Modulation of the Humoral Response to <i>Dermatophagoides pteronyssinus </i>Allergens in BALB/c Mice by Extract Modification and Adjuvant Use

Abstract

Background: Currently, several strategies are being used in order to improve the safety and efficacy of allergen-specific immunotherapy; these strategies include the use of modified hypoallergenic extracts as well as different adjuvants with immunomodulatory properties in combination with native or modified extracts. The objectives of this study were to investigate the humoral response generated in mice to modified Dermatophagoides pteronyssinus extracts in the presence or absence of two different adjuvants. Methods: BALB/c mice were inoculated either with native, depigmented or depigmented-polymerised D. pteronyssinus without adjuvants or combined with aluminium hydroxide or oligodeoxinucleotides containing CpG motifs. IgE concentration, specific total IgG, IgG1 and IgG2a titres were measured in mice sera and cross-reactivity inhibition experiments were performed. IgG antigenic profiles were obtained by immunoblotting for all formulations. Results: Inoculation of depigmented-polymerised extract induced statistically significant lower IgE levels than the native extract even when adsorbed onto aluminium hydroxide. When this extract was inoculated in the presence of oligodeoxinucleotides containing CpG motifs, it elicited high IgG levels, a high IgG2a/lgG1 ratio and low IgE production. Furthermore, the antigenic profiles observed after extract inoculation showed punctual differences between the depigmented-polymerised extract and the native or depigmented extracts. Conclusions: Our results suggest that the depigmentation and polymerisation process modifies the native extract’s antigenic and immunogenic properties and converts the depigmented-polymerised extract into a better choice for allergen-specific immunotherapy.

Depigmented Allergoids Reveal New Epitopes with Capacity to Induce IgG Blocking Antibodies

“…However, allergoids and Dpg-Pol molecules have different structure, size, and characteristics [14], and how they are handled by antigen-presenting cells is unknown yet. We have previously shown reduced activation of effector T cells by Dpg-Pol extracts compared to native allergen extracts but conserved activity of regulatory T cells [20]. Here we confirm that Dpg-Pol extracts induce IgG antibody response in vivo , broadly similar to that for native allergen extract.…”

“…However, the polymerization with glutaraldehyde may also modify the tertiary and quaternary structure of the molecules as we also observed recognition of specific IgG antibodies to new regions or epitopes in the individual allergens. Besides, the polymerization reaction modifies conformational epitopes that represent the majority of allergen IgE epitopes [5], and as has been previously demonstrated, Dpg-Pol extracts have greatly reduced IgE binding capacity in vivo and in vitro [20, 21] compared to native extracts. Depigmentation-polymerization process synthesized new antigens consisting of allergen chains with new epitopes, which have the capacity to stimulate the induction of specific IgG not present after immunization with native molecules, blocking new regions that native extracts are not able to block.…”

Inhibitory/Suppressive Oligodeoxynucleotide Nanocapsules as Simple Oral Delivery Devices for Preventing Atopic Dermatitis in Mice

“…1 Chemosynthetic immunofunctional oligodeoxynucleotides (ODNs) such as cytosine nonmethylated CpG-ODNs are also useful as adjuvants for vaccines against infectious agents, cancer, allergies, and inflammatory disorders. [2][3][4][5] A synthetic phosphorothioate (PS)-modified CpG-ODN was used in an in vivo/in vitro study involving various disease models. 6 For medical purposes, ODNs have been administered in a variety of ways, including via intraperitoneal (i.p.…”