A NESTED CASE-CONTROL STUDY OF PLASMA-BASED EXTRACELLULAR VESICLES BIOMARKERS OF ALZHEIMER’S DISEASE

Objective: This project will screen and validate peripheral blood extracellular vesicles (EVs) biomarkers for Alzheimer’s disease (AD), which has important clinical significance for the treatment of AD.Design and method: We retrospectively identified 2 diagnostic groups of 50 individuals, 25 AD and 25 were healthy controls. Plasma neuron-derived extracellular vesicles (NDEVs) were isolated, characterization and high throughput analysis were conducted. LC-MS/MS analysis was performed using timsTOF Pro mass spectrometry (Bruker) coupled with Nanoelute (Bruker). ROC curve analysis was used to determine the performance of the EVs biomarkers and diagnosis models. In the screening of significantly different proteins, the expression change (FC)> 2.0 times (up-regulated greater than 2.0 times or down-regulated less than 0.5 times) and P value<0.05 (T-test) were used as criteria to obtain the up-regulated and down-regulated EVs proteins between comparison groups. Results: In this study, 8 biomarkers were detected, namely, Q08830 (FGL1), A0A024R7F1 (PRKCSH), P48426 (PIP4K2A). A8K2W3 (FLJ78516), Q14644 (RASA3), Q9Y2A7 (NCKAP1), Q5JTA5 (CD34), 5 proteins of CD34 and Q15389 (ANGPT1). Among them, FGL1, PRKCSH and PIP4K2A are up-regulated EVs biomarkers, and the other 5 are down-regulated ones. ROC curve analysis was used to determine the performance of ev biomarkers, and area under the curve (AUC) was calculated to determine the utility of each marker. The analysis results showed that there were certain differences in the expression levels of the 8 biomarkers under different conditions, all of these biomarkers had AUC >0.75. Conclusions: Our study develops a method that includes EVs protein biomarkers that can be used to distinguish AD from control candidates, thus providing an additional method that can be used to complement classical diagnostic methods. It is hoped that these results will contribute to further understanding of the applicability of serum-based low-cost, less invasive diagnostic methods.