title: Immune tolerance induction to factor IX through B cell gene transfer: TLR9 signaling delineates between tolerogenic and immunogenic B cells.
abstract: A subset of patients with severe hemophilia B, the X-linked bleeding disorder resulting from absence of coagulation factor IX (FIX), develop pathogenic antibody responses during replacement therapy. These inhibitors block standard therapy and are often associated with anaphylactic reactions to FIX. Established clinical immune tolerance induction protocols often fail for FIX inhibitors. In a murine model of this immune complication, retrovirally transduced primary B cells expressing FIX antigen fused with immunoglobulin-G heavy chain prevented antibody formation to FIX and was also highly effective in desensitizing animals with preexisting response. In contrast, transplant of B cells that received the identical expression cassette via nucleofection of plasmid vector substantially heightened antibody formation against FIX, a response that could be blocked by toll-like receptor 9 (TLR9) inhibition. While innate responses to TLR4 activation or to retrovirus were minimal in B cells, plasmid DNA activated TLR9, resulting in CpG-dependent NF-κB activation/IL-6 expression and adaptor protein 3 dependent, CpG-independent induction of IFN-I. Neither response was seen in TLR9-deficient B cells. Therefore, TLR9 signaling in B cells, in particular in response to plasmid vector, is highly immunogenic and has to be avoided in design of tolerance protocols.
authors.affiliation: Department of Pediatrics, University of Florida, Gainesville, Florida, USA. Electronic address: wangxiaomei@ufl.edu.
authors.forename: Xiaomei
authors.initials: X
authors.lastname: Wang
authors.affiliation: Department of Pediatrics, University of Miami, Miami, Florida, USA.
authors.forename: Babak
authors.initials: B
authors.lastname: Moghimi
authors.affiliation: Department of Pediatrics, University of Florida, Gainesville, Florida, USA.
authors.forename: Irene
authors.initials: I
authors.lastname: Zolotukhin
authors.affiliation: Department of Pathology, Immunology and Laboratory Medicine, University of Florida, Gainesville, Florida, USA.
authors.forename: Laurence M
authors.initials: LM
authors.lastname: Morel
authors.affiliation: Department of Pediatrics, University of Florida, Gainesville, Florida, USA.
authors.forename: Ou
authors.initials: O
authors.lastname: Cao
authors.affiliation: Department of Pediatrics, University of Florida, Gainesville, Florida, USA. Electronic address: rherzog@ufl.edu.
authors.forename: Roland W
authors.initials: RW
authors.lastname: Herzog
mesh_terms: D019264:Adoptive Transfer / Q000379:methods; D000818:Animals; D001402:B-Lymphocytes / Q000276:immunology* / Q000378:metabolism; D002478:Cells, Cultured; D004195:Disease Models, Animal; D005164:Factor IX / Q000235:genetics / Q000378:metabolism*; D015316:Genetic Therapy / Q000379:methods*; D002836:Hemophilia B / Q000276:immunology / Q000628:therapy*; D006801:Humans; D007108:Immune Tolerance; D007113:Immunity, Innate / Q000276:immunology; D051379:Mice; D008810:Mice, Inbred C57BL; D010957:Plasmids / Q000235:genetics* / Q000378:metabolism; D012190:Retroviridae / Q000235:genetics* / Q000378:metabolism; D015398:Signal Transduction; D013154:Spleen / Q000166:cytology; D051217:Toll-Like Receptor 9 / Q000378:metabolism*; D014161:Transduction, Genetic / Q000379:methods; D014162:Transfection / Q000379:methods
chemical_list: C495371:TLR9 protein, human; D051217:Toll-Like Receptor 9; D005164:Factor IX