Uterine natural killer cells, implantation failure and recurrent miscarriage

Immune-metabolic adaptations in pregnancy: A potential stepping-stone to sepsis

Physiological shifts during pregnancy predispose women to a higher risk of developing sepsis resulting from a maladapted host-response to infection. Insightful studies have delineated subtle point-changes to the immune system during pregnancy. Here, we present an overlay of these point-changes, asking what changes and when, at a physiological, cellular, and molecular systems-level in the context of sepsis. We identify distinct immune phases in pregnancy delineated by placental hormone-driven changes in homeostasis setpoints of the immune and metabolic systems that subtly mirrors changes observed in sepsis. We propose that pregnancy immune-metabolic setpoint changes impact feedback thresholds that increase risk for a maladapted host-response to infection and thus act as a stepping-stone to sepsis. Defining maternal immune-metabolic setpoint changes is not only vital for tailoring the right diagnostic tools for early management of maternal sepsis but will facilitate an unravelling of the pathophysiological pathways that predispose an individual to sepsis.

microRNA-based signatures obtained from endometrial fluid identify implantative endometrium

STUDY QUESTION

Is it possible to use free and extracellular vesicle-associated microRNAs (miRNAs) from human endometrial fluid (EF) samples as non-invasive biomarkers for implantative endometrium?

SUMMARY ANSWER

The free and extracellular vesicle-associated miRNAs can be used to detect implantative endometrium in a non-invasive manner.

WHAT IS KNOWN ALREADY

miRNAs and extracellular vesicles (EVs) from EF have been described as mediators of the embryo–endometrium crosstalk. Therefore, the analysis of miRNA from this fluid could become a non-invasive technique for recognizing implantative endometrium. This analysis could potentially help improve the implantation rates in ART.

STUDY DESIGN, SIZE, DURATION

In this prospective study, we first optimized different protocols for EVs and miRNA analyses using the EF of a setup cohort (n = 72). Then, we examined differentially expressed miRNAs in the EF of women with successful embryo implantation (discovery cohort n = 15/validation cohort n = 30) in comparison with those for whom the implantation had failed (discovery cohort n = 15/validation cohort n = 30). Successful embryo implantation was considered when pregnancy was confirmed by vaginal ultrasound showing a gestational sac 4 weeks after embryo transfer (ET).

PARTICIPANTS/MATERIALS, SETTING, METHODS

The EF of the setup cohort was obtained before starting fertility treatment during the natural cycle, 16–21 days after the beginning of menstruation. For the discovery and validation cohorts, the EF was collected from women undergoing frozen ET on Day 5, and the samples were collected immediately before ET. In this study, we compared five different methods; two of them based on direct extraction of RNA and the other three with an EV enrichment step before the RNA extraction. Small RNA sequencing was performed to determine the most efficient method and find a predictive model differentiating between implantative and non-implantative endometrium. The models were confirmed using quantitative PCR in two sets of samples (discovery and validation cohorts) with different implantation outcomes.

MAIN RESULTS AND THE ROLE OF CHANCE

The protocols using EV enrichment detected more miRNAs than the methods based on direct RNA extraction. The two most efficient protocols (using polymer-based precipitation (PBP): PBP-M and PBP-N) were used to obtain two predictive models (based on three miRNAs) allowing us to distinguish between an implantative and non-implantative endometrium. The first Model 1 (PBP-M) (discovery: AUC = 0.93; P-value = 0.003; validation: AUC = 0.69; P-value = 0.019) used hsa-miR-200b-3p, hsa-miR-24-3p and hsa-miR-148b-3p. Model 2 (PBP-N) (discovery: AUC = 0.92; P-value = 0.0002; validation: AUC = 0.78; P-value = 0.0002) used hsa-miR-200b-3p, hsa-miR-24-3p and hsa-miR-99b-5p. Functional analysis of these miRNAs showed strong association with key implantation processes such as in utero embryonic development or transforming growth factor-beta signaling.

LARGE SCALE DATA

The FASTQ data are available in the GEO database (access number GSE178917).

LIMITATIONS, REASONS FOR CAUTION

One important factor to consider is the inherent variability among the women involved in the trial and among the transferred embryos. The embryos were pre-selected based on morphology, but neither genetic nor molecular studies were conducted, which would have improved the accuracy of our tests. In addition, a limitation in miRNA library construction is the low amount of input RNA.

WIDER IMPLICATIONS OF THE FINDINGS

We describe new non-invasive protocols to analyze miRNAs from small volumes of EF. These protocols could be implemented in clinical practice to assess the status of the endometrium before attempting ET. Such evaluation could help to avoid the loss of embryos transferred to a non-implantative endometrium.

STUDY FUNDING/COMPETING INTEREST(S)

J.I.-P. was supported by a predoctoral grant from the Basque Government (PRE_2017_0204). This study was partially funded by the Grant for Fertility Innovation (GFI, 2011) from Merck (Darmstadt, Germany). It was also supported by the Spanish Ministry of Economy and Competitiveness MINECO within the National Plan RTI2018-094969-B-I00, the European Union's Horizon 2020 research and innovation program (860303), the Severo Ochoa Centre of Excellence Innovative Research Grant (SEV-2016-0644) and the Instituto de Salud Carlos III (PI20/01131). The funding entities did not play any role in the study design, collection, analysis and interpretation of data, writing of the report or the decision to submit the article for publication. The authors declare no competing interests.

Exposure to corticosteroids in the first trimester is associated with an increased risk of urogenital congenital anomalies

STUDY QUESTION

Does maternal exposure to first trimester corticosteroids in IVF/ICSI treatment result in an increased risk of congenital anomalies?

SUMMARY ANSWER

Children born with the aid of IVF/ICSI whose mothers were treated with adjuvant corticosteroids during the first trimester had an increased risk of cryptorchidism, hypospadias and talipes.

WHAT IS KNOWN ALREADY

Maternal exposure to corticosteroids may increase the risk of congenital anomalies such as cleft palate and neural tube defects. However, the existing studies have conflicting outcomes, are underpowered, and do not study a population undergoing IVF/ICSI, a group known to be at increased risk of abnormalities.

STUDY DESIGN, SIZE, DURATION

This retrospective cohort analysis covering Monash IVF fertility clinics in Melbourne, Australia assessed the outcomes of 12 426 live births from both fresh and frozen embryo transfers between 2010 and 2016.

PARTICIPANTS/MATERIALS, SETTING, METHODS

There were 618 live births included in our study group of mothers exposed to corticosteroids (oral prednisolone or dexamethasone) during their IVF/ICSI treatment, with the remainder of births not exposed to steroids (control, n = 11 808). The primary outcome measured was the presence of congenital anomalies and secondary outcomes were birth weight and gestation length. Multivariate binary logistic regression was used to assess the independent effects of corticosteroid exposure and the freezing of embryos, with adjustment for maternal age at oocyte retrieval, smoking status, number of cycles taken, BMI, etiology of the infertility and the use of ICSI. Results are presented as incidence rate ratios (IRRs) with 95% CIs.

MAIN RESULTS AND THE ROLE OF CHANCE

Amongst 12 426 live births, and 597 birth defects, multivariate logistic regression demonstrated there was an increased incidence in talipes equinovarus (1.33% vs 0.32%, adjusted IRR = 4.30, 95% CI = 1.93, 9.58; P < 0.001), hypospadias (0.66% vs 0.18%, adjusted IRR = 5.90, 95% CI = 2.09, 16.69; P = 0.001) and cryptorchidism (0.83% vs 0.19%, adjusted IRR = 5.53, 95% CI = 1.91, 15.42; P = 0.001) in the offspring of mothers exposed to corticosteroids compared to those who were unexposed. The incidence of neither neural tube defects nor cleft palate were significantly increased in babies exposed to corticosteroids. The sex ratio of infants exposed to corticosteroids during a fresh embryo transfer cycle significantly favored males but reverted to the normal sex ratio in infants conceived in frozen embryo transfer cycles.

LIMITATIONS, REASONS FOR CAUTION

This was a retrospective observational cohort study using administrative datasets with the potential for measurement error and unobserved confounding. Missing outcome data were obtained from patients using self-report leading to possible ascertainment bias. Given the rare incidence of some of the anomalies assessed, the study was underpowered to identify differences in abnormality rates for some specific anomalies.

WIDER IMPLICATIONS OF THE FINDINGS

The findings of this study, the largest of its kind, suggest that caution should be heeded when prescribing corticosteroids to women undergoing IVF/ICSI, given that this study has now identified three previously unassociated serious neonatal complications (talipes, hypospadias and cryptorchidism), plus a potential alteration in sex ratio. Physicians should be careful in using corticosteroids in the critical first trimester and should counsel patients regarding the potential risks of this treatment.

STUDY FUNDING/COMPETING INTEREST(S)

There was no funding sought or obtained for this study. K.T., V.T., B.V. and D.Z.-F. are employees or contractors to Monash IVF and hold a minority stock position in Monash IVF. R.J.W. reports no conflict of interest.

TRIAL REGISTRATION NUMBER

N/A.

Intravenous immunoglobulins improve live birth rate among women with underlying immune conditions and recurrent pregnancy loss: a systematic review and meta-analysis

Intravenous immunoglobulin (IVIG) is increasingly used as a treatment for recurrent pregnancy loss (RPL) despite lack of clear evidence on efficacy. Recent data suggest IVIG might be more effective in a subgroup of women with an aberrant immunological profile. Therefore, a systematic review and meta-analysis of studies on the effectiveness of IVIG treatment on pregnancy outcome among women with RPL and underlying immunological conditions (e.g., elevated NK cell percentage, elevated Th1/Th2 ratio, diagnosis with autoimmune disorders) was conducted. Eight non-randomized controlled trials, including 478 women (intervention: 284; control: 194), met eligibility criteria. Meta-analysis showed that treatment with IVIG was associated with a two-fold increase in live birth rate (RR 1.98, 95% CI 1.44–2.73, P < 0.0001). The effect of IVIG was particularly marked in the subgroup of studies including patients based on presence of elevated (> 12%) NK-cell percentage (RR 2.32, 95% CI 1.77–3.02, P < 0.0001) and when starting intervention prior to or during cycle of conception (RR 4.47, 95% CI 1.53–13.05, P = 0.006). In conclusion, treatment with IVIG may improve live birth rate in women with RPL and underlying immune conditions. However, these results should be interpreted with caution as studies are limited by low number of participants and the non-randomized design, which represent seriously biases. Future randomized controlled trials in women with RPL and underlying immune conditions are needed before using IVIG in a clinical setting.

Tumor necrosis factor inhibitors as therapeutic agents for recurrent spontaneous abortion (Review)

Recurrent spontaneous abortion (RSA) is a troublesome pregnancy disorder that manifests as sequential early pregnancy losses; its causes are diverse and complex. Among the known possible causes of RSA, the development of an immune disorder in response to the embryo appears to be the most pronounced. The imbalance between immune rejection and immune tolerance contributes to pregnancy loss in females with RSA, wherein the abnormal ratio of T helper (Th)1 cell‑related cytokines [predominantly tumor necrosis factor (TNF)‑α] and Th2 cell‑related cytokines is a strong risk factor for RSA. TNF‑α is a pro‑inflammatory cytokine and TNF inhibitors have been effective in the treatment of various autoimmune diseases, such as ankylosing spondylitis, and inflammatory diseases, such as ulcerative colitis. Based on their immunomodulatory properties, TNF inhibitors have been used in the treatment of RSA to reduce the immune rejection rate and improvement in pregnancy outcomes has been observed in females suffering from RSA who were treated with TNF inhibitors. The aim of the present review was to interpret the involvement of TNF‑α in the immunological disorder underlying RSA and summarize the clinical outcomes of TNF inhibitor treatment in patients with RSA.

The Role of Uterine Natural Killer Cells on Recurrent Miscarriage and Recurrent Implantation Failure: From Pathophysiology to Treatment

Uterine natural killer (uNK) cells constitute a unique uterine leucocyte subpopulation facilitating implantation and maintaining pregnancy. Herein, we critically analyze current evidence regarding the role of uNK cells in the events entailed in recurrent implantation failure (RIF) and recurrent miscarriages (RM). Data suggest an association between RIF and RM with abnormally elevated uNK cells’ numbers, as well as with a defective biological activity leading to cytotoxicity. However, other studies do not concur on these associations. Robust data suggesting a definitive causative relationship between uNK cells and RIF and RM is missing. Considering the possibility of uNK cells involvement on RIF and RM pathophysiology, possible treatments including glucocorticoids, intralipids, and intravenous immunoglobulin administration have been proposed towards addressing uNK related RIF and RM. When considering clinical routine practice, this study indicated that solid evidence is required to report on efficiency and safety of these treatments as there are recommendations that clearly advise against their employment. In conclusion, defining a causative relationship between uNK and RIF–RM pathologies certainly merits investigation. Future studies should serve as a prerequisite prior to proposing the use of uNK as a biomarker or prior to targeting uNK cells for therapeutic purposes addressing RIF and RM.

Down-regulation of HLA-DRs and HLA-DPs reflects the deficiency of antigen-presenting cells in endometrium from infertile women with and without ovarian endometriosis

This study aimed to explore common molecular changes in the infertile endometrium from women with and without endometriosis (EM). By analyzing the dataset GSE120103 from Gene Expression Omnibus, a total of 3252 shared differentially expressed genes were identified between ovarian EM in infertile vs. fertile endometrium and EM-free infertile vs. fertile endometrium. In addition, the gene annotation and pathway analysis of the shared differentially expressed genes with the same expression trend indicated that the pathway 'MHC class II antigen presentation' and five candidate genes: HLA-DRA, HLA-DRB1, HLA-DRB3, HLA-DPA1, HLA-DPB1 were both down-regulated in infertile endometrium with or without EM. Logistic regression showed that HLA-DRA might be an independent predictor of the infertile status of the endometrium. Single sample gene set enrichment analysis (ssGSEA) showed that some classic antigen-presenting cells: macrophages type 1, macrophages type 2, and mature dendritic cells were significantly down-regulated in infertile endometrium with or without EM, whose enrichment correlated positively with the expression of candidate HLA molecules. Hence, the down-regulation of HLA-DRs and HLA-DPs reflecting the deficiency of antigen-presenting cells in endometrium might serve as a common biomarker for diagnosing endometrium-associated infertility in women with and without endometriosis.

Intralipid infusion at time of embryo transfer in women with history of recurrent implantation failure: A systematic review and meta-analysis

AIM

Recurrent implantation failure (RIF) affects 10% of couples undergoing assisted conception, often due to poor endometrial receptivity. We conducted a systematic review and meta-analysis to evaluate the effectiveness of Intra-venous intralipid (IVI) in improving pregnancy rates in women with history of RIF using.

METHODS

We searched MEDLINE, EMBASE, and CENTRAL for any randomized trials evaluating the use of IVI at the time of embryo transfer in women undergoing assisted conception until September 2020. We extracted data in duplicate and assessed risk of bias using the Cochrane Risk of Bias tools. We meta-analyzed data using a random effect model.

RESULTS

We included five randomized trials reporting on 843 women with an overall moderate risk of bias. All trials used 20% IVI solution at the time of embryo transfer compared to normal saline infusion or no intervention (routine care). The IVI group had a higher chance of clinical pregnancy (172 vs 119, risk ratio [RR] 1.55, 95% confidence interval [CI] 1.16-2.07, I² 44.2%) and live birth (132 vs 73, RR 1.83, 95% CI 1.42-2.35, I² 0%) post treatment compared to no intervention. Our findings are limited by the small sample size and the variations in treatment protocols and population characteristics.

CONCLUSION

There is limited evidence to support the use of IVI at the time of embryo transfer in women with the history of RIF. More research is needed before adopting it in clinical practice.

Tryptophan and kynurenine stimulate human decidualization via activating Aryl hydrocarbon receptor: Short title: Kynurenine action on human decidualization

Decidualization is essential for successful pregnancy in rodents and primates. Although L-Tryptophan and its metabolites are essential for mammalian pregnancy, the underlying mechanism is poorly defined. We explored effects of tryptophan and kynurenine on human in vitro decidualization in human endometrial stromal cell line and primary endometrial stromal cells. Tryptophan significantly stimulates the expression of prolactin and insulin growth factor binding protein 1, reliable markers for human decidualization. When stromal cells are treated with tryptophan, tryptophan hydroxylase-1 remains unchanged, but indoleamine 2,3-dioxygenase 1 is significantly increased, suggesting tryptophan is mainly metabolized through kynurenine pathway. Kynurenine significantly stimulates insulin growth factor binding protein 1 expression. Aryl hydrocarbon receptor and its target genes (P450 1A1 and P450 1B1) are significantly increased by tryptophan and kynurenine. The induction of tryptophan and kynurenine on insulin growth factor binding protein 1 is abrogated by CH223191, an aryl hydrocarbon receptor inhibitor. Cytochrome P450 1A1 and P450 1B1 catalyze the oxidative metabolism of estradiol to catechol estrogens (2-hydroxy estradiol and 4-hydroxy estradiol), respectively. Insulin growth factor binding protein 1 is up-regulated by 2-hydroxy estradiol and 4-hydroxy estradiol. Interferon-γ significantly induces the expression of indoleamine 2,3-dioxygenase 1, aryl hydrocarbon receptor and insulin growth factor binding protein 1. All the data are also verified in primary human stromal cells. Our data indicate that Interferon-γ-induced kynurenine pathway promotes human decidualization via aryl hydrocarbon receptor signaling.

Increase in FoxP3, CD56 immune cells and decrease in glands PGRMC1 expression in the endometrium are associated with recurrent miscarriages

OBJECTIVE

Recurrent miscarriage (RM) is a multifactorial condition that involves frequent uterine anatomical abnormalities, parental karyotype abnormalities, and clotting disorders. We investigate the potential roles of endometrium FoxP3⁺ Tregs and CD56+ cells (uNK cells) and endometrial expression of PGRMC1 in the development of recurrent miscarriage.

STUDY DESIGN

This prospective study included 102 out of 286 cases of SA patients. The cases were divided into groups with RM (+RM) and without RM (-RM). Immunohistochemistry staining was made using primary antibodies to FoxP3, CD56, and PGRMC1 in both groups. Morphometry analyses were carried out in 10 non-overlapping high power fields. Mann-Whitney U test, Fisher two-tail test, correlation analysis and relative risk (RR) were evaluated. A p < 0.05 was considered statistically significant.

RESULTS

An increased presence of CD56-positive (p < 0.001) and FoxP3⁺ Treg (p = 0.0005) cells was found in the endometrium, with a reduction in PGRMC1 expression compared with -RM group (p = 0.004). A positive correlation was shown between the number of CD56-positive cells and FoxP3⁺ cells (r = 0.55), and an inverse correlation with PGRMC1 (r =  -0.35) in the + RM group. A similar observation was found in the -RM group, with a positive correlation of uNK cell number with the number of pregnancies (p < 0.001; r = 0.34). Endometrial infiltration of CD56-positive (p < 0.0001) and FoxP3⁺ (p < 0.0001) cells revealed an increased relative risk of RM. This increased risk was also revealed in SA with a loss of PGRMC1 expression (p < 0.0001).

CONCLUSION

Our prospective study suggests, for the first time, that increased endometrial infiltration of uNK, FoxP3⁺ Treg cells and a decreased PGRMC1 expression may play potential roles in the development of RM.

Human prostasomes an extracellular vesicle - Biomarkers for male infertility and prostrate cancer: The journey from identification to current knowledge

Extracellular vesicles (EVs) are gaining attention among the cell biologists and researchers over the last two decades. Prostasomes are considered to be (Evs) secreted by prostate epithelial cells into the semen during emission or ejaculation. Prostasomes contain various proteins required for immune regulation namely, amino and dipeptidyl peptidase; endopeptidase (neutral); decay accelerating factor; angiotensin-converting enzyme. Sperm cells need a few prerequisites in order to fertilize the egg. The role of prostasomes in enhancing the male fertility was reviewed extensively throughout the manuscript. Also, prostasomes have an immunosuppressive, immunomodulatory, antibacterial role in the female reproductive tract, and in some cases they can be used as immunocontraceptive agent to regulate the fertility status. This review will give insights to many active researchers in the field of prostasomal research and male infertility/fertility research. This review will open many unanswered mechanisms of prostasomes with respect to structure-function analysis, fatty acids patterns in diagnosis as well as prognosis of male infertility/fertility. More scientific reports are in need to support the mechanism of prostasomes and its role in immunomodulation. The development of prostasomes as a biomarker for the prostate cancer is still miserable with a lot of controversial results by various researchers.

The involvement of the progesterone receptor in PIBF and Gal-1 expression in the mouse endometrium

PROBLEM

The progesterone-regulated genes, PIBF and Gal-1, are key players in the feto-maternal immunological interaction. This study aims to investigate the expression of PIBF and Gal-1 in WT and progesterone receptor KO models as well as subsequent effects of PIBF on decidualization of stromal cells.

METHOD OF THE STUDY

PRAKO, PRBKO and PRKO BALB/c mice were used for assessing the role of PR isoforms in PIBF induction. PIBF- and Gal-1 mRNA expression in the uterus was tested by real-time PCR. The effect of PIBF on decidualization of endometrial stromal cells was verified by anti-desmin immunofluorescence. Immunohistochemistry was used for testing PIBF expression in the uterus. Gal-1, ERα and PR positive decidual NK cells were detected by immunofluorescence.

RESULTS

PIBF mRNA was significantly increased in progesterone-treated WT mice, but not in PRKO and PRAKO mice. PIBF protein expression was reduced in the endometria of PRKO and PRAKO, but not in PRBKO mice. During a 6-day culture, PIBF induced decidual transformation of endometrial stromal cells. PIBF expression in the mouse uterus was highest during the implantation window, while Gal-1 mRNA expression continuously increased between day 2.5 and day 11.5 of gestation. Decidual NK cells express Gal-1 and ERα, but not PR at day 7.5 murine pregnancy.

CONCLUSION

PIBF produced via engagement of PRA, is highly expressed in the endometrium during the implantation window, and plays a role in decidualization. The concerted action of PIBF and Gal-1 might contribute to the low cytotoxic activity of decidual NK cells.

Endometrial lymphocyte concentrations in adverse reproductive outcome populations

PURPOSE

The uterine immunophenotype is relatively poorly understood, with most studies reporting proportions/percentages. A novel technique to calculate local endometrial lymphocyte concentrations is described, and used to compare results between aetiological subgroups such as repeated implantation failure (RIF) and recurrent pregnancy loss (RPL) with male-factor controls.

METHODS

455 patients had an endometrial biopsy performed. Background history on initial presentation was used to subdivide the population into RIF (n = 149), RPL (n = 121), primary (n = 76) and secondary infertility (n = 80). A control group was identified comprising male factor infertility aetiology with all female investigations normal (n = 29). Endometrial Tissue was assessed using a comprehensive multi-parameter panel. Lymphocyte subpopulations were calculated using flowcount flurospheres and a mathematical correction applied to determine concentrations per milligram of tissue, based on original biopsy weight and volumetric dilutions.

RESULTS

The flow cytometry technique was successful in determining population centiles for concentrations of endometrial lymphocyte subsets. Distinct differences were noted across the patient groups. Th2 concentrations were significantly higher in the controls (p = 0.0002). All RPL/infertile populations had increased concentrations of peripheral type NK's (p = 0.016) and B cells (p = 0.045). Relative to male factor controls, CD4+ and CD8+ T lymphocyte populations were increased in RPL patients, and reduced in those with a history of RIF. Th1 concentrations were elevated in the adverse outcome groups (p = 0.032). Concentration centiles alone do not appear to accurately predict outcome with subsequent treatment.

CONCLUSIONS

Endometrial biopsy analysis by flow cytometry can provide detailed analysis of constituent lymphocyte subsets by concentration as well as proportion. This novel approach provides additional independent data to further assess the significance of endometrial changes in the setting of reproductive failure.

MicroRNAs in Preeclampsia

Preeclampsia (PE) continues to represent a worldwide problem and challenge for both clinicians and laboratory-based doctors. Despite many efforts, the knowledge acquired regarding its pathogenesis and pathophysiology does not allow us to treat it efficiently. It is not possible to arrest its progressive nature, and the available therapies are limited to symptomatic treatment. Furthermore, both the diagnosis and prognosis are frequently uncertain, whilst the ability to predict its occurrence is very limited. MicroRNAs are small non-coding RNAs discovered two decades ago, and present great interest given their ability to regulate almost every aspect of the cell function. A lot of evidence regarding the role of miRNAs in pre-eclampsia has been accumulated in the last 10 years. Differentially expressed miRNAs are characteristic of both mild and severe PE. In many cases they target signaling pathway-related genes that result in altered processes which are directly involved in PE. Immune system, angiogenesis and trophoblast proliferation and invasion, all fundamental aspects of placentation, are controlled in various degrees by miRNAs which are up- or downregulated. Finally, miRNAs represent a potential therapeutic target and a diagnostic tool.

The Role of Extracellular Vesicles and PIBF in Embryo-Maternal Immune-Interactions

Pregnancy represents a unique immunological situation. Though paternal antigens expressed by the conceptus are recognized by the immune system of the mother, the immune response does not harm the fetus. Progesterone and a progesterone induced protein; PIBF are important players in re-adjusting the functioning of the maternal immune system during pregnancy. PIBF expressed by peripheral pregnancy lymphocytes, and other cell types, participates in the feto-maternal communication, partly, by mediating the immunological actions of progesterone. Several splice variants of PIBF were identified with different physiological activity. The full length 90 kD PIBF protein plays a role in cell cycle regulation, while shorter splice variants are secreted and act as cytokines. Aberrant production of PIBF isoforms lead to the loss of immune-regulatory functions, resulting in and pregnancy failure. By up regulating Th2 type cytokine production and by down-regulating NK activity, PIBF contributes to the altered attitude of the maternal immune system. Normal pregnancy is characterized by a Th2-dominant cytokine balance, which is partly due to the action of the smaller PIBF isoforms. These bind to a novel form of the IL-4 receptor, and induce increased production of IL-3, IL-4, and IL-10. The communication between the conceptus and the mother is established via extracellular vesicles (EVs). Pre-implantation embryos produce EVs both in vitro, and in vivo. PIBF transported by the EVs from the embryo to maternal lymphocytes induces increased IL-10 production by the latter, this way contributing to the Th2 dominant immune responses described during pregnancy.

ART implantation failure and miscarriage in patients with elevated intracellular cytokine ratios: response to immune support therapy

Background

The origins of adverse reproductive outcome can be multifactorial, but the contribution of the maternal immune system is considered debatable. Elevated intracellular cytokine ratios have been proposed, although not universally supported, as a marker for immunological dysfunction in implantation and early pregnancy. Poor patient selection or inadequate treatment or testing may be confounding factors. Specific immunomodulation, in carefully selected sub-populations of ART patients with poor reproductive history, despite transfer of good quality blastocysts, may potentially improve clinical outcomes.

Methods

Intracellular cytokine ratios (CKR) were prospectively assessed in 337 patients presenting with a history of implantation failure and/or pregnancy loss, prior to further treatment, and were found to be elevated in 150 (44.5%). Of this group, 134 agreed to initiate a standardised immunotherapy regime (nutraceuticals, prednisolone & intralipids) to evaluate the efficacy of this proposed therapy. Of the intervention population, a small cohort (n = 70) delayed commencing ART for ~ 10 weeks to assess if extended pre-treatment nutraceutical supplementation could normalise CKRs prior to starting ART, and if this conferred additional benefit.

Results

Baseline assessment in the intervention population (n = 134) identified 160 miscarriages from 180 total pregnancies (89% miscarriage rate, MR), conceived both spontaneously and by assisted reproduction. Post-treatment analysis of subsequent ART cycles revealed a significant improvement in both implantation (OR 3.0, 2.0-4.5) and miscarriage rates (41/97, 42.2% MR, P < 0.001). Interestingly, pre-treatment normalisation of CKRs appeared to impart marginal extra benefit prior to subsequent fertility treatment with immunotherapy.

Conclusions

Following immunomodulation, significant improvements in both implantation rate and miscarriage rate were seen in this poor prognosis population. This suggests a possible role for both detailed immuno-evaluation of patients with poor reproductive history with good embryo quality, and application of personalised immunotherapy regimes alongside ART in selected cases. Future randomised controlled trials are needed to definitively evaluate this potentially promising therapeutic approach.

Detailed endometrial immune assessment of both normal and adverse reproductive outcome populations

PURPOSE

Using a comprehensive flow cytometric panel, do endometrial immune profiles in adverse reproductive outcomes such as repeat implantation failure (RIF) and repeat pregnancy loss (RPL) differ from each other and male-factor controls?

METHODS

Six-hundred and twelve patients had an endometrial biopsy to assess the immunophenotype. History on presentation was used to subdivide the population into recurrent implantation failure (RIF) [n = 178], recurrent pregnancy loss (RPL) [n = 155], primary infertility [n = 130] and secondary infertility [n = 114]. A control group was utilised for comparative purposes [n = 35] and lymphocyte subpopulations were described.

RESULTS

Distinct lymphocyte percentage differences were noted across the populations. Relative to controls and RPL, patients with a history of RIF had significantly raised uterine NKs (53.2 vs 45.2 & 42.9%, p < 0.0001). All sub-fertile populations had increased percentage peripheral type NKs (p = 0.001), and exhibited increased CD69+ activation (p = 0.005), higher levels of B cells (p < 0.001), elevated CD4:CD8 ratio (p < 0.0001), lower T-regs (p = 0.034) and a higher proportion of Th1+ CD4s (p = 0.001). Patient aetiology confers some distinct findings, RPL; pNK, Bcells and CD4 elevated; RIF; uNK and CD56 raised while CD-8 and NK-T lowered.

CONCLUSIONS

Flow cytometric endometrial evaluation has the ability to provide a rapid and objective analysis of lymphocyte subpopulations. The findings show significant variations in cellular proportions of immune cells across the patient categories relative to control tissue. The cell types involved suggest that a potential differential pro-inflammatory bias may exist in patients with a history of adverse reproductive outcomes. Immunological assessment in appropriate populations may provide insight into the underlying aetiology of some cases of reproductive failure.

Anti-oxidant mediated normalisation of raised intracellular cytokines in patients with reproductive failure

Background

Raised intracellular cytokine ratios (CKR) are proposed as a significant risk factor for adverse reproductive outcome. An elevated cytokine ratio, such as between TNFa and/or IFNg to IL-10 is associated with recurrent miscarriage (RM). The use of pharmacological immunomodulators such as TNFα inhibitors in these patients is controversial and not generally recommended due to a lack of conclusive data supporting their use. We evaluated whether the use of anti-oxidants/dietary supplements as an alternative could positively influence CKR’s in ART patients.

Methods

A prospective non-placebo control trial of antioxidant treatment for abnormal peripheral inflammatory cytokine ratios was performed. CKRs were assessed using flow cytometry in stimulated versus unstimulated whole blood samples in 337 IVF patients presenting with a previous history of poor outcome (RM or implantation failure). CKR’s were found to be elevated in 150/337. 70/150 patients in this elevated group agreed to a 10 week regime of Omega 3, vitamin D3, and B complex, followed by retesting to evaluate effect.

Results

Mean cytokine ratios significantly improved between tests. Pre-treatment TNFa:IL-10 ratio improved from 71.6 to 21.0 (p < 0.0001) and IFNg:IL-10 ratio dropped from 24.5 to 12.5 (p < 0.0001). The improved ratios were achieved primarily by an increase in IL-10 expression (P = 0.0007), but also by a moderate decrease in stimulated TNFa expression (p = 0.008). Mean IFNg expression was unchanged (p = 0.42). On an individual basis CKR levels were normalised in 43 patients, improved in 12 and remained unchanged in 15. No significant differences in improvement were found between RM and IF subgroups.

Conclusions

Intracellular cytokine expression levels and ratios were modifiable by the supplement regime employed. Elevated cytokine ratios have been linked with adverse reproductive outcomes, and proposed treatments have included biological immunomodulators which antagonise TNFa, but come with significant associated cost implications and more importantly, cytotoxic side-effects. A dietary regime is more patient friendly and lower risk, while still achieving a similar effect in many patients.

The Role of Progesterone in Feto-Maternal Immunological Cross Talk

This review aims to provide a brief historical overview of the feto-maternal immunological relationship, which profoundly influences the outcome of pregnancy. The initial question posed in the 1950s by Medawar [Symp Soc Exp Biol. 1953; 7: 320-338] was based on the assumption that the maternal immune system recognizes the fetus as an allograft. Indeed, based on the association between HLA-matching and spontaneous miscarriage, it became obvious that immunological recognition of pregnancy is required for a successful gestation. The restricted expression of polymorphic HLA antigens on the trophoblast, together with the presence of nonpolymorphic MHC products, excludes recognition by both T and NK cells of trophoblast-presented antigens; however, γδ T cells, which constitute the majority of decidual T cells, are likely candidates. Indeed, a high number of activated, progesterone receptor-expressing γδ T cells are present in the peripheral blood of healthy pregnant women and, in the presence of progesterone, these cells secrete an immunomodulatory protein called progesterone-induced blocking factor (PIBF). As early as in the peri-implantation period, the embryo communicates with the maternal immune system via PIBF containing extracellular vesicles. PIBF contributes to the dominance of Th2-type reactivity which characterizes normal pregnancy by inducing increased production of Th2 cytokines. The high expression of this molecule in the decidua might be one of the reasons for the low cytotoxic activity of decidual NK cells.

KIR, LILRB and their Ligands' Genes as Potential Biomarkers in Recurrent Implantation Failure

Reproductive failure in humans is a very important social and economic problem, because nowadays women decide to conceive later in life and delay motherhood. Unfortunately, with increasing age they have less chance for natural fertilization and maintenance of pregnancy. Many of them need assisted reproductive technology. Approximately 10% of women after in vitro fertilization-embryo transfers experience recurrent implantation failure (RIF). Multiple factors may contribute to RIF, including oocyte and sperm quality, parental chromosomal anomalies, genetic or metabolic abnormalities of the embryo, poor uterine receptivity, immunological disturbances in the implantation site, and some gynecologic pathologies such as endometriosis, uterine fibroids, hydrosalpinx and endometrial polyps. Moreover, the procedure of in vitro fertilization itself could adversely influence the implantation. Nowadays, many studies are focused on the role of natural killer (NK) cells in normal and pathologic pregnancy because NK cells constitute the dominant cell population in the endometrium and they come in close contact with the allogeneic extravillous trophoblast cells in early pregnancy decidua. The majority of these cells are of CD56^bright phenotype. These cells can express killer immunoglobulin-like receptors (KIRs), which, upon recognition of HLA class I molecules (HLA-C and HLA-G) on trophoblasts, may either stimulate or inhibit NK cells to produce soluble factors, and display low cytotoxicity necessary for maintenance of the allogeneic embryo and fetus in the next steps of pregnancy. Moreover, some members of the leukocyte immunoglobulin-like receptor (LILR) family, also named ILT (immunoglobulin-like transcript), are present in the human placenta. LILRB1 (ILT2) was described mainly on stromal cells, while LILRB2 (ILT4), in addition to stromal cells, was also found around vessels in the smooth muscle layer. In this review we focus on the possible role of polymorphism of KIR, LILRB and their ligands (HLA-C, HLA-G) in susceptibility to recurrent implantation failure, which could serve as diagnostic biomarkers of this disease.

Uterine CD56dim and CD16+ Cells in Refractory Antiphospholipid Antibody-Related Pregnancy Loss and Chromosomally Intact Abortuses: A Case-Control Study

AIM

To evaluate the role of uterine natural killer (uNK) CD56^dim and CD16⁺ cells in patients with refractory antiphospholipid, antibody-mediated, recurrent, pregnancy loss.

SETTINGS AND DESIGN

A case-control study was conducted between 2012 and 2015 at a university hospital.

PATIENTS AND METHODS

A group of 118 women with a history of antiphospholipid antibody syndrome experiencing fetal loss in spite of low dose aspirin (LDA) and low molecular weight heparin (LMWH) treatment in the current pregnancy were included in this study. A group of 32 patients undergoing an elective termination of viable pregnancies before 20 weeks were taken as controls. Suction evacuation was performed to collect abortus specimens, and uterine wall curettage was performed to collect decidua specimens, which were then stained using monoclonal antibodies specific to CD56 and CD16.

STATISTICS

Statistical analyses were performed using the Statistical Package for the Social Sciences version 18 software. Chi-square and Fisher exact tests were used for making comparison between the groups.

RESULTS

Abnormal fetal karyotype was found in nine (9/97) cases of the study group, which means that abnormal karyotype accounts for only 9.3% of the causes of failure of treatment. Abnormal karyotype was found in four cases of the control group. Only cases with normal karyotyping were subjected to decidual uNK cells analysis. We found that CD56^dim and CD16⁺ were found in the decidua of 79 cases (79/97), which means that aberrant natural killer cells expression might account for 81.4% of the cases of refractory antiphospholipid antibody (APA)-mediated recurrent pregnancy loss.

CONCLUSION

CD56^dim and CD16⁺ uNK cells might be correlated with refractory APA-mediated recurrent pregnancy loss.

PIBF positive uterine NK cells in the mouse decidua

Though uterine NK cells (u NK cells) contain cytotoxic granules, and selectively over- express the genes of perforin and granzymes, during normal pregnancy, they are not cytotoxic. Progesterone is indispensable for the establishment and maintenance of pregnancy both in humans and in mice. Mouse uterine NK cells do not express the classical progesterone receptor, yet progesterone affects the recruitment and function of uterine NK cells, the latter partly via the Progesterone-Induced Blocking Factor (PIBF). We demonstrated PIBF positive granulated cells in the mouse decidua. The aim of this study was to characterize these cells by lectin immunohistochemistry and anti-perforin reactivity. PIBF+ granulated cells were absent from the deciduae of alymphoid mice, but appeared in the decidua of those that had been reconstituted with bone marrow from male BALB/c mice. PIBF+ granulated cells bound the DBA lectin, suggesting their NK cell nature, and also contained perforin, which co-localized with PIBF in the cytoplasmic granules. In anti-progesterone treated mice all of the PIBF+ cells were perforin positive at g. d. 12.5, in contrast to the 54% perforin positivity of PIBF+ cells in untreated mice.

CONCLUSION

The PIBF+ granulated cells in the decidua belong to the NK population, and PIPB co-localizes with perforin in the cytoplasmic granules.

Decidual CD56+ Natural Killer Cells in Spontaneous Early Pregnancy Loss- An Immunohistochemical Study

INTRODUCTION

Natural killer cells are believed to promote placental and trophoblastic growth and provide immune- modulation at maternal-fetal interface in pregnancy and their role in reproductive failure has been a matter of discussion.

AIM

To study CD56+ Natural killer cells in spontaneous pregnancy loss.

MATERIALS AND METHODS

In this prospective observational study, formalin-fixed paraffin embedded sections from products of conception from twenty women each with spontaneous early pregnancy loss (test group) and elective pregnancy termination (control group). Immunohistochemical staining with CD 56 monoclonal antibody was done by avidin-biotin peroxidase technique. CD56+ cells in decidua were counted under light microscopy by two independent observers in ten high power fields (40X) and mean cell count taken. Student's paired 't'-test was used to statistically compare CD56+ NK cell population between the test and control groups.

RESULTS

The mean number of CD56+ NK cells was higher in the decidual tissue of women who had spontaneous early pregnancy loss (mean±SD, 57.55±1.79) as compared to the mean number of CD56+ NK cells in the decidual tissue from women who underwent elective termination (mean±SD, 50.9±3.46). The difference was statistically significant (difference of 6.65 with 95% confidence interval of 4.76 to 8.54, p-value <0.0001).

CONCLUSION

This could imply that CD56+ NK cells have a role in the pathogenesis of spontaneous early pregnancy loss and further large scale studies can throw more light on the mechanism and designing of appropriate therapy.

Relationship between uterine natural killer cells and unexplained repeated miscarriage

OBJECTIVE

To evaluate the relation between uterine killer (uK) cells and unexplained repeated miscarriage (RM).

MATERIAL AND METHODS

Eighty women with unexplained repeated miscarriage and missed miscarriage of current pregnancy were studied. Fetal viability and gestational age of the current pregnancy were confirmed by ultrasound, followed by suction evacuation to collect abortion specimens and uterine wall curettage to collect decidua specimens. Abortion specimens were collected for long-term monolayer cell culture and subsequent chromosome analysis using conventional G-banding. Decidua specimens were subjected to immunohistochemical staining using monoclonal antibodies specific to CD56+ and CD16+ expressed by uK cells.

RESULTS

CD56+ CD16+ uK cells were found in 85% [68/80] of the studied decidua specimens of women with unexplained repeated miscarriage; 88.5% [54/61] had normal abortion karyotyping and 73.7% [14/19] had abnormal abortion karyotyping. Moreover, 73.75% [59/80] of the studied women with a past history of early miscarriage had CD56+ CD16+ uK cells in their decidua specimens, and 66.25% [53/80] of studied women with a past history of late miscarriage had CD56+ CD16+ uK cells in their decidua specimens; the association between early and late miscarriage and CD56+ CD16+ uK cells in decidua specimens was significant.

CONCLUSION

CD56+CD16+ uK cells were predominant in the decidua specimens of the studied women with repeated miscarriage. A significant association was found between the presence of CD56+ CD16+ uK cells in the studied decidua specimens and unexplained repeated miscarriage.

Immunological role of vitamin D at the maternal-fetal interface

During pregnancy, immune activity is tightly regulated so that antimicrobial protection of the mother and fetus is balanced with the need for immune tolerance to prevent fetal rejection. In this setting, the maternal-fetal interface, in the form of the uterine decidua, provides a heterogeneous immune cell population with the potential to mediate diverse activities throughout pregnancy. Recent studies have suggested that vitamin D may be a key regulator of immune function during pregnancy, with the fetal-maternal interface representing a prominent target. Among its non-classical actions are potent immunomodulatory effects, including induction of antibacterial responses and modulation of T-lymphocytes to suppress inflammation and promote tolerogenesis. Thus, vitamin D may play a pivotal role in normal decidual immune function by promoting innate responses to infection, while simultaneously preventing an over-elaboration of inflammatory adaptive immunity. Research to date has focused upon the potential role of vitamin D in preventing infectious diseases such as tuberculosis, as well as possibly suppressing of autoimmune disease. Nevertheless, vitamin D may also influence facets of immune function not immediately associated with primary innate responses. This review summarises our current understanding of decidual immune function with respect to the vitamin D metabolism and signalling, and as to how this may be affected by variations in maternal vitamin D status. There has recently been much interest in vitamin D supplementation of pregnant women, but our knowledge of how this may influence the function of decidua remains limited. Further insight into the immunomodulatory actions of vitamin D during pregnancy will help shed light upon this.

Ultrastructure alteration of decidual natural killer cells in women with unexplained recurrent miscarriage: a possible association with impaired decidual vascular remodelling

This study aimed to evaluate the extent of remodelling of intra-decidual segments of the spiral arteries in human deciduas between the 6th and 10th gestational weeks in women with unexplained recurrent miscarriages (RM) in comparison to gestational-matched controls. A possible association with the number, immunoexpressive behaviour and ultrastructural changes of decidual natural killer cells (dNKCs) was investigated. Decidual biopsies were obtained from RM cases (n = 40) and women with no history of spontaneous miscarriage and at least one live birth at term (n = 30). Staining was performed using PAS, anti-CD34 and anti-CD56 antibodies, using an avidin-biotin-peroxides technique. Analysis by means of light and transmission electron microscopy was employed. To determine the extent of remodelling of decidual vessels, a quantitative score was analysed using histological criteria of vascular transformation and then related to the number of CD56(+) dNKCs. In RM, dNKCs were distributed among decidual cells and around the vessels. They possessed numerous polyploidic protrusions on cell membranes crossing from one cell to another. The cells became more irregular and exhibited heterogeneous electron-dense granules in their cytoplasm compared to controls. The non-remodelling score and number of dNKCs were significantly increased in RM group (p < 0.001). The number of dNKCs was significantly correlated with the scores in both control (r = 0.491; p = 0.006) and RM (r = 0.852; p < 0.001) groups. It appears that dNKCs play a key role in impaired decidual artery remodelling that may be involved with early RM. This may be due to increased numbers of cells or impaired cellular interactions resulting from alterations to the ultrastructure.

In-vitro model systems for the study of human embryo-endometrium interactions

Implantation requires highly orchestrated interactions between the developing embryo and maternal endometrium. The association between abnormal implantation and reproductive failure is evident, both in normal pregnancy and in assisted reproduction patients. Failure of implantation is the pregnancy rate-limiting step in assisted reproduction, but, as yet, empirical interventions have largely failed to address this problem. Better understanding of the mechanisms underlying human embryo-endometrium signalling is a prerequisite for the further improvement of assisted reproduction outcomes and the development of effective interventions to prevent early pregnancy loss. Studying human embryo implantation is challenging since in-vivo experiments are impractical and unethical, and studies in animal models do not always translate well to humans. However, in recent years in-vitro models have been shown to provide a promising way forward. This review discusses the principal models used to study early human embryo development and initial stages of implantation in vitro. While each model has limitations, exploiting these models will improve understanding of the molecular mechanisms and embryo-endometrium cross-talk at the early implantation site. They provide valuable tools to study early embryo development and pathophysiology of reproductive disorders and have revealed novel disease mechanisms such as the role of epigenetic modifications in recurrent miscarriage.

DBA-lectin reactivity defines mouse uterine natural killer cell subsets with biased gene expression

Endometrial decidualization, a process essential for blastocyst implantation in species with hemochorial placentation, is accompanied by an enormous but transient influx of natural killer (NK) cells. Mouse uterine NK (uNK) cell subsets have been defined by diameter and cytoplasmic granule number, reflecting stage of maturity, and by histochemical reactivity with Periodic Acid Schiff (PAS) reagent with or without co-reactivity with Dolichos biflorus agglutinin (DBA) lectin. We asked whether DBA- and DBA+ mouse uNK cells were equivalent using quantitative RT-PCR analyses of flow-separated, midpregnancy (Gestation Day [gd] 10) cells and immunohistochemistry. CD3E (CD3)-IL2RB (CD122)+DBA cells were identified as the dominant Ifng transcript source. Skewed IFNG production by uNK cell subsets was confirmed by analysis of uNK cells from eYFP-tagged IFNG-reporter mice. In contrast, CD3E-IL2RB+DBA+ uNK cells expressed genes compatible with significantly greater potential for IL22 synthesis, angiogenesis, and participation in regulation mediated by the renin-angiotensin system (RAS). CD3E-IL2RB+DBA+ cells were further divided into VEGFA+ and VEGFA- subsets. CD3E-IL2RB+DBA+ uNK cells but not CD3E-IL2RB+DBA- uNK cells arose from circulating, bone marrow-derived progenitor cells by gd6. These findings indicate the heterogeneous nature of mouse uNK cells and suggest that studies using only DBA+ uNK cells will give biased data that does not fully represent the uNK cell population.

Immunomorphological changes in the rhesus monkey endometrium and decidua during the menstrual cycle and early pregnancy

PROBLEM

Throughout the reproductive cycle and into early pregnancy, the normal endometrium undergoes changes in a range of leukocytes, epithelia, stromal fibroblasts, and vascular structures caused by intersecting effects of hormone balance and embryo implantation. The direct investigation in humans of reproductive tract responses during normal and physiologically altered cycles is not practical or feasible. METHOD AND STUDY: The aim of this study was to define immunological and morphological changes through immunohistological and morphometric evaluation of the endometrium throughout the menstrual cycle and the decidua during early gestation in the rhesus monkey, a tractable experimental animal model.

RESULTS

A zone-dependent method for the immunohistological description of the rhesus uterine mucosa was established and showed that leukocyte infiltration, stromal cell decidualization, glandular and vascular responses were zone- and cell type-dependent, and changed throughout the cycle and early pregnancy. Morphological heterogeneity of uterine natural killer cells in the cycling endometrium and gestational decidua were consistent with the recent characterization of phenotypic subsets.

CONCLUSIONS

These data establish a morphological platform upon which to further study the regulation of endometrial responses to the hormonal mileau of pregnancy, the control of local leukocyte populations, and the responses to threatened pregnancy, infection, and inflammation.

Impaired decidual natural killer cell regulation of vascular remodelling in early human pregnancies with high uterine artery resistance

During human pregnancy, natural killer (NK) cells accumulate in the maternal decidua, but their specific roles remain to be determined. Decidual NK (dNK) cells are present during trophoblast invasion and uterine spiral artery remodelling. These events are crucial for successful placentation and the provision of an adequate blood supply to the developing fetus. Remodelling of spiral arteries is impaired in the dangerous pregnancy complication pre-eclampsia. We studied dNK cells isolated from pregnancies at 9–14 weeks' gestation, screened by uterine artery Doppler ultrasound to determine resistance indices which relate to the extent of spiral artery remodelling. dNK cells were able to promote the invasive behaviour of fetal trophoblast cells, partly through HGF. Cells isolated from pregnancies with higher resistance indices were less able to do this and secreted fewer pro-invasive factors. dNK cells from pregnancies with normal resistance indices could induce apoptotic changes in vascular smooth muscle and endothelial cells in vitro, events of importance in vessel remodelling, partly through Fas signalling. dNK cells isolated from high resistance index pregnancies failed to induce vascular apoptosis and secreted fewer pro-apoptotic factors. We have modelled the cellular interactions at the maternal-fetal interface and provide the first demonstration of a functional role for dNK cells in influencing vascular cells. A potential mechanism contributing to impaired vessel remodelling in pregnancies with a higher uterine artery resistance is presented. These findings may be informative in determining the cellular interactions contributing to the pathology of pregnancy disorders where remodelling is impaired, such as pre-eclampsia.

Copyright © 2012 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

Assessment of endometrial receptivity

OBJECTIVE

To provide a focused review of the scientific literature pertaining to endometrial receptivity.

DESIGN

Review of the literature and appraisal of relevant articles.

SETTING

Academic teaching hospital.

PATIENT(S)

Women with infertility.

INTERVENTION(S)

None.

MAIN OUTCOME MEASURE(S)

Critical review of the literature.

RESULT(S)

Although a consensus has been achieved regarding the existence of a temporally defined period during which embryo attachment and invasion can occur (called the "window of implantation"), reliable methods to assess "receptivity" have not been established or adequately validated. In women with certain gynecologic disorders, including endometriosis, tubal disease, and polycystic ovary syndrome, endometrial receptivity seems to be compromised, leading to infertility and pregnancy loss. The establishment of reliable biomarkers for the detection of defects in endometrial receptivity has been a long-sought goal that remains an elusive target. The validation of endometrial biomarkers will require properly designed and implemented studies based on the recognition that endometrial receptivity defects are not equally distributed in women with endometriosis or these other conditions.

CONCLUSION(S)

Rapidly advancing technologies are bringing new biomarkers to the clinical arena that promise to further reveal the complexities of the implantation process.

Prednisolone treatment reduces endometrial spiral artery development in women with recurrent miscarriage

BACKGROUND

Uterine natural killer (uNK) cells and endometrial blood vessel maturation are increased in the luteal phase of the menstrual cycle in a subset of women with recurrent miscarriage (RM). uNK cell numbers are reduced after treatment with prednisolone (20 mg/day for 3 weeks).

HYPOTHESES

Prednisolone treatment reduces endometrial vascular maturation and angiogenic growth factor expression in women with RM with increased uNK cells.

METHODS

Endometrial biopsies (n = 18 paired samples) from women with RM at LH + 7 before and during prednisolone treatment (20 mg/day for 3 weeks) were snap frozen. Total RNA and cDNA was prepared and used in a human angiogenesis RT-PCR superarray (84 genes, n = 6 pairs) with results validated using RT-PCR (n = 15 pairs). Immunohistochemistry (n = 15 pairs) was performed for Factor VIII, α-smooth muscle actin (α-SMA) and myosin heavy chain (MyHC) and the total number of vessels and the percentage of vessels completely surrounded by vascular smooth muscle cells (VSMCs) were determined.

RESULTS

During prednisolone treatment there was no change in the total number of endometrial blood vessels but the percentage of vessels completely surrounded by VSMCs was decreased (α-SMA P < 0.0001; MyHC P < 0.0001). Endometrial EGF and STAB 1 expression was decreased during prednisolone treatment in samples from woman who went on to have a live birth.

CONCLUSIONS

The effect of prednisolone therapy for some women with RM may be due to altered endometrial angiogenic growth factor expression and reduced blood vessel maturation.

ITI-H4, as a biomarker in the serum of recurrent pregnancy loss (RPL) patients

Recurrent pregnancy loss (RPL) is defined as at least three pregnancy losses in series prior to the 20-28 weeks of pregnancy. There are several etiological factors associated with immunology, anatomy, endocrinology, genetic, infection, chromosomal abnormalities, and environmental factors contributing to the condition. The aim of this study was to identify RPL associated factors in human blood using proteomics. Since it is difficult to obtain tissues or follicular fluids, we used blood samples from normal and RPL patients to conduct a comparative proteomic study. Three RPL blood samples and one cocktailed blood sample from 3 normal women were used. We performed 2-DE and selected spots were analyzed with MALDI-TOF/MS. In the three RPL blood samples, 2-DE analysis revealed 549, 563 and 533 spots to be differentially expressed, respectively. Through a comparative analysis between the control and RPL, 21 spots were shown to be differentially expressed. Of these, 5 proteins were confirmed by Western blot analysis. One of these proteins, ITI-H4 (inter-α trypsin inhibitor-heavy chain 4), was weakly expressed at a molecular weight of 120 kDa, but was highly expressed at a modified molecular weight of 36 kDa in RPL patients. These findings suggest that ITI-H4 expression may be used as a biomarker, which could facilitate the development of novel diagnostic and therapeutic tools.

Subfertility linked to combined luteal insufficiency and uterine progesterone resistance

Early pregnancy loss is common and can be caused by a range of factors. The Brown Norway (BN) rat exhibits reproductive dysfunction characterized by small litter size and pregnancy failure and represents a model for investigating early pregnancy loss. In this study, we investigated the establishment of pregnancy in the BN rat and gained insight into mechanisms causing its subfertility. Early stages of BN uteroplacental organization are unique. The BN primordial placenta is restricted in its development and correlates with limited BN uterine decidual development. BN uterine decidua was shown to be both structurally and functionally distinct and correlated with decreased circulating progesterone (P4) levels. Ovarian anomalies were also apparent in BN rats and included decreased ovulation rates and decreased transcript levels for some steroidogenic enzymes. Attempts to rescue the BN uterine decidual phenotype with steroid hormone therapy were ineffective. BN uteri were shown to exhibit reduced responsiveness to P4 but not to 17beta-estradiol. P4 resistance was associated with decreased transcript levels for the P4 receptor (Pgr), a P4 receptor chaperone (Fkbp4), and P4 receptor coactivators (Ncoa1 and Ncoa2). In summary, the BN rat exhibits luteal insufficiency and uterine P4 resistance, which profoundly affects its ability to reproduce.

Pre-eclampsia: fitting together the placental, immune and cardiovascular pieces

The success of pregnancy is a result of countless ongoing interactions between the placenta and the maternal immune and cardiovascular systems. Pre-eclampsia is a serious pregnancy complication that arises from multiple potential aberrations in these systems. The pathophysiology of pre-eclampsia is established in the first trimester of pregnancy, when a range of deficiencies in placentation affect the key process of spiral artery remodelling. As pregnancy progresses to the third trimester, inadequate spiral artery remodelling along with multiple haemodynamic, placental and maternal factors converge to activate the maternal immune and cardiovascular systems, events which may in part result from increased shedding of placental debris. As we understand more about the pathophysiology of pre-eclampsia, it is becoming clear that the development of early- and late-onset pre-eclampsia, as well as intrauterine growth restriction (IUGR), does not necessarily arise from the same underlying pathology.

Do molecular signals from the conceptus influence endometrium decidualization in rodents?

A critical period in establishing pregnancy occurs after the onset of implantation but before placental development. Evidence strongly suggests that abnormalities occurring during this period can result in pregnancy termination or in pre-eclampsia; the latter may lead to small-for-gestational-weight offspring that are likely to be unhealthy. Clearly, events occurring in the endometrium during the implantation process are crucial for proper fetal development and for optimal offspring health. In several mammalian species bi-directional communication between the conceptus and endometrium during implantation is required for successful pregnancy. Although different implantation and placentation modes occur in different mammalian species, common aspects of this bi-directional signaling may exist. The molecular signals from the trophoblast cells of the conceptus, which direct endometrial changes during implantation progression, are well known in some nonrodent species. Currently, we know little about such signaling in rodents during implantation progression, when the endometrium undergoes decidualization. This review focuses on data that support the hypothesis that paracrine signals from the rodent conceptus influence decidualization. Where possible, these findings are compared and contrasted with information currently known in other species that exhibit different implantation modes.