Characterization And Comprehensive Proteomics Analysis Of Serum Exosomes Derived From Parkinson’s Patients

Objective:Due to the lack of specific methods for early diagnosis of Parkinson’s disease(PD),the present study intends to describe the protein spectrum changes in serum exosomes of PD patients.The i TRAQ-based quantitative proteomic analysis and bioinformatic methods were conducted to identify differentially expressed proteins in PD and their biological function.Methods:Exosomes were isolated via a series of differential centrifugation from serum samples of PD patients and healthy controls,then were validated through transmission electron microscope(TEM)image and nanoparticle tracking analysis(NTA).Western blot assay(WB)was resorted to detect exosome marker proteins including differentiation protein 9(CD9)and tumor susceptibility gene 101 protein(TSG101).Differentially expressed proteins(DEPs)in serum exosomes were further identified through i TRAQ-LC-MS/MS.Gene Ontology(GO)and Kyoto Encyclopedia of Genes and Genomes(KEGG)Pathways databases were implemented to explore the potential mechanism.Protein-protein interaction(PPI)networks were established through STRING database for mining related proteins.Results:×Serum exosomes were successfully isolated from PD patients and healthy people.A total of 41 DEPs(24 up-regulated;18 down-regulated)were identified.KEGG enrichment analysis showed that these DEPs were mainly enriched in some disease-related pathways or were associated with hematopoietic function.GO-biological process analysis showed that most DEPs were involved in the regulation of immune system process,vesicle-mediated transport,response to stress and signal transduction.Furthermore,PPI network revealed some crucial proteins related the pathology of PD.Western blot and ELISA assays further validated the credibility of proteomic results,which include the high expression of SERPINA3 and HPX,as well as the low expression of PLTP.Conclusion:Our study described a differential expression of peripheral serum exosome proteins between PD patients and healthy people.Bioinformatic analysis suggest that these proteins are related to immunoregulation and signal transduction.Certain identified proteins can be potential markers for early diagnosis of PD and molecular diagnosis.