Adipokines, Vitamin D, and Selected Inflammatory Biomarkers among Parkinson's Disease Patients with and without Dyskinesia: A Preliminary Examination

Abstract

Parkinson's disease (PD), a widely recognized neurodegenerative disorder, is characterized by a spectrum of symptoms including motor fluctuations and dyskinesia. Neuroinflammation and dysregulation of adipokines are increasingly implicated in the progression of PD. This preliminary study investigated the levels of inflammatory biomarkers and adipokines, namely interleukin-6 (IL-6), tumor necrosis factor α (TNF-α), C-reactive protein (CRP), visfatin, progranulin, and 25(OH)-vitamin D in 52 PD patients, divided equally between those with and without dyskinesia and 26 healthy controls. Significant differences in the levels of IL-6, TNF-α, visfatin, and progranulin were noted between the groups. Patients with dyskinesia exhibited notably higher IL-6 levels compared to controls, and TNF-α was significantly elevated in both PD patient groups relative to the control group. Additionally, visfatin levels were higher in PD patients without dyskinesia as opposed to those with dyskinesia, and progranulin levels were elevated in the non-dyskinetic PD group compared to controls. The findings highlight the potential role of the examined biomarkers in the pathophysiology of PD. Changes in levels of the tested inflammatory biomarkers and adipokines might be associated with Parkinson's disease and its symptoms such as dyskinesia.

Keywords: Parkinson’s disease; adipokines; dyskinesia; inflammation; neurodegeneration; neuroinflammation; vitamin D.

Figure 1

Boxplots for biomarkers that demonstrated statistically significant differences in post hoc analysis. These boxplots include data from two groups of PD patients, as well as the control group. This visual representation provides a clear comparison of the biomarker levels, highlighting the biochemical variances associated with PD. (A): boxplot for concentration of interleukin-6 (IL-6); (B): boxplot for concentration of tumor necrosis factor α (TNF-α); (C): boxplot for concentration of visfatin; (D): boxplot for concentration of progranulin.

Figure 2

Spearman’s correlation diagrams for different groups of Parkinson’s disease patients. Diagram (A) focuses on the group without dyskinesia, while diagram (B) pertains to the group with dyskinesia. Abbreviations used: APTT: activated partial thromboplastin time; CRP: C-reactive protein; IL-6: interleukin-6; INR: international normalized ratio; TNF-α: tumor necrosis factor α.

Figure 3

Putative relationship between inflammation and Parkinson’s disease. Decline in anti-inflammatory agents, both internally produced and externally derived, is expressed by reduced secretion of visfatin and progranulin by adipocytes, alongside a tentative association with vitamin D status. Conversely, there is an escalation in proinflammatory agents that activate microglia, which could be related to periphery inflammation with increased levels of tumor necrosis factor α (TNF-α) and interleukin-6 (IL-6) in the blood plasma. These changes can be connected with the pathogenesis of Parkinson’s disease.