Co-Delivery of Ovalbumin and CpG Motifs into Microparticles Protected Sensitized Mice from Anaphylaxis

Abstract

Background: Two major drawbacks of current subcutaneous specific immunotherapy are the risk to induce severe anaphylactic reactions and the need of multiple injections of the allergen to reduce IgE-mediated hypersensitivity. The sustained release of allergens over time provided by poly(lactide-co-glycolide) microparticles (MP) could mimic the current therapeutic schedule and decrease their allergenicity. Moreover, MP could also co-deliver Th1 immunoadjuvants, such as CpG motifs. Methods: Ovalbumin (OVA)-sensitized BALB/c mice were treated intradermally with OVA or OVA plus CpG containing MP. OVA-specific IgG1 and IgG2a as well as IgE total levels and cytokine production were assessed throughout the experiment. The protection exerted by the MP against allergen challenge was estimated with body temperature changes, mortality and other symptoms. Results: Microparticulated treatments, irrespective of the presence of CpG motifs, elicited a lower IgE/IgG2a ratio than those induced by the allergen in solution (free or with adjuvants). However, after induction of the anaphylactic shock, only mice treated with MP co-encapsulating OVA plus CpG showed a significant lower decrease in body temperature and were totally protected from death. Mice that were injected with OVA plus CpG in solution or with Alum displayed a marked fall of temperature accompanied by high mortality rates (70–100%). Conclusion: MP encapsulating both OVA, as an allergen model, and CpG sequences, as a pro-Th1 adjuvant, decreased the risk for OVA sensitization (IgE induction) and protected sensitized mice from anaphylactic shock after allergen provocation. Therefore, the combination of allergens and CpG sequences into MP could perform a safer alternative to current specific immunotherapy.

Emerging therapies for food allergy

“…Further, linking CpG with allergen has reduced anaphylactic reactions to allergen when used either as a preventative therapy or as treatment in the form of s.c. injection or e.c. immunotherapy (114)(115)(116)(117)(118) in murine models. In humans, a similar TLR9 agonist, phosphorothioate oligodeoxyribonucleotide DNA, was coupled to ragweed antigen and showed some efficacy in a pilot s.c. injection study (119).…”

Carbohydrate modified ultrafine ceramic nanoparticles for allergen immunotherapy

“…In case of aquasomes, antigens are presented partly by the B cell through the MHC II pathway leading to a good antibody response, while part of the antigen is cleaved within the antigen presenting cells and presented through MHC class I pathway, leading to a Th1/CTL response [13,14,16,18]. As it is well known, immunotherapy in humans should be based on the decrease of a Th2 response by enhancing the Th1 response, and this balance is achieved by increasing the activity of the Treg lymphocytes [7]. Treg cytokines (IL-10, TNF-α) play a key role in preventing IgE and Th2 expansion [22,23].…”

“…Despite the efficacy of SIT, there are concerns with the treatment including difficulties in standardization of allergen extracts, patient compliance due to frequent injections, long treatment duration and safety issues comprising local side-effects and risk of anaphylaxis [1,7]. One of the strategies to improve vaccines for SIT is to use adjuvants that can modulate the allergen-specific T cell response.…”

Nanoparticle Based-immunotherapy Against Allergy

“…These NP formulations induced innate immune responses mediated by a TLR-2 and TLR-4 dependent manner and maduration of DC with a significant up-regulation of CD40, CD80, and CD86 and a biased Th1 present response in animal models [73,74]. This is an important finding since it has been recently shown that the use of multiple TLR-agonists carried by nanoparticles influence the induction of long-term memory cells, being the ultimate goal for any vaccine the stimulation of long-lasting protective immunological memory [75][76][77][78].…”