Kevin R. Trabbic1, Kristopher A. Kleski1, and Joseph J. Barchi Jr1
- Chemical Biology Laboratory, Center for Cancer Research, National Cancer Institute at Frederick, Frederick, Maryland 21702, United States
We have developed a novel antigen delivery system based on polysaccharide-coated gold nanoparticles (AuNPs) targeted to antigen-presenting cells (APCs) expressing Dectin-1. AuNPs were synthesized de novo using yeast-derived β-1,3-glucans (B13G) as the reductant and passivating agent in a microwave-catalyzed procedure, yielding highly uniform and serum-stable particles. These were further functionalized with both a peptide and a specific glycosylated form from the tandem repeat sequence of mucin 4 (MUC4), a glycoprotein overexpressed in pancreatic tumors. The glycosylated sequence contained the Thomsen–Friedenreich disaccharide, a pan-carcinoma, tumor-associated carbohydrate antigen (TACA), which has been a traditional target for antitumor vaccine design. These motifs were prepared with a cathepsin B protease cleavage site (Gly-Phe-Leu-Gly), loaded on the B13G-coated particles, and these constructs were examined for Dectin-1 binding, APC processing, and presentation in a model in vitro system and for immune responses in mice. We showed that these particles elicit strong in vivo immune responses through the production of both high-titer antibodies and priming of antigen-recognizing T-cells. Further examination showed that a favorable antitumor balance of expressed cytokines was generated, with limited expression of immunosuppressive Il-10. This system is modular in that any range of antigens can be conjugated to our particles and efficiently delivered to APCs expressing Dectin-1.