Levels of oligomeric α-Synuclein in reflex tears distinguish Parkinson's disease patients from healthy controls

Abstract

Aim: Due to active engagement of sensory and afferent nerve fibers in reflex tearing which could be affected in Parkinson's disease (PD), we tested reflex tears as a source of potential PD biomarkers. Patients & methods: Reflex tears collected from 84 PD and 84 age- and sex-equivalent healthy controls (HC) were used to measure levels of oligomeric α-Syn (α-Syn_Oligo), total α-Syn (α-Syn_Total), CCL2, DJ-1, lactoferrin and MMP9. Results: α-syn_Oligo (p < 0.0001), CCL2 (p = 0.003) and lactoferrin (p = 0.002) were significantly elevated in PD patient tears relative to HC tears. Tear flow was significantly lower in PD relative to HC (p = 0.001). Conclusion: Reflex tears are a potential source for detection of characteristic changes in PD patients.

Trial registration: ClinicalTrials.gov NCT03037463.

Keywords: Parkinson's disease; biomarker; diagnosis; oligomeric α-Synuclein; tears; α-Synuclein.