Circulating microRNAs as Promising Biomarkers in Parkinson's Disease

Our study aims to examine possible Parkinson Disease (PD)-related circulating microRNAs (miRNA) and their potential roles and use cases in screening, diagnosis, and the disease progress in Turkish population. For this purpose, we selected 7 promising candidates namely miR-16-1, miR-24-3p, miR-30a, miR-30e, miR-34a, miR-34b, miR-331 from multiple studies and bioinformatic web tools. For our study, 51 PD patients with no other severe disease except for hypertension and 20 healthy matching controls were included. Serum samples were collected from venous blood and stored properly. RNA extraction, reverse transcription and real-time polymerase chain reaction (qPCR) for each pre-determined miRNA were applied to all samples with a strong normalization method to determine expression levels. Additionally, validated miR-24-3p target genes were intersected against publicly available CSF proteomics (PXD011216), PBMC transcriptomics (GSE22491), and serum metabolomics (MTBLS10958) datasets. miR-24-3p expression was also examined in two independent miRNA datasets (GSE269775; GSE16658). Statistical analyses were done using SPSS and Qiagen GeneGlobe webtools. Between PD and the control group, miR-24-3p serum levels were found increased 1.7 times (p = 0.0001). Among patients, miR-331 serum levels changed significantly with UPDRS scores (p = 0.027). Multi-omics analysis identified 21 differentially abundant miR-24-3p target proteins in PD CSF (81% downregulated), three cross-platform concordant targets, and five metabolically linked pathways. miR-24-3p levels may differ in different biological compartments in PD. In serum, miR-24-3p may provide significant value as a diagnostic biomarker with 80.4% sensitivity and 85% specificity. miR-331 might be a candidate for predicting the severity of the disease.