Edge Length-Programmed Single-Stranded RNA Origami for Predictive Innate Immune Activation and Therapy

Ligands targeting nucleic acid-sensing receptors activate theinnate immune system and play a critical role in antiviral and antitumoraltherapy. However, ligand design for in situ stability,targeted delivery, and predictive immunogenicity is largely hamperedby the sophisticated mechanism of the nucleic acid-sensing process.Here, we utilize single-stranded RNA (ssRNA) origami with precisestructural designability as nucleic acid sensor-based ligands to achieveimproved biostability, organelle-level targeting, and predictive immunogenicity.The natural ssRNAs self-fold into compact nanoparticles with definedshapes and morphologies and exhibit resistance against RNase digestion in vitro and prolonged retention in macrophage endolysosomes.We find that programming the edge length of ssRNA origami can preciselyregulate the degree of macrophage activation via atoll-like receptor-dependent pathway. Further, we demonstrate thatthe ssRNA origami-based ligand elicits an anti-tumoral immune responseof macrophages and neutrophils in the tumor microenvironment and retardstumor growth in the mouse pancreatic tumor model. Our ssRNA origamistrategy utilizes structured RNA ligands to achieve predictive immuneactivation, providing a new solution for nucleic acid sensor-basedligand design and biomedical applications.