Imbalance of Th17 and T-regulatory cells in peripheral blood and synovial fluid in treatment naive children with juvenile idiopathic arthritis

Objectives: The imbalance between Th17 and T regulatory cells (Tregs) may be a key event in development of autoimmunity. The problem is poorly explored in juvenile idiopathic arthritis (JIA) so far. In this study, peripheral blood (PB) and synovial fluid (SF) Tregs and Th17 cells from were assessed in untreated JIA children. Material and methods: In 50 children with JIA the PB or SF percentages of Tregs and Th17 cells were assessed by flow cytometry, in comparison with PB Tregs and Th17 cells from 28 healthy controls. Additionally, in both groups the levels of proinfammatory cytokines, such as interleukin (IL)-1 beta, IL-6, IL-17, IL-21, IL-23 and tumor necrosis factor alpha (TNF-alpha) were assessed using ELISA method. Results: The proportion of JIA PB Th17 cells was significantly higher than in the controls (p=0.01). Serum levels of IL-1 beta, IL-6, IL-17, IL-23 were also significantly higher in JIA (p=0.011, p=0.007, p=0.008 and p=0.023, respectively). The highest serum IL-6 levels were observed in oligoarthritis JIA (p=0.031). Synovial fluid IL-21 concentration was distinctly higher in polyarticular JIA. Synovial fluid levels of TNF-a, IL-1 beta and IL-6 were significantly higher than in JIA PB (p=0.038, p=0.013 and p<0.001, respectively). There was a significant correlation between IL-6 and PB Tregs (p=0.02). Conclusions: The results of this comprehensive analysis indicate a role of Th17 cell activation in the pathogenesis of JIA.