Blood-based test for disease progression and early diagnosis of Parkinson’s disease (PD) is a long awaited but unsolved key problem in the clinic. The profiles of microRNAs (miRNAs) are regarded as potential diagnostic biomarkers in human diseases whereas the miRNAs in the periphery are susceptible to the influence of various components. MiRNAs enriched in serum exosomes have revealed disease-specific advantages for the diagnosis due to their high abundance, stability and resistant to degradation. This study aimed to screen differentially expressed exosomal miRNAs between healthy controls and PD patients to aid in diagnosis.
A total of 103 healthy controls and diagnosed PD patients at different Hoehn and Yahr (H&Y) stages in Tangdu Hospital were included. In total, 185 differentially expressed miRNAs were obtained through miRNA sequencing of serum exosomes as well as edgeR and t-test analyses. Subsequently, the weighted gene co-expression network analysis (WGCNA) was utilized to identify the commonly expressed miRNAs in all stages of PD by constructing connections between modules and specifically expressed miRNAs in each stage of PD by functional enrichment analysis. The obtained miRNAs were further validated by quantitative real-time polymerase chain reaction (qRT-PCR) with peripheral blood exosomes from 30 more participants.
Using WGCNA, it was found that 4 miRNAs were commonly associated with all the stages of PD and 13 miRNAs were specifically associated with different stages of PD. Among the 17 miRNAs, 2 were commonly expressed in all the stages of PD and 5 were specifically expressed in different stages of PD via qRT-PCR; 5 were also specifically expressed in different stages of PD by WGCNA, but validation by qRT-PCR showed inconsistent results; the remaining 5 miRNAs did not exhibit significant differences by qRT-PCR.
This study revealed that the 7 serum exosomal miRNAs (hsa-miR-374a-5p, hsa-miR-374b-5p, hsa-miR-199a-3p, hsa-miR-195-5p, hsa-miR-28-5p, hsa-miR-22-5p and hsa-miR-151a-5p) we screened out may potentially be used as biomarkers for progression and early grading diagnosis of PD in the population.