9173910

pubmed:Citation

1

Patients with trisomy 21 [Down syndrome (DS)] progressively develop amyloid beta-protein (A beta) deposits and then other features of Alzheimer's disease (AD), apparently due to increased gene dosage and thus expression of the beta-amyloid precursor protein. Because the neuropathological phenotype in older DS subjects closely resembles that of AD, the examination of DS brains of increasing age provides a unique model of the progression of AD. Here, we characterized the deposition of several A beta peptides and apolipoprotein E in formalin-fixed brain sections from 29 DS subjects between 3 and 73 years old. Amyloid plaque number and the percentage of cortical area they occupied were quantified by computerized image analysis. A beta ending at amino acid 42 (A beta 42) was the earliest form of A beta deposited in DS cortex. It was observed in 7 of 16 young (3-30 years) subjects, with the earliest deposition occurring at age 12. A beta ending at residue 40 (A beta 40) was not detected until approximately age 30, a time when degenerating neurites around A beta immunoreactive (IR) plaques were first observed, and the frequency of A beta 40 IR plaques then rose with age. Even in old (51-73 years) DS subjects, A beta 42 IR plaques were always more abundant than A beta 40 IR plaques. A beta peptides starting at aspartate 1 or pyroglutamate 3 were detected in small subsets of compacted, neuritic plaques beginning around age 30 and rose with age, the latter species always exceeding the former. Thus, the N-termini of the A beta 42 peptides abundantly deposited in very young DS subjects remain unknown. Apo E was detectable in a small subset of A beta 42 IR plaques beginning at age 12 and rose steadily with age; it clearly followed the deposition of A beta. Our analysis of very young DS brains suggests that amyloid plaque formation begins with A beta 42-ending peptides, and the number and percentage of cortical area of A beta 42 plaques increase very little with advancing age, while other heterogeneous A beta species and Apo E progressively accrue onto plaques containing A beta 42.

eng

IM

MEDLINE

0969-9961

Print

NLM

16-32

pubmed-meshheading:9173910-Adolescent, pubmed-meshheading:9173910-Adult, pubmed-meshheading:9173910-Aged, pubmed-meshheading:9173910-Aging, pubmed-meshheading:9173910-Alzheimer Disease, pubmed-meshheading:9173910-Amyloid beta-Peptides, pubmed-meshheading:9173910-Amyloid beta-Protein Precursor, pubmed-meshheading:9173910-Apolipoproteins E, pubmed-meshheading:9173910-Child, pubmed-meshheading:9173910-Child, Preschool, pubmed-meshheading:9173910-Down Syndrome, pubmed-meshheading:9173910-Female, pubmed-meshheading:9173910-Humans, pubmed-meshheading:9173910-Immunoenzyme Techniques, pubmed-meshheading:9173910-Male, pubmed-meshheading:9173910-Middle Aged, pubmed-meshheading:9173910-Nerve Tissue Proteins, pubmed-meshheading:9173910-Neurites, pubmed-meshheading:9173910-Neurofibrillary Tangles, pubmed-meshheading:9173910-Peptide Fragments, pubmed-meshheading:9173910-Staining and Labeling, pubmed-meshheading:9173910-Temporal Lobe

Sequence of deposition of heterogeneous amyloid beta-peptides and APO E in Down syndrome: implications for initial events in amyloid plaque formation.

Journal Article, Research Support, U.S. Gov't, P.H.S., Research Support, Non-U.S. Gov't