Oligomeric α-synuclein is increased in basal tears of Parkinson's patients

Aim: Secretion of proteins into basal tears of Parkinson's disease (PD) patients may be altered by changes in nerve function. Materials & methods: Oligomeric alpha-Syn(Oligo) and total alpha-Syn(Total), CCL-2, DJ-1, LF and MMP-9 were measured in basal tears from 93 PD patients and 82 age- and sex-equivalent healthy controls. Results: alpha-Syn(Total) was decreased (p = 0.0043), whereas alpha-Syn(Oligo) (p < 0.0001) and the ratio of alpha-Syn(Oligo)/alpha-Syn(Total) (p < 0.0001) were increased in basal tears from PD patients compared with healthy controls. Area under receiver-operating curves of alpha-Syn(Oligo) and alpha-Syn(Oligo)/alpha-Syn(Total) contents were 0.70 (95% confidence limits: 0.621-0.774) and 0.72 (95% confidence limits: 0.642-0.792). Conclusion: PD patient basal tears may contain biomarkers that can be assayed noninvasively and inexpensively.