α-Synuclein in salivary extracellular vesicles as a potential biomarker of Parkinson's disease

Zhentang Cao; Yufeng Wu; Genliang Liu; Ying Jiang; Xuemei Wang; Zhan Wang; Tao Feng

doi:10.1016/j.neulet.2018.12.030

α-Synuclein in salivary extracellular vesicles as a potential biomarker of Parkinson's disease

Neurosci Lett. 2019 Mar 23:696:114-120. doi: 10.1016/j.neulet.2018.12.030. Epub 2018 Dec 21.

Authors

Zhentang Cao¹, Yufeng Wu², Genliang Liu¹, Ying Jiang¹, Xuemei Wang¹, Zhan Wang¹, Tao Feng³

Affiliations

¹ Center for Neurodegenerative Disease, Department of Neurology, Beijing Tiantan Hospital, Capital Medical University, Beijing, China; China National Clinical Research Center for Neurological Diseases, Beijing, China.
² Clinical Laboratory, Peking University Third Hospital, Peking University, Beijing, China; Department of Pathology, Peking University School of Basic Medical Sciences, Peking University, Beijing, China; Beijing Key Laboratory of Research and Transformation on Neurodegenerative Diseases Biomarkers, Beijing, China.
³ Center for Neurodegenerative Disease, Department of Neurology, Beijing Tiantan Hospital, Capital Medical University, Beijing, China; China National Clinical Research Center for Neurological Diseases, Beijing, China; Parkinson's Disease Center, Beijing Institute for Brain Disorders, Capital Medical University, Beijing, China. Electronic address: bxbkyjs@sina.com.

PMID: 30579996
DOI: 10.1016/j.neulet.2018.12.030

Abstract

Background: Detection of α-synuclein (α-syn) in biological fluids such as saliva may serve as potential biomarker of PD. α-syn pertaining to extracellular vesicles (EVs) has been recently studied in plasma, but not in other biological fluids such as saliva.

Aim: 1) To investigate the presence of exosomes in PD saliva; 2) to explore the value of α-syn in salivary EVs as potential biomarker in PD.

Methods: Saliva samples were obtained from 74 PD and 60 healthy controls (HCs). The EVs were extracted from saliva by XYCQ EV Enrichment KIT. Western blot and Nanosight 300 were used to validate the existence of exosomes in EVs and to analyze the size of salivary EVs. Salivary EVs α-syn levels, including total α-syn (α-syn_Total), oligomeric α-syn (α-syn_Olig) and phosphorylated-ser129 α-syn (α-syn_PS129), were measured by Electrochemiluminescence (ECL) assays. Diagnostic value and clinical relevance of salivary EVs α-syn were assessed by Receiver Operator Characteristic (ROC) curve and Spearman correlation.

Results: Alix and CD9 positive EVs, representing the presence of exosomes, was detected in PD salivary samples. Size of salivary EVs was about 30-400 nm. The levels of α-syn_Olig and α-syn_Olig/α-syn_Total in the salivary EVs were higher in PD than in HCs (10.39 ± 1.46 pg/ng vs.1.37 ± 0.24 pg/ng, p＜0.001;1.70 ± 0.52 pg/ng vs.0.67 ± 0.26 pg/ng, p＜0.001). There was no significant difference in α-syn_Total、α-syn_PS129、 α-syn_PS129/α-syn_Total ratio between PD and HCs (P = 0.723, 0.634, 0.734, respectively). α-syn_Olig 2.05 pg/ng distinguished PD from HCs with sensitivity 92% and specificity 86%; α-syn_Olig /α-syn_Total 0.18 pg/ng differentiated PD from HCs with sensitivity 81% and specificity 71%. No significant correlation between salivary EVs α-syn_Olig, α-syn_Olig/α-syn_Total and disease severity was found.

Conclusions: Exosomes are present in PD saliva. The α-syn_Olig and α-syn_Olig/α-syn_Total ratio in salivary EVs may serve as potential diagnostic biomarkers for PD.

Keywords: Biomarker; Extracellular vesicles; Oligomeric α-synuclein; Parkinson's disease; Saliva.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Biomarkers / blood
Exosomes / metabolism*
Extracellular Vesicles / metabolism
Humans
Parkinson Disease / metabolism*
ROC Curve
Saliva / metabolism*
alpha-Synuclein / metabolism*

Substances

Biomarkers
alpha-Synuclein