Purpose:
Th17 cells are believed to play a critical role in the pathogenesis of uveitis and are known to secrete various effector cytokines including IL-17 and IL-22.This study aims to assess serum levels of Th17 cytokines in patients with uveitis and evaluate associations between cytokine levels and disease characteristics.
Methods:
One hundred and thirty five serum samples from 89 patients with various forms of uveitis are analyzed using enzyme-linked immunosorbent assay (ELISA) (R&D Systems, Inc). Medical records of these patients are reviewed for demographic data, anatomical and etiologic classification of uveitis, inflammatory activity according standardization of uveitis nomenclature (SUN) working group criteria and immunomodulatory therapy.
Results:
Mean serum IL-17 levels were higher among patients with active uveitis compared to those with quiet disease [109.9 pg/ml vs 77.64 pg/ml; p=0.03], IL-22 levels were comparable between patients with active and quiet uveitis [297.5 pg/ml (95%CI: 130.3-464.6) vs 307.4 pg/ml (95% CI: 186.4-428.3)]. Serum IL-17 levels were significantly lower among patients receiving immunomodulatory therapy compared those who were not [(67.4 pg/ml (95%CI: 53.1-81.7) vs 106.6 pg/ml (95%CI: 71.4-141.8); p=0.0057)]. There was no difference in IL-22 levels with regards to treatment [(291.1 pg/ml (95%CI: 201.9-380.2) vs 230.1 pg/ml (95%CI: 98.4-361.7); p=0.64)]. In addition, among patients on immunomodulatory therapy, patients with quiet disease had much lower levels of IL-17. Uveitis patients with associated systemic autoimmune disease had higher levels of serum IL-17 but not IL-22.
Conclusions:
Serum IL-17 levels are lower in patients with quiet uveitis, particularly those on immunomodulatory therapy. Results suggest that serum IL-17 levels can be an indicator for systemic disease association in uveitis patients and shows promise to be potentially used as a biomarker for disease status or response to therapy.
Keywords: cytokines/chemokines • uveitis-clinical/animal model • inflammation