CB2R negatively regulates NLRP3 inflammasome activation in peritoneal macrophages stimulated with LPS/DSS.

After lipopolysaccharides (LPS, 10 ng/ml) priming for 1 h, peritoneal macrophages were stimulated with 3% dextran sulphate sodium (DSS) in the presence or absence of HU 308 (10 μM) for 24 h. In another set of experiments, peritoneal macrophages from wild-type (WT) mice and cannabinoid receptor 2 (CB2R) knockout (KO) mice were isolated and stimulated with/without LPS/DSS for 24 h. The expression of NLRP3, Casp-1 p20/Casp-1 p45 ratio, proIL-1β and IL-1β mRNA were analyzed. (A and B) Pre-incubated with HU 308 significantly decreased the expressions of NLRP3, Casp-1 p20/Casp-1 p45 ratio, proIL-1β and IL-1β mRNA. n = 6 per group. **P<0.01 vs. control, #P<0.05 vs. LPS/DSS+vehicle; ##P<0.01 vs. LPS/DSS+vehicle. (C and D) The expressions of NLRP3, Casp-1 p20/Casp-1 p45 ratio, proIL-1β and IL-1β mRNA were significantly increased in CB2R KO group. n = 6 per group. *P<0.05 vs. control, **P<0.01 vs. control, #P<0.05 vs. WT, ##P<0.01 vs. WT.