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Clearance of Alzheimer’s amyloid-β1-40 peptide from brain by LDL receptor–related protein-1 at the blood-brain barrier
Masayoshi Shibata, … , Jorge Ghiso, Berislav V. Zlokovic
Masayoshi Shibata, … , Jorge Ghiso, Berislav V. Zlokovic
Published December 15, 2000
Citation Information: J Clin Invest. 2000;106(12):1489-1499. https://doi.org/10.1172/JCI10498.
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Article

Clearance of Alzheimer’s amyloid-β1-40 peptide from brain by LDL receptor–related protein-1 at the blood-brain barrier

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Abstract

Elimination of amyloid-β peptide (Aβ) from the brain is poorly understood. After intracerebral microinjections in young mice, 125I-Aβ1-40 was rapidly removed from the brain (t1/2 ≤ 25 minutes), mainly by vascular transport across the blood-brain barrier (BBB). The efflux transport system for Aβ1-40 at the BBB was half saturated at 15.3 nM, and the maximal transport capacity was reached between 70 nM and 100 nM. Aβ1-40 clearance was substantially inhibited by the receptor-associated protein, and by antibodies against LDL receptor–related protein-1 (LRP-1) and α2-macroglobulin (α2M). As compared to adult wild-type mice, clearance was significantly reduced in young and old apolipoprotein E (apoE) knockout mice, and in old wild-type mice. There was no evidence that Aβ was metabolized in brain interstitial fluid and degraded to smaller peptide fragments and amino acids before its transport across the BBB into the circulation. LRP-1, although abundant in brain microvessels in young mice, was downregulated in older animals, and this downregulation correlated with regional Aβ accumulation in brains of Alzheimer’s disease (AD) patients. We conclude that the BBB removes Aβ from the brain largely via age-dependent, LRP-1–mediated transport that is influenced by α2M and/or apoE, and may be impaired in AD.

Authors

Masayoshi Shibata, Shinya Yamada, S. Ram Kumar, Miguel Calero, James Bading, Blas Frangione, David M. Holtzman, Carol A. Miller, Dudley K. Strickland, Jorge Ghiso, Berislav V. Zlokovic

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Figure 3

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(a) Brain TCA-precipitable (open bars) and non–TCA-precipitable 125I rad...
(a) Brain TCA-precipitable (open bars) and non–TCA-precipitable 125I radioactivity (solid bars) after intracerebral microinjections of 125I-Aβ1-40 (60 nM) into the caudate nucleus in mice, expressed as a percentage of total 125I radioactivity in the brain; mean ± SD of three to five animals. (b) Left panel shows HPLC elution profile of brain tissue 60 minutes after intracerebral microinjection of 125I-Aβ1-40 (60 nM). Separation was performed for 30 mg of brain tissue on a reverse-phase HPLC column, using a 30-minute linear gradient of 25–83% acetonitrile in 0.1% TFA, pH 2. 125I-Aβ1-40 eluted at 52%, corresponding to the elution time of Aβ1-40 standard. Right panel shows SDS-PAGE analysis of brain tissue supernatant at 30 minutes (lane 1) and 60 minutes (lane 2) after intracerebral microinjection of 125I-Aβ1-40 (60 nM). The radioactivity in the brain eluted as a single peak on HPLC, with the same retention time as the Aβ1-40 standard (data not shown). Aliquots of lyophilized sample were subjected to 10% Tris-tricine SDS-PAGE, transferred to a nitrocellulose membrane, and exposed to x-ray film. (c) Plasma TCA-precipitable (open bars) and non–TCA-precipitable 125I radioactivity (filled bars) after intracerebral microinjections of 125I-Aβ1-40 (60 nM) into the caudate nucleus in mice, expressed as a percentage of total 125I radioactivity in plasma; mean ± SD of three to five animals.

Copyright © 2023 American Society for Clinical Investigation
ISSN: 0021-9738 (print), 1558-8238 (online)

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