Dioscin alleviates aplastic anemia through regulatory T cells promotion.

Objectives: Aplastic anemia (AA) is one of the immune-mediated bone marrow failure disorders caused by multiple factors, including the inability of CD4 + CD25 + regulatory T cells (Tregs) to negatively regulate cytotoxic T lymphocytes (CTLs). Dioscin is a natural steroid saponin that has a similar structure to steroid hormones. The purpose of this study is to look into the effect of Dioscin on the functions of CD4 + CD25+ Tregs in the AA mouse model and explore its underlying mechanism.Methods: To begin with, bone marrow failure was induced through total body irradiation and allogeneic lymphocyte infusion using male Balb/c mice. After 14 consecutive days of Dioscin orally administrated, the AA mouse model was tested for complete blood counts, HE Staining of the femur, Foxp3, IL-10 and TGF-ß. Then CD4 + CD25+ Tregs were isolated from splenic lymphocytes of the AA mouse model, Tregs and the biomarkers and cytokines of Tregs were measured after 24 h of Dioscin intervention treatment in vitro.Results: Dioscin promotes the expression of Foxp3, IL-10, IL-35 and TGF-ß, indicating its Tregs-promoting properties. Mechanistically, the administration of Dioscin resulted in the alteration of CD152, CD357, Perforin and CD73 on the surface of Tregs, and restored the expression of Foxp3.Conclusion: Dioscin markedly attenuated bone marrow failure, and promoted Tregs differentiation, suggesting the maintenance of theimmune balance effect of Dioscin. Dioscin attenuates pancytopenia and bone marrow failure via its Tregs promotion properties.

[Effect of Xijiao Dihuang Combined Prescription on Human Dendritic Cell Function Induced by Lipopolysaccharide].

OBJECTIVE: To observe the effects of drug-containing serum of Xijiao Dihuang combined prescription(XJDH) on the related functions of dendritic cells(DCs) induced in vitro, and to explore the mechanisms underlying the effectiveness of XJDH treatment on primary immune thrombocytopenia(ITP). METHODS: Peripheral blood samples were colle-ted from 6 healthy volunteers. Mononuclear cells were isolated by density gradient centrifugation, and CD14+ mononuclear cells were collected by the magnetic separation technique. CD14+ mononuclear cells were induced into immature DCs by recombinant human granulocyte-macrophage colony stimulating factor (GM-CSF) and recombinant human interleukin 4 (IL-4). Immature DCs were divided into three groups: control group, model group and XJDH group. CCK-8 assay was used to determine the intervention concentration and time of drug-containing serum. Lipopolysaccharide(LPS) with the final concentration of 1 µg/ml was added to model group and XJDH group respectively for 24 h to induce DCs maturation. Normal rat serum was added to control group and model group, and XJDH was added to XJDH group for 24 h. Flow cytometry was used to detect the levels of CD80, CD83 and HLA-DR on the surface of DCs. Western blot was used to detect the expression of TLR4 and NF-κB, and levels of IL-6, IL-12 and TNF-α in cell supernatant was detected by ELISA. RESULTS: Compared with the control group, LPS stimulation increased the expression of CD80, CD83 and HLA-DR, with subsequent increasing expression of TLR4 and NF-κB, as well as IL-6, IL-12 and TNF-α increased(P<0.05). In comparison with model group, the expression of DCs surface molecules CD80, CD83 and HLA-DR, DCs' expression of TLR4 and NF-κB protein, and the levels of IL-6, IL-12 and TNF-α in the cell supernatant of XJDH group decreased after the intervention of XJDH (P<0.05). CONCLUSION: Drug containing serum of Xijiao Dihuang combined prescription can down-regulate TLR4/NF-κB signaling pathway related protein expression, inhibit DCs maturation, and reduce proinflammatory factor secretion, which may be one of the mechanisms of drug-containing serum of Xijiao Dihuang combined prescription in the treatment of immune thrombocytopenia.