Suppression of dust mite allergy by mucosal delivery of a hypoallergenic derivative in a mouse model

Allergic asthma caused by house dust mite (HDM) is becoming a public health problem. Specific immunotherapy is considered to be the only curative treatment, but it is always associated with IgE-mediated side effects in the therapy process. A few studies showed that the disruption of allergen IgE epitopes could reduce IgE reactivity and thus reduce allergenic activity. In this study, a hypoallergenic derivative of the major HDM allergen Der p2 was constructed by genetic engineering. This derivative was confirmed to have a considerably reduced IgE reactivity compared with Der p2. For its application in vivo, recombinant Lactococcus lactis (LL-DM) was engineered to deliver the Der p2 derivative to the intestinal mucosal surface. Oral administration of LL-DM significantly alleviated Der p2-induced airway inflammation, as shown by reduced inflammatory infiltration and a reduction in Th2 cytokines in bronchoalveolar lavage. This protective effect was associated with an up-regulation of specific IgG2a and a decrease in IL-4 level in the spleen which may affect specific IgE response. Moreover, the levels of regulatory T cells in the mesenteric lymph nodes and spleen were markedly increased in mice fed with LL-DM, suggesting that LL-DM can inhibit allergic responses via the induction of regulatory T cell. Our results indicate that the Der p2 derivative is a promising therapeutic molecule for specific immunotherapy and recombinant lactic acid bacteria could be developed as a promising treatment or prevention strategy for allergic diseases.