Abstract
Multivalent presentation of ligands often enhances receptor activation and downstream signaling. DNA origami offers precise nanoscale spacing of ligands, a potentially useful feature for therapeutic nanoparticles. Here we introduce a “square block” DNA origami platform to explore the importance of spacing of CpG oligonucleotides, which engage Toll-like receptors and thereby act as danger signals for dendritic cells. Through in vitro cell-culture studies and in vivo tumor-treatment models, we demonstrate that square blocks induce Th1 immune polarization when CpG is spaced at 3.5 nm. We observe that this DNA origami vaccine enhances DC activation, antigen cross-presentation, CD8 T cell activation, Th1-polarized CD4 activation and NK cell activation. The vaccine also synergizes effectively with anti-PD-L1 for improved cancer immunotherapy in melanoma and lymphoma models and induces long-term T cell memory. Our results suggest that DNA origami may serve as an advanced vaccine platform for controlling adjuvant spacing and co-delivering antigens.
One Sentence Summary This study developed a DNA origami-based cancer vaccine (DoriVac) that co-delivers antigen and CpG immune adjuvant with an optimal spacing for Th1 immune polarization.
Competing Interest Statement
W.M.S, J.H.R. and Y.C.Z. are inventors on U.S. patent application PCT/US2020/036281 held by Dana-Farber Cancer Institute, Korea Institute of Science & Technology, and Wyss Institute (filed on 6/5/2020) partially based on this work. All other authors declare that they have no competing interests.
Footnotes
In this revised manuscript, we have performed the following experiments over the last year, specifically: 1.We have included confocal images colocalizing the DNA origami vaccine and endosomes 2.We have validated the spacing effects on human pDCs, human moDCs and mouse RAW264.7 cells. 3.We have compared DoriVac with liposomes carrying the same amount of antigen and adjuvant. DoriVac showed 12 times more SIINFEKL MHC I expression on the RAW264.7 cells. 4.We have investigated more signaling pathways and identified that TLR13 might also become involved in DC activation in mouse BMDCs. 5.We have evaluated the vaccine distribution to the draining LN and clearance by liver and kidney. 6.We have investigated neoantigen conjugated vaccine in B16F10 mouse model and identified that NK cells were also highly activated in DoriVac applied groups. 7.We have profiled cytokines in the blood after three doses of vaccination and observed significant increases of type 1 cytokines. 8.We also have tested the vaccine efficacy in a lymphoma model and validated the durable CD8 and CD4 T cell responses.
