Increased serum caspase-1 in adult-onset Still's disease

Background Caspase-1 is a crucial component in the inflammasome activation cascade. This study evaluated the potential of serum caspase-1 level as an inflammatory biomarker in patients with adult-onset Still's disease (AOSD). Methods The study included 51 consecutive patients diagnosed with AOSD based on the Yamaguchi criteria, 66 patients with rheumatoid arthritis (RA) as disease control, and 36 healthy controls (HCs). Serum caspase-1 concentrations were measured using enzyme-linked immunosorbent assay. The serum 69 cytokine levels were analyzed using a multisuspension cytokine array in patients with AOSD, and a cluster analysis of each cytokine was performed to determine specific molecular networks. Results Patients with AOSD had significantly increased serum caspase-1 levels versus patients with RA (p < 0.001) and HCs (p < 0.001). Additionally, serum caspase-1 demonstrated significant positive correlations with AOSD disease activity score (Pouchot score, r = 0.59, p < 0.001) and serum ferritin (r = 0.54, p < 0.001). Furthermore, among patients with AOSD, significant correlations existed between serum caspase-1 and inflammatory cytokines, including interleukin-18. Immunoblot analysis detected the cleaved form of caspase-1 (p20) in the serum of untreated patients with AOSD, not in those from patients with inactive AOSD receiving immunosuppressive treatments. Conclusions Caspase-1 is a useful biomarker for AOSD diagnosis and monitoring. Caspase-1 activation could be correlated with the inflammatory component of AOSD, specifically through proinflammatory cytokine induction via inflammasome activation cascades.