Vaccination with the recombinant allergen ProDer p 1 complexed with the cationic lipid DiC14-amidine prevents allergic responses to house dust mite.

The present study evaluated the prophylactic potential of ProDer p 1, the recombinant precursor form of the major mite allergen Der p 1, combined with the cationic lipid diC14-amidine in a murine model of house dust mite allergy. Naive mice vaccinated with the amidine/allergen complex developed a Th1-biased immune response characterized by the absence of specific IgE, the production of specific IgG2a, and the presence of IFN-gamma in splenocyte cultures. In contrast, ProDer p 1 adjuvanted with alum induced typical strictly Th2-biased allergic responses with strong IgG1 and IgE titers and IL-5 secretion. Removal of negatively charged sialic acids in ProDer p 1 or increasing the ionic strength reduced the binding of ProDer p 1 to the cationic liposomes and resulted in a decrease of the allergen immunogenicity, suggesting that complexation is required for triggering an optimal immune response. Finally, prophylactic vaccination with ProDer p 1-diC14-amidine reduced drastically the production of specific IgE and airway eosinophilia following subsequent immunization with Der p 1-alum and challenge with aerosolized house dust mite extracts. In conclusion, recombinant ProDer p 1 complexed with diC14-amidine could represent an efficient prophylactic vaccine against house dust mite allergy.

Heat denaturation affects the ProDer p 1 IgE reactivity and downregulates the development of the specific allergic response.

BACKGROUND: Modified allergens with reduced IgE-binding activity represent an elegant approach to circumvent the risk of anaphylactic reactions in allergen-specific immunotherapy. OBJECTIVE: The current work investigated the effect of heat denaturation on the allergenic properties of recombinant ProDer p 1, a precursor form of the major house dust mite allergen Der p 1. METHODS: The IgE reactivity was estimated by direct and competition ELISA. The immunogenicity of heat-denatured ProDer p 1 was evaluated in naive and Der p 1-allergic mice. RESULTS: Heat denaturation in reducing conditions drastically reduced the in vitro ProDer p 1 IgE reactivity toward human allergic sera. In naive mice, heat-denatured ProDer p 1 generated mixed T(H)1-T(H)2 responses characterized by the absence of specific IgE with concomitant rise in specific IgG2a titers and the presence of IL-5 and IFN-gamma in splenocyte cultures. In contrast, natural Der p 1 or native ProDer p 1 induced typical strict T(H)2-biased allergic responses with strong IgG1 and IgE titers, whereas spleen cells exhibited only high IL-5 secretion. Moreover, native or heat-denatured ProDer p 1 vaccinations prevented airway eosinophil infiltrations after challenge. Although native or heat-treated ProDer p 1 adjuvanted with SBAS1b induced mixed T(H)1-T(H)2 responses in allergic mice, heat-denatured ProDer p 1, compared with native ProDer p 1, proved to be more effective in redirecting the T(H)2-allergic response toward T(H)1. CONCLUSION: Taken together, our results suggest that variants of Der p 1 with reduced IgE-binding reactivity could represent hypoallergenic molecules suitable for allergen-specific immunotherapy.