Intradermal immunization with ovalbumin-loaded poly-epsilon-caprolactone microparticles conferred protection in ovalbumin-sensitized allergic mice.

Abstract

Background Despite immunotherapy has been reported as the only treatment able to revert the Th2 response, its administration has some disadvantages such as the requirement of multiple doses, possible side effects provoked by conventional adjuvants and the risk of suffering an anaphylactic shock. For that reasons, drug delivery systems appear to be a promising strategy due to its ability to i) transport the allergens, ii) protect them from degradation, iii) decrease the number of administrations and iv) act as immuno-adjuvants. Objective The aim of this work was to evaluate the properties of poly- -caprolactone (PCL) microparticles as adjuvants in immunotherapy using ovalbumin (OVA) as allergen model. For this purpose, the protection capacity of these microparticles (OVA PCL) against OVA allergy was studied in a murine model. Methods The humoral and cellular induced immune response generated by OVA encapsulated into PCL microparticles was studied immunizing BALB/c mice intradermically. Beside, OVAsensitized mice were treated with OVA PCL and OVA adsorbed to aluminium hydroxide (OVAAlum). Fifteen days after therapy, animals were challenged with OVA and different signs of anaphylactic shock were evaluated. Results One single shot by intradermal route with OVA PCL resulted in a Th2-type immune response. In OVA-sensitized mice, treatment with OVA PCL treatment elicited high OVA specific IgG but low levels of IgE. Furthermore, OVA PCL mice group displayed lower levels of serum histamine and higher survival rate in comparison with the positive control group. Conclusion The anaphylactic shock suffered by OVA PCL treated mice was weaker than the one induced in the OVA-Alum group. Hence, the intradermal immunization with OVA PCL microparticles induced hyposensitization in OVA-allergic mice.