Figure 4.

SAA/MSU-induced IL-1β processing is dependent on caspase-1. A. Synovial fibroblasts were untreated or pretreated with SAA (2 μg/ml) for 12 h. Cells were stimulated with the indicated concentrations of MSU for 24 h. Supernatants were analyzed by immunoblot for the presence of procaspase-1 (p45) and cleaved caspase (p20). Three experiments were performed using different synovial fibroblasts and a representative result is shown. B. Synovial fibroblasts were untreated or pretreated with SAA (2 μg/ml) for 12 h. Cells were stimulated with MSU in the presence or absence of z-YVAD-fmk (10 μM) for 24 h. Supernatants were analyzed by immunoblot analysis for the presence of mature IL-1β. Two experiments were performed using different synovial fibroblasts and a representative result is shown.