Programming Immunity with Nanoscale Architecture

Introduction:: Vaccines activate the immune system through delivery of an adjuvant and antigen. However, previous efforts have focused on vaccine composition with less consideration for how components are arranged and presented to an immune cell.¹ To raise a potent immune response against highly mutative aggressive tumors, vaccines must activate multi-faceted immunity.² However, vaccine design considerations targeting multiple immune cell types are underexplored. We illustrate how vaccine antigen placement impacts the propagation of immunity. We explore the design space guiding nanoscale antigen placement and how it changes immune cells at the transcripteomic, protein, cellular, and organismal levels.

Materials and Methods:: Oligonucleotide structures were synthesized using solid-phase standard phosphoramidite synthesis. Cholesterol anchors were used for oligonucleotide insertion into DOPC liposomes. Peptides (antigens) were chemically conjugated to DNA through disulfide linkages, or encapsulated into liposome cores. Immunological readouts (cytokine production, surface marker expression, memory phenotype) was analyzed in vivo and ex vivo via flow cytometry. Tumor growth and animal survival was measured across multiple models (lymphoma, colon, melanoma) using C57BL/6 mice.

Results, Conclusions, and Discussions:: We designed a library of vaccine structures with the ability to specifically position multiple antigens at the nanoscale to activate either CD8⁺ or CD4⁺ T cells³. We observed that nanoscale arrangement of antigen altered its processing in dendritic cells (DCs), with specific architectures optimizing MHC-I versus MHC-II presentation pathways. The structural placement of antigen influenced gene expression in DCs and in activated CD8⁺ and CD4⁺ T cells, as measured through RNA sequencing, with one structure upregulating inflammatory responses and chemotaxis pathways. Holistically, the arrangement of antigens in the nanostructure manipulated the interaction between immune cells and the tumor microenvironment, and enhanced the circulation and cytotoxic ability of antigen-specific immune cells. In three tested tumor models (lymphoma, colon, and melanoma), the ability to raise antigen-specific circulating T cells amongst PBMCs was significantly elevated for the architecture that optimized MHC-I versus MHC-II presentation pathways. This architecture positioned MHC-II antigen internally and MHC-I antigen externally. The observed immunological findings correlated with structurally-defined tumor growth curves across these multiple mouse models. The antigen-optimizing nanostructure consistently elongated animal survival and synergized effectively with anti-PD-1 checkpoint inhibitor therapy.

Overall, the ability to define antigen placement within vaccine architecture uncovered key structure-function relationships defining antigen processing and immune propagation. This work highlights how vaccines can be developed to raise complex multi-faceted immunity through manipulation of antigen architecture in a construct. Moreover, this works provides a path forward towards harnessing vaccine design to raise unique T cell profiles and defined immune responses.


Acknowledgements (Optional): : Affiliations: ¹Department of Biomedical Engineering, Boston University; ²Department of Chemistry and International Institute for Nanotechnology, Northwestern University

References (Optional): : 1.Wang, et al. Proc Natl Acad Sci 2019, 10473. 2.Beatty, et al. Clin Cancer Res 2015, 687. 3.Teplensky, et al. Nat Biomed Eng 2023, 1-17.