MicroRNA‑34a‑5p expression in the plasma and in its extracellular vesicle fractions in subjects with Parkinson's
Ilaria Grossi1, Annalisa Radeghieri1, Lucia Paolini1
1Department of Molecular and Translational Medicine, University of Brescia, I‑25123 Brescia, Italy.
Abstract:
Parkinson's disease (PD) is an important disabling age‑related disorder and is the second most common neurodegenerative disease. Currently, no established molecular biomarkers exist for the early diagnosis of PD. Circulating microRNAs (miRNAs), either vesicle‑free or encapsulated in extracellular vesicles (EVs), have emerged as potential blood‑based biomarkers also for neurodegenerative diseases. In this exploratory study, we focused on miR‑34a‑5p because of its well‑documented involvement in neurobiology. To explore a differential profile of circulating miR‑34a‑5p in PD, PD patients and age‑matched control subjects were enrolled. Serial ultracentrifugation steps and density gradient were used to separate EV subpopulations from plasma according to their different sedimentation properties (Large, Medium, Small EVs). Characterization of EV types was performed using western blotting and atomic force microscopy (AFM); purity from protein contaminants was checked with the colorimetric nanoplasmonic assay. Circulating miR‑34a‑5p levels were evaluated using qPCR in plasma and in each EV type. miR‑34a‑5p was significantly up‑regulated in small EVs devoid of exogenous protein contaminants (pure SEVs) from PD patients and ROC analysis indicated a good diagnostic performance in discriminating patients from controls (AUC=0.74, P<0.05). Moreover, miR‑34a‑5p levels in pure SEVs were associated with disease duration, Hoehn and Yahr and Beck Depression Inventory scores. These results underline the necessity to examine the miRNA content of each EV subpopulation to identify miRNA candidates with potential diagnostic value and lay the basis for future studies to validate the overexpression of circulating miR‑34a‑5p in PD via the use of pure SEVs.
Insights
Circulating microRNAs (miRNAs) show promise as early biomarkers for Parkinson's disease (PD). This study found miR-34a-5p elevated in pure small extracellular vesicles (SEVs) from PD patients, suggesting diagnostic potential.
Area of Science:
- Neuroscience
- Biochemistry
- Genetics
Background:
- Parkinson's disease (PD) is a common age-related neurodegenerative disorder with no current early molecular diagnostic biomarkers.
- Circulating microRNAs (miRNAs), found freely or within extracellular vesicles (EVs), are emerging as potential blood-based biomarkers for neurodegenerative diseases.
- miR-34a-5p is a microRNA with known involvement in neurobiology, making it a candidate for PD biomarker research.
Purpose of the Study:
- To investigate the differential expression profile of circulating miR-34a-5p in Parkinson's disease (PD) patients compared to age-matched controls.
- To explore the potential of miR-34a-5p within specific extracellular vesicle (EV) subpopulations as a diagnostic biomarker for PD.
- To assess the correlation between miR-34a-5p levels and clinical parameters in PD patients.
Main Methods:
- Plasma samples from PD patients and controls were fractionated into different EV subpopulations (Large, Medium, Small EVs) using serial ultracentrifugation and density gradients.
- EV characterization was performed using western blotting and atomic force microscopy (AFM), with purity assessed by a nanoplasmonic assay.
- Quantitative real-time PCR (qPCR) was employed to measure miR-34a-5p levels in plasma and isolated EV subpopulations.
Main Results:
- miR-34a-5p was significantly upregulated in pure small EVs (SEVs) isolated from PD patients compared to controls.
- Receiver Operating Characteristic (ROC) analysis demonstrated good diagnostic performance for pure SEV miR-34a-5p in distinguishing PD patients (AUC=0.74, P<0.05).
- Elevated miR-34a-5p levels in pure SEVs correlated with disease duration, Hoehn and Yahr scores, and Beck Depression Inventory scores.
Conclusions:
- The study highlights the importance of analyzing miRNA content within specific EV subpopulations for identifying reliable diagnostic biomarkers.
- Overexpression of miR-34a-5p in pure SEVs presents a promising blood-based biomarker candidate for early Parkinson's disease diagnosis.
- Further studies are warranted to validate these findings and explore the clinical utility of pure SEV miR-34a-5p in PD management.
