Luteolin suppresses IL-31 production in IL-33-stimulated mast cells through MAPK and NF-κB signaling pathways.

IL-31 and IL-33 are cytokines, which are expressed in many inflammatory and pathological disorders, thus suggesting an IL-31/IL-33 axis interaction in pathological diseases. Luteolin from natural products is known for its anti-inflammatory activities associated with the regulation of inflammatory signaling pathways. Here, we investigated the effects of luteolin in the regulation of IL-33-stimulated production and secretion of IL-31 in HMC-1.2 mast cells. Human mast cells (HMC-1.2) were treated with luteolin and stimulated with IL-33. Real-time PCR was used to measure IL-31 mRNA expression. Western blot and immunofluorescence assays were used to measure IL-31 expression. ELISA techniques were used to measure IL-31 secretion and NF-κB-DNA-binding activities. The results revealed that luteolin inhibited the expression of IL-31 in IL-33-stimulated HMC-1.2 cells at the mRNA and protein levels. Also, Luteolin inhibited the secretion of IL-31 into the cell culture media of the IL-33-stimulated HMC-1.2 cells. Further findings demonstrated that luteolin inhibited the activation of ERK, JNK, p38, and NF-κB p65 in the IL-33-stimulated HMC-1.2 cells. In addition, luteolin also prevented the nuclear translocation and binding of p65 to its DNA-binding site. Based on the results, luteolin may be considered as a potential therapeutic or functional food agent for the prevention and/or treatment of IL-31 and IL-33-related diseases.