Immunostimulatory oligodeoxynucleotide from Bifidobacterium longum suppresses Th2 immune responses in a murine model

We have reported previously that novel immunostimulatory sequence (ISS) oligodeoxynucleotide (ODN) BL07S from a probiotic strain of Bifidobacterium longum inhibited immunoglobulin (Ig) E production in vitro. However, whether ISS-ODNs from probiotics regulate T helper type 2 (Th2)-polarized immune reactions in vivo remains unclear. To evaluate the inhibitory effects of ODN BL07S on type I allergic response, BALB/c mice were injected with or without ODN BL07S in the presence of ovalbumin (OVA) on days 0 and 14. Serum Ig levels (IgE, IgG1 and IgG2a) and cytokine levels (interferon (IFN)-γ, interleukin (IL)-12, IL-4, IL-5, IL-10 and IL-13) were investigated in splenocyte cultures from days 14-28. Production of OVA-specific and total IgE were significantly suppressed by administration of ODN BL07S, but not by ODN BL06S, a non-ISS-ODN. Compared to controls, ODN BL07S induced significantly lower levels of Th2 cytokines (IL-4 and IL-5) in splenocyte cultures, and significantly higher levels of serum OVA-specific IgG2a. These effects of ODN BL07S on modulation of Th2 immune response were dose-dependent. The present results demonstrate that ODN BL07S from genomic DNA of B. longum BB536 prevents antigen-induced Th2 immune responses in vivo, suggesting that ISS-ODNs from probiotics might be useful in preventing allergic disease.