18β-Glycyrrhetinic acid from licorice root impairs dendritic cells maturation and Th1 immune responses.

18β-Glycyrrhetinic acid (β-GA) is a natural triterpenoid compound derived from licorice root. β-GA has been demonstrated to exert antiviral and antitumor effects. However, the effects of the maturation and immunostimulatory functions of dendritic cells (DCs) remain to be clearly elucidated. In this study, we attempted to determine whether β-GA could influence DCs surface molecule expression, antigen uptake capacity, cytokine production and capacity to induce T-cell differentiation. The DCs used in this study were derived from murine bone marrow cells, and were used as immature or lipopolysaccharide (LPS)-stimulated mature DCs. The DCs were then assessed with regard to surface molecules expression, cytokine production, capacity to induce T-cell differentiation and proliferation. β-GA was shown to significantly suppress the expression of surface molecules CD80, CD86, major histocompatibility complex (MHC) class I and MHC class II as well as the levels of interleukin-12 production in LPS-stimulated DCs. Moreover, β-GA-treated DCs showed an impaired induction of the T helper type 1 immune response. These findings provide important understanding of the immunopharmacological functions of β-GA and have ramifications for the development of therapeutic adjuvants for the treatment of DCs-related acute and chronic diseases.