Implantation: can immunological parameters of implantation failure be of interest for pre-eclampsia?

The Next Frontier in ART: Harnessing the Uterine Immune Profile for Improved Performance

Assisted reproduction techniques have improved considerably in recent decades, but despite these advances, success rates remain relatively low. Endometrial immune profiling involves the analysis of cytokine biomarkers in the endometrium during the mid-luteal phase. This profiling aims to provide insights into the immune environment of the uterus. The aim is to identify immune disturbances and thus guide the development of personalized therapeutic approaches. The first part of the review looks back at the emergence of innovative concepts, highlighting the specificity of the human uterine environment at the time of implantation. Based on this new knowledge, biomarkers have been selected for endometrial immune profiling. The second part details the results of clinical studies conducted over the last ten years. These clinical results suggest that this approach can increase the rate of live births in patients suffering from repeated implantation failures or repeated pregnancy loss. Uterine immune profiling represents a clinical innovation that can significantly improve the performance of medically assisted reproduction treatments through personalized strategies tailored to the local immune profile. Innovation in personalized medicine for assisted reproduction is crucial to improving the success rates of fertility treatments, while reducing the risks and costs associated with ineffective or unnecessary interventions.

Allogeneic lymphocytes immunotherapy in female infertility: Lessons learned and the road ahead

The endometrium is an essential tissue in the normal immunologic dialogue between the mother and the conceptus, which is necessary for the proper establishment and maintenance of a successful pregnancy. It's become evident that the maternal immune system plays a key role in the normal pregnancy's initiation, maintenance, and termination. In this perspective, the immune system contributes to regulating all stages of pregnancy, thus immunological dysregulation is thought to be one of the major etiologies of implantation failures. Many researchers believe that immune therapies are useful tactics for improving the live births rate in certain situations. Lymphocyte immunotherapy (LIT) is an active form of immunotherapy that, when used on the relevant subgroups of patients, has been shown in multiple trials to dramatically enhance maternal immunological balance and pregnancy outcome. The primary goal of LIT is to regulate the immune system in order to create a favorable tolerogenic immune milieu and tolerance for embryo implantation. However, there are a plethora of influential factors influencing its therapeutic benefits that merit to be addressed. The objective of our study is to discuss the mechanisms and challenges of allogeneic LIT.

Correlation between CYP11B2 polymorphism and the risk of preeclampsia

BACKGROUND

Many studies have evaluated the association between aldosterone synthase (CYP11B2) C-344T polymorphism and preeclampsia (PE) susceptibility, however, the results from different studies are inconsistent.

OBJECTIVE

The study aimed to derive a more precise estimation of this association.

METHODS

We searched PubMed, Embase, Chinese National Knowledge Infrastructure, China Biological Medicine, and Wanfang Database. The association was evaluated by calculating the odds ratios (ORs) with the corresponding 95% confidence intervals (CIs).

RESULTS

Seven case-control studies with a total of 720 cases and 766 controls were eligible to be included in this meta-analysis. Overall, there was no significant association between CYP11B2 C-344T polymorphism and PE (for the allele model T vs.C: OR=0.78, 95%CI 0.60-1.01, p=0.06; for the codominant model CT vs. CC: OR=1.08, 95%CI 0.80-1.46, p=0.63; for the dominant model TT + CT vs. CC: OR=0.91, 95%CI 0.68-1.20, p=0.49). Similar results were obtained in sensitivity analysis.

CONCLUSION

In summary, the present meta-analysis suggests that CYP11B2 C-344T polymorphism may not be associated with genetic susceptibility of PE, but the association remains indeterminate due to the insufficient evidence.

Endometrial receptivity and pregnancy outcome

Human implantation is a highly complex and multifactorial process. Successful implantation requires the presence of a healthy embryo, a receptive endometrium, and a synchronized molecular dialogue between the two, as well as immune tolerance/protection from the host. The endometrial receptivity refers to a hormonally limited period in which the endometrial tissue acquires a transient functional status allowing blastocyst implantation and pregnancy initiation. Global knowledge of endometrial receptivity grew up in recent years. Improvements in genetics, new biomarkers, noninvasive methods, new advanced techniques (Endometrial receptivity assay - the ERA system, proteomic analysis) offer the possibility to evaluate the endometrial status and to manage patients with infertility problems, especially women undergoing assisted reproductive treatment. This overview reports the most relevant knowledge and recent advances in the study of implantation processes from the perspective of the endometrium, often considered as being the main barrier for a successful pregnancy initiation. Endometrial receptivity is a topic of great interest and further studies are needed for the early identification of endometrial abnormalities and the discovery of new strategies for increasing the chance for the establishment of pregnancy.

Association of CYP11B2 gene polymorphism with preeclampsia in north east of Iran (Khorasan province)

PURPOSE

Identification the genetic factors in preeclampsia (PE) are useful to increase the current knowledge of the pathophysiology of the disorder. The genetic factors implicated for all cases of PE remain to be determined. This study was aimed to investigate association between ADD1 1378G > T, AGTR2 1675G > A, AGTR1 1166A > C, NOS3 894 G > T and CYP11B2 -344C > T gene polymorphisms in Iranian women with PE.

MATERIAL AND METHODS

117 pregnant women with PE and 103 healthy women without affected previous pregnancy by PE were selected. Genomic DNA was extracted from peripheral blood and real-time PCR was performed to investigate the polymorphisms using a commercial kit.

RESULTS

There was a significant difference in CYP11B2 -344C > T gene polymorphism between case and control groups (P = 0.025). The odds ratio was 0.71 (CI 95% = 0.28-1.79). There were no statistical significant differences between other genetic polymorphisms.

CONCLUSION

Our results showed a significant association between CYP11B2 -344C > T gene polymorphism with PE. This finding suggests that mentioned polymorphism may be associated with susceptibility to PE at least in IRAN.

T lymphocytes in the third trimester decidua in preeclampsia

OBJECTIVE

The aim of study was to conduct immunohistochemical quantification of CD3+ and CD8+ decidual lymphocytes in preeclampsia.

METHODS

A study group included 30 cases of preeclampsia and a control group included 20 healthy pregnant women, all delivered by Cesarean section. Samples of placental bed were analyzed after immunohistochemical staining of CD45+, CD3+ and CD8+ cells.

RESULTS

The group with preeclampsia included a significantly higher number of CD3+ (p < 0.01) and CD8+ (p < 0.05) T lymphocytes.

CONCLUSION

It is certain that thebalance dysregulation of T cell of the immune milieu of deciduais of importance in etiopathogenesis and manifestations of preeclampsia.

Evidence for a role for the adaptive immune response in human term parturition

PROBLEM

Spontaneous labor at term involves leukocyte recruitment and infiltration into the choriodecidua; yet, characterization of these leukocytes and their immunological mediators is incomplete. The purpose of this study was to characterize the immunophenotype of choriodecidual leukocytes as well as the expression of inflammatory mediators in human spontaneous parturition at term.

METHOD OF STUDY

Choriodecidual leukocytes were analyzed by FACS, immunohistochemistry, and RT-PCR in three different groups: (i) preterm gestation delivered for medical indications without labor; (ii) term pregnancy without labor; and (iii) term pregnancy after spontaneous labor.

RESULTS

Two T-cell subsets of memory-like T cells (CD3(+) CD4(+) CD45RO(+) and CD3(+) CD4(-) CD8(-) CD45RO(+) cells) were identified in the choriodecidua of women who had spontaneous labor. Evidence for an extensive immune signaling network composed of chemokines (CXCL8 and CXCL10), chemokine receptors (CXCR1-3), cytokines (IL-1β and TNF-α), cell adhesion molecules, and MMP-9 was identified in these cells during spontaneous labor at term.

CONCLUSIONS

The influx of memory-like T cells in the choriodecidua and the evidence that they are active by producing chemokines and cytokines, and expressing chemokine receptors, cell adhesion molecules, and a matrix-degrading enzyme provides support for the participation of the adaptive immune system in the mechanisms of spontaneous parturition at term.

Expression of endometrial immune-related genes possibly functioning during early pregnancy in the mare

Despite enormous efforts, biochemical and molecular mechanisms associated with equine reproduction, particularly processes of pregnancy establishment, have not been well characterized. Previously, PCR-selected suppression subtraction hybridization analysis was executed to identify unique molecules functioning in the equine endometrium during periods of pregnancy establishment, and granzyme B (GZMB) cDNA was found in the pregnant endometrial cDNA library. Because GZMB is produced from natural killer (NK) cells, endometrial expression of GZMB and immune-related transcripts were characterized in this study. The level of GZMB mRNA is higher in the pregnant endometrium than in non-pregnant ones. This expression was also confirmed through Western blot and immunohistochemical analyses. IL-2 mRNA declined as pregnancy progressed, while IL-15, IFNG and TGFB1 transcripts increased on day 19 and/or 25. Analyses of IL-4 and IL-12 mRNAs demonstrated the increase in these transcripts as pregnancy progressed. Increase in CCR5 and CCR4 mRNAs indicated that both Th1 and Th2 cells coexisted in the day 25 pregnant endometrium. Taken together, the endometrial expression of immune-related transcripts suggests that immunological responses are present even before the trophectoderm actually attaches to the uterine epithelial cells.

Immunological and biochemical markers in preeclampsia

A basic precondition for the development of preeclampsia is the presence of placental trophoblast cells in the maternal blood circulation. On the other hand, while trophoblast cells are present in the blood of all pregnant women, preeclampsia occurs in only 2-5% of them. Evidently, other factors play a crucial role. The aim of this study was to compare a set of selected immunological factors (anti-cardiolipin autoantibodies, trophoblast-induced cell-mediated immunity, C3 and C4 complement components) and biochemical factors (serum immunoglobulins IgA, IgG, IgM) among three groups of women with uncomplicated pregnancy, gestational hypertension, or preeclampsia. Blood samples were taken 2-12h before delivery. In the preeclampsia group, there was a significantly higher number of women positive for anti-cardiolipin autoantibodies, trophoblast-induced cell-mediated immunity was elevated, serum IgG was elevated and C4 complement component was reduced. We conclude that both elevated autoimmune reactivity and the higher immune reactivity to trophoblast may contribute to the onset of preeclampsia.

The immunomodulatory effects of Ipomoea carnea in rats vary depending on life stage

Ipomoea carnea Jacq. ssp. fistulosa (Mart. Ex Choisy; Convolvulaceae; I. carnea) possesses a toxic component: an indolizidine alkaloid swainsonine (SW) that has immunomodulatory effects due to its inhibition of glycoprotein metabolism. It is also known that SW is excreted into both the amniotic fluid and milk of female rats exposed to I. carnea. Thus, the aim of this study was to determine whether SW exposure, either in utero or from the milk of dams treated with I. carnea, modulates offspring immune function into adulthood. In addition, adult (70 days old) and juvenile rats (21 days old) were exposed to I. carnea in order to evaluate several other immune parameters: lymphoid organs relative weight and cellularity, humoral and cellular immune responses. Offspring exposed to I. carnea during lactation developed rheumatoid arthritis (RA) in adulthood after an immunogenic challenge. In addition, both adult and juvenile rats exposed to I. carnea showed discrepancies in several immune parameters, but did not exhibit any decrease in humoral immune response, which was enhanced at both ages. These findings indicate that SW modulates immune function in adult rats exposed to SW during lactation and in juvenile and adult rats exposed to SW as juveniles and adults, respectively.

Interleukin-18 concentrations in pregnancies complicated by preeclampsia with and without IUGR: A comparison with normotensive pregnant women with isolated IUGR and healthy pregnant women

OBJECTIVE

The aim of present study was to assess the maternal serum levels and clinical significance of interleukin-18 (IL-18) in pregnancies complicated by preeclampsia and/or intrauterine growth restriction (IUGR).

PATIENTS AND METHODS

The study was carried out on 30 patients with pregnancy complicated by severe preeclampsia (15 patients with IUGR and 15 with appropriate-for-gestational-age weight fetuses), 11 normotensive pregnant patients with pregnancy complicated by isolated IUGR and 32 healthy normotensive women with uncomplicated pregnancies. The interleukin-18 levels were determined using an ELISA assay.

RESULTS

Decreased levels of maternal serum IL-18 in preeclamptic patients with and without IUGR were observed. Contrary to the preeclamptic women, no difference was found in the maternal serum levels of IL-18 in normotensive patients with pregnancies complicated by isolated fetal growth restriction. These levels were the same as observed in the healthy controls. The mean values of maternal serum IL-18 were 219.118±180.079pg/mL in the PRE group, 438.170±229.657pg/mL in the group of women with isolated IUGR, and 457.053±528.142pg/mL in the control group. The levels of maternal serum IL-18 were similar in both study preeclamptic subgroups. The mean values of IL-18 were 204.823±188.171pg/mL in the group PI and 233.414±176.995pg/mL in the P group.

CONCLUSIONS

Our findings suggest that decreased levels of IL-18 in maternal serum play a significant role in etiology and pathogenesis of preeclampsia. But normotensive pregnancies complicated by isolated IUGR are not associated with the altered interleukin 18 levels in maternal serum.

Fetal rejection: infertility and immunity

Defective reaction toward fetal alloantigens could result in both recurrent spontaneous abortions (RSAs) and recurrent early pregnancy failures (REPFs), the latter existing in couples with unexplained infertility and multiple failures of implantation after in vitro fertilization embryo transfer. Immunological mechanisms leading to RSA and REPF seem to be different, although both syndromes probably have a genetic background that has not been identified so far. Despite the fact that antiphospholipid syndrome is a well-established cause of repeated pregnancy loss, the role of different autoantibodies existing in RSA and REPF patients needs to be elucidated. Immunotherapy is believed to correct the detrimental immune reactions; however, its real effectiveness and safety for the treatment of distinct forms of pregnancy loss need to be reconsidered.

Intake of vitamin C and E in pregnancy and risk of pre-eclampsia: prospective study among 57 346 women

OBJECTIVE

It has been suggested that vitamin C, alone or in combination with vitamin E, may protect against pre-eclampsia, whereas the safety of high-dose vitamin E supplements has been questioned. We investigated dietary intakes of vitamins C and E to see if they correlated with the incidence of pre-eclampsia.

DESIGN

Prospective cohort study.

SETTING

The Danish National Birth Cohort; a population-based pregnancy cohort; analyses were based on 57 346 pregnancies.

METHODS

Vitamin intake was estimated from a food frequency questionnaire completed in gestational week 25, recording intake from diet and supplements during the previous four weeks. Pre-eclampsia diagnoses were obtained from the Danish National Patient Registry; we worked with two entities, 'pre-eclampsia (all types)' and 'severe pre-eclampsia/eclampsia/HELLP'. We adjusted for confounding factors by logistic regression.

MAIN OUTCOME MEASURES

A small increase in the incidence of severe disease was also seen in the group of women (64, n = 49 373) with a high intake of vitamin E from supplements and dietary sources.

RESULTS

The incidence of 'pre-eclampsia (all types)' did not correlate with dietary vitamin C and E intake. There was a decreasing trend (P = 0.01) in the incidence of 'severe pre-eclampsia/eclampsia/HELLP' with increasing dietary vitamin C intake; with an intake of 130-170 mg/day as reference, odds ratios ranged from 1.21 (95% confidence interval 0.83 to 1.75) for an intake below 70 mg/day to 0.70 (0.40 to 1.23) for an intake exceeding 275 mg/day (total n = 57 346). For vitamin E intake aggregated from diet and supplements (n = 49 373), with an intake of 10.5-13.5 mg/day as reference, the 'severe pre-eclampsia/eclampsia/HELLP' odds ratio was 1.46 (1.02 to 2.09) for an intake exceeding 18 mg/day.

CONCLUSIONS

Low dietary intake of vitamin C was associated with a trend towards an increased incidence of either severe pre-eclampsia, eclampsia or HELLP. A small increase in the incidence of severe disease was also seen in the group of women with a high intake of vitamin E from supplements and dietary sources.

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.

Mouse model for allogeneic immune reaction against fetus recapitulates human pre-eclampsia

AIM

We have previously demonstrated that mRNA expression and enzyme activity levels of placental indoleamine 2,3-dioxygenase (IDO), which degrades L-tryptophan and blocks the proliferation of T cells, are significantly low in patients with severe pre-eclampsia. From this observation, we hypothesized that induction of maternal allogeneic immune reaction by reduced IDO activity is one of the causes of pre-eclampsia.

METHODS

To examine this hypothesis, we administered an IDO inhibitor to pregnant female mice carrying allogeneic concepti. Since administration of an IDO inhibitor to pregnant mice starting at E4.5 is already reported to cause allogeneic fetal rejection, we modified the regimen and started the administration at E6.5 when the fetus and placenta have already been established.

RESULTS

Pregnant mice treated with an IDO inhibitor developed high blood pressure and proteinuria in addition to local circulation impairment in the placenta, which is analogous to the lesions that are characteristic of human pre-eclampsia. In contrast, pregnant mice carrying syngeneic concepti did not manifest such symptoms.

CONCLUSIONS

Our findings reveal a pivotal role for IDO activity in the etiology of pre-eclampsia. These data also lend support to the current hypothesis that pre-eclampsia is one of the possible manifestations of a maternal immunological reaction against an allogeneic fetus.

Inadequate tolerance induction may induce pre-eclampsia

The fetus is semi-allograft to the maternal host; therefore, a system of tolerance must be present during pregnancy. Epidemiological findings support a relationship between pre-eclampsia and the failure of tolerance induction. For induction of major histocompatibility complex (MHC) class I-specific tolerance, long-term exposure to seminal fluid, which contains paternal soluble MHC class I antigens, may induce paternal MHC class I-specific tolerance. Furthermore, soluble HLA-G1, which induces the deletion of CD8(+) T-cells, and the combination of maternal killer-immunoglobulin-like receptors (KIR) on NK cells and fetal HLA-C, which affects the balance between inhibition and activation signals of NK cells, regulatory CD8(+) T cells, and regulatory NK cells, may play very important roles in the induction of MHC class I-specific tolerance. On the other hand, exposure to sperm, which express paternal HLA-DR, and trophoblastic debris, which contain intracellular fetal HLA-DR, may induce paternal MHC class II-specific tolerance. In this process, CD4(+)CD25(+) regulatory T (Treg)-cells play central roles. In this review, we discuss the relationship between the risk of pre-eclampsia and tolerance induction.

RCAS1 decidual immunoreactivity in severe pre-eclampsia: immune cell presence and activity

PROBLEM

Pre-eclampsia seems to be related to the disturbance of immune tolerance regulation during pregnancy. Receptor-binding cancer antigen expressed on SiSo cells (RCAS1) decidual level alterations were concomitant with changes in immune cell number and activity in decidua. As decidual immunomodulating activity participates in the development of immune tolerance during pregnancy, we aimed to evaluate the immunoreactivity level of decidual RCAS1 with respect to the presence and activity of immune cells.

METHOD OF STUDY

RCAS1, CD3, CD56, CD69, and CD25 immunoreactivity was assessed by immunohistochemistry in 30 decidual samples derived from patients with severe pre-eclampsia (sPE) and from a healthy control group.

RESULTS

RCAS1 immunoreactivity was statistically significantly higher in decidual tissue samples derived from patients with sPE tissue than in those derived from healthy patients in whom elective cesarean section at term was performed. A statistically significantly lower number of CD56(+) and CD3(+) cells and lower immunoreactivity level of CD69 were found in patients with sPE compared with those from the control group.

CONCLUSION

The limited immune cells infiltration in decidua during sPE is associated with increase in RCAS1 decidual level.

The etiological role of allogeneic fetal rejection in pre-eclampsia

PROBLEM

It has been demonstrated that allogeneic fetal rejection in normal pregnancy is prevented by placental indoleamine 2,3-dioxygenase (IDO). Further, an immunological etiology has been implicated in pre-eclampsia.

METHOD OF STUDY

We examined the differences in placental IDO activity between normal and pre-eclamptic pregnancies.

RESULTS

IDO mRNA expression and enzyme activity levels in the placenta were low in patients with severe pre-eclampsia. The enzyme activity also inversely correlates with the blood pressure of the patients. In the placentas from severe pre-eclampsia, IDO immunoreactivity was low, whereas regional T-cell infiltration was observed reciprocally proportional to the IDO activity.

CONCLUSION

Our findings implicate a potential role for IDO activity and a maternal immunological reaction against an allogeneic fetus in the etiology of pre-eclampsia.

UNK cells: their role in tissue re-modelling and preeclampsia

In different species of mammal, uterine natural killer (uNK) cells are massively recruited and presented at the fetal maternal interface with a spatio-temporal pattern, and regarded as a constructive element to support reproductive development. Recent insights highlight the uNK cells activation, function and interaction with local compartments, which all contribute to the initiation of vascular structural changes. New trends of uNK cells research will benefit the diagnosis, management and test treatment strategy of preeclampsia. Furthermore, we suggest that more efforts and specific studies are needed to further explore the role of uNK cells at the unique micro-environment.

The role of the immune system in preeclampsia

Recent data demonstrate that an altered immune response may play a key role in the development of preeclampsia. Some epidemiological findings and animal models support this idea. In this article, we review the innate immune system and adaptive immune system in preeclampsia and discuss the pathophysiology of preeclampsia from an immunological viewpoint. The most characteristic immunological finding in preeclampsia is the activation of both the innate and adaptive immune system. Activated neutrophils, monocytes, and NK cells initiate inflammation which induce endothelial dysfunction, and activated T cells may support inadequate tolerance during pregnancy. The cytokine profile in preeclampsia shows that the production of type 1 cytokines, which induce inflammation, is dominant while the production of type 2 cytokines, which regulates inflammation, is suppressed. Furthermore, the immunoregulatory system is down-regulated in preeclampsia and persistent inflammation reduces regulatory T cell function. Therefore, systematical immunoactivation may be one cause of preeclampsia.

Microarray analysis of differentially expressed fetal genes in placental tissue derived from early and late onset severe pre-eclampsia

Although it has been well documented that pre-eclampsia is caused by a combination of maternal and fetal susceptibility genes, little is known about the precise etiology of this complicated disorder. To investigate how the expression of fetal genes contributes to the mechanisms underlying the progression of this disease, we have analyzed differentially expressed genes using placentas from 13 normal pregnancies and 14 pregnancies with severe pre-eclampsia. We performed genome-wide expression profiling using high-density oligonucleotide microarrays, followed by validation using real-time PCR. Among the 47,000 genes that were screened in the microarray, 137 genes were found to be differentially expressed between normal and pre-eclamptic tissues. Among these candidates, 70 were up-regulated and 67 were down-regulated. The up-regulated genes included leptin and inhibin A, which are well-known biological markers for pre-eclampsia, as well as FLT1, which was recently proved to be tightly linked with the etiology of this disease. Gene ontology analysis further revealed several biological processes that could be associated with the development of pre-eclampsia, including response to stress, host-pathogen interactions, lipid metabolism, and carbohydrate metabolism. Analyses of biological mechanisms highlighted some important pathways that may be involved in this disorder, such as the TGF-beta and CEBPA-related pathways. Furthermore, when our present subjects were classified as either severe cases of early onset or late onset pre-eclampsia, the expression of 11 genes could be correlated with the severity of this disorder. These genes may therefore prove to be novel biological markers by which the severity of this condition could be predicted. Our data are likely to be a useful future resource in the elucidation of the disease-process and in the identification of novel markers for pre-eclampsia.

Immunological analogy between allograft rejection, recurrent abortion and pre-eclampsia - the same basic mechanism?

There are still controversies concerning the role of immunological mechanisms engaged both in recurrent abortions (RA) and pre-eclampsia (PE). According to some opinions, recurrent miscarriage is comparable to organ-specific autoimmune disease. Analysis of immune reactions shows that graft rejection shares many similar mechanisms with RA and PE. This fact allows us to conclude that rejection of transplanted alloantigenic organs and pregnancy loss have probably the same evolutionary origin. Subsets and functions of immunocompetent cells (T CD4, suppressor gammadeltaT, cytotoxic T CD8, Treg, Tr1, uterine NK cells), over-activation of innate immunity (activation of NK cytotoxic cells, macrophages, neutrophils and complement), changes of Th1/Th2 cytokine balance (IL-2, IL-12, IL-15, IL-18, IFNgamma, TNFalpha vs. IL-4, IL-10, TGFbeta), importance of HLA-G molecule, CD200/CD200R interaction, over-expression of adhesion molecules, fgl2 prothrombinase activation and stimulation of IDO and HO expression, all suggest that RA and PE are syndromes of fetal allograft rejection, and not organ-specific autoimmune diseases. According to that supposition, an analogy might exist between acute graft rejection and recurrent abortion, and between chronic graft rejection and pre-eclampsia.

The effect of serum from women with preeclampsia on JAR (trophoblast-like) cell line

OBJECTIVE

Pathologic placentation has been implicated in the pathogenesis of preeclamsia. We sought to assess the effect serum obtained from women with preeclampsia would have on JAR human choriocarcinoma cells regarding growth, invasiveness, and matrix metalloproteinase (MMP) secretion as compared to normotensive pregnant woman.

METHODS

Blood was collected from 11 healthy pregnant women and from10 patients with preeclampsia at 28-33 weeks of gestation. The JAR human choriocarcinoma cell line was cultured in the presence of 10% serum obtained from each group. Cell proliferation, invasiveness, and MMP secretion was measured using a cell proliferation kit, the Matrigel (BD Biosciences, Beit-Ha'Emek, Israel) invasion assay, and gel zymography, respectively.

RESULTS

Cell growth increased by 6% when exposed to serum from patients with preeclampsia compared to 30% from controls (P <.01). Trophoblast invasion was significantly (P <.01) reduced in the preeclampsia group (21 +/- 1.9%) compared to controls (27 +/- 2.5%). Valid MMP-2 secretion was reduced by 51% in the preeclampsia group compared to controls (P <.05).

CONCLUSION

Serum obtained from women with preeclampsia contains a factor or factors that exhibit an inhibitory effect on JAR trophoblast cell proliferation, invasiveness, and MMP-2 secretion. These factors may be involved in the pathologic placentation associated with the pathogenesis of preeclampsia.

Fourth International Workshop on immunology of pre-eclampsia, December 2004, Reunion, France

The Fourth International Workshop on 'Reproductive Immunology, Immunological Tolerance and Immunology of Pre-eclampsia' was held in the Island of La Reunion in December 2004. Besides intense sharing of immunological data, it included also epidemiological studies from South Africa, USA and Australia, as well as genetic studies from South Africa and Mauritius, discussions on the future of graft transplant tolerance, implications of inositol-phosphoglycans in the pathogenesis of pre-eclampsia (PE), pathways to the inflammatory syndrome and other topics. Participants shared the belief that we may be witnessing significant steps forward in our comprehension of PE as an immunological event, with a prominent role for deregulation of the innate immune system, probably controlled by T cells and cytokine networks at the feto-placental interface. There was a growing consensus for an NK cell (KIR)-dependent event, with regulation exerted by T cells, as well as an important role for HLA-C presentation/recognition and HLA-G in mediating inflammatory cytokine imbalance, with an emphasis on IL-12 and IL-16 It is hoped that the next Workshop in 2006 will prove the immune involvement by dissecting the NK/Treg/Ts cell and HLA-CI HLA-G circuits leading to cytokine and vascular dysfunction.

Trafficking of peripheral blood CD56(bright) cells to the decidualizing uterus--new tricks for old dogmas?

CD56(bright) lymphocytes become abundant in the human uterus during every menstrual cycle, following the surge in pituitary-derived luteinizing hormone (LH), which initiates final oocyte maturation. While the uterus is host to some CD56(bright) cells prior to ovulation, the rapid increase is thought to be due to proliferation of the resident population, accompanied by recruitment of CD56(bright) lymphocytes from the circulation. The rapid increase in CD56(bright) cells is concurrent with the onset of decidualization, the transformation of uterine stromal cells into secretory decidual cells. Uterine CD56(bright) cells proliferate and differentiate to become the predominant lymphocytes of the post-ovulatory uterus. These distinct, tissue-specific natural killer (NK) cells either die prior to menses or increase in number during early pregnancy, and then decline toward the end of the first trimester. Since lymphocytes home to tissues from the circulation, we investigated mechanisms of NK cell traffic over the course of natural menstrual cycles by measuring functional interactions between CD56+ cells from blood and endothelial cells using the Stamper-Woodruff assay of lymphocyte adhesion to frozen tissue sections. While a baseline level of adhesion was maintained throughout the cycle, elevated l-selectin-dependent adhesion of peripheral blood CD56(bright) cells occurred during a peri-ovulatory window. However, there were no significant menstrual cycle-induced changes in the transcription of l-selectin, alpha 4 integrin or LFA-1, or in expression of these proteins by NK cells, suggesting that the enhanced adhesion was due to post-translational modifications of these molecules. Quantitative RT-PCR failed to amplify the message for LH receptor or the alpha or beta forms of progesterone or estrogen receptors from blood NK cell subsets. Thus, we conclude that the actions of LH, E(2,) and P(4) on NK cells that promote interactions with endothelium and potential uterine homing are indirectly mediated through the responsiveness of other cell types.

Periovulatory increases in tissue homing potential of circulating CD56(bright) cells are associated with fertile menstrual cycles

CD56(bright) lymphocytes appear in the uterus 3-5 d after ovulation coincident with the onset of stromal cell decidualization. Although the source of these uterine immune cells is not defined, a subset of blood CD56(bright) cells exhibits enhanced capacity to adhere to decidual vascular endothelium during the periovulatory period of menstrual cycles. In this study, the effects of early pregnancy on the adhesive capacity of CD56(bright) cells to bind uterine substrates were examined in a time-course study of 18 infertile women undergoing natural cycles before transfer of frozen/thawed embryos and 18 infertile women undergoing controlled ovarian stimulation. There were three pregnancies in the natural cycle group and seven in the hormone-stimulated cohort. Hormone levels, and number and quality of transferred embryos were similar between pregnant and nonpregnant cycles. However, the adhesive function of CD56(bright) cells increased before ovulation in hormone-treated women who became pregnant and before embryo transfer in naturally cycling women who became pregnant. This pattern of incremental adhesion, which was less frequently observed in unsuccessful cycles, suggests a role for NK cells in implantation. These results support the idea that temporal control of NK cell homing to the uterine microenvironment is a prerequisite to pregnancy.

Pre-eclampsia

Pre-eclampsia is a major cause of maternal mortality (15-20% in developed countries) and morbidities (acute and long-term), perinatal deaths, preterm birth, and intrauterine growth restriction. Key findings support a causal or pathogenetic model of superficial placentation driven by immune maladaptation, with subsequently reduced concentrations of angiogenic growth factors and increased placental debris in the maternal circulation resulting in a (mainly hypertensive) maternal inflammatory response. The final phenotype, maternal pre-eclamptic syndrome, is further modulated by pre-existing maternal cardiovascular or metabolic fitness. Currently, women at risk are identified on the basis of epidemiological and clinical risk factors, but the diagnostic criteria of pre-eclampsia remain unclear, with no known biomarkers. Treatment is still prenatal care, timely diagnosis, proper management, and timely delivery. Many interventions to lengthen pregnancy (eg, treatment for mild hypertension, plasma-volume expansion, and corticosteroid use) have a poor evidence base. We review findings on the diagnosis, risk factors, and pathogenesis of pre-eclampsia and the present status of its prediction, prevention, and management.

[Secreted cytokines in the uterine lumina are predictive of subsequent implantation. Presence of IL18 in the uterine flushing]

The materno-foetal relationship is not simply maternal tolerance of a foreign tissue, but a series of intricate mutual cytokine interactions governing selective immune regulation and also control of the adhesion and vascularisation processes during this dialogue. There is strong evidence that locally secreted cytokines, such as interleukine 18 (IL18) control the implantation process and can cause implantation failure in case of absence or overactivation. Uterine flushing fluids may be analysed to determine the level of several cytokines. At the time of egg retrieval, the flushing procedure does not adversely affect pregnancy rates. We report a strong positive correlation between the presence of IL18 in the uterine flushing and bad implantation rates. The presence of IL18 in the lumina is the traduction of an overactivation of endometrial IL18 that should be diagnosed and treated. Moreover, endometrial biopsy could define which type of cytokinic dysregulation is implicated in repeated implantation failure and define which type of treatment need to be introduced.