Objective: To evaluate the effect of dopaminergic agonists (DA) on the activation and functionality of regulatory cells in People living with Parkinson’s Disease (PwP).

Background: Neuroinflammation is recognized as a primary mechanism involved in the pathogenesis of Parkinson’s Disease (PD) [1-5]. 

The immune response in PD is characterized by an increase in proinflammatory populations and a decrease in anti-inflammatory populations. A reduction in Treg cells has been observed in untreated PwP, which return to normal levels compared to healthy subjects after one year of treatment with Pramipexole (PPX), along with an increase in the expression of dopaminergic receptors on immune cells [6-14].

Conversely, PwP exhibits a diminished ability of Treg cells to inhibit proliferation. It remains unknown whether the recovery in Treg cell numbers following treatment is accompanied by the restoration of suppressor functionality [15-22].

Method: An observational, cross-sectional, retrospective study was conducted on PwP and controls (Cn) attending a referral center in Mexico between 2021 and 2024.

Venous blood samples were collected, and peripheral blood mononuclear cells (PBMCs) were isolated. PBMCs were labeled with antibodies to identify regulatory and effector T cells, followed by purification using a sorting cytometer. Treg cells were cultured with varying amounts of effector T cells and subsequently analyzed.

Results: 44 participants were included, consisting of 19 Cn and 25 PwP. Among the PwP, 5 had never received treatment (PPX-) and 20 were on pramipexole treatment (PPX+). Sociodemographic variables and scale scores are grouped in Table 1.

The Kruskal-Wallis test revealed significant differences between groups in Percent Inhibition at different effector Treg/T ratios. Post hoc analysis indicated no statistically significant differences between the PPX- and PPX+ groups. The results are detailed in Table 2 and Graph 1.

Conclusion: DA in PwP appears to influence the number of Treg cells positively. However, additional interventions beyond PPX alone may be necessary to fully restore Treg cell functionality. The effects of DA treatment may be insufficient to reverse the proinflammatory effects of the disease, despite their neuroprotective properties. 

It is essential to recruit a larger number of untreated patients to confirm whether differences exist between treated and untreated patients.

Table 1. Sociodemographic, PD-Related Variables.

Table 2. Proliferation Inhibition %.

Table 2. Proliferation Inhibition %.

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