Intranasal therapy with CpG DNA alone for the control of allergic rhinitis

Many people all over the world suffer from allergic rhinitis, induced by Th2 responses. CpG DNA, containing a central unmethylated C-G dinucleotide, promotes Th1 responses. Consequently, Th2 responses decrease. Systemic administration of CpG DNA could attenuate allergic rhinitis. However, studies investigating the effects of intranasal therapy with CpG DNA alone on allergic rhinitis are rare. Therefore, we estimated the effectiveness of intranasal administration of CpG DNA alone on allergic rhinitis compared with intradermal administration. Mice were sensitized intraperitoneally and challenged intranasally with Cryptomeria japonica. Therapy with CpG DNA alone was performed during the challenge, either intranasally or intradermally. Immunologic variables and nasal symptoms were examined. Intranasal administration of CpG DNA alone significantly reduced nasal symptoms, nasal eosinophilia, and the levels of IgE as well as IL-5 production from nasal lymphocytes and splenocytes, although intradermal administration of CpG DNA alone did not show a significant reduction. This study demonstrated that CpG DNA has effects not only on splenocytes but also on nasal lymphocytes, and that the intranasal administration of CpG DNA alone is useful in the management of allergic rhinitis.