Glycyrrhizin Inhibits Interleukin-8 Production and Nuclear Factor?κB

　　Abstract. This study was designed to examine the glucocorticoid-like inhibitory effect ofglycyrrhizin （GL） on interleukin （IL）-8 production in A549 lung epithelial cells. GL， as well asdexamethasone （DEX） inhibited both tumor necrosis factor （TNF）-α– and IL-1β–induced IL-8 production， mRNA expression， and promoter activity in A549 cells. Both GL and DEX inhibited transactivation of nuclear factor （NF）-κB， without inhibiting translocation of the NF-κB p65 subunit to the nucleus. However， the effect of GL was insensitive to RU486， a GR antagonist， and to GR knockdown by siRNA. Furthermore， only GL inhibited DNA binding of p65 to the IL-8 promoter region. These findings indicated that GL had a glucocorticoid-like inhibitory effect on IL-8 production via a mechanism that differs from that of glucocorticoids.