ZEB1 Promotes Epithelial-Mesenchymal Transition of Endometrial Epithelial Cells and Plays a Critical Role in Embryo Implantation in Mice.

Zinc finger E-box binding homeobox 1 (ZEB1) promotes epithelial-mesenchymal transition (EMT) in carcinogenesis, but its role in embryo implantation has not yet been well studied. In the present study we evaluated the hypothesis that ZEB1-induced EMT is essential for embryo implantation in vivo. Endometrial epithelium from female Kunming mice (non-pregnant, and pregnant from day 2.5 to 6.5) were collected for assessment of mRNA/protein expression of ZEB1, and EMT markers E-cadherin and vimentin, by employment of real-time quantitative reverse transcription PCR, Western blot, and immunohistochemical staining. To test if knockdown of ZEB1 affects embryo implantation in vivo, mice received intrauterine injection of shZEB1 before the number of embryos implanted was counted. The results showed that, ZEB1 was highly expressed at both mRNA and protein levels in the mouse endometrium on day 4.5 of pregnancy, paralleled with down-regulated E-cadherin and up-regulated vimentin expression (P < 0.05). Intrauterine injection of shZEB1 markedly suppressed embryo implantation in mice (P < 0.01). Conclusively, the present work demonstrated that ZEB1 is essential for embryo implantation under in vivo condition, and is possibly due to its effect on modulation of endometrial receptivity through EMT.

Monoamine oxidases activity maintains endometrial monoamine homeostasis and participates in embryo implantation and development.

BACKGROUND: Monoamine oxidases (MAOs) is an enzyme that catalyzes the deamination of monoamines. The current research on this enzyme is focused on its role in neuropsychiatric, neurodevelopmental, and neurodegenerative diseases. Indeed, MAOs with two isoforms, namely, A and B, are located on the outer mitochondrial membrane and are widely distributed in the central nervous system and peripheral tissues. Several reports have described periodic changes in the levels of this enzyme in the human endometrial tissue. RESULTS: The novel role of MAOs in endometrial receptivity establishment and embryonic development by maintaining monoamine homeostasis was investigated in this study. MAOs activity was observed to be enhanced during the first trimester in both humans and mice under normal conditions. However, under pathological conditions, MAOs activity was reduced and was linked to early pregnancy failure. During the secretory phase, the endometrial stromal cells differentiated into decidual cells with a stronger metabolism of monoamines by MAOs. Excessive monoamine levels cause monoamine imbalance in decidual cells, which results in the activation of the AKT signal, decreased FOXO1 expression, and decidual dysfunction. CONCLUSIONS: The findings suggest that endometrial receptivity depends on the maintenance of monoamine homeostasis via MAOs activity and that this enzyme participates in embryo implantation and development.

Association of Fibroblast Growth Factor-1 Promoter Polymorphism and its Serum Concentrations with Repeated Implantation Failure after In vitro Fertilisation: A Cross-sectional Study.

Background: Fibroblast growth factors (FGFs) play a key role in embryo implantation and support endometrial trophoblastic interaction. Aim: The aim of the study was to evaluate the association between FGF-1 (rs34011) gene variety and its serum concentration with repeated implantation failure (RIF). Setting and Design: The design of the study was a cross-sectional study. Materials and Methods: Four hundred infertile women with a history of RIF and 400 healthy women undergoing the first in vitro fertilisation-embryo transfer attempt with successful delivery (controls) were enrolled in the study. Genomic DNA was extracted from peripheral blood leucocytes and genotyped by Tetra-Primer Amplification Refractory Mutation System-Polymerase Chain Reaction. Serum FGF-1 concentration was evaluated with enzyme-linked immunosorbent assay. Statistical Analysis Used: The ANOVA test was used to analyse the difference between the means of the groups. Results: In RIF group, the genotype frequencies of the GG, GA and AA were 59%, 33.5% and 7.5%, respectively, whereas in controls were 72.5%, 24% and 3.5%, respectively. The G and A allele frequencies in the RIF group were 75.75% and 24.25%, while in controls were 84.5% and 15.5%, respectively (P < 0.0001). We have also shown that serum FGF-1 concentration in RIF and control groups was 17 ± 3.55 and 23.62 ± 4.91 pg/mL, respectively (P = 0.008). We have also shown that AA genotype is significantly associated with decreased serum FGF-1 concentration in RIF (AA, GA and GG serum levels were 9.55 ± 2.65, 14 ± 3.35 and 22.55 ± 7.26 pg/mL, and in controls were 12.22 ± 2.27, 18.44 ± 5.98 and 26.66 ± 8.29 pg/mL, respectively). Conclusion: The current study suggests that a significant association between FGF-1 (rs34011) promoter polymorphism and its serum concentration with RIF. The study also suggests that AA genotype is linked to lower FGF-1 serum levels and may play a risk factor for RIF.

The Effect of Progesterone Elevation on the Day of Trigger Administration: A Review of the Literature.

Since the advent of assisted reproductive technology, different variables have been shown to affect pregnancy outcomes. One of the most prevalent studied events is the premature rise in serum progesterone concentrations on the day of trigger administration during cycles of ovarian stimulation. This phenomenon, classically known as premature luteinization, has been observed significantly for decades and has been linked to adverse pregnancy outcomes and lower live birth rates. Ultimately, a quest to find a precise serum progesterone concentration cut-off value that can be effectively used to predict pregnancy outcomes prior to trigger administration is still underway. The purpose of the current research was to study the available literature on the relationship between serum progesterone on the day of trigger administration in controlled ovarian stimulation cycles used for IVF in an attempt to identify a cut-off serum progesterone concentration that can be used to effectively predict future pregnancy outcomes in fresh transfers. This study is a review of the literature and is based on information and data gathered from 36 published articles. The majority of the literature shows that a serum progesterone concentration cut-off of 1.5 ng/ml (4.77 nmol/L) can be used prior to trigger administration to effectively predict pregnancy outcomes. Premature progesterone elevation on the day or prior to the trigger administration is associated with adverse pregnancy outcomes in IVF cycles. Other factors such as follicle number, serum concentration of other hormones, and ovarian response to ovarian stimulation should also be considered to predict the success of IVF protocols.

Cyclosporine A improves the binding of mouse embryos to fibronectin.

AIM: The binding of integrin αvß3 with endometrial fibronectin (FN) promotes the migration of preimplantation embryos in mice. We have previously shown that cyclosporine A (CsA) improves the adhesion and invasion of mouse preimplantation embryos. In this study, we evaluated the roles of calcium ions and downstream signaling factors in the binding of integrin αvß3 to FN. METHODS: Female Institute of Cancer Research (ICR) mice were superovulated and mated, and two-cell embryos were harvested from the oviducts and cultured to the blastocyst stage The adhesion and stretching growth of hatched embryos in laminin-coated dishes were evaluated, and integrinß3 expression was determined using qPCR. Blastocytes were cultured with 0 or 1 µM $$ \upmu \mathrm{M} $$ cyclosporine A (CsA) and the attachment of embryonic integrin αvß3 to FN120 was observed using a fluorescent bead. To further determine the mechanism, the cells were also incubated with calcium ions and protein kinase C and calmodulin antagonists. The binding of integrin αvß3 to FN120 was examined via confocal laser scanning microscopy. RESULTS: The adhesion and stretching growth of peri-implantation embryos were greater and integrinß3 expression was higher in the 1 µM CsA group than in the 0 µM CsA group (p < 0.05). When incubated with calcium ions and protein kinase C and calmodulin antagonists, the ability of peri-implantation embryos to bind to FN decreased; CsA treatment promoted this binding. CONCLUSION: This study revealed that CsA up - regulates integrinß3 expression in peri - implantation embryos and promotes binding to FN via calcium ions, and protein kinase C, and calmodulin. These findings provide evidence supporting the beneficial effect of CsA on the peri - implantation embryo adhesion.

Decidualized Endometrial Stromal Cells Promote Mitochondrial Beta-Oxidation to Produce the Octanoic Acid Required for Implantation.

Decidualization denotes the morphological and biological differentiating process of human endometrial stromal cells (HESCs). Fatty acid pathways are critical for endometrial decidualization. However, the participation of fatty acids as an energy source and their role in endometrial decidualization have received little attention. To identify fatty acids and clarify their role in decidualization, we comprehensively evaluated free fatty acid profiles using liquid chromatography/Fourier transform mass spectrometry (LC/FT-MS). LC/FT-MS analysis detected 26 kinds of fatty acids in the culture medium of decidualized or un-decidualized HESCs. Only the production of octanoic acid, which is an essential energy source for embryonic development, was increased upon decidualization. The expressions of genes related to octanoic acid metabolism including ACADL, ACADM, and ACADS; genes encoding proteins catalyzing the first step of mitochondrial fatty acid beta-oxidation; and ACSL5 and ACSM5; genes encoding fatty acid synthesis proteins were significantly altered upon decidualization. These results suggest that decidualization promotes lipid metabolism, implying that decidualized HESCs require energy metabolism of the mitochondria in embryo implantation.

The Current Understanding of Molecular Mechanisms in Adenomyosis-Associated Infertility and the Treatment Strategy for Assisted Reproductive Technology.

Adenomyosis, endometriosis of the uterus, is associated with an increased likelihood of abnormal endometrial molecular expressions thought to impair implantation and early embryo development, resulting in disrupted fertility, including the local effects of sex steroid and pituitary hormones, immune responses, inflammatory factors, and neuroangiogenic mediators. In the recent literature, all of the proposed pathogenetic mechanisms of adenomyosis reduce endometrial receptivity and alter the adhesion molecule expression necessary for embryo implantation. The evidence so far has shown that adenomyosis causes lower pregnancy and live birth rates, higher miscarriage rates, as well as adverse obstetric and neonatal outcomes. Both pharmaceutical and surgical treatments for adenomyosis seem to have a positive impact on reproductive outcomes, leading to improved pregnancy and live birth rates. In addition, adenomyosis has negative impacts on reproductive outcomes in patients undergoing assisted reproductive technology. This association appears less significant after patients follow a long gonadotropin-releasing hormone agonist (GnRHa) protocol, which improves implantation rates. The pre-treatment of GnRHa can also be beneficial before engaging in natural conception attempts. This review aims to discover adenomyosis-associated infertility and to provide patient-specific treatment options.

Meta-analysis of intrauterine hCG perfusion efficacy in recurrent implantation failure as defined by ESHRE guidelines.

PURPOSE: This study evaluates the efficacy of intrauterine hCG perfusion for RIF, as defined by ESHRE 2023 guidelines, highlighting hCG as a cost-effective alternative to other immunotherapies, especially suitable for less developed regions. It aims to clarify treatment guidance amidst previous inconsistencies. METHODS: This meta-analysis, registered with PROSPERO (CRD42024443241) and adhering to PRISMA guidelines, assessed the efficacy and safety of intrauterine hCG perfusion in enhancing implantation and pregnancy outcomes in RIF. Comprehensive literature searches were conducted through December 2023 in major databases including PubMed, Web of Science, Embase, the Cochrane Library, and key Chinese databases, without language restrictions. Inclusion and exclusion criteria were strictly aligned with the 2023 ESHRE recommendations, with exclusions for studies lacking robust control, clear outcomes, or adequate data integrity. The risk of bias was evaluated using the Newcastle-Ottawa Scale, ROBINS-I, and RoB2 tools. Data analysis was performed in R using the 'meta' package, employing both fixed and random effect models to account for study variability. Subgroup analyses by dosage, volume, hCG concentration, timing of administration, and type of embryo transfer were conducted to deepen insights, enhancing the reliability and depth of the meta-analysis in elucidating the role of hCG perfusion in RIF treatments. RESULTS: Data from 13 studies, comprising six retrospective and six prospective studies from single centers, along with one multi-center RCT, totaling 2,157 participants, were synthesized to evaluate the effectiveness of intrauterine hCG perfusion in enhancing implantation and pregnancy outcomes in patients with RIF. Significant improvements were observed in clinical pregnancy and embryo implantation rates across various dosages, timing of administration, and embryo developmental stages, without impacting miscarriage rates. Notably, the most significant efficacy within subgroups occurred with a 500 IU dosage and perfusion parameters of ≤ 500µL volume and ≥ 2 IU/µL concentration. Additionally, a limited number of studies showed no significant increases in ectopic pregnancy or multiple pregnancy rates, and a modest improvement in live birth rates, although the small number of these studies precludes definitive conclusions. CONCLUSIONS: The analysis suggests that intrauterine hCG perfusion probably enhances embryo implantation, clinical pregnancy, and live birth rates slightly in RIF patients. Benefits are indicated with a dosage of 500 IU and a maximum volume of 500µL at concentrations of at least 2 IU/µL. However, substantial heterogeneity from varying study types and the limited number of studies necessitate cautious interpretation. These findings underscore the need for more rigorously designed RCTs to definitively assess the efficacy and safety.

Endometrial scratching in unexplained repeated implantation failure causes two competing forces, angiogenesis and anti-angiogenesis: An RCT study.

Background: A significant association between endometrial vascularity and pregnancy has been shown in previous research, while poor vascularization was attributed to repeated implantation failure (RIF). One possible approach to enhance angiogenesis for successful implantation is endometrial scratching (ES). Objective: The purpose was to investigate endometrial responses to scratching by profiling angiogenesis-related gene expression in unexplained RIF participants. Materials and Methods: In this randomized controlled trial study, 20 infertile women with unexplained RIF were assigned to 2 groups by the balanced block randomization method (n = 10/each group): the intervention group (group A) (who received ES in the follicular phase) and the control group (group B). Endometrial biopsy was performed in the secretory phase. Gene expression profiling was performed using a polymerase chain reaction-array kit for human-angiogenic growth factors. The implantation and clinical pregnancy rates were also assessed. Results: Among the angiogenesis-promoting genes, FGF1, FGF13, FGF2, TGFA, ANG, ANGPT1, and VEGFA were significantly upregulated (p < 0.05). IL12A (an angiogenesis-inhibiting cytokine) was significantly upregulated (p < 0.01). In contrast, 15 genes with angiogenesis-related functions, including CXCL11, CXCL13, CXCL3, CXCL5, CXCL6, EREG, FIGF, FST, IL10, LEP, PPBP, PROK1, RHOB, TNF, and TYMP, were downregulated after ES. No significant differences were observed between the intervention (group A) and control (group B) groups in terms of implantation (43.75% vs. 28.57%) or clinical pregnancy rates (75% vs. 57.1%). Conclusion: ES induced significant alterations in the expression of angiogenesis-related genes, with notable up/downregulation of key angiogenic/antiangiogenic factors. These findings enhance our understanding of the molecular responses triggered by ES, underscoring the potential influence of ES on the complex processes of angiogenesis crucial for implantation.

The Efficiency of Introducing Intrauterine Infusion of Autologous Platelet-Rich Plasma versus Granulocyte Colony-Stimulating Factor in Repeated Implantation Failure Patients: An Unblinded Randomised Clinical Trial.

BACKGROUND: Repeated implantation failure (RIF) refers to the condition where high quality embryos are unable to successfully implant after multiple cycles of in vitro fertilization (IVF) treatment. The aim of this study is to investigate the impact of intrauterine granulocyte colony-stimulating factor (G-CSF) and platelet-rich plasma (PRP) on pregnancy rate in patients with RIF. MATERIALS AND METHODS: The present randomised clinical trial study was conducted at the IVF Centre of Mehr Medical Institute in Rasht, Iran, from 2020 to 2022. The research consisted of 200 individuals who had experienced multiple failed cycles. These patients were randomised into two groups: intrauterine infusion of 1 ml of G-CSF and intrauterine infusion of 1 ml autologous PRP at least 48 hours before embryo transfer (ET). The groups were compared in terms of implantation rate, and chemical, clinical, and ongoing pregnancy. RESULTS: The implantation rate was significantly higher in patients who received PRP (P=0.016). Chemical pregnancy in the PRP group was significantly higher than G-CSF group (P=0.003). Both clinical pregnancy and ongoing pregnancy rates were significantly higher in the PRP group (P=0.001) compared to the G-CSF group (P=0.02). CONCLUSION: The utilisation of PRP via intrauterine infusion is considerably more successful than G-CSF in enhancing pregnancy and live birth rates among patients with RIF.

Roles of lipid mediators in early pregnancy events.

Background: Early pregnancy events, including embryo implantation, are critical for maintaining a healthy pregnancy and facilitating childbirth. Despite numerous signaling pathways implicated in establishing early pregnancy, a comprehensive understanding of implantation remains elusive. Methods: This paper provides a comprehensive review of the current research on lipids in the context of early pregnancy, with a particular focus on feto-maternal communications. Main Findings: Embryo implantation entails direct interaction between uterine tissues and embryos. Introducing embryos triggers significant changes in uterine epithelial morphology and stromal differentiation, facilitating embryo implantation through communication with uterine tissue. Studies employing genetic models and chemical compounds targeting enzymes and receptors have elucidated the crucial roles of lipid mediators-prostaglandins, lysophosphatidic acid, sphingosine-1-phosphate, and cannabinoids-in early pregnancy events. Conclusion: Given the high conservation of lipid synthases and receptors across species, lipid mediators likely play pivotal roles in rodents and humans. Further investigations into lipids hold promise for developing novel diagnostic and therapeutic approaches for infertility in humans.

The synergy of morphokinetic parameters and sHLA-G in cleavage embryo enhancing implantation rates.

Objective: This study aimed to assess the relationship between implantation and soluble HLA-G (sHLA-G) expression in cleavage embryo culture medium (ECM) in conjunction with early developmental kinetics determined by time-lapse imaging (TLI). Methods: A retrospective, single-center study was conducted involving 238 embryos from 165 patients who underwent Frozen-thawed embryo transfer (FET) using autologous oocytes, with either single or double embryo transfer. TLI morphokinetic parameters (t2, t3, t4, t5, t6, t7, t8, cc2, s2, cc3, s3) of embryos were analyzed, and sHLA-G levels in D3 ECM were measured using an enzyme-linked immunosorbent assay (ELISA). A hierarchical classification model was developed to categorize embryos into five groups (A, B, C, D, E). The correlation between sHLA-G levels, TLI classification of embryos, and embryo implantation was investigated to establish a non-invasive method for evaluating implantation potential. Multivariate logistic regression analysis was performed to identify potential influencing factors, and receiver operating characteristic (ROC) curves were used to evaluate the predictive value for implantation. Results: Multivariate unconditional logistic regression analysis indicated that TLI parameters t5 and s3 and sHLA-G level in ECM were independent risk factors affecting embryo implantation. The implantation rate decreased from TLI classification A to E. The proposed classification model effectively assessed the implantation potential of embryos. The implantation rate was higher in the sHLA-G positive group compared to the sHLA-G negative group (p < 0.001). The expression of sHLA-G in D3 ECM, combined with the TLI classification model, accurately evaluated the implantation potential of embryos with an AUC of 0.876. Conclusion: The integration of cleavage kinetics and embryonic sHLA-G expression could reliably identify embryos with a high likelihood of successful implantation.

Do extracellular vesicles have specific target cells?; Extracellular vesicle mediated embryo maternal communication.

Extracellular vesicles (EVs) serve as messengers for intercellular communication, yet the precise mechanisms by which recipient cells interpret EV messages remain incompletely understood. In this study, we explored how the origin of EVs, their protein cargo, and the recipient cell type influence the cellular response to EVs within an embryo implantation model. We treated two types of EVs to 6 different recipient cell types and expression of zinc finger protein 81 (ZNF81) gene expression in the recipient cells were quantified using quantitative polymerase chain reaction (qPCR). The proteomic contents of the EV cargos were also analyzed. The results showed that downregulation of the ZNF81 gene was a specific cellular response of receptive endometrial epithelial cells to trophoblast derived EVs. Protein cargo analysis revealed that the proteomic profile of EVs depends on their cell of origin and therefore may affect the recipient cell response to EVs. Furthermore, trophoblastic EVs were found to be specifically enriched with transcription factors such as CTNNB1 (catenin beta-1), HDAC2 (histone deacetylase 2), and NOTCH1 (neurogenic locus notch homolog protein 1), which are known regulators of ZNF81 gene expression. The current study provided compelling evidence supporting the existence of EV specificity, where the characteristics of both the EVs and the recipient cell type collectively contribute to regulating EV target specificity. Additionally, EV protein cargo analysis suggested a potential association between transcription factors and the specific functionality of trophoblastic EVs. This in vitro embryo implantation model and ZNF81 read-out provides a unique platform to study EV specific functionality in natural cell-cell communication.

A transient transcriptional activation governs unpolarized-to-polarized morphogenesis during embryo implantation.

During implantation, embryos undergo an unpolarized-to-polarized transition to initiate postimplantation morphogenesis. However, the underlying molecular mechanism is unknown. Here, we identify a transient transcriptional activation governing embryonic morphogenesis and pluripotency transition during implantation. In naive pluripotent embryonic stem cells (ESCs), which represent preimplantation embryos, we find that the microprocessor component DGCR8 can recognize stem-loop structures within nascent mRNAs to sequester transcriptional coactivator FLII to suppress transcription directly. When mESCs exit from naive pluripotency, the ERK/RSK/P70S6K pathway rapidly activates, leading to FLII phosphorylation and disruption of DGCR8/FLII interaction. Phosphorylated FLII can bind to transcription factor JUN, activating cell migration-related genes to establish poised pluripotency akin to implanting embryos. Resequestration of FLII by DGCR8 drives poised ESCs into formative pluripotency. In summary, we identify a DGCR8/FLII/JUN-mediated transient transcriptional activation mechanism. Disruption of this mechanism inhibits naive-poised-formative pluripotency transition and the corresponding unpolarized-to-polarized transition during embryo implantation, which are conserved in mice and humans.

The therapeutic effects of vitamin D3 administration on the embryo implantation.

Various adjuvants have been tested clinically for patients with problems with embryo implantation during in vitro fertilization (IVF)-embryo transfer (ET). Vitamin D3, an essential modulator of various physiological processes, has received attention as an important adjuvant for successful pregnancy, as many studies have shown a strong association between vitamin D deficiency and implantation failure and fetal growth restriction. However, vitamin D has been widely utilized in different protocols, resulting in non-reproducible and debatable outcomes. In the present study, we demonstrated that cyclic intrauterine administration of vitamin D3 increased endometrial receptivity and angiogenesis, which could be attributed to increased recruitment of uterus-resident natural killer cells. In particular, cyclic treatment of vitamin D3 promoted stable attachment of the embryo onto endometrial cells in vitro, suggesting its merit during the early stage of embryo implantation to support the initial maternal-fetal interactions. Our findings suggest that women with repeated implantation failure may benefit from the use of vitamin D3 as a risk-free adjuvant prior to IVF-ET procedures to improve the uterine environment, and make it favorable for embryo implantation.

Effect of 3D and 2D cell culture systems on trophoblast extracellular vesicle physico-chemical characteristics and potency.

The growing understanding of the role of extracellular vesicles (EVs) in embryo-maternal communication has sparked considerable interest in their therapeutic potential within assisted reproductive technology, particularly in enhancing implantation success. However, the major obstacle remains the large-scale production of EVs, and there is still a gap in understanding how different culture systems affect the characteristics of the EVs. In the current study, trophoblast analogue human chorionic carcinoma cell line was cultivated in both conventional monolayer culture (2D) and as spheroids in suspension culture (3D) and how the cell growth environment affects the physical, biochemical and cellular signalling properties of EVs produced by them was studied. Interestingly, the 3D system was more active in secreting EVs compared to the 2D system, while no significant differences were observed in terms of morphology, size, and classical EV protein marker expression between EVs derived from the two culture systems. There were substantial differences in the proteomic cargo profile and cellular signalling potency of EVs derived from the two culture systems. Notably, 2D EVs were more potent in inducing a cellular response in endometrial epithelial cells (EECs) compared to 3D EVs. Therefore, it is essential to recognize that the biological activity of EVs depends not only on the cell of origin but also on the cellular microenvironment of the parent cell. In conclusion, caution is warranted when selecting an EV production platform, especially for assessing the functional and therapeutic potential of EVs through in vitro studies.

LnCRNAs in the Regulation of Endometrial Receptivity for Embryo Implantation.

The development of endometrial receptivity is crucial for successful embryo implantation and the initiation of pregnancy. Understanding the molecular regulatory processes that transform the endometrium into a receptive phase is essential for enhancing implantation rates in fertility treatments, such as in vitro fertilization (IVF). Long non-coding RNAs (lncRNAs) play a pivotal role as gene regulators and have been examined in the endometrium. This review offers current insights into the role of lncRNAs in regulating endometrial receptivity. Considering the significant variation in endometrial remodeling among species, we summarize the key events in the human endometrial cycle and discuss the identified lncRNAs in both humans and other species, which may play a crucial role in establishing receptivity. Notably, there are 742 lncRNAs in humans and 4438 lncRNAs that have the potential to modulate endometrial receptivity. Additionally, lncRNAs regulating matrix metalloproteinases (MMPs) and Let-7 have been observed in both species. Future investigations should explore the potential of lncRNAs as therapeutic targets and/or biomarkers for diagnosing and improving endometrial receptivity in human fertility therapy.

Effect and mechanism of Hashimoto thyroiditis on female infertility: A clinical trial, bioinformatics analysis, and experiments-based study.

Diagnosing Hashimoto thyroiditis (HT) relies on thyroglobulin antibody (TgAb) and thyroid peroxidase antibody (TPOAb) titers. The influence of these antibodies on female infertility remains a subject of debate. This study aims to explore the effect and mechanism of HT on female infertility. First, a single-center cross-sectional study was conducted to investigate whether TgAb and TPOAb are the key factors leading to female infertility. Second, bioinformatic analysis was performed to investigate the potential target molecules and pathways. Third, in vivo experiments were performed to explore the effects of elevated TgAb levels on embryo implantation in a mouse model of autoimmune thyroiditis (AIT). Four hundred and five infertile women and 155 healthy controls were enrolled in the cross-sectional study. Results indicated that the TPOAb titer was associated with female infertility, while the TgAb titer showed no significant association. The increased levels of TgAb and TPOAb are not significantly correlated with anti-Mullerian hormone. Bioinformatic analysis indicated that the common target molecules for HT and female infertility include interleukin (IL)-6, IL-10, matrix metalloproteinase 9, and tumor necrosis factor, suggesting potential regulation through multiple signaling pathways such as HIF-1, VEGF, MAPK, and Th17 cell differentiation. A certain dose of porcine thyroglobulin can successfully establish a mouse model of AIT. In this mouse model, embryo implantation and ovarian reserve remain unaffected by elevated TgAb levels. In conclusion, the serum TPOAb titer was associated with infertility due to female factors but the TgAb titer showed no significant association. A simple increase in serum TgAb titer does not affect embryo implantation and ovarian reserve in the AIT model.

The effect of folic acid supplementation and folate deficiency on embryo implantation.

Implantation is a critical stage of pregnancy, which occurs in a short period of interaction between the receptive endometrium and the embryo. Folic acid (FA) is a synthetic derivative of folate and is recommended as a pre-conceptional supplement. However, the impact of different doses of FA supplementation and folate deficiency during the early stages of pregnancy requires further investigation. The aim of this study was to investigate the possible effects of FA supplementation and folate deficiency on expression of Estrogen Receptor Alpha (ER-α), Vascular Endothelial Growth Factor-A (VEGFA), and Integrin alpha V and beta3 (Integrin αVß3). A total of 32, 6-8-week old Wistar albino rats were divided into four groups of control, folate-deficiency, low-dose, and high-dose FA supplement groups. After five weeks of FA supplementation and folate deficiency model formation, mated rats were sacrificed on the 5th gestational day (GD), and implantation sites were collected. The expression of ER- α, VEGFA, and Integrin αVß3 in the implantation sites were examined with immunohistochemistry and real-time PCR. The results revealed that the mRNA levels of ESR1, VEGFA, and Integrin αV and ß3 were significantly increased in the high-dose FA group and significantly decreased in the folate deficiency group compared to the control group (p < 0.05). Based on these results, it can be concluded that FA supplementation before pregnancy has positive effects on the maintenance of pregnancy, and folate deficiency may lead to implantation disorders.

Murine uterine gland branching is necessary for gland function in implantation.

Uterine glands are branched, tubular structures whose secretions are essential for pregnancy success. It is known that pre-implantation glandular expression of leukemia inhibitory factor (LIF) is crucial for embryo implantation; however, the contribution of uterine gland structure to gland secretions, such as LIF, is not known. Here, we use mice deficient in estrogen receptor 1 (ESR1) signaling to uncover the role of ESR1 signaling in gland branching and the role of a branched structure in LIF secretion and embryo implantation. We observed that deletion of ESR1 in neonatal uterine epithelium, stroma, and muscle using the progesterone receptor PgrCre causes a block in uterine gland development at the gland bud stage. Embryonic epithelial deletion of ESR1 using a Müllerian duct Cre line, Pax2Cre, displays gland bud elongation but a failure in gland branching. Reduction of ESR1 in adult uterine epithelium using the lactoferrin-Cre (LtfCre) displays normally branched uterine glands. Unbranched glands from Pax2Cre Esr1flox/flox uteri fail to express glandular pre-implantation Lif, preventing implantation chamber formation and embryo alignment along the uterine mesometrial-antimesometrial axis. In contrast, branched glands from LtfCre Esr1flox/flox uteri display reduced expression of ESR1 and glandular Lif resulting in delayed implantation chamber formation and embryo-uterine axes alignment but mice deliver a normal number of pups. Finally, pre-pubertal unbranched glands in control mice express Lif in the luminal epithelium but fail to express Lif in the glandular epithelium, even in the presence of estrogen. These data strongly suggest that branched glands are necessary for pre-implantation glandular Lif expression for implantation success. Our study is the first to identify a relationship between the branched structure and secretory function of uterine glands and provides a framework for understanding how uterine gland structure-function contributes to pregnancy success.