title: The immunostimulatory activity of phosphorothioate CpG oligonucleotides is affected by distal sequence changes.
abstract: CpG motifs in bacterial DNA activate innate immune cells via toll like receptor 9 (TLR9). Short synthetic oligodeoxynucleotides (ODN) containing a six base CpG motif can mimic the immunostimulatory activity of bacterial DNA. Phosphorothioate (PS) modification of the backbone of ODN makes them more resistant to nuclease degradation and consequently preferable for therapeutic use. Previous studies have shown that the sequence requirements for PS-ODN to have maximal stimulatory activity are more stringent than for normal phosphodiester (PO) ODN. Here we show small sequence changes distal to the CpG motif can affect the activity of PS-ODN whilst having no effect on the activity of PO-ODN. The addition of terminal dG residues and other minor changes to the potently immunostimulatory PS-ODN 1668S caused delayed signalling. The reduction in immunostimulatory activity of PS-ODN was associated with a delay in the activation of MAP kinases.
authors.affiliation: The University of Queensland, Institute for Molecular Bioscience, Qld 4072, Australia. Tara.Roberts@qimr.edu.au
authors.forename: Tara L
authors.initials: TL
authors.lastname: Roberts
authors.forename: Jasmyn A
authors.initials: JA
authors.lastname: Dunn
authors.forename: Matthew J
authors.initials: MJ
authors.lastname: Sweet
authors.forename: David A
authors.initials: DA
authors.lastname: Hume
authors.forename: Katryn J
authors.initials: KJ
authors.lastname: Stacey
mesh_terms: D000276:Adjuvants, Immunologic / Q000235:genetics; D000818:Animals; D001483:Base Sequence; D015153:Blotting, Western; D002460:Cell Line; D002478:Cells, Cultured; D018899:CpG Islands / Q000235:genetics*; D004305:Dose-Response Relationship, Drug; D006801:Humans; D008264:Macrophages / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D051379:Mice; D008807:Mice, Inbred BALB C; D008810:Mice, Inbred C57BL; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D054735:Phosphorothioate Oligonucleotides / Q000235:genetics* / Q000493:pharmacokinetics / Q000494:pharmacology*; D010766:Phosphorylation / Q000187:drug effects; D015398:Signal Transduction / Q000187:drug effects; D013997:Time Factors
chemical_list: D000276:Adjuvants, Immunologic; D054735:Phosphorothioate Oligonucleotides; D020928:Mitogen-Activated Protein Kinases