The role of icaritin in regulating Foxp3/IL17a balance in systemic lupus erythematosus and its effects on the treatment of MRL/lpr mice

•Herb derived factor ICT can regulate Foxp3/IL17a balance and Treg function.•ICT regulates Foxp3/IL17a balance in part through epigenetic regulation of histone methylation and control of transcriptional factors such as STAT5b.•ICT has modest effect on renal disease on the MRL/lpr murine lupus model.

Systemic lupus erythematosus (SLE) is a female predominant autoimmune disease characterized by multi-organ dysfunctions. However, current available therapies control the disease at the cost of many potential adverse effects. The development of safer and more effective therapies for SLE is a critical unmet need. Icaritin (ICT) is an active monomer extracted from Chinese herbals named the Epimedium genus. In this study, we found that ICT exhibited the capacity of regulating Foxp3/IL17a balance, enhancing Treg cell suppressive activities, and inhibiting over-activation of CD4+ T cells from SLE. We also observed that ICT regulated Foxp3/IL17a balance by increasing STAT5b expression and histone methylation modification. Subsequent experiments further confirmed that ICT-treated mice exhibited amelioration of renal damages and suggested that ICT may be a potential new drug for the treatment of SLE.