title: Amyloid beta peptides in human plasma and tissues and their significance for Alzheimer's disease.
abstract: BACKGROUND
  We evaluated the amounts of amyloid beta (Abeta)) peptides in the central nervous system (CNS) and in reservoirs outside the CNS and their potential impact on Abeta plasma levels and Alzheimer's disease (AD) pathology.
  
  
  METHODS
  Amyloid beta levels were measured in (1) the plasma of AD and nondemented (ND) controls in a longitudinal study, (2) the plasma of a cohort of AD patients receiving a cholinesterase inhibitor, and (3) the skeletal muscle, liver, aorta, platelets, leptomeningeal arteries, and in gray and white matter of AD and ND control subjects.
  
  
  RESULTS
  Plasma Abeta levels fluctuated over time and among individuals, suggesting continuous contributions from brain and peripheral tissues and associations with reactive circulating proteins. Arteries with atherosclerosis had larger amounts of Abeta40 than disease-free vessels. Inactivated platelets contained more Abeta peptides than activated ones. Substantially more Abeta was present in liver samples from ND patients. Overall, AD brain and skeletal muscle contained increased levels of Abeta.
  
  
  CONCLUSIONS
  Efforts to use plasma levels of Abeta peptides as AD biomarkers or disease-staging scales have failed. Peripheral tissues might contribute to both the circulating amyloid pool and AD pathology within the brain and its vasculature. The wide spread of plasma Abeta values is also due in part to the ability of Abeta to bind to a variety of plasma and membrane proteins. Sources outside the CNS must be accounted for because pharmacologic interventions to reduce cerebral amyloid are assessed by monitoring Abeta plasma levels. Furthermore, the long-range impact of Abeta immunotherapy on peripheral Abeta sources should also be considered.
authors.affiliation: The Longtine Center for Molecular Biology and Genetics, Sun Health Research Institute, Sun City, AZ, USA. alex.roher@bannerhealth.com
authors.forename: Alex E
authors.initials: AE
authors.lastname: Roher
authors.forename: Chera L
authors.initials: CL
authors.lastname: Esh
authors.forename: Tyler A
authors.initials: TA
authors.lastname: Kokjohn
authors.forename: Eduardo M
authors.initials: EM
authors.lastname: Castaño
authors.forename: Gregory D
authors.initials: GD
authors.lastname: Van Vickle
authors.forename: Walter M
authors.initials: WM
authors.lastname: Kalback
authors.forename: R Lyle
authors.initials: RL
authors.lastname: Patton
authors.forename: Dean C
authors.initials: DC
authors.lastname: Luehrs
authors.forename: Ian D
authors.initials: ID
authors.lastname: Daugs
authors.forename: Yu-Min
authors.initials: YM
authors.lastname: Kuo
authors.forename: Mark R
authors.initials: MR
authors.lastname: Emmerling
authors.forename: Holly
authors.initials: H
authors.lastname: Soares
authors.forename: Joseph F
authors.initials: JF
authors.lastname: Quinn
authors.forename: Jeffrey
authors.initials: J
authors.lastname: Kaye
authors.forename: Donald J
authors.initials: DJ
authors.lastname: Connor
authors.forename: Nina B
authors.initials: NB
authors.lastname: Silverberg
authors.forename: Charles H
authors.initials: CH
authors.lastname: Adler
authors.forename: James D
authors.initials: JD
authors.lastname: Seward
authors.forename: Thomas G
authors.initials: TG
authors.lastname: Beach
authors.forename: Marwan N
authors.initials: MN
authors.lastname: Sabbagh
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000544:Alzheimer Disease / Q000188:drug therapy / Q000378:metabolism* / Q000473:pathology*; D016229:Amyloid beta-Peptides / Q000097:blood* / Q000378:metabolism; D001011:Aorta / Q000378:metabolism; D015415:Biomarkers / Q000097:blood* / Q000378:metabolism; D001792:Blood Platelets / Q000378:metabolism; D001921:Brain / Q000378:metabolism*; D002800:Cholinesterase Inhibitors / Q000627:therapeutic use; D005260:Female; D006801:Humans; D008099:Liver / Q000378:metabolism; D008137:Longitudinal Studies; D008297:Male; D008576:Meningeal Arteries / Q000378:metabolism; D008875:Middle Aged; D018482:Muscle, Skeletal / Q000378:metabolism
chemical_list: D016229:Amyloid beta-Peptides; D015415:Biomarkers; D002800:Cholinesterase Inhibitors