Phenotypic characterization of regulatory T cells in the human decidua

Pregnancy is a unique situation for the maternal immune system. We have studied and identified a CD4+CD25+ regulatory T (Treg) cell population isolated from the human decidua. This mucosal surface in the uterus is in direct contact with semiallogenic fetal cells. We observed that about 14% of the decidual CD4+ T cells have the CD4+CD25+ phenotype. The decidual CD4+CD25+ T cells expressed high frequency of intracellular CTLA-4 (CTLA-4i). The majority of CD4+CD25+CTLA-4i+ cells were also positive for GITR and OX40, typical markers for human Treg cells. The frequency of CD4+CD25+ T cells in the peripheral blood from pregnant women was found to be increased during the first and second trimester of gestation when compared to nonpregnant controls. Being an important molecule for Treg cells, the role of CTLA-4 in the regulation of indoleamine 2,3-dioxygenase (IDO) expression was also examined. The stimulation with CTLA-4Ig did not increase IDO mRNA expression in CD14+ cells from pregnant women, while IFN-gamma was observed to up-regulate IDO expression. The presence of Treg cells in the human decidua suggests that these cells are important in protecting the fetus from alloreactive immune responses at the maternal-fetal interface.     

Neonatal dendritic cells are intrinsically biased against Th-1 immune responses

Dendritic cells (DCs) were derived from human peripheral blood monocytes or cord blood monocytes cultured in the presence of IL-4 and GM-CSF. Adult and cord DCs were observed to have comparable immature phenotypes. However, the increase in surface expression of HLA-DR and CD86 after addition of LPS was significantly attenuated in cord DCs, with CD25 and CD83 expression also markedly reduced. Cord DCs were also unable to produce IL-12p70, failed to down-regulate expression of the chemokine receptor CCR5 and induced lower levels of IFN-gamma production from allogeneic naive CD4+ T cells than their adult counterparts. In contrast, the kinetics of the production of TNF-alpha and IL-10 in response to LPS stimulation was comparable to adult DCs. The reduced ability of cord DCs to attain a fully mature adult phenotype, and to activate naive CD4+ T cells to produce IFN-gamma, suggests that they are intrinsically preprogrammed against the generation of Th-1 immune responses.     

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.     

Proportion of CD56+3+ T cells in decidual and peripheral lymphocytes of normal pregnancy and spontaneous abortion with and without history of recurrent abortion

PROBLEM: The present study investigated the proportion of CD56+3+ T cells in maternal peripheral and decidual lymphocytes in normal pregnancy and spontaneous abortion with and without history of recurrent spontaneous abortion (RSA). METHOD OF STUDY: Maternal peripheral blood and decidua were taken from normal pregnancies and missed abortions with and without RSA. Decidual lymphocytes were prepared from decidual tissue and analyzed by flow cytometry. RESULTS: In normal pregnancy, the percentages of CD56+3+ T cells in decidual lymphocytes did not differ from those in the peripheral blood. However, the proportion of CD56+3+ T cells in decidual CD3+ T cells increased higher than that in the peripheral CD3+ T cells. The percentages of decidual CD56+3+ T cells in missed abortions with and without RSA were lower than those in normal pregnancies. CONCLUSION: CD56+3+ T cells may play a role in the maintenance of pregnancy. The phenomenon, where the proportion of CD56+3+ T cells in decidual lymphocytes decreases, may be due to an immunologic event leading to missed abortion.     

Impaired dendritic cell differentiation and maturation in the absence of C3

Human monocytes can be differentiated into immature dendritic cells (DCs) in the presence of serum and cytokines. One of the main functions of immature DCs is to capture and process antigens. Following maturation, they differentiate into antigen presenting cells. The role of complement in the differentiation process from monocytes towards immature DCs remains elusive. Here we demonstrate that complement 3 (C3) has a regulatory impact on the expression of specific DC surface molecules and DC-derived cytokine production during DC differentiation. We isolated human adherent peripheral blood mononuclear cells, which were cultured in the presence of GM-CSF plus IL-4 in medium supplemented with normal human serum or C3 deficient serum. The lack of C3 during DC differentiation negatively impacted the expression of C-type lectin receptor DC-SIGN, the antigen presenting molecules HLA-DR and CD1a, and the costimulatory molecules CD80 and CD86. Further, the spontaneous production of IL-6 and IL-12 was reduced in the absence of C3. Moreover, the maturation of immature DCs in response to LPS challenge was impaired in the absence of C3 as evidenced by reduced MHC-II, co-stimulatory molecule expression as well as modulated IL-12 and TNF-alpha production. Collectively, our results provide evidence for a novel role of C3 as a critical cofactor in human DC differentiation and maturation.     

Predominance of Th2-promoting dendritic cells in early human pregnancy decidua

Dendritic cells (DCs) are specialized antigen-presenting cells required for the priming and activation of T cells and promote the differentiation of na?ve CD4+ T cells toward the T helper cell type 1 (Th1) or Th2 phenotype. Here, we describe the characterization of CD45+CD3-CD14-CD16-CD19-CD20-CD56-HLA-DRbright DCs from early human pregnancy decidua by flow cytometry. The percentage of DCs to mononuclear cells (leukocytes) in the decidua was significantly higher than that in the peripheral blood. Moreover, decidual DCs expressed costimulatory molecules such as CD80 and CD86 and a mature marker such as CD83 on their surface. The percentage of CD11c+CD123- myeloid DCs in the decidua was significantly higher than that in the peripheral blood. Conversely, the ratio of CD11c-CD123+ lymphoid DCs in the decidua was significantly lower than that in the peripheral blood. The number of interleukin (IL)-12-producing cells in the total DC population and the myeloid DCs in the decidua was significantly lower than that in the peripheral blood. IL-12 secretion by activated decidual myeloid DCs was significantly lower than that by peripheral DCs. Na?ve CD4+ T cells primed with decidual myeloid DCs led to a higher percentage of Th2 cells in comparison with that with peripheral myeloid DCs. This finding was abolished by exogenous IL-12 administration with decidual myeloid DCs. Thus, the DCs in the decidua could regulate the Th1/Th2 balance to maintain a Th2-dominant state, leading to maintenance of pregnancy.     

Abnormal T-cell reactivity against paternal antigens in spontaneous abortion: adoptive transfer of pregnancy-induced CD4+CD25+ T regulatory cells prevents fetal rejection in a murine abortion model

Mammalian pregnancy is thought to be a state of immunological tolerance. The mechanisms underlying this phenomenon are still poorly understood. Here, we determined whether an inappropriate function of T regulatory (Treg) cells is involved in the pathogenesis of spontaneous abortion. We evaluated spleen and decidual lymphocytes from CBA/J mice undergoing immunological abortion (DBA/2J-mated) or having normal pregnancy (BALB/c-mated) on day 14 of gestation for ex vivo cytokine production after PMA or paternal antigen (alloantigen) stimulation. Treg activity was characterized by quantifying CD4(+)CD25(+) cells, foxp3 expression, and interleukin-10 secretion. Decidual lymphocytes from abortion CBA/J mice contained a significantly higher frequency of interferon-gamma-producing T cells specific for paternal antigens compared to those from normal pregnancy (7.8% versus 2.7%, P < 0.05). Compared to virgin CBA/J females, normal pregnant mice showed strongly elevated numbers of CD4(+)CD25(+) and interleukin-10(+) Treg cells in the thymus whereas significantly lower frequencies of Treg cells were observed in abortion mice. Very interestingly, CD4(+)CD25(+) Treg cells from normal pregnant and nonpregnant CBA/J mice could inhibit both proliferation and interferon-gamma secretion of lymphocytes from abortion mice in vitro whereas in vivo prevention of fetal rejection could only be achieved after adoptive transfer of Treg cells from normal pregnant mice. Our data suggest that pregnancy-induced Treg cells play a vital role in maternal tolerance to the allogeneic fetus.     

香加皮羽扇豆烷乙酸酯(CPLA)对树突状细胞分化成熟的影响

目的：探讨香加皮羽扇豆烷乙酸酯（CPLA）对人外周血单个核细胞（PBMC）来源的树突状细胞（DC）在体外分化成熟及免疫活性的影响。方法：从人外周血分离单个核细胞，与细胞因子GM—CSF、IL-4共培养，于第5天加入DC的促成熟刺激剂TNF-α（阳性对照组）或CPLA。倒置显微镜和透射电镜下观察DC的形态；应用流式细胞术检测成熟DC的表面标志CD1a、CD83、CD80和CD86的表达情况；用ELISA检测DC培养上清中IL-12和IFN-γ的含量；用MTT法测定DC刺激T细胞增殖的能力。结果：培养10d后，经CPLA刺激的PBMC呈现出典型DC的形态学特征；成熟DC的特征性表面分子CD1a、CD83、CD80和CD86表达水平均明显上调（P〈0．05）；细胞培养上清中IL-12和IFN-γ含量明显增高（P〈0．05）；刺激T细胞增殖的能力明显增强（P〈0．05）。结论：CPLA可诱导PBMC来源的DC分化成熟，并可促进其细胞因子的分泌，增强DC的免疫调节活性。     

Cytokine secretion patterns of NK cells and macrophages in early human pregnancy decidua and blood: implications for suppressor macrophages in decidua

PROBLEM: Local immune modulation has been shown to be of considerable importance for the maintenance of successful pregnancy. We have previously reported the secretion of interferon-gamma (IFN-gamma), interleukin-4 (IL-4) and IL-10 in human decidua from early normal pregnancy. The aim of this study was to investigate the cellular source of cytokine secretion in the decidua, and compare this to secretion patterns in peripheral blood. METHOD OF STUDY: Decidual tissue and peripheral blood was collected from 20 women undergoing surgical abortion during first trimester pregnancy. Monocytes/macrophages and NK cells were enriched by immunomagnetic cell separation and cytokine secretion was detected by enzyme-linked immunosorbent spot-forming cell assay. RESULTS: Decidual and peripheral monocytes/macrophages and NK cells spontaneously secrete IFN-gamma, IL-4 and IL-10. The number of IL-10 secreting cells was significantly higher in decidual macrophages compared with decidual non-monocytic cells as well as compared with blood monocytes/macrophages. These differences were not seen for IFN-gamma or IL-4. CONCLUSIONS: Our results indicate that decidual macrophages subserve important suppressive functions in the pregnant uterus.     

早孕期外周血及蜕膜淋巴细胞CD28/CTLA-4的表达

目的：探讨人早孕期外周血及蜕膜淋巴细胞协同刺激分子表达水平在母．胎免疫调节中的作用。方法：以15例正常育龄妇女黄体期外周血为对照，应用流式细胞仪分析15例正常人早孕期外周血及蜕膜淋巴细胞CD28和CTLA-4的表达水平。结果：各组淋巴细胞几乎不表达表面CTLA-4分子；而表达细胞内CTLA-4分子（CTLA-4i）。蜕膜组织淋巴细胞CTLA-4i^＋／CD28^＋的比例显著高于早孕期及黄体期外周血。早孕期与黄体期外周CTLA-4i^＋／CD28^＋的百分率比较无显著性差异。结论：母胎界面局部高表达细胞内CTLA-4在母-胎免疫耐受中起重要作用。     

Decidual and peripheral blood CD4+CD25+ regulatory T cells in early pregnancy subjects and spontaneous abortion cases

Human pregnancy represents a situation of semiallograft to maternal host. Therefore, it has been reported that tolerance to the fetal allograft represents a mechanism for maintaining a pregnancy. CD4(+)CD25(bright) regulatory T cells are known to play an important role in the development and maintenance of tolerance in peripheral tissues. However, the potential role of CD4(+)CD25(bright) T cells in maintaining human pregnancy has not been reported. In this study, we show that early human pregnancy decidua contains an abundance of CD4(+)CD25(bright) T cells, which express CD152(CTLA-4) at a high level. CD4(+)CD25(bright) T cells mediate potent inhibition of autologous T-cell proliferation by anti-CD3 stimulation. Furthermore, these cells inhibit the proliferation of autologous CD4(+)CD25(-) T cells in a dose-dependent fashion. This suppressive function of decidual CD4(+)CD25(+) T cells required cell-to-cell contact. The proportion of decidual CD4(+)CD25(bright) T cells was significantly lower in specimens from spontaneous abortion compared to those from specimens from induced abortions. These results suggest that decidual CD4(+)CD25(bright) T cells contribute to the mechanisms mediating maternal immune tolerance of conceptus antigens and therefore might contribute to the maintenance of pregnancy.     

The effect of human placenta cytotrophoblast cells on the maturation and T cell stimulating ability of dendritic cells in vitro

The success of pregnancy depends upon regulatory mechanisms that allow the fetus to survive and develop to term in the uterus, despite maternal immune cells' awareness of paternal alloantigens. At least some of these specific mechanisms are mediated by the effect of fetal trophoblast cells. In the present study we examine the effect of human placental cytotrophoblast cells (CTCs) on the maturation of dendritic cells (DCs) in vitro. For that purpose, CTCs were isolated from samples of placentae at 5–11 weeks of gestation and co‐cultured with peripheral blood monocytes under conditions inducing DC maturation. CTC were shown to alter the morphology, phenotype and functional properties of DCs. As a result, a significant portion of cells acquire fibroblast‐like morphology and some of the cells retain the expression of CD14. DCs matured in the presence of CTCs do not differ from usual DCs in terms of CD80, CD83 and CD86 expression, as well as the ability to induce allogenic lymphocytes proliferation. However, CTCs reduce significantly the ability of DCs to stimulate interferon‐γ production and the loss of CD62L by T cells. The results obtained indicate that DCs may be involved in pregnancy‐associated changes of cytokine production and T cell migration.     

自然流产中外周血和蜕膜组织自然杀伤细胞亚群的比例变化

目的和方法:采用流式细胞仪检测淋巴细胞亚群法探讨自然流产与正常早孕之间外周血和蜕膜自然杀伤细胞亚群的差异。结果:外周血中自然流产组的CD56⁺的百分率较早孕组有减少的趋势,而CD56⁺CD16⁺的百分率则较早孕组显著减少,CD16⁺的百分率两组间无差异。自然流产组的蜕膜CD56⁺、CD56⁺CD16⁺、CD16⁺的百分率均明显低于早孕组。结论:蜕膜中CD56⁺NK细胞的减少可能是自然流产的原因之一,外周血中CD56⁺和CD56⁺CD16⁺NK细胞的丢失可能对自然流产的发生具有诊断价值。     

Cytotoxic T lymphocyte antigen-4-dependent down-modulation of costimulatory molecules on dendritic cells in CD4+ CD25+ regulatory T-cell-mediated suppression

We have previously demonstrated that CD4+ CD25+ natural regulatory T cells (Treg cells) induce down-modulation of CD80 and CD86 (B7) molecules on dendritic cells (DCs) in vitro. In this report we show that the extent of down-modulation is functionally significant because Treg-cell conditioned DCs induced poor T-cell proliferation responses. Further, we report that down-modulation was induced rapidly and was inhibited by blocking cytotoxic T lymphocyte antigen-4 (CTLA-4), which is constitutively expressed by the Treg cells. Even though Treg cells have previously been reported to kill antigen-presenting cells, the down-modulation was not due to selective killing of DCs expressing high level of the costimulatory molecules. We propose that Treg cells down-modulate B7-molecules on DCs in a CTLA-4-dependent way, thereby enhancing suppression of T-cell activity.     

Dendritic cells modulated by innate immunity improve collagen-induced arthritis and induce regulatory T cells in vivo

Dendritic cells (DCs) mediate interactions between innate and specific immunity and may induce regulatory mechanisms. We investigated the effects of modulated DCs in mice with collagen-induced arthritis (CIA) and tested the responses of cells to induced naturally occurring regulatory T cells. DCs were stimulated or not with DNA or lipopolysaccharide (LPS) for 24 hr. DC maturation was assayed, and then modulated DCs were intraperitoneally injected on day 14 into DBA/1 mice to treat CIA. In addition to arthritis scores and type 2 collagen (CII) response, the induction of CD4(+) CD25(+) T cells was analysed by flow cytometry in peripheral blood and the expression of Foxp3, transforming growth factor (TGF)-beta, interleukin (IL)-10 and cytotoxic T-lymphocyte antigen (CTLA)-4 was quantified. Finally, the expression of indoleamine-2,3-dioxygenase (IDO) was assayed in DCs. In comparison with LPS-stimulated DCs, plasmid-stimulated DCs expressed lower levels of major histocompatibility complex (MHC) class II, CD40, CD80 and CD86 molecules and secreted less IL-12p70, interferon (IFN)-gamma, IL-10 and TNF-alpha, displaying a semi-mature phenotype. Compared with non-stimulated DCs, stimulated DCs improved arthritis scores when injected after immunization, without modifying the T helper type 1 (Th1)/Th2 balance of the immune response against collagen. Stimulated DCs induced markers for regulatory T cells (Foxp3, TGF-beta1 and CTLA-4) in vivo. Only LPS-stimulated DCs expressed IDO, which may explain their better therapeutic efficacy. Regulatory mechanisms were induced using DCs modulated by innate immunity stimulators. Innate immunity mechanisms do not require the presence of the disease-causing antigen, even in T- and B-cell specific diseases. Our results have implications for the treatment of rheumatoid arthritis, an autoimmune disease whose triggering antigen has not been identified, and substantially clarify the role of regulatory T cells in CIA.     

Epstein–Barr virus induces the differentiation of semi-mature dendritic cells from cord blood monocytes

Background

Epstein–Barr virus (EBV) is a tumorigenic virus which has effectively infected nearly all human beings with over 95% adult being seropositive. The persistence of latent EBV infection is not fully understood. Recent studies point towards a hypothesis of immune suppression and immune evasion involving regulatory T cells (Tregs) and dendritic cells (DCs). We sought to explore the mechanism of EBV suppression and immune evasion.

Methods

We compared the effects of EBV on cord blood (CB) and adult DCs differentiation and maturation including phenotype by flow cytometry, cytokine by ELISA and RT-PCR. And we evaluated the function of DC by co-culture DC and Treg by detection the expression of Foxp3, the phenotype and the cytokine profile of Tregs by flow cytometry.

Results

CB DCs derived from EBV-infected CB monocytes or from EBV-infected CB immature DCs (iDCs) displayed distinct phenotypes of “semi-mature” DCs with high expression of co-stimulatory molecules, such as CD40, CD80 and CD86 but low cytokine production, related to immune tolerance and homeostasis. While the EBV-infected adult iDCs resemble that of “pathogen-driven regulatory mature DCs” with high expression of co-stimulatory molecules, down-regulation of IL-12 secretion and up-regulation of IL-10 secretion, related to protection of host and immune evasion of pathogens. EBV infected cord blood monocytes-derived DCs drived Tregs development by driving the expression of Foxp3, increasing the expression of CTLA-4, decreasing the expression of GITR and promoted the generation of intracellular IL-2 and IL-10 by Tregs.

Conclusion

Epstein–Barr virus induces the differentiation of semi-mature dendritic cells from cord blood monocytes. The differences between CB and adult DCs suggested that the developmental maturity of the cells may affect their immune responses to EBV infection.     

母胎界面树突状细胞CCL17和CCL22表达在母胎免疫耐受中的作用

目的: 检测非孕期子宫内膜和正常妊娠早期及复发性自然流产患者蜕膜中树突状细胞(DC)CCL17和CCL22的表达差异,探讨母胎界面DC在CD4⁺CD25⁺调节性T细胞(Treg)的募集及母胎免疫耐受微环境形成中的作用。方法: 正常早孕组人工流产时、复发性流产组清宫时取其蜕膜,正常未孕组行子宫切除时取其内膜组织。分离蜕膜或子宫内膜单个核细胞,体外诱导培养DC,用real-time PCR法分析3组DC CCL17和CCL22 mRNA的表达水平,ELISA法检测3组DC培养上清液中CCL17和CCL22蛋白的表达。结果: 正常早孕组蜕膜DC CCL17和CCL22 mRNA的表达分别为3.04±0.40和1.83±0.24,均高于正常未孕组(0.85±0.24和0.31±0.08,P<0.01)和复发性流产组(1.65±0.14和0.96±0.09,P<0.01)。正常早孕组蜕膜DC能够持续旺盛分泌趋化因子CCL17和CCL22,在培养的12~96 h内CCL17和CCL22的分泌量逐渐增多。同一时点早孕组DC分泌的CCL17和CCL22均明显高于未孕组和复发性流产组DC分泌的CCL17和CCL22(P<0.01)。结论: 正常妊娠后蜕膜DC表达CCL17和CCL22增强,DC可能通过高表达CCL17和CCL22而增强对CD4⁺CD25⁺Treg的趋化作用,从而在母胎界面的免疫耐受中发挥重要作用,蜕膜DC表达CCL17和CCL22下降可能与复发性自然流产的发病有关。     

Deficiency of decidual IL-10 in first trimester missed abortion: a lack of correlation with the decidual immune cell profile

PROBLEM: To determine if first trimester missed abortion decidua is characterized by an altered immune cell profile and/or a modified interleukin (IL)-10 and interferon (IFN)-gamma production pattern compared with decidua from elective termination. METHOD OF STUDY: Flow cytometry and immunohistochemistry techniques were used to determine the decidual immune cell phenotypic profile and production pattern of IL-10 and IFN-gamma in cases of elective termination (n = 14) and missed abortion (n = 12). RESULTS: Both groups had a similar proportion of CD56+ CD16-, CD56+ CD16+, CD19+, CD3+, CD4+, CD8+, alphabeta T cells and gammadelta T cells. The majority of alphabeta and gammadelta positive T cells in both groups coexpressed the natural killer (NK) cell marker CD56, but lacked cell surface expression of CD3. Diminished decidual IL-10 staining was noted in 7/10 missed abortion cases compared with none of the elective termination cases (n = 12) (P = 0.007). A uniform decidual IFN-gamma staining pattern was observed in both groups. CONCLUSION: Decreased IL-10 production coupled with a sustained IFN-gamma presence noted in missed abortion compared with elective termination cases suggest that these cytokines may be important determinants in pregnancy outcome. In contrast, differences in the proportion of immune cells between both groups may not be a critical factor in early pregnancy loss. In normal pregnancy, decidual alphabeta and gammadelta positive T cells with reduced CD3 on their cell surface may be intrinsically restricted in T-cell receptor (TCR)-mediated activation.