Upregulation of Tim‐3 Expression at Feto‐maternal Interface May Explain Embryo Survival in the CBAxDBA/2 Model of Abortion

Problem To understand the mechanisms of action of Tim‐3 at the maternal‐fetal interface and explore how Tim‐3 might be involved in the pathogenesis of abortion by constructing an in vitro trophoblast‐lymphocyte system. Methods of Study Female CBA /J × male DBA /2 matings were used as the abortion‐prone model and CBA /J × male BALB /c matings as control. The expression of Tim‐3 at the maternal‐fetal interface and in the peripheral blood lymphocytes was measured by immunohistochemistry and Western blotting. The proliferation index of lymphocytes and levels of Th1/Th2‐derived cytokines in peripheral blood and in the co‐culture system were determined using CCK ‐8 assay and ELISA , respectively. Results The expression level of Tim‐3 was higher in abortion‐prone matings than that of control ( P < .05). A preponderance of Th1 was observed in the co‐culture system in the abortion‐prone mating group. Recombinant Tim‐3 Ig reversed the imbalance of Th1/Th2 immunity of abortion‐prone matings by suppressing the secretion of IFN ‐γ and IL ‐2 but had no direct effect on the generation of IL ‐4. Conclusion Tim‐3 might contribute to successful pregnancy by restraining Th1 bias, and the maternal immune system might develop a strategy including upregulation of Tim‐3 at the maternal‐fetal interface and in peripheral blood so as to maintain moderate inflammatory responses against miscarriage.