, 2008; Momoi et al., 2008; Liu et al., 2010). However, intragastrically administered antigens must be subjected to degradation processes prior to absorption through the lamina propria or Peyer’s patches. This requires that a mouse be challenged with a much greater amount of antigen than other routes, which may induce immune tolerance (Mestecky et al., 1996; McSorley & Garside, 1999). In contrast, nasal administration is a well-established route of mucosal immunization because antigens are not subjected to such degradation BVD-523 mw processes. However, nasally administered antigens, such as the cholera

toxin or influenza vaccine, threaten to migrate to the olfactory nerve and on to the central nervous system given their affinity for nerve tissue (van Ginkel et al., 2000; Mutsch et al., 2004). These drawbacks make sublingual vaccination a superior alternative given that a much lower dose is required than for intragastric vaccination. Sublingual mucosa are permeable to drugs and can deliver low-molecular-weight molecules to the bloodstream while avoiding enterohepatic RXDX-106 chemical structure circulation and the immediate destruction of ingested molecules by gastric acid or partial first-pass effects of hepatic metabolism (Cuburu et al., 2007). Moreover, sublingually administered antigens have no propensity to migrate

to the central nervous system (Cuburu et al., 2007). In addition to these advantages, sublingual vaccination induces substantially greater immune responses compared with nasal vaccination. Together, these advantages indicate that sublingual administration is an effective means of delivering drugs or low-molecular-weight molecules to protect

against infectious diseases. MBP has been used as a chaperone component in vaccines to enhance Ag-specific humoral and cellular Thalidomide immune responses (Seong et al., 1997; Rico et al., 1998). Therefore, we assessed the efficacy of sublingual immunization with the fusion protein 25k-hagA-MBP. Our results demonstrate that a sublingual challenge with 25k-hagA-MBP elicited high titers of the 25k-hagA-MBP-specific serum IgG and IgA Ab responses. Furthermore, these antibodies persisted for almost 1 year. As MBP adjuvanticity is mediated via signaling through TLR4 (Fernandez et al., 2007), we also tested whether the antigen-specific immune responses are induced in TLR-4 (the receptor of MBP) KO mice. As expected, neither antigen-specific IgG nor IgA antibodies were detected after sublingual immunization in these mice (S. Yuzawa, T. Kurita-Ochiai, T. Hashizume, R. Kobayashi, Y. Abiko & M. Yamamoto, unpublished data). A significantly high salivary IgA Ab titer was associated with the number of 25k-hagA-MBP-specific Ab-producing cells in the salivary gland. Our results also showed that predominant mononuclear cell proliferation and cytokine production occurred in SMLs, in which 25k-hagA-MBP-specific helper T cells produced significant IL-4 and IFN-γ, which favor Th1-type and Th2-type responses, together with the increased production of TGF-β.