Figure 7.

Schematic diagram of IL-27 and Gal-9 promoting Tim-3⁺ Treg cell accumulation in the decidua. (A and B) IL-27 secreted by trophoblast cells induces Tim-3 expression on decidual CD4⁺ T cells, then Gal-9 activates the Tim-3 signal pathway promoting Treg cell differentiation. In the presence of Gal-9, effector T cells might be more fragile than Treg cells. In a normal pregnancy, Gal-9 expression gradually increases, while IL-27 expression remains stable from early pregnancy to late pregnancy. (C) In RPL, insufficient Tim-3-Gal-9 engagement due to decreased Tim-3 expression leads to reduced Treg cell proportions.