title: Bivalent Brain Shuttle Increases Antibody Uptake by Monovalent Binding to the Transferrin Receptor.
abstract: The blood-brain barrier (BBB) is an obstacle for antibody passage into the brain, impeding the development of immunotherapy and antibody-based diagnostics for brain disorders. In the present study, we have developed a brain shuttle for active transport of antibodies across the BBB by receptor-mediated transcytosis. We have thus recombinantly fused two single-chain variable fragments (scFv) of the transferrin receptor (TfR) antibody 8D3 to the light chains of mAb158, an antibody selectively binding to Aβ protofibrils, which are involved in the pathogenesis of Alzheimer's disease (AD). Despite the two TfR binders, a monovalent interaction with TfR was achieved due to the short linkers that sterically hinder bivalent binding to the TfR dimer. The design enabled efficient receptor-mediated brain uptake of the fusion protein. Two hours after administration, brain concentrations were 2-3% of the injected dose per gram brain, comparable to small molecular drugs and 80-fold higher than unmodified mAb158. After three days, fusion protein concentrations in AD transgenic mouse brains were 9-fold higher than in wild type mice, demonstrating highin vivospecificity. Thus, our innovative recombinant design markedly increases mAb158 brain uptake, which makes it a strong candidate for improved Aβ immunotherapy and as a PET radioligand for early diagnosis and evaluation of treatment effect in AD. Moreover, this approach could be applied to any target within the brain.
authors.affiliation: Department of Public Health and Caring Sciences/Geriatrics, Uppsala University, Rudbeck Laboratory, 75185 Uppsala, Sweden.
authors.forename: Greta
authors.initials: G
authors.lastname: Hultqvist
authors.affiliation: Department of Public Health and Caring Sciences/Geriatrics, Uppsala University, Rudbeck Laboratory, 75185 Uppsala, Sweden.
authors.forename: Stina
authors.initials: S
authors.lastname: Syvänen
authors.affiliation: Department of Public Health and Caring Sciences/Geriatrics, Uppsala University, Rudbeck Laboratory, 75185 Uppsala, Sweden.
authors.forename: Xiaotian T
authors.initials: XT
authors.lastname: Fang
authors.affiliation: Department of Public Health and Caring Sciences/Geriatrics, Uppsala University, Rudbeck Laboratory, 75185 Uppsala, Sweden.
authors.forename: Lars
authors.initials: L
authors.lastname: Lannfelt
authors.affiliation: Department of Public Health and Caring Sciences/Geriatrics, Uppsala University, Rudbeck Laboratory, 75185 Uppsala, Sweden.
authors.forename: Dag
authors.initials: D
authors.lastname: Sehlin
mesh_terms: D000544:Alzheimer Disease / Q000628:therapy*; D000818:Animals; D000906:Antibodies / Q000235:genetics / Q000378:metabolism*; D001812:Blood-Brain Barrier / Q000378:metabolism*; D001923:Brain Chemistry; D004195:Disease Models, Animal; D007167:Immunotherapy / Q000379:methods; D051379:Mice; D008822:Mice, Transgenic; D018696:Neuroprotective Agents / Q000008:administration & dosage / Q000493:pharmacokinetics*; D011990:Receptors, Transferrin / Q000378:metabolism*; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism
chemical_list: D000906:Antibodies; D018696:Neuroprotective Agents; D011990:Receptors, Transferrin; D011994:Recombinant Proteins
keywords: BBB shuttle /TfR /antibodies / Alzheimer's disease/ immunotherapy/PET.