An increase of Treg cells in the peripheral blood is associated with a better in vitro fertilization treatment outcome

The Causal Relationship Between Immune Cells and Infertility: A Mendelian Randomisation Study

OBJECTIVE

Infertility has emerged as a significant global public health concern, with a multitude of complex underlying causes. Epidemiological evidence indicates that immunological factors are significant contributors to the aetiology of infertility. However, previous studies on the relationship between immune inflammation and infertility have yielded inconclusive results.

METHODS

Mendelian randomisation (MR) is an emerging statistical method that employs exposure-related genetic variation as an instrumental variable (IV) to infer causal relationships between immune cells and infertility by modelling the principle of random assignment in Mendelian genetics. In this study, MR was employed to assess the causal relationship between 731 immune cell signatures and infertility. The data utilized in this study were obtained from publicly available genome-wide association studies (GWAS) and validated IVs, which were employed to fulfil the essential assumptions of MR analysis.

RESULTS

The Mendelian randomisation analysis revealed a total of 27 statistically significant immune cell phenotypes out of 731. The risk factor with the largest odds ratio (OR) was CD28- CD25++ CD8+ %T cell [OR, 1.21; 95% confidence interval (CI), 1.04-1.42], while the protective factor with the largest OR was activated and resting Treg AC (OR, 0.89; 95% CI, 0.82-0.97).

CONCLUSION

The present study has demonstrated a correlation between certain characteristics of immune cells and female infertility. These results provide clues for further research into the immune mechanisms of infertility and may inform the development of novel therapeutic strategies.

Innate and adaptive immune dysregulation in women with recurrent implantation failure

Recurrent implantation failure (RIF) is a condition where a woman fails to obtain pregnancy after multiple embryo transfer cycles, even with superior-quality blastocysts. There are various factors that can contribute to RIF, including immunologic disturbances. The immune system is extremely important during pregnancy. Immune cells such as T cells, B cells, natural killer (NK) cells, and macrophages (MQ) are present in the female reproductive tract and are accountable for regulating the immune response to invading pathogens and maintaining tissue homeostasis. Dysregulation of these immune cells can lead to inflammation, which can impair fertility. One of the most common immunological disturbances observed in RIF is an altered Th1/Th2 ratio, along with changes in NK cell and macrophage numbers. In addition, the presence of some antibodies, such as anti-ovarian antibodies, can also contribute to RIF. Interleukins have been implicated in the development of an inflammatory response that can interfere with successful embryo implantation. As a result, a comprehensive understanding of immunological compartments in RIF women could assist us in determining the immunological origins of this disease. We will discuss immunological factors that might contribute to RIF etiology, including cellular and molecular components.

Immune system cells modulation in patients with reproductive issues: A systematic review approach

The aim of this study was to carry out a systematic literature review to investigate the main immune cells responsible for implantation failures. We selected papers from PubMed, Embase and Virtual Health Library databases. Eligible articles included publications between January 1, 2010 and April 24, 2022. Inclusion criteria were: observational and case-control studies; and the exclusion criteria were: review papers, letters to the editor, abstracts, animal studies and case reports. We extracted the following information: day of collection, number of patients, control group, age of patients, type of sample used, immune cells and cytokines. As main findings in our mapping, we found that in peripheral blood, CD3+, CD4+, CD8+, CD16+, CD56+, CD57+, CD69+, CD154+, CD158a+, NKp46 cells were increased and the CD4+, CD45+, Foxp3 and NKp46 markers were reduced. From the endometrial biopsies, there was an increase in CD3+, CD4+, CD5+, CD8+, CD16+, CD25+, CD45+, CD56+, CD57+, CD68+, CD127+ and a reduction in CD45+, CD56+, NKp46 and FoxP3 cells. Cytokines found increased in peripheral blood included IL-6, IL-10, IL-17, INF-γ, TGF-ß, TNF-α; while IL-4, IL-6, IL-10, IL-35, FoxP3, TGF-ß, SOCS3 were reduced. As for the biopsies, there was an increase in IL-2, IL-6, IL-17, IL-22, IL-23, INF-A1, INF-B1, INF-γ, TNF-R and a reduction in IL-6, IL-10, INF-γ, TGFß, TNF-α. We concluded that immune cells can be modulated during pregnancy failure, but further studies are needed to elucidate the modulating effect of the immune system on the endometrium of these patients.

Immunobiology of pregnancy: from basic science to translational medicine

Embryo implantation failure and spontaneous abortions represent the main causes of infertility in developed countries. Unfortunately, incomplete knowledge of the multiple factors involved in implantation and fetal development keeps the success rate of medically assisted procreation techniques relatively low. According to recent literature, cellular and molecular mechanisms of 'immunogenic tolerance' towards the embryo are crucial to establish an 'anti-inflammatory' state permissive of a healthy pregnancy. In this review we dissect the role played by the immune system in the endometrial-embryo crosstalk, with a particular emphasis towards the fork-head-box-p3 (Foxp3+) CD4+CD25+ regulatory T (Treg) cells and discuss the most recent therapeutic advances in the context of early immune-mediated pregnancy loss.

Modification of peripheric Treg and CD56brightNK levels in RIF women after egg donation, treated with GM-CSF or placebo

Recurrent implantation failure (RIF) is defined as when implantation repeatedly failed to reach a stage recognizable by pelvic ultrasound in IVF cycle and it may be due to several causes. The GM-CSF is a cytokine promoting leukocyte growth and trophoblast development: we tested it to treat these patients in a pilot-controlled trial evaluating the modification of peripheric Treg and CD56brightNK levels after the treatment with this cytokine and in control patients affected by RIF after egg donation cycles. This study was performed on 24 RIF women after egg donation cycles. Single good quality blastocyst transfer was performed in the cycle object of this study. Patients were randomly assigned to two groups: 12 women treated with subcutaneous GM-CSF 0.3 mg/kg/daily from the day before embryo transfer to the β-hCG day, and 12 women treated with subcutaneous saline solution infusion as control. All patients were tested for Treg and CD56brightNK cell levels in blood circulation before and after treatment using flow-cytometry with specific antibodies. The two groups of patients were similar for epidemiologic characteristics, the ongoing pregnancy rate in the GM-CSF group was 83.3% whereas in the control group was 25.0% (P = 0.0123). In the study group there was a significative increase of Treg cells (P < 0.001) with respect to the levels before treatment and to control group. Instead, the levels of CD56brightNK did not show any significative variation. Our study showed that the treatment with GM-CSF increases the Treg cells in the peripheric blood.

MDSCs in pregnancy and pregnancy-related complications: an update†

Maternal-fetal immune tolerance is a process that involves complex interactions of the immune system, and myeloid-derived suppressor cells have emerged as one of the novel immunomodulator in the maintenance of maternal-fetal immune tolerance. Myeloid-derived suppressor cells are myeloid progenitor cells with immunosuppressive activities on both innate and adaptive cells through various mechanisms. Emerging evidence demonstrates the accumulation of myeloid-derived suppressor cells during healthy pregnancy to establish maternal-fetal immune tolerance, placentation, and fetal-growth process. By contrast, the absence or decreased myeloid-derived suppressor cells in pregnancy complications like preeclampsia, preterm birth, stillbirth, and recurrent spontaneous abortion have been reported. Here, we have summarized the origin, mechanisms, and functions of myeloid-derived suppressor cells during pregnancy along with the recent advancements in this dynamic field. We also shed light on the immunomodulatory activity of myeloid-derived suppressor cells, which can be a foundation for potential therapeutic manipulation in immunological pregnancy complications.

Profiling of Immunomodulatory Genes and Quantification of CD25+ Cells in Different Types of Early Pregnancy Loss

INTRODUCTION

Maternal regulatory T (Treg) cells play a pivotal role in establishing general immune homeostasis in the decidua for maintenance of pregnancy. We aimed in this study to investigate the relationship between mRNA expression of immunomodulatory genes and CD25+ Treg cells with early pregnancy losses.

METHODS

Our study included 3 groups of early pregnancy losses including sporadic spontaneous abortions, recurrent spontaneous abortions, sporadic spontaneous abortions post IVF treatment and the control group. We performed RT-PCR for analyzing mRNA expression levels of 6 immunomodulatory genes and CD25 immunohistochemistry for quantification of Treg cells.

RESULTS

Only FOXP3, CD274 (PDL1), and TGFβ1 mRNA expression levels were significantly decreased in the miscarriage groups in comparison to the control group, whereas there was no significant mRNA expression change of CD4, IL2RA, and IL10. We also found significantly lower number of CD25+ cells in the miscarriages.

CONCLUSION

We conclude that decreased expression of FOXP3 and PD-L1 may play a significant role in the pathogenesis of spontaneous abortion cases whereas decreased expression of TGFβ1 gene may be associated with the occurrence of early loss in IVF-treated pregnancies. Additional immunoprofiling of Treg cell population is needed to quantify Treg cells in early pregnancy losses.

Dominant immune cells in pregnancy and pregnancy complications: T helper cells (TH1/TH2, TH17/Treg cells), NK cells, MDSCs, and the immune checkpoints

Pregnancy problems including recurrent pregnancy loss, repeated implantation failure and pre-eclampsia  are common problems in the reproductive ages. Different reasons such as genetic, immunological, and environmental agents and also infections could develop these complications. In those cases in which the cause of the abortion is diagnosed, the chance of a successful pregnancy is increased by eliminating defective factors. However, in patients with unknown causes, there may be an imbalance in immune cells pattern. As a matter of fact, an inappropriate immune response is often associated with a failed pregnancy. Hence, the focus of treatment is to increase tolerance, not to suppress maternal immune system. These findings are linked to an elevated number of Treg cells and immune checkpoints through normal pregnancy. The present review discusses the balance of myeloid-derived suppressor cells, natural killer cells, T cells, and immune checkpoints, and also targeting them to maintain pregnancy and prevent associated complications.

Immune checkpoint inhibitors and reproductive failures

The human conceptus is a semi-allograft, which is antigenically foreign to the mother. Hence, the implantation process needs mechanisms to prevent allograft rejection during successful pregnancy. Immune checkpoints are a group of inhibitory pathways expressed on the surface of various immune cells in the form of ligand receptors. Immune cells possess these pathways to regulate the magnitude of immune responses and induce maternal-fetal tolerance. Briefly, 1) CTLA-4 can weaken T cell receptor (TCR) signals and inhibit T cell response; 2) The PD-1/PD-L1 pathway can reduce T cell proliferation, enhance T cell anergy and fatigue, reduce cytokine production, and increase T regulatory cell activity to complete the immunosuppression; 3) TIM3 interacts with T cells by binding Gal-9, weakening Th1 cell-mediated immunity and T cell apoptosis; 4) The LAG-3 binding to MHC II can inhibit T cell activation by interfering with the binding of CD4 to MHC II, and; 5) TIGIT can release inhibitory signals to NK and T cells through the ITIM structure of its cytoplasmic tail. Therefore, dysregulated immune checkpoints or the application of immune checkpoint inhibitors may impair human reproduction. This review intends to deliver a comprehensive overview of immune checkpoints in pregnancy, including CTLA-4, PD-1/PD-L1, TIM-3, LAG-3, TIGIT, and their inhibitors, reviewing their roles in normal and pathological human pregnancies.

Decreased ratio of FOXP3+/FOXP3-CD45RA+CD4+ T cells in peripheral blood is associated with unexplained infertility and ART failure

Unexplained infertility has a huge social impact and is a significant challenge for both clinicians and researchers. Previous studies have shown the involvement of multiple factors in infertility. Among these, the subset of regulatory T cells is of particular interest for the maternal tolerance towards the semi-allogenic fetus. We investigated circulating CD45RA⁺ regulatory and non-regulatory CD4⁺ T cells in healthy women and patients with unexplained infertility in the context of thymic output and peripheral proliferation. The proportion of FOXP3⁺ and FOXP3^-CD45RA⁺CD4⁺ T cells in peripheral blood was studied in control groups of healthy parous and nulliparous (never-pregnant) women and in patients with unexplained infertility. In the same groups thymic output and peripheral proliferation were defined by the sj/βTREC ratio, and signal joint T-cell receptor excision circles (sjTREC) and Ki67 expression, respectively. In parous women a decrease in sjTREC/10⁵ cells and CD45RA⁺ T lymphocytes, compared to nulliparous group was found. At the same time, the proportion of FOXP3^-CD45RA⁺CD4⁺ cells, but not FOXP3⁺CD45RA⁺ Tregs was reduced. In contrast, in patients with unsuccessful pregnancy, proportions of both regulatory and non-regulatory T cell counterparts were lower. Taken together, our results provide evidence for group-specific properties in the CD45RA⁺ T cell compartment between healthy parous, nulliparous and women with unexplained infertility.

Endometrium Immunomodulation to Prevent Recurrent Implantation Failure in Assisted Reproductive Technology

After more than four decades of assisted reproductive technology (ART) practice worldwide, today more than 60% of women undergoing in vitro fertilization (IVF) treatments fail to become pregnant after the first embryo transfer and nearly 20% of patients are suffering from unexplained recurrent implantation failures (RIFs) and repeated pregnancy loss (RPL). The literature reported different causes of RIF–RPL, mainly multifactorial, endometrial and idiopathic. RIF remains a black box because of the complicated categorization and causes of this physio-pathological dysregulation of implantation and pregnancy process after ovarian stimulation. Many options were suggested as solutions to treat RIF–RPL with controversial results on their usefulness. In this article, we reviewed different possible therapeutic options to improve implantation rates and clinical outcomes. Based on our experience we believe that endometrium immunomodulation after intrauterine insemination of activated autologous peripheral blood mononuclear cells (PBMCs) or platelet-rich plasma (PRP) can be a promising therapeutic solution. On the other hand, peripheral lymphocyte balance typing, specific cytokines and interleukins profiling can be proposed as predictive biomarkers of implantation before embryo transfer.

Role of hormones in the pregnancy and sex-specific outcomes to infections with respiratory viruses

Pregnant women infected with pathogenic respiratory viruses, such as influenza A viruses (IAV) and coronaviruses, are at higher risk for mortality, hospitalization, preterm birth, and stillbirth. Several factors are likely to contribute to the susceptibility of pregnant individuals to severe lung disease including changes in pulmonary physiology, immune defenses, and effector functions of some immune cells. Pregnancy is also a physiologic state characterized by higher levels of multiple hormones that may impact the effector functions of immune cells, such as progesterone, estrogen, human chorionic gonadotropin, prolactin, and relaxin. Each of these hormones acts to support a tolerogenic immune state of pregnancy, which helps prevent fetal rejection, but may also contribute to an impaired antiviral response. In this review, we address the unique role of adaptive and innate immune cells in the control of pathogenic respiratory viruses and how pregnancy and specific hormones can impact their effector actions. We highlight viruses with sex-specific differences in infection outcomes and why pregnancy hormones may contribute to fetal protection but aid the virus at the expense of the mother's health.

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.

Recurrent Implantation Failure May Be Identified by a Combination of Diagnostic Biomarkers: An Analysis of Peripheral Blood Lymphocyte Subsets

BACKGROUND

Recurrent implantation failure (RIF) is a challenge during assisted reproductive technology (ART). In the present study, potential diagnostic biomarkers for the immune status of peripheral blood lymphocyte subsets in patients with RIF were analyzed, with the aim of identifying novel biomarkers that may predict RIF.

METHODS

A total of 41 participants, including 21 women with RIF and 20 fertile controls, were included in the present study. Functional analysis was performed and the cytokine status of natural killer (NK), T, CD8+ T, T helper (Th), and γδ T cells which are lymphocyte subsets in peripheral blood was measured using flow cytometry. Binary logistic regression analysis adjusted for T follicular helper 1 (Tfh1), Tfh2, Tfh17, and early NK cells was performed to determine the relationship between the peripheral blood lymphocyte subsets and RIF. Potential diagnostic biomarkers were assessed by logistic regression analysis and receiver operating characteristic curves.

RESULTS

There were significantly more Tfh1, Tfh17, and NK cells in the RIF group compared with the control group (all P < 0.05). However, the percentage of T, regulatory T (Tregs), and Tfh2 cells, as well as early inhibitory NK cells, was significantly lower in the RIF group compared with the control group (all P < 0.05). Following logistics regression analysis, Treg, Tfh17, and early inhibitory NK cells exhibited significant differences between the two groups. Combination diagnosis using these 3 biomarkers had a higher area under the curve of 0.900 (95% confidence interval: 0.808-0.992, P < 0.001) in the RIF group compared with that in the control group.

CONCLUSION

T, Tregs, Tfh1, Tfh2, Tfh17, NK cells, and early inhibitory NK cells may play important regulatory roles in embryo implantation. The combination of 3 molecular markers (Treg, Tfh17, and early inhibitory NK cells) could provide a high diagnostic value for women with RIF, thus providing novel potential biomarkers for RIF in ART. The present findings could provide a reference either for the clinical treatment of patients with RIF or for future large, well-designed studies.

Endometrial Microbiome and Women’s Reproductive Health – Review of the Problem Endometrial Microbiome and Reproductive Health

Currently, unlike in the past, the endometrial cavity is not considered to be sterile. The endometrium is supposed to be dominated by Lactobacilli, but also their deficiency can be found in the reproductive tract of asymptomatic healthy women. Sometimes the endometrial microbiome is dominated by various pathological microorganisms, and this can lead to various conditions as chronic endometritis, chorioamnionitis and preterm birth. Their presence causes uterine inflammation and infection, release of pro-inflammatory molecules, uterine contractions, disruption of cervical barrier, premature rupture of membranes. Uterine dysbiosis is associated with recurrent implantation failure and recurrent miscarriages. As the microbiome is important for maintaining immunological homeostasis at the level of gastrointestinal tract Lactobacilli may play a similar function at the level of uterus. The lactobacillus-dominated uterine microbiome is of great importance for maintaining a hostile uterine microenvironment, embryo implantation, early pregnancy development and normal pregnancy outcome.

Human Chorionic Gonadotropin and Related Peptides: Candidate Anti-Inflammatory Therapy in Early Stages of Sepsis

Sepsis continues to be a major cause of morbidity, mortality, and post-recovery disability in patients with a wide range of non-infectious and infectious inflammatory disorders, including COVID-19. The clinical onset of sepsis is often marked by the explosive release into the extracellular fluids of a multiplicity of host-derived cytokines and other pro-inflammatory hormone-like messengers from endogenous sources ("cytokine storm"). In patients with sepsis, therapies to counter the pro-inflammatory torrent, even when administered early, typically fall short. The major focus of our proposed essay is to promote pre-clinical studies with hCG (human chorionic gonadotropin) as a potential anti-inflammatory therapy for sepsis.

Effect of Intralipid infusion on peripheral blood T cells and plasma cytokines in women undergoing assisted reproduction treatment

Objectives

Intravenous infusion of Intralipid is an adjunct therapy in assisted reproduction treatment (ART) when immune‐associated infertility is suspected. Here, we evaluated the effect of Intralipid infusion on regulatory T cells (Treg cells), effector T cells and plasma cytokines in peripheral blood of women undertaking IVF.

Methods

This prospective, observational pilot study assessed Intralipid infusion in 14 women exhibiting recurrent implantation failure, a clinical sign of immune‐associated infertility. Peripheral blood was collected immediately prior to and 7 days after intravenous administration of Intralipid. Plasma cytokines were measured by Luminex, and T‐cell subsets were analysed by flow cytometry.

Results

A small increase in conventional CD8⁺ T cells occurred after Intralipid infusion, but no change was seen in CD4⁺ Treg cells, or naïve, memory or effector memory T cells. Proliferation marker Ki67, transcription factors Tbet and RORγt, and markers of suppressive capacity CTLA4 and HLA‐DR were unchanged. Dimensionality‐reduction analysis using the tSNE algorithm confirmed no phenotype shift within Treg cells or other T cells. Intralipid infusion increased plasma CCL2, CCL3, CXCL8, GM‐CSF, G‐CSF, IL‐6, IL‐21, TNF and VEGF.

Conclusion

Intralipid infusion elicited elevated pro‐inflammatory cytokines, and a minor increase in CD8⁺ T cells, but no change in pro‐tolerogenic Treg cells. Notwithstanding the limitation of no placebo control, the results do not support Intralipid as a candidate intervention to attenuate the Treg cell response in women undergoing ART. Future placebo‐controlled studies are needed to confirm the potential efficacy and clinical significance of Intralipid in attenuating cytokine induction and circulating CD8⁺ T cells.

Immune checkpoints and reproductive immunology: Pioneers in the future therapy of infertility related Disorders?

As co-stimulatory receptors, immune checkpoint molecules are found on the surface of various immune cells and transduce inhibitory signals following ligand binding. The most studied members in this regard include PD-1, TIM-3, and CTLA-4. The physiological part immune checkpoints possess is the prevention of dangerous immune attacks towards self-antigens throughout an immune response, which takes place through the negative regulation of the effector immune cells, through the induction of T-cell exhaustion, for instance. It has recently been suggested that each checkpoint reduces immunoactivation via distinct intracellular mechanisms of signaling. Regulators of immune checkpoints are supposed to participate actively in immune defense mechanisms against infections, preventing autoimmunity, transplantation, and tumor immune evasion. In pregnancy, as an active immunotolerance mechanism which is also natural, the maternal immune system encounters two simultaneous challenges; in addition to accepting the semi-allogeneic fetus, the maternal immune system should also prevent infections. In this regard, the part immune checkpoint molecules possess is particularly interesting. Herein, the current understanding of such part in reproductive immunology is described.

Impaired myeloid-derived suppressor cells are associated with recurrent implantation failure: A case-control study

BACKGROUND

Studies have reported that myeloid-derived suppressor cells (MDSCs) contribute to maintain pregnancy. The aim of this case-control study was to test whether there is a dysregulation of peripheral MDSCs in recurrent implantation failure (RIF).

METHODS

26 RIF patients and 30 controls were recruited. Flow cytometry was applied to characterize polymorphonuclear (PMN)-MDSCs, monocytic-MDSCs (M-MDSCs), effector T cells (Teffs) and regulatory T cells (Tregs) in blood. ELISA was used to define MDSCs correlative cytokines and chemokines in serum from all patients.

RESULTS

Compared with controls, RIF patients showed significant reductions of blood PMN-MDSCs, M-MDSCs, Tregs and NO production by PMN-MDSCs, whereas the expression of ζ chain on CD4+T cell receptor (TCR) and CD8+TCR displayed a remarkable upregulation in RIF patients. Moreover, RIF patients presented a lower concentration of serum chemokine (C-C motif) ligand (CCL) 5 and transforming growth factor (TGF)-β than those from controls. Furthermore, the level of TCR ζ chain on CD4+ and CD8+ Teffs was negatively correlated not only with the percentage of PMN-MDSCs, but also with the amount of NO produced by PMN-MDSCs. The frequency of PMN-MDSCs had positive correlations with the concentration of CCL5 and TGF-β.

CONCLUSIONS

This study indicated that the dysregulation of MDSCs might impair maternal-fetal immune balance thus resulting in RIF.

Understanding the natural selection of human embryos: blastocyst quality modulates the inflammatory response during the peri-implantation period

PROBLEM

Decidualized cells display an active role during embryo implantation sensing blastocyst quality, allowing the implantation of normal developed blastocysts and preventing the invasion of impaired developed ones. Here, we characterized the immune microenvironment generated by decidualized cells in response to soluble factors secreted by blastocysts that shape the receptive milieu.

METHOD OF STUDY

We used an in vitro model of decidualization based on the Human Endometrial Stromal Cells line (HESC) differentiated with medroxiprogesterone and dibutyryl-cAMP, then treated with human blastocysts-conditioned media (BCM) classified according to their quality.

RESULTS

Decidualized cells treated with BCM from impaired developed blastocysts increased IL-1β production. Next, we evaluated the ability of decidualized cells to modulate other mediators associated with menstruation as chemokines. Decidualized cells responded to stimulation with BCM from impaired developed blastocysts increasing CXCL12 expression and CXCL8 secretion. The modulation of these markers was associated with the recruitment and activation of neutrophils, while regulatory T cells recruitment was restrained. These changes were not observed in the presence of BCM from normal developed blastocysts.

CONCLUSION

Soluble factors released by impaired developed blastocysts induce an exacerbated inflammatory response associated with neutrophils recruitment and activation, providing new clues to understand the molecular basis of the embryo-endometrial dialogue.

Effects of treatment with hydroxychloroquine on the modulation of Th17/Treg ratio and pregnancy outcomes in women with recurrent implantation failure: clinical trial

AIM

The imbalance of Th17/Treg cells has been recently suggested as a new risk factors for recurrent implantation failure (RIF). Furthermore Th17/Treg cells are involved in immune regulation in peripheral blood and endometrial tissue of patients with RIF. In this research, we investigated the effects of Hydroxychloroquine (HCQ) on the level and function of Th17 and Treg cells in women with RIF. It may be possible to improve pregnancy outcomes by modulating high cytokine levels.

METHODS

Women with RIF received oral HCQ (n = 60) on day 4 of the menstrual cycle and continued until day 20 of the menstrual cycle and 2 days before embryo transfer and continued until the day of the pregnancy test, for a total of 16 days in another cycle. The serum levels of IL-17 and IL-10, the expression of transcription factors related to Th17 and Treg cells and the immune-reactivity of IL-17, IL-21 as Th17 related cytokines and IL-10, TGF- β as Treg related cytokines in endometrial tissues were evaluated by ELISA, real-time PCR, and fluorescent immunohistochemistry respectively.

Results: Treatment with HCQ down-regulated Th17 related cytokines and function and up-regulated Treg related cytokines and function significantly (p < .001). RORγt, the Th17 transcription factor, expression was down-regulated and FOXP-3, the T-reg transcription factor, expression was up-regulated. The biochemical pregnancy rate was not significantly different in RIF patients before and after treatment.

CONCLUSION

Our results demonstrated that the administration of HCQ in RIF women with immune cell disorders during pregnancy could affect the Th17/Treg ratio and enhance Treg and diminish Th17 responses which may be associated with successful pregnancy outcomes. However, significant difference in pregnancy outcomes was not observed in the present study.

Novel predictive and therapeutic options for better pregnancy outcome in frozen embryo transfer cycles

Since 1978, in the first decades of in vitro fertilization (IVF), the use of ovarian hyperstimulation allowed for the development and transfer of multiple embryos. As IVF technology improved, the number of multiple pregnancies increased, which led to gradual reduction in the number of embryos that were transferred. Embryo freezing (vitrification) was recommended to allow subsequent transfer if the fresh cycle was unsuccessful. However, experimentation has continued to improve pregnancy outcomes. We discuss here the significance of frozen embryo transfer cycle and the impact of uterine and peripheral immunity dominated by NK cells and regulatory T cells and human chorionic gonadotropin on pregnancy outcome in this innovative mode of IVF therapy.

Intrauterine administration of autologous hCG- activated peripheral blood mononuclear cells improves pregnancy outcomes in patients with recurrent implantation failure; A double-blind, randomized control trial study

We aimed to investigate the effect of intrauterine administration of autologous hCG-activated PBMCs in RIF women with low Th-17/Treg cell ratio. 248 women with a history of implantation failure volunteered to receive PBMC-therapy. After immunologic consultation and doing flow cytometry analysis, 100 women with at least three IVF/ET failure who had low Th-17/Treg ratio in comparison with healthy control were enrolled in this study. These 100 patients were randomly divided into two groups as PBMC receiving (n = 50) and controls (n = 50). Then PBMCs were obtained from patients and treated with hCG for 48 h. Afterward, PBMCs were administered into the uterine cavity of the patient in the study group, two days before ET. The concentration of inflammatory cytokines was examined in the supernatant of cultured PBMCs after 2, 24, and 48 h of incubation using the ELISA method. The frequency of Th-17, Treg, and the Th-17/Treg ratio was significantly lower in RIF women than the healthy controls (P < 0.0001). The secretion of inflammatory cytokines was significantly higher after 48 h compared to 2 and 24 h (P < 0.0001). The pregnancy and live birth rate were significantly increased in women undergoing the PBMC-therapy compared to control (PBS-injecting) group (P = 0.032 and P = 0.047, respectively). The miscarriage rate was considerably lower in PBMC-therapy group (P = 0.029). Our findings suggest that intrauterine administration of autologous in vitro hCG-activated PBMCs improves pregnancy outcomes in patients with at least three IVF/ET failures.

Role of Regulatory T Cells in Regulating Fetal-Maternal Immune Tolerance in Healthy Pregnancies and Reproductive Diseases

Regulatory T cells (Tregs) are a specialized subset of T lymphocytes that function as suppressive immune cells and inhibit various elements of immune response in vitro and in vivo. While there are constraints on the number or function of Tregs which can be exploited to evoke an effective anti-tumor response, sufficient expansion of Tregs is essential for successful organ transplantation and for promoting tolerance of self and foreign antigens. The immune-suppressive property of Tregs equips this T lymphocyte subpopulation with a pivotal role in the establishment and maintenance of maternal tolerance to fetal alloantigens, which is necessary for successful pregnancy. Elevation in the level of pregnancy-related hormones including estrogen, progesterone and human chorionic gonadotropin promotes the recruitment and expansion of Tregs, directly implicating these cells in the regulation of fetal-maternal immune tolerance. Current studies have provided evidence that a defect in the number or function of Tregs contributes to the etiology of several reproductive diseases, such as recurrent spontaneous abortion, endometriosis, and pre-eclampsia. In this review, we provide insight into the underlying mechanism through which Tregs contribute to pregnancy-related immune tolerance and demonstrate the association between deficiencies in Tregs and the development of reproductive diseases.

Dynamics of effector and naïve Regulatory T cells throughout pregnancy

Regulatory T (Treg) cells are a specialized subset of T cells possessing immunosuppressive functions indispensable for the maintenance of self-tolerance and pregnancy. However, how functional Treg cells dynamically change and are engaged in feto-maternal tolerance during human pregnancy is still unclear. Recent studies have shown that functionally distinct and immunosuppressive subsets of Treg cells, i.e., effector Treg (eTreg) and naïve Treg (nTreg) cells, can be delineated by combinations of molecular markers and that their proportions differ in normal and disease states. In this study, we examined how the proportion of eTreg and nTreg cells in peripheral blood changes in the 1^st, 2^nd, and 3^rd trimesters of pregnancy and the postpartum period. During the 2^nd trimester the proportion of eTreg cells was reduced while nTreg cells was increased. This pattern was maintained throughout the 3^rd trimester of pregnancy. The kinetics of eTreg reduction highly correlated with migration of eTreg cells into feto-maternal interface while stable nTreg proportion paralleled with their expression of the anti-apoptotic molecule Bcl-2 and production of thymic emigrant naïve Treg cells. These results suggest that further studies on divergence of functional Treg proportions will be helpful for predicting instability of pregnancy.

NK cell subsets in idiopathic recurrent miscarriage and renal transplant patients

The present review article compares NK cell subsets and cytokine patterns determined in the peripheral blood as well as results of functional in-vitro assays using peripheral NK cells of idiopathic recurrent miscarriage (iRM) patients with corresponding results obtained in female healthy controls and female renal transplant recipients with good long-term graft function. Immune mechanisms, inducing transplant rejection in long-term transplant recipients might also be able to induce rejection of semi-allogeneic fetal cells in patients with iRM. Consequently, the immune status of transplant recipients with good stable long-term graft function should be different from the immune status of iRM patients. iRM patients show a strong persistent cytotoxic NK cell response in the periphery. Simultaneously, immunostimulatory Th1 as well as immunosuppressive Th2 type lymphocytes in the blood are strongly activated but plasma levels of immunosuppressive Th2 type cytokines are abnormally low. In-vitro, unstimulated NK cell cultures of iRM patients show a strong spontaneous TGF-ß1 release in the supernatant but lower TGF-ß1 levels after stimulation with tumor cell line K562, suggesting strong consumption of TGF-ß1 by pre-activated NK cells of iRM patients that might contribute to the low systemic Th2 type plasma levels. iRM patients do not show a systemic switch to a Th2 type cytokine pattern and one might hypothesize that low TGF-ß plasma levels indicate low TGF-ß levels in the micromilieu immediately before fetal rejection. Persistent TGF-ß deficiency implies a persistent unfavorable micromilieu for pregnancy resulting in failing tolerance induction due to lack of TGF-ß, a condition that might contribute to iRM.

Human chorionic gonadotropin promotes recruitment of regulatory T cells in endometrium by inducing chemokine CCL2

Human chorionic gonadotropin (hCG) can attract regulatory T cells (Tregs) into the fetal-maternal interface regulating maternal immune tolerance in pregnancy. The objective of this study was to investigate whether hCG recruits the Tregs into endometrium by inducing chemokines. The number of Tregs in the endometrium was analyzed by immunohistochemistry. The expression of CCL2 was analyzed in vivo and in vitro with hCG stimulation. CD4+CD25+ Tregs were isolated from peripheral blood for Tregs migration assay with hCG, CCL2 siRNA and CCR2 antagonist stimulation. Our results showed that the number of endometrial Tregs in RIF patients was significantly decreased (9.4 ± 5.3 vs. 23.1 ± 3.1, P < 0.01), while intrauterine infusion of 2000 IU hCG increased the endometrial Tregs (18.6 ± 9.8 vs. 9.4 ± 5.3, P < 0.05) and CCL2 expression (0.21 ± 0.01 vs. 0.17 ± 0.01, P < 0.01). Horn injecting with 10 IU hCG also increased the endometrial Tregs in pseudopregnant mice (46 ± 16.8 vs. 7 ± 4.3, P < 0.01). Furthermore, the CCL2 protein and mRNA levels were significantly increased in human endometrial stromal cells (hESCs) with the stimulation of hCG. Migration assays showed that hESCs with hCG stimulation promoted Tregs migration (2597 ± 833.2 vs. 1115 ± 670.7, P < 0.05), while the number of migrated Tregs significantly decreased with CCL2 siRNA (1061 ± 105.4 vs. 2598 ± 294.7, P < 0.05) or CCR2 antagonist (356.7 ± 138.8 vs. 2597 ± 833.2, P < 0.05) treatment. In conclusion, intrauterine perfusion of hCG might promote the recruitment of Tregs into endometrium by inducing chemokine CCL2.

Immune checkpoint molecules in pregnancy: Focus on regulatory T cells

Regulatory T (Treg) cells are a specialized subpopulation of T cells that plays critical roles in the maintenance of immune homeostasis. Although efforts have been done, their role in human pregnancy is not fully understood. Numerous studies reported the presence of Treg cells throughout gestation by promoting maternal-fetal tolerance and fetal development. Furthermore, Treg population is heterogeneous as it is expressing different immune checkpoint molecules favoring immune suppressive function. Therefore, better understanding of the heterogeneity and function of Treg cells during pregnancy is critical for an effective immune intervention. Latest evidence has shown that several immune checkpoint molecules are closely associated with pregnancy outcome via multiple inhibitory mechanisms. Majority of these studies demonstrated the modulatory effects of immune checkpoint molecules on effector T-cell immunity, but their effects on Treg activation and function are still an enigma. In this review, we emphasize the potential influence of multiple immune checkpoint molecules, including CTLA-4, PD-1, Tim-3, LAG-3, and TIGIT, either in membrane or soluble form, on the function of decidual and peripheral Treg cells during pregnancy. Additionally, we discuss the promising future of targeting Treg cells via immune checkpoint molecules for pregnancy maintenance and prevention of complicated pregnancies.

VIP Promotes Recruitment of Tregs to the Uterine-Placental Interface During the Peri-Implantation Period to Sustain a Tolerogenic Microenvironment

Uterine receptivity and embryo implantation are two main processes that need a finely regulated balance between pro-inflammatory and tolerogenic mediators to allow a successful pregnancy. The neuroimmune peptide vasoactive intestinal peptide (VIP) is a key regulator, and it is involved in the induction of regulatory T cells (Tregs), which are crucial in both processes. Here, we analyzed the ability of endogenous and exogenous VIP to sustain a tolerogenic microenvironment during the peri-implantation period, particularly focusing on Treg recruitment. Wild-type (WT) and VIP-deficient mice [heterozygous (HT, +/-), knockout (KO, -/-)], and FOXP3-knock-in-GFP mice either pregnant or in estrus were used. During the day of estrus, we found significant histological differences between the uterus of WT mice vs. VIP-deficient mice, with the latter exhibiting undetectable levels of FOXP3 expression, decreased expression of interleukin (IL)-10, and vascular endothelial growth factor (VEGF)c, and increased gene expression of the Th17 proinflammatory transcription factor RORγt. To study the implantation window, we mated WT and VIP (+/-) females with WT males and observed altered FOXP3, VEGFc, IL-10, and transforming growth factor (TGF)β gene expression at the implantation sites at day 5.5 (d5.5), demonstrating a more inflammatory environment in VIP (+/-) vs. VIP (+/+) females. A similar molecular profile was observed at implantation sites of WT × WT mice treated with VIP antagonist at d3.5. We then examined the ability GFP-sorted CD4+ cells from FOXP3-GFP females to migrate toward conditioned media (CM) obtained from d5.5 implantation sites cultured in the absence/presence of VIP or VIP antagonist. VIP treatment increased CD4+FOXP3+ and decreased CD4+ total cell migration towards implantation sites, and VIP antagonist prevented these effects. Finally, we performed adoptive cell transfer of Tregs (sorted from FOXP3-GFP females) in VIP-deficient-mice, and we observed that FOXP3-GFP cells were mainly recruited into the uterus/implantation sites compared to all other tested tissues. In addition, after Treg transfer, we found an increase in IL-10 expression and VEGFc in HT females and allowed embryo implantation in KO females. In conclusion, VIP contributes to a local tolerogenic response necessary for successful pregnancy, preventing the development of a hostile uterine microenvironment for implantation by the selective recruitment of Tregs during the peri-implantation period.

Sirolimus as a new drug to treat RIF patients with elevated Th17/Treg ratio: A double-blind, phase II randomized clinical trial

BACKGROUND

RIF is clinically defined as the failure of good quality embryos to implant into the uterus following at least three cycles of In Vitro Fertilization/Embryo Transfer (IVF/ET). During human pregnancy, a genetically different fetus is allowed to survive within the uterus despite the maternal recognition of fetal alloantigens. Compared with normal pregnant women, early loss of embryo is associated with systemic lower levels of Treg cells in IVF. Moreover, several lines of evidence have indicated that differentiation of naive T cells into Th17 is deleterious for normal pregnancy and may cause implantation failure. Sirolimus as the most common mTOR (mammalian target of Rapamycin) inhibitor is able to effectively prevent allograft rejection. Here we aimed to evaluate Sirolimus effects on Th17/Treg axis and subsequently on pregnancy outcome.

METHODS AND MATERIALS

121 patients with a history of at least 3 implatation failures were selected and enrolled in this clinical trial. Blood was drawn between days 5 and 10 of the cycle prior to the index IVF/ET cycle to assess baseline value of Th17 cells and regulatory T cells ratios using flowcytometry. A Th17/Treg cell ratio equal or >0.74 was considered to be the elevated Th17/Treg cell ratio. In 76 patients with elevated Th17/Treg ratios, 43 individuals were treated with Sirolimus and 33 remained untreated.

RESULTS

Our results demonstrated that Sirolimus treatment led to an increase in Treg cells number and function in treated group and reduced the frequency and function of Th17 cells. Moreover Th17/Treg cell ratio, significantly reduced from 1.18 ± 0.46% to 0.9 ± 0.45% following Sirolimus intervention (P = 0.024). In contrast, no significant difference in Th17 and Treg cell frequencies and Th17/Treg cell ratio was observed in untreated control subjects before and after ET. Finally our data showed a significantly higher clinical pregnancy rate (55.81%) in Sirolimus-treated patients compared with control group (24.24%) (P < 0.0005). We also found a significantly increased live birth rate (48.83%) in RIF women who received Sirolimus compared with control group (21.21%) (P < 0.0001).

CONCLUSION

The findings of the current study revealed the fact that Sirolimus exhibit potent immunosuppressive effects by blocking intracellular immune responses downstream of co-stimulatory signals, also is able to improve reproductive outcome in RIF women with imbalanced Th17/Treg ratio by modulate of Th17 /Treg axis, thus representing a new approach for the potential treatment of patients with embryo implantation failure.

Immune Checkpoint Molecules in Reproductive Immunology

Immune checkpoint molecules, like CTLA-4, TIM-3, PD-1, are negative regulators of immune responses to avoid immune injury. Checkpoint regulators are thought to actively participate in the immune defense of infections, prevention of autoimmunity, transplantation, and tumor immune evasion. Maternal-fetal immunotolerance represents a real immunological challenge for the immune system of the mother: beside acceptance of the semiallogeneic fetus, the maternal immune system has to be prepared for immune defense mostly against infections. In this particular situation, the role of immune checkpoint molecules could be of special interest. In this review, we describe current knowledge on the role of immune checkpoint molecules in reproductive immunology.

New Paradigm in the Role of Regulatory T Cells During Pregnancy

Semi-allogenic fetuses are not rejected by the maternal immune system because feto-maternal tolerance induced by CD4⁺CD25⁺FoxP3⁺ regulatory T (Treg) cells is established during pregnancy. Paternal antigen-specific Treg cells accumulate during pregnancy, and seminal plasma priming plays an important role in expanding paternal antigen-specific Treg cells in mouse models. Although paternal-antigen specific Treg cells have not been identified in humans, recent studies suggest that antigen-specific Treg cells exist and expand at the feto-maternal interface in humans. Studies have also revealed that reduction of decidual functional Treg cells occurs during miscarriage with normal fetal chromosomal content, whereas insufficient clonal expansion of decidual Treg cells is observed in preeclampsia. In this review, we will discuss the recent advances in the investigation of mechanisms underlying Treg cell-dependent maintenance of feto-maternal tolerance.

Intrauterine administration of human chorionic gonadotropin improves the live birth rates of patients with repeated implantation failure in frozen-thawed blastocyst transfer cycles by increasing the percentage of peripheral regulatory T cells

INTRODUCTION

Repeated implantation failure (RIF) frustrates both patients and their clinicians. Our aim was to observe the effects of intrauterine administration of human chorionic gonadotropin (hCG) on pregnancy outcomes of patients who received frozen-thawed embryo transfer (FET).

METHODS

A prospective cohort study was conducted to evaluate the impact of intrauterine administration of hCG on pregnancy outcomes in FET cycles of patients with RIF from January 1st 2016 to December 31st 2016. The treatment group (n = 153, 152 cycles) received an infusion of 500 IU of hCG diluted in normal saline 3 days before embryo transfer. The control group (n = 152, 151 cycles) received embryo transfer with a previous intrauterine injection of normal saline without hCG. Early morning fasting blood samples were obtained from each patient for the measurement of peripheral regulatory T cells (Tregs) on the day of embryo transfer. The outcome parameters including Tregs in each group were compared.

RESULTS

The patients in the hCG-treated group had significantly higher clinical pregnancy rates, implantation rates and live birth rates than the controls (37.5% versus 25.17%, 29.19% versus 19.4%, 26.97% versus 17.22%, respectively). They also had significantly higher percentages of peripheral Tregs than the controls (6.1 ± 0.6% versus 5.4 ± 1.0%). In addition, the clinical pregnancy rate, implantation rate and live birth rate in patients who received blastocyst transfer were significantly higher in the hCG-treated group when compared to the control group (41.38% versus 26.44%, 42.22% versus 26.14%, 33.33% versus 17.24%, respectively). We also showed that the clinical pregnancy rate, implantation rate and live birth rate were significantly higher in hCG-treated group when compared to the control group (49.12% versus 28.07%, 49.15% versus 28.07%, 40.35% versus 17.54%, respectively) of RIF patients with blastocyst transfer under 35 years, while there was on difference in patients above 35 years.

CONCLUSIONS

Intrauterine administration of hCG significantly improves the clinical pregnancy rate, implantation rate and live birth rate in FET cycles of patients with RIF by increasing Tregs. The treatment improves the pregnancy outcomes much more for younger RIF patients transferred blastocysts.

T cell Subsets in Peripheral Blood of Women with Recurrent Implantation Failure

The objective of this study was to determine whether there are any differences in the T cell composition and the expression of specific factors (i.e., IRF4, TBX21, GATA3, and GITR) of T cells between women with Repeated Implantation Failure (RIF) and fertile women. We observed a decrease in circulating Tregs and exhausted CD8 + T cells in RIF patients when compared to the controls whereas exhausted Treg and Th17 cells were more frequent. Using real-time PCR, we determined that the expression of IRF-4 and TBX21 was significantly elevated in the cases. In contrast, mRNAs encoding GATA3 and GITR were reduced. Furthermore, the expression of some miRNAs involved in T cell differentiation and their target gene candidates were examined in T cells from women with RIF and fertile control women. The patients showed significant up-regulation of miR-25, miR-93, and miR-326. miR-155 and miR-146a demonstrated significant down-regulation in RIF patients. The results revealed that the expression pattern of target genes was in line with data for miRNAs expression from purified Treg and Th17 cells. The findings of real-time PCR analysis provided insights into the genetic pathways underlying this aberration in the proportions of T cell subsets. Our data suggest that a combination of higher pro-inflammatory Th17 and exhausted Treg cells, and lower Treg and exhausted CD8 + T cells may co-exist in the peripheral blood of women with RIF. Moreover, the expression level of transcription factors and miRNAs controlling T cell differentiation may differ in women with RIF influencing pregnancy outcomes in these women.

The Link Between Seminal Cytokine Interleukin 18, Female Circulating Regulatory T Cells, and IVF/ICSI Success

Seminal plasma (SP) is thought to be a crucial factor which affects the expansion of regulatory T cells (Tregs) in female reproductive tract during embryo implantation. We propose that seminal transforming growth factor (TGF) β1 is responsible for local accumulation of circulating Tregs, which manifests as changes in Treg frequency in peripheral blood, whereas seminal interleukin (IL) 18 interferes with TGF-β1-dependent cellular reactions. The purpose of the present study is to determine whether the frequency of circulating Tregs is associated with the levels of seminal cytokines and pregnancy establishment in women exposed to partner’s SP during in vitro fertilization (IVF)/intracytoplasmic sperm injection (ICSI) cycle. Twenty-nine women were exposed to SP via timed intercourse before the day of ovum pickup (day-OPU) and also subjected to intravaginal SP application just after OPU. Measurements of seminal TGF-β1 and IL-18 were made by FlowCytomix technology. The percentage of CD4+CD25+CD127low+/ – Tregs among total circulating CD4+ T cells was determined by flow cytometry and the difference between Treg values on the day of embryo transfer and day-OPU was calculated. The percentage of Tregs on the day-OPU, identified as a predictive factor of clinical pregnancy after IVF/ICSI, showed a positive correlation with IL-18 concentration and content of this cytokine per ejaculate ( P < .001 and P < .004, respectively) and negative correlation with the TGF-β1/IL-18 ratio ( P < .014).These findings indicate that the adverse effect of seminal IL-18 excess on implantation may be realized by the prevention of postcoital TGF-β1-related migration of circulating Tregs, which clearly manifests as elevated level of Treg frequency in peripheral blood.

Regulatory T cells in embryo implantation and the immune response to pregnancy

At implantation, the embryo expresses paternally derived alloantigens and evokes inflammation that can threaten reproductive success. To ensure a robust placenta and sustainable pregnancy, an active state of maternal immune tolerance mediated by CD4+ regulatory T cells (Tregs) is essential. Tregs operate to inhibit effector immunity, contain inflammation, and support maternal vascular adaptations, thereby facilitating trophoblast invasion and placental access to the maternal blood supply. Insufficient Treg numbers or inadequate functional competence are implicated in idiopathic infertility and recurrent miscarriage as well as later-onset pregnancy complications stemming from placental insufficiency, including preeclampsia and fetal growth restriction. In this Review, we summarize the mechanisms acting in the conception environment to drive the Treg response and discuss prospects for targeting the T cell compartment to alleviate immune-based reproductive disorders.

Distinct pattern of Th17/Treg cells in pregnant women with a history of unexplained recurrent spontaneous abortion

The aim of the current study was to determine the pattern of immune cells and related functional molecules in peripheral blood and at the maternal-fetal interface in women with unexplained recurrent spontaneous abortion (URSA). In part I, 155 women were included and divided into four groups: non-pregnant controls with no history of URSA (NPCs), pregnant controls with no history of URSA (PCs), non-pregnant women with a history of URSA (NPUs), and pregnant women with a history of URSA (PUs). Venous blood samples were collected and analyzed. In part II, 35 subjects with URSA and 40 subjects in the early stage of normal pregnancy who chose to undergo an abortion were recruited. Samples of the decidua were collected, and the proportion of immune cells and the expression of related molecules were evaluated. Peripheral regulatory T cells (Treg cells) increased in PCs compared to NPCs, but in women with URSA the flux of Treg cells disappeared when pregnancy occurred. Levels of interleukin-10 (IL-10), cytotoxic T lymphocyte-associated antigen 4 (CTLA-4), and IL-17 and the ratio of Th17/Treg cells in peripheral blood remained stable among the four groups. At the maternal-fetal interface, the percentage of Treg cells, the level of CTLA-4 of CD4⁺CD25⁺CD127^lo cells and CD4⁺Foxp3⁺ cells were significantly lower in women with URSA compared to controls, respectively. Levels of transforming growth factor-β1 (TGF-β1) mRNA and protein in the decidua significantly decreased in URSA while levels of IL-6 and tumor necrosis factor-ɑ (TNF-ɑ) and the Th17/Treg ratio significantly increased. In conclusion, peripheral Treg cells did not increase in pregnant women with URSA. The decrease in Treg cells and levels of CTLA-4 and TGF-β1 and as well as the increase in levels of IL-6 and TNF-ɑ, and the Th17/Treg ratio at the maternal-fetal interface might contribute to inappropriate maternal-fetal immune tolerance in URSA.

Abnormal ratio of CD57+ cells to CD56+ cells in women with recurrent implantation failure

PROBLEM

To define a more precise parameter for a better understanding of natural killer (NK) cells and its relation with regulatory T cells (Tregs) in women with recurrent implantation failure (RIF).

METHOD OF STUDY

The percentages of CD56+ cells, CD57+ cells and Foxp3+ cells in the endometrium and blood from 23 normal controls and 32 women with RIF were measured by immunocytochemistry and flow cytometry.

RESULTS

Women with RIF had significantly increased ratio of CD57+ cells to CD56+ cells in both the endometrium (P<.01) and blood (P<.05), and decreased percentage of Foxp3+ cells in the endometrium (P<.05). There was a significant negative correlation between CD57+ cells to CD56+ cells ratio and the percentage of Foxp3+ cells in the blood of RIF patients (P<.05).

CONCLUSION

Our study provides a novel assessment parameter, CD57+ cells to CD56+ cells ratio, to evaluate NK cells and its relation with Tregs in RIF patients.

Increased levels of CCR7(lo)PD-1(hi) CXCR5+ CD4+ T cells, and associated factors Bcl-6, CXCR5, IL-21 and IL-6 contribute to repeated implantation failure

In vitro fertilization-embryo transfer (IVF-ET) can be used by infertile couples to assist with reproduction; however, failure of the embryo to implant into the endometrial lining results in failure of the IVF treatment. The present study investigated the expression of chemokine receptor 7 (CCR7)(lo) programmed death-1(PD-1)(hi) chemokine receptor type 5 (CXCR5)⁺ cluster of differentiation 4 (CD4)⁺ T cells and associated factors in patients with repeated implantation failure (RIF). A total of 30 females with RIF and 30 healthy females were enrolled in the current study. Flow cytometry was used to detect the proportion of CCR7(lo)PD-1(hi) CXCR5⁺ CD4⁺ T cells in the peripheral blood. Cytokine bead arrays were performed to detect the levels of interleukin (IL)-6, −4 and −2 in the serum. ELISAs were used to detect the level of IL-21 in the serum. Quantitative real time polymerase chain reaction analysis and immunohistochemistry were used to investigate the expression of B-cell lymphoma 6 (Bcl-6), chemokine receptor type 5 (CXCR5) and IL-21 in the endometrium. The results revealed that the percentage of CCR7(lo)PD-1(hi) CXCR5⁺ CD4⁺ T cells was increased in the RIF group compared with the control group during the mid luteal phase. The mRNA and protein levels of Bcl-6, IL-21 and CXCR5 in the endometrium and the concentrations of IL-21 and IL-6 in the serum were significantly increased in the RIF group; however, no significant difference was observed between the two groups in regards to the expression of IL-4 and IL-2. Furthermore, a significant positive correlation was identified between the percentage of CCR7(lo)PD-1(hi) CXCR5⁺ CD4⁺ T cells and IL-21 and IL-6 levels. The expression of IL-21 also had a positive correlation with Bcl-6 and CXCR5 expression in the RIF group. These results suggest that increased levels of CCR7(lo)PD-1(hi) CXCR5⁺ CD4⁺ T cells and associated factors contribute to RIF and could therefore be a potential therapeutic target.

Aberrant expressions of endometrial Id3 and CTLA-4 are associated with unexplained repeated implantation failure and recurrent miscarriage

Inhibitor of DNA-binding protein 3 (Id3) is required for tumor angiogenesis and regulatory T-cell generation. However, the involvement of Id3 in unexplained repeated implantation failure (RIF) and recurrent miscarriage (RM) remains poorly understood. Immunohistochemistry was used to identify Id3, CD34, CTLA-4, and FOXP3 in the endometrium taken from the women with RIF (n=16), RM (n=16) and matched controls (n=8). The images were acquired and analyzed by the Vectra^® automated quantitative pathology imaging system. Percentage of Id3⁺ cells was significantly higher in the endometrium of women with RIF and RM compared with controls. The numbers of Id3⁺ and CD34⁺ vessels in the endometrium were positively correlated in control but not in RIF or RM. Percentages of CTLA-4⁺ cells, but not FOXP3⁺ cells, were significantly increased in the endometrium of RIF and RM women than those in controls. We found aberrant expressions of endometrial Id3 and CTLA-4 in peri-implantation endometrium of women with RIF and RM, suggesting the negative roles of these angiogenesis and immune tolerance markers involving in regulating endometrium receptivity.

Human chorionic gonadotropin potentially affects pregnancy outcome in women with recurrent implantation failure by regulating the homing preference of regulatory T cells

PROBLEM

Human chorionic gonadotropin (hCG) and regulatory T cells (Tregs) have been suggested to play important roles during the initial stage of pregnancy. However, the clinical relevance and mechanism of the effects of hCG on Treg functions in women with recurrent implantation failure (RIF) remain to be elucidated.

METHOD OF STUDY

Thirty-four RIF and twenty-three control women were included in the study. Endometrial and peripheral Tregs were analyzed by immunohistochemistry and flow cytometry, respectively. Tregs were generated from naïve CD4⁺ T cells by stimulation with anti-CD3/CD28 in the presence or absence of hCG, and the subsets were analyzed by flow cytometry, Western blotting, and qPCR.

RESULTS

The percentages of endometrial FOXP3⁺ Tregs and peripheral CCR4⁺ FOXP3⁺ Tregs were significantly lower in the women with RIF than in the healthy controls. In addition, the percentages of CCR4⁺ FOXP3⁺ Tregs and TGF-β-expressing FOXP3⁺ Tregs were increased following the stimulation of naïve CD4⁺ T cells with anti-CD3/CD28, and these increases were concomitant with AKT and ERK dephosphorylation.

CONCLUSIONS

The results of this study provide novel evidence supporting a role of hCG in regulating the differentiation of peripheral FOXP3⁺ Tregs. The alterations of circulating Tregs may positively affect the pregnancy outcomes of patients with a history of RIF.

Curcumin inhibits placental inflammation to ameliorate LPS-induced adverse pregnancy outcomes in mice via upregulation of phosphorylated Akt

INTRODUCTION

Excessive inflammation results in adverse pregnancy outcomes, including embryonic resorption, fetal growth restriction, and preeclampsia. This study investigated whether curcumin, a highly safe anti-inflammation drug, had protective effect on lipopolysaccharide (LPS)-treated pregnant mice.

METHOD

A mouse model of LPS-induced adverse pregnancy outcomes was generated by daily administering LPS from GD 13.5 to GD 16.5. Curcumin was given from GD 0.5. The effects of curcumin on maternal hypertension, proteinuria, pregnancy outcomes, as well as proinflammatory factors, chemokines, Akt, JNK, and P38 levels in placenta were examined.

RESULTS

Systolic blood pressure (156.6 ± 5.056 versus 125.5 ± 3.617 mmHg; P < 0.05) and proteinuria (22.36 ± 2.22 versus 12.70 ± 1.04 mg/L; P < 0.05) were decreased in the LPS+curcumin-treated group, as compared with the LPS-treated group. Curcumin also increased the number of live pups, fetal weight, and placental weight, while it decreased fetal resorption rate. Moreover, increased placental TNF-α, IL-1β, and IL-6 expressions in LPS-treated group were significantly suppressed after curcumin administration. Furthermore, decreased p-Akt level in placenta induced by LPS was improved by curcumin. Of note, the expression of p-Akt increased by curcumin was accompanied by the decreased chemokines MCP-1 and MIP-1 levels and fewer CD68-positive macrophages in the placenta.

CONCLUSION

Curcumin inhibited the expression of proinflammatory factors and macrophage infiltration in placenta and ameliorated LPS-induced adverse pregnancy outcomes in mice by inhibiting inflammation via upregulation of phosphorylated Akt.

Differentiation of ICOS+ and ICOS- recent thymic emigrant regulatory T cells (RTE T regs) during normal pregnancy, pre-eclampsia and HELLP syndrome

Two different subsets of naturally occurring regulatory T cells (nTregs), defined by their expression of the inducible co-stimulatory (ICOS) molecule, are produced by the human thymus. To examine the differentiation of ICOS(+) and ICOS(-) CD45RA(+) CD31(+) recent thymic emigrant (RTE) T regs during normal pregnancy and in the presence of pre-eclampsia or haemolysis elevated liver enzymes low platelet (HELLP)-syndrome, we used six-colour flow cytometric analysis to determine the changes in the composition of the ICOS(+) and ICOS(-) T reg pools with CD45RA(+) CD31(+) RTE T regs, CD45RA(+) CD31(-) mature naive (MN) T regs, CD45RA(-) CD31(+) and CD45RA(-) CD31(-) memory Tregs. With the beginning of pregnancy until term, we observed a strong differentiation of both ICOS(+) and ICOS(-) CD45RA(+) CD31(+) RTE, but not CD45RA(+) CD31(-) MN T regs, into CD45RA(-) CD31(-) memory T regs. At the end of pregnancy, the onset of spontaneous term labour was associated with a significant breakdown of ICOS(+) CD45RA(-) CD31(-) memory T regs. However, in the presence of pre-eclampsia, there was a significantly increased differentiation of ICOS(+) and ICOS(-) CD45RA(+) CD31(+) RTE T regs into CD45RA(-) CD31(+) memory T regs, wherein the lacking differentiation into CD45RA(-) CD31(-) memory T regs was partially replaced by the increased differentiation of ICOS(+) and ICOS(-) CD45RA(+) CD31(-) MN Tregs into CD45RA(-) CD31(-) memory T regs. In patients with HELLP syndrome, this alternatively increased differentiation of CD45RA(-) CD31(-) MN T regs seemed to be exaggerated, and presumably restored the suppressive activity of magnetically isolated ICOS(+) and ICOS(-) T regs, which were shown to be significantly less suppressive in pre-eclampsia patients, but not in HELLP syndrome patients. Hence, our findings propose that the regular differentiation of both ICOS(+) and ICOS(-) CD45RA(+) CD31(+) RTE T regs ensures a healthy pregnancy course, while their disturbed differentiation is associated with the occurrence of pre-eclampsia and HELLP syndrome.

Role of Paternal Antigen-Specific Treg Cells in Successful Implantation

Maternal lymphocytes recognize fetal antigens, so tolerance is necessary to prevent rejection. Seminal plasma is important for induction of paternal antigen-specific Treg cells in the uterine draining lymph nodes and the pregnant uterus. Elimination of Treg cells during implantation or early pregnancy induces implantation failure or fetal resorption in mice. Immunosuppressive therapy with an anti-TNF antibody or the immunosuppressive agent tacrolimus improves the pregnancy rate in women with repeated implantation failure and recurrent pregnancy loss of unknown etiology, suggesting that Treg cells play an essential role in successful implantation and pregnancy in humans.

The role of recent thymic emigrant-regulatory T-cell (RTE-Treg) differentiation during pregnancy

During pregnancy, regulatory T cells (Tregs) have a key role in maternal immune tolerance to the semi-allogeneic fetus. Our previous results showed that the naive CD45RA(+)-Treg pool is functionally improved in pregnant women compared with non-pregnant women. Therefore, we examined the thymic output and differentiation of CD45RA(+)CD31(+) recent thymic emigrant (RTE)-Tregs during normal pregnancy and in the presence of preeclampsia. With the onset of pregnancy, the composition of the total CD4(+)CD127(low+/-)FoxP3(+)-Treg pool changed in the way that its percentage of RTE- and CD45RA(-)CD31(+)-memory Tregs decreased strongly, whereas that of the CD45RA(+)CD31(-)-mature naive (MN)-Tregs did not change and that of the CD45RA(-)CD31(-)-memory Tregs increased complementary. Thereby, the ratio of RTE-/MN-Tregs decreased from 1.0 to 0.7 leading to a significant increase in the suppressive activity of the naive CD45RA(+)-Treg pool. This effect was confirmed by re-assembling separated RTE- and MN-Tregs from non-pregnant women in the ratio of pregnant women. The suppressive activity of both separated naive Treg subsets was equally high in non-pregnant and pregnant women, but considerably reduced in preeclampsia patients, who showed significantly increased percentages of CD45RA(-)CD31(+)-memory Tregs, but decreased percentages of RTE- and MN-Tregs. Our results suggest a reduced thymic output of RTE-Tregs during pregnancy, which causes a decrease in the ratio of RTE-/MN-Tregs and thus an increase in the differentiation of RTE-Tregs towards CD45RA(-)CD31(-)-memory Tregs. Presumably, this differentiation of RTE-Tregs, which was impaired in preeclampsia patients, ensures the improved suppressive activity of the CD45RA(+)-naive Treg pool and thus retains the maintenance of pregnancy.

Chemokine Ligand 20: A Signal for Leukocyte Recruitment During Human Ovulation?

Ovulation is one of the cornerstones of female fertility. Disruption of the ovulatory process results in infertility, which affects approximately 10% of couples. Using a unique model in which the dominant follicle is collected across the periovulatory period in women, we have identified a leukocyte chemoattractant, chemokine ligand 20 (CCL20), in the human ovary. CCL20 mRNA is massively induced after an in vivo human chorionic gonadotropin (hCG) stimulus in granulosa (>10 000-fold) and theca (>4000-fold) cells collected during the early ovulatory (12-18 h) and late ovulatory (18-34 h) periods after hCG administration. Because the LH surge sets in motion an inflammatory reaction characterized by an influx of leukocytes and CCL20 is known to recruit leukocytes in other systems, the composition of ovarian leukocytes (CD45+) containing the CCL20 receptor CCR6 was determined immediately prior to ovulation. CD45+/CCR6+ cells were primarily natural killer cells (41%) along with B cells (12%), T cells (11%), neutrophils (10%), and monocytes (9%). Importantly, exogenous CCL20 stimulated ovarian leukocyte migration 59% within 90 minutes. Due to the difficulties in obtaining human follicles, an in vitro model was developed using granulosa-lutein cells to explore CCL20 regulation. CCL20 expression increased 40-fold within 6 hours after hCG, was regulated partially by the epithelial growth factor pathway, and was positively correlated with progesterone production. These results demonstrate that hCG dramatically increases CCL20 expression in the human ovary, that ovarian leukocytes contain the CCL20 receptor, and that CCL20 stimulates leukocyte migration. Our findings raise the prospect that CCL20 may aid in the final ovulatory events and contribute to fertility in women.