title: CNS amyloid-β, soluble APP-α and -β kinetics during BACE inhibition.
abstract: BACE, a β-secretase, is an attractive potential disease-modifying therapeutic strategy for Alzheimer's disease (AD) as it results directly in the decrease of amyloid precursor protein (APP) processing through the β-secretase pathway and a lowering of CNS amyloid-β (Aβ) levels. The interaction of the β-secretase and α-secretase pathway-mediated processing of APP in the rhesus monkey (nonhuman primate; NHP) CNS is not understood. We hypothesized that CNS inhibition of BACE would result in decreased newly generated Aβ and soluble APPβ (sAPPβ), with increased newly generated sAPPα. A stable isotope labeling kinetics experiment in NHPs was performed with a (13)C6-leucine infusion protocol to evaluate effects of BACE inhibition on CNS APP processing by measuring the kinetics of sAPPα, sAPPβ, and Aβ in CSF. Each NHP received a low, medium, or high dose of MBI-5 (BACE inhibitor) or vehicle in a four-way crossover design. CSF sAPPα, sAPPβ, and Aβ were measured by ELISA and newly incorporated label following immunoprecipitation and liquid chromatography-mass spectrometry. Concentrations, kinetics, and amount of newly generated APP fragments were calculated. sAPPβ and sAPPα kinetics were similar, but both significantly slower than Aβ. BACE inhibition resulted in decreased labeled sAPPβ and Aβ in CSF, without observable changes in labeled CSF sAPPα. ELISA concentrations of sAPPβ and Aβ both decreased and sAPPα increased. sAPPα increased by ELISA, with no difference by labeled sAPPα kinetics indicating increases in product may be due to APP shunting from the β-secretase to the α-secretase pathway. These results provide a quantitative understanding of pharmacodynamic effects of BACE inhibition on NHP CNS, which can inform about target development.
authors.affiliation: Departments of Neurology and.
authors.forename: Justyna A
authors.identifier: http://orcid.org/0000-0003-1718-147X
authors.initials: JA
authors.lastname: Dobrowolska
authors.affiliation: Safety and Laboratory Animal Resources.
authors.forename: Maria S
authors.initials: MS
authors.lastname: Michener
authors.affiliation: Molecular Biomarkers.
authors.forename: Guoxin
authors.initials: G
authors.lastname: Wu
authors.affiliation: Medicine, Washington University School of Medicine, St. Louis, Missouri 63110 and.
authors.forename: Bruce W
authors.initials: BW
authors.lastname: Patterson
authors.affiliation: Medicine, Washington University School of Medicine, St. Louis, Missouri 63110 and.
authors.forename: Robert
authors.initials: R
authors.lastname: Chott
authors.affiliation: Departments of Neurology and.
authors.forename: Vitaliy
authors.initials: V
authors.lastname: Ovod
authors.affiliation: Departments of Neurology and.
authors.forename: Yuriy
authors.initials: Y
authors.lastname: Pyatkivskyy
authors.affiliation: Departments of Neurology and.
authors.forename: Kristin R
authors.initials: KR
authors.lastname: Wildsmith
authors.affiliation: Departments of Neurology and.
authors.forename: Tom
authors.initials: T
authors.lastname: Kasten
authors.affiliation: Safety and Laboratory Animal Resources.
authors.forename: Parker
authors.initials: P
authors.lastname: Mathers
authors.affiliation: Safety and Laboratory Animal Resources.
authors.forename: Mandy
authors.initials: M
authors.lastname: Dancho
authors.affiliation: Safety and Laboratory Animal Resources.
authors.forename: Christina
authors.initials: C
authors.lastname: Lennox
authors.affiliation: Safety and Laboratory Animal Resources.
authors.forename: Brad E
authors.initials: BE
authors.lastname: Smith
authors.affiliation: Safety and Laboratory Animal Resources.
authors.forename: David
authors.initials: D
authors.lastname: Gilberto
authors.affiliation: Preclinical Drug Metabolism, Merck Research Laboratories, West Point, Pennsylvania 19486 and Kenilworth, New Jersey 07033.
authors.forename: Debra
authors.initials: D
authors.lastname: McLoughlin
authors.affiliation: Early Development Statistics, and.
authors.forename: Daniel J
authors.initials: DJ
authors.lastname: Holder
authors.affiliation: Medicinal Chemistry.
authors.forename: Andrew W
authors.initials: AW
authors.lastname: Stamford
authors.affiliation: Medicine, Washington University School of Medicine, St. Louis, Missouri 63110 and.
authors.forename: Kevin E
authors.initials: KE
authors.lastname: Yarasheski
authors.affiliation: Neuroscience.
authors.forename: Matthew E
authors.initials: ME
authors.lastname: Kennedy
authors.affiliation: Molecular Biomarkers.
authors.forename: Mary J
authors.initials: MJ
authors.lastname: Savage
authors.affiliation: Departments of Neurology and batemanr@wustl.edu.
authors.forename: Randall J
authors.initials: RJ
authors.lastname: Bateman
mesh_terms: D053829:Amyloid Precursor Protein Secretases / Q000134:cerebrospinal fluid* / Q000378:metabolism; D016229:Amyloid beta-Peptides / Q000134:cerebrospinal fluid* / Q000378:metabolism; D016564:Amyloid beta-Protein Precursor / Q000134:cerebrospinal fluid* / Q000378:metabolism; D000818:Animals; D002247:Carbon Isotopes / Q000378:metabolism; D045744:Cell Line, Tumor; D002490:Central Nervous System / Q000187:drug effects / Q000378:metabolism*; D018592:Cross-Over Studies; D004305:Dose-Response Relationship, Drug; D004791:Enzyme Inhibitors / Q000494:pharmacology; D006801:Humans; D047468:Immunoprecipitation; D007930:Leucine / Q000378:metabolism; D008253:Macaca mulatta; D013058:Mass Spectrometry; D009447:Neuroblastoma; D010446:Peptide Fragments; D014162:Transfection
chemical_list: D016229:Amyloid beta-Peptides; D016564:Amyloid beta-Protein Precursor; D002247:Carbon Isotopes; D004791:Enzyme Inhibitors; D010446:Peptide Fragments; D053829:Amyloid Precursor Protein Secretases; D007930:Leucine
keywords: BACE inhibitor; SILK; amyloid beta; amyloid precursor protein; sAPPα; sAPPβ