DAT and TH expression marks human Parkinson's disease in peripheral immune cells

Area of Science:

• Neuroscience
• Immunology
• Biochemistry

Background:

• Parkinson's disease (PD) involves dopamine neuron loss and altered dopamine transporter (DAT) and tyrosine hydroxylase (TH) expression.
• Current diagnostic methods for PD are limited, especially for early detection and monitoring treatment effectiveness.
• PD pathology impacts both the central nervous and peripheral immune systems.

Purpose of the Study:

• To investigate the expression of DAT and TH in peripheral immune cells as potential biomarkers for Parkinson's disease.
• To explore the association between dopaminergic markers on immune cells and PD pathophysiology.
• To determine if these markers can differentiate PD patients from healthy controls and those with Alzheimer's disease.

Main Methods:

• Immunophenotyping of blood samples from drug-naive PD patients and healthy controls to identify myeloid-derived suppressor cells (MDSCs).
• Quantification of DAT and TH expression on peripheral blood mononuclear cells (PBMCs) using flow cytometry.
• Comparison of DAT+/TH+ PBMC levels in PD patients, healthy subjects, and an Alzheimer's disease cohort.
• Reverse translational studies in animal models to elucidate the mechanistic link between CNS changes and peripheral immune cell alterations.

Main Results:

• Increased levels of DAT+/TH+ monocytic myeloid-derived suppressor cells (MDSCs) were observed in PD patients.
• Drug-naive PD patients showed significantly higher percentages of DAT+/TH+ PBMCs compared to healthy controls, irrespective of disease duration or severity.
• PD treatment negatively modulated DAT+/TH+ expressing PBMCs.
• No alterations in DAT+/TH+ PBMCs were found in the Alzheimer's disease cohort, suggesting specificity to PD.

Conclusions:

• The dopaminergic machinery, specifically DAT and TH expression, on peripheral immune cells is associated with human Parkinson's disease.
• Elevated DAT+/TH+ PBMCs represent a potential diagnostic biomarker for PD.
• These findings offer new avenues for investigating PD pathophysiology and developing diagnostic tools.