The aim of this study was to characterize peripheral inflammatory markers in patients with early Parkinson's disease (PD) and to explore whether these markers contribute to motor and non-motor symptoms. We collected serum from patients with early PD (n = 58) and from healthy control subjects (n = 20). The following inflammatory markers were measured: interleukin (IL)-1β, IL-2, IL-6, IL-10, tumor necrosis factor-α, and high-sensitivity C-reactive protein. The Movement Disorders Society Unified Parkinson's Disease Rating Scale part 3 and Hoehn and Yahr stage were used to assess motor symptoms, and the Non-motor Symptoms Scale, the Cross-Cultural Smell Identification Test, the Montreal Cognitive Assessment, and the Composite Autonomic Symptom Score 31 (COMPASS-31) were used to assess non-motor symptoms. The levels of IL-1β, IL-2, and IL-6 were higher in the PD group than in the control group. However, only IL-1β among those markers remained significant after Bonferroni correction (P = 0.024). In the PD group, the anti-inflammatory cytokine IL-10 levels correlated positively with the COMPASS-31 score (r = 0.277, P = 0.035), whereas no correlation was found between the other inflammatory marker levels and motor or non-motor symptoms. Among the domains of the COMPASS-31, the IL-10 levels correlated only with the gastrointestinal domain (r = 0.358, P = 0.006). Our results suggest increased peripheral inflammation in the early stage of PD, but the role of inflammation in motor and non-motor symptoms is unclear. Although we found a correlation between IL-10 levels and gastrointestinal symptoms, this finding may simply reflect a protective response against inflammatory processes associated with the disease.
Keywords: Immune markers; Inflammation; Interleukin; Non-motor symptoms; Parkinson’s disease.
Copyright © 2018 Elsevier Ltd. All rights reserved.