Supply oxygen to the brain, RBCs must deform as they pass through the narrow pores of capillaries. However, RBC deformability reportedly decreases when Ab adheres to RBC [32]. Thus, the interaction of Ab with RBC may decrease blood flow, impair oxygen delivery to the brain and contribute to brain hypoxia [32]. These processes are implicated in the pathogenesis of AD. In support of these notions, a relationship between blood (plasma) Ab and AD was observed in Down syndrome patients, among whom those with elevated Ab levels in plasma were reported to have a greater risk of developing AD [33]. Additional research (e.g., measurement of Ab levels in RBCs of AD patients) would be necessary to confirm these hypotheses. On the other hand, as 18334597 a preventive strategy, compounds that are capable of minimizing the accumulation of Ab in blood might be useful therapeutically. In this study, we showed that after astaxanthin supplementation, Ab40 and Ab42 concentrations in RBC (but not plasma) were significantly decreased (Fig. 1, Table 2).Amyloid b Determination in Human ErythrocytesIn addition, inverse relationships between RBC Ab and astaxanthin levels were found (Fig. 2). Our previous in vitro and in vivo murine studies also indicated that carotenoid supplementation, especially astaxanthin, could attenuate Ab-induced MedChemExpress 4EGI-1 oxidative stress in RBCs [9]. It is therefore likely that carotenoids (astaxanthin) act as antioxidants and/or reduce 1313429 the binding of Ab to RBCs, thereby improving the resistance of RBCs to Ab-induced oxidative damage. For other carotenoid, b-carotene reportedly inhibited fibrillation and oligomerization of Ab [34,35], indicating a possibility that carotenoid moieties may bind to C-terminal portion of Ab, thereby inhibiting the binding of Ab to RBC. On the other hand, for currently unknown reasons, astaxanthin changed the levels of Ab in RBC but not in plasma. This may be related to Ab clearance from plasma, since order Calciferol excessive plasma Ab is reportedly cleared from the circulation by mainly hepatic Ab uptake through the interactions with liver low-density lipoprotein receptor-related protein (LRP-1) [36?8]. Further studies are needed to evaluate the effectiveness and mechanisms by which carotenoid (astaxanthin) could be beneficial for the treatment of dementia. Studies have reported that Ab elicits neurotoxic activity via generation of reactive oxygen species (ROS) [39]. The mechanism by which Ab generates ROS is not fully understood, although one study implicates involvement of the methionine residue at position 35 of Ab [40]. If, indeed, Ab induces ROS, it could in turn trigger membrane oxidative injury in RBCs. Because Ab seems to cause RBC aggregation and hemolysis [9], it is plausible that Abinduced hemolysis enhances a cascade of oxidative reactions inRBC. These reactions produce superoxide, which dismutates to form hydrogen peroxide. These ROS cause formation and accumulation of RBC PLOOH, and this could increase membrane rigidity and decrease the deformability of RBCs. In concordance with these considerations, positive correlations between RBC Ab and PLOOH were found in the present study (Fig. 3). In conclusion, we provided evidence that Ab40 and Ab42 concentrations were much higher in RBCs than in plasma and that RBC Ab levels increased with aging. We also found that after astaxanthin supplementation, there was a decrease in RBC Ab concentrations. The RBC Ab levels were positively correlated with RBC PLOOH, and inversely correlated w.Supply oxygen to the brain, RBCs must deform as they pass through the narrow pores of capillaries. However, RBC deformability reportedly decreases when Ab adheres to RBC [32]. Thus, the interaction of Ab with RBC may decrease blood flow, impair oxygen delivery to the brain and contribute to brain hypoxia [32]. These processes are implicated in the pathogenesis of AD. In support of these notions, a relationship between blood (plasma) Ab and AD was observed in Down syndrome patients, among whom those with elevated Ab levels in plasma were reported to have a greater risk of developing AD [33]. Additional research (e.g., measurement of Ab levels in RBCs of AD patients) would be necessary to confirm these hypotheses. On the other hand, as 18334597 a preventive strategy, compounds that are capable of minimizing the accumulation of Ab in blood might be useful therapeutically. In this study, we showed that after astaxanthin supplementation, Ab40 and Ab42 concentrations in RBC (but not plasma) were significantly decreased (Fig. 1, Table 2).Amyloid b Determination in Human ErythrocytesIn addition, inverse relationships between RBC Ab and astaxanthin levels were found (Fig. 2). Our previous in vitro and in vivo murine studies also indicated that carotenoid supplementation, especially astaxanthin, could attenuate Ab-induced oxidative stress in RBCs [9]. It is therefore likely that carotenoids (astaxanthin) act as antioxidants and/or reduce 1313429 the binding of Ab to RBCs, thereby improving the resistance of RBCs to Ab-induced oxidative damage. For other carotenoid, b-carotene reportedly inhibited fibrillation and oligomerization of Ab [34,35], indicating a possibility that carotenoid moieties may bind to C-terminal portion of Ab, thereby inhibiting the binding of Ab to RBC. On the other hand, for currently unknown reasons, astaxanthin changed the levels of Ab in RBC but not in plasma. This may be related to Ab clearance from plasma, since excessive plasma Ab is reportedly cleared from the circulation by mainly hepatic Ab uptake through the interactions with liver low-density lipoprotein receptor-related protein (LRP-1) [36?8]. Further studies are needed to evaluate the effectiveness and mechanisms by which carotenoid (astaxanthin) could be beneficial for the treatment of dementia. Studies have reported that Ab elicits neurotoxic activity via generation of reactive oxygen species (ROS) [39]. The mechanism by which Ab generates ROS is not fully understood, although one study implicates involvement of the methionine residue at position 35 of Ab [40]. If, indeed, Ab induces ROS, it could in turn trigger membrane oxidative injury in RBCs. Because Ab seems to cause RBC aggregation and hemolysis [9], it is plausible that Abinduced hemolysis enhances a cascade of oxidative reactions inRBC. These reactions produce superoxide, which dismutates to form hydrogen peroxide. These ROS cause formation and accumulation of RBC PLOOH, and this could increase membrane rigidity and decrease the deformability of RBCs. In concordance with these considerations, positive correlations between RBC Ab and PLOOH were found in the present study (Fig. 3). In conclusion, we provided evidence that Ab40 and Ab42 concentrations were much higher in RBCs than in plasma and that RBC Ab levels increased with aging. We also found that after astaxanthin supplementation, there was a decrease in RBC Ab concentrations. The RBC Ab levels were positively correlated with RBC PLOOH, and inversely correlated w.
