title: Novel oligodeoxynucleotide agonists of TLR9 containing N3-Me-dC or N1-Me-dG modifications.
abstract: Synthetic oligodeoxynucleotides containing unmethylated CpG motifs activate Toll-Like Receptor 9 (TLR9). Our previous studies have shown the role of hydrogen-bond donor and acceptor groups of cytosine and guanine in the CpG motif and identified synthetic immunostimulatory motifs. In the present study to elucidate the significance of N3-position of cytosine and N1-position of guanine in the CpG motif, we substituted C or G of a CpG dinucleotide with N3-Me-cytosine or N1-Me-guanine, respectively, in immunomodulatory oligodeoxynucleotides (IMOs). IMOs containing N-Me-cytosine or N-Me-guanine in C- or G-position, respectively, of the CpG dinucleotide showed activation of HEK293 cells expressing TLR9, but not TLR3, 7 or 8. IMOs containing N-Me-cytosine or N-Me-guanine modification showed activity in mouse spleen cell cultures, in vivo in mice, and in human cell cultures. In addition, IMOs containing N-Me-substitutions reversed antigen-induced Th2 immune responses towards a Th1-type in OVA-sensitized mouse spleen cell cultures. These studies suggest that TLR9 tolerates a methyl group at N1-position of G and a methyl group at N3-position of C may interfere with TLR9 activation to some extent. These are the first studies elucidating the role of N3-position of cytosine and N1-position of guanine in a CpG motif for TLR9 activation and immune stimulation.
authors.affiliation: Idera Pharmaceuticals, Inc. 345 Vassar Street, Cambridge, MA 02139, USA.
authors.forename: Mallikarjuna Reddy
authors.initials: MR
authors.lastname: Putta
authors.forename: FuGang
authors.initials: F
authors.lastname: Zhu
authors.forename: Yukui
authors.initials: Y
authors.lastname: Li
authors.forename: Lakshmi
authors.initials: L
authors.lastname: Bhagat
authors.forename: YanPing
authors.initials: Y
authors.lastname: Cong
authors.forename: Ekambar R
authors.initials: ER
authors.lastname: Kandimalla
authors.forename: Sudhir
authors.initials: S
authors.lastname: Agrawal
mesh_terms: D000276:Adjuvants, Immunologic / Q000138:chemical synthesis / Q000737:chemistry* / Q000494:pharmacology*; D000818:Animals; D001402:B-Lymphocytes / Q000187:drug effects / Q000276:immunology; D002460:Cell Line; D002478:Cells, Cultured; D018899:CpG Islands; D016207:Cytokines / Q000096:biosynthesis; D003845:Deoxycytosine Nucleotides / Q000737:chemistry; D003848:Deoxyguanine Nucleotides / Q000737:chemistry; D005260:Female; D006801:Humans; D008213:Lymphocyte Activation; D051379:Mice; D008807:Mice, Inbred BALB C; D008810:Mice, Inbred C57BL; D009838:Oligodeoxyribonucleotides / Q000138:chemical synthesis / Q000737:chemistry* / Q000494:pharmacology*; D013154:Spleen / Q000166:cytology / Q000276:immunology; D013163:Splenomegaly / Q000139:chemically induced; D018417:Th1 Cells / Q000276:immunology; D051217:Toll-Like Receptor 9 / Q000819:agonists*
chemical_list: D000276:Adjuvants, Immunologic; D016207:Cytokines; D003845:Deoxycytosine Nucleotides; D003848:Deoxyguanine Nucleotides; D009838:Oligodeoxyribonucleotides; C495370:Tlr9 protein, mouse; D051217:Toll-Like Receptor 9