title: CpG ODN nanorings induce IFNα from plasmacytoid dendritic cells and demonstrate potent vaccine adjuvant activity.
abstract: CpG oligodeoxynucleotides (ODN) are short single-stranded synthetic DNA molecules that activate the immune system and have been found to be effective for preventing and treating infectious diseases, allergies, and cancers. Structurally distinct classes of synthetic ODN expressing CpG motifs differentially activate human immune cells. K-type ODN (K-ODN), which have progressed into human clinical trials as vaccine adjuvants and immunotherapeutic agents, are strong activators of B cells and trigger plasmacytoid dendritic cells (pDCs) to differentiate and produce tumor necrosis factor-α (TNFα). In contrast, D-type ODN (D-ODN) stimulate large amounts of interferon-α (IFNα) secretion from pDCs. This activity depends on the ability of D-ODN to adopt nanometer-sized G quadruplex-based structures, complicating their manufacturing and hampering their progress into the clinic. In search of a D-ODN substitute, we attempted to multimerize K-ODN into stable nanostructures using cationic peptides. We show that short ODN with a rigid secondary structure form nuclease-resistant nanorings after condensation with the HIV-derived peptide Tat(47-57). The nanorings enhanced cellular internalization, targeted the ODN to early endosomes, and induced a robust IFNα response from human pDCs. Compared to the conventional K-ODN, nanorings boosted T helper 1-mediated immune responses in mice immunized with the inactivated foot and mouth disease virus vaccine and generated superior antitumor immunity when used as a therapeutic tumor vaccine adjuvant in C57BL/6 mice bearing ovalbumin-expressing EG.7 thymoma tumors. These results suggest that the nanorings can act as D-ODN surrogates and may find a niche for further clinical applications.
authors.affiliation: Department of Biological Sciences, Middle East Technical University, 06800 Ankara, Turkey.
authors.forename: Bilgi
authors.initials: B
authors.lastname: Gungor
authors.forename: Fuat Cem
authors.initials: FC
authors.lastname: Yagci
authors.forename: Gizem
authors.initials: G
authors.lastname: Tincer
authors.forename: Banu
authors.initials: B
authors.lastname: Bayyurt
authors.forename: Esin
authors.initials: E
authors.lastname: Alpdundar
authors.forename: Soner
authors.initials: S
authors.lastname: Yildiz
authors.forename: Mine
authors.initials: M
authors.lastname: Ozcan
authors.forename: Ihsan
authors.initials: I
authors.lastname: Gursel
authors.forename: Mayda
authors.initials: M
authors.lastname: Gursel
mesh_terms: D000276:Adjuvants, Immunologic / Q000494:pharmacology*; D000595:Amino Acid Sequence; D000818:Animals; D018899:CpG Islands; D003713:Dendritic Cells / Q000276:immunology / Q000378:metabolism*; D016898:Interferon-alpha / Q000096:biosynthesis*; D051379:Mice; D008969:Molecular Sequence Data; D049329:Nanostructures; D009838:Oligodeoxyribonucleotides / Q000737:chemistry / Q000494:pharmacology*; D014765:Viral Vaccines / Q000276:immunology*
chemical_list: D000276:Adjuvants, Immunologic; D016898:Interferon-alpha; D009838:Oligodeoxyribonucleotides; D014765:Viral Vaccines