Enhanced activity of immunosuppressive oligodeoxynucleotides by incorporating them into hexapod-like nanostructured DNA

Abstract

A151 and other immunosuppressive oligodeoxynucleotides that act as Toll-like receptor (TLR) 9 antagonists are candidate agents for the treatment of autoimmune and inflammatory diseases in which TLR9 activation leads to harmful immune responses. Their efficient delivery to TLR9-positive target cells will increase their potency, but few attempts have been made to enhance their delivery. We previously reported that hexapod-like nanostructured DNA (hexapodna) enhanced the activity of immunostimulatory cytosine-phosphate-guanine (CpG) DNA by efficiently delivering it to immune cells. In this study, to enhance the immunosuppressive activity of A151, we designed a hexapodna containing six copies of the complementary sequence to A151. Structural analyses showed that A151-loaded hexapodna (supHexapodna) was obtained as designed. CpG 1668, which is a typical synthetic CpG DNA, induced tumour necrosis factor-α release from mouse macrophage-like RAW264.7 cells, and supHexapodna inhibited this more efficiently than A151. A flow cytometric analysis showed that the uptake of Alexa Fluor 488-labelled A151 by RAW264.7 cells significantly increased when it was incorporated into supHexapodna, whereas the uptake of Alexa Fluor 488-labelled CpG 1668 was hardly affected by A151 or supHexapodna. These results suggest that the hexapodna-mediated delivery of A151 can increase the potency of its TLR9-inhibitory activity towards immune cells.