Isoform-specific vasoconstriction induced by Apolipoprotein E and modulation of this effect by Alzheimer's β-amyloid peptide

Abstract

A β peptides are thought to be centrally involved in Alzheimer's disease (AD) pathogenesis, although A β's pathophysiological mechanisms remain to be elucidated. We previously showed that soluble β-amyloid 1–40 (A β) and A β 1–42 exhibit vasoactive properties, and are able to promote vasoconstriction in rat aortae induced by an endogenous vasoconstrictor, endothelin-1. It is well established that the APOE ϵ4 allele confers risk for both familial and sporadic AD, as well as for hypertension. We now report that physiologic amounts (10 nM) of specific human recombinant apoE isoforms are vasoactive (E4>E3, and not E2) in isolated rat aortae. In order to investigate if various apoE isoforms could modulate A β vasoactivity, we co-incubated A β 1–40 with various isoforms of apoE in our tissue bath system. Our results show that, while none of the apoE isoforms are able to affect the maximum constriction induced by A β; the APOE E4 isoform synergistically enhances the rate of vasoconstriction induced by A β. Our data suggest that apoE may promote hypertension and contribute to AD pathogenesis via enhancement of vasoconstriction, and support a link between hypertension, cerebral amyloid angiopathy and AD.