Immunomodulatory Effects Of Dendritic Cells By Astilbin And Its Mechanism For The Treatment Of Inflammatory Bowel Disease

[Aims]IBD is currently regarded as a global disease, but the therapies have significant limitations with regard to safety, efficacy, and applicability, expensive and so on. Astilbin, a major bioactive compound from Rhizoma smilacis glabrae, has been reported to possess immunosuppressive properties. Our study first investigate the effect and mechnism of astilbin on DSS-induced colitis in mice.[Methods]The mouse model of DSS-induced colitis was established to observe the effect of astilbin in vivo. The levels of serum cytokines in DSS-treated mice were detected by ELISA. Splenic dendritic cells and CD4+CD25+Foxp3+T cells from DSS-induced colitis were analyzed by flow cytometry. Different concentrations of astilbin were added on splenocyte and RAW264.7. The design of using fluorescence probe DCFH-DA to label the cells was provided in order to discover the intracellular ROS level by flow cytometry. Meanwhile the cytokines (IL-10, TGF-P, IL-12/IL-23p40) of splenic dendritic cells and RAW264.7were analyzed by flow cytometry. Isolate and induct human monocyte-derived DCs with rhIL-4and GM-CSF. The phenotypes of human monocyte-derived DCs from IBD patients were compared with healthy volunteers. The phenotype and cytokines secretion of immature dendritic cells from IBD patients stimulated with astilbin were analyzed by flow cytometry. Bone marrow-derived dendritic cells pretreated with astilbin were cocultured with splenic CD4+T cells. The absolute number of Tregs and the frequency of CD4+IFN-γ+T cells were detected by flow cytometry.[Results]1. Astilbin suppressed the onset and severity of colitis in mice treated with DSS.2. Astilbin treatment resulted in an increase in the serum level of IL-10and TGF-β.3. Induced generation of regulatory DCs and CD4+CD25+Foxp3+T cells in mice with DSS-induced colitis by astilbin treatment4. Astilbin decreased CD86, IL-1β, IL-12p40expression of splenic DCs and increased the production of IL-10and TGF-β with a dose dependent manner.5. Intracellular ROS level and the inflammatory cytokine of RAW264.7were inhibited and the regulatory cytokines were promoted by astilbin treatment.6. The CD86expression of human monocyte-derived DCs from IBD patients was higher than healthy individuals, meanwhile astilbin inhibited the expression of CD86, IL-1β, IL-12p40and promoted the production of IL-10, TGF-P in human monocyte-derived imDCs from IBD patients.7. DCs pretreated with astilbin induced the generation of CD4+CD25+Foxp3+T cells and inhibitd the production of IFN-y in CD4+T cells.[Conclusions]Preliminary results shows that astilbin possess protective effect of DSS-induced colitis through inducing regulatory function of dendritic cells. Meanwhile astilbin could regulate the function of human monocyte-derived imDCs from IBD patients. DCs pretreated with astilbin induced the generation of CD4+CD25+Foxp3+T cells.