OBJECTIVETo study the effect of coixenolide on Foxp3+ CD4+ CD25+ regulatory T cells (Treg) in collagen induced arthritis (CIA) mice, and to explore its possible mechanism for treating rheumatiol arthritis.

METHODSFive mice were recruited as a normal control group from 25 mice, and the rest 20 were used in CIA modeling. After successful modeling they were randomly divided in the model control group and the coixenolide group, 10 in each group. Coixenolide injection at 25 mL/kg was intraperitoneally injected to mice in the coixenolide group, while normal saline at 25 mL/kg was intraperitoneally injected to mice in the normal control group and the model control group. The injection lasted for 21 days. Scoring for CIA was performed after injection and arthritis index was calculated. The peripheral blood Foxp3+ CD4+ CD25+ Treg ratio was determined by flow cytometry (FCM).

RESULTSCompared with the normal control group, the arthritis index obviously increased in the model control group (P < 0.01). The arthritis index obviously decreased more in the coixenolide group than in the model control group (P < 0.01). Foxp3+ CD4+ CD25+ Treg levels obviously decreased more in the model control group than in the normal control group (P < 0.01 ). Foxp3+ CD4+ CD25+ Treg levels obviously increased more in the coixenolide control group than in the model control group (P < 0.01).

CONCLUSIONCoixenolide could up-regulate Foxp3+ CD4+ CD25+ Treg ratios in CIA mice, which might play certain immunoregulation roles in the incidence of CIA.