Figure 3. Bile Acids Activate the NLRP3 Inflammasome in a Calcium Influx-Dependent Manner.

(A-C) Intracellular calcium concentrations detected by a fluorescent probe Fluro-4AM together with probenecid; THP-1 cells were stimulated with 200 μM bile acids (A) and 2 mM ATP was spiked in 75 s before (B) or 150 s after bile acid treatment (C). Data are presented as mean value of n = 5; error bars were not shown for clarity.

(D-F) LPS-prim edTHP-1 cells treated with 100 μM bile acid s for 4 hr with or with o u t 1 mM ATP spiked in at last30 min. Cells were pretreated with 50 μM BAPTA-AM or 2.5 μM ionomycin for 30 min.

(G) Representative immunofluorescence images of calcium influx in THP-1 cells that were stimulated with 200 μM bile acids or 2 mM ATP for 5 min. MitoTracker and Fluro-4AM/probenecid were loaded 45 min prior to stimulation.

(H and I) Representative immunofluorescence images of caspase 1 in THP-1 cells that were stimulated with 200 μM bile acids for 4 hr(H) or primed with LPS for 2 hr and then stimulated with 100 μM bile acids for 4 hr or 1 mM ATP for 30 min. Scale bars, 20 μm; one representative image of three independent experiments is shown.

Data are representative of at least two independent experiments and expressed as mean ± SEM (n = 3). **p < 0.01, *p < 0.05 between indicated groups; n.s. represents no significance; two-tailed Student’s t test.

See also Figure S3.