Review of factors essential for blastocyst implantation for their modulating effects on the maternal immune system

New immune horizons in therapeutics and diagnostic approaches to Preeclampsia

Hypertensive disorders of pregnancy (HDP) are one of the commonest maladies, affecting 5%-10% of pregnancies worldwide. The American College of Obstetricians and Gynecologists (ACOG) identifies four categories of HDP, namely gestational hypertension (GH), Preeclampsia (PE), chronic hypertension (CH), and CH with superimposed PE. PE is a multisystem, heterogeneous disorder that encompasses 2%-8% of all pregnancy-related complications, contributing to about 9% to 26% of maternal deaths in low-income countries and 16% in high-income countries. These translate to 50 000 maternal deaths and over 500 000 fetal deaths worldwide, therefore demanding high priority in understanding clinical presentation, screening, diagnostic criteria, and effective management. PE is accompanied by uteroplacental insufficiency leading to vascular and metabolic changes, vasoconstriction, and end-organ ischemia. PE is diagnosed after 20 weeks of pregnancy in women who were previously normotensive or hypertensive. Besides shallow trophoblast invasion and inadequate remodeling of uterine arteries, dysregulation of the nonimmune system has been the focal point in PE. This results from aberrant immune system activation and imbalanced differentiation of T cells. Further, a failure of tolerance toward the semi-allogenic fetus results due to altered distribution of Tregs such as CD4+FoxP3+ or CD4+CD25+CD127(low) FoxP3+ cells, thereby creating a cytotoxic environment by suboptimal production of immunosuppressive cytokines like IL-10, IL-4, and IL-13. Also, intracellular production of complement protein C5a may result in decreased FoxP3+ regulatory T cells. With immune system dysfunction as a major driver in PE pathogenesis, it is logical that therapeutic targeting of components of the immune system with pharmacologic agents like anti-inflammatory and immune-modulating molecules are either being used or under clinical trial. Cholesterol synthesis inhibitors like Pravastatin may improve placental perfusion in PE, while Eculizumab (monoclonal antibody inhibiting C5) and small molecular inhibitor of C5a, Zilucoplan are under investigation. Monoclonal antibody against IL-17(Secukinumab) has been proposed to alter the Th imbalance in PE. Autologous Treg therapy and immune checkpoint inhibitors like anti-CTLA-4 are emerging as new candidates in immune horizons for PE management in the future.

Sex Hormones as Key Modulators of the Immune Response in Multiple Sclerosis: A Review

BACKGROUND

A variety of autoimmune diseases, including MS, amplify sex-based physiological differences in immunological responsiveness. Female MS patients experience pathophysiological changes during reproductive phases (pregnancy and menopause). Sex hormones can act on immune cells, potentially enabling them to modify MS risk, activity, and progression, and to play a role in treatment.

METHODS

Scientific papers (published between 1998 and 2021) were selected through PubMed, Google Scholar, and Web of Science literature repositories. The search was limited to publications analyzing the hormonal profile of male and female MS patients during different life phases, in particular focusing on sex hormone treatment.

RESULTS

Both men and women with MS have lower testosterone levels compared to healthy controls. The levels of estrogens and progesterone increase during pregnancy and then rapidly decrease after delivery, possibly mediating an immune-stabilizing process. The literature examined herein evidences the neuroprotective effect of testosterone and estrogens in MS, supporting further examinations of their potential therapeutic uses.

CONCLUSIONS

A correlation has been identified between sex hormones and MS clinical activity. The combination of disease-modifying therapies with estrogen or estrogen plus a progestin receptor modulator promoting myelin repair might represent an important strategy for MS treatment in the future.

Regulatory Effects of Fyn on Trophoblast Cell Behaviors and Function

Fyn has been proven to be involved in various cell behaviors and pathophysiological processes. However, the expression and roles of Fyn in trophoblasts remain unclear. Here, we aimed to evaluate the participation of Fyn in trophoblast behavior and function, and the related mechanisms were briefly explored. Fyn expression in the HTR-8/SVneo, JEG-3, and JAR cell lines was evaluated by immunofluorescence, quantitative real-time PCR and western blotting. Fyn expression in human hydatidiform moles was also determined by immunohistochemistry and western blot. To explore the effects of Fyn, HTR-8/SVneo and JEG-3 cells were transfected with Fyn shRNA or overexpression plasmid or treated with the Fyn activity inhibitor SU6656 or ERK1/2 inhibitor U0126. The migration, proliferation, and apoptosis of trophoblast cells were assessed using transwell assays, flow cytometry, and cell counting kit-8 assays, respectively. The production of primary inflammatory cytokines, HLA-G and active matrix metallopeptidase (MMP) 2/9, and the phosphorylation of ERK1/2 and STAT3 were evaluated by ELISA, western blot, or gelatin zymography. The results showed that Fyn was expressed by trophoblast cells, mainly in the cytoplasm and membrane. Fyn expression and activity levels both increased in order from HTR-8/SVneo and JAR to JEG-3. The overexpression of Fyn promoted the proliferation and migration of trophoblast cells and inhibited their apoptosis, while the opposite effects were observed for Fyn knockdown and inhibition. Fyn regulated inflammatory cytokine production in trophoblast cells by promoting TGF-β and IL-4 secretion while inhibiting IFN-γ and TNF-α secretion. Moreover, HLA-G expression in JEG-3 was positively regulated by Fyn. Fyn also facilitated the expression of active MMP2/9 and the activation of ERK1/2 and STAT3. Besides, it was confirmed that Fyn regulated trophoblast cell activities through ERK1/2 signal pathway by using U0126. Our study first detected the expression of Fyn in trophoblast cells. Fyn played pivotal roles in trophoblast cell behaviors and function, ERK1/2 was one of its targets, and MMP2/9 and STAT3 may also be involved in the regulatory mechanism.

Human platelet lysates stimulate in vitro proliferation of human endometrial cells from patients with a history of recurrent implantation failure

OBJECTIVE

To optimize and compare the isolation of platelet-rich plasma (PRP) and its cryopreserved derivative, platelet lysate (PL), to a commercial human platelet lysate (HPL) product PLUS and investigate their proliferative stimulation on primary human endometrial cells in vitro.

DESIGN

Basic research.

SETTING

Academic fertility center.

PATIENT(S)

Three healthy blood donors and eight patients with a history of recurrent implantation failure.

INTERVENTIONS(S)

Stimulated proliferation of isolated primary endometrial epithelial cells and endometrial stromal cells in vitro with autologous and nonautologous HPL (PLUS; Compass Biomedical).

MAIN OUTCOME MEASURE(S)

Platelet-derived growth factor BB homodimer protein content in isolated PRP/PL and commercial HPL and endometrial epithelial cell and endometrial stromal cell proliferation after 24- or 48-hour stimulation with PL (measured by metabolic activity and Ki67 expression).

RESULT(S)

To optimize and compare the isolation of autologous PRP/PL, three double-centrifugation protocols were assessed by flow cytometry for platelet yield (CD45^-CD41⁺CD61⁺) and platelet-derived growth factor BB homodimer protein content by enzyme-linked immunosorbent assay. Cryopreserved PL, especially isolated by our fastest protocol, contained higher protein concentrations and, thus, was optimal for experimental flexibility compared with fresh PRP. The autologous and commercial PLs displayed comparable immune and growth factor content and stimulation of cell proliferation in vitro.

CONCLUSION(S)

Our results provide the groundwork for the isolation and use of HPL to stimulate endometrial growth. Furthermore, commercial PL consistently stimulated cell proliferation and may allow standardization of clinical treatment for recurrent implantation failure.

Trophoblast H2S Maintains Early Pregnancy via Regulating Maternal-Fetal Interface Immune Hemostasis

CONTEXT

Dysregulated immune hemostasis occurs in unexplained recurrent spontaneous abortion (URSA). Synthesized by cystathionine β-synthase (CBS) and cystathionine γ-lyase (CSE), hydrogen sulfide (H2S) promotes regulatory T-cell differentiation and regulates immune hemostasis; yet, its role in URSA is elusive.

OBJECTIVE

To determine if H2S plays a role in early pregnancy and if dysregulated H2S signaling results in recurrent spontaneous abortion.

DESIGN

First trimester placenta villi and decidua were collected from normal and URSA pregnancies. Protein expression was examined by immunohistochemistry and immunoblotting. Human trophoblast HTR8/SVneo and JEG3 cells were treated with H2S donors; HTR8/SVneo cells were transfected with CBS ribonucleic acid interference (RNAi) or complementary deoxyribonucleic acid. Cell migration and invasion were determined by transwell assays; trophoblast transcriptomes were determined by RNA sequencing (RNA-seq). Wild-type, CBS-deficient, and CBA/J × DBA/2 mice were treated with CBS and CSE inhibitors or H2S donors to determine the role of H2S in early pregnancy in vivo.

RESULTS

CBS and CSE proteins showed cell-specific expressions, but only CBS decreased in the villous cytotrophoblast in URSA versus normal participants. H2S donors promoted migration and invasion and MMP-2 and VEGF expression in human placenta trophoblast cells that contain SV40 viral deoxyribonucleic acid sequences (HTR8/SVneo) and human placenta trophoblast cells (JEG3 cells), similar to forced CBS expression in HTR8/SVneo cells. The CBS-responsive transcriptomes in HTR8/SVneo cells contained differentially regulated genes (ie, interleukin-1 receptor and prostaglandin-endoperoxide synthase 2) that are associated with nuclear factor-κB-mediated inflammatory response. In vivo, dysregulated CBS/H2S signaling significantly increased embryonic resorption and decidual T-helper 1/T-helper 2 imbalance in mice, which was partially rescued by H2S donors.

CONCLUSION

CBS/H2S signaling maintains early pregnancy, possibly via regulating maternal-fetal interface immune hemostasis, offering opportunities for H2S-based immunotherapies for URSA.

Association of CD200 expression in paternal lymphocytes with female Th1/Th2 balance and pregnancy establishment at immunotherapy of recurrent spontaneous abortion

PROBLEM

We hypothesized that expression of transmembrane glycoprotein CD200 on paternal lymphocytes used for pre-gestational lymphocyte immunotherapy (LIT) of recurrent spontaneous abortion (RSA) can suppress the pro-inflammatory Th1-type immunity required for successful implantation. To reveal the association between CD200 expression, female immune background after LIT, and pregnancy establishment, we have performed this work.

METHOD OF STUDY

Pre-gestational alloimmunizations were given to 37 women using paternal peripheral blood leukocytes, combined with additional alloimmunizations in case of pregnancy. Lymphocyte phenotypes were determined by flow cytometry. Cytokines produced by mitogen-stimulated female peripheral blood cells were estimated by FlowCytomix™ technology.

RESULTS

We have shown that 78.4% (29/37) of women became pregnant within 12 menstrual cycles after pre-gestational LIT. Pregnancy establishment depends on the intensity of CD200 expression, which is significantly higher on the CD200⁺ lymphocytes administered to women who later did not achieve pregnancy (P < .05). The expression of CD200 negatively correlates with the ratios of Th1/Th2 cytokines produced by female peripheral blood cells (P < .05) and positively correlates with the frequency of female circulating regulatory T cells after LIT (P < .05). The ROC analysis showed that the intensity of CD200 expression and the Th1/Th2 ratios are the significant predictors of pregnancy establishment after pre-gestational LIT (P < .05 and P < .01, respectively).

CONCLUSION

Elevated CD200 expression on allogeneic lymphocytes most likely suppresses the pro-inflammatory Th1-type immunity needed for successful embryo implantation. Therefore, a personalized approach of LIT should be applied to avoid negative effects of such immunomodulation on pregnancy establishment.

ALK3-SMAD1/5 Signaling Mediates the BMP2-Induced Decrease in PGE2 Production in Human Endometrial Stromal Cells and Decidual Stromal Cells

BMP2 is a critical factor that is involved in the processes of embryo implantation and uterine decidualization. The expression of cyclooxygenase (COX) and subsequent prostaglandin E2 (PGE2) production are critical for successful pregnancy. However, it is not clear whether BMP2 can regulate the production of PG during endometrial decidualization. The aim of this study was to investigate the effects of BMP2 on COX-1 expression and PGE2 production as well as the underlying molecular mechanisms in the human endometrium. Immortalized human endometrial stromal cells (HESCs) and human decidual stromal cells (HDSCs) were used as the study model to investigate the effects of BMP2-induced cellular activities. Our results showed that BMP2 treatment significantly decreased PGE2 production by downregulating COX-1 expression in both human endometrial stromal and decidual stromal cells. Additionally, BMP2 induced an increase in the levels of phosphorylated SMAD1/5/8, and this effect was completely abolished by the addition of the inhibitors DMH-1 and dorsomorphin, but not by SB431542. Knocking down ALK3 completely reversed the BMP2-induced downregulation of COX-1. Moreover, concomitantly knocking down SMAD1 and SMAD5 completely reversed the BMP2-induced downregulation of COX-1. Our results indicated that BMP2 decreased PGE2 production by downregulating COX-1 expression, most likely through the ALK3/SMAD1-SMAD5 signaling pathway in human endometrial stromal and human decidual stromal cells. These findings deepen our understanding of the functional role of BMP2 in the regulation of endometrial decidualization in humans.

Upregulation of Toll-like receptor 4 through anti-miR-Let-7a enhances blastocyst attachment to endometrial cells in mice

Despite encouraging advances in fertility technology, the success rate of an ongoing pregnancy is relatively low and predominantly associated with implantation failure. Inflammatory responses are beneficial in the fetomaternal interface and supposedly accelerate the chances for successful implantation. The current study aims to determine the effect of Toll-like receptor 4 (TLR4) overexpression in mouse blastocysts via Let-7a downregulation using intracytoplasmic sperm injection-sperm-mediated gene transfer on embryo attachment rate. The pLenti-III-GFP-miR-Off-Let-7a vector was transmitted to oocytes derived via in vitro maturation (IVM) and in vivo oocytes by using NaOH-treated spermatozoa. Let-7a and TLR4 expression levels were evaluated by quantitative real-time polymerase chain reaction (qRT-PCR), immunocytochemistry, and western blot analysis in both oocytes and embryos. Blastocyst adhesion on the endometrial cells was monitored by microscopic analysis. qRT-PCR results showed that Let-7a expression decreased in the IVM (GV-MII) oocytes compared to the in vivo oocyte (MII) group (p < .05). TLR4 showed a higher expression in GV-MII oocytes at both the gene and protein levels (p < .05). Following anti-miR-Let-7a transmission, the TLR4 expression level was significantly upregulated in embryos compared with the control groups (p < .05). Attachment and migration of trophoblasts cells towards endometrial cells dramatically increased compared to the control group (p < .05). Based on our results, we concluded that Let-7a might mediate embryo attachment through regulation of TLR4 expression levels.

Fertility Treatment Resulting in Live Births in Women with Asthma - Associated with Perennial Allergy?

Background

Asthma has been linked with prolonged time to pregnancy compared to healthy controls, also asthma has been linked to a higher need for fertility treatment. However, knowledge of the possible association between allergy and need for fertility treatment is limited. Our aim was to explore a possible difference in having had fertility treatment in women with asthma and live births in those with perennial allergy (animals, fungi and dust mites) compared to no allergy/seasonal allergy. The primary outcome of interest was fertility treatment.

Patients and Methods

Women enrolled in the Management of Asthma during Pregnancy (MAP) program at Hvidovre Hospital, DK, were included in the present analysis provided they fulfilled the following criteria: 1) diagnosed with asthma and current anti-asthma therapy and 2) first visit to the respiratory outpatient clinic within the first 18 weeks of pregnancy. Participants were divided into two groups: asthma with perennial allergy (cases) and asthma with seasonal/no allergy (controls). Logistic regression analysis was applied, and findings expressed as odds ratios (OR).

Results

Among women with asthma and perennial allergy (n=544 cases), 13.8% (n=75) had fertility treatment, compared to only 10.1% (n=39) among women with asthma and seasonal/no allergy (n=388, controls) (OR 1.43, 95% CI 0.95–2.16, p=0.087). This association remained statistically insignificant after adjusting for confounders, including BMI (OR 1.19, 95% CI 0.77–1.84, p=0.433). In women ≥35 years of age, 28% (n=44) and 20% (n=19), respectively, among cases and controls had fertility treatment (OR 1.60, 95% CI 0.87–2.94, p=0.132), and likewise, statistically insignificant after adjusting for confounders (OR 1.41, 95% CI 0.74–2.69, p<0.293).

Conclusion

In women with asthma and live births, our study revealed a trend towards an association between perennial allergy and a higher need for fertility treatment compared to seasonal/no allergy.

Transcriptomic changes and potential regulatory mechanism of intrauterine human chorionic gonadotropin co-cultured with peripheral blood mononuclear cells infusion in mice with embryonic implantation dysfunction

Background

This study aimed to explore whether intrauterine infusion of peripheral blood mononuclear cells (PBMCs) could induce favorable transcriptomic changes in the endometrium for embryo implantation and the potential mechanism.

Methods

Twenty-one mice were randomly divided to five groups, including a normal pregnancy (NP) group, an embryo implantation dysfunction (EID) group, an EID with human chorionic gonadotropin (hCG) group, an EID with PBMCs group, and an EID with hCG co-cultured with PBMCs group. The endometrium in the implantation window from mice were collected and determined by RNA sequencing (RNA-Seq), and the expression of significantly different genes with high degree of coincidence was recommended and validated by quantitative real-time polymerase chain reaction (qRT-PCR).

Results

There were totally 1,366 up-regulated and 1,374 down-regulated genes in the EID mice compared with the normal pregnant mice. We selected (fold change ≥2, P<0.05) and verified the candidate genes associated with embryo implantation, immune response and other reproductive processes in previous reports by qRT-PCR. Leukemia inhibitory factor (LIF), solute carrier family 15 member 2 (SLC15A2), retinoic acid receptor responder 1 (RARRES1), vascular cell adhesion molecule 1 (VCAM1) were down-regulated and musculin (MSC), chemokine (C-X-C motif) ligand 14 (CXCL14) were up-regulated significantly in EID group (P<0.05), and the synergistic effects of hCG were seen. In addition, the expression of glucocorticoid receptor (GR)-β in PBMCs of NP mice was higher than that of EID mice, and up-regulated GR-β in EID mice could significantly increase the expression of LIF, SLC15A2, RARRES1 and VCAM1, and decrease the expression of CXCL14 and MSC, which indicated GR-β might be a transcriptional factor of the six genes above.

Conclusions

Intrauterine PBMCs perfusion might improve the performance of impaired endometrial receptivity by regulating LIF, SLC15A2, RARRES1, VCAM1, MSC as well as CXCL14, and hCG could enhance the effect of PBMCs. In addition, GR-β, as a transcriptional factor, could regulate the six genes in PBMCs.

Promoting Roles of Embryonic Signals in Embryo Implantation and Placentation in Cooperation with Endocrine and Immune Systems

Embryo implantation in the uterus is an essential process for successful pregnancy in mammals. In general, the endocrine system induces sufficient embryo receptivity in the endometrium, where adhesion-promoting molecules increase and adhesion-inhibitory molecules decrease. Although the precise mechanisms remain unknown, it is widely accepted that maternal–embryo communications, including embryonic signals, improve the receptive ability of the sex steroid hormone-primed endometrium. The embryo may utilize repulsive forces produced by an Eph–ephrin system for its timely attachment to and subsequent invasion through the endometrial epithelial layer. Importantly, the embryonic signals are considered to act on maternal immune cells to induce immune tolerance. They also elicit local inflammation that promotes endometrial differentiation and maternal tissue remodeling during embryo implantation and placentation. Additional clarification of the immune control mechanisms by embryonic signals, such as human chorionic gonadotropin, pre-implantation factor, zona pellucida degradation products, and laeverin, will aid in the further development of immunotherapy to minimize implantation failure in the future.

Spatio-temporal distribution of eosinophils in the mouse uterus during peri-implantation period

Embryo implantation is an immunologically paradoxical event. In humans and rodents, blastocysts adhere to uterine epithelium and then invade into endometrial stroma, while maternal body is protected from extraneous materials by its immune system. Eosinophils, a kind of leucocytes involving parasitic infections and allergic response, increase in number in uterus when serum estrogen level is elevated during estrus cycles. However, response of uterine eosinophils to ovarian estrogen during peri-implantation period is not clear. Therefore, we investigated the distribution of eosinophils in murine peri-implantation uterus. On day 0.5 of pregnancy, eosinophils were found primarily in endometrial stroma near the luminal epithelium, whereas they were primarily distributed in basal endometrium and myometrium on day 3.5 of pregnancy. The number of uterine eosinophils on day 4.5 of pregnancy was significantly increased by inhibition of maternal estrogen action. Collectively, our results indicate that the ovarian estrogen negatively regulates uterine eosinophil distribution during peri-implantation period and provide insight into a role of maternal immune system in embryo implantation.

Cytochrome c injection induced embryo loss

Cytochrome c has been used as first-aid in the clinic for organs which are lacking oxygen. But recent report show cytochrome c injection destroys dendritic cells (DCs) which play a pivotal role in feto-maternal tolerance. However, it is not clear whether cytochrome c injection causes abortion. The cytochrome c was injected by tail vein of mice at the Day 5.5 of pregnancy (E5.5) after mating with male BALB/c mice. The total number of implantations and resorption sites was recorded at the E12.5 in pregnant mice. Expression of interferon-γ, tumor necrosis-α interleukin (IL)-4, IL-10, IL-12 and transforming growth factor-β in the mouse endometrium was measured by ELISA. Injection of cytochrome c via tail vein at the E5.5 induced fetal resorption at E12.5, and evoked an immune imbalance at the maternal-fetal interface. Notably, injection of mouse bone marrow-derived DCs (BM-DCs) rescued the cytochrome c-evoked embryo resorption. The present study suggests cytochrome c injection causes embryo resorption in mice, hinting caution regarding the use of cytochrome c in pregnant women. In addition, it may provide an easy and novel way to establish a mouse model of abortion.HighlightsCytochrome c injection induced fetal rejection.Cytochrome c injection leads to a T helper 1/T helper 2 imbalance at the maternal-fetal interface.A mouse model of abortion was established by injecting tail vein with cytochrome c.

Fertility treatment among women with asthma: a case-control study of 3689 women with live births

Asthma has been linked with prolonged time to pregnancy. Our aim was to explore a possible association between asthma and need for fertility treatment among women with live births.All women enrolled in the Management of Asthma during Pregnancy (MAP) programme at Hvidovre Hospital, Denmark were each matched with the next three consecutive women giving birth at Hvidovre Hospital. Information from the Danish National Assisted Reproductive Technology (ART) registry was cross-linked with the Danish Medical Birth registry to identify live births. The primary outcome of interest was births following fertility treatment.Our sample comprised pregnancies from asthmatic mothers (n=932, described as "cases") and non-asthmatic mothers (n=2757, described as "controls"), with 12% (n=114) and 8% (n=212), respectively, having had fertility treatment (OR 1.67, 95% CI 1.32-2.13; p<0.001). This association remained statistically significant after adjusting for confounders, including body mass index (OR 1.31, 95% CI 1.00-1.70; p=0.047). In women ≥35 years, 25% of cases (n=63) and 13% of controls (n=82) received fertility treatment (OR 2.12, 95% CI 1.47-3.07; p<0.001), which also remained statistically significant after adjusting for confounders (OR 1.65, 95% CI 1.11-2.46; p=0.013).A higher proportion of the births from asthmatic mothers involved fertility treatment compared to non-asthmatic mothers, not least among women aged ≥35 years.

Potential Marker Pathways in the Endometrium That May Cause Recurrent Implantation Failure

The aim of this prospective cohort study was to identify altered biologic processes in the endometrium that may be potential markers of receptive endometrium in patients with repeated implantation failure (RIF) as compared with fertile controls. The study was conducted in a university-affiliated in vitro fertilization (IVF) gynecology clinic and molecular biology and genetics laboratory. Healthy fertile controls (n = 24) and patients with RIF (n = 24) were recruited. Window of implantation gene profiling associated with RIF was performed. Six hundred forty-one differentially expressed genes were identified, and 44 pathways were found enriched. Upon clustering of the enriched pathways, 9 representative pathways were established. The important pathways that were identified included circadian rhythm, pathways in cancer, proteasome, complement and coagulation cascades, citrate cycle, adherens junction, immune system and inflammation, cell cycle, and renin-angiotensin system. The involvement of the circadian rhythm pathway and other related pathways may alter the endometrium's functioning to ultimately cause RIF. Furthermore, we found that the pathogenesis of RIF was multifaceted and that numerous processes were involved. We believe that a better understanding of the underlying mechanisms of RIF will ultimately give rise to better treatment opportunities and to better outcomes in IVF.

Placental exosome-mediated Bta-miR-499-Lin28B/let-7 axis regulates inflammatory bias during early pregnancy

Abnormal inflammatory bias in the maternal-fetal interface leads to reproductive failure in mammals. Placental exosomes are involved in maternal-fetal communication during pregnancy. However, whether the placenta or fetus is involved in regulating the balance of uterine local inflammation through exosomes remains unclear, and the mechanism must be further explored. Here we demonstrated that placenta-specific exosomes are abundant in the peripheral blood of dairy cows during early pregnancy and selectively load miRNAs, such as bta-miR-499. In vitro, placental exosome-derived bta-miR-499 inhibits the activation of NF-κB via the Lin28B/let-7 axis, thus repressing LPS-induced inflammation in bovine endometrial epithelial (BEND) cells. Subsequently, inhibition of mmu-miR-499 leads to an impaired balance of inflammation at the maternal-fetal interface in vivo, resulting in an increased risk of pregnancy failure due to placental loss and fetal growth restriction. Thus, our data demonstrate that placental exosomal miR-499 may be a critical immune regulator in the regulation of the inflammation balance at the maternal-fetal interface in the early gestation of dairy cows and other mammals.

Improvement of implantation potential in mouse blastocysts derived from IVF by combined treatment with prolactin, epidermal growth factor and 4-hydroxyestradiol

STUDY QUESTION

Can supplementation of medium with prolactin (PRL), epidermal growth factor (EGF) and 4-hydroxyestradiol (4-OH-E2) prior to embryo transfer improve implantation potential in mouse blastocysts derived from IVF?

SUMMARY ANSWER

Combined treatment with PRL, EGF and 4-OH-E2 improves mouse blastocyst implantation rates, while alone, each factor is ineffective.

WHAT IS KNOWN ALREADY

Blastocyst dormancy during delayed implantation caused by ovariectomy is maintained by continued progesterone treatment in mice, and estrogen injection rapidly activates blastocysts to implantation-induced status in vivo. While the expression of many proteins is upregulated in implantation-induced blastocysts, selective proteolysis by proteasomes, such as estrogen receptor α (ESR1), occurs in implantation-induced blastocysts to achieve implantation-competent status. It is worth evaluating the proteins expressed during these periods to identify humoral factors that might improve the implantation potential of IVF-derived blastocysts because the poor quality of embryos obtained by IVF is one of the major causes of implantation failure.

STUDY DESIGN, SIZE, DURATION

Superovulated oocytes from ICR mice were fertilized with spermatozoa and then cultured in vitro in potassium simplex optimized medium (KSOM) without phenol red (KSOM-P) for 90-96 h. Blastocysts were treated with PRL (10 or 20 mIU/mL), EGF (5 or 10 ng/mL) or 4-OH-E2 (1 or 10 nM) in KSOM-P for 24 h.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Levels of breast cancer 1 (BRCA1), EGF receptor (EGFR, also known as ERBB1), ERBB4, tubulointerstitial nephritis antigen-like 1 (TINAGL1) and ESR1 protein were examined with immunohistochemical analysis using immunofluorescence methods and confocal laser scanning microscopy. For embryo transfer, six blastocysts were suspended in HEPES-buffered KSOM-P medium and transferred into the uteri of recipient mice on the morning of Day 4 (0900-1000 h) of pseudopregnancy (Day 1 = vaginal plug). The number of implantation sites was then recorded on Day 6 using the blue dye method.

MAIN RESULTS AND THE ROLE OF CHANCE

PRL, EGF and 4-OH-E2 each promoted BRCA1 protein level in the trophectoderm (TE). While PRL treatment resulted in an increase in EGFR, EGF increased both EGFR and ERBB4 in the blastocyst TE. TINAGL1 in the TE was enhanced by 4-OH-E2, which also increased localization of this protein to the basement membrane. Treatment with PRL, EGF or 4-OH-E2 alone did not improve blastocyst implantation rates. Combined treatment with PRL, EGF and 4-OH-E2 resulted in increased levels of EGFR, ERBB4, TINAGL1 and BRCA1 in the TE, whereas ESR1 was not upregulated in the treated blastocysts. Furthermore, combined treatment with PRL, EGF and 4-OH-E2 improved blastocyst implantation rates versus control (P = 0.009).

LARGE SCALE DATA

Not applicable.

LIMITATIONS, REASONS FOR CAUTION

Our studies were carried out in a mouse model, and the conclusions were drawn from limited results obtained from one species. Whether the increase in EGFR, ERBB4 and TINAGL1 protein in the TE improves implantation potential of blastocysts needs to be further studied experimentally by assessing other expressed proteins. The influence of combined supplementation in vitro of PRL, EGF and 4-OH-E2 on implantation also requires further examination and optimization in human blastocysts before it can be considered for clinical use in ART.

WIDER IMPLICATIONS OF THE FINDINGS

Enhanced implantation potential by combined treatment with PRL, EGF and 4-OH-E2 appears to result in the upregulation of at least two distinct mechanisms, namely signaling via EGF receptors and basement membrane formation during the peri-implantation period in mice. While PRL, EGF and 4-OH-E2 each promoted BRCA1 protein level in the TE, treatment with each alone did not improve blastocyst implantation. Therefore, BRCA1 protein appears to be unnecessary for the attachment reaction in blastocysts in mice Combined supplementation of PRL, EGF and 4-OH-E2 might also be of relevance for embryo transfer of human IVF-derived blastocysts for ART.

STUDY FUNDING/COMPETING INTEREST(S)

This work was supported in part by the JSPS KAKENHI [Grant numbers 22580316 and 25450390 (to H.M.)] and the Joint Research Project of Japan-U.S. Cooperative Science Program (to H.M.). The authors have no conflict of interest to declare.

Sorcin is involved during embryo implantation via activating VEGF/PI3K/Akt pathway in mice

Our earlier studies have demonstrated the cyclic variation and also the altered expression of sorcin in endometrium during early-to-mid-secretory phase transition in women with unexplained infertility. The current study was undertaken to establish the functional role of sorcin in endometrial receptivity in mice. Results indicated that sorcin was highly expressed during the window of implantation in mice and functional blockage of sorcin caused significant reduction in number of implanted blastocyst. The receptivity markers (i.e.Integrin β3, HBEGF, IGFBP1, WNT4 and Cyclin E)) were found to be downregulated in sorcin knocked down uterine horn on day 5 as compared to untreated horn. The reduced attachment and expansion of BeWo spheroids on RL95-2 endometrial cells with sorcin knock down, in in vitro model of endometrium-trophoblast interaction further supported these findings. Uterine sorcin expression pattern during estrous cycle and in delayed implantation mice model suggested the upregulation of sorcin by estrogen. The functional blockade of sorcin induced the intracellular Ca⁺² levels in endometrial epithelial cells (EECs), which indicated that altered Ca⁺² homeostasis might be responsible for implantation failure. Sorcin silencing led to significant reduction in the expression of angiogenic factor VEGF and its downstream effector molecules i.e. PI3K, Akt and NOS. The migratory and invasive properties of HUVECs were abrogated by anti-VEGF or by adding culture media from sorcin blocked EECs, which indicated that sorcin might mediate angiogenesis during implantation. Taken together, sorcin is involved in the regulation of Ca⁺²-mediated angiogenesis via VEGF/PI3K/Akt pathway in endometrial cells and plays a crucial role in preparing the endometrium for implantation.

Expression and localization of polypeptide N-acetylgalactosaminyltransferase-like protein 5 in the reproductive organs and sperm of Hu sheep

The polypeptide N-acetylgalactosaminyltransferase-like protein 5 (GALNTL5) is involved in male fertility; however, its involvement in the reproduction and fertility of females remains unclear. Therefore, the present study aimed to examine the presence of GALNTL5 in the reproductive organs of ewes during the estrus period and to investigate its expression in cauda epididymal and ejaculated sperm. Results showed that GALNTL5 mRNA and protein were present in some reproductive organs of ewes during the estrus period. The highest levels of GALNTL5 mRNA and protein occurred in the uterine horn and oviductal ampulla and the lowest in the uterine cervix and oviductal infundibulum. Immunohistochemical analysis revealed that GALNTL5 protein was mainly located in luminal and glandular epithelial cells of the uterus and oviduct, and in the theca and granulosa cells of the ovary. GALNTL5 gene expression was significantly higher in ejaculated sperm than in cauda epididymal sperm. The amount of GALNTL5 protein in seminal plasma was significantly higher than in ejaculated sperm. Additionally, GALNTL5 was strongly localized in the mid-piece and head of ejaculated sperm, and in the head-tail coupling apparatus and acrosome of cauda epididymal sperm. This is the first evidence that GALNTL5 might play an important role in a range of reproductive functions as well as in sperm motility and capacitation. Further studies are required to evaluate the function of GALNTL5 in reproduction.

Molecular and cellular events during blastocyst implantation in the receptive uterus: clues from mouse models

The success of implantation is an interactive process between the blastocyst and the uterus. Synchronized development of embryos with uterine differentiation to a receptive state is necessary to complete pregnancy. The period of uterine receptivity for implantation is limited and referred to as the “implantation window”, which is regulated by ovarian steroid hormones. Implantation process is complicated due to the many signaling molecules in the hierarchical mechanisms with the embryo-uterine dialogue. The mouse is widely used in animal research, and is uniquely suited for reproductive studies, i.e., having a large litter size and brief estrous cycles. This review first describes why the mouse is the preferred model for implantation studies, focusing on uterine morphology and physiological traits, and then highlights the knowledge on uterine receptivity and the hormonal regulation of blastocyst implantation in mice. Our recent study revealed that selective proteolysis in the activated blastocyst is associated with the completion of blastocyst implantation after embryo transfer. Furthermore, in the context of blastocyst implantation in the mouse, this review discusses the window of uterine receptivity, hormonal regulation, uterine vascular permeability and angiogenesis, the delayed-implantation mouse model, morphogens, adhesion molecules, crosslinker proteins, extracellular matrix, and matricellular proteins. A better understanding of uterine and blastocyst biology during the peri-implantation period should facilitate further development of reproductive technology.

Serum Cytokine Levels are related to Nesfatin-1/NUCB2 Expression in the Implantation Sites of Spontaneous Abortion Model of CBA/j × DBA/2 Mice

The process of spontaneous abortion involves a complex mechanism with various cytokines, growth factors, and hormones during the pregnancy. However, the mechanism underlying spontaneous abortion by pro- and anti-inflammatory cytokines in the serum during the pregnancy is not fully understood. Therefore, the purpose of this study was to examine the relationship between the serum levels of pro- and anti-inflammatory cytokines and spontaneous abortion using the CBA/j × DBA/2 mouse model. Serum levels of pro-inflammatory cytokines, such as IFN-γ, IL-1α and TNF-α were not increased in abortion model mice, but anti-inflammatory cytokines, such as IL-4, IL-13 and IL-1ra were decreased compared to normal pregnant mice. In addition, serum levels of chemokine, such as SDF-1, G-CSF, M-CSF, IL-16, KC and MCP-1 were decreased in abortion model mice compared to normal pregnant mice. However, the expression levels of nesfatin-1/NUCB2 mRNA and protein in the uteri of implantation sites were significantly higher in abortion model mice than normal pregnant mice. These results suggest that uterine nesfatin-1/NUCB2 expression may be down-regulated by inflammatory cytokines and chemokines in the serum of pregnant mice. Moreover, this study suggests the possibility that nesfatin-1/NUCB2 expressed in the implantation sites may be associated with the maintenance of pregnancy.

Estrous Cycle and Gestational Age-Dependent Expression of Members of the Interleukin-36 Subfamily in a Semi-Allogeneic Model of Infected and Non-Infected Murine Pregnancy

The IL-36 subfamily is a recently described group of cytokines with pro-inflammatory behavior, comprising three agonists (α, β, and γ), its receptor (R), and one antagonist (Ra). The expression and function of IL-36 subfamily members in the estrous cycle in healthy and infected pregnancy has not been described. We evaluated mRNA and protein expression of IL-36 family members during the estrous cycle, implantation, fetal development, and post-labor periods in a model of allogenic pregnancy in mice. We also explored the ability of Listeria monocytogenes to modulate the expression of IL-36 subfamily members during pregnancy. Expression of IL-36 subfamily members showed different expression during the estrous cycle and pregnancy but was induced at estrous, 16.5 days post coitum (dpc), 18.5 dpc, and labor. IL-36 subfamily members showed a characteristic distribution in the glandular epithelium, perimetrium, myometrium, and stratum vasculare. Infection with L. monocytogenes during pregnancy induced strong production of IL-36 subfamily members, an observation that correlated with an increasing prevalence of fetal loss. In conclusion, IL-36 agonists showed specific patterns of mRNA and protein expression that might suggest functional specialization or specific target cells. Infection with L. monocytogenes during pregnancy induced strong production of IL-36 subfamily members.

Seminal Fluid-Mediated Inflammation in Physiology and Pathology of the Female Reproductive Tract

Inflammation is a multifaceted process involving a host of resident and recruited immune cells that eliminate the insult or injury and initiate tissue repair. In the female reproductive tract (FMRT), inflammation-mediated alterations in epithelial, vascular, and immune functions are important components of complex physiological processes and many local and systemic pathologies. It is well established that intracoital and postcoital function of seminal fluid (SF) goes beyond nutritive support for the spermatozoa cells. SF, in particular, the inflammatory bioactive lipids, and prostaglandins present in vast quantities in SF, have a role in localized immune modulation and regulation of pathways that can exacerbate inflammation in the FMRT. In sexually active women SF-mediated inflammation has been implicated in physiologic processes such as ovulation, implantation, and parturition while also enhancing tumorigenesis and susceptibility to infection. This review highlights the molecular mechanism by which SF regulates inflammatory pathways in the FMRT and how alterations in these pathways contribute to physiology and pathology of the female reproductive function. In addition, based on findings from TaqMan® 96-Well Plate Arrays, on neoplastic cervical cells treated with SF, we discuss new findings on the role of SF as a potent driver of inflammatory and tumorigenic pathways in the cervix.

Impaired female fertility in tubulointerstitial antigen-like 1-deficient mice

Tubulointerstitial nephritis antigen-like 1 (Tinagl1, also known as adrenocortical zonation factor 1 [AZ-1] or lipocalin 7) is a matricellular protein. Previously, we demonstrated that Tinagl1 expression was restricted to extraembryonic regions during the postimplantation period and detected marked expression in mouse Reichert's membranes. In uteri, Tinagl1 is markedly expressed in the decidual endometrium during the postimplantation period, suggesting that it plays a physical and physiological role in embryo development and/or decidualization of the uterine endometrium during pregnancy. In the present study, in order to determine the role of Tinagl1 during embryonic development and pregnancy, we generated Tinagl1-deficient mice. Although Tinagl1(-/-) embryos were not lethal during development to term, homologous matings of Tinagl1(-/-) females and Tinagl1(-/-) males showed impaired fertility during pregnancy, including failure to carry pregnancy to term and perinatal lethality. To examine ovarian function, ovulation was induced with equine chorionic gonadotropin (eCG) and human chorionic gonadotropin (hCG); the number of ovulated oocytes did not differ between Tinagl1(-/-) and Tinagl1(flox/flox). In vitro fertilization followed by embryo culture also demonstrated the normal developmental potential of Tinagl1-null embryos during the preimplantation period. Our results demonstrate that Tinagl1 deficiency affects female mice and results in subfertility phenotypes, and they suggest that although the potential of Tinagl1(-/-) oocytes is normal, Tinagl1 is related to fertility in adult females but is not essential for either fertilization or preimplantation development in vitro.

Divergent endometrial inflammatory cytokine expression at peri-implantation period and after the stimulation by copper intrauterine device

Endometrial inflammation has contradictory effects. The one occurring at peri-implantation period is favourable for embryo implantation, whereas the other occurring after the stimulation by copper intrauterine device (Cu-IUD) prevents from embryo implantation. In this study, 8 week female ICR mice were used to investigate the endometrial inflammation, in which they were at proestrus stage (Group 1), at peri-implantation period (Group 2), and had a copper wire implanted into right uterine horn (Group 3). Cytokine array revealed that two cytokines were highly expressed in Group 2 and Group 3 as compared with Group 1, and seven cytokines, including tumour necrosis factor α (TNF-α), had selectively strong expression in Group 3. Immunohistochemistry demonstrated prominent TNF-α staining on the endometrium after Cu-IUD stimulation, and in vitro culture of human endometrial glandular cells with Cu induced TNF-α secretion. The increased TNF-α concentration enhanced in vitro THP-1 cells chemotaxis, and reduced embryo implantation rates. These results suggest that inflammatory cytokine profiles of endometrium are different between those at peri-implantation period and after Cu-IUD stimulation, and TNF-α is the one with selectively strong expression in the latter. It might account for the contradictory biological effects of endometrial inflammation.

Characterization of the Transcriptional Complexity of the Receptive and Pre-receptive Endometria of Dairy Goats

Endometrium receptivity is essential for successful embryo implantation in mammals. However, the lack of genetic information remains an obstacle to understanding the mechanisms underlying the development of a receptive endometrium from the pre-receptive phase in dairy goats. In this study, more than 4 billion high-quality reads were generated and de novo assembled into 102,441 unigenes; these unigenes were annotated using published databases. A total of 3,255 unigenes that were differentially expressed (DEGs) between the PE and RE were discovered in this study (P-values < 0.05). In addition, 76,729–77,102 putative SNPs and 12,837 SSRs were discovered in this study. Bioinformatics analysis of the DEGs revealed a number of biological processes and pathways that are potentially involved in the establishment of the RE, notably including the GO terms proteolysis, apoptosis, and cell adhesion and the KEGG pathways Cell cycle and extracellular matrix (ECM)-receptor interaction. We speculated that ADCY8, VCAN, SPOCK1, THBS1, and THBS2 may play important roles in the development of endometrial receptivity. The de novo assembly provided a good starting point and will serve as a valuable resource for further investigations into endometrium receptivity in dairy goats and future studies on the genomes of goats and other related mammals.

HCG-Activated Human Peripheral Blood Mononuclear Cells (PBMC) Promote Trophoblast Cell Invasion

Successful embryo implantation and placentation depend on appropriate trophoblast invasion into the maternal endometrial stroma. Human chorionic gonadotropin (hCG) is one of the earliest embryo-derived secreted signals in the peripheral blood mononuclear cells (PBMC) that abundantly expresses hCG receptors. The aims of this study were to estimate the effect of human embryo-secreted hCG on PBMC function and investigate the role and underlying mechanisms of activated PBMC in trophoblast invasion. Blood samples were collected from women undergoing benign gynecological surgery during the mid-secretory phase. PBMC were isolated and stimulated with or without hCG for 0 or 24 h. Interleukin-1β (IL-1β) and leukemia inhibitory factor (LIF) expressions in PBMC were detected by enzyme-linked immunosorbent assay and real-time polymerase chain reaction (PCR). The JAR cell line served as a model for trophoblast cells and was divided into four groups: control, hCG only, PBMC only, and PBMC with hCG. JAR cell invasive and proliferative abilities were detected by trans-well and CCK8 assays and matrix metalloproteinase (MMP)-2 (MMP-2), MMP-9, vascular endothelial growth factor (VEGF), tissue inhibitor of metalloproteinase (TIMP)-1, and TIMP-2 expressions in JAR cells were detected by western blotting and real-time PCR analysis. We found that hCG can remarkably promote IL-1β and LIF promotion in PBMC after 24-h culture. PBMC activated by hCG significantly increased the number of invasive JAR cells in an invasion assay without affecting proliferation, and hCG-activated PBMC significantly increased MMP-2, MMP-9, and VEGF and decreased TIMP-1 and TIMP-2 expressions in JAR cells in a dose-dependent manner. This study demonstrated that hCG stimulates cytokine secretion in human PBMC and could stimulate trophoblast invasion.

Changes in Functional Activity of JEG-3 Trophoblast Cell Line in the Presence of Factors Secreted by Placenta

BACKGROUND AND AIMS

Cells in the maternal-fetal interface secrete cytokines that regulate proliferation, migration, and trophoblast invasion during the first trimester of pregnancy and the limitation of these processes during the third trimester. The aim of the study was to evaluate the influence of factors secreted by human placenta during the first and third trimester of pregnancy on cytokine receptor expression and proliferative and migratory activity of JEG-3 trophoblast cells.

METHODS

The research was conducted using the explant conditioned media of placentas obtained from healthy women with elective termination of pregnancy at 9-11 weeks and placentas of women whose pregnancy progressed without complications at 38-39 weeks. Assessment of surface molecule expression was performed using FACS Canto II flow cytometer (BD, USA). The proliferative activity of JEG-3 trophoblast cells was evaluated by dyeing with crystal violet vital dye. The migration activity of JEG-3 was evaluated using 24-well insert plates with polycarbonate inserts (pore size 8 microns).

RESULTS

Expression of CD116, CD118, CD119, IFNγ-R2, CD120b, CD183, CD192, CD295, EGFR, and TGFβ-R2 on JEG-3 was higher when the cells were incubated in the presence of the third trimester placental factors in comparison with the first trimester placental factors. Factors secreted by the placenta during the third trimester of pregnancy had more pronounced stimulatory effect on the proliferation and migration of trophoblast in comparison with baseline levels and with the effect of the first trimester placental factors.

CONCLUSIONS

The findings suggest that the behavior of trophoblasts in vitro might not be representative of in vivo behavior in the absence of additional local factors that influence the trophoblast in vivo.

Transcriptome of early embryonic invasion at implantation sites in a murine model

Successful implantation relies on the interaction between a competent embryo and a receptive endometrium. The aim of the present study was to investigate genes differentially expressed in early invasive embryonic tissue versus decidual tissue in mice. Samples were obtained from the ectoplacental cone, the immediately surrounding deciduas and from deciduas from interimplantation sites. Microarray analysis showed that 817 genes were differentially expressed between extra-embryonic tissue and the surrounding decidua and that 360 genes were differentially expressed between the different deciduas, with a high representation of developmental processes. Genes differentially expressed in the maternal compartment included chemokines, lipoproteins, growth factors and transcription factors, whereas the embryonic invasive tissue expressed genes commonly observed in invasive tumour-like processes. These results provide information about genes involved in early embryonic invasion and the control exerted by the surrounding decidua. This information may be useful to find targets involved in pathologies associated with implantation failure and early pregnancy loss.

Ion/Water Channels for Embryo Implantation Barrier

Successful implantation involves three distinct processes, namely the embryo apposition, attachment, and penetration through the luminal epithelium of the endometrium to establish a vascular link to the mother. After penetration, stromal cells underlying the epithelium differentiate and surround the embryo to form the embryo implantation barrier, which blocks the passage of harmful substances to the embryo. Many ion/water channel proteins were found to be involved in the process of embryo implantation. First, ion/water channel proteins play their classical role in establishing a resting membrane potential, shaping action potentials and other electrical signals by gating the flow of ions across the cell membrane. Second, most of ion/water channel proteins are regulated by steroid hormone (estrogen or progesterone), which may have important implications to the embryo implantation. Last but not least, these proteins do not limit themselves as pure channels but also function as an initiator of a series of consequences once activated by their ligand/stimulator. Herein, we discuss these new insights in recent years about the contribution of ion/water channels to the embryo implantation barrier construction during early pregnancy.

Degradation of estrogen receptor α in activated blastocysts is associated with implantation in the delayed implantation mouse model

Implantation of a blastocyst into a receptive uterus involves a series of highly coordinated cellular and molecular events directed by ovarian estrogen and progesterone. In particular, estrogen is essential for on-time uterine receptivity and blastocyst activation in mice. Although estrogen receptor α (ERα) is expressed in blastocysts, its targeted disruption leaves embryonic development and implantation unaffected. Therefore, the role of ERα in implanting blastocysts remains unclear. Using a delayed implantation model in mice, we showed increased expression of ERα in implantation-induced (activated) blastocysts; however, this ERα expression in activated blastocysts decreased within 6-h culture. In contrast, breast cancer 1 (Brca1) was maintained in the blastocysts during the culture. The treatment of activated blastocysts with the proteasome inhibitor MG132 demonstrated that proteolysis is associated with down-regulation of ERα expression in activated blastocysts. Embryo transfer of MG132-treated activated blastocysts into recipient mice on the morning of Day 4 of pseudopregnancy (Day 1 = vaginal plug) showed a decreased implantation rate, whereas combined treatment with MG132 and the ER antagonist, ICI 182,780, resulted in recovery of the rate of implantation. This study has revealed that down-regulation of ERα in activated blastocyst is associated with completion of blastocyst implantation after embryo transfer on the morning of Day 4 of pseudopregnancy. Our results also suggest that selective protein turnover, such as that of ERα, occurs in activated blastocysts, while expression of other proteins, including Brca1, is maintained at the same stage.

Expression and localization of Luman RNA and protein during mouse implantation and decidualization

Luman (also known as LZIP and CREB3) is a basic leucine zipper transcription factor of the cAMP response element-binding protein/activating transcription factor gene family. Although Luman had specific roles near termination of Drosophila embryogenesis, the physiological functions of Luman in female mammals have apparently not been reported. Therefore, our objective was to investigate the spatiotemporal expression and regulation of Luman in the mouse uterus during the peri-implantation period. Luman protein was clearly present in the luminal and glandular epithelium on days 1 to 4 of pregnancy (day 1, presence of a vaginal plug) and was observed in decidual cells on day 6 of pregnancy. Expression had progressively increased to day 7 when the second decidual zone was formed. On day 8, apoptosis of the decidualized cells was present, and Luman protein expression was decreased (in close association with decidualization). Luman protein was also present in decidual cells of the artificially decidualized uterus. The expression of Luman was regulated by an activated embryo (according to its expression patterns during pseudopregnancy and delayed implantation). Furthermore, expression of Luman was induced by estrogen in ovariectomized mice. We have concluded that Luman might have important roles in embryo implantation and decidualization.

Human milk: a source of more life than we imagine

The presence of bacteria in human milk has been acknowledged since the seventies. For a long time, microbiological analysis of human milk was only performed in case of infections and therefore the presence of non-pathogenic bacteria was yet unknown. During the last decades, the use of more sophisticated culture-dependent and -independent techniques, and the steady development of the -omic approaches are opening up the new concept of the ‘milk microbiome’, a complex ecosystem with a greater diversity than previously anticipated. In this review, possible mechanisms by which bacteria can reach the mammary gland (contamination versus active migration) are discussed. In addition, the potential roles of human milk for both infant and maternal health are summarised. A better understanding of the link between the milk microbiome and health benefit, the potential factors influencing this relationship and whether or not it can be influenced by nutrition is required to open new avenues in the field of pregnancy and lactation.

Expression pattern implicates a potential role for luman recruitment factor in the process of implantation in uteri and development of preimplantation embryos in mice

Luman/CREB3 recruitment factor (LRF or CREBRF) was identified as a regulator of Luman (or CREB3) that is involved in the unfolded protein response during endoplasmic reticulum stress. Luman is implicated in a multitude of functions ranging from viral infection and immunity to cancer. The biological function of LRF, however, is unknown. In this paper, we report that uteri of pregnant mice and embryos displayed enhanced LRF expression at all stages, and the expressed LRF was found to be localized specifically at implantation sites. On the other hand, uteri of mice induced for delayed implantation or pseudopregnant mice showed low levels of LRF expression, suggesting that LRF mediates uterine receptivity during implantation. Further, expression of LRF was found to be modulated by steroid hormones such as progesterone and estradiol. This study thereby identifies a potential role for LRF in the process of implantation in uteri and development of preimplantation embryos in mice.

Modulation of the expression of the transcription factors T-bet and GATA-3 in immortalized human endometrial stromal cells (HESCs) by sex steroid hormones and cAMP

T-bet and GATA-3 are known to regulate cytokine expression in T lymphocytes, and cytokines have been implicated in endometrial regulation and implantation. Previous work showed that female steroid hormones modulate the expression of T-bet in endometrial epithelial cells, suggesting a mechanism for local immune regulation in the human endometrium. We hypothesized that stromal cells are involved in immune regulation, as they have been shown to exert paracrine effects on other endometrial cells and compartments and also secrete cytokines. The objective of this study was to examine the modulation of the gene expression of T-bet and GATA-3, and of the cytokines interferon γ (IFN-γ) and interleukin 4 (IL-4), by female steroid hormones, in human endometrial stromal cells (HESC) in long-term cultures (30 days) mimicking the normal menstrual cycle. T-bet and GATA-3 messenger RNA (mRNA) expression was detected by real-time polymerase chain reaction, and intracellular protein production was demonstrated by immunoblotting. In addition, secretion of IL-4 and IL-15 was measured by enzyme-linked immunosorbent assay. T-bet and IL-4 mRNA expression increased and GATA-3 decreased under decidualization conditions; IFN-γ was not detected. Secretion of IL-15 increased during decidualization, and IL-15 upregulated T-bet gene expression. In conclusion, gene expression of T-bet and GATA-3 by endometrial stromal cells is under hormonal conditions mimicking decidualization, and the results are consistent with an autocrine regulatory mechanism of IL-15 secretion and T-bet expression.

The paracrinology of tubal ectopic pregnancy

As part of successful human reproduction, the Fallopian tube must provide a suitable environment for pre-implantation development of the embryo and for efficient transport of the embryo to the uterus for implantation. These functions are coordinated by paracrine interactions between tubal epithelial, smooth muscle and immune cells and the cells of the developing embryo. Alterations in these signals can lead to a tubal microenvironment encouraging of embryo implantation and to dysregulated tubal motility, ultimately resulting in inappropriate and early implantation of the embryo in the Fallopian tube. Here, we highlight novel and emerging concepts in tubal physiology and pathobiology, such as the induction of a receptive phenotype within the Fallopian tube, leading to ectopic implantation. Chlamydia trachomatis infection is a risk factor for tubal ectopic pregnancy. Activation of toll-like receptor 2 (TLR-2) in the Fallopian tube epithelium, by C. trachomatis has recently been demonstrated, leading to the dysregulation of factors involved in implantation and smooth muscle contractility, such as prokineticins (PROK), activin A and interleukin 1 (IL-1). The Fallopian tube has also recently been shown to harbour a unique population of immune cells, compared to the endometrium. In addition, the complement of immune cells in the Fallopian tube has been reported to be altered in Fallopian tube from women with ectopic pregnancy. There are increasing data suggesting that vascularisation of the Fallopian tube, by the embryo during ectopic pregnancy, differs from that initiated in the uterus during normal pregnancy. This too, is likely the result of paracrine signals between the embryo and the tubal microenvironment.

Intrauterine administration of autologous peripheral blood mononuclear cells increases clinical pregnancy rates in frozen/thawed embryo transfer cycles of patients with repeated implantation failure

Intrauterine administration of autologous peripheral blood mononuclear cells (PBMC) activated by HCG in vitro are reported to improve implantation rates in patients with repeated failure of IVF-ET. In this study, we examined the effects of intrauterine administration of freshly isolated PBMC on clinical pregnancy and the implantation rates of patients who received frozen/thawed embryo transfer by prospective cohort study. Patients who had not achieved a successful pregnancy despite at least one or more IVF-ET sessions were enrolled in this study (n = 253, 253 cycles). Based on the patient's treatment preferences, PBMC were freshly isolated from each patient and then administered to the intrauterine cavity of that patient. Frozen/thawed embryo transfer was performed and the success of implantation in the PBMC-treated group (n = 83, 83 cycles) was compared with that in the non-treated control groups (n = 170, 170 cycles). There were no significant differences in the clinical pregnancy rate (34.9% vs. 32.9%), implantation rate (21.6% vs. 21.1%) and live birth delivery rate (21.7% vs. 21.8%) between PBMC-treated and non-treated groups. However, when the analyses were restricted to patients who had three or more implantation failures, the clinical pregnancy rate and the implantation rate in the PBMC-treated group (42.1% and 25.0%, p<0.05; n = 19 and 32, respectively) were significantly higher than those in the non-treated group (16.7% and 9.4%, p<0.05; n = 36 and 64, respectively). These findings indicate that intrauterine administration of autologous PBMC freshly isolated from patients, effectively improves embryo implantation in patients with three or more IVF failures.

A novel model of human implantation: 3D endometrium-like culture system to study attachment of human trophoblast (Jar) cell spheroids

There is an urgent need to develop optimized experimental models to examine human implantation. These studies aimed to (i) establish a human endometrium-like three-dimensional (3D) culture system, and (ii) examine the attachment of trophoblast-like Jar spheroids to the culture. In the present work, 3D endometrial cultures were constructed with fibrin-agarose as matrix scaffold, and using epithelial and stromal cells from both human primary cultures and established cell lines. An attachment assay between trophoblast cells and the 3D culture was developed. Epithelial cells (cytokeratin(+)) concentrated on top of the matrix forming a monolayer, and stromal cells (vimentin(+)) resided within the matrix, resembling the normal endometrial structure. The capability of primary epithelial cells to form glands spontaneously was observed. Human trophoblast cells (Jar cells) were hCG(+) by immunostaining, allowed to form spheroids, and confirmed to secrete hCG into the medium. Time-dependent experiments demonstrated a high rate of attachment of Jar spheroids to the epithelium, and adhesion was strongly related to the various cell types present in the 3D culture. An architecturally and functionally competent 3D endometrial culture system was established, that coupled with Jar spheroids mimicking trophoblast cells, provides a unique in vitro model for the study of certain aspects of human implantation.

Antinuclear autoantibodies in women with recurrent pregnancy loss

PROBLEM

To investigate the possibility that antinuclear antibodies (ANA) are involved in recurrent pregnancy loss (RPL).

METHODS

Case-control study carried out on 294 women (194 cases and 100 controls) in two University hospitals. The presence, the serum titers and the indirect immunofluorescence (IIF) patterns of ANA were determined in women with RPL and in control women.

RESULTS

Antinuclear antibodies at titers ≥ 1:80 were detected in 97 (50%) women with RPL and in 16 (16%) control women. Elevated ANA titers (≥1:180) were detected only in RPL women, whereas all control women had ANA titers no greater than 1:80. No differences could be detected in the IIF patterns between RPL and control women. No differences in ANA positivity could be detected according to the type (primary or secondary) or number (>2 versus ≥3) of losses.

CONCLUSIONS

ANA could be of some value in identifying women with RPL with potential, although still not fully defined, immune abnormalities.

Tumor necrosis factor receptor subfamily 9 (Tnfrsf9) gene is expressed in distinct cell populations in mouse uterus and conceptus during implantation period of pregnancy

Tumor necrosis factor receptor subfamily 9 (TNFRSF9) plays a potentially important general role in immune function. Tnfrsf9 gene expression has previously been characterized in late pregnant mouse uterus and placenta. However, little is known about its expression in the uterus during the implantation phase of early pregnancy. We have assessed the levels and localization of Tnfrsf9 expression in the mouse uterus and conceptus during implantation. Relative Tnfrsf9 mRNA levels were significantly higher in implantation than in non-implantation site tissue on days 6.5-8.5 of pregnancy. This increase did not depend on the presence of the conceptus, as mRNA levels were not significantly different between pregnant implantation sites and artificially induced deciduomas. Localization by in situ hybridization revealed a subpopulation of endothelial and uterine natural killer cells expressing Tnfrsf9 in the endometrium during implantation. In the developing conceptus, primary trophoblast giant and ectoplacental cells expressed Tnfrsf9 on days 6.5-8.5, followed by expression in the trophoblast giant cell layers surrounding the conceptus on day 9.5 of pregnancy. Two main splice forms of Tnfrsf9 mRNA exist and encode proteins with distinct biological functions; both mRNA splice forms were present in uterine and conceptus tissues as determined by reverse transcription with the polymerase chain reaction. Thus, both membrane and soluble forms of Tnfrsf9 are expressed in specific cell types of the uterus and conceptus during the progression of implantation in mice and possibly have an important function in this process.