Fleecy amyloid deposits in the internal layers of the human entorhinal cortex are comprised of N-terminal truncated fragments of Abeta.
The deposition of amyloid in the brain is a hallmark of Alzheimer disease (AD). Amyloid deposits consist of accumulations of beta-amyloid (Abeta), which is a 39-43 amino-acid peptide cleaved from the Abeta-protein precursor (APP). Another cleavage product of APP is the P3-peptide, which consists of the amino acids 17-42 of the Abeta-peptide. In order to study the deposition of N-terminal truncated forms of Abeta in the human entorhinal cortex, serial sections from 16 autopsy cases with AD-related pathology were immunostained with antibodies against Abeta1-40, Abeta1-42, Abeta17-23, and Abeta8-17, as well as with the Campbell-Switzer silver impregnation for amyloid. In the external entorhinal layers (pre-beta and pre-gamma), sharply delineated diffuse plaques were seen. They were labeled by silver impregnation and by all Abeta-antibodies used. By comparison, in the internal layers (pri-alpha, pri-beta, and pri-gamma) blurred, ill-defined clouds of amyloid existed, in addition to sharply delineated diffuse plaques. These clouds of amyloid were termed "fleecy amyloid." Immunohistochemically, fleecy amyloid was stained by Abeta17-23 and Abeta1-42 antibodies, but not with antibodies against Abeta8-17 and Abeta1-40. Using the Campbell-Switzer technique, the fleecy amyloid deposits were found to be fine argyrophilic amyloid fibrils. Thus, the internal entorhinal layers are susceptible to a distinct type of amyloid, namely fleecy amyloid. This fleecy amyloid obviously corresponds to N-terminal truncated fragments of Abeta1-42, probably representing the P3-peptide. These N-terminal truncated fragments of Abeta are capable of creating fine fibrillar "amyloid."
Department of Morphology, J.W. Goethe University of Frankfurt, Germany.
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D000368:Aged; D000369:Aged, 80 and over; D016229:Amyloid beta-Peptides / Q000032:analysis*; D000686:Amyloidosis / Q000473:pathology*; D004396:Coloring Agents; D018728:Entorhinal Cortex / Q000737:chemistry* / Q000473:pathology*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D016874:Neurofibrillary Tangles / Q000737:chemistry / Q000473:pathology; D010446:Peptide Fragments / Q000032:analysis*; D016622:Silver Staining; D013194:Staining and Labeling / Q000379:methods
D016229:Amyloid beta-Peptides; D004396:Coloring Agents; D010446:Peptide Fragments; C078592:amyloid beta-protein (1-40); C075222:amyloid beta-protein (1-42); C100690:amyloid beta-protein p3, human; C086839:amyloid beta-protein (17-42)