Semen Cuscutae has been using as a tonic for nourishing the liver and kidneys. However,
the immunoregulatory effect of Semen Cuscutae is rarely studied. Dendritic cells (DCs)
play a critical role in initiating immune response. Thus, DCs are regarded as a major
target of immunomodulator for controlling harmful immune responses. In this study,
we examined the effect of Semen Cuscutae on mouse bone marrow-derived DC activation.
We found that the n-butanol and methanol partitions of Semen Cuscutae potentially
suppressed LPS-induced DC activation. HPLC chromatography showed that several flavonoids
might be responsible for this inhibitory activity. Then, we identified that kaempferol
was the major flavonoid to inhibit LPS-induced DC activation by reducing the production
of pro-inflammatory cytokines and maturation. The inhibitory ability of kaempferol
was tested at the concentration of 10 ug/ml. Importantly, consistent to the in vitro results, the recall assay in vivo showed that kaempferol significantly inhibited the T cell proliferation, indicating
that kaempferol abrogated the ability of LPS-stimulated DCs to induce Ag-specific
T cell activation, both in vitro and in vivo. Therefore, we demonstrate that Semen Cuscutae has immunosuppressive activity for
the first time. In addition, we are the first group to report that kaempferol attenuates
the DC activation and could potentially be applied in the therapy for inflammatory
and autoimmune diseases.
References: 1. Yu YL, et al., 2009. Eur J Immunol. 39(9):2482–2491.
