Stemucronatoside L, a Pregnane Glycoside from the Roots of Stephanotis mucronata, Inhibits Th1/Th2 Immune Responses in vitro.

Chem Biodivers. 2009 Jun 23; 6(6): 916-923Chen FY, Ye YP, Sun HX, Li XY, Shi HStemucronatoside L (SML), isolated from Stephanotis mucronata, could suppress the activation of T cells in vitro. However, the mechanisms responsible for its immunosuppressive activity remain poorly understood. The purpose of this study was to investigate whether SML could suppress Th1/Th2 immune responses and to characterize the cellular mechanisms involved. Effects of SML on T-lymphocyte subsets and the production of Th1 cytokines IL-2 and IFN-gamma, and Th2 cytokines IL-4 and IL-10 from ConA-stimulated mice splenocytes were detected by flow-cytometric analysis and ELISA method, respectively. Furthermore, effects of SML on mRNA expression level of Th1/Th2 cytokines and transcription factors T-bet and GATA-3 were evaluated by RT-PCR analysis. SML not only significantly decreased the percentage of CD4(+) T cells and the CD4(+)/CD8(+) ratio, but reduced the production of Th1/Th2 cytokines in a concentration-dependent manner. The mRNA expression levels of Th1/Th2 cytokines and transcription factors (T-bet and GATA-3) were also suppressed by SML. These results suggested that SML could simultaneously inhibit Th1/Th2 immune responses by suppressing gene expression of Th1/Th2 cytokines and transcription factors.