Plasma levels of exosome‐bound Aβs accurately identify Alzheimer’s disease patients

Abstract Background Blood‐based diagnosis of Alzheimer's disease may be the most efficient, non‐invasive, and cost‐saving method. However, in contrast to CSF, the performance of plasma Aβ42/40 ratio is still arguable in AD diagnosis. Recently, exosome‐based biomarkers have been found that is more reliable biomarker especially in blood‐based AD diagnosis. Here, we assessed the performance of plasma levels of exosome‐bound Aβs. Method We quantified plasma levels of exosome‐bound Aβs with a high‐sensitive ABSOL HS system, which is based on PIFA (Photooxidation‐Induced Fluorescence Amplification) technique to detect very small amount (sub pg/mL) of biomarkers (FIG.1). The ABSOL HS system fully‐automated the entire ELISA steps and PIFA measurement using a disposable strip‐well cartridge and tip within 30 minutes. To assess the feasibility of plasma levels of exosome‐bound Aβs, 61 Alzheimer’s disease patients and 60 normal controls were enrolled in this study. Result AD group had lower level (3.447 ± 2.114 pg/mL) of exosome‐bound Aβs than NC group (10.153 ± 6.616 pg/mL). The plasma levels of exosome‐bound Aβs identified Alzheimer’s disease with an area under the ROC curve (AUC) of 0.9124 at a cutoff of 5.564 pg/mL, which was equivalent to 81.97% of sensitivity and 81.67% of selectivity (FIG 2, FIG 3). Conclusion The plasma levels of exosome‐bound Aβs showed similar tendency with plasma Aβ42/40 ratio, but the diagnosis accuracy is higher with AUC of 0.9124 than the plasma Aβ42/40 ratio (AUC about 0.8). In this study, the plasma levels of exosome‐bound Aβs accurately identified Alzheimer’s disease patients, which means the exosomal Aβs could serve as a more reliable biomarker to diagnosis Alzheimer’s disease.