Self-assembling DNA hydrogel-based delivery of immunoinhibitory nucleic acids to immune cells

Immunoinhibitory oligodeoxynucleotides (INH-ODNs) are promising inhibitors of Toll-like receptor 9 (TLR9) activation. To efficiently deliver INH-ODNs to TLR9-positive cells, we designed a Takumi-shaped DNA (Takumi) consisting of two partially complementary ODNs as the main component of a DNA hydrogel. Polyacrylamide gel electrophoresis showed that Takumi-containing INH-ODNs (iTakumi) and iTakumi-based DNA hydrogel (iTakumiGel) were successfully generated. Their activity was examined in murine macrophage-like RAW264.7 cells and DC2.4 dendritic cells by measuring tumor necrosis factor-α and interleukin-6 release after the addition of a TLR9 ligand (CpG ODN). Cytokine release was efficiently inhibited by the iTakumiGel. Flow cytometry analysis and confocal microscopy showed that cellular uptake of INH-ODN was greatly increased by the iTakumiGel. These results indicate that a Takumi-based DNA hydrogel is useful for the delivery of INH-ODNs to immune cells to inhibit TLR9-mediated hyperinduction of proinflammatory cytokines. From the Clinical Editor: Toll-like receptor 9 activation has been reported to be associated with many autoimmune diseases. DNA inhibition using oligodeoxynucleotides is one of the potential treatments. In this article, the authors described hydrogel-based platform for the delivery of the inhibitory oligodeoxynucleotides for enhanced efficacy. The positive findings could indicate a way for the future.