while rats in group A were treated with PBS. Then the level of cytokines in serum was assayed by ELISA, inflammatory reactions in nasal mucosa were analyzed by haematoxylin and eosin staining.

RESULTSpVAX1-Derp1/CS nanoparticles was successfully constructed, the mean grain size of pVAX1-Derp1/CS was (205.3 ± 12.8) nm, and the zeta potential was (30.5 ± 5.6) mV. In nasal mucosa tissue, group B and C showed significant allergic inflammation, while group D and E showed lighter allergic inflammation. Compared with the group B, the group D and E could effectively reduced serum IgE level and IL-4 level [group B: (120.0 ± 8.8) ng/ml, (248.7 ± 10.6) pg/ml; group D: (109.6 ± 14.5) ng/ml, (192.5 ± 10.2) pg/ml; group E: (88.1 ± 8.3) ng/ml, (165.7 ± 9.7) pg/ml; IgE: t value were 3.5, 6.9, all P < 0.01; IL-4: t value were 10.0, 15.2, all P < 0.01], and increased IFN-γ level [group B: (709.0 ± 26.5) pg/ml; group D: (856.3 ± 37.4) pg/ml; group E: (904.8 ± 37.7) pg/ml; t value were 8.2, 10.8, all P < 0.01)]. IL-10 level of group D [(129.9 ± 16.1) pg/ml] and E [(107.1 ± 11.8) pg/ml] was lower than IL-10 level of group B [(160.6 ± 24.2) pg/ml]. The difference were significantly (t value were 2.9, 5.5, all P < 0.05).

CONCLUSIONSChitosan can effectively encapsulate pVAX1-Derp 1 and inhibit nuclease degradation of the plasmid, the DNA vaccine has some preventive effect on AR animal model by nasal immunization.