Novel immunostimulatory agent based on CpG oligodeoxynucleotide linked to the nontoxic B subunit of cholera toxin.
In this study, we report the development of a novel, rationally designed immunostimulatory adjuvant based on chemical conjugation of CpG oligodeoxynucleotide (ODN) to the nontoxic B subunit of cholera toxin (CTB). We demonstrate that the immunostimulatory effects of CpG can be dramatically enhanced by conjugation to CTB. Thus, CpG ODN linked to CTB (CTB-CpG) was shown to be a more potent stimulator of proinflammatory cytokine and chemokine responses in murine splenocytes and human PBMCs than those of CpG ODN alone in vitro. The presence of CpG motif, but not modified phosphorothioate ODN backbone, was found to be critical for the enhanced immunostimulatory effects of CTB-CpG. Our mode-of-action studies, including studies on cells from specifically gene knockout mice suggest that similar to CpG, CTB-CpG exerts its immunostimulatory effects through a TLR9/MyD88- and NF-kappaB-dependent pathway. Surprisingly, and as opposed to CpG ODN, CTB-CpG-induced immunity was shown to be independent of endosomal acidification and resistant to inhibitory ODN. Furthermore, preincubation of CTB-CpG with GM1 ganglioside reduced the immunostimulatory effects of CTB-CpG to those of CpG ODN alone. Interestingly, conjugation of CpG ODN to CTB confers an enhanced cross-species activity to CpG ODN. Furthermore, using tetanus toxoid as a vaccine Ag for s.c. immunization, CTB-CpG markedly enhanced the Ag-specific IgG Ab response and altered the specific pattern of Ab isotypes toward a Th1 type response. To our knowledge, CTB is the first nontoxic derivative of microbial toxins discovered that when chemically linked to CpG remarkably augments the CpG-mediated immune responses.
Adamsson
Jenni
J
Department of Medical Microbiology and Immunology, Göteborg University Vaccine Research Institute, Göteborg University, Göteborg, Sweden.
Lindblad
Marianne
M
Lundqvist
Annika
A
Kelly
Denise
D
Holmgren
Jan
J
Harandi
Ali M
AM
D048868:Adaptor Proteins, Signal Transducing / Q000378:metabolism; D000276:Adjuvants, Immunologic / Q000737:chemistry / Q000235:genetics / Q000494:pharmacology*; D000818:Animals; D001483:Base Sequence; D018925:Chemokines / Q000096:biosynthesis; D002772:Cholera Toxin / Q000737:chemistry / Q000235:genetics / Q000494:pharmacology*; D016207:Cytokines / Q000096:biosynthesis; D015195:Drug Design; D011992:Endosomes / Q000187:drug effects / Q000378:metabolism; D005677:G(M1) Ganglioside / Q000494:pharmacology; D006801:Humans; D006863:Hydrogen-Ion Concentration; D018796:Immunoconjugates / Q000737:chemistry / Q000235:genetics / Q000494:pharmacology; D066298:In Vitro Techniques; D007963:Leukocytes, Mononuclear / Q000187:drug effects / Q000276:immunology; D051379:Mice; D008809:Mice, Inbred C3H; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D053594:Myeloid Differentiation Factor 88; D016328:NF-kappa B / Q000378:metabolism; D009838:Oligodeoxyribonucleotides / Q000737:chemistry / Q000235:genetics / Q000494:pharmacology*; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics / Q000494:pharmacology; D013045:Species Specificity; D051217:Toll-Like Receptor 9 / Q000378:metabolism
D048868:Adaptor Proteins, Signal Transducing; D000276:Adjuvants, Immunologic; C408982:CPG-oligonucleotide; D018925:Chemokines; D016207:Cytokines; D018796:Immunoconjugates; C507779:MYD88 protein, human; C507780:Myd88 protein, mouse; D053594:Myeloid Differentiation Factor 88; D016328:NF-kappa B; D009838:Oligodeoxyribonucleotides; D011994:Recombinant Proteins; D051217:Toll-Like Receptor 9; D005677:G(M1) Ganglioside; D002772:Cholera Toxin; D019869:Phosphatidylinositol 3-Kinases