Fig. 6: IL-37d attenuated pro-inflammatory cytokines expression in a pSmad3-dependent manner.

a A549 cells pretreated with 2 μM SIS3 or the same amount of vehicle (DMSO) for 1 h were stimulated with IL-1β (10 ng/ml) for another 1 h. The expression of pSmad3 in whole-cell lysates was detected by western blot. (b, c) A549 cells transfected with IL-37d or mock plasmid were pretreated with 2 μM SIS3 or vehicle for 30 min and then stimulated with IL-1β (10 ng/ml) for 6 h. The levels of IL-6 (b) and IL-1α (c) in the culture supernatants were determined by ELISA. d–f A549 cells expressing IL-37d were transfected with 100 nM of human siSmad3 or scrambled control for 48 h and then stimulated with IL-1β (10 ng/ml) for 6 h. Smad3 knockdown efficiency was analyzed by western blot (d). The levels of IL-6 (e) and IL-1α (f) in the culture supernatants were determined by ELISA. *P < 0.05, ***P < 0.001; ns, no significant difference. Data are shown as the mean ± SEM from three independent experiments