Daphnetin improved URSA model mice fertility by regulating the imbalance of Th17/Treg cells

We have previously reported daphnetin had a positive effect on improving the balance of T helper 17 (Th17) cells and Foxp3 + regulatory T cells (Treg) in the peripheral blood mononuclear cells from patients with unexplained recurrent pregnancy loss, but its definite mechanism remains elusive. This study aims to deeply explore the regulatory effect of daphnetin on the imbalance of Th17/Treg cells in the unexplained recurrent spontaneous abortion (URSA) model mice. Forty mice were divided into four groups: normal pregnancy (control), URSA model, daphnetin low dose (1mg/ (kg· day) and daphnetin high dose (4mg/ (kg· day). The proportion of Th17/Treg cells in peripheral blood mononuclear cells (PBMCs) was detected by flow cytometry. The level expression of orphan nuclear receptor γ t (RORγt), signal transduction and transcriptional activator 3 (STAT3), forked transcription factor P3 (FoxP3) and signal transduction and transcriptional activator 5 (STAT5) in decidual tissues were detected by real-time PCR. Then, we alculated Embryo absorption rate and observed the ultrastructural changes of decidual tissues by transmission electron microscope. Compared with the URSA model group, daphnetin significantly decreased the ratio of Th17/Treg in PBMCs. At the same time, daphnetin decreased the expression of Th17-related cytokines RORγt and STAT3 and increased the expression of Treg-related cytokines FoxP3 and STAT5. What's more, daphnetin decreased the absorption rate of embryo and improved the ultrastructure of decidual tissue of URSA model mice. The above data showed that daphnetin could improve the imbalance of Th17/Treg cells of URSA model mice by regulating RORγt, STAT3, FoxP3 and STAT5, which finally repair damaged decidual tissue and decrease the absorption rate of embryo of URSA model mice. Daphnetin may provide a new approach for URSA treatment in the future.