Figure 6

DHA inhibits caspase-1 activity and IL-1β maturation. WT and NLRC4^+/− HepG2 cells were treated with different dose of PA with or without DHA preincubation and cells were homogenized in lysis buffer. (A) Caspase-1 activity was determined using colorimetric assay based on the cleavage of substrate Ac-YVAD-pNA. The results were expressed as fold over untreated WT cells. *P < 0.05, **P < 0.01 compared with untreated cells; #P < 0.01 versus 0.4 mM PA-treated cells. (B) Immunoblot analysis showing caspase-1 cleavage and active IL-1β accumulation. This gel is the representative image of three independent experiments (upper panel). Quantified data of protein levels indicates in lower panel. The values of density of proteins were all justified with β-actin. The relative density ratios of untreated WT cells were set at a value of 1.0. The values represent the mean ± S.E (*P < 0.05, **P < 0.01 compared with WT cells treated with 0.4 mm PA for the ratio of caspase-1/procaspase-1; #P < 0.01 versus 0.4 mM PA-treated WT cells for the ratio of IL-1β/pro-IL-1β).