Amyloid β Levels in Human Red Blood Cells

Amyloid beta-peptide (A beta) is hypothesized to play a key role by oxidatively impairing the capacity of red blood cells (RBCs) to deliver oxygen to the brain. These processes are implicated in the pathogenesis of Alzheimer's disease (AD). Although plasma A beta has been investigated thoroughly, the presence and distribution of A beta in human RBCs are still unclear. In this study, we quantitated A beta 40 and A beta 42 in human RBCs with ELISA assays, and provided evidence that significant amounts of A beta could be detected in RBCs and that the RBC A beta levels increased with aging. The RBC A beta levels increased with aging. On the other hand, providing an antioxidant supplement (astaxanthin, a polar carotenoid) to humans was found to decrease RBC A beta as well as oxidative stress marker levels. These results suggest that plasma A beta 40 and A beta 42 bind to RBCs (possibly with aging), implying a pathogenic role of RBC A beta. Moreover, the data indicate that RBC A beta 40 and A beta 42 may constitute biomarkers of AD. As a preventive strategy, therapeutic application of astaxanthin as an A beta-lowering agent in RBCs could be considered as a possible anti-dementia agent.