Activated T Lymphocytes in Pre-Eclampsia

Decidual regulatory T cells in placental pathology and pregnancy complications

Regulatory T cells (Tregs) have been identified as immunomodulatory cells, which induce tolerance. Evidence from numerous recent studies implicates these cells as critical for maternal tolerance to the fetal-derived placenta, proper functioning of which is required for normal gestation and growth and development of the fetus in utero. This review focuses on the recent studies of Tregs at the maternal-fetal interface in pregnancy complications, as well as their identification in specific inflammatory lesions in the placenta.

Specific infiltration pattern of FOXP3+ regulatory T cells in chronic histiocytic intervillositis of unknown etiology

INTRODUCTION

Chronic histiocytic intervillositis of unknown etiology (CIUE) is a rare placental lesion characterized by an intervillous mononuclear inflammatory infiltrate of maternal origin. Although the mechanism and origin of these lesions are currently not understood, they appear to be related to an immune conflict between mother and fetus cells.

AIM

To clarify the inflammatory cell profile and evaluate the T regulatory lymphocyte (Treg) status in CIUE.

MATERIALS AND METHODS

All cases of CIUE that occurred over an 8-year period were analyzed using immunohistochemistry.

RESULTS

The inflammatory profile of CIUE was characterized by a clearly predominant component of histiocytic cells (80% ± 6.9) associated with some T cells (24% ± 5.7). The ratio of CD4+ versus CD8+ T cells was close to 1. This profile differs from infectious disease and chronic histiocytic villitis, the main differential diagnoses of CIUE. As for normal pregnancies most regulatory T cells were localized in the decidua basalis. Nevertheless, their appearance was also noted in the intervillous space. In both the intervillous space and the deciduas the number of Tregs gradually increased from grade 1 to 3.

CONCLUSION

We found that CIUE is associated with an increase in Treg lymphocytes in the decidua basalis and the intervillous space. Contrary to previously published data on human miscarriage, this result appears to be specific to CIUE and would support the hypothesis of an immunopathological disorder for CIUE.

Apoptosis signaling is altered in CD4⁺CD25⁺FoxP3⁺ T regulatory lymphocytes in pre-eclampsia

The aim of our study was to estimate the surface expressions of CD95 (APO-1/Fas) antigen and the intracellular expressions of anti-apoptotic protein Bcl-2 and pro-apoptotic protein Bax in CD4(+)CD25(+)FoxP3(+) T regulatory lymphocytes (Tregs) as well as the percentage of CD8(+)CD28(+) T cytotoxic cells in peripheral blood of patients with pre-eclampsia in comparison with healthy pregnant women in the third trimester of physiological pregnancy. Twenty-four women with pre-eclampsia and 20 normal third trimester pregnant women were included in the study. The lymphocytes were isolated from peripheral blood samples and labeled with monoclonal antibodies. The expressions of surface antigens and intracellular proteins were estimated using flow cytometry. The population of CD4(+)CD25(+)FoxP3(+) Treg cells was significantly lower in peripheral blood of patients with pre-eclampsia when compared to normal third trimester pregnant women. The percentages of CD4(+)CD25(+)FoxP3(+) Treg cells that express Bcl-2 protein were significantly lower in peripheral blood of patients with pre-eclampsia when compared to healthy pregnant women, whereas the percentages of CD4(+)CD25(+)FoxP3(+) Treg cells with the expressions of Bax protein did not differ in both groups. Moreover, the mean fluorescence intensity (MFI) of Bcl-2 protein in CD4(+)CD25(+)FoxP3(+) Treg cells was significantly lower and MFI of Bax protein significantly higher in pre-eclampsia when compared to the control group. The percentage of CD8(+)CD28(+) T cells did not differ in both studied groups but MFI of CD28 antigen on T CD8(+) cells was significantly higher in pre-eclampsia when compared to the control group. The obtained results suggest that the deficit of CD4(+)CD25(+)FoxP3(+) Treg lymphocytes which is observed in pre-eclampsia may be associated with altered apoptosis signaling in Tregs.

The expressions of CD200 and CD200R molecules on myeloid and lymphoid dendritic cells in pre-eclampsia and normal pregnancy

PROBLEM

The purpose of our study was to test the hypothesis that the expressions of CD200 and CD200R tolerance molecules are increased on peripheral blood dendritic cells (DCs) in normal pregnancy and decreased on peripheral blood DCs in pre-eclampsia.

METHOD OF STUDY

Thirty-three patients with pre-eclampsia, 38 normal pregnant women, and 10 healthy non-pregnant women were included in the study. Dendritic cells were isolated from peripheral blood, stained with monoclonal antibodies against blood dendritic cell antigens as well as CD200 and CD200R antigens, and estimated using flow cytometry.

RESULTS

The expressions of CD200 and CD200R molecules on CD1c(+) myeloid and BDCA-2(+) lymphoid DCs in the first trimester of normal pregnancy were significantly higher when compared to the luteal phase of the ovarian cycle. The expressions of CD200 molecule on CD1c(+) myeloid DCs were significantly lower in the third trimester of normal pregnancy when compared to the second trimester. The expressions of CD200R molecule on CD1c(+) myeloid DCs and BDCA-2(+) lymphoid DCs did not differ in pre-eclampsia and healthy third trimester pregnant women. However, the expressions of CD200 molecule on CD1c(+) myeloid and BDCA-2(+) lymphoid DCs were significantly higher in pre-eclampsia when compared to the healthy third trimester pregnant women.

CONCLUSION

The results suggest increased tolerogenic properties of myeloid and lymphoid DCs in normal human pregnancy. Moreover, they suggest a decrease in tolerogenic properties of DCs before delivery. It seems possible that higher expressions of CD200 molecule on CD1c(+) myeloid and BDCA-2(+) lymphoid DCs in pre-eclampsia may constitute the tolerogenic mechanism secondary to the pro-inflammatory response that is observed in this syndrome.

Peripheral CD300a+CD8+ T lymphocytes with a distinct cytotoxic molecular signature increase in pregnant women with chronic chorioamnionitis

PROBLEM

  CD300a is an immunomodulatory molecule of the immunoglobulin receptor superfamily expressed in the leukocytes of myeloid and lymphoid lineages. However, its biological function on CD8+ T lymphocytes remains largely unknown. This study was conducted to assess the biological significance of CD300a expression in T lymphocytes and to determine whether its expression in peripheral T lymphocytes changes in pregnant women presenting with antifetal rejection.

METHODS OF STUDY

Microarray analysis was performed using total RNA isolated from peripheral CD300a+ and CD300a- T lymphocytes. Flow cytometric analysis of the peripheral blood samples of pregnant women and pathologic examination of the placentas were conducted.

RESULTS

  A large number of genes (N = 1245) were differentially expressed between CD300a- and CD300a+ subsets of CD8+ T lymphocytes, which included CCR7, CD244, CX3CR1, GLNY, GZMB, GZMK, IL15, ITGB1, KLRG1, PRF1, and SLAMF7. Gene ontology analysis of differentially expressed genes demonstrated enrichment of biological processes such as immune response, cell death, and signal transduction. CD300a expression in CD8+ T lymphocytes was coupled to a more cytotoxic molecular signature. Of note, the proportion of CD300a+CD8+ T lymphocytes increased in pregnant women with chronic chorioamnionitis (antifetal rejection of the chorioamniotic membranes; P < 0.05).

CONCLUSION

  The findings of this study strongly suggest an increase in systemic T-lymphocyte-mediated cytotoxicity in pregnant women with chronic chorioamnionitis as a manifestation of maternal antifetal rejection.

The predominance of Th17 lymphocytes and decreased number and function of Treg cells in preeclampsia

The aim of this study was to estimate the prevalence of CD3(+)CD4(+) T lymphocytes producing IL-17, IL-2, IFN-γ, and IL-4, plus CD4(+)CD25(+)FoxP3(+) T regulatory (Treg) cells, in peripheral blood of patients with preeclampsia and healthy women in the third trimester of normal pregnancy. Another purpose was to assess the immunosuppressive activity of Treg cells from patients with preeclampsia compared with controls. Thirty-four preeclampsia patients and 27 healthy pregnant women were included. The percentages of CD4(+)CD25(+)FoxP3(+) Treg cells and CD3(+)CD4(+) T lymphocytes with intracellular expressions of cytokines were estimated using monoclonal antibodies and flow cytometry. In vitro functional assays were performed using a Treg Cell Isolation Kit and (3)H-thymidine incorporation assays. The percentage of CD3(+)CD4(+) T lymphocytes producing IL-17A was significantly higher in preeclampsia than in healthy, normotensive pregnant women in the third trimester (p<0.001). The population of CD4(+)CD25(+)FoxP3(+) Treg cells was significantly lower in the study group compared with controls (p<0.05). There was no change in the stimulation index of CD3(+)CD4(+)CD25(-) T lymphocytes from preeclampsia patients without Treg cells and after addition of autologous Treg cells. In normal pregnancy, the stimulation index of CD3(+)CD4(+)CD25(-) T lymphocytes was significantly higher without Treg cells compared with the response after addition of autologous Treg cells (p<0.05). The results suggest up-regulation of the Th17 immune response in preeclampsia. The decreased number and function of Treg cells may be responsible for activating the inflammatory response characteristic of this disorder. In preeclampsia, the predominance of Th17 immunity could act through modulating the Th1/Th2 immune balance.

Regulatory T helper cells in pregnancy and their roles in systemic versus local immune tolerance

PROBLEM

During pregnancy, the maternal immune system needs to adapt in order not to reject the semi-allogenic fetus.

METHOD

In this review, we describe and discuss the role of regulatory T (Treg) cells in fetal tolerance.

RESULTS

Treg cells constitute a T helper lineage that is derived from thymus (natural Treg cells) or is induced in the periphery (induced Treg cells). Treg cells are enriched at the fetal-maternal interface, showing a suppressive phenotype. In contrast, Treg cells are not increased in the circulation of pregnant women, and the suppressive capacity is similar to that in non-pregnant women. However, aberrations in Treg frequencies and functions, both systemically and in the uterus, may be involved in the complications of pregnancy.

CONCLUSION

Treg cells seem to have distinguished roles locally versus systemically, based on their distribution and phenotype.

A balancing act: mechanisms by which the fetus avoids rejection by the maternal immune system

Successful pregnancy requires strict temporal regulation of maternal immune function to accommodate the growing fetus. Early implantation is facilitated by inflammatory processes that ensure adequate vascular remodeling and placental invasion. To prevent rejection of the fetus, this inflammation must be curtailed; reproductive immunologists are discovering that this process is orchestrated by the fetal unit and, in particular, the extravillous trophoblast. Soluble and particulate factors produced by the trophoblast regulate maternal immune cells within the decidua, as well as in the periphery. The aim of this review is to discuss the action of recently discovered immunomodulatory factors and mechanisms, and the potential effects of dysregulation of such mechanisms on the maternal immune response that may result in pregnancy loss or preeclampsia.

Fetus specific T cell modulation during fertilization, implantation and pregnancy

Recently there is an increasing interest in aspects of a more specific immunoregulation during pregnancy. Understanding these mechanism might have a broader application not only for reproductive immunology but also in general for biology and medicine. Especially the induction, already before conception, of feto-specific T cells with a possibly regulatory function gives a biological explanation of local immunotolerance at the maternal fetal interface, supporting the epidemiological evidence of a feto/paternal-specific immuneregulation. Understanding the expression of specific HLA-classes on trophoblast and the crosstalk of these antigens with various cell types, specifically modulated in the decidua, resulting in the secretion of cytokines and (angiogenic) chemokines has given us a more and more detailed understanding of this regulation. This regulation could be induced by fetal cells circulating in the mother (microchimerism) and from the interaction with fetal subcellular fractions as exosomes, but also from paternal antigens present in seminal fluid. Molecular interaction between paternal and fetal antigens and receptors in endometrium and the decidua are discussed. This review highlights besides uNK cells, especially the function of CD4+ and CD8+ T cells with a regulatory function in the context of recurrent miscarriage and pre-eclampsia. Besides HLA, also male-specific minor histocompatibility antigens and the genetic background for these pregnancy complications are discussed.

Lymphocyte calcium influx characteristics and their modulation by Kv1.3 and IKCa1 channel inhibitors in healthy pregnancy and preeclampsia

PROBLEM

Calcium handling of T lymphocytes is altered in healthy pregnancy (HP) and preeclampsia (PE) compared to non-pregnant (non-P) women. We compared the activation-elicited calcium influx in T lymphocytes in HP, PE and non-P women and tested its alteration upon inhibition of Kv1.3 and IKCa1 potassium channels.

METHOD OF STUDY

The alteration of calcium influx was measured in major T-lymphocyte subsets of 9 non-P, HP and PE women with flow cytometry with or without treatment of cells with potassium channel inhibitors.

RESULTS

The elicited calcium response was lower in HP compared to non-P. In HP, calcium influx was sensitive to potassium channel inhibition in CD8 and Th1, but not in Th2 cells. In PE, calcium influx and its sensitivity to inhibition were comparable to non-P.

CONCLUSION

There is a characteristic pattern of calcium influx in T lymphocytes and its sensitivity to potassium channel inhibition in HP that is missing in PE, raising the notion that T-lymphocyte calcium handling may have a role in the characteristic immune status of HP.

SLE and pregnancy: the potential role for regulatory T cells

Systemic lupus erythematosus (SLE) is a multisystem autoimmune disorder that disproportionally affects women, especially in their reproductive years. SLE is associated with considerable pregnancy-related morbidity--including fetal loss, preterm birth, fetal growth restriction and pre-eclampsia. CD4+CD25+ regulatory T (T(REG)) cells have a potent immunosuppressive function and contribute to immunological self-tolerance. These cells might be essential for successful placental development by ensuring fetal tolerance. The numbers of T(REG) cells are augmented during normal pregnancy and, conversely, diminished numbers are associated with pregnancy loss and pre-eclampsia. Several studies have shown that patients with SLE have decreased numbers of T(REG) cells that might be functionally defective. This defective T(REG) cell functioning could predispose women with SLE to pregnancy complications. This article provides an overview of current knowledge of the role and function of T(REG) cells in SLE and pregnancy and how these cells might contribute to improving pregnancy-related outcomes in patients with SLE in the future.

Regulatory T cells are necessary for implantation and maintenance of early pregnancy but not late pregnancy in allogeneic mice

Maternal T cells acquire a transient state of tolerance specific for paternal alloantigens during pregnancy. CD4(+)CD25(+) regulatory T (Treg) cells play a central role in induction and maintenance of tolerance. We have studied the role of Treg cells for the maintenance of allogeneic pregnancy during the implantation period, early pregnancy period and late pregnancy period. We performed depletion of Treg cells using treatment with anti-CD25 monoclonal antibody (mAb) in allogeneic or syngeneic pregnant mice. BALB/c or C57BL/6 female mice were mated with BALB/c or C57BL/6 male mice, and anti-CD25 mAb was injected intraperitoneally on day 2.5 post-coitum (pc), or days 4.5 and 7.5 pc, or days 10.5 and 13.5 pc. Administration of 0.5mg of anti-CD25 mAb induced depletion of CD4(+)CD25(+)Foxp3(+) Treg cells in both allogeneic and syngeneic pregnancy. The extent of depletion of CD4(+)CD25(+) Treg cells in spleen cells was 82.7%. This mAb treatment on day 2.5 pc of pregnancy induced implantation failure in allogeneic pregnant mice, but not in syngeneic pregnant mice. In addition, anti-CD25 mAb treatment on days 4.5 and 7.5 pc significantly increased resorption rates in allogeneic pregnant mice, but not in syngeneic pregnant mice. Interestingly, anti-CD25mAb treatment on days 10.5 and 13.5 pc reduced Treg cell numbers, but this treatment did not induce any abnormal pregnancy parameters such as intrauterine growth restriction, hypertension, or proteinuria. These findings suggest that CD4(+)CD25(+)Foxp3(+) Treg cells are important to mediate maternal tolerance to the allogeneic fetus in the implantation phase and early stage of pregnancy, but Treg cells might not be necessary for maintenance of the late stage of allogeneic pregnancy.

Preeclampsia is associated with lower percentages of regulatory T cells in maternal blood

OBJECTIVE

Immunological mechanisms are involved in the pathophysiology of preeclampsia. During pregnancy there is an increase in regulatory T (Treg) cells, which has an important role in regulating tolerance to the immunologically distinct fetus. We hypothesised that percentages of Treg cells are decreased in preeclamptic patients.

METHODS

Peripheral blood was obtained from 26 healthy pregnant controls and 18 preeclamptic patients. Treg cells were measured using flow-cytometry.

RESULTS

Women with pregnancies complicated by preeclampsia had significantly lower percentages of CD4(+)FOXP3(+) Treg cells.

CONCLUSION

We conclude that a deficiency of regulatory T cells may play a role in the pathophysiology of preeclampsia.

Specific subsets of immune cells in human decidua differ between normal pregnancy and preeclampsia--a prospective observational study

BACKGROUND

Changes in the balance of decidual leucocyte populations may lead to an unfavourable uterine microenvironment which may be associated with the development of preeclampsia (PE). In this study, we therefore investigated the leucocyte subpopulations in decidual tissues of 33 women with preeclampsia and 66 control patients.

METHODS

Decidua was either obtained via curettage during cesarean section or dissected from the surface of the basal plate of the placenta after spontaneous delivery. We used FACS analysis to quantify decidual leukocytes (CD45), NK cells (CD56+/CD16+ and CD56++/CD16-), antigen presenting cells (HLA-DR, DC-Sign, CD14) and T/B cells (CD8, CD4, alpha-beta-T-cell receptor, gamma-delta-T-cell receptor, CD25, CD19).

RESULTS

The number of decidual cytotoxic CD8+T-lymphocytes (P < 0.02), alpha-beta -T-cell receptor positive T cells (P < 0.03) and of CD56+/CD16+ NK cells (P < 0.03) was lower in decidua from women with PE than in decidua from control patients.

CONCLUSION

The observed reduction of specific leucocyte subsets could create a microenvironment which is unfavourable for an appropriate placentation and could thereby be involved in the development of preeclamptic symptoms.

Leukocyte activation and circulating leukocyte-derived microparticles in preeclampsia

PROBLEM

Preeclampsia shows characteristics of an inflammatory disease including leukocyte activation. Analyses of leukocyte-derived microparticles (MP) and mRNA expression of inflammation-related genes in leukocytes may establish which subgroups of leukocytes contribute to the development of preeclampsia.

METHOD OF STUDY

Blood samples were obtained from preeclamptic patients, normotensive pregnant and non-pregnant controls. sL-selectin and elastase were measured by ELISA. mRNA was isolated from leukocytes and gene expression was determined by multiplex ligation-dependent probe amplification (MLPA). MP were characterized by flow cytometry.

RESULTS

Altered concentrations of sL-selectin and elastase confirmed leukocyte activation in preeclampsia. These leukocytes showed up-regulation of Nuclear Factor of Kappa light chain gene enhancer in B cells inhibitor (NFkappaB-1A) and cyclin-dependent kinase inhibitor (CDKN)-1A compared with normotensive pregnant women. Interleukin-1 Receptor Antagonist (IL-1RA) and tumor necrosis factor (TNF)-R1 were increased compared with those in non-pregnant controls. Monocyte-derived MP were elevated in preeclamptic patients compared with pregnant women. The numbers of cytotoxic T-cell-derived and granulocyte-derived MP were elevated compared with those of non-pregnant women.

CONCLUSION

Leukocytes are activated in preeclampsia. A pro-inflammatory gene expression profile is not prominent, although differences in mRNA expression can be detected. Increased levels of particular subsets of leukocyte-derived MP reflect activation of their parental cells in preeclampsia.

Functional changes of human peripheral B-lymphocytes in pre-eclampsia

PROBLEM

The aim of our study was to investigate the functional changes of human peripheral B-lymphocytes in healthy and pre-eclamptic pregnancies.

METHOD OF STUDY

Twenty patients with pre-eclampsia and 15 healthy third-trimester pregnant women were recruited in this study. Peripheral blood mononuclear cells (PBMCs) were isolated and directly stained with fluorescein isothiocyanate (FITC)-labeled anti-CD27 monoclonal antibody (mAb) and phycoerythrin (PE)-labeled anti-CD38 mAb. The percentages of the individual B-cell subsets were estimated out of total lymphocytes by flow cytometric analysis. Additionally, the enriched PBMCs were cultured with or without the stimulation of pokeweed mitogen (PWM) for 5 days. Then morphologic observation of plasma cells was analysed by Wright-Giemsa stain, and antibody-producing cells were detected by enzyme-linked immunospot assay.

RESULTS

The percentage of CD27(-)CD38(-) naïve B-cells and CD27(-)CD38(+) plasma cells did not differ between study groups (P > 0.05). The percentage of CD27(+)CD38(-) memory B-cells and CD27(+)CD38(+) plasma cell precursors increased in pre-eclamptic women compared with the controls (P < 0.05). Irrespective of whether the PBMCs were stimulated with or w/o PWM in vitro, the mean percentages of generated plasma cells were significantly higher in pre-eclamptic group than in the controls (P < 0.05). There were more antibody-producing cells in pre-eclamptic women following the activation of PWM than those in the controls (P < 0.01).

CONCLUSION

Our findings implicate that the functional changes of human circulating B-cells might contribute to the etiology of pre-eclampsia.

Regulatory T-cells and immune tolerance in pregnancy: a new target for infertility treatment?

BACKGROUND

Adaptation of the maternal immune response to accommodate the semi-allogeneic fetus is necessary for pregnancy success, and disturbances in maternal tolerance are implicated in infertility and reproductive pathologies. T regulatory (Treg) cells are a recently discovered subset of T-lymphocytes with potent suppressive activity and pivotal roles in curtailing destructive immune responses and preventing autoimmune disease.

METHODS

A systematic review was undertaken of the published literature on Treg cells in the ovary, testes, uterus and gestational tissues in pregnancy, and their link with infertility, miscarriage and pathologies of pregnancy. An overview of current knowledge on the generation, activation and modes of action of Treg cells in controlling immune responses is provided, and strategies for manipulating regulatory T-cells for potential applications in reproductive medicine are discussed.

RESULTS

Studies in mouse models show that Treg cells are essential for maternal tolerance of the conceptus, and that expansion of the Treg cell pool through antigen-specific and antigen non-specific pathways allows their suppressive actions to be exerted in the critical peri-implantation phase of pregnancy. In women, Treg cells accumulate in the decidua and are elevated in maternal blood from early in the first trimester. Inadequate numbers of Treg cells or their functional deficiency are linked with infertility, miscarriage and pre-eclampsia.

CONCLUSIONS

The potency and wide-ranging involvement of Treg cells in immune homeostasis and disease pathology indicates the considerable potential of these cells as therapeutic agents, raising the prospect of their utility in novel treatments for reproductive pathologies.

Exodus-1 (CCL20): evidence for the participation of this chemokine in spontaneous labor at term, preterm labor, and intrauterine infection

AIM

CCL20, also known as MIP-3 alpha, is a chemokine that participates in chemotaxis of immature dendritic cells, effector/memory T-cells, and B-lymphocytes. The objectives of this study were to determine whether CCL20 can be detected in amniotic fluid (AF) and if AF concentration of this chemokine changes with advancing gestational age, parturition (term and preterm), and intra-amniotic infection/inflammation (IAI).

METHODS

A cross-sectional study was conducted including the following groups: (1) mid-trimester of pregnancy (n=65); (2) term not in labor (TNL; n=22); (3) term in labor (TIL; n=47); (4) spontaneous preterm labor (PTL) who delivered at term (n=57); (5) spontaneous PTL without IAI who delivered preterm (n=71); and (6) spontaneous PTL with IAI (n=38). AF CCL20 concentrations were determined using ELISA.

RESULTS

(1) The median AF CCL20 concentration in TNL was higher than that of mid-trimester patients; (2) Women in spontaneous labor at term had a higher median AF concentration of CCL20 than patients at term not in labor; (3) Patients with spontaneous PTL and IAI had a significantly higher median AF concentration of CCL20 than those without IAI who delivered preterm and those who delivered at term. Moreover, women with spontaneous PTL without IAI who delivered preterm had a significantly higher median AF concentration than those with PTL who subsequently delivered at term.

CONCLUSIONS

(1) CCL20 is a physiologic constituent of AF and its concentration increases as term approaches; (2) spontaneous labor (term and preterm) in the absence of IAI is associated with increased bioavailability of AF CCL20 suggesting that an increase in CCL20 is part of the common pathway of human parturition; (3) patients with IAI had dramatic elevations in the AF CCL20 concentrations suggesting that this chemokine participates in the host response to infection or other stimuli associated with intra-amniotic infection.