The effect of Brazilian green propolis on regulatory T cells

FoxP3+ regulatory T cells (Tregs) are necessary for suppressing inflammatory diseases and maintenance of immune homeostasis. The suppressive function of Tregs can be used for controlling autoimmune or inflammatory diseases, it is therefore well studied how Tregs can be artificially up- or down-regulated in vitro and in vivo, by using antibodies, chemical compounds, foods and natural resources. Propolis is a famous functional food which has an anti-inflammatory effect. However, influences of propolis on the function of Tregs have not been assessed so far. Here we demonstrated that Brazilian green propolis increases the expression of TNFR2 in Tregs and contributes to the proliferation and suppressive function both in vitro and in vivo. We also found that IRF4/cMyc axis contributed to the expression of TNFR2 in Tregs. These data indicate that TNFR2 regulation by propolis can be a good target for Treg-mediated immune suppression.