Glycyrrhizin enhances interleukin-10 production by liver dendritic cells in mice with hepatitis

Background. Glycyrrhizin (GL), an aqueous extract of licorice root, is known to have various immune-modulating and biological response-modifier activities. GL is used in patients with hepatitis to reduce the activity of liver inflammation; however, the mechanism underlying the anti-inflammatory activity of GL is poorly understood. As antigen-presenting dendritic cells (DC) in the tissue play a major role in the regulation of the inflammatory mucosal milieu during tissue inflammation, we studied whether the function of liver DC was altered by GL therapy in a murine model of concanavalin-A (Con A)-induced hepatitis. Methods. Liver DC were propagated from control mice or mice with Con-A-Induced hepatitis, and the effect of GL on liver DC was evaluated in vivo and in vitro. Results. The levels of interleukin (IL)-10 produced by liver DC were significantly lower in mice with Con-A-induced hepatitis compared with control mice. However, treatment with GL caused increased production of IL-10 in mice with Con A-induced hepatitis. The increased production of IL-10 by mice with Con A-induced hepatitis was also confirmed in vitro by culturing liver DC with GL. Conclusions. This study indicates that increased production of IL-10 by liver DC due to GL administration may be involved in downregulation of the levels of liver inflammation in mice with Con A-induced hepatitis.