The DNA sugar backbone 2' deoxyribose determines toll-like receptor 9 activation.
CpG motifs within phosphorothioate (PS)-modified DNA drive Toll-like receptor 9 (TLR9) activation, but the rules governing recognition of natural phosphodiester (PD) DNA are less understood. Here, we showed that the sugar backbone determined DNA recognition by TLR9. Homopolymeric, base-free PD 2' deoxyribose acted as a basal TLR9 agonist as it bound to and activated TLR9. This effect was enhanced by DNA bases, even short of CpG motifs. In contrast, PS-modified 2' deoxyribose homopolymers acted as TLR9 and TLR7 antagonists. They displayed high affinity to both TLRs and did not activate on their own, but they competitively inhibited ligand-TLR interaction and activation. Although addition of random DNA bases to the PS 2' deoxyribose backbone did not alter these effects, CpG motifs transformed TLR9-inhibitory to robust TLR9-stimulatory activity. Our results identified the PD 2' deoxyribose backbone as an important determinant of TLR9 activation by natural DNA, restrict CpG-motif dependency of TLR9 activation to synthetic PS-modified ligands, and define PS-modified 2' deoxyribose as a prime effector of TLR9 and TLR7 inhibition.
Haas
Tobias
T
Institut für Medizinische Mikrobiologie, Immunologie und Hygiene, Technische Universität München, Trogerstrasse 30, 81675 München, Germany.
Metzger
Jochen
J
Schmitz
Frank
F
Heit
Antje
A
Müller
Thomas
T
Latz
Eicke
E
Wagner
Hermann
H
D000818:Animals; D004277:DNA, Single-Stranded / Q000737:chemistry* / Q000276:immunology*; D003713:Dendritic Cells / Q000276:immunology; D003855:Deoxyribose / Q000276:immunology*; D011992:Endosomes / Q000276:immunology; D005434:Flow Cytometry; D006801:Humans; D008297:Male; D008562:Membrane Glycoproteins / Q000276:immunology / Q000378:metabolism; D051379:Mice; D008810:Mice, Inbred C57BL; D008822:Mice, Transgenic; D009841:Oligonucleotides / Q000737:chemistry / Q000276:immunology; D046709:Pattern Recognition, Physiological; D051199:Toll-Like Receptor 7 / Q000276:immunology / Q000378:metabolism; D051217:Toll-Like Receptor 9 / Q000276:immunology*
D004277:DNA, Single-Stranded; D008562:Membrane Glycoproteins; D009841:Oligonucleotides; C477038:Tlr7 protein, mouse; C495370:Tlr9 protein, mouse; D051199:Toll-Like Receptor 7; D051217:Toll-Like Receptor 9; D003855:Deoxyribose