The
amyloid-β 43 (Aβ43)
peptide has been shown to be abundantly expressed in
Alzheimer's disease plaques, whereas only relatively low levels have been demonstrated in
cerebral amyloid angiopathy (CAA). To better understand this discrepant distribution, we studied various biochemical properties of Aβ43, in comparison with Aβ40 and Aβ42. We assessed the interaction of Aβ43 with the three
apoE isoforms (
apoE2,
apoE3, and
apoE4) using SDS-PAGE/Western blotting and ELISA, aggregation propensity using
thioflavin T assays, and cytotoxicity towards cerebrovascular cells using MTT assays. We found that Aβ43 did not differ from Aβ42 in its interaction with
apoE, whereas Aβ40 had a significantly lower degree of interaction with
apoE. At a molar ratio of 1:100 (
apoE:Aβ), all
apoE isoforms were comparably capable of inhibiting aggregation of Aβ40 and Aβ42, but not Aβ43. All Aβ variants had a concentration-dependent negative effect on metabolic activity of cerebrovascular cells. However, the degree of this effect differed for the three Aβ
isoforms (Aβ40 > Aβ42 > Aβ43), with Aβ43 being the least cytotoxic
peptide towards cerebrovascular cells. We conclude that Aβ43 has different biochemical characteristics compared with Aβ40 and Aβ42. Aggregation of Aβ43 is not inhibited by
apoE, in contrast to the aggregation of Aβ40 and Aβ42. Furthermore, cerebrovascular cells are less sensitive towards Aβ43, compared with Aβ40 and Aβ42. In contrast, Aβ43 neither differed from Aβ42 in its aggregation propensity (in the absence of
apoE) nor in its
apoE-binding capacity. Altogether, our findings may provide an explanation for the lower levels of Aβ43 accumulation in cerebral vessel walls.