Anomalies in peripheral adaptive immune cells can promote the development and progression of Parkinson’s disease (PD) via increased immune cell infiltration and neuroinflammation in the central nervous system, according to study results published in Neurology: Neuroimmunology & Neuroinflammation.
While adaptive immunity has been found to play a role in the pathogenesis of Parkinson’s disease, there is currently a lack of clear understanding of the role of T and B cells, particularly the cytokines produced by these cells, in the disease.
To improve this understanding, the study researchers evaluated peripheral blood samples from patients with early-stage Parkinson’s disease (n = 41) and healthy controls (n = 45). They used flow cytometry to analyze peripheral blood mononuclear cells for surface markers and intracellular cytokine production. In addition, the study researchers analyzed relationships between clinical parameters and immunological changes.
They stained peripheral blood samples with CD45, CD3, CD4, CD8, CCR7 and CD45RA. The results showed a significant decrease in CCR7 + CD45RA + -naive CD4 + T cells and a significant increase in CCR7 + CD45RA− CD4 + T cells of central memory (TCM) in patients with Parkinson’s disease compared to healthy controls.
Patients who had elevated CD4 + TCM cells had a deterioration in their Movement Disorder Society Parkinson’s disease rating scale.
In addition, the study researchers observed a significant increase in interleukin (IL) 17-producing CD4 + Th17 cells, IL-4-producing CD4 + Th2 cells and IFN-γ-producing CD8 + T cells in patients with Parkinson’s disease compared to healthy controls. “Therefore, the increase in IFN-γ-producing cytotoxic CD8 + T cells in patients with Parkinson’s disease can contribute to both neuroinflammation and neuronal damage,” the researchers write.
There was also a decrease in naive B cells, as well as an increase in unswitched memory and doubly negative B cells. Tumor necrosis factor-α-producing CD19 + B cells were also significantly increased in the PD samples.
One limitation of this study was the lack of long-term follow-up. Therefore, the researchers were unable to assess longitudinal immune phenotypes or disease progression in patients with Parkinson’s disease compared to healthy controls.
Based on their findings, the study’s researchers concluded that their results “may shed light on potential immunotherapies that target dysregulated CD4 + T cells, CD8 + T cells, and CD19 + B cells in patients with Parkinson’s disease”.
Yan Z, Yang W, Wei H, et al. Dysregulation of the adaptive immune system in patients with early Parkinson’s disease. Neurol Neuroimmunol Neuroinflamm. 2021; 8 (5): e1036. doi: 10.1212 / NXI.0000000000001036