Why did your mother reject you? Immunogenetic determinants of the response to environmental selective pressure expressed at the uterine level

Tolerance signaling molecules and pregnancy: IDO, galectins, and the renaissance of regulatory T cells

PROBLEM

Is the concept of maternal tolerance preventing rejection of the semi-allogeneic 'fetal allograft' still valid?

METHOD OF STUDY

Compilation of expert reviews of literature and recent advances in research on indoleamine-2,3 dioxygenase (IDO), regulatory T cells and galectin-1.

RESULTS AND CONCLUSION

A role for IDO in pregnancy success remains speculative, but solid data exist to support a role for Treg cells, and for galectin-1 in induction and action of Treg cells. Just as several signals may need to be simultaneously present to induce Th1 cytokine-triggered abortions, more than 1 signal may need to be simultaneously present to prevent rejection and ensure success. Both complement and coagulation pathways appear necessary for embryo execution.

Dendritic cells: key to fetal tolerance?

Pregnancy is a unique event in which a fetus, despite being genetically and immunologically different from the mother (a hemi-allograft), develops in the uterus. Successful pregnancy implies avoidance of rejection by the maternal immune system. Fetal and maternal immune cells come into direct contact at the decidua, which is a highly specialized mucous membrane that plays a key role in fetal tolerance. Uterine dendritic cells (DC) within the decidua have been implicated in pregnancy maintenance. DC serve as antigen-presenting cells with the unique ability to induce primary immune responses. Just as lymphocytes comprise different subsets, DC subsets have been identified that differentially control lymphocyte function. DC may also act to induce immunologic tolerance and regulation of T cell-mediated immunity. Current understanding of DC immunobiology within the context of mammalian fetal-maternal tolerance is reviewed and discussed herein.

Decreased expression of CD25 on decidual activated T lymphocytes is not mediated by reduced CD25 messenger ribonucleic acid

OBJECTIVE

To clarify whether the down-regulation of CD25 on decidual T cells occurred at the activated T cells and was governed through reduced CD25 messenger RNA (mRNA) production.

DESIGN

Retrospective analysis and prospective study.

SETTING

University hospital and medical college.

PATIENT(S)

A total of 12 women receiving hysterectomies and 20 pregnant women having elective abortions were included.

INTERVENTION(S)

The amount of CD25 mRNA in isolated T cells from peripheral blood, endometrium, and decidua was analyzed with real-time polymerase chain reaction and was compared after coculture with autologous cytotrophoblast cells.

MAIN OUTCOME MEASURE(S)

Expression levels of CD25 and CD25 mRNA before and after coculture.

RESULT(S)

The percentage of activated T cells expressing CD25 is lower in decidua than in peripheral blood but the opposite in regulatory T cells. Nevertheless, the amount of CD25 mRNA in decidual T cells did not decrease, instead of approaching that in corresponding fully activated T cells. In the coculture model, we found that the cytotrophoblast cells could induce the decreased expression of CD25 on T lymphocytes. However, there was no change in the amount of CD25 mRNA in T cells after coculture.

CONCLUSION(S)

This study demonstrates the effectiveness of the coculture model to study fetomaternal interactions and provides evidence that fetal cells may contribute to the control of maternal local immunity and that the decreased expression of CD25 on decidual T lymphocytes is not through the reduced CD25 mRNA level.

Psychosocial maternal stress during pregnancy affects serum corticosterone, blood immune parameters and anxiety behaviour in adult male rat offspring

Exposure to prenatal stress can impair the behavioural and hormonal development in mammals. However, the consequences for the immune system are rarely investigated and there is only limited evidence that naturalistic prenatal stressors do also have the potential to affect the offspring. Thus, by using a social conflict model in female Long-Evans rats, we investigated the effects of prenatal social stress on several behavioural, hormonal and immunological parameters. Offspring from stressed and non-stressed pregnant females were housed in pairs after weaning, and tested at an age of 4-6 months. Prenatally stressed (PS) males were more active in the elevated plus-maze test as indicated by significantly more frequent entries into the open arms compared to prenatal control males (PC). In addition, PS males had significantly lower serum corticosterone concentrations under basal conditions as well as after ACTH-challenge. The basal number of total leukocytes was significantly lower in the PS group due to significantly lower lymphocyte counts. In particular, the CD4+ T-helper cell subset was affected. The lymphocyte proliferation to pokeweed mitogen was lower in PS males. Because some of the present findings do not correspond to previous studies using conventional stressors, we assume that the nature of the stressor plays an important role for pregnancy outcome and behaviour and physiology of the offspring in later life.

Effects of urinary and recombinant gonadotrophins on gene expression profiles during the murine peri-implantation period

BACKGROUND

Controlled ovarian stimulation (COS) with urinary gonadotrophins but not recombinant gonadotrophins, adversely affect the implantation process. In this study, we investigated the effects of urinary and recombinant gonadotrophins on gene expression profiles at implantation sites during the mouse peri-implantation period and the possible molecular mechanisms involved in the detrimental effects of urinary gonadotrophins using microarray technology.

METHODS

Adult female CD1 mice were treated with (i) urinary human FSH (hFSH) and urinary HCG, (ii) recombinant hFSH and recombinant human LH or (iii) saline. Gene expression profiling with GeneChip mouse genome 430 2.0 arrays, containing 45 101 probe sets, was performed using implantation sites on embryonic day 5. Data were statistically analysed using Significance Analysis of Microarrays. Ten genes from the microarray analysis were selected for validation using quantitative RT-PCR (qRT-PCR). A parallel group of pregnant mice was allowed to give birth to study the effect of gonadotrophins on resorption.

RESULTS

Urinary gonadotrophins differentially up-regulated the expression of 30 genes, increased resorption and reduced litter size, whereas recombinant gonadotrophins did not. Nine of the 10 genes were confirmed by qRT-PCR.

CONCLUSIONS

Urinary gonadotrophins, but not recombinant gonadotrophins, exerted differential effects on gene expression during the murine peri-implantation period. These findings might contribute to improve protocols for COS, leading to higher successful pregnancy rates.

Adoptive Transfer of Paternal Antigen-Hyporesponsive T Cells Facilitates a Th2 Bias in Peripheral Lymphocytes and at Materno-Fetal Interface in Murine Abortion-prone Matings

PROBLEM

To investigate the Th1/Th2 cytokine changes in abortion-prone recipient mice adoptively transferred by the paternal antigen-hyporesponsive T cells.

METHOD OF STUDY

The paternal antigen-hyporesponsive T cells were generated by the anti-B7 monoclonal antibody (mAb) treatment and adoptively transferred into pregnant CBA/J mice of abortion-prone matings on day 4 of gestation. The intracellular expressions of Th1 cell-derived cytokine, tumor necrosis factor-alpha, gamma-interferon and interleukin-2 (IL-2) and Th2 cell-derived cytokine, IL-4 and IL-10 in the maternal spleen were analyzed by flow cytometry, and secretions of the Th1 and Th2 cytokines in supernatant of the feto-placental unit culture were analyzed by an enzyme-linked immunosorbent assay.

RESULTS

Our findings showed the increased secretion of Th1 cytokines and the decreased secretion of Th2 cytokines in abortion-prone matings. Treatment with anti-B7 mAbs on day 4 of gestation enhanced Th2 and reduced Th1 cytokine production in abortion-prone matings. Similarly, adoptive transfer of paternal antigen-hyporesponsive T cells induced maternal tolerance to the fetus and displayed a Th2 bias both in the peripheral lymphocytes and at the materno-fetal interface of the abortion-prone matings.

CONCLUSIONS

These findings indicate that the Th2 cytokine bias and an increase in fetal viability induced by the anti-B7 mAb treatment can be transferred to other pregnant mice of the abortion-prone matings.

Toll-like receptor 4 polymorphisms and idiopathic chromosomally normal miscarriage

BACKGROUND

Lipopolysaccharide (LPS or endotoxin) exposure resulting from microbial invasion of the endometrium disturbs the Th1/Th2 balance at the feto-maternal interface and has been linked to the risk of idiopathic miscarriage in a range of human and animal studies. Toll-like receptor 4 (TLR4) mediates LPS signalling, and the human TLR4 gene harbours two single-nucleotide polymorphisms (SNPs) known to reduce LPS responsiveness. We hypothesized that genetic variation altering TLR4 function may influence the risk of idiopathic pregnancy loss.

METHODS AND RESULTS

We examined fetal TLR4 genotypes in a case-control cohort of chromosomally normal miscarriages (n=96) and healthy term newborns (n=113). The allele frequencies of the Asp299Gly and Thr399Ile TLR4 SNPs were determined by quantitative PCR using DNA extracted from extraembryonic tissues and umbilical cord blood, respectively. TLR4 genotype frequencies were not significantly different between cases and controls.

CONCLUSIONS

There was no association between fetal TLR4 polymorphisms, Asp299Gly and Thr399Ile, known to blunt LPS responsiveness, and the risk of idiopathic, chromosomally normal miscarriage. Nevertheless, TLR4 or perhaps other LPS-binding chaperone molecules are biologically plausible candidate genes that may alter the risk of idiopathic miscarriage.

Poly I-C induces early embryo loss in f344 rats: a potential role for NK cells

PROBLEM

Natural killer (NK) cells were associated with first trimester embryo loss. The current study in the inbred F344 rat assessed the role of NK cells in mediating resorptions caused by poly I-C, a non-specific immunostimulator.

METHOD OF STUDY

On fifth day of gestation, rats were injected intraperitoneally with anti-NKR-P1 (1.5 mg/kg, i.p.) to deplete NK cells, and with mouse serum or saline to control for non-specific effects. Poly I-C (4 mg/kg, i.p.) or vehicle were administered 2 days later. Resorptions were assessed on day 13.5.

RESULTS

Poly I-C significantly elevated resorption rates, and anti-NKR-P1 abolished this effect. Body weight was reduced in all rats treated with poly I-C, including NK-depleted rats. This indicates the ability of NK-depleted rats to respond to poly I-C, yet to refrain from the resorption-promoting effects of poly I-C.

CONCLUSIONS

This study suggests a role for NK cells in mediating poly I-C-induced resorptions.

Tumour necrosis factor-alpha impairs chorionic gonadotrophin beta-subunit expression and cell fusion of human villous cytotrophoblast

Growth factors expressed at the fetal-maternal interface modulate hormone expression of placental trophoblasts. The aim of this study was to investigate the effects of different cytokines on hCG subunit mRNA expression in differentiating villous cytotrophoblasts. Quantitative real-time PCR revealed a 1.8- and 6.9-fold increase of hCG-alpha and hCG-beta mRNA levels, respectively, between 36 and 60 h of term trophoblast syncytialization. Compared with controls, neither interleukin (IL)-1beta, IL-2, IL-4, IL-6, IL-10, IL-13 and IL-15 nor tumour necrosis factor (TNF)-alpha significantly altered hCG-alpha mRNA expression. Similarly, the ILs did not affect hCG-beta transcript levels. In contrast, TNF-alpha suppressed hCG-beta mRNA 3.8- and 1.8-fold at 36 and 60 h of term trophoblast differentiation. Accordingly, hCG secretion was impaired by TNF-alpha but not by the different ILs. Moreover, TNF-alpha reduced luciferase expression of reporter plasmids harbouring the proximal hCG-beta5 promoter to 35 and 77%, respectively, in primary term trophoblasts and trophoblastic SHGPL-5 cells. In addition, counting of nuclei in syncytialized, desmoplakin-negative areas revealed a 1.9-fold reduction of term trophoblast fusion in the presence of TNF-alpha. Similarly, floating explant cultures prepared from first trimester-denuded villi recovered the syncytium 2.8-fold less efficiently during 72 h of cytokine treatment. Concomitantly, TNF-alpha impaired induction of endogenous and secreted hCG-beta protein levels in these cultures. The data suggest that TNF-alpha decreases hCG-beta mRNA and protein expression by reducing gene transcription and trophoblast cell fusion. Suppression of these processes by TNF-alpha could partly explain the adverse effects of the cytokine on placental function and pregnancy outcome.

Reduced uterine indoleamine 2,3-dioxygenase versus increased Th1/Th2 cytokine ratios as a basis for occult and clinical pregnancy failure in mice and humans

PROBLEM

Indoleamine 2,3-dioxygenase (IDO) expression in fetal trophoblast and decidual antigen-presenting cells has been proposed to inactivate maternal T cells and thereby prevent rejection of the "fetal allograft" in early pregnancy. Psychic stress has been proposed to cause miscarriages as well as infertility, at the same time in pregnancy when blockade of IDO causes loss, but the suggested mechanism of stress-triggered loss has been an increased ratio of pro-rejection Th1-type cytokines to anti-rejection Th2/3 cytokines. Could stress act by reducing IDO expression?

METHODS

Using DBA/2-mated A/J mice where stress causes early pregnancy failure, we examined the role of stress in reducing IDO versus increasing Th1/Th2 ratio in deciduas. IDO loss was also examined in human decidua associated with pregnancy failure.

RESULTS

A post-implantation sonic stress increased the pregnancy failure rate, increased the Th1/Th2 ratio, but did not reduce IDO. IDO was reduced, and Th1/Th2 ratios increased in A/J mice pre-immunized against paternal DBA/2 antigens, and concomitant stress increased these effects. The rate of pregnancy failure was not further increased consistent with recent discoveries of factors that limit the impact of Th1 cytokines at the feto-maternal interface. In deciduas from spontaneous miscarriage patients, IDO(+) cell frequencies were low in only 30% of patients. CD3(+) T-cell numbers and percentage terminal deoxynucleotidyl transferase (TdT)-mediated dUTP-digoxigenin nick end-labelling (TUNEL)(+) apoptotic T cells were increased, but the level of IDO did not correlate with likelihood of apoptosis.

CONCLUSIONS

Loss of an allogeneic embryo in early pregnancy is more likely to be due to a high Th1/Th2 ratio than loss of putative protection by IDO.

Nerve Growth Factor Translates Stress Response and Subsequent Murine Abortion via Adhesion Molecule-Dependent Pathways1

Spontaneous abortion is a frequent threat affecting 10%-25% of human pregnancies. Psychosocial stress has been suggested to be attributable for pregnancy losses by challenging the equilibrium of systems mandatory for pregnancy maintenance, including the nervous, endocrine, and immune system. Strong evidence indicates that stress-triggered abortion is mediated by adhesion molecules, i.e., intercellular adhesion molecule 1 (ICAM1) and leukocyte function associated molecule 1, now being referred to as integrin alpha L (ITGAL), which facilitate recruitment of inflammatory cells to the feto-maternal interface. The neurotrophin beta-nerve growth factor (NGFB), which has been shown to be upregulated in response to stress in multiple experimental settings including in the uterine lining (decidua) during pregnancy, increases ICAM1 expression on endothelial cells. Here, we investigated whether and how NGFB neutralization has a preventive effect on stress-triggered abortion in the murine CBA/J x DBA/2J model. We provide experimental evidence that stress exposure upregulates the frequency of abortion and the expression of uterine NGFB. Further, adhesion molecules ICAM1 and selectin platelet (SELP, formerly P-Selectin) and their ligands ITGAL and SELP ligand (SELPL, formerly P selectin glycoprotein ligand 1) respectively increase in murine deciduas in response to stress. Subsequently, decidual cytokines are biased toward a proinflammatory and abortogenic cytokine profile. Additionally, a decrease of pregnancy protective CD8alpha(+) decidual cells is present. Strikingly, all such uterine stress responses are abrogated by NGFB neutralization. Hence, NGFB acts as a proximal mediator in the hierarchical network of immune rejection by mediating an abortogenic environment comprised of classical signs of neurogenic inflammation.

Regulatory T cells induce a privileged tolerant microenvironment at the fetal-maternal interface

The mechanisms underlying immune tolerance during pregnancy are poorly understood. In this regard, Treg seem to play an important role in mediating maternal tolerance to the fetus. We proposed a crucial role of T regulatory cells (Treg) in avoiding immunological rejection of the fetus after observing diminished number and function of Treg in abortion-prone mice. We further confirmed the protective role of Treg during pregnancy by transferring pregnancy-induced Treg into abortion-prone mice, which prevented rejection. Here, we analyzed the mechanisms involved in Treg-mediated protection. As expected, Treg therapy prevented abortion, while expanding the peripheral and thymic Treg population. Surprisingly, the decidual levels of the Th1 cytokines IFN-gamma and TNF-alpha were not diminished after therapy. Interestingly, the mRNA levels of leukemia inhibitory factor, TGF-beta and heme oxygenase-1 at the fetal-maternal interface were dramatically up-regulated after Treg transfer, while the levels of indolamine 2,3-dioxygenase remained unchanged. Our data suggest that Treg treatment can not prevent T cell infiltration or high Th1 levels but is able to create a privileged tolerant microenvironment at the fetal-maternal interface, further shedding light onto the molecular mechanisms involved in pregnancy tolerance.

Comparative immunohistochemical study of M-CSF and G-CSF in feto-maternal interface in a multiparity mouse model

PROBLEM

Multiparity status has been found to bring beneficial effects both to the maintenance of pregnancy and to the offspring; however, these effects have not been fully explained. We have previously reported that placentae obtained from multiparous females belonging to a syngeneic mouse crossbreeding showed an important increase in the number of placental macrophages, suggesting that they might constitute a protective subpopulation. Taking into account that macrophage-colony stimulating factor (M-CSF) and granulocyte-colony stimulating factor (G-CSF) have proved to modulate macrophage activity and that both factors and/or their receptors have been found at feto-maternal interface, in this paper we analyzed the presence of M-CSF and G-CSF in placental tissue employing the same multiparity mouse model in order to investigate the influence of parity status on local immunoregulation factors of macrophage activity.

METHOD OF STUDY

Three groups of mice (CBA/J x CBA/J) were analyzed: Primiparous Young, 3.0 +/- 0.5 months old (PY); Primiparous Old, 8.5 +/- 0.5 months old (PO) and Multiparous Old, 8.5 +/- 0.5 months old, with three to four previous pregnancies (MO). The presence of M-CSF and G-CSF in placental tissue was analyzed by immunohistochemistry. Cytokeratin (CK) and vimentin (VIM) expression and PAS staining were also studied.

RESULTS

The three groups showed a similar immunostaining pattern for M-CSF in the whole placental trophoblast, while the expression of G-CSF was significantly higher only in the spongy zone in the MO group. Furthermore, all the MO placentae showed 5-11 layers of cells adjacent to the decidua, where G-CSF and M-CSF were highly detected. Conversely, they constituted a thin layer in PY and PO placentae. These cells were proved to be CK(+) and VIM(-) thus demonstrating their trophoblast origin. In addition, the layers closer to the decidua were also PAS+ suggesting that they could be interstitial cells, a type of invading trophoblast.

CONCLUSIONS

In our mouse model, we observed an increase in the expression of G-CSF in placental spongiotrophoblast cells in multiparous females, which have been previously proposed as progenitors of the interstitial cells. Furthermore, this is the first report that indicates that parity status increases trophoblast invasion inducing a proliferative effect of the invading cells on the maternal tissue. We suggest that M-CSF and G-CSF secreted by these invading cells could favor the recruitment of macrophages to the trophoblast and might modulate their activity inducing a switch to a protective, non-inflammatory population.

Galectin-15 in ovine uteroplacental tissues

Galectin-15 is the newest member of a secreted beta-galactoside-binding lectin family. The galectin-15 gene is expressed specifically by the endometrial luminal epithelium (LE) and superficial ductal glandular epithelium (sGE) of the ovine uterus. The proposed extracellular role of secreted galec7tin-15 is to regulate implantation and placentation by functioning as a heterophilic cell adhesion molecule between the conceptus trophectoderm and endometrial LE, while that of intracellular galectin-15 is to regulate cell survival, differentiation and function. The present study determined galectin-15 expression in uteroplacental tissues during gestation and in the postpartum uterus. In the uterine lumen, secreted galectin-15 was found as multimers, particularly on days 14 and 16 of pregnancy. In the endometrial epithelium and conceptus trophectoderm, intracellular galectin-15 protein was found associated with crystalline structures. Between days 20 and 120 of pregnancy, galectin-15 mRNA was expressed specifically by the LE and sGE of the intercaruncular endometrium of ewes. Immunoreactive galectin-15 protein was most abundant in the trophectoderm with lower levels in the endometrial LE and sGE. Galectin-15 protein was detected in allantoic fluid, but not in amniotic fluid. After parturition, galectin-15 mRNA declined in the endometrium from postpartum day (PPD) 1 to 28 and exhibited a variegated expression pattern in the LE and sGE. These results indicate that galectin-15 is synthesized and secreted throughout gestation by the endometrial LE/sGE and is absorbed by the placenta and forms crystals within the trophectoderm, whereas the remainder is cleared into the allantois after being transported into the fetal circulation via the placental areolae. Based on the biological properties of other galectin family members, galectin-15 is hypothesized to have biological roles in conceptus-endometrial interactions, uterine immune and inflammatory responses, and placental morphogenesis and function.

Anti-P- and E-selectin therapy prevents abortion in the CBA/J × DBA/2J combination by blocking the migration of Th1 lymphocytes into the foetal–maternal interface

Leukocyte migration into inflamed tissues comprises dynamic interactions between immune and endothelial cells through events controlled by adhesion molecules, e.g., P- and E-selectins, which mediate Th1 cells recruitment after injury. Since miscarriage is known to be a Th1 event and selectins are expressed at the murine foetal-maternal interface, the purpose of our study was to investigate whether blocking P- and E-selectins before implantation could inhibit Th1 migration into the foetal-maternal interface and thus prevent foetal rejection. DBA/2J-mated CBA/J females were treated with monoclonal antibodies (mAbs) against P-selectin or with both, anti-P- and anti-E-selectins combined on days 2 and 4 of pregnancy. PBS-treated females served as controls. Our data revealed a significant improvement in pregnancy outcome in both treated groups compared to the control, which is due to the effectiveness of the mAb against P-selectin, since the treatment with anti-E-selectin alone could not prevent abortion. We further observed that there was diminished Th1 cytokine production by decidual immune cells in all treated groups in comparison to the controls. Our data first confirm the important role of P-selectin in mediating the extravasation of abortive cells, while opening new therapeutic opportunities.

Impact of genes related to immune tolerance and inflammation (tumour necrosis factor-α, interleukin-6) on blood pressure, protein excretion and oedema in pregnancy

OBJECTIVE

To test the hypothesis that genetically determined alterations of maternal immune tolerance to a foetal semi-allograft are important for the pathogenesis of hypertensive disorders in pregnancy.

DESIGN

A genetic association study was performed to analyse the impact of genetic polymorphisms known to be involved in immune tolerance on markers of pre-eclampsia.

SETTING

The study was conducted at the Obstetrics Department of the Charité University Hospital, Berlin, Germany.

PARTICIPANTS

A total of 1480 Caucasian women were consecutively included after delivery and genotyped for two polymorphisms: tumour necrosis factor-alpha -308G>A and interleukin-6 -174G>C.

MAIN OUTCOME MEASURES

Systolic and diastolic blood pressures, urinary protein excretion and oedema during pregnancy.

RESULTS

Only women carrying at least one mutant allele of both polymorphisms (tumour necrosis factor-alpha A and interleukin-6 C) have a significantly elevated mean systolic blood pressure and diastolic blood pressure at the end of pregnancy. The tumour necrosis factor-alpha A allele on its own is significantly associated with urinary protein excretion in the last trimenon, and the interleukin-6 C allele is independently and significantly associated with new-onset oedema.

CONCLUSIONS

We demonstrate in a large population that common maternal polymorphisms of genes related to immune tolerance and inflammation are associated with blood pressure regulation, urinary protein excretion and oedema during pregnancy. The analysed polymorphisms seem to contribute to the multifactorial pathogenesis of gestational hypertension and pre-eclampsia. The findings support the hypothesis that genetically determined factors of maternal immune tolerance play a role in the pathogenesis of hypertensive disorders in pregnancy.

The role of dydrogesterone in recurrent (habitual) abortion

The published evidence regarding the administration of dydrogesterone in the treatment of habitual abortion is summarised in this review. Habitual abortion is defined as the loss of three or more consecutive pregnancies without known maternal or foetal pathology. The immunology of early pregnancy seems to determine the rejection or non-rejection of the allogenic embryo. When peripheral mononuclear cells from recurrent aborters are incubated with progesterone or dydrogesterone in vitro, T-helper (Th)2 cytokines such as interleukin (IL)-4 and IL-6 markedly increase whereas the Th1 cytokine interferon-gamma decreases. Additionally, both progesterone and dydrogesterone are thought to inhibit the activity of natural killer cells at the foeto-maternal interface in humans. Progesterone-induced blocking factor (PIBF) mediates the immunological effects of progesterone and dydrogesterone in pregnancy. It affects various phases of the maternal immune response involving both the cellular and humoral immune system, exerts anti-abortive effects and inhibits the release of arachidonic acid. It also favours the production of so-called asymmetric, pregnancy-protecting antibodies. In rodents, blockade of this factor results in the termination of pregnancy and in women considerably lower levels are found in those with threatened abortion or pre-term labour. In order to draw final conclusions as to the usefulness of dydrogesterone in women with a history of recurrent miscarriage, further controlled, blinded, randomised clinical trials are needed.

Upregulation of Bcl-2 at the foetal-maternal interface from mice undergoing abortion

Several burning questions remain unanswered in pregnancy-related research. Pro- and anti-inflammatory cytokines orchestrate an intriguing interaction leading either to the development of a normal individual or to its rejection. Augmented Th1 cytokines' production is involved in immunological rejection of the foetus. Excessive production of Th1 cytokines, particularly of tumour necrosis factor (TNF)-alpha, also triggers apoptosis. Thus, in the present work we investigated the incidence of apoptosis in a well-known experimental model of Th1-induced abortion, characterized by increased local TNF-alpha levels. Apoptosis of lymphocytes as well as their Th1 and Th2 cytokine production were analysed by flow cytometry. TNF-alpha mRNA levels were additionally analysed by real time reverse transcription-polymerase chain reaction (RT-PCR) in placental and decidual samples. Total placental apoptosis activity was investigated by measuring caspase-3 activity and by TdT-mediated dUTP nick end label staining. Immunohistochemistry, Western blot and real time RT-PCR were used to localize and quantify several anti- and pro-apoptotic molecules at the foetal-maternal interface. Despite elevated Th1 levels at the foetal-maternal interface, mice undergoing abortion presented comparable apoptotic rates. Interestingly, we found a significant upregulation of the anti-apoptotic Bcl-2 protein at the foetal-maternal interface from abortion-prone mice, while no changes could be observed for pro-apoptotic molecules. In the light of our results, we conclude that there is no evidence of increased apoptosis in mice undergoing immunological abortion in spite of elevated TNF-alpha levels. This is probably due to a selective upregulation of anti-apoptotic pathways (i.e. Bcl-2) at the foetal-maternal interface as a compensatory and/or protective mechanism.

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.

Intercellular adhesion molecule-1/LFA-1 cross talk is a proximate mediator capable of disrupting immune integration and tolerance mechanism at the feto-maternal interface in murine pregnancies

Our understanding why a woman's immune system does not reject her histoincompatible fetus is still very limited. Distinct insights into the mechanisms involved in pregnancy maintenance may help us to prevent pregnancy complications, e.g., miscarriages or pre-eclampsia. Immune integration and tolerance at the feto-maternal interface appear to be indispensable for successful pregnancy maintenance. Little is known about the cross talk between ICAM-1, expressed on epithelium, endothelium, and APC, and its ligand, LFA-1, at the feto-maternal interface. However, based on the role of ICAM-1/LFA-1 in allograft acceptance or rejection upon transplantation, adhesion molecules are likely to interfere with successful pregnancy outcome. In this study, we tested the hypothesis that ICAM-1/LFA-1 pathways may be involved in pregnancy rejection in murine models. By blocking ICAM-1/LFA-1-mediated intercellular adhesion events, we show that fetal immune acceptance is restored in challenged pregnancies (e.g., upon exposure to sound stress), and adoptive transfer of LFA-1 cells into pregnant mice induces rejection only in abortion-prone mouse models. ICAM-1/LFA-1 cross talk leads to increased recruitment of proinflammatory cells to the implantation site, promotes dendritic cell maturation in the decidua, and subsequently induces additional local Th1 polarization via mature dendritic cells. Furthermore, our observations clearly point out that mechanisms of fetal tolerance, e.g., indoleamine 2,3-dioxygenase expression, presence of CD4+CD25bright regulatory T cells, and synthesis of asymmetric Abs, are ICAM-1/LFA-1 dependent. Hence, our data shed light on a hierarchical network of immune integration at the feto-maternal interface, in which ICAM-1/LFA-1 cross talk is clearly a proximate mediator capable of disrupting successful pregnancy maintenance.

Interleukin-4 gene polymorphism is not involved in the risk of recurrent pregnancy loss

PROBLEM

Enhanced secretion of type-2 T-helper (Th2) cytokine is a characteristic feature in normal physiological pregnancy. A study has demonstrated defective production of interleukine-4 (IL-4) and other Th2 cytokine in women with recurrent pregnancy loss (RPL). Several studies have suggested that IL-4 variable number of tandem repeat (VNTR) gene polymorphism is probably associated with different IL-4 production.

METHODS OF STUDY

The IL-4 VNTR genotypes were assessed in 109 Japanese women with RPL and 210 ethnically matched women experiencing at least one live birth and no spontaneous abortion.

RESULTS

No significant differences in IL-4 VNTR genotype frequencies were found between the RPL and the control [B1B1 genotype (reference); B1/B2 and B2/B2 genotypes, odds ratio, 0.91; 95% confidence interval, 0.58-1.45].

CONCLUSION

The present study suggests that the IL-4 VNTR allele is not a major genetic regulator in RPL.

Pregnancy Outcome in Recurrent Aborters is Not Influenced by Chlamydia IgA and/or G

PROBLEM

It is unclear whether chlamydia infection influences the miscarriage rate and immunological factors in patients with recurrent miscarriage.

METHOD OF STUDY

Chlamydia DNA, IgA and IgG to Chlamydia trachomatis, natural killer cell activity, complement 3 (C3), C4, hemolytic complement, antinuclear antibodies, antiphospholipid antibodies, prolactin, activated partial thromboplastin time, prothrombin time and fibrinogen were examined in 504 patients with a history of two or more consecutive first-trimester miscarriages. Subsequent pregnancy outcomes were compared between cases with and without antibodies to C. trachomatis.

RESULTS

Totals of 10 of 30 and 48 of 201 patients receiving no medication miscarried subsequently with and without chlamydia infection. Chlamydia IgA and/or IgG were associated with a high level of C3 but not other immunological and coagulatory parameters.

CONCLUSION

Antibodies to C. trachomatis do not influence subsequent pregnancy outcome in patients with a history of recurrent miscarriage.

Loss of Surface CD200 on Stored Allogeneic Leukocytes may Impair Anti-abortive EffectIn Vivo

PROBLEM

Prevention of spontaneous abortion by allogeneic mononuclear leukocyte immunotherapy has proven ineffective in the CBA x DBA/2 murine abortion model if the leukocytes are stored overnight before inoculation. The mechanism and generality of the phenomenon has not been elucidated.

METHODS

As prevention of recurrent abortion in the CBA x DBA/2 model requires allogeneic BALB/c lymphoid cells bearing paternal antigens and the tolerance-signaling molecule CD200 (OX-2), we evaluated effects of cell storage on cell surface CD200 expression using flow cytometry of fresh or stored cells stained with monoclonal anti-CD200 antibody. Release of putative CD200 molecules into culture supernatant during storage was tested by the ability of supernatants to block binding of anti-CD200 to freshly isolated cells. Similar studies were done using human peripheral blood mononuclear leukocytes. Possible binding of soluble CD200 to immunoglobulin G (IgG) molecules in plasma as a basis for the anti-abortive effect of intravenous immunoglobulin G (IVIG) was tested using the standard peripheral blood lymphocyte (PBL) natural killer (NK) cell lysis of (51)Cr-labeled K562 cells and monoclonal anti-human CD200 antibodies.

RESULTS

Loss of anti-abortive effect of BALB/c cells with overnight storage at 4 degrees C and blocking of protective effect of freshly isolated cells with anti-CD200 antibody was confirmed. Supernatants of stored cells acquired a low level of protective activity against abortion in the CBA x DBA/2 model. Cell surface CD200 was lost with overnight storage at 4 or 22 degrees C, and supernatants acquired the ability to block binding of anti-CD200 antibody to fresh cells. Similar results were obtained using human PBL. However, if cells were stored overnight in IgG containing plasma, binding was not blocked. Suppression of NK cell lysis by PBL was abrogated if anti-CD200 antibody was added to the assay.

CONCLUSIONS

Loss of the tolerance signal CD200 from allogeneic cells occurs with storage overnight, and their ability to protect against abortion is lost. CD200 appears to be shed into the supernatant, and may associate with IgG molecules rendering IVIG suppressive.

An Insight into the Dendritic Cells at the Maternal-Fetal Interface

The conditions that permit the genetically distinct fetus to survive and develop within the mother are among the most fascinating immunologic puzzles. The presence of dendritic cells in the maternal decidua pointed to a biologic role of antigen-presenting cells in maternal-fetal interaction. The method of study included recent findings on the lineage, maturity, phenotype and function of dendritic cells at the maternal-fetal interface. The increment of uterine dendritic cells occurs simultaneously with the decisive phase of gestation, when implantation takes place. Decidual dendritic cells of the first trimester pregnancy, with a phenotype characteristic of the mature myeloid lineage, express MHC class II, co-stimulatory and adhesion molecules, control Th1/Th2 balance and activate the proliferative response of autologous NK cells. Dendritic cells are specifically equipped to control immunity, to trigger immune response and also to maintain tolerance, avoiding the rejection of the conceptus by the maternal immune system.

Ecology of Danger-dependent Cytokine-boosted Spontaneous Abortion in the CBA × DBA/2 Mouse Model. I. Synergistic Effect of LPS and (TNF-α + IFN-γ) on Pregnancy Loss

PROBLEM

Previous data have shown "danger" signals, such as bacterial lipopolysaccharide (LPS) acting via toll-like (tlr) receptors are required for early pregnancy failure in several murine abortion models. Indeed, the abortion rate increased in the CBA x DBA/2 model after a gestation day (gd) 7.5 injection of tumour necrosis factor (TNF)-alpha + interferon (IFN)-gamma only if the LPS-tlr signalling pathway was intact. High rates of cytokine-boosted abortion >80% loss can be achieved in certain animal colonies, that have a high endogenous (spontaneous) rate of resorption (30-50%). A specific role for LPS has been postulated to determine both the endogenous and cytokine-boosted losses.

METHODS

To test the role of LPS in spontaneous and cytokine-boosted abortions, recombinant TNF-alpha + IFN-gamma, and LPS were injected in different doses and sequences intraperitoneally (i.p.) into CBA x DBA/2 mated mice in the Toronto General Research Institute animal facility where the endogenous abortion rate is <30%. The effects of poly IC, a tlr3 agonist that induces IFN-gamma that can reverse LPS-induced tolerance, and effects of anti-MD-1 on TNF-alpha induction by LPS, poly IC, CPG, or HSP in vitro were also examined.

RESULTS

A high endogenous rate of loss similar to that seen in Clamart could be achieved by increasing exposure to LPS on the morning after mating (gd 0.5). The magnitude by which the abortion rate could be increased by an i.p. injection of 2000 u TNF-alpha + 1000 u IFN-gamma on gd 7.5 was independent of the endogenous rate of loss, and could not be increased by doubling the dose. One microgram of LPS given on day 7.5 achieved a similar rate of loss, and if given with the cytokines, synergistically boosted the rate of loss to near Clamart rates. LPS given 1 day prior to the cytokines abrogated the cytokine effect, whereas LPS given day 0.5 had no significant effect on the response to day 7.5 cytokine injection. Blocking MD-1 inhibited TNF-alpha stimulation by poly IC, LPS, CPG, or HSP in vitro, and reduced abortion rates. Poly IC did not avert LPS-type tolerance effects in vivo.

CONCLUSIONS

High endogenous rates of abortion in the CBA x DBA/2 model may be explained by exposure to LPS at the time of mating. Increased rates of loss triggered by cytokines later in pregnancy may depend on increased absorption of LPS from intestinal flora.

To die or not to die: the function of the transcription factor NF-kappaB in embryos exposed to stress

BACKGROUND

Cytokines operating in the embryo and embryonic microenvironment determine, to a significant extent, whether pregnancy is completed successfully or results in embryonic loss or maldevelopment. They act as activators of specific transcription factors, which control cell responses such as cell proliferation differentiation and apoptosis. One such transcription factor is the nuclear factor-kappaB (NF-kappaB), which is presently seen as a key molecule controlling the apoptosis process. In the light of evidence that a majority of embryopathic stresses, regardless of their nature, first disturb the apoptotic process, it is conceivable, that NF-kappaB may play an important role in regulating the resistance of embryos to embryopathic stresses. In this brief review, we discuss such a possibility based on data characterizing expression and function of NF-kappaB in the embryo and extraembryonic tissues during normal embryogenesis as well as after exposure to various embryopathic stresses.

METHODS

Critical review of existing data.

RESULTS

Data summarized in this review suggest that (a) practically all NF-kappaB/Rel family members are expressed in embryonic, trophoblast and uterine cells in a developmental stage- and cell type-specific manner; (b) NF-kappaB-mediated anti-apoptotic signaling in embryonic cells seems to be indispensable for proper development during the organogenesis stage, (c) NF-kappaB activity in stress-targeted embryonic and extraembryonic structures directly correlates with their ability to resist stress-induced process of embryo loss and maldevelopment.

CONCLUSION

Data presented in this review suggest that NF-kappaB may act as a protector of embryos exposed to embryopathic stresses, possibly, because of the ability of NF-kappaB to prevent the induction of programmed cell death as well as to activate cell proliferation.

Depletion of CD8+ cells abolishes the pregnancy protective effect of progesterone substitution with dydrogesterone in mice by altering the Th1/Th2 cytokine profile

One of the most remarkable immunological regulations is the maternal immune tolerance toward the fetal semiallograft during pregnancy, which has been referred to as immunity's pregnant pause. Rejection of the semiallogeneic trophoblast cells must be selectively inhibited and pathways presumably include Th2 cytokines unopposed by Th1 cytokines. Steroid hormones, including progesterone, have similar effects. Low levels of progesterone and Th2 cytokines and high levels of Th1 cytokines are attributable for increased abortions in mammalians, which may be triggered by psychoemotional stress. Thus, the aim of the present study was to provide experimental evidence for the mechanism involved in the mediation of immune responses by endocrine signals during pregnancy and stress-triggered pregnancy failure. DBA/2J-mated CBA/J female mice were randomized in three groups: 1) control females, 2) mice exposed to stress on gestation day 5.5, and 3) mice exposed to stress and substituted with dydrogesterone, a progestogen with a binding profile highly selective for the progesterone receptor on gestation day 5.5. On gestation days 7.5, 9.5, and 10.5, mice of each group were sacrificed, and the frequency of CD8(+) cells and cytokine expression (IL-4, IL-12, TNF-alpha, IFN-gamma) in blood and uterus cells was evaluated by flow cytometry. Additionally, some mice were depleted of CD8 cells by injection of mAb. We observed that progesterone substitution abrogated the abortogenic effects of stress exposure by decreasing the frequency of abortogenic cytokines. This pathway was exceedingly CD8-dependent, because depletion of CD8 led to a termination of the pregnancy protective effect of progesterone substitution.

Nerve growth factor and its functional receptor TrkA are up-regulated in murine decidual tissue of stress-triggered and substance P-mediated abortion

PROBLEM

Stress, elicited by environmental and social conditions, is known to affect the homeostasis of the nervous, endocrine and immune systems. In pregnancy, perceived stress results in a predomination of inflammatory abortion-associated Th1 cytokines over immunosuppressive, pregnancy-protective-associated Th2 cytokines, putatively via neuropeptide substance P (SP). Nerve growth factor (NGF), an important trophic factor for sympathetic neurons, has been implicated in the responsiveness of immune-competent cells through its functional receptor, tropomyosin receptor kinase (TrkA). Thus, the aim of the present study was to identify a cross-talk between distinct neurotrophic and immune mediators in pregnancy maintenance.

METHOD OF STUDY

Using immune fluorescence, we evaluated decidual and placental expression of NGF and TrkA on gestation day (gd) 13.5 in the abortion-prone mouse model CBA/J x DBA/2J in (1) CBA/J female control mice; (2) CBA/J mice exposed to stress on gd 5.5; and (3) CBA/J mice injected with SP on gd 5.5 to mimick stress perception.

RESULTS

Stress and SP injection significantly increased the abortion rate and up-regulated decidual NGF and TrkA expression compared with the control. Stress, but not SP injection down-regulated placental NGF, whereas no changes in placental TrkA were observed.

CONCLUSION

Our data suggest a functional role for NGF in stress-triggered, SP-mediated abortion.

Therapy with dendritic cells influences the spontaneous resorption rate in the CBA/J x DBA/2J mouse model

PROBLEM

DBA/2J-mated CBA/J female mice are prone to a high incidence of fetal abortions. This fetal wastage can be dramatically reduced by immunizing the female mice with BALB/c, but not with DBA/2J spleen cells during early gestation. Nevertheless, the underlying mechanisms remain to be elucidated. Recently, dendritic cells (DC) have been described at the feto-maternal interface in the human uterus. In this work, we studied the effect of adoptive transfer of DC on the maintenance of pregnancy in the CBA/J x DBA/2J model.

METHODS

Bone marrow-derived DC were generated from virgin female CBA/J mice (6-8 weeks old). CBA/J females were inoculated with DC twice before mating. Four different experimental groups were included: (i) no treatment control, (ii) mice injected with culture medium [granulocyte-macrophage colony-stimulating factor (GM-CSF)], (iii) immunized with DC and (iv) immunized with paternal DBA/2J antigens lisate-pulsed DC, n = 5.

RESULTS

The control abortion rate was 23.8%, and with GM-CSF alone was 17.6%. Following inoculation of syngeneic DC abortion rates were reduced to 2.2%, but protection was short-lived. Abortion rates with DC pulsed with DBA/2J antigens was 5%. Serum of interleukin (IL)-6 levels were lower in the latter two groups up to the time of abortion. The kinetics of immunoglobulin G asymmetric antibodies synthesis was modified, but there was no correlation between asymmetric antibodies production and the lowering of abortions rates.

CONCLUSION

Syngeneic DC prevented abortions and this was linked to a decrease in IL-6 levels, but not with levels of asymmetric antibodies.

Increased Expression of Pro-Inflammatory Cytokines in Placentas of Women Undergoing Spontaneous Preterm Delivery or Premature Rupture of Membranes

PROBLEM

The objective of this study was to determine the levels of cytokines in the placentas of women undergoing preterm delivery (PTD) or premature rupture of membranes (PROM) as compared with women undergoing normal delivery at term.

METHOD OF STUDY

Placentas were obtained from 30 subjects with spontaneous PTD, 30 women with PROM and 30 women with a history of normal delivery at term. Levels of interleukin (IL)-2, interferon (IFN)-gamma, tumor necrosis factor (TNF)-alpha, TNF-beta, IL-4, IL-5, IL-6 and IL-10 and IL-12 were estimated by ELISA in detergent lysates of placentas from the subjects.

RESULTS

We found significantly increased levels of the Th1 cytokines IL-2 and IFN gamma and of the Th1-inducing cytokine IL-12 in placentas from the PTD and PROM groups as compared with those delivering at term. In contrast, the levels of the Th2 cytokines IL-4, IL-6 and IL-10 were significantly higher in placentas from term pregnancy.

CONCLUSIONS

These data support our observation of a pro-inflammatory cytokine bias in women with PTD and PROM.

Fetal and Maternal Transforming Growth Factor-β1 May Combine to Maintain Pregnancy in Mice1

One of the mysteries of pregnancy is why a mother does not reject her fetuses. Cytokine-modulation of maternal-fetal interactions is likely to be important. However, mice deficient in transforming growth factor-beta1 (TGF beta 1) and other cytokines are able to breed, bringing this hypothesis into question. The phenotype of TGF beta 1 null-mutant mice varies with genetic background. We report here that, in outbred mice, the loss of TGF beta 1-deficient embryos is influenced by the parity of their mother. This is consistent with the loss of mutants being due to immune rejection. An inbred line of TGF beta 1(+/-) mice that supported TGF beta 1-deficient fetuses had high levels of TGF beta 1 in their plasma. Analysis of the amniotic fluids in this line indicated that biologically relevant levels of maternal TGF beta 1 were present in the TGF beta 1(-/-) fetuses. These data are consistent with maternal and fetal TGF beta 1 interacting to maintain pregnancy, within immune-competent mothers.

Human Miscarriage is Associated with Increased Number of CD26+ Decidual Lymphocytes

Dipeptidyl peptidase-IV (DPP-IV, CD26), a serine protease with broad distribution in mammalian tissues and known activity in serum, participates in T-cell activation and promotes a Th1-like cytokine response. Previous data on murine abortion indicate that DPP-IV may play a critical role in pregnancy failure by inducing a Th1 local response. Here, we investigated the possible participation of DPP-IV in the onset of human spontaneous abortion (SA). The systemic (peripheral blood) and local (decidua) percentages of CD4(+), CD8(+), CD26(+) and CD56(+) cells as well as the number of Th1 lymphocytes (CCR5(+) cells) were assessed in samples from women after SAs (n = 20) and from women with normally progressing pregnancies (NPs) (n = 27) using flow cytometry and immunohistochemistry. We further measured the DPP-IV activity and concentrations of Th1 (interferon-gamma and tumour necrosis factor-alpha), Th2 [interleukin-4 (IL-4), IL-10] and Th3 (transforming growth factor-beta2) cytokines in serum samples. We could not find any difference in the number of CD4(+), CD8(+), CD26(+), CD26(+)/CD4(+) or CD8(+)/CD26(+) blood cells between NP and SA patients. No differences in the Th1, Th2 or Th3 cytokine levels could be observed between both groups. However, the percentages of decidual CD26(+) lymphocytes as well as the number of decidual Th1 cells were significantly higher in SA samples compared to samples from patients with NP. Our data support the hypothesis that CD26(+) decidual lymphocytes with DPP-IV activity may play a critical role in SAs, as previously suggested in an abortion mice model. This abortive effect may be mediated by enhancing the levels of Th1 abortogenic cytokines only locally.

Single nucleotide polymorphisms in the promoter region of the interleukin-6 gene and the risk of recurrent pregnancy loss in Japanese women

OBJECTIVE

To investigate the relationships between recurrent pregnancy loss and single nucleotide polymorphisms (-634C-->G and -174G-->C genotypes) in the promoter region of the interleukin (IL)-6 gene in the Japanese population.

DESIGN

A case-control study.

SETTING

Obstetrics and gynecology department of a university hospital.

PATIENT(S)

Cases were 76 women with recurrent pregnancy loss; controls were 93 fertile women.

INTERVENTION(S)

Determination of IL-6 promoter gene polymorphisms performed by polymerase chain reaction and gel electrophoresis.

MAIN OUTCOME MEASURE(S)

Frequency and distribution of the promoter region of the IL-6 gene allele.

RESULTS

There was a significant difference in the -634C-->G genotype frequency (CC vs. CG/GG) between women with recurrent pregnancy loss and controls. The risk of recurrent pregnancy loss was lower in the carriers of the G allele than in women with the wild type (CC) (odds ratio = 0.46; 95% confidence interval = 0.24-0.91). On the other hand, we did not detect any carrier of -174C among the 169 subjects.

CONCLUSION(S)

The results suggest that, in the Japanese population, women carrying the -634G allele of the IL-6 gene might have a decreased risk of recurrent pregnancy loss.

The Effect of Valacyclovir Treatment on Natural Killer Cells of Infertile Women

PROBLEM

The aim of this study was to investigate the effect of valacyclovir treatment on natural killer (NK) cell concentration in the peripheral blood of infertile women.

METHOD OF STUDY

Peripheral blood NK cell concentration of 104 non-pregnant women with a history of infertility was determined by flow cytometry. The controls were 14 fertile non-pregnant women. A cohort of 42 out of 104 women--whose NK cell levels were 175/microL or higher--was prospectively studied for the presence of HSV-1, 2, VZV, cytomegalovirus, HHV-6, HHV-7 and HHV-8 DNA in the peripheral blood and was orally administered valacyclovir (open label study).

RESULTS

Herpes virus DNA was detected in 64.3% of the 42 women examined. Prior to valacyclovir treatment mean NK cell concentration in herpes-negative group was statistically higher from control group but lower from herpes positive group (P = 0.0007, ANOVA). Following valacyclovir treatment the mean NK cell concentration was statistically decreased in all studied women (P = 0.000453), in herpes-negative (P = 0.01622) and in herpes positive group (P = 0.0056). Sufficient decrease was observed in 31 (73.8%) of 42 women who received the drug.

CONCLUSIONS

Valacyclovir treatment is associated with a decrease of NK cell levels in most of the women with a history of infertility.

Searching for links between endotoxin exposure and pregnancy loss: CD14 polymorphism in idiopathic recurrent miscarriage

PROBLEM

Lipopolysaccharide (LPS) (endotoxin) is a well-known inducer of abortions in mice. In addition it has been proposed that gut-derived LPS of gram-negative bacteria may play a role in triggering idiopathic recurrent miscarriage (IRM) in humans. CD14 is one of the key molecules that mediates the effects of LPS. Promoter region polymorphism (-159C/T) in the CD14 gene is functionally important by regulating CD14 levels. High-producing CD14 genotype (TT) associates with deleterious effects of gut-derived LPS in hepatic cirrhosis in humans. It is not known whether women with IRM are genetically more prone to suffer from toxic effects of LPS.

METHOD OF STUDY

By using polymerase chain reaction we analyzed the CD14 promoter region polymorphism in 38 women with IRM and in 127 normal controls of Finnish origin.

RESULTS

There were no significant differences in the CD14 (-159C/T) allele or the genotype frequencies between the IRM women and the controls. However, there was a trend associating the presence of the T allele with increased odds of miscarriage.

CONCLUSIONS

Although we were not able to find a statistically significant association between CD14 genotypes and IRM in our relatively small study population, a further study with a larger sample size is warranted to explore the role of high-producing CD14 genotypes in IRM. Also studies highlighting environmental LPS triggers and other intrinsic mediators of LPS signalling are needed to solve the enigmatic role of LPS in IRM in humans.

Increasing circulating T-cell activation markers are linked to subsequent implantation failure after transfer of in vitro fertilized embryos

PROBLEM

Implantation determines success of in vitro fertilization (IVF) and embryo transfer (ET) cycles. Data are accumulating to support a role of the immune system in implantation. Most of the literature addresses the importance of natural killer (NK) cells in this process. The purpose of the current study is to examine the role of circulating T cells in implantation failure.

METHOD OF STUDY

Blood from 22 women undergoing IVF/ET during November, 2001, was drawn on cycle day 9 and analyzed for the percentage of circulating T cells expressing the activation markers CD69+ and human leukocyte antigen (HLA)-DR and the suppressor marker CD11b using immunofluorescence and flow cytometry. These results were compared with total percentage circulating CD3, CD4 and CD8 cells as well as NK cells and pregnancy outcome that cycle.

RESULTS

Infertile women had significantly greater expression of the activation marker of CD69+ among CD8+ and CD4+ T cells and HLA-DR among CD4 cells than fertile women. No difference in expression of T cell suppressor marker of CD11b was noted when infertile and fertile women were compared. No correlations were observed when activated T cells were compared with circulating CD3+, CD4+, CD8+, activated NK cells and NK cytotoxicity. CD3+ 4+ HLA-DR+ was expressed significantly less among successfully pregnant compared with unsuccessfully pregnant women.

CONCLUSION

T-cell activation markers CD 69+ and HLA-DR+ are associated with increased implantation failure after IVF/ET.

Analysis of Macrophage Presence in Murine Placenta: Influence of Age and Parity Status

PROBLEM

Beneficial effects of multiparity status have been previously reported by different authors. However, this fact has not been fully explained. Taking into consideration the influence of the parity status on the in vitro asymmetric/protective antibodies and the fact that interleukin-6 (IL-6) is involved in the production and immune-regulatory functions of placental macrophages, the aim of this work was to compare the placental IL-6 production and tissue macrophage presence in mice with different age and parity status.

METHOD OF STUDY

Three groups of mice (CBA/J x CBA/J) were analyzed: primiparous young (PY: 3.0 +/- 0.5 months old), primiparous old (PO: 8.5 +/- 0.5 months old), and multiparous old (MO: 8.5 +/- 0.5 months old, with three to four previous pregnancies). Macrophage and IL-6 were identified in placental tissue by immunohistochemistry employing anti-F4/80 or anti-IL-6 antibodies. IL-6 secretion was analyzed in the placental culture supernatants by enzyme-linked immunosorbent assay.

RESULTS

The results obtained indicate that, despite the level of macrophages observed in the PO placentae was higher than in PY ones, their expression in MO placentae was very much increased, appearing like a thick layer between decidua and trophoblast. However, no significant difference was found among the groups in the tissue expression of IL-6 and in IL-6 secreted in vitro.

CONCLUSIONS

Our data indicate that parity status influences the number of local macrophages and might provide evidence that could explain the known beneficial effect of multipaternity. We suggest that the number of previous pregnancies favor the production of a 'protective' population of macrophages.

Murine abortion is associated with enhanced interleukin-6 levels at the feto-maternal interface

CBA/JXDBA/2J murine abortion is known to be associated with increased local and peripheral Th1-cytokines levels. The role of the pro-inflammatory interleukin-6 (IL-6) in murine abortion remains unclear. In humans, IL-6 was reported to be elevated at the onset of spontaneous abortion. The aim of our study was to evaluate the levels of IL-6 during murine pregnancy in (1) the normal murine pregnancy combination CBA/JXBALB/c and in (2) the CBA/JXDBA/2J abortion prone mating combination. We measured IL-6 serum levels by ELISA and local (placental and decidual) IL-6 levels by flow cytometry and immunohistochemistry. The expression of the IL-6 receptor gp80 was further analyzed. We additionally evaluated the number of mast cells and macrophages at the feto-maternal interface as a putative IL-6 source in reproductive tissues. IL-6 and gp80 were expressed in decidual cells as well as in different trophoblast types. Flow cytometry analysis showed increased numbers of IL-6+ cells in abortion placentas and deciduas compared to control pregnant mice. We observed an elevated number of mast cells and macrophages at the feto-maternal interface from abortion mice in comparison to control mice. Interestingly, we found very high numbers of mast cells, macrophages and IL-6+ cells in resorption tissue compared to control tissues. Flow cytometry studies confirmed that macrophages are being an important source of IL-6 at the feto-maternal interface. The mRNA IL-6 levels were also enhanced in placenta and decidua from mice with high abortion rate compared to normal pregnant mice, as analyzed by RT-PCR. Our results suggest that IL-6 produced not only by immunocompetent cells such as macrophages and mast cells, but also by trophoblasts and decidua cells, is directly involved in the pathology of abortion.

Materno-fetal Immunogenetic Disparity: The Biological Basis for In vitro Fertilization Treatment in Patients with Unexplained Recurrent Abortion?

PROBLEM

The majority of women with recurrent miscarriage have no discernible cause but it has been postulated that immunologic aberrations may be the cause in most of such cases. Also, it has been stressed that deliberate modification of the maternal host defense system can improve the chances of success. We tested the hypothesis that it is possible to potentiate maternal immune functions so as to improve reproductive performance by replacing several embryos into the uterus, thus favoring the recognition of fetal antigens.

METHOD OF STUDY

A total of 57 couples with three or more (mean 5.52; range 3-12) consecutive first-trimester spontaneous clinical abortions of unknown etiology were treated with in vitro fertilization (IVF) and embryo transfer for a total of 84 cycles. Patients underwent IVF after combined gonadotropin-releasing hormone agonist/gonadotropin treatment for ovarian stimulation, and up to four embryos were replaced into the uterus.

RESULTS

There were 32 pregnancies (three of them after frozen-thawed embryo transfers) and 26 (81%) of them were viable gestations. Overall, patients had a previous obstetric history of 315 pregnancy losses and 15 live-born babies. Thus, the probability of having a live baby before treatment was 4.54% (95% CI, 2.78-7.36) a figure significantly lower (P < 0.0001) than that observed under IVF treatment (81%; 95% CI, 64.53-91.01). None of selected variables potentially related with the outcome of pregnancy after IVF and embryo transfer in recurrent aborters (including pre-implantation genetic diagnosis) was found to be associated with miscarriage.

CONCLUSIONS

This study shows that replacement of several embryos after IVF is a useful treatment in the prevention of unexplained recurrent spontaneous abortion thus providing further evidence for immunologically modifiable pregnancy loss.

Fraction of the peripheral blood concentration of CD56+/CD16−/CD3− cells in total natural killer cells as an indication of fertility and infertility

OBJECTIVE

To determine whether the peripheral blood concentration of CD56(+)/CD16(-)/CD3(-) cells, the main natural killer (NK) subpopulation that colonizes the endometrium in the middle and late secretory phase, can be related to fertility or infertility status.

DESIGN

A case control study.

SETTING

Immunopathology department of an infertility laboratory.

PATIENTS

A total 99 women were selected (group I: consecutive spontaneous aborters, n = 25; group II: sporadic spontaneous aborters, n = 30; group III: infertile, n = 33; group IV: controls, n = 11).

INTERVENTION

Immunophenotyping of women grouped according to their fertility status.

MAIN OUTCOME MEASURES

Peripheral blood lymphocytes were examined by two- and three-color flow cytometry.

RESULTS

A statistically significant association between endometrial-type peripheral blood (PB) NK cell concentrations and fertility status (groups I and IV vs. groups II and III) was documented. The %(/TOTAL PB)(CD56+CD16-CD3-) NK cells was significantly higher [1] in fertile (groups I and IV) than in sporadic aborters/infertile (groups II and III) women, [2] in group I when compared with groups II and III, and [3] in group IV when compared with groups II and III.

CONCLUSIONS

This study indicates that diminished numbers of the %(/TOTAL PB)(CD56+CD16-CD3-) NK cells are related to sporadic aborters and infertile women. Thus, the fraction could be used as an indicator of subsequent successful implantation and maintenance of gestation.

Placental Trophoblast from Successful Human Pregnancies Expresses the Tolerance Signaling Molecule, CD200 (OX-2)*

PROBLEM

Th1 cytokine-dependent abortions in the CBA x DBA/2 mouse model have been linked to down-regulation of expression of the CD200 (OX-2) 'tolerance' signal on trophoblast and in decidua prior to onset of the abortion process. Abortions could be prevented by administration of a soluble CD200. Is CD200 expressed on trophoblast in successful human pregnancy?

METHOD OF STUDY

As one cannot easily obtain trophoblasts in large quantities from successful human pregnancies in the first trimester prior to the onset of the abortion process at 6 weeks gestation, we examined as a first step, trophoblast isolated from term placentae (i.e. successful pregnancies). CD9- trophoblasts were isolated by affinity column and stained for intracellular cytokeratin, and surface CD200 using PE-anti-human CD200 monoclonal antibody. mRNA was extracted from CD9+ and CD9- cells and tested by reverse transcription-polymerase chain reaction for CD200 mRNA. CD9- placental cells were separated by velocity sedimentation and test for CD200-dependent suppression of an allogeneic human mixed lymphocyte culture where cytotoxic T cell (CTL) generation, and Thl --> Th2 cytokine production shift were measured.

RESULTS

CD9- but not CD9+ placental cell populations contained cells with mRNA for CD200, both a normal length transcript and a truncated transcript. Flow cytometry showed a CD200+ cytokeratin+ moderate-to-large-sized cell population compatible with trophoblasts and a smaller subset of cytokeratin- cells that expressed CD200 at normal and at high levels. The moderate-sized population proved most potent at inhibiting CTL generation and caused a Th1 --> Th2 cytokine shift. These effects were blocked by monoclonal anti-CD200.

CONCLUSIONS

A subpopulation of cytokeratin+ placental trophoblasts express bioactive CD200 able to alter maternal immune responses in a favorable (Th2 > Th1) direction. Two populations of CD200+ small- and medium-small-sized cytokeratin- placental cells remain to be identified. Studies of karyotyped first trimester elective termination and spontaneous miscarriage tissues are needed.

Pro-inflammatory maternal cytokine profile in preterm delivery

PROBLEM

The objective of this study was to determine the levels of cytokines produced by maternal peripheral blood mononuclear cells (PBMC) upon stimulation with a mitogen, with autologous placental cells and with a trophoblast antigen extract.

METHOD OF STUDY

Peripheral blood mononuclear cells from 54 women with a history of successful pregnancy and 30 women undergoing preterm delivery (PTD) were stimulated with the mitogen and antigens, and the cytokine levels in mitogen-stimulated culture supernatants assessed.

RESULTS

Significantly higher levels of the type 1 cytokines, interferon (IFN)-gamma and interleukin (IL)-2, were produced by the PTD group than by the normal pregnancy group, which on the contrary showed significantly greater production of the type 2 cytokines, IL-4, IL-5 and IL-10. A comparison of the ratios of type 2 to type 1 cytokines is indicative of a type 1 cytokine bias in PTD.

CONCLUSIONS

These data are suggestive of a maternal type 1 cytokine bias in PTD.

MD-1 is a critical part of the mechanism causing Th1-cytokine-triggered murine fetal loss syndrome

PROBLEM

Fetal loss syndrome (abortion/resorption) occurring on or after gestation day (gd) 9.5 in CBA/JxDBA/2 matings is dependent upon presence of TNF-alpha + IFN-gamma, which act by increasing expression of fg12 prothrombinase at the feto-maternal interface. The magnitude by which the abortion rate can be boosted by an injection of these cytokines on gd 7.5 depends on endogenous rate of loss, and appears to depend on microbial flora. Is cytokine-triggered abortion dependent upon a third signaling pathway that senses 'danger'?

METHODS

Female CBA/J were mated to DBA/2 males and, C57B1/6 and C57B1/6 TNFalphaR1-/-Mak were mated to C57B1/6 control or TNFalphaR1-/-Mak males. LPS from Escherichia coli and Salmonella enteritidis, or the combination of TNF-alpha + IFN-gamma, was injected to stimulate abortions. The effect of anti-MD-1, which interferes with expression of CD14 and, hence, with signaling by LPS via the CD14-tlr4 complex, on TNF-alpha + IFN-gamma was tested. The presence of MD-1 in the uterus was evaluated by in situ hybridization, and effect of lipopolysaccharide (LPS) on mice lacking TNF-alphaR1 was tested.

RESULTS

Anti-MD-1 completely abrogated TNF-alpha + IFN-gamma-induced abortions. MD-1 was expressed on trophoblast and in deciduas on gd 8.5 but LPS could not abort mice that lacked the type 1 receptor for TNF-alpha. Pregnant CBA/J females had classical resorptions (abortions) countable on gd 13.5-14.5 in response to LPS from E. coli or S. enteritidis, but C57B1/6 strain mice resorbed only in response to the latter, and E. coli LPS appeared to induce 'occult' losses. 'Occult' loss did not require TNF-alphaR1.

CONCLUSIONS

TNF-alpha + IFN-gamma could not induce murine abortions without co-presence of a 'danger' signal such as LPS acting via CD14 on toll receptors, and LPS could not act without co-signaling by TNF-alpha. Classical resorptions/abortions and 'occult' losses have a different mechanism in these models as reflected in type of endotoxin and requirement for TNF-alphaR1 signaling.

Th1 cytokines and the prothrombinase fgl2 in stress-triggered and inflammatory abortion

PROBLEM

The immune system contributes to the outcome of pregnancy by complex immunological interactions. Cytokines especially influence the immune milieu pro or contra pregnancy. T helper 1 (Th1) cytokines [tumor necrosis factor-alpha (TNF-alpha) and interferon-gamma (IFN-gamma)] cause inflammation and together are thought to threaten the maintenance of pregnancy. It has been proposed that increased levels of these Th1 cytokines activate coagulation via up-regulating the novel prothrombinase, fgl2. This study further investigates the Th1 cytokine up-regulation of fgl2 expression in a pathophysiological, stress induced abortion model, and an inflammatory, interleukin-12 (IL-12) triggered abortion model.

METHOD

The DBA/2J-mated CBA/J female mice were exposed to sonic sound stress or were injected with IL-12 during early gestation. On day 13.5 of pregnancy the uteri were removed and the resorption rate was calculated. We evaluated TNF-alpha, IFN-gamma, fgl2 as well as IL-12 messenger RNA (mRNA) expression in decidual samples of all mice by quantitative, real-time polymerase chain reaction (PCR).

RESULTS

A similar resorption rate of 24% was detected in stressed mice, as well as in IL-12 injected mice compared with approximately 11% in non-stressed, non-injected control mice. In stressed mice compared with controls, we observed on day 13.5 up-regulated TNF-alpha, unchanged IFN-gamma down-regulated fgl2, and a slightly increased levels of IL-12. In the IL-12 triggered abortion model, we observed up-regulated levels of TNF-alpha, IFN-gamma and fgl2.

CONCLUSION

These novel data suggest two distinct cytokine patterns leading to similar abortion rates. A physiological cascade associated with up-regulation of TNF-alpha, and an IL-12-triggered cascade characterized by persistent up-regulation of TNF-alpha and IFN-gamma as well as a persistent increase in fgl2.

IL-1 receptor antagonist gene polymorphism in recurrent spontaneous abortion

Genetic factors may contribute to the development of an aberrant pro-inflammatory immune response during pregnancy, thereby increasing the risk of some pregnancy-related pathologies such as recurrent spontaneous abortion (RSA). Interleukin 1 receptor antagonist is an important anti-inflammatory molecule encoded by the IL1RN gene, in which an intronic polymorphism has been described. Even though the molecular genetic mechanisms are not understood, this non-coding polymorphism, and especially IL1RN*2, has been associated with several chronic inflammatory and autoimmune diseases. IL1RN*2 is also associated with increased activity of IL-1beta, which is an important pro-inflammatory cytokine. We investigated the genetic variants of IL1RN in 37 Finnish women with RSA and 800 randomly selected Finnish blood donors. The women with RSA showed a significantly increased frequency of genotypes bearing the rare allele IL1RN*3 compared to the blood donors (10.8 vs 2.1%, odds ratio 5.6, 95% CI: 1.5-19.0, P=0.006). Our results suggest that IL1RN polymorphisms may predispose to RSA in a small subgroup of patients.

TNF-alpha in pregnancy loss and embryo maldevelopment: a mediator of detrimental stimuli or a protector of the fetoplacental unit?

PURPOSE

Tumor necrosis factor alpha (TNF-alpha), a multifunctional cytokine, has been identified in the ovary, oviduct, uterus, and placenta, and is expressed in embryonic tissues. For many years TNF-alpha was mainly considered to be a cytokine involved in triggering immunological pregnancy loss and as a mediator of various embryopathic stresses. However, data collected during the last decade has characterized TNF-alpha not only as a powerful activator of apoptotic, but also antiapoptotic signaling cascades, as well as revealed its regulatory role in cell proliferation. This review summarizes and conceptualizes the studies addressing TNF-alpha-activated intracellular signaling and the possible functional role of TNF-alpha in embryonic development.

METHODS

Studies addressing the role of TNF-alpha in intercellular signaling, in vivo studies addressing the functional role TNF-alpha in spontaneous and induced pregnancy loss, and studies addressing the role of TNF-alpha in fetal malformations were reviewed. Comparative studies in TNF-alpha knockout and TNF-alpha positive mice were performed to evaluate embryonic death, structural anomalies in fetuses, the degree of apoptosis and cell proliferation, and the activity of molecules such as caspases 3 and 8, the NF-kappaB, (RelA), IkappaBalpha in some target embryonic organs shortly after exposure to embryopathic stresses.

RESULTS

It is proposed that the possible essential function of TNF-alpha may be to prevent the birth of offspring with structural anomalies.

CONCLUSIONS

TNF-alpha will boost death signaling to kill the embryo if initial events (damages) triggered by detrimental stimuli may culminate in structural anomalies, and stimulate protective mechanisms if the repair of these damages may prevent maldevelopment.

Increased susceptibility to retinoid-induced teratogenesis in TGF-beta2 knockout mice

Transforming growth factor-beta (TGF-beta) and retinoic acid (RA) have been implicated in normal and abnormal embryonic development. The aim of this study was to investigate the effect of TGF-beta2 gene deletion on susceptibility to RA-induced teratogenesis in a mouse model. TGF-beta2 heterozygous or wild-type mice were mated and the dams dosed with a teratogenic dose of RA, or with control vehicle. The incidence of RA-induced cleft palate (CP) was 48% in wild-type embryos from wild-type dams, increasing to 71% in TGF-beta2 heterozygous littermates. Wild-type and TGF-beta2 heterozygous embryos from heterozygous dams exhibited a CP incidence of 74 and 77% respectively, following treatment with RA. Ninety-one percent of littermates nullizygous for TGF-beta2 were dead when examined; the remainder exhibited a CP. We conclude that the genotype of the dam and embryo with respect to TGF-beta2 affects the incidence of RA-induced teratogenesis.