APOE ASSOCIATED WITH LIPID HAS A REDUCED CAPACITY TO INHIBIT BETA-AMYLOID FIBRIL FORMATION

APOLIPOPROTEIN E (apoE) and the beta-amyloid peptide are both found in the senile plaques associated with Alzheimer's disease. Several studi es have recently determined that apoE can prevent beta-amyloid fibril (A beta f) formation in vitro. In vivo, apoE is normally associated wi th a lipid source. We show that both recombinant and purified plasma a poE inhibit A beta f formation in a dose-dependent manner. The three m ajor apoE isoforms were equipotent at inhibiting A beta f formation. A poE associated with either cholesterol-containing liposomes or very lo w density lipoproteins displayed less potent inhibition of A beta f fo rmation than their unlipidated counterparts. These results indicate th at the presence of associated lipids reduce the ability of apoE to inh ibit the formation of A beta f in vitro. (C) 1998 Lippincott Williams & Wilkins.