Albumin protects human red blood cells against Abeta25-35-induced lysis more effectively than ApoE.
Inhibition of the lysis of human red blood cells (RBCs) exposed to amyloid peptide Abeta25-35 is an model for screening natural and synthetic substances potentially protective against amyloid damage. In this system, human serum and a component, namely apolipoprotein E (apoE), completely prevent RBC lysis. This report demonstrates that albumin, another serum component, is 8-fold more protective: a concentration of 12.5 microg/ml protects RBCs against 20 microM-Abeta25-35, and prevents the formation of fibrillar Abeta25-35 aggregates stainable by Congo Red. The biological relevance of these findings is suggested by the following: (1) a large fraction ( approximately 90%) of circulating Abeta1-42 is bound to albumin; (2) albumin immunoreactivity is present in brain amyloid plaques; and (3) incubation of Abeta with albumin rapidly decreases detectable levels of free Abeta suggesting epitope masking. The results add new and important functional consequences to the amyloid-albumin relationship and imply that experimental systems investigating Abeta cytotoxicity should consider the protective interaction of albumin.
Galeazzi
Luciano
L
Laboratorio Analisi Chimico-Cliniche, Microbiologiche e di Diagnostica Molecolare, INRCA (IRCSS) via della Montagnola 81, 60100 Ancona, Italy.
Galeazzi
Roberta
R
Valli
M Beatrice
MB
Corder
Elizabeth H
EH
Giunta
Sergio
S
D000418:Albumins / Q000378:metabolism*; D000544:Alzheimer Disease / Q000378:metabolism*; D000595:Amino Acid Sequence; D016229:Amyloid beta-Peptides / Q000009:adverse effects* / Q000032:analysis; D001057:Apolipoproteins E / Q000378:metabolism*; D004305:Dose-Response Relationship, Drug; D004912:Erythrocytes / Q000378:metabolism*; D006801:Humans; D008969:Molecular Sequence Data; D010446:Peptide Fragments / Q000009:adverse effects* / Q000032:analysis; D058225:Plaque, Amyloid / Q000473:pathology
D000418:Albumins; D016229:Amyloid beta-Peptides; D001057:Apolipoproteins E; D010446:Peptide Fragments; C113041:amyloid beta-protein (35-25)