Paeonol reduces IL-β production by inhibiting the activation of nucleotide oligomerization domain-like receptor protein-3 inflammasome and nuclear factor-κB in macrophages.

Interleukin-1β, a key cytokine in gouty inflammation, is precisely regulated by the NLRP3 inflammasome and NF-κB. Our previous study demonstrated that paeonol suppressed IL-1β production in rats with monosodium urate (MSU)-induced arthritis. Whether NLRP3 inflammasome or NF-κB is responsible for the anti-inflammatory effect of paeonol remains unclear. In this study, J774A.1 cells induced by lipopolysaccharide (LPS) plus MSU, was used to investigate the effect of paeonol on NLRP3 inflammasome activation, and J774A.1 cells induced by LPS alone were used to investigate the effect of paeonol on NF-κB activation. In J774A.1 cells induced by LPS plus MSU, paeonol decreased the levels of IL-1β and caspase-1 and reduced the MSU-induced interaction of pro-caspase-1 and apoptosis-associated speck-like protein containing caspase recruitment domain (ASC), but did not affect the levels of pro-IL-1β and pro-caspase-1. In J774A.1 cells induced by LPS alone, paeonol reduced the levels of IL-1β, NLRP3, p-IKK, p-IκBα, and p-p65, but did not affect ASC levels. Paeonol also promoted the content of IκBα and retained more p65 in the cytoplasm. Furthermore, paeonol reduced the DNA-binding activity of p65 and lowered the levels of p-JNK, p-ERK, and p-p38. These results suggest that paeonol inhibits IL-1β production by inhibiting the activation of NLRP3 inflammasome, NF-κB, and MAPK signaling pathways.