Glycan-modified liposomes boost CD4+ and CD8+ T-cell responses by targeting DC-SIGN on dendritic cells

Cancer immunotherapy requires potent tumor-specific CD8+ and CD4+ T-cell responses, initiated by dendritic cells (DCs). Tumor antigens can be specifically targeted to DCs in vivo by exploiting their expression of C-type lectin receptors (CLR), which bind carbohydrate structures on antigens, resulting in internalization and antigen presentation to T-cells. We explored the potential of glycan-modified liposomes to target antigens to DCs to boost murine and human T-cell responses. Since DC-SIGN is a CLR expressed on DCs, liposomes were modified with DC-SIGN-binding glycans Lewis (Le)B or LeX.

Glycan modification of liposomes resulted in increased binding and internalization by BMDCs expressing human DC-SIGN. In the presence of LPS, this led to 100-fold more efficient presentation of the encapsulated antigens to CD4+ and CD8+ T-cells compared to unmodified liposomes or soluble antigen. Similarly, incubation of human moDC with melanoma antigen MART-1-encapsulated liposomes coated with LeX in the presence of LPS led to enhanced antigen-presentation to MART-1-specific CD8+ T-cell clones. Moreover, this formulation drove primary CD8+ T-cells to differentiate into high numbers of tetramer-specific, IFN-γ-producing effector T-cells.

Together, our data demonstrate the potency of a glycoliposome-based vaccine targeting DC-SIGN for CD4+ and CD8+ effector T-cell activation. This approach may offer improved options for treatment of cancer patients and opens the way to in situ DC-targeted vaccination.