Promoting Antigen Escape from Dendritic Cell Endosomes Potentiates Anti-Tumoral Immunity
57 Pages Posted: 21 Jun 2021 Publication Status: Published
More...Abstract
Background: Dendritic cells (DCs) are usually very efficient at activating CD8 T cells. However, their capacity to cross-present soluble antigens can be limited by non-specific degradation of captured antigens during endosome maturation, which would lead to the destruction of immunogenic epitopes. To bypass this limitation, we tested a new antigen formulation using AccumTM, a technology originally designed to enhance accumulation of antibody-drug conjugate in target cells by promoting endosome-to-cytosol escape.
Methods: Following chemical linking and characterization of the Accum-antigen complex, a series of in vitro antigen presentation assays were conducted to assess the T-cell activation potency of the antigen formulation. The generated cellular product was then tested in vivo for its capacity to elicit anti-tumoral responses in both prophylactic and therapeutic vaccination settings. Finally, allogeneic DCs pulsed with tumor lysate linked to AccumTM were characterized for their therapeutic potency.
Results: Linking the Accum moiety to the experimental xenoantigen ovalbumin caused endosomal damages resulting in enhanced intracellular protein processing by primary DCs. As a result, production of pro-inflammatory cytokines and chemokines was enhanced by responding T cells. When evaluated for their anti-tumoral properties, Accum-ovalbumin-pulsed DCs elicited potent effector and central memory CD8 T cells, which explains the complete and long-lasting protection observed in vaccinated mice despite multiple EG.7 T-cell lymphoma challenges. When combined with the anti-PD-1 immune checkpoint inhibitor, therapeutic vaccination using both syngeneic and allogeneic DCs pulsed with Accum-linked ovalbumin triggered potent anti-tumoral responses; an observation further enhanced using Accum-linked lymphoma tumor lysate proteins.
Conclusion: These highly favorable therapeutic effects highlight the promising potential of AccumTM as a distinct and potent technology platform suitable for the design of next generation cell cancer vaccines.
Keywords: Dendritic cells; Endosomes; AccumTM; Antigen Cross-Presentation; Anti tumoral Immunity; Immune Checkpoint Inhibitors
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