Intradermal delivery of Cryj1 loaded in CpG DNA hydrogel for inhibiting allergic reactions in mice

Immunotherapy for allergic rhinitis alleviates symptoms associated with antigen exposure by administering pathogenic antigens. However, many current immunotherapies fail to induce sufficient immune responses, resulting in frequent and prolonged hospital visits. Consequently, the development of more effective immunotherapies is necessary. In this study, we focused on the skin, which is rich in immune cells, as an administration site for inducing antigen-specific immune responses. To efficiently and sustainably deliver the cedar pollen antigen Cryj1 to immune cells, we attempted to load Cryj1 in an immunostimulatory CpG DNA hydrogel, prepared using self-gelatinizable nucleic acid technology. In this technology, the hydrogel became gelatinized by self-assembly of multiple predesigned DNA units containing potent CpG motifs. Cryj1 loaded in the CpG DNA hydrogel showed sustained release, was taken up by mouse macrophage-like RAW264.7 and mouse dendritic DC2.4 cells, and induced efficient production of interleukin-12 after intradermal injection into mice. Intradermal injection of Cryj1 loaded CpG DNA hydrogel into mice increased the production of Cryj1-specific IgG while suppressing the production of immunoglobulin E (IgE) antibodies. Furthermore, when Cryj1 was resensitized to mice, a stronger induction of IgG production and suppression of IgE production was observed. These results suggest that intradermal administration of Cryj1 loaded CpG DNA hydrogel is a novel immunotherapy for allergic symptoms caused by cedar pollen and can be used as a replacement for current immunotherapies.