Lewy Body-Associated Proteins A-Synuclein (a-syn) as a Plasma-Based Biomarker for Parkinson’s Disease

INTRODUCTION: To explore the combined diagnostic value of plasma Lewy body-associated proteins (p-Asyn at ser129, total α-syn, and oligomeric α-syn) for the diagnosis of PD versus healthy controls (HCs) and other PD syndromes (PDs), as well as clinical characteristics prediction. METHODS: This study included 145 participants: 79 patients with PD, 24 patients with PDs, and 42 HCs. A panel of plasma levels of p-Asyn, total α-syn, and oligomeric α-syn was measured by enzyme-linked immunosorbent assay (ELISA). The primary outcome was the discriminative accuracy of the combined three plasma biomarkers for PD. RESULTS: The mean age was 65.43 (SD, 7.467) in the control group, 64.49 (SD, 8.224) in participants with PD, and 69.25 (SD, 7.952) in PDs. The plasma Lewy body-associated protein levels were significantly higher in patients with PD than in age-matched HCs, However, there was no difference in patients with PD and PDs. Of note, a combination of plasma p-Asyn, total α-syn, and oligomeric α-syn was a better biomarker for discriminating PD from HCs, with an AUC of 0.8552 (p < 0.0001, 95%CI, 0.7635–0.9409), which was significantly higher than plasma p-Asyn (ΔAUC, 0.1797), total α-syn (ΔAUC, 0.0891) and oligomeric α-syn (ΔAUC, 0.1592) alone. Meanwhile, Lewy body-associated proteins had no connections between different motor stages and dementia performances. CONCLUSION: Our results suggested that plasma Lewy body-associated proteins, may serve as a non-invasive biomarker to aid the diagnosis of PD from HCs. In addition, increased plasma Lewy body-associated proteins were not associated with the progression of motor and non-motor symptoms.