Fig. 2.

MSU activates IL-1β signaling proteins in primary human macrophages and coordinates with IL-1β to induce cytokine production in primary human synovial fibroblasts. a Primary PBMC-derived human macrophages (2 × 10⁶/well) in six-well plates were stimulated with MSU (100 µg/ml) for 30 min. Cell lysates were prepared to detect MyD88 and phosphorylated and total IRAK1 and TAK1. b Human NLSFs were treated with MSU (25–200 μg/ml) or IL-1β (10 ng/ml) for 30 min. Cell lysates were prepared to study activation of the signaling proteins MyD88, IRAK1, TRAF6, TAK1, and TAB2. b Human NLSFs were stimulated with MSU (25–100 μg/ml) for 24 h. Conditioned media were collected and further utilized to quantitate IL-6 and IL-8 production. c–f Human NLSFs were treated with IL-1β (1 ng/ml) alone or with MSU (25–100 μg/ml) for 24 h, and the conditioned media were collected and used for the estimation of IL-6, IL-8, and ENA-78 production. The results shown in b–f were obtained from the experiment on NLSFs obtained from three different donors and are presented as the mean ± SEM. *p < 0.05 or **p < 0.01 vs. NS (not significant); ^#p < 0.05 or ^##p < 0.01 vs. IL-1β