Controlled release of a model vaccine by nanoporous ceramic microneedle arrays.

Current vaccination technology can advance from the use of novel ceramic nanoporous microneedle arrays (npMNA), where the material serves as a storage reservoir for vaccines. Moreover, npMNA will enhance vaccine efficacy by more precisely reaching skin dendritic cells, the kickstarters of T and B cell immunity. In the present study we assessed the efficacy of vaccination using npMNAs by in vivo application of OVA257-264 peptides mixed with agonistic anti-CD40 antibodies as adjuvant. The induction of OVA-specific CD8(+) T cells via npMNA was comparable with the frequency induced via intradermal injection using needle-syringe. However, only when expanding the vaccination area by using two npMNAs the frequencies of induced IFN-γ-specific effector CD8(+) T cells were comparable with those induced via needle-syringe injection. Analysis of vaccine release from npMNA in a human ex vivo skin explant model revealed that OVA257-264 peptides were indeed delivered intradermal, and release also increased by prolonging the npMNA application time on the human skin. Together, our studies demonstrate the potential of npMNA for vaccine delivery in human skin and in vivo induction of CD8(+) effector T cell responses.

In situ Delivery of Antigen to DC-SIGN(+)CD14(+) Dermal Dendritic Cells Results in Enhanced CD8(+) T-Cell Responses.

CD14(+) dendritic cells (DCs) present in the dermis of human skin represent a large subset of dermal DCs (dDCs) that are considered macrophage-like cells with poor antigen (cross)-presenting capacity and limited migratory potential to the lymph nodes. CD14(+) dDC highly express DC-specific ICAM-3-grabbing non-integrin (DC-SIGN), a receptor containing potent endocytic capacity, facilitating intracellular routing of antigens to major histocompatibility complex I and II (MHC-I andII) loading compartments for the presentation to antigen-specific CD8(+) and CD4(+) T cells. Here we show using a human skin explant model that the in situ targeting of antigens to DC-SIGN using glycan-modified liposomes enhances the antigen-presenting capacity of CD14(+) dDCs. Intradermal vaccination of liposomes modified with the DC-SIGN-targeting glycan Lewis(X), containing melanoma antigens (MART-1 or Gp100), accumulated in CD14(+) dDCs and resulted in enhanced Gp100- or MART-1-specific CD8(+) T-cell responses. Simultaneous intradermal injection of the cytokines GM-CSF and IL-4 as adjuvant enhanced the migration of the skin DCs and increased the expression of DC-SIGN on the CD14(+) and CD1a(+) dDCs. These data demonstrate that human CD14(+) dDCs exhibit potent cross-presenting capacity when targeted in situ through DC-SIGN.

Specificity of DC-SIGN for mannose- and fucose-containing glycans.

The dendritic cell specific C-type lectin dendritic cell specific ICAM-3 grabbing non-integrin (DC-SIGN) binds to "self" glycan ligands found on human cells and to "foreign" glycans of bacterial or parasitic pathogens. Here, we investigated the binding properties of DC-SIGN to a large array of potential ligands in a glycan array format. Our data indicate that DC-SIGN binds with K(d)<2muM to a neoglycoconjugate in which Galbeta1-4(Fucalpha1-3)GlcNAc (Le(x)) trisaccharides are expressed multivalently. A lower selective binding was observed to oligomannose-type N-glycans, diantennary N-glycans expressing Le(x) and GalNAcbeta1-4(Fucalpha1-3)GlcNAc (LacdiNAc-fucose), whereas no binding was observed to N-glycans expressing core-fucose linked either alpha1-6 or alpha1-3 to the Asn-linked GlcNAc of N-glycans. These results demonstrate that DC-SIGN is selective in its recognition of specific types of fucosylated glycans and subsets of oligomannose- and complex-type N-glycans.

Evaluation of the role of the endocytic receptor L-SIGN for cytoadhesion of Plasmodium falciparum-infected erythrocytes.

Hepatic cell populations play an important role during the malaria life cycle. L-SIGN, a homologue of DC-SIGN, mediating leukocyte and pathogen binding, is selectively expressed on liver endothelial cells. Here, we present evidence that L-SIGN acts as an endocytic cell surface receptor. However, P. falciparum-infected erythrocytes did not cytoadhere to L-SIGN. Thus, L-SIGN contributes to elimination of mannosylated ligands but does not participate in hepatic clearance of P. falciparum-infected erythrocytes.