Background: Parkinson's disease (PD) has been linked to T helper 17 (Th17) cells in prior investigations, but the evidence remains inconclusive. To gain a deeper understanding of this potential connection, we conducted a systematic review and meta-analysis.
Methods: A comprehensive search for relevant studies published up to July 8, 2023, was performed across PubMed, EMBASE, and Cochrane Library databases. A random-effect model was employed to synthesize effect sizes and their corresponding 95 % confidence intervals (CIs). Leave-one-out sensitivity analysis and funnel plots with trim-and-fill were utilized to assess the combined results' robustness.
Results: Thirteen studies were ultimately included in the meta-analysis. Pooled effect sizes indicated a significantly higher percentage of Th17 cells in PD patients (Standardized Mean Difference [SMD] = 1.00, 95 % CI 0.30-1.71). Notably, Th17 cell levels were more elevated in Asian PD patients (SMD = 1.33, 95 % CI 0.31-2.35). Additionally, the percentage of Th17 cells positively correlated with Movement Disorder Society Unified Parkinson's Disease Rating Scale-III (UPDRS-III) scores (r = 0.22, 95 % CI 0.01-0.41), indicating a link to motor dysfunction. Conversely, a negative correlation was observed with Cognitive function scale scores (r = - 0.27, 95 % CI -0.47--0.04), suggesting a potential association with cognitive decline.
Conclusions: This study revealed a positive association between Th17 cells and PD, with PD patients exhibiting elevated Th17 levels. Furthermore, the percentage of Th17 cells correlated with motor and cognitive impairments in PD patients.
Keywords: Meta-analysis; Neuroinflammation; Parkinson's disease; Systematic review; Th17 cells.
Copyright © 2024. Published by Elsevier B.V.