The Mechanism Of IL-10 In Abnormal Pregnancy Improvement Following T. Gondii Infection

Problem:To understand the mechanism of IL-10 in abnormal pregnancy improvement following Toxoplasma gondii (T. gondii) infection.Methods of study:To explore the influence of IL-10 on the activating receptor NKG2D and the inhibitroy receptor NKG2A on dNK cells, whether participate in the improvement of the adverse pregnancy outcomes following T. gondii infection. C57BL/6 wild type (WT) mice and IL-10 deficiency (IL-10-/-) mice were randomly divided into the control group, the infection group, and the infection treated with recombinant mouse IL-10 (rIL-10) group (rIL-10-treated group) respectively. The infection group and rIL-10-treated group were infected with 400 T. gondii tachyzoite on gestational day (gd) 7. On gd 6 and 8, the rIL-10-treated group was administrated with 1μg rIL-10 via a tail vein injection. On gd 12, the mice in each group were euthanized. Record the pregnancy outcomes in each group. Single-cell suspensions were prepared from placenta and uterus. Levels of NKG2D and NKG2A on dNK cells were detected by flow cytometry.To explore the influence of IL-10 on expression of IFN-γ whether involved in the improvement of the adverse pregnancy outcomes following T. gondii infection. The animal models as shown upon were established, and the placental supernatants were collected. The expression of IFN-γ in placental supernatants was investigated by ELISA. Single-cell suspensions were prepared from placenta and uterus, and IFN-γ expression in dNK cells was investigated by flow cytometry.Results:The infection group had malaise, extrados, and erected fur compared with controls; most fetuses and placentas from infected mice were evidently necrotic, hemorrhagic, and resorbed compared to controls. The resorption rate of infection group was higher, and the weight of placenta and fetuses were less than that of controls. However, the hemorrhagic, necrotic, and resorbed phenotype was obviously improved in rIL-10-treated group than that of the infection groups. In addition, the rate of fetal loss of IL-10-treated group was less, and the weight of placenta and fetuses was higher than that of T. gondii infection group. In WT mice, the expression of NKG2D and NKG2A were significantly up-regulated in infection group compared to controls. Moreover, the increased degree of NKG2D was higher than that of NKG2A. In IL-10-treated group, the level of NKG2D was down-regulated, while NKG2A expression was up-regulated than that of infection group. In IL-10-/- mice, the expression of NKG2A and NKG2D exhibited no significant changes in infection group compared with controls and were increased in IL-10-treated group than that of infection group. In WT mice, the level of IFN-γ in dNK cells and placental supernatants was significantly elevated in infection group compared with controls; while was decreased in IL-10-treated group than that in infections. In IL-10-/- mice, the level of IFN-γ in placental supernatants was significantly elevated in infection group compared with controls; while the level of IFN-γ in dNK cells was no significant changes in infection group compared with controls. In IL-10-treated group, the level of IFN-γ in placental supernatant and dNK cells was elevated compared with infections.Conclusion:1. IL-10 could up-regulate the expression of NKG2A and down-regulate NKG2D expression, which may reverse the imbalance between inhibitory receptor and activating receptor induced by T. gondii infection, and then restore the adverse pregnancy outcomes with T. gondii infection.2. IL-10 could down-regulate the IFN-γ expression both in the placental supernatant and in dNK cells, correcting the imbalance of Th1/Th2 ratio induced by T. gondii infection.