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Abstract Recent evidence indicates that macrophages at the maternal–fetal interface adapt to a phenotype characterized by alternative activation (M2 polarization) and exhibit immunosuppressive functions that favor the maintenance of pregnancy. The bias of M2 decidual macrophages toward M1 has been clinically linked to pregnancy-related complications, such as preeclampsia and preterm delivery. The aim of this study was to investigate the effect of Toxoplasma gondii PRU strain infection on the bias of decidual macrophage polarization and its contribution to adverse pregnancy outcomes. A mouse model with adverse pregnancy outcome was established by infection with T. gondii PRU strain and the expression levels of functional molecules in decidual macrophages of mice were measured. The results showed that T. gondii infection caused seriously adverse pregnancy outcome in mice. The placentae of infected mice showed obvious congestion and inflammatory cell infiltration. The expression of CD206, MHC-II, and arginase-1 considered as M2 markers was decreased in decidual macrophages after T. gondii infection, whereas the expression of CD80, CD86, iNOS, and cytokines TNF-α and IL-12 considered as M1 markers was increased. Furthermore, iNOS-positive expression was observed in the decidua basalis of infected mice. Our results indicated that T. gondii infection was responsible for the bias of M2 decidual macrophages toward M1, which changes the immunosuppressive microenvironment at the maternal–fetal interface and contributes to adverse pregnancy outcomes. Highlights • T. gondii infection changes functional molecule expression in decidual macrophages. • T. gondii infection affects iNOS and arginase-1 expression in decidual macrophages. • T. gondii infection alters the pattern of cytokine secretion in decidual macrophages. • T. gondii infection causes M1 polarization of decidual macrophages. • The bias of M1/M2 polarization contributes to adverse pregnancy outcomes. [ABSTRACT FROM AUTHOR]

There is crosstalk between decidual natural killer (dNK) cells and decidual dendritic cells (dDCs) that promotes tolerance of trophoblast cells carrying paternally derived antigens. In the present study, we report that infection of CD1c dDCs with Toxoplasma gondii enhanced gamma interferon (IFN-γ) production by dNK cells in co-culture. The enhancement of IFN-γ production was induced by cytokine IL-12 which increased obviously in co-culture of dDCs with dNK cells following T. gondii infection, and this enhancement largely abrogated when cells were cultured in the presence of an anti-IL-12 antibody. The expression of KIR2DL4 and NKG2D on dNK cells was increased after T. gondii infection, and higher expression of NKG2D was induced by co-cultured dDCs. Neutralization of IL-12 decreased NKG2D expression on dNK cells. Furthermore, dDCs with T. gondii infection increased the cytotoxicity of co-cultured dNK cells against K562 target cells, which was mediated by activating receptor of NKG2D. Thus, T. gondii infection of dDCs enhanced dNK cell IFN-γ production and NKG2D expression, and then led to increased cytotoxicity of dNK cells. The up-regulated dNK cell cytotoxicity at the maternal-fetal interface may contribute to abnormal pregnancy outcomes caused by T. gondii infection in early pregnancy. [ABSTRACT FROM AUTHOR]

Myeloid-derived suppressor cells (MDSCs) play a key role in maintaining maternal-fetal tolerance for a successful pregnancy, but the role of MDSCs in abnormal pregnancy caused by Toxoplasma gondii infection is unknown. Herein, we revealed a distinct mechanism by which T-cell immunoglobulin domain and mucin domain containing protein-3 (Tim-3), an immune checkpoint receptor that balances maternal-fetal tolerance during pregnancy, contributes to the immunosuppressive function of MDSCs during T. gondii infection. The expression of Tim-3 in decidual MDSCs was significantly downregulated following T. gondii infection. The proportion of monocytic MDSCs population, the inhibitory effect of MDSCs on T-cell proliferation, the levels of STAT3 phosphorylation, and the expression of functional molecules (Arg-1 and IL-10) in MDSCs were all decreased in T. gondii-infected pregnant Tim-3 gene knockout (Tim-3KO) mice compared with infected pregnant WT mice. After treatment with Tim-3-neutralizing Ab in vitro, the expression levels of Arg-1, IL-10, C/EBPβ, and p-STAT3 were decreased, the interaction between Fyn and Tim-3 or between Fyn and STAT3 was weakened, and the binding ability of C/EBPβ to the promoters of ARG1 and IL10 was decreased in human decidual MDSCs with T. gondii infection, while opposite results were observed following treatment with galectin-9 (a ligand for Tim-3). Inhibitors of Fyn and STAT3 also downregulated the expression of Arg-1 and IL-10 in decidual MDSCs and exacerbated adverse pregnancy outcomes caused by T. gondii infection in mice. Therefore, our studies discovered that the decrease of Tim-3 after T. gondii infection could downregulate the functional molecules of Arg-1 and IL-10 expression in decidual MDSCs through the Fyn-STAT3-C/EBPβ signaling pathway and weaken their immunosuppressive function, which eventually contribute to the development of adverse pregnancy outcomes. Author summary: Pregnant women in their first trimester with a primary infection of T. gondii are particularly susceptible resulting in a number of serious adverse pregnancy outcomes. Previous studies have shown that T. gondii infection results in the dysfunction of immune cell function at the maternal-fetal interface, which destroys the function of maternal-fetal immune tolerance for a successful pregnancy. MDSCs have an immunosuppressive capacity and play an important role in the maintenance of normal pregnancy. However, the role of MDSCs in the adverse pregnancy outcomes caused by T. gondii infection remains unknown. Here, we analyzed the effect of an immunosuppressive molecule Tim-3 on the function of decidual MDSCs following T. gondii infection. Our results showed that T. gondii infection downregulated the proportion of monocytic MDSCs population, the inhibitory ability of MDSCs on T cell proliferation, the level of STAT3 phosphorylation, and the expression of functional molecules (Arg-1 and IL-10) in MDSCs from the pregnant Tim-3KO mice compared with the pregnant WT mice. Further study showed that the decrease of Tim-3 expression caused by T. gondii infection could downregulate Arg-1 and IL-10 expression in decidual MDSCs via the Fyn-STAT3-C/EBPβ signaling pathway and weaken their immunosuppressive function. This work suggested that MDSCs dysfunction resulting from the downregulation of Tim-3 after T. gondii infection may be an important mechanism of adverse pregnancy outcomes, which may provide theoretical information for prophylactic and/or therapeutic treatments against the infection-related abnormal pregnancy. [ABSTRACT FROM AUTHOR]

Myeloid-derived suppressor cells (MDSCs) play a crucial role in maintaining maternal-fetal tolerance by expressing some immune-suppressive molecules, such as indoleamine 2,3-dioxygenase (IDO). Toxoplasma gondii (T. gondii) infection can break the immune microenvironment of maternal-fetal interface, resulting in adverse pregnancy outcomes. However, whether T. gondii affects IDO expression in dMDSCs and the molecular mechanism of its effect are still unclear. Here we show, the mRNA level of IDO is increased but the protein level decreased in infected dMDSCs. Mechanistically, the upregulation of transcriptional levels of IDO in dMDSCs is regulated through STAT3/p52-RelB pathway and the decrease of IDO expression is due to its degradation caused by increased SOCS3 after T. gondii infection. In vivo, the adverse pregnancy outcomes of IDO−/− infected mice are more severe than those of wide-type infected mice and obviously improved after exogenous kynurenine treatment. Also, the reduction of IDO in dMDSCs induced by T. gondii infection results in the downregulation of TGF-β and IL-10 expression in dNK cells regulated through Kyn/AhR/SP1 signal pathway, eventually leading to the dysfunction of dNK cells and contributing the occurrence of adverse pregnancy outcomes. This study reveals a novel molecular mechanism in adverse pregnancy outcome induced by T. gondii infection. IDO downregulation in dMDSCs induced by Toxoplasma gondii infection regulates expression of TGF-β and IL-10 through the Kyn/AhR/SP1 signal pathway, eventually contributing to the dysfunction of dNK cells. [ABSTRACT FROM AUTHOR]

Background: Toxoplasma gondii infection can cause adverse pregnancy outcomes, such as recurrent abortion, fetal growth restriction and infants with malformations, among others. Decidual myeloid-derived suppressor cells (dMDSCs) are a novel immunosuppressive cell type at the fetal-maternal interface which play an important role in sustaining normal pregnancy that is related to their high expression of the inhibitory molecule leukocyte immunoglobulin-like receptor B4 (LILRB4). It has been reported that the expression of LILRB4 is downregulated on decidual macrophages after T. gondii infection, but it remains unknown whether T. gondii infection can induce dMDSC dysfunction resulting from the change in LILRB4 expression. Methods: LILRB4-deficient (LILRB4−/−) pregnant mice infected with T. gondii with associated adverse pregnancy outcomes, and anti-LILRB4 neutralized antibodies-treated infected human dMDSCs were used in vivo and in vitro experiments, respectively. The aim was to investigate the effect of LILRB4 expression on dMDSC dysfunction induced by T. gondii infection. Results: Toxoplasma gondii infection was observed to reduce STAT3 phosphorylation, resulting in decreased LILRB4 expression on dMDSCs. The levels of the main functional molecules (arginase-1 [Arg-1], interleukin-10 [IL-10]) and main signaling molecules (phosphorylated Src-homology 2 domain-containing protein tyrosine phosphatase [p-SHP2], phosphorylated signal transducer and activator of transcription 6 [p-STAT6]) in dMDSCs were all significantly reduced in human and mouse dMDSCs due to the decrease of LILRB4 expression induced by T. gondii infection. SHP-2 was found to directly bind to STAT6 and STAT6 to bind to the promoter of the Arg-1 and IL-10 genes during T. gondii infection. Conclusions: The downregulation of LILRB4 expression on dMDSCs induced by T. gondii infection could regulate the expression of Arg-1 and IL-10 via the SHP-2/STAT6 pathway, resulting in the dysfunction of dMDSCs, which might contribute to adverse outcomes during pregnancy by T. gondii infection. [ABSTRACT FROM AUTHOR]

Background: Toxoplasma gondii infection during pregnancy can lead to fetal defect(s) or congenital complications. The inhibitory molecule B7-H4 expressed on decidual macrophages (dMφ) plays an important role in maternal–fetal tolerance. However, the effect of B7-H4 on the function of dMφ during T. gondii infection remains unclear. Methods: Changes in B7-H4 expression on dMφ after T. gondii infection were explored both in vivo and in vitro. B7-H4-/- pregnant mice (pregnant mice with B7-H4 gene knockout) and purified primary human dMφ treated with B7-H4 neutralizing antibody were used to explore the role of B7-H4 signaling on regulating the membrane molecules, synthesis of arginine metabolic enzymes and cytokine production by dMφ with T. gondii infection. Also, adoptive transfer of dMφ from wild-type (WT) pregnant mice or B7-H4-/- pregnant mice to infected B7-H4-/- pregnant mice was used to examine the effect of B7-H4 on adverse pregnancy outcomes induced by T. gondii infection. Results: The results illustrated that B7-H4-/- pregnant mice infected by T. gondii had poorer pregnancy outcomes than their wild-type counterparts. The expression of B7-H4 on dMφ significantly decreased after T. gondii infection, which resulted in the polarization of dMφ from the M2 toward the M1 phenotype by changing the expression of membrane molecules (CD80, CD86, CD163, CD206), synthesis of arginine metabolic enzymes (Arg-1, iNOS) and production of cytokines (IL-10, TNF-α) production. Also, we found that the B7-H4 downregulation after T. gondii infection increased iNOS and TNF-α expression mediated through the JAK2/STAT1 signaling pathway. In addition, adoptive transfer of dMφ from a WT pregnant mouse donor rather than from a B7-H4-/- pregnant mouse donor was able to improve adverse pregnancy outcomes induced by T. gondii infection. Conclusions: The results demonstrated that the downregulation of B7-H4 induced by T. gondii infection led to the dysfunction of decidual macrophages and contributed to abnormal pregnancy outcomes. Moreover, adoptive transfer of B7-H4+ dMφ could improve adverse pregnancy outcomes induced by T. gondii infection. [ABSTRACT FROM AUTHOR]

Background: Women in early pregnancy infected by Toxoplasma gondii may have severe adverse pregnancy outcomes, such as spontaneous abortion and fetal malformation. The inhibitory molecule T cell immunoglobulin and mucin domain 3 (Tim-3) is highly expressed on decidual dendritic cells (dDCs) and plays an important role in maintaining immune tolerance. However, whether T. gondii infection can cause dDC dysfunction by influencing the expression of Tim-3 and further participate in adverse pregnancy outcomes is still unclear. Methods: An abnormal pregnancy model in Tim-3-deficient mice and primary human dDCs treated with Tim-3 neutralizing antibodies were used to examine the effect of Tim-3 expression on dDC dysfunction after T. gondii infection. Results: Following T. gondii infection, the expression of Tim-3 on dDCs was downregulated, those of the pro-inflammatory functional molecules CD80, CD86, MHC-II, tumor necrosis factor-α (TNF-α), and interleukin-12 (IL-12) were increased, while those of the tolerant molecules indoleamine 2,3-dioxygenase (IDO) and interleukin-10 (IL-10) were significantly reduced. Tim-3 downregulation by T. gondii infection was closely associated with an increase in proinflammatory molecules and a decrease in tolerant molecules, which further resulted in dDC dysfunction. Moreover, the changes in Tim-3 induced by T. gondii infection further reduced the secretion of the cytokine IL-10 via the SRC-signal transducer and activator of transcription 3 (STAT3) pathway, which ultimately contributed to abnormal pregnancy outcomes. Conclusions: Toxoplasma gondii infection can significantly downregulate the expression of Tim-3 and cause the aberrant expression of functional molecules in dDCs. This leads to dDC dysfunction, which can ultimately contribute to abnormal pregnancy outcomes. Further, the expression of the anti-inflammatory molecule IL-10 was significantly decreased by Tim-3 downregulation, which was mediated by the SRC-STAT3 signaling pathway in dDCs after T. gondii infection. [ABSTRACT FROM AUTHOR]

Background: Primary infection of Toxoplasma gondii can cause serious abnormal pregnancy outcomes such as miscarriage and stillbirth. Inhibitory molecule B7-H4 is abundantly expressed in dendritic cells (DCs) and plays an important role in maintaining immune tolerance. However, the role of B7-H4 in decidual DCs (dDCs) in T. gondii-induced abnormal pregnancy outcomes is not clear. Methods: We established T. gondii-infected abnormal pregnancy model in wild-type (WT) and B7-H4 knockout (B7-H4−/−) pregnant mice in vivo and cultured primary human dDCs in vitro. The abnormal pregnancy outcomes were observed and the expression of B7-H4, functional molecules (CD80, CD86, and MHC-II or HLA-DR), indoleamine 2,3-dioxygenase (IDO), cytokines (IL-10 and IL-12), and signaling molecules JAK2/STAT3 in dDCs was detected by flow cytometry and Western blot. Results: Our results showed that T. gondii infection significantly decreased B7-H4 expression in dDCs. In addition, B7-H4−/− infected pregnant mice showed much more severe abnormal pregnancy outcomes than their counterparts. Importantly, B7-H4−/− infection further regulated the expression of molecules (CD80, CD86, and MHC-II or HLA-DR), enzyme IDO, and cytokines (IL-10 and IL-12) in dDCs. We further discovered that B7-H4−/− infection impairs the JAK2/STAT3 pathway, contributing to dDC dysfunction. Conclusions: Taken together, the results show that reduction of B7-H4 by T. gondii infection significantly modulates the decrease in cytokine IL-10 and enzyme IDO and the increase in cytokine IL-12, contributing to dDC dysfunction. Moreover, the JAK2/STAT3 pathway is involved in the regulation of B7-H4 by T. gondii infection and in the subsequent IDO and cytokine production, which ultimately contributes to abnormal pregnancy outcomes. [ABSTRACT FROM AUTHOR]

Inhibitory receptors and activating receptor expressed on decidual natural killer (dNK) cells are generally believed to be important in abnormal pregnancy outcomes and induced adverse pregnancy. However, if Toxoplasma gondii (T. gondii) infection induced abnormal pregnancy was related to dNK cells changes is not clear. In this study, we used human dNK cells co-cultured with human extravillous cytotrophoblast (EVT) cells following YFP-Toxoplasma gondii (YFP-T. gondii) infection in vitro and established animal pregnant infection model. Levels of inhibitory receptors KIR2DL4 and ILT-2, their ligand HLA-G, and activating receptor NKG2D in human decidua, and NKG2A and its ligand Qa-1 and NKG2D in mice uterine were analyzed by real-time PCR and flow cytometry with levels of NKG2D significantly higher than those of KIR2DL4 and ILT-2 in vitro and in invo. The level of NKG2D was positively correlated with cytotoxic activity of dNK cells in vitro. Numbers of abnormal pregnancies were significantly greater in the infected group than in the control group. This result demonstrated that the increased NKG2D expression and imbalance between inhibitory receptors of dNK cells and HLA-G may contribute to abnormal pregnancy outcomes observed upon maternal infection with T. gondii. [ABSTRACT FROM AUTHOR]

Aims: Toinvestigate the immunoprotective effect of IL-10 on pregnancy in Toxoplasma gondii-infected C57BL/6 mice. Methods: Twenty-four pregnant mice were randomly divided into 3 equal groups, i.e. a control group (CG), an infected group (IG) and an infected group treated with IL-10 (IPTG). Each IPTG and IG mouse was infected with 400 T. gondii trophozoites on gestational day (GD) 8. Each IPTG mouse was injected with 1 μg recombinant mouse IL-10 via a tail vein on GD 10 and 12. The mice were sacrificed on day 7 postinfection. Qa-1 and NKG2A were analyzed in the placenta by flow cytometry and real-time PCR. IL-4, IL-10 and IFN-γ in the placenta supernatant were analyzed by ELISA. Statistical analysis was performed by one-way ANOVA. Results: IPTG mice showed a better mental state, had larger fetuses and placentas with a better blood supply and a lower resorption ratio compared to IG mice. NKG2A and Qa-1 were significantly increased in IPTG mice compared to IG mice (p < 0.05). IL-4 and IL-10 in IPTG placenta supernatant were increased (p < 0.05), but IFN-γ was decreased (p < 0.05) compared to IG placenta supernatant. The ratios of IFN-γ/IL-4 and IFN-γ/IL-10 were decreased in IPTG mice compared to IG mice (p < 0.05, p < 0.05). Conclusion: IL-10 plays an immunoprotective role and improves the pregnancy outcome of T. gondii-infected mice. Copyright © 2011 S. Karger AG, Basel [ABSTRACT FROM AUTHOR]

Citation Zhang H, Hu X, Liu X, Zhang R, Fu Q, Xu X. The Treg/Th17 Imbalance in Toxoplasma gondii-Infected Pregnant Mice. Am J Reprod Immunol 2012; 67: 112-121 Aim To evaluate whether impaired Treg/Th17 balance exists in the pregnant mice infected with Toxoplasma gondii. Method of Study Regulatory T (Treg) and T-helper type 17 (Th17) cells were measured in both placenta and spleens of the pregnant mice infected with and without T. gondii by flow cytometry. The mRNA and protein expression levels of transforming growth factor-β (TGF-β) and interleukin-17A (IL-17A) were analyzed using real-time PCR and enzyme-linked immunosorbent assay (ELISA). The mRNA expression levels of forkhead box P3 (Foxp3), retinoic acid-related orphan receptor γt (RORγt), and IL-6 were also analyzed using real-time PCR. The correlations of the ratio of Treg/Th17 to the mRNA or protein expression level of those factors were analyzed by Spearman's correlation analysis. Data were analyzed by unpaired t-test and paired t-test. Results The proportion of Tregs or Th17 cells in the placenta and spleens of the T. gondii-infected pregnant mice was significantly lower or higher than in those of non-infected mice, respectively. Upregulation of TGF-β and downregulation of IL-17A were found in the placenta of T. gondii-infected pregnant mice. The ratio of Treg to Th17 was significantly lower in the infected mice than that in the non-infected mice ( P < 0.01).The ratio of Treg to Th17 positively or negatively correlated with the protein expression level of TGF-β ( r = 0.6204, P < 0.05) or IL-17A ( r = −0.6296, P < 0.05), respectively. The ratio also positively correlated with the mRNA expression level of Foxp3 ( r = 0.7985, P < 0.01), but negatively correlated with the mRNA expression level of RORγt ( r = −0.6153, P < 0.05), and IL-6 ( r = −0.7492, P < 0.01). Conclusion TheTreg/Th17 imbalance exists in the pregnant mice infected with T. gondii, which is associated with the expression of related cytokine and key transcription factors. This result suggests that the embryo loss caused by this parasite may be associated with a reduced ratio of Treg to Th17 cell number. [ABSTRACT FROM AUTHOR]

Toxoplasma gondii infection during pregnancy can result in adverse pregnancy outcomes. Previously, we have reported that these outcomes are associated with the impaired function of decidual Treg cells; however, the detailed mechanisms involved were unclear. It has been reported that the suppressive capacity of Treg cells is dependent on PD-1 expression. The present study explored the role of decidual PD-1+ Treg cell function in adverse pregnancy outcomes due to T. gondii infection. Toxoplasma gondii–infected pregnant mice were sacrificed on gestational day 14 and their pregnancy outcomes were observed. The expression of PD-1 on decidual Treg cells and expressions of Foxp3, CTLA-4, TGF-β, and IL-10 on decidual PD-1+ and PD-1− Treg cells were determined using flow cytometry. The results showed that the expression of PD-1 on decidual Treg cells was clearly higher in the T. gondii–infected mice than in the normal mice. Meanwhile, the expressions of Foxp3, CTLA-4, TGF-β, and IL-10 on decidual PD-1+ Treg cells were higher in the infected mice than in the normal mice. The expressions were higher in decidual PD1+ Treg cells than in PD-1− Treg cells in the infected mice. However, these expressions on PD-1− Treg cells did not significantly differ between the infected and normal mice. Nonetheless, the absolute percentages of decidual PD-1+ Treg cells decreased significantly in the infected mice compared with those in the normal mice. These results suggest that T. gondii infection mainly influences the function of decidual PD-1+ Treg cells, which would result in an insufficiently immunotolerant microenvironment and consequently in adverse pregnancy outcomes. [ABSTRACT FROM AUTHOR]

A Toxoplasma gondii infection during pregnancy can result in spontaneous abortion, preterm labor, or congenital fetal defects. The decidual immune system plays a critical role in regulating the immune micro-environment and in the induction of immune tolerance. To better understand the factors that mediate the decidual immune response associated with the T. gondii infection, a large-scale study employing TMT proteomics was conducted to characterize the differential decidual immune proteomes from infected and uninfected human decidual immune cells samples. The decidual immune cells from 105 human voluntary abortion tissues were purified, and of the 5510 unique proteins identified, 181 proteins were found to be differentially abundant (>1.2-fold cutoff, p <  0.05) in the T. gondii -infected decidual immune cells. 11 proteins of 181 differentially expressed proteins associated with trophoblast invasion, placental development, intrauterine fetal growth, and immune tolerance were verified using a quantitative real-time polymerase chain reaction and western blotting. This systematic analysis for the proteomics of decidual immune cells identified a broad range of immune factors in human decidual immune cells, shedding a new insight into the decidual immune molecular mechanism for abnormal pregnancy outcomes associated with T. gondii infection. [ABSTRACT FROM AUTHOR]

Our current aim was to investigate whether injection of TGF-β1 played an important role in improving abnormal pregnancy outcomes with T. gondii infection and how the TGF-β1 regulated. Results showed that TGF-β1 exhibited improved pregnancy outcomes induced by T. gondii infection. dNK cytotoxicity was increased with T. gondii infection while decreased with TGF-β1 treatment. dNK cytotoxicity related NKG2D/DAP10 expression, perforin, granzyme, IFN-γ and killer subsets were all increased with T. gondii infection while decreased after TGF-β1 treatment. In addition, anti-TGF-β1 antibodies could aggregate the cytotoxicity of dNK cells and the levels of molecules above. These results indicated that TGF-β1 treatment could improve the abnormal pregnancy outcomes with T. gondii infection by decreasing the cytotoxicity of dNK cells mediated by NKG2D/DAP10 pathway and killer subset. These results suggested that TGF-β1 might be a potential immunoprotective method for the treatment of abnormal pregnancy outcomes following T. gondii infection. [ABSTRACT FROM AUTHOR]

Toxoplasma gondii is a ubiquitous, obligate intracellular parasite capable of crossing the placental barrier and causing spontaneous abortion, preterm labor, or significant disease in the surviving neonate. To better understand molecular mechanisms underlying abnormal pregnancy outcomes caused by T. gondii , placental proteins extracted from T. gondii -infected and -uninfected mice were comparatively analyzed using label-free liquid chromatography–tandem mass spectrometry. Significant difference was observed in the expression of 58 out of 792 proteins in infected placentas ( p < 0.05) compared with that in uninfected placentas. Quantitative real-time polymerase chain reaction, western blotting, and immunohistochemical staining were used to validate the results of the proteomic analysis. Some placental proteins differentially expressed in infected and uninfected mice were found to be associated with several different biological processes of pregnancy, particularly with trophoblast invasion and placental development. The results provide possible novel insights into the molecular mechanisms for abnormal pregnancy outcomes associated with T. gondii infection. Significance In order to further explore the mechanisms of abnormal pregnant outcomes caused by T. gondii infection, we first applied label-free proteomic technology to analyze the differentially expressed host placental proteins with T. gondii infection. The results showed that some differential proteins are associated with trophoblast invasion and placenta development. The findings provide a systemic view of the altered placental proteins and help to declare the molecular mechanisms of abnormal pregnancy outcomes caused by T. gondii infection. [ABSTRACT FROM AUTHOR]

This study aims to investigate whether IL-10 regulate decidual Treg cells apoptosis to reverse the abnormal pregnancy outcomes with Toxoplasma gondii ( T. gondii ) infection. Recombinant mouse IL-10 (rIL-10) treatment and IL-10 deficiency (IL-10 −/− ) abnormal pregnancy animal models with T. gondii infection were established. Apoptosis related molecules cleaved Caspase-3 and Caspase-8 in decidual Treg cells were examined using flow cytometry. The levels of cleaved Caspase-3 and Caspase-8 in decidual Treg cells were up-regulated with T. gondii infection. Compared to infected group, the expressions of cleaved Caspase-3 and Caspase-8 in decidual Treg cells were down-regulated in rIL-10-treated group, while up-regulated in infected IL-10 −/− group. In addition, pregnant outcomes were improved in rIL-10-treated group, while worse in IL-10 −/− group compared to infected group. These findings revealed that IL-10 reduced the decidual Treg cells apoptosis contributing to improving adverse pregnant outcomes following T. gondii infection. [ABSTRACT FROM AUTHOR]

Summary Objective To assess whether interferon gamma (IFN-γ) secreted by decidual natural killer (dNK) cells at the maternal–fetal interface is involved in the apoptosis of trophoblast cells (trophoblasts) following Toxoplasma gondii infection. Methods Human dNK cells were infected with T. gondii and then co-cultured with trophoblasts. The infected co-cultured cells were treated with or without IFN-γ neutralizing antibodies. Uninfected co-cultured cells were used as controls. The level of IFN-γ in the supernatant of co-culture was measured by ELISA and the apoptosis of trophoblasts was analyzed by flow cytometry. The expression of caspase 3 and caspase 8 of trophoblasts cells was determined by Western blotting and real-time RT-PCR. Results The levels of IFN-γ were increased at <24 h following T. gondii infection and were maintained thereafter. Caspase 3, caspase 8, and the apoptosis of trophoblasts co-cultured with dNK cells were increased compared with the control. Meanwhile, IFN-γ, caspase 3, caspase 8, and trophoblast apoptosis were up-regulated upon increased ratios of dNK cells to trophoblasts. Compared to the infected group, the levels of IFN-γ, caspase 3, caspase 8, and trophoblast apoptosis were significantly decreased upon treatment with the IFN-γ neutralizing antibody. IFN-γ levels were correlated positively with the apoptosis of trophoblasts ( r = 0.7163, p < 0.01). Conclusions The levels of IFN-γ secreted by dNK cells at the maternal–fetal interface were closely correlated with the apoptosis of trophoblasts upon T. gondii infection. The apoptosis of trophoblasts induced by the increase in IFN-γ depended on the caspase pathway, which may contribute to the abnormal pregnancy outcomes that occur with T. gondii infection. [ABSTRACT FROM AUTHOR]

Acute infection with Toxoplasma gondii (T. gondii) during pregnancy is associated with adverse outcomes. The mechanisms that cause this phenomenon are not clear. Regulatory T cells (Tregs) are involved in maternal tolerance, and here we observed a decrease in the absolute numbers of CTLA-4+ Tregs and PD-1+ Tregs in spleen and at the fetal-maternal interface in T. gondii-infected mice. Our results suggest that T. gondii induces apoptosis of Tregs. Additionally, we found that the expression of CTLA-4 and PD-1 on Tregs at fetal-maternal interface were higher than on spleen cells from normal pregnant mice. Therefore, we adoptively transferred Tregs from fetal-maternal interface or from spleens of normal pregnant mice into infected pregnant mice. Pregnancy outcomes were improved when Tregs were transferred from the fetal-maternal interface but not from the spleen. The mechanism appears to be through up-regulation of the number of CTLA-4+ Tregs and PD-1+ Tregs and correction of the imbalance between tolerant cytokines (IL-10, TGF-β) and inflammatory cytokines (IFN-γ). Our data indicate that Tregs at fetal-maternal interface express high levels of inhibitory molecules that play a vital immuno-protective role during pregnancy. [ABSTRACT FROM PUBLISHER]

The aim of this study were to demonstrate the effects of Yellow fluorescent protein- Toxoplasma gondii infection on the NK-92 cells co-cultured with BeWo cells in vitro and to verify the implications upon adverse pregnancy outcome. There are four groups including NK-92 cells infected or uninfected with T. gondii, and NK-92 cells co-cultured with BeWo cells in the presence or absent of T. gondii infection. Cells were observed by fluorescence microscope at 12, 24, 36, 48, and 60 h after infection. Levels of inhibitory receptors killer immunoglobulin-like receptor (KIR)2DL4 and ILT-2 expressed on NK-92 cells, and their common ligand HLA-G expressed on BeWo cells were measured by real-time PCR and flow cytometry in all groups. Levels of KIR2DL4, ILT-2 and HLA-G increased at 12, 24, 36, and 48 h, while decreased at 60 h in all T. gondii-infected groups compared with their parallel control groups, respectively. KIR2DL4 and ILT-2 expression in co-culture groups with infection were higher than those in infected NK-92 groups at 12, 24, 36, and 48 h, while there were no significant differences at 60 h. The expression of the two inhibitory receptors was correlated with HLA-G expression in infected co-culture groups. The changes of inhibitory receptors on NK-92 cells and their common ligand HLA-G on BeWo cells with T. gondii infection might contribute to the occurrence of adverse pregnancy outcome. [ABSTRACT FROM AUTHOR]

Objective: To investigate the changes of human decidual natural killer (dNK) cells cocultured with Toxoplasma gondii in vitro and to infer implications on pregnancy. Design: Case-control study. Setting: College and hospital. Patient(s): Decidual tissue was obtained from 85 patients undergoing voluntary abortion during the first trimester of gestation (6–12 weeks). Intervention(s): None. Main Outcome Measure(s): The dNK cells were isolated and infected with YFP-Toxoplasma gondii. Cells were observed by fluorescence and confocal microscopy. The CD56brightCD16−/CD56dimCD16+ dNK ratio, expression of KIR2DL4, ILT-2, and NKG2D on dNK cells were analyzed by flow cytometry and the cytotoxic activity of infected dNK cells were evaluated. Result(s): The CD56dimCD16+/CD56brightCD16− dNK ratio was significantly elevated at 12, 24, and 48 hours after YFP-T. gondii infection. Expression of KIR2DL4, ILT-2, and NKG2D were increased after infection, but NKG2D were significantly higher than those of KIR2DL4 and ILT-2. Both the CD56dimCD16+/CD56brightCD16− dNK ratio and NKG2D expression were correlated with dNK cytotoxic activity. Conclusion(s): Enhanced dNK cytotoxicity due to increased CD16 and NKG2D expression may contribute to abnormal pregnancy outcomes observed with maternal infection with T. gondii. [ABSTRACT FROM AUTHOR]