Silibinin inhibits the production of pro-inflammatory cytokines through inhibition of NF-κB signaling pathway in HMC-1 human mast cells

BACKGROUND: Silibinin is the major active molecule of silymarin, the mixture of flavonolignans extracted from Cirsium japonicum. It has been used for the treatment of hepatitis and inflammation-related diseases. In the present study, the effects of silibinin on allergic inflammation and its signaling were investigated in the induced human mast cells. METHODS: Cell growth inhibition induced by silibinin was measured by MTS assay. Histamine release was measured by enzyme immunoassay. The tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6), and interleukin-8 (IL-8) secreted protein levels and mRNA levels were measured by the ELISA assay and RT-PCR, respectively. The NF-κB promoter activity was examined by a luciferase assay. RESULTS: Silibinin suppressed the growth of HMC-1 cells and also reduced the production and mRNA expression of pro-inflammatory cytokines such as TNF-α, IL-6, and IL-8. Moreover, silibinin inhibited the nuclear translocation of nuclear factor (NF)-κB through inhibition of the phosphorylation of IκBα and suppressed NF-κB transcriptional activity in stimulated HMC-1 cells. CONCLUSIONS: Taken together, these results indicate that silibinin inhibits the production of pro-inflammatory cytokines through inhibition of NF-κB signaling pathway in HMC-1 human mast cells, suggesting that silibinin could be used for the treatment of mast cell-derived allergic inflammatory diseases.