title: Reversal of lysosomal storage in brain of adult MPS-I mice with intravenous Trojan horse-iduronidase fusion protein.
abstract: A mouse model of mucopolysaccharidosis (MPS) type I, which is null for the lysosomal enzyme, α-L-iduronidase (IDUA), is treated with intravenous, receptor-mediated enzyme replacement therapy of the brain. Murine IDUA, which does not cross the blood-brain barrier, is re-engineered for targeting to the brain as an IgG-enzyme fusion protein. The amino terminus of mature IDUA is fused to the carboxyl terminus of the heavy chain of a chimeric monoclonal antibody (mAb) against the murine transferrin receptor (TfR), and this fusion protein is designated cTfRMAb-IDUA. The cTfRMAb part of the fusion protein acts as a molecular Trojan horse to ferry the fused IDUA across the BBB and neuronal cell membrane via transport on the TfR. The IDUA enzyme activity of the fusion protein, 776 ± 79 units/μg protein, is comparable to recombinant IDUA. MPSI null mice, 6-8 months of age, were treated iv twice a week for 8 weeks with either saline or 1 mg/kg cTfRMAb-IDUA. The glycosoaminoglycan levels in liver, spleen, heart, and kidney were reduced by >95%, 80%, 36%, and 20%, respectively. Lysosomal inclusion bodies in the brain were quantitated from semithin sections stained with o-toluidine blue and normalized per 100 nucleoli per brain section. Treatment of the MPSI mice with the cTfRMAb-IDUA reduced intracellular lysosomal inclusion bodies by 73% in brain, as compared to the MPSI mice treated with saline. In conclusion, the reversal of pre-existing neural pathology in the brain of MPSI mice is possible with receptor-mediated enzyme replacement therapy of the brain.
authors.affiliation: Department of Medicine, UCLA, Los Angeles, California 90024, USA.
authors.forename: Ruben J
authors.initials: RJ
authors.lastname: Boado
authors.forename: Eric Ka-Wai
authors.initials: EK
authors.lastname: Hui
authors.forename: Jeff Zhiqiang
authors.initials: JZ
authors.lastname: Lu
authors.forename: Qing-Hui
authors.initials: QH
authors.lastname: Zhou
authors.forename: William M
authors.initials: WM
authors.lastname: Pardridge
mesh_terms: D016475:3T3 Cells; D000818:Animals; D000911:Antibodies, Monoclonal / Q000235:genetics / Q000378:metabolism*; D001812:Blood-Brain Barrier / Q000378:metabolism; D015153:Blotting, Western; D001921:Brain / Q000187:drug effects / Q000378:metabolism* / Q000473:pathology; D019556:COS Cells; D002522:Chlorocebus aethiops; D004591:Electrophoresis, Polyacrylamide Gel; D004797:Enzyme-Linked Immunosorbent Assay; D006025:Glycosaminoglycans / Q000378:metabolism; D007068:Iduronidase / Q000235:genetics / Q000378:metabolism*; D051379:Mice; D008059:Mucopolysaccharidosis I / Q000188:drug therapy*; D011990:Receptors, Transferrin / Q000276:immunology / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism* / Q000627:therapeutic use*
chemical_list: D000911:Antibodies, Monoclonal; D006025:Glycosaminoglycans; D011990:Receptors, Transferrin; D011993:Recombinant Fusion Proteins; D007068:Iduronidase