title: Modification of an exposed loop in the C1 domain reduces immune responses to factor VIII in hemophilia A mice.
abstract: Development of neutralizing Abs to blood coagulation factor VIII (FVIII) provides a major complication in hemophilia care. In this study we explored whether modulation of the uptake of FVIII by APCs can reduce its intrinsic immunogenicity. Endocytosis of FVIII by professional APCs is significantly blocked by mAb KM33, directed toward the C1 domain of FVIII. We created a C1 domain variant (FVIII-R2090A/K2092A/F2093A), which showed only minimal binding to KM33 and retained its activity as measured by chromogenic assay. FVIII-R2090A/K2092A/F2093A displayed a strongly reduced internalization by human monocyte-derived dendritic cells and macrophages, as well as murine BM-derived dendritic cells. We subsequently investigated the ability of this variant to induce an immune response in FVIII-deficient mice. We show that mice treated with FVIII-R2090A/K2092A/F2093A have significantly lower anti-FVIII Ab titers and FVIII-specific CD4(+) T-cell responses compared with mice treated with wild-type FVIII. These data show that alanine substitutions at positions 2090, 2092, and 2093 reduce the immunogenicity of FVIII. According to our findings we hypothesize that FVIII variants displaying a reduced uptake by APCs provide a novel therapeutic approach to reduce inhibitor development in hemophilia A.
authors.affiliation: Department of Plasma Proteins, Sanquin-AMC Landsteiner Laboratory and Van Creveld Laboratory, Amsterdam, The Netherlands.
authors.forename: Aleksandra
authors.initials: A
authors.lastname: Wroblewska
authors.forename: Simon D
authors.initials: SD
authors.lastname: van Haren
authors.forename: Eszter
authors.initials: E
authors.lastname: Herczenik
authors.forename: Paul
authors.initials: P
authors.lastname: Kaijen
authors.forename: Aleksandra
authors.initials: A
authors.lastname: Ruminska
authors.forename: Sheng-Yu
authors.initials: SY
authors.lastname: Jin
authors.forename: X Long
authors.initials: XL
authors.lastname: Zheng
authors.forename: Maartje
authors.initials: M
authors.lastname: van den Biggelaar
authors.forename: Anja
authors.initials: A
authors.lastname: ten Brinke
authors.forename: Alexander B
authors.initials: AB
authors.lastname: Meijer
authors.forename: Jan
authors.initials: J
authors.lastname: Voorberg
mesh_terms: D019943:Amino Acid Substitution; D000818:Animals; D057134:Antibodies, Neutralizing / Q000276:immunology*; D001323:Autoantibodies / Q000276:immunology*; D019774:Blood Coagulation Factor Inhibitors / Q000276:immunology*; D015496:CD4-Positive T-Lymphocytes / Q000276:immunology; D003713:Dendritic Cells / Q000276:immunology*; D004195:Disease Models, Animal; D005169:Factor VIII / Q000235:genetics / Q000276:immunology* / Q000494:pharmacology; D006467:Hemophilia A / Q000188:drug therapy / Q000276:immunology*; D006801:Humans; D008264:Macrophages / Q000276:immunology*; D051379:Mice; D018345:Mice, Knockout; D009000:Monocytes / Q000276:immunology*; D020125:Mutation, Missense; D017434:Protein Structure, Tertiary
chemical_list: D057134:Antibodies, Neutralizing; D001323:Autoantibodies; D019774:Blood Coagulation Factor Inhibitors; C078147:F8 protein, human; D005169:Factor VIII