Potential role of Th17 cells in the pathogenesis of adult-onset Still's disease.

OBJECTIVE To investigate the potential role of Th type 17 (Th17) cells and Th17-related cytokines in the pathogenesis of adult-onset Still's disease (AOSD). METHODS The frequencies of circulating Th17 cells in 24 patients with active untreated AOSD, 16 patients with active SLE and 12 healthy volunteers were determined using intracellular cytokine staining and flow cytometry. Serum levels of Th17-related cytokines, including IL-1β, IL-6, IL-17, IL-18, IL-21 and IL-23 were measured by ELISA. RESULTS Significantly higher median frequencies of circulating Th17 cells were found in active untreated AOSD patients (1.01%) and active SLE patients (1.26%) than in healthy volunteers (0.12%, both P<0.001). The frequencies of circulating Th17 cells were positively correlated with activity score (r=0.527, P<0.01) and serum ferritin levels (r=0.724, P<0.001) in AOSD patients, and correlated with SLEDAI (r=0.663, P<0.01) in SLE patients. Additionally, the frequencies of circulating Th17 cells were positively and significantly correlated with serum levels of IL-1β, IL-6, IL-17, IL-18, IL-21 and IL-23 in both AOSD and SLE patients. The frequencies of circulating Th17 cells and serum IL-17 levels significantly decreased after effective therapy in AOSD patients (both P<0.001). CONCLUSION Elevated frequencies of circulating Th17 cells and a positive correlation with disease activity in our AOSD patients suggest that Th17 cells contribute to the pathogenesis of this disease. Dysregulation of Th17 cells may be a common pathogenic mechanism that underlies the development of both AOSD and SLE.