Embryonic trophoblasts induce decidual regulatory T cell differentiation and maternal-fetal tolerance through thymic stromal lymphopoietin instructing dendritic cells.

Physiological pregnancy requires the maternal immune system to recognize and tolerate embryonic Ags. Although multiple mechanisms have been proposed, it is not yet clear how the fetus evades the maternal immune system. In this article, we demonstrate that trophoblast-derived thymic stromal lymphopoietin (TSLP) instructs decidual CD11c(+) dendritic cells (dDCs)with increased costimulatory molecules; MHC class II; and Th2/3-type, but not Th1-type, cytokines. TSLP-activated dDCs induce proliferation and differentiation of decidual CD4(+)CD25(-) T cells into CD4(+)CD25(+)FOXP3(+) regulatory T cells (Tregs) through TGF-ß1. TSLP-activated dDC-induced Tregs display immunosuppressive features and express Th2-type cytokines. In addition, decidual CD4(+)CD25(+)FOXP3(+) Tregs promote invasiveness and HLA-G expression of trophoblasts, resulting in preferential production of Th2 cytokines and reduced cytotoxicity in decidual CD56(bright)CD16(-) NK cells. Of interest, decreased TSLP expression and reduced numbers of Tregs were observed at the maternal-fetal interface during miscarriage. Our study identifies a novel feedback loop between embryo-derived trophoblasts and maternal decidual leukocytes, which induces a tolerogenic immune response to ensure a successful pregnancy.

The decidual stromal cells-secreted CCL2 induces and maintains decidual leukocytes into Th2 bias in human early pregnancy.

The precise mechanism of characteristic Th2 predominance at maternal-fetal interface remains unresolved. In the present study, we investigated roles of the decidua-derived CCL2 in Th2 predominance at maternal-fetal interface. FCM shows that 55% CD56(+)CD16(-)CD3(-) decidual NK, 52% CD4(+) T cells and 75% CD14(+) monocytes express CCR2. Recombinant human CCL2 (rhCCL2) and the decidual stromal cells (DSCs)-derived supernatant can enhance proliferation and inhibit apoptosis of these decidual leukocytes (DLCs), and promote Th2 cytokines production, IL-4 and IL-10, with an increase in GATA-3 transcription. They also inhibit the secretion of Th1 cytokines, TNF-α and IFN-γ, with a decrease in T-bet transcription It is concluded that the secreted CCL2 by decidual stromal cells increases GATA-3 transcription and decreases T-bet transcription in the decidual leukocytes, which contributes to Th2 polarization at maternal-fetal interface. Furthermore, the Th2 cytokines, IL-4 and IL-10, rather than Th1 cytokines, was shown to increase CCL2 secretion of DSC.

Thymic stromal lymphopoietin from trophoblasts induces dendritic cell-mediated regulatory TH2 bias in the decidua during early gestation in humans.

Thymic stromal lymphopoietins (TSLPs) play critical roles in dendritic cell-mediated immune responses. In this study, we found that human trophoblasts and decidual epithelial cells in maternal-fetal interface of early placentas express TSLP mRNA and protein, but only trophoblast cells secret soluble TSLP. Human decidual CD1c(+) DCs (dDCs) highly express the functional TSLP receptor complex TSLP receptor and interleukin-7 receptor-α. Recombinant human TSLP activates CD1C(+) decidual DCs and peripheral monocyte-derived DCs with increased costimulatory molecules, major histocompatibility complex class II, and OX-40L. Human TSLP or supernatants from human trophoblasts specifically stimulate dDCs to highly produce interleukin-10 and T(H)2-attracting chemokine CCL-17. The TSLP-activated dDCs prime decidual CD4(+) T cells for T(H)2 cell differentiation, involved in maternal-fetal immunotolerance. Interestingly, the protein expression of TSLP in normal pregnancy with significant T(H)2 bias is much higher than that of miscarriage showing T(H)1 bias at the maternal-fetal interface. Therefore, human trophoblasts may contribute to maternal-fetal tolerance by instructing dDCs to induce regulatory T(H)2 bias in human early pregnancy via TSLP.

Functional regulation of thymic stromal lymphopoietin on proliferation and invasion of trophoblasts in human first-trimester pregnancy.

BACKGROUND: Thymic stromal lymphopoietin (TSLP) is a novel cytokine that triggers the dendritic cell-mediated T(H)2 response and regulatory T cell expansion. The aim of this study is to evaluate whether TSLP and TSLP receptor (TSLPR) are expressed in primary human extravillous trophoblast (EVT), how proimflammatory cytokines (tumor necrosis factor (TNF)-alpha, IL-1beta), T(H)2 and T(H)3 cytokines (IL-4, TGF-beta) and pregnancy-associated hormones regulate TSLP production by EVT and whether the SLP-TSLPR interaction affects the biological behavior of trophoblsts. METHODS: We assessed TSLP mRNA and protein expression by real-time RT-PCR, ELISA and immunochemistry, respectively. We further investigated effects of TSLP on the proliferation and invasion of trophoblast cells in vitro. RESULTS: The primary EVTs constitutively expressed TSLP and TSLPR. IL-4 and TNF-alpha or pregnancy-associated hormones result in a significant increase in TSLP mRNA expression and protein release from EVT, and TSLP promotes primary EVT proliferation and invasion in vitro. CONCLUSIONS: This study has demonstrated that the first-trimester human trophoblast cells express TSLP and TSLPR, that cytokine milieu which mimics the maternal-fetal interface modulates expression of TSLP in trophoblast and that TSLP stimulates trophoblast proliferation and invasion. This suggests that TSLP plays an important role in human EVT invasion and placentation in human early pregnancy.

The CD4+CD25 bright regulatory T cells and CTLA-4 expression in peripheral and decidual lymphocytes are down-regulated in human miscarriage.

The present study was undertaken to analyze the changes in the proportion of CD4(+)CD25(bright) regulatory T (Treg) cells and the expression of costimulatory molecules, CTLA-4 and CD28, in the peripheral blood and deciduas in the setting of non-pregnancy, normal early pregnancy and miscarriage. In this study, we showed that CD4(+)CD25(bright) T cells significantly increased in the peripheral of normal pregnancy compared to that of non-pregnancy. The proportions of CD4(+)CD25(bright) T cells in both peripheral blood and deciduas were significantly lower in miscarriage than that of normal pregnancy. CD4(+)CD25(bright) T cells were characterized by high-level FoxP3 expression and low-level CD69 expression. An increase in the CD28 mRNA expression was accompanied by a decrease in the CTLA-4 mRNA expression in decidual tissues from human miscarriage. The ratios of CTLA-4(+)/CD28(+) in miscarriage were significantly lower than that of the normal pregnancy both in the peripheral and in deciduas. The ratio of CTLA-4(+)/CD28(+) in CD4(+)CD25(bright) T cells was significantly higher than that of the CD4(+)CD25(dim) T cells both in normal pregnancy and in miscarriage. The decidual T cells in the miscarriage appeared higher in responsiveness and IL-2 and IFN-gamma production in comparison with the decidual T cells in the early pregnancy. These results above suggest that CD4(+)CD25(bright) Treg cells might play a role in the maintenance of pregnancy via up-regulation of CTLA-4 expression. The down-regulation of Treg cells and their functions, and the imbalance of positive and negative regulators of costimulatory signals might lead to an abnormal immune milieu, which confer susceptibility to pregnancy loss.

[Genotyping study of hepatitis B virus in its intrauterine transmission].

OBJECTIVE: To study the characteristics of intrauterine transmission of hepatitis B virus (HBV) of different genotypes from mother to the newborn babies. METHODS: One hundred and thirty-five HBsAg-positive pregnant women from 3 hospitals in Guangzhou municipality and their 139 newborn babies were enrolled in this study. Peripheral blood samples were collected from both the mothers before delivery and the neonates within 3 d after birth, and during the follow-up survey, sampling was also performed in some of the newborn babies. Nested-PCR was employed for the amplification of the S region of HBV genome, the product of which was subjected to digestion with restriction endonuclease to compare the restriction fragments length polymorphism (RFLP) to determine the HBV genotype. Direct sequence analysis was conducted and the results compared with the sequences available in Genebank. RESULTS: HBV infection occurred in 7 (5.0%) neonates through intrauterine transmission, among whom 3 were identified as being infected with C genotype, 3 with B genotype and 1 with D genotype, all identical to the genotypes afflicting their mothers. All of the 7 mothers and the babies were asymptomatic. CONCLUSION: C and B genotypes are predominant in intrauterine transmission of HBV in Guangzhou, and base mutation, rather than mutation at the endonuclease digestion site, may take place during intrauterine transmission due to impact of the immune system. The genotyping results, however, can not help make prognostic assessment of the infected babies.

The costimulatory signal upregulation is associated with Th1 bias at the maternal-fetal interface in human miscarriage.

PROBLEM To evaluate whether the association of the costimulatory signal regulation with T helper 1/T helper 2 (Th1/Th2) bias at maternal-fetal interface in human pregnancy loss. METHOD OF STUDY The expression of CD80 and CD86 in decidual tissues and CD28 and cytotoxic T-lymphocyte antigen-4 (CTLA-4) in the decidual T cells was compared between normal early pregnancy and miscarriage by qPCR and Western blot. The cytokine production in decidual T cells was performed by flow cytometry. The correlation of costimulatory molecule expression with Th1/Th2 cytokines was analyzed. RESULTS The CD80 mRNA and protein expression showed no significant difference between normal pregnancy and miscarriage. An increase in the expression of CD28 and CD86 was accompanied by a decrease in the expression of CTLA-4 in miscarriage in comparison with the early pregnancy. The higher expression of interleukin (IL)-2 and interferon-γ (IFN-γ), and lower expression of IL-4 and IL-10 in the decidual T cells were present in miscarriage. A correlation analysis showed a significant positive correlation of CD86 and CD28 expression with the Th1 cytokine production (IL-2 and IFN-γ), a significant negative correlation of CTLA-4 expression with the Th1 cytokine production. CONCLUSION The upregualtion of costimulatory signals on T cells might form an abnormal immune microenvironment, a shift to Th1 responses, at maternal-fetal interface, which leads to human miscarriage.

The regulatory role of thymic stromal lymphopoietin (TSLP) in maternal-fetal immune tolerance during early human pregnancy.

Thymic stromal lymphopoietin (TSLP) is an IL-7-like cytokine, and the functional TSLP receptor (TSLPR) consists of a common IL-7 receptor alpha chain (IL-7Ralpha) and TSLP-specific gamma receptor chain (TSLPR-gamma). It has been demonstrated that TSLP plays an important role in the Th2 bias and regulatory T cell expansion of immune response and tolerance. A successful pregnancy, especially in the early phase, demonstrates features of a Th2 immune response and requires CD4(+)Foxp3(+) regulatory T cell expansion. We have found recently that TSLP-instructed decidual dendritic cells (dDCs) promote decidual CD4(+) T cells to produce Th2-type cytokines including IL-10, which is believed to be a key player in maternal-fetal tolerance. Phenotypic analyses have shown that the expanded cells are mainly CD4(+) Th2 cells and Foxp3(+) regulatory T cells. Our findings show that trophoblasts secrete TSLP that is able to instruct the dDCs to induce CD4(+) Th2 cell and Foxp3(+) regulatory T cell differentiation in decidual CD4(+) T cells.

Regulation of C-C motif chemokine ligand 2 and its receptor in human decidual stromal cells by pregnancy-associated hormones in early gestation.

BACKGROUND: Decidua is in close contact with the fetal trophoblasts, and involved in immune relationship of mother to fetus. However, the roles of decidua and decidual stromal cells (DSC) in materno-fetal immune regulation remain to be elucidated. In the present study, the expression and regulation of chemokines and their receptors in decidua and DSCs were investigated. METHODS AND RESULTS: The transcription of 18 chemokine receptors in human first-trimester decidual tissue and DSC were first analysed by RT-PCR. Among these receptors, C-C motif chemokine receptor-2 (CCR2) was highly transcribed. It was demonstrated by RT-PCR and immunostaining that both CCR2 and its major ligand, C-C motif chemokine ligand 2 (CCL2, monocyte chemoattractant protein-1), were expressed in decidua and DSC. We then detected CCL2 in the supernatant of primary cultures of DSC by enzyme-linked immunosorbent assay. It was shown that DSC secreted CCL2 spontaneously and continuously over 72 h (21.72 +/- 2.34 ng/ml), and the CCR2 antagonist RS102895 and an inhibitor of the map kinase kinase/mitogen-activated protein kinase (ERK/MAPK) signal pathway decreased significantly the CCL2 secretion of DSC (both P < 0.05). We further studied effects of the pregnancy-associated hormones, estrogen, progesterone or HCG on CCL2 secretion by DSC. CCL2 secretion by DSC was up-regulated by estrogen, progesterone or HCG. CONCLUSIONS: CCR2 and CCL2 are co-expressed by human first-trimester DSC and decidual tissue. CCL2 is secreted in an autocrine manner through the ERK/MAPK pathway, and is up-regulated by the pregnancy-associated hormones, estrogen, progesterone and HCG, which suggests that CCL2 may play an important role at materno-fetal interface.