Oridonin promotes CD4+/CD25+ Treg differentiation, modulates Th1/Th2 balance and induces HO-1 in rat splenic lymphocytes

. Objective and design: Oridonin is an ent-kaurene diterpenoid extracted from Isodon Serra , and we have previously demonstrated its immunosuppressive effect. Our goal was to study how Oridonin impacts CD4 + /CD25 + regulatory T cells (Tregs) and Th1/Th2 balance, as well as its effect on the anti-inflammatory target HO-1. Material: Splenic lymphocytes were prepared from male 6–8-week-old SD rats. Treatment: Cells were cultured in four groups as Oridonin -L ( Oridonin 12.5 μmol/l), Oridonin -H ( Oridonin 25 μmol/l), Cobalt protoporphyrin (Copp 50 μmol/l) and control (DMSO) with stimulation of ConA (5 μg/ml) for 48 h or with no stimulation for 12 h. Method: We set up a model of Th1 polarization in vitro using ConA stimulation; ratios of CD4 + /CD25 + Tregs (confirmed by the expression of Foxp3) were measured by flow cytometry, and levels of IL-2, IFN-γ, TGF-β and IL-10 were measured by ELISA. In addition, HO-1 expression was measured without stimulation with ConA by RT-PCR and Western blotting, and HO-1 level in vitro was then measured by enzyme activity assay. p