An inclusive study on cytokine gene expression in Parkinson's disease: Advanced analysis using Bayesian regression...

Parkinson's disease (PD) is the second most prevalent neurodegenerative disease throughout the globe whose specific pathophysiology is unknown. Researchers believe that inflammation and oxidative stress contribute to PD development. Also, alterations in cytokines production appear to have a key role in the pathogenesis of PD. The aim of the current study was to evaluate gene expression levels of nine cytokines in the peripheral blood of PD patients compared to a healthy control group.

Real-time PCR was used to analyze cytokines gene expression followed by advanced statistical analysis performed using Bayesian regression model in R (version 4.1.0) statistical software.

TNF-α, IL-1β, IL-2, IL-4, IFN-γ, IL-17 and IL-6 transcript levels were upregulated in patients compared to healthy controls. However, CXCL8 expression was downregulated in patients compared to controls and IFN-β expression was not statistically different between the two groups. While we found no significant difference between the groups based on gender and age regarding TNF-α, IL-1β, CXCL8, IL-2, IL-4, IFN-γ and IFN-β gene expression, IL-6 and IL-17 transcript levels showed significant upregulations in older subjects and in females, respectively. In addition, we found that the interaction effects between gender and group on gene expression levels were not significant. In this way, the subgroup analysis within gender revealed that in each gender, expression levels of TNF-α, IL-2, IL-4, IL-6, IFN-γ and IL-17 were significantly higher in patients than controls. However, IFN-β expression level did not show any significant difference between groups and subgroups.

The present study provides evidence on significant alterations in cytokine expression with different patterns and points to immune system dysregulation in PD.