Allergen-specific immunotherapy with monomeric allergoid from house dust mites dermato-phagoides pteronyssinus in a mouse allergic rhinitis model

Abstract

Background. The aim of this study was to investigate the efficacy of the allergen-specific immunotherapy (ASIT) with monomeric allergoid (sD1) obtained by succinylation of the allergenic extract from house dust mite Dermatophagoides pteronyssinus (D. pteronyssinus) (D1) in experimental mouse allergic rhinitis model (MARM). Materials and methods. BALB/c mice were immunized with non-modified extract D1 from house dust mite D. pteronyssinus (Der p) in mixture with aluminum hydroxide [Al(OH)3] three times in a three week intervals and then in 6 weeks after the last immunization were challenged with allergenic extract D1 by intranasal administration. Experimental ASIT was performed during the interval between the last immunization and the beginning of challenge. The first group of animals was treated with «sham ASIT» receiving of 16 subcutaneous (s.c.) injections of phosphate-buffered saline (PBS); the second group received 16 s.c. injections of non-modified D1 in increasing doses (in protein equivalent): 1; 10; 100 and 1000 pg/mouse; the third group received 8 s.c. injections ofsDl in increasing doses (in protein equivalent): 100; 550 and 1000 pg/mouse; the fourth group received combined ASIT consisted of 4 s.c. injections of sD1 in doses (in protein equivalent): 100; 550; 1000 pg/mouse and 4 sublingual (s.l.) administrations of sD1 in a dose of 1000 pg/mouse. The fifth group served as a negative control and received sham immunization, ASIT and challenge with PBS. Immediately after the last challenge and 24 hours later the clinical signs of MARM: sneezings (counts per minute) and breath frequency (assessed by non-invasive plethysmography) were evaluated. 48 hours after the last challenge animals of all groups were sacrificed and necessary material (whole head) was collected for histological assessment of the severity of allergic rhinitis in the nasal cavity. To obtain sera samples blood was collected from all groups of animals three times: 7 days after final immunization, 1 day before the challenge and 24 hours after the last challenge. Levels of anti-Der p IgE, IgG1, IgG2a in individual sera samples were determined by enzyme-linked immunosorbent assay (ELISA). Results. It is shown that all three variants of ASIT (groups 2, 3, 4) significantly reduced the number of sneezing acts. The greatest decrease was seen in the group 3 which was treated s.c with monomeric allergoid sD1. The number of respiratory acts per minute in the animals of groups 2 and 4 treated with non-modified D1 and monomeric allergoid sD1 (combined ASIT - s.c. and s.l. administration) respectively, were significantly higher than that of group 1 (MARM). The levels of anti-Der p IgE in groups 1, 2, 3 and 4 were increased after the 3rd immunization in comparison with group 5 (negative control). After ASIT the levels of anti-Der p IgE in groups 2, 3 and 4 were elevated in compare to group 5 (negative control) and group 1 (positive control - MARM). However, after the challenge the highest levels of anti-Der p IgE were observed in groups 1 and 4, while in group 3 we saw a moderate decrease of anti-Der p IgE and in the group 2 the levels of anti-Der p IgE were significantly lower than that of group 1 (MARM). The levels of anti-Der p IgG1 were significantly increased in groups 2, 3, 4 during and after ASIT as well as after challenge. The levels of anti-Der p IgG2a in groups 3 and 4 demonstrated a trend of increasing after ASIT. Anti-Der p IgG2a levels in group 4 after the challenge were significantly higher than that of group 1 (MARM). Histological evaluation has shown that overall inflammation, mucous exudation, hyperplasia of the mucosa in the nasal cavity were expressed significantly in groups 1 and 2 in comparison with group 5 (negative control). At the same time group 2 demonstrated a slight reduction of features designated above, and in groups 3 and 4 (ASIT with sD1 and combined s.c/s.l. ASIT, respectively) we observed a complete suppression of these inflammation parameters. Conclusion. These data indicate that ASIT with monomeric allergoid from house dust mite D. pteronyssinus obtained by succinylation may be a novel safe and effective approach for the treatment of allergic rhinitis including carrying out of combined course of injectable and sublingual therapy that may enhance the effect of treatment and patients’ quality of life.