title: Vascular alterations in PDAPP mice after anti-Aβ immunotherapy: Implications for amyloid-related imaging abnormalities.
abstract: BACKGROUND
  Clinical studies of β-amyloid (Aβ) immunotherapy in Alzheimer's disease (AD) patients have demonstrated reduction of central Aβ plaque by positron emission tomography (PET) imaging and the appearance of amyloid-related imaging abnormalities (ARIA). To better understand the relationship between ARIA and the pathophysiology of AD, we undertook a series of studies in PDAPP mice evaluating vascular alterations in the context of central Aβ pathology and after anti-Aβ immunotherapy.
  
  
  METHODS
  We analyzed PDAPP mice treated with either 3 mg/kg/week of 3D6, the murine form of bapineuzumab, or isotype control antibodies for periods ranging from 1 to 36 weeks and evaluated the vascular alterations in the context of Aβ pathology and after anti-Aβ immunotherapy. The number of mice in each treatment group ranged from 26 to 39 and a total of 345 animals were analyzed.
  
  
  RESULTS
  The central vasculature displayed morphological abnormalities associated with vascular Aβ deposits. Treatment with 3D6 antibody induced clearance of vascular Aβ that was spatially and temporally associated with a transient increase in microhemorrhage and in capillary Aβ deposition. Microhemorrhage resolved over a time period that was associated with a recovery of vascular morphology and a decrease in capillary Aβ accumulation.
  
  
  CONCLUSIONS
  These data suggest that vascular leakage events, such as microhemorrhage, may be related to the removal of vascular Aβ. With continued treatment, this initial susceptibility period is followed by restoration of vascular morphology and reduced vulnerability to further vascular leakage events. The data collectively suggested a vascular amyloid clearance model of ARIA, which accounts for the currently known risk factors for the incidence of ARIA in clinical studies.
authors.affiliation: Janssen Alzheimer Immunotherapy Research & Development, South San Francisco, CA, USA.
authors.forename: Wagner
authors.initials: W
authors.lastname: Zago
authors.forename: Sally
authors.initials: S
authors.lastname: Schroeter
authors.forename: Teresa
authors.initials: T
authors.lastname: Guido
authors.forename: Karen
authors.initials: K
authors.lastname: Khan
authors.forename: Peter
authors.initials: P
authors.lastname: Seubert
authors.forename: Ted
authors.initials: T
authors.lastname: Yednock
authors.forename: Dale
authors.initials: D
authors.lastname: Schenk
authors.forename: Keith M
authors.initials: KM
authors.lastname: Gregg
authors.forename: Dora
authors.initials: D
authors.lastname: Games
authors.forename: Frédérique
authors.initials: F
authors.lastname: Bard
authors.forename: Gene G
authors.initials: GG
authors.lastname: Kinney
mesh_terms: D000544:Alzheimer Disease / Q000235:genetics / Q000276:immunology / Q000473:pathology / Q000628:therapy*; D016229:Amyloid beta-Peptides / Q000276:immunology*; D016564:Amyloid beta-Protein Precursor / Q000235:genetics; D000818:Animals; D061067:Antibodies, Monoclonal, Humanized / Q000627:therapeutic use*; D051401:Aquaporin 4 / Q000378:metabolism; D001808:Blood Vessels / Q000378:metabolism / Q000473:pathology* / Q000648:ultrastructure; D001921:Brain / Q000473:pathology*; D024141:Collagen Type IV / Q000378:metabolism; D004195:Disease Models, Animal; D005786:Gene Expression Regulation / Q000187:drug effects; D005904:Glial Fibrillary Acidic Protein / Q000378:metabolism; D020300:Intracranial Hemorrhages / Q000209:etiology; D008578:Meninges / Q000473:pathology / Q000648:ultrastructure; D051379:Mice; D008822:Mice, Transgenic; D046529:Microscopy, Electron, Transmission; D009154:Mutation / Q000235:genetics; D013997:Time Factors
chemical_list: D016229:Amyloid beta-Peptides; D016564:Amyloid beta-Protein Precursor; D061067:Antibodies, Monoclonal, Humanized; C496031:Aqp4 protein, mouse; D051401:Aquaporin 4; D024141:Collagen Type IV; D005904:Glial Fibrillary Acidic Protein; C545458:bapineuzumab
keywords: ARIA; Immunotherapy; Microhemorrhage; Vascular amyloid