Objective: To perform a comparative proteomic analysis of WBC and exosomes in samples from PD patients and to compare with healthy controls (HC) using a shotgun label-free proteomic methodology in order to identify possible biomarkers related to the H&Y staging scale of the disease.

Background: Regarding progression, PD can be classified according to the H&Y staging scale where patients are classified as early, middle or advanced according to motor impairment. So far, there is no biomarker in the blood to identify the disease and the diagnosis is exclusive clinical. Regarding the biomarkers identification, proteomics allows the identification of the protein expression profile present in a given biological sample unequivocally, providing valuable information about signaling pathways presents in different groups of patients.

Method: 97 PD patients were classified in early, middle and advanced according to the H&Y and 32 HC that were carefully selected. All blood samples were collected and then processed to obtain their WBC. Exosomes were enrichment from blood plasma using a kit. From these WBC and exosomes, protein extraction and subsequent shotgun proteomic analysis were performed; LC-MS/MS. The results were analyzed by bioinformatics.

Results: A total of 724 and 253 proteins were identified and quantified in WBC and exosome samples, respectively. Among these proteins, unique and differentially expressed proteins were identified and analyzed in the different samples. To find over- and underrepresented characteristics we used up or downregulated proteins together with the exclusively identified in PD patients vs HC. Were found 16 and 19 upregulated and 4 and 22 downregulated proteins in PD patients compared to HC, in exosome and WBC sample, respectively. We identified biological pathways and processes related to alterations mainly involving oxidative stress, and an inflammatory profile that led us to evaluate the pro and anti-oxidant profile of these samples. We observed an increased pro-oxidant profile mainly in the early classification and a reduced antioxidant capacity in the H&Y subgroups when compared to HC.

Conclusion: This work contributes with proteomic data from unpublished exosomes and WBC related to different clinical classifications, bringing a new perspective on the possible identification of prognostic blood biomarker in PD.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/proteomic-profiles-analysis-of-plasma-exosomes-and-wbc-reveals-news-insights-of-pd-patients-classified-into-hy-clinical-stage/