Fig. 1.

Expression of Siglec-14 on macrophages increases IL-1β secretion through NLRP3 inflammasome activation. a THP1-EV, THP1-Sig14 and THP1-Sig5 cells were treated with 25 nM of phorbol-12-myristate-13-acetate for 48 h and stimulated with 5 mM of ATP or 10 μM of nigericin for 30 min then incubated for additional 2 h; secreted IL-1β in supernatants was determined by ELISA. b The amount of secreted mature IL-1β in the supernatants of a were determined using IL-1β sensor cells (Invivogen) and optical density (OD) measurements at 655 nm. c Cells were treated with caspase-1 inhibitor Ac-YVAD-CMK (YVAD), NLRP3 inhibitor CRID3 sodium salt (CRID3) or mock control for 1 h and stimulated with ATP or nigericin for an additional 2 h followed by ELISA to determine the secreted IL-1β level in supernatants. d Cells were treated with PBS, K⁺ buffer or Na⁺ buffer for 2 h and exposed to nigericin or buffer control for an additional 2 h. Culture supernatants were used to determine secreted IL-1β levels by ELISA. Error bars represent the SD of data means from 3 independent experiments. Significance of p values was classified as follows: * p < 0.05, ** p< 0.005, *** p < 0.001. EV, empty vector; IL-1β, interleukin-1β; unstim., unstimulated; inhib, inhibition.