胚泡着床窗口的分子调控

着床窗口是指当胚胎发育到胚泡阶段时,子宫也增殖和分化到可接受状态,二者相互作用使胚泡着床的短暂时间.雌激素和孕酮是该过程的综合调控分子,它们通过多种局部信号分子的介导,使子宫中的各种细胞类型增殖、分化,为着床窗口的开放做出相互协调的反应.子宫与胚胎在着床窗口通过前列腺素、组织胺、降钙素、多种细胞因子和生长因子的旁分泌作用进行分子对话,使胚泡滋养层与子宫内膜上皮发生附着反应.着床窗口一旦开放,即自动向非接受态转化.     

S100 protein family and embryo implantation

It is well known that embryo implantation is a critical process in which embryo should be able to reach and attach to endometrium. Until now, various types of factors are involved in the regulation of this process. S100 proteins are calcium-binding proteins, which have vital roles in embryo implantation and have been considered as possible candidate markers for endometrial receptivity. However, studies regarding mode of actions of these proteins are scarce and more mechanistic insights are needed to clarify exact roles of each one of the S100 protein family. Understanding of function of these proteins in different compartments, stages, and phases of endometrium, could pave the way for conducting studies regarding the therapeutic significance of these proteins in some disorders such as recurrent implantation failure. In this review, we outlined roles and possible underlying mechanisms of S100 protein family in embryo implantation.     

Regulated expression of heparin-binding EGF-like growth factor (HB-EGF) in the human endometrium: a potential paracrine role during implantation

Heparin-binding epidermal growth factor (HB-EGF) is a recently identified member of the EGF growth factor family found to be expressed in the uterus of both mouse and human at the time of implantation. In the present study, we investigated the expression patterns of HB-EGF in normal cycling endometrium and compared its expression with the fertility-associated endometrial epithelial biomarkers alpha(v)beta(3) integrin, leukemia inhibitory factor (LIF) and homeobox gene, HOXA-10. RNase protection assay (RPA) using RNA made from endometrium collected from different phases of the menstrual cycle demonstrated increased HB-EGF expression during the mid-secretory phase, a pattern similar to, but slightly preceding the expression of alpha(v)beta(3) integrin and HOXA-10. In vitro studies demonstrated stimulation of HB-EGF expression by estradiol-17beta (E(2)) and progesterone (P(4)) alone or in combination in stromal cells. Combined treatment with E(2) + P(4) was, however, required to stimulate epithelial HB-EGF expression. In vitro experiments demonstrated the ability of HB-EGF to stimulate epithelial expression of the key endometrial proteins including LIF, HOXA-10, and the beta(3) integrin subunit. Each has previously been demonstrated to be an important epithelial biomarker expressed during the implantation window. In addition, conditioned media from endometrial stromal cells treated with E(2) + P(4) + relaxin mimicked the stimulatory effect of HB-EGF on epithelial expression of the beta(3) integrin subunit. The stimulatory effect of the stromal-conditioned medium was blocked by antibodies that neutralize a known receptor for HB-EGF. These data suggest that uterine receptivity may be regulated in part by the stromal-derived HB-EGF.     

Decreased ANGPTL4 impairs endometrial angiogenesis during peri‐implantation period in patients with recurrent implantation failure

Insufficient endometrial angiogenesis during peri‐implantation impairs endometrial receptivity (ER), which contributes to recurrent implantation failure (RIF) during in vitro fertilization and embryo transfer (IVF‐ET). Angiopoietin‐like protein 4 (ANGPTL4) acts as a multifunctional secretory protein and is involved in the regulation of lipid metabolism and angiogenesis in various tissues including the endometrium. Herein, we found decreased ANGPTL4 expression in endometrial tissue and serum during peri‐implantation period in 18 RIF‐affected women with elevated uterine arterial impedance (UAI) compared with the pregnancy controls. ANGPTL4 and peroxisome proliferator‐activated receptor gamma (PPARγ) expression were up‐regulated upon decidualization on human endometrial stromal cells (HESCs). Rosiglitazone promoted the expression of ANGPTL4 in HESCs and human umbilical vein endothelial cells (HUVECs) via PPARγ. ANGPTL4 promoted the proliferation, migration and angiogenesis of HUVECs in vitro. Our results suggest that decreased abundance of ANGPTL4 in endometrial tissues impairs the endometrial receptivity via restraining endometrial angiogenesis during decidualization; while rosiglitazone‐induced ANGPTL4 up‐regulation in hESCs and HUVECs through PPARγ. Therefore, ANGPTL4 could be a potential therapeutic approach for some RIF‐affected women with elevated UAI.     

Potential innate immunity-related markers of endometrial receptivity and recurrent implantation failure (RIF)

The successful implantation of the embryo into a receptive endometrium is essential for the establishment of a viable pregnancy while recurrent implantation failure (RIF) is a real challenge in assisted reproduction. The maternal innate immune system, specifically the Toll-like receptors (TLRs), are involved in maintaining immunity in the female reproductive tract (FRT) required for fertility. In this study, we aimed to investigate the importance of innate immunity-related gene expression in the regulation of human fertility and as a prediction of potential outcome of in vitro fertilization - embryo transfer (IVF-ET), thus, we assessed the gene expression levels of TLR signalling molecules using quantitative real-time PCR between endometrial biopsies of healthy fertile women, and the patients experiencing RIF. Interestingly, our results showed that, TRIB2 and TLR9 genes were differentially expressed between the endometrial biopsies of healthy women and those with RIF. However, comparing expression levels of same genes between pre-receptive and receptive healthy endometrial biopsies showed different genes (ICAM1, NFKBIA, VCAM1, LIF, VEGFB, TLR5) had significantly altered expression, suggesting their involvement in endometrial receptivity. Thus, further investigations will enable us to better understand the role of these genes in the biology of FRT and as a possible target for the improvement of infertility treatments and/or development of non-hormonal contraception.     

IVF-ET时影响胚胎着床率的因素分析

胚胎移植成功的标志性事件是胚胎着床。着床是一个高度协调的事件,影响胚胎着床的因素主要有胚胎质量和子宫内膜容受性两方面。     

子宫内膜容受性检测技术在反复种植失败患者冻融胚胎移植中的应用价值及其临床妊娠的影响因素分析

摘要 目的：探讨子宫内膜容受性检测（ERT）技术在反复种植失败患者冻融胚胎移植（FET）中的应用价值,并分析其临床妊娠的影响因素。方法：回顾性分析2019年10月~2022年4月期间海南省妇女儿童医学中心收治的150例反复种植失败患者的临床资料,根据是否接受ERT技术分为ERT组（n=78,接受ERT技术）和无ERT组（n=72,未接受ERT技术）。按照反复种植失败患者是否临床妊娠分为临床妊娠组和未临床妊娠组。采用单因素和多因素Logistic回归模型分析临床妊娠的影响因素。结果：两组异位妊娠率组间对比未见统计学差异（P>0.05）。ERT组临床妊娠率、活产率高于无ERT组,移植日内膜厚度大于无ERT组,移植胚胎数少于无ERT组,流产率低于无ERT组（P<0.05）。所有患者按照是否临床妊娠分为临床妊娠组（n=85）和未临床妊娠组（n=65）。单因素分析结果显示：临床妊娠与年龄、移植胚胎类别、移植胚胎数量、总周期数、FSH、子宫内膜厚度、子宫内膜类型有关（P<0.05）,而与体质量指数（BMI）、不孕年限、不孕类型、胚胎冷冻保存时间无关（P>0.05）。多因素Logistic回归分析结果显示：年龄偏大、FSH偏高是临床妊娠的危险因素,而移植胚胎类别为囊胚、移植胚胎数量偏多是临床妊娠的保护因素（P<0.05）。结论：ERT技术用于反复种植失败患者FET中,可有效改善患者的临床妊娠。年龄、FSH、移植胚胎类别、移植胚胎数量是临床妊娠的影响因素。     

Endometrium implantation and ectopic pregnancy

Embryo in uterine implantation is a complex and multifactor-related process and is a downstream and ideal point for woman fertility control.Understanding the cellular and molecular mechanism of implantation is a prerequisite for development of anti-implantation contraceptives.In spite of considerable accumulation of information from the laboratory animals that has been achieved,it is difficult to generate such information in human due to ethical restriction and experimental limitation,and the present knowledge for understanding the definitive mechanisms which control these events remains elusive.Embryo implantation can also occur outside uterus.Some women with abdominal pregnancies could successfully complete the processes of gestation and bear normal babies,implying that implantation itself may be not an endometrium-specific process.Reproductive biologists should cooperate with gynecologists to further comparatively study the molecular and cellular mechanisms of implantation normally occurring in endometrium and abnormally appearing outside uterine cavity.Such collaborative studies may generate new important information for developing anti-implantation contraceptive and for techniques of accurate diagnosis of ectopic pregnancy.A specially designed GnRH-2 analog and a combination use of Iow dose RU486 and gossypol as anti-implantation contraceptives have been suggested.     

Endometrium implantation and ectopic pregnancy

~~Endometrium implantation and ectopic pregnancy~~     

乳酸菌阴道胶囊辅助治疗在行ART反复着床失败患者中的应用

探究行辅助生殖技术（ART）反复着床失败患者应用乳酸菌阴道胶囊辅助治疗对子宫内膜容受性（ER）和阴道微生物的影响。

选取2020年5月至2022年5月本院收治ART反复着床失败患者100例,根据治疗方式分为观察组（n = 50）和对照组（n = 50）。对照组采用常规治疗,观察组采用常规治疗联合乳酸菌阴道胶囊。比较两组的性激素水平（雌二醇、孕酮）,内膜容积、子宫内膜厚度、血管血流指数（VFI）、内膜血流指数（FI）和阻力指数（RI）等子宫内膜容受性指标,阴道pH值、阴道菌群检出率和乳酸菌数量。

两组治疗前后血清雌二醇、孕酮水平比较,差异无统计学意义（P＞0.05）。两组治疗前子宫内膜厚度、内膜容积、血管血流指数、内膜血流指数和阻力指数比较,差异无统计学意义（P＞0.05）。治疗后观察组子宫内膜厚度、内膜容积和血管血流指数均高于治疗前（P＜0.01）和对照组（P＜0.05）。治疗前两组菌群检出率差异无统计学意义（P＞0.05）,治疗后两组菌群检出率均低于治疗前（P＜0.05）,治疗后观察组菌群检出率低于对照组（P＜0.05）。两组阴道pH值均低于治疗前（P＜0.001）,治疗后观察组阴道pH值低于对照组（P＜0.001）。两组阴道乳杆菌正常率均高于治疗前（P＜0.05）,治疗后观察组高于对照组（P＜0.05）。两组胚胎着床率、临床妊娠率、早期流产率和持续妊娠率差异无统计学意义（P＞0.05）。

乳酸菌阴道胶囊治疗ART反复着床失败患者可以改善子宫内膜容受性和阴道菌群。

     

Changes in calcium levels in the endometrium throughout pregnancy and the role of calcium on endometrial gene expression at the time of conceptus implantation in pigs

Calcium plays an essential role in regulating many cellular functions, including proliferation, differentiation, and apoptosis. In spite of its importance in the establishment and maintenance of pregnancy, changes in calcium levels at the maternal–conceptus interface during pregnancy and its action on endometrial gene expression are not well understood. Thus, we examined changes in calcium levels in the endometrium during pregnancy, calcium deposition at the maternal–conceptus interface during pregnancy, and the role of calcium on the expression of endometrial genes related to conceptus implantation during early pregnancy in pigs. The amounts of endometrial calcium increased during mid‐ to late pregnancy, and calcium deposition was mainly localized to endometrial and chorionic epithelial cells at the maternal–conceptus interface during pregnancy and conceptus tissues during early pregnancy. The amounts of total recoverable calcium in uterine flushings were greater on Day 12 of pregnancy than Day 12 of the estrous cycle, and estrogen increased absorption of calcium ions by endometrial tissues. Increasing endometrial calcium levels by treatment with A23187, a calcium ionophore, decreased the expression of the estrogen‐responsive endometrial genes AKR1B1, ESR1, FGF7, IL1RAP, LPAR3, S100G, SPP1, and STC1 and increased the expression of genes related to prostaglandin synthesis and transport, namely PTGES, PTGS2, and SLCO5A1. These data suggest that calcium ions at the maternal–conceptus interface play a critical role in the establishment and maintenance of pregnancy in pigs by regulating the expression of endometrial genes involved in conceptus implantation, as well as the attachment of endometrial epithelial and conceptus trophectoderm/chorionic epithelial cells during pregnancy.     

Physiological and molecular determinants of embryo implantation

Embryo implantation involves the intimate interaction between an implantation-competent blastocyst and a receptive uterus, which occurs in a limited time period known as the window of implantation. Emerging evidence shows that defects originating during embryo implantation induce ripple effects with adverse consequences on later gestation events, highlighting the significance of this event for pregnancy success. Although a multitude of cellular events and molecular pathways involved in embryo–uterine crosstalk during implantation have been identified through gene expression studies and genetically engineered mouse models, a comprehensive understanding of the nature of embryo implantation is still missing. This review focuses on recent progress with particular attention to physiological and molecular determinants of blastocyst activation, uterine receptivity, blastocyst attachment and uterine decidualization. A better understanding of underlying mechanisms governing embryo implantation should generate new strategies to rectify implantation failure and improve pregnancy rates in women.     

Effects of GnRH antagonist on endometrial protein profiles in the window of implantation

GnRH antagonists can suppress luteinizing hormone and follicle‐stimulating hormone (FSH), with less initial stimulatory effect and lower risk of ovarian hyperstimulation syndrome. The effects of GnRH antagonists on embryonic implantation remain controversial. To evaluate the effects of GnRH antagonists, endometrial tissues were biopsied from 12 women with intracytoplasmic sperm injection treatment, in which four subjects undergoing controlled ovulation stimulation with rFSH and GnRH antagonist, four subjects with a GnRH agonist long protocol, and four natural cycle controls. After iTRAQ quantification analysis, 24 proteins showed differential expression between natural cycle and agonist treatment group and 39 proteins between natural cycle and antagonist treatment group. A total of seven proteins demonstrated differential expression only in antagonist treatment group. Bioinformatic analysis implied these proteins can function in cell processes including angiogenesis, cell proliferation, apoptosis, cell migration, and immune response. Furthermore, GnRH antagonist suppressed the function of GNAS and ANPEP, which were important for endometrial functions. Immunohistochemical staining showed that ANPEP was mainly localized in the human endometrial stroma, while ACO2, CDC5L, and GNAS were mainly localized in the glands. This study could provide insights into the effect of GnRH antagonists on the endometrium, and help optimize the embryo implantation and improve the success rate for GnRH antagonist protocol.     

Characterization of secretory leukocyte protease inhibitor as an inhibitor of implantation serine proteinases

We have recently identified and characterized two implantation serine proteinase genes, ISP1 and ISP2, which give rise to a dimeric proteinase, ISP that facilitates embryo invasion during peri-implantation period. As many proteinases have cognate serpins that regulate their proteolytic activity, we have been investigating anti-tryptases, expressed during this window of implantation. Here, we report the differential expression of secretory leukocyte protease inhibitor (SLPI) in uterine endometrium around the implantation period. The co-localization of SLPI and ISP suggests the possibility that SLPI is an ISP serpin and that expression of SLPI may lead to a reduction in ISP activity. The expression of SLPI is down regulated during the window of embryo-uterine receptivity. Our results are consistent with a model suggesting that the drop in SLPI expression may help to refine the opening of the window of implantation, by allowing the proteolytic activity of embryo invasive serine proteinases such as the ISPs.     

肿瘤转移抑制因子基因MRP-1/CD9对小鼠胚胎着床影响的研究

目的研究外源性MRP-1/CD9抗体对小鼠胚胎着床的影响。方法1.将8-细胞小鼠胚胎培养于含不同浓度MRP-1/CD9抗体的培养液中,观察囊胚形成及囊胚脱透明带的情况。2.妊娠D4小鼠子宫角注射MRP-1/CD9抗体,于妊娠D8观察小鼠胚胎植入数量。结果1.体外培养时,MRP-1/CD9抗体显著抑制胚胎的囊胚形成率(1:400,P<0.05)和脱带率(1∶800,P<0.05)。2.宫角注射MRP-1/CD9抗体可以显著提高小鼠胚胎的着床数(8.33±0.15vs4.57±0.21)。结论MRP-1/CD9参入小鼠胚胎的发育及植入。     

N-glycosylation of uterine endometrium determines its receptivity

Glycosylation alters the molecular and functional features of glycoproteins, which is closely related with many physiological processes and diseases. During “window of implantation”, uterine endometrium transforms into a receptive status to accept the embryo, thereby establishing successful embryo implantation. In this article, we aimed at investigating the role of N-glycosylation, a major modification type of glycoproteins, in the process of endometrial receptivity establishment. Results found that human uterine endometrial tissues at mid-secretory phase exhibited Lectin PHA-E+L (recognizes the branched N-glycans) positive N-glycans as measured by the Lectin fluorescent staining analysis. By utilizing in vitro implantation model, we found that de-N-glycosylation of human endometrial Ishikawa and RL95-2 cells by tunicamycin (inhibitor of N-glycosylation) and peptide-N-glycosidase F (PNGase F) impaired their receptive ability to human trophoblastic JAR cells. Meanwhile, N-glycosylation of integrin αvβ3 and leukemia inhibitory factor receptor (LIFR) are found to play key roles in regulating the ECM-dependent FAK/Paxillin and LIF-induced STAT3 signaling pathways, respectively, thus affecting the receptive potentials of endometrial cells. Furthermore, in vivo experiments and primary mouse endometrial cells-embryos coculture model further verified that N-glycosylation of mouse endometrial cells contributed to the successful implantation. Our results provide new evidence to show that N-glycosylation of uterine endometrium is essential for maintaining the receptive functions, which gives a better understanding of the glycobiology of implantation.     

GABA consumption during early pregnancy impairs endometrial receptivity and embryo development in mice

γ‐Aminobutyrate (GABA) is commonly used as a food supplement and a health care product by young females, due to its positive roles in relieving stress, alleviating anxiety, and improving sleep. However, its recommended daily dose in different products varies widely. Besides, it is unknown whether, and how, GABA consumption during early pregnancy influences pregnancy establishment. In this study, we found that when pregnant mice were treated with a high (12.5 mg/g) dose of GABA (orally) during preimplantation, there was a reduction in the number of implantation sites on day 5 of pregnancy. Also, among these unimplanted embryos, most exhibited morphological degeneration and developmental retardation, and only a few of them developed into blastocysts but could not implant into the uterus. Moreover, the expression of uterine receptivity–related factors—LIF, E‐cadherin, and HOXA10—were all downregulated, while the number of uterine glands was reduced in the high GABA dose group. Finally, in vitro results demonstrated that GABA (ranging from 10 to 50 μg/μL) markedly inhibited preimplantation embryo development in a dose‐response manner. However, this inhibitory effect was not observed when the embryos were pretreated with 40 μΜ 2‐hydroxysaclofen, a GABA_B antagonist, indicating that GABA exerts its inhibitory effects via its B‐type receptor. Our results suggest that exposure to certain GABA concentrations, during early pregnancy, can impair preimplantation embryo development via its B‐type receptor, and endometrial receptivity, which greatly disturbs early embryo implantation in mice. These findings could raise concerns about GABA consumption during the early stages of pregnancy.     

Proteomic Insights into Endometrial Receptivity and Embryo‐Endometrial Epithelium Interaction for Implantation Reveal Critical Determinants of Fertility

In vitro fertilization has overcome infertility issues for many couples. However, achieving implantation of a viable embryo into the maternal endometrium remains a limiting step in optimizing pregnancy success. The molecular mechanisms which characterize the transient state of endometrial receptivity, critical in enabling embryo‐endometrial interactions, and proteins which underpin adhesion at the implantation interface, are limited in humans despite these temporally regulated processes fundamental to life. Hence, failure of implantation remains the “final frontier” in infertility. A human coculture model is utilized utilizing spheroids of a trophectoderm (trophoblast stem) cell line, derived from pre‐implantation human embryos, and primary human endometrial epithelial cells, to functionally identify “fertile” versus “infertile” endometrial epithelium based on adhesion between these cell types. Quantitative proteomics identified proteins associated with human endometrial epithelial receptivity (“epithelial receptome”) and trophectoderm adhesion (“adhesome”). As validation, key “epithelial receptome” proteins (MAGT‐1/CDA/LGMN/KYNU/PC4) localized to the epithelium of receptive phase (mid‐secretory) endometrium obtained from fertile, normally cycling women but is largely absent from non‐receptive (proliferative) phase tissues. Factors involved in embryo‐epithelium interaction in successive temporal stages of endometrial receptivity and implantation are demonstrated and potential targets for improving fertility are provided, enhancing potential to become pregnant either naturally or in a clinical setting.     

17Beta-estradiol induces nuclear translocation of CrkL at the window of embryo implantation

Crk family adaptors are widely expressed and mediate the timely formation of signal transduction protein complexes upon a variety of extracellular stimuli, including various growth and differentiation factors. The window of implantation is the favorable time period when the uterus develops a receptive approach to the invading embryo. Various signaling cascades are likely to become active at the window of implantation both in the uterus and the embryo. This helps create maternal embryo dialogue leading to successful embryo implantation. In this study we report for the first time the presence and nuclear translocation of the adaptor molecule CrkL both in the uterine and embryonic partners at the window of implantation. We also report that estrogen, which initiates and guides crucial changes in the uterus and the embryo at the window of receptivity, causes a massive surge in the expression and subsequent nuclear translocation of CrkL. We have also identified the existence of one LXXLL motif in the CrkL amino acid sequence and a single LXD is sufficient for activation by the estrogen receptor. This is suggestive that CrkL can bind to estrogen receptors and act as a coactivator.