Oviductal glycoprotein 1 (OVGP1) is expressed by endometrial epithelium that regulates receptivity and trophoblast adhesion

Role of HOXA10 in pathologies of the endometrium

HOXA10 belongs to the homeobox gene family and is essential for uterine biogenesis, endometrial receptivity, embryo implantation, and stromal cell decidualization. Available evidence suggests that the expression of HOXA10 is dysregulated in different endometrial disorders like endometrial hyperplasia, endometrial cancer, adenomyosis, endometriosis, recurrent implantation failure, and unexplained infertility. The downregulation of HOXA10 occurs by genetic changes in the HOXA10 gene, methylation of the HOXA10 locus, or selected miRNAs. Endocrine disruptors and organic pollutants also cause the reduced expression of HOXA10 in these conditions. In vivo experiments in mouse models and in vitro studies in human cell lines demonstrate that downregulation of HOXA10 leads to endometrial epithelial cell proliferation, failure of stromal cell decidualization, altered expression of genes involved in cell cycle regulation, immunomodulation, and various signaling pathways. These disruptions are speculated to cause infertility associated with the disorders of the endometrium.

Uterine cyclin A2-deficient mice as a model of female early pregnancy loss

Proper action of the female sex steroids 17β-estradiol (E2) and progesterone (P4) on the endometrium is essential for fertility. Beyond its role in regulating the cell cycle, cyclin A2 (CCNA2) also mediates E2 and P4 signaling in vitro, but a potential role in modulating steroid action for proper endometrial tissue development and function is unknown. To fill this gap in our knowledge, we examined human endometrial tissue from fertile and infertile cisgender women for CCNA2 expression and correlated this with pregnancy outcome. Functional assessment of CCNA2 was validated in vivo using a conditional Ccna2 uterine-deficient mouse model, while in vitro function was assessed using human cell culture models. We found that CCNA2 expression was significantly reduced in endometrial tissue, specifically the stromal cells, from women undergoing in vitro fertilization who failed to achieve pregnancy. Conditional deletion of Ccna2 from mouse uterine tissue resulted in an inability to achieve pregnancy, which appeared to be due to alterations in the process of decidualization, which was confirmed using in vitro models. From these studies, we conclude that CCNA2 expression during the proliferative/regenerative stage of the menstrual cycle allows for proper steroid responsiveness, decidualization, and pregnancy. When CCNA2 expression levels are insufficient, there is impaired endometrial responsiveness, aberrant decidualization, and loss of pregnancy.

White Isthmus Transcriptome Analysis Reveals the Mechanism of Translucent Eggshell Formation

The presence of translucent eggshells is a type of egg quality issue that impacts egg sales. While many researchers have studied them, the exact mechanisms behind their formation remain unclear. In this study, we conducted a transcriptomic differential expression analysis of the isthmus region of the oviduct in both normal egg- and translucent egg-laying hens. The analysis revealed that differentially expressed gene pathways were predominantly concentrated in the synthesis, modification, and transport of eggshell membrane proteins, particularly collagen proteins, which provide structural support. These findings suggest that variations in the physical structure of the eggshell membrane, resulting from changes in its chemical composition, are the fundamental cause of translucent eggshell formation. This research provides a theoretical reference for reducing the occurrence of translucent eggs.

MiRNA-miRNA interaction network in peripheral blood of patients with myocardial infarction: a gene expression meta-analysis

In recent years, investigations have revealed that microRNAs (miRNAs) can bind together and form a miRNA-miRNA-mRNA regulatory network that alters the consequence of miRNA-mRNA interaction. If we consider the miRNA that binds to mRNA as the primary miRNA and the miRNA that binds to the primary miRNA as the secondary one, secondry miRNAs can act as master regulators upstream of primary miRNAs and their target mRNAs. One of the distinguishing characteristics of secondary miRNAs as master regulators within a diverse set of differentially expressed genes is the absence of direct target mRNA for them. Instead, these master regulators exclusively govern the regulation of miRNAs that target specific mRNAs. Through in silico analysis, we identified 18 miRNAs among 385 differentially expressed miRNAs (DEmiRNAs) with no direct target mRNAs among 58 differentially expressed mRNAs (DEmRNAs) in peripheral blood of patients with myocardial infarction (MI). Instead, these secondary miRNAs targeted 9 primary miRNAs that had 36 direct targets among 58 DEmRNAs. We found that one primary miRNA might be regulated by more than one secondary miRNAs and each secondary miRNA can target more than one primary miRNAs. Among identified miRNA-miRNA-mRNA networks miR-188-5p/miR-299-3p/natural killer cell granule protein (NKG7), miR-200a-3p/miR-199b-5p/granzyme B (GZMB), and miR-377-3p/miR-581/oviductal glycoprotein 1 (OVGP1) exhibited higher scors in terms of expression levels (>2-fold increase or decrease) and strengh of interactions (ΔG < -5). Given the extensive network of miRNA interactions, focusing on master regulators opens up avenues for identifying key regulatory nodes for more effective therapeutic strategies.

The role of extracellular vesicles from placenta and endometrium in pregnancy: Insights from tumor biology

Extracellular vesicles (EVs) are small membrane-bound particles secreted by various cell types that play a critical role in intercellular communication by packaging and delivering biomolecules. In recent years, EVs have emerged as essential messengers in mediating physiological and pathological processes in tumor biology. The tumor microenvironment (TME) plays a pivotal role in tumor generation, progression, and metastasis. In this review, we provide an overview of the impact of tumor-derived EVs on both tumor cells and the TME. Moreover, we draw parallels between tumor biology and pregnancy, as successful embryo implantation also requires intricate intercellular communication between the placental trophecepiblast and the endometrial epithelium. Additionally, we discuss the involvement of EVs in targeting immune responses, trophoblast invasion, migration, and angiogenesis, which are shared biological processes between tumors and pregnancy. Specifically, we highlight the effects of placenta-derived EVs on the fetal-maternal interface, placenta, endometrium, and maternal system, as well as the role of endometrium-derived EVs in embryo-endometrial communication. However, challenges still exist in EVs research, including the standardization of EVs isolation methods for diagnostic testing, which also apply to reproductive systems where EVs-mediated communication is proposed to take place. Through this review, we aim to deepen the understanding of EVs, particularly in the context of reproductive biology, and encourage further investigation in this field.

The lncRNA LINC00339-encoded peptide promotes trophoblast adhesion to endometrial cells via MAPK and PI3K-Akt signaling pathways

BACKGROUND

Endometrial receptivity (ER), a pivotal event for successful embryo implantation, refers to the capacity of endometrium to allow the adhesion of the trophectoderm of the blastocyst to endometrial cells. In this paper, we set to elucidate whether the peptides encoded by lncRNAs could influence trophoblast cells' adhesion to endometrial cells.

METHODS

WGCNA construction and bioinformatics were used to find out the ER-related lncRNAs with coding potential. Protein analysis was done by immunoblotting and immunofluorescence (IF) microscopy. CCK-8 and Calcein-AM/PI double staining assays were employed to evaluate cell viability. The effect of the peptide on trophoblast spheroids' adhesion to endometrial cells was evaluated. The RNA sequencing (RNA-seq) analysis was applied to identify downstream molecular processes.

RESULTS

lncRNA LINC00339 was found to be related to ER development and it had been predicted to have protein-coding potential. LINC00339 had high occupancy of ribosomes and was confirmed to encode a 49-aa peptide (named LINC00339-205-49aa). LINC00339-205-49aa could promote the attachment of JAR trophoblast spheroids to Ishikawa endometrial cells in vitro. LINC00339-205-49aa also upregulated the expression of E-cadherin in Ishikawa cells. Mechanistically, MAPK and PI3K-Akt signaling pathways were involved in the modulation of LINC00339-205-49aa, which were activated by LINC00339-205-49aa in Ishikawa cells.

CONCLUSION

These data demonstrate that a previously uncharacterized peptide encoded by lncRNA LINC00339 has the ability to enhance JAR trophoblast spheroids' adhesion to Ishikawa endometrial cells, highlighting a new opportunity for the development of drugs to improve ER.

Proteomic Approaches to Unravel the Molecular Dynamics of Early Pregnancy in Farm Animals: An In-Depth Review

Infertility is a major problem in farm animals, which has a negative economic effect on farm industries. Infertility can be defined as the inability of animals to achieve a successful pregnancy. Early pregnancy is crucial to establish a successful pregnancy, and it is reported that 70-80% and 20-30% of total embryonic loss occur in cattle and pigs, respectively, during the first month of pregnancy. The advanced high-throughput proteomics techniques provide valuable tools for in-depth understanding of the implantation process in farm animals. In the present review, our goal was to compile, assess, and integrate the latest proteomic research on farm animals, specifically focused on female reproduction, which involves endometrial tissues, uterine fluids, oviductal fluids, and microRNAs. The series of studies has provided in-depth insights into the events of the implantation process by unfolding the molecular landscape of the uterine tract. The discussed data are related to pregnant vs. non-pregnant animals, pregnancy vs. oestrous cycle, different days of the early pregnancy phase, and animals with uterine infections affecting reproduction health. Some of the studies have utilized non-invasive methods and in vitro models to decipher the molecular events of embryo-maternal interaction. The proteomics data are valuable sources for discovering biomarkers for infertility in ruminants and new regulatory pathways governing embryo-uterine interaction, endometrium receptivity, and embryonic development. Here, we envisage that the identified protein signatures can serve as potential therapeutic targets and biomarkers to develop new therapeutics against pregnancy diseases.

HIF-1α is positively associated with endometrial receptivity by regulating PKM2

PURPOSE

Numerous advancements have been introduced into the field of assisted reproductive technology (ART) in the past four decades. Nonetheless, implantation failure is still a key limiting step for a successful pregnancy. Building of endometrial receptivity (ER) is essential for successful implantation. However, the fundamental biological processes and mechanisms of ER remain elusive. Our study investigates the function of hypoxia inducible factor-1α (HIF-1α) during ER establishment and shed lights on the novel molecular mechanism by which HIF-1α regulates ER-related gene expression network.

METHODS

Levels of HIF-1α, homeobox A10 (HOXA10), insulin-like growth factor-binding protein 1 (IGFBP1), pyruvate kinase M2 (PKM2), and lactate dehydrogenase A (LDHA) in endometrial tissues were measured via real-time PCR, immunoblotting and immunohistochemistry. The correlation between HIF-1α and HOXA10, IGFBP1, PKM2, LDHA were analyzed separately. Ishikawa cells were treated with vector HIF-1α, HIF-1α-siRNA, and PKM2-siRNA. After transfection, the levels of HOXA10, IGFBP1, LDHA, and PKM2 were measured via real-time PCR and immunoblotting, and the lactate concentrations and cell migration of Ishikawa cells were measured.

RESULTS

Levels of HIF-1α, IGFBP1, HOXA10, LDHA, and PKM2 were significantly decreased in recurrent implantation failure (RIF) patients and levels of HOXA10, IGFBP1, PKM2, and LDHA were correlated with HIF-1α in endometrium. Then in a cellular model established by HIF-1α vector and HIF-1α-siRNA, the expression of HOXA10, IGFBP1, LDHA, PKM2, and lactate concentrations were dramatically upregulated and downregulated. And the expression of HOXA10, and IGFBP1 were dramatically decreased by PKM2-siRNA.

CONCLUSIONS

HIF-1α plays a crucial role in the building of ER through regulating glycolysis.

Chitinases and chitinase-like proteins in asthma

Despite the lack of endogenous chitin synthesis, mammalian genomes encode two enzymatically active true chitinases (chitotriosidase and acidic mammalian chitinase) and a variable number of chitinase-like proteins (CLPs) that have no enzyme activity but bind chitin. Chitinases and CLPs are prominent components of type-2 immune response-mediated respiratory diseases. However, despite extensive research into their role in allergic airway disease, there is still no agreement on whether they are mere biomarkers of disease or actual disease drivers. Functions ascribed to chitinases and CLPs include, but are not limited to host defense against chitin-containing pathogens, directly promoting inflammation, and modulating tissue remodeling and fibrosis. Here, we discuss in detail the chitin-dependent and -independent roles of chitinases and CLPs in the context of allergic airway disease, and recent advances and emerging concepts in the field that might identify opportunities for new therapies.

Immune alterations in recurrent implantation failure

A failure to achieve pregnancy after three or more embryo transfer cycles with high-quality blastocysts is referred to as recurrent implantation failure (RIF). RIF can be due to altered uterine factors or male factors or embryo factors. Disrupted endometrial receptivity, altered expression of genes in several pathways, immunologic disturbances in the peripheral blood and/or the endometrium, and epigenetic alterations are associated with RIF. Amongst the immunologic disturbances, altered Th1/Th2 ratio, altered NK cell and macrophage numbers are observed in women with RIF. However, not all women with RIF have the same kind of immune dysfunction suggesting that RIF is a heterogeneous condition associated with varied immune responses and one size may not fit all. Thus, personalized therapies based on the immune status of the patient are being tested in women with RIF. In general, women with a high Th1/Th2 ratio are offered Tacrolimus, while intravenous IgG is recommended in women with high NK cell numbers/HLA mismatch. Women with hyperactivated immune status in the uterus are offered progesterone support, prednisolone, vitamin E, and intralipid treatment to suppress inflammation and oxidative stress, while endometrial scratching and intrauterine hCG administration are offered to women with hypo-active immune status. There is a need for standardized tests for evaluation of immune status in patients and sufficiently powered randomized controlled trials for personalized therapies to determine which of these will be beneficial in women with RIF. Till then, the ART community should limit the use of such add-on interventions in women with RIF.

Oviduct Epithelial Cell-Derived Extracellular Vesicles Improve Porcine Trophoblast Outgrowth

Porcine species have a great impact on studies on biomaterial production, organ transplantation and the development of biomedical models. The low efficiency of in vitro-produced embryos to derive embryonic stem cells has made achieving this goal a challenge. The fallopian tube plays an important role in the development of embryos. Extracellular vesicles (EVs) secreted by oviductal epithelial cells play an important role in the epigenetic regulation of embryo development. We used artificially isolated oviductal epithelial cells and EVs. In this study, oviductal epithelial cell (OEC) EVs were isolated and characterized through transmission electron microscopy, nanoparticles tracking analysis, western blotting and proteomics. We found that embryo development and blastocyst formation rate was significantly increased (14.3% ± 0.6% vs. 6.0% ± 0.6%) after OEC EVs treatment. According to our data, the inner cell mass (ICM)/trophectoderm (TE) ratio of the embryonic cell number increased significantly after OEC EVs treatment (43.7% ± 2.3% vs. 28.4% ± 2.1%). Meanwhile, the attachment ability of embryos treated with OEV EVs was significantly improved (43.5% ± 2.1% vs. 29.2% ± 2.5%, respectively). Using quantitative polymerase chain reaction (qPCR), we found that the expression of reprogramming genes (POU5F1, SOX2, NANOG, KLF4 and c-Myc) and implantation-related genes (VIM, KRT8, TEAD4 and CDX2) significantly increased in OEC EV-treated embryos. We report that OEC EV treatment can improve the development and implantation abilities of embryos.

The role of oviduct-specific glycoprotein (OVGP1) in modulating biological functions of gametes and embryos

Diverse lines of evidence indicate that the mammalian oviduct makes important contributions to the complex process of reproduction other than being simply a conduit for the transport of gametes and embryos. The cumulative synthesis and transport of proteins secreted by oviductal secretory cells into the oviductal lumen create a microenvironment supporting important reproductive events, including sperm capacitation, fertilization, and early embryo development. Among the components that have been identified in the oviductal fluid is a family of glycosylated proteins known collectively as oviduct-specific glycoprotein (OVGP1) or oviductin. OVGP1 has been identified in several mammalian species, including humans. The present review summarizes the work carried out, in various mammalian species, by many research groups revealing the synthesis and secretion of OVGP1, its fate in the female reproductive tract upon secretion by the oviductal epithelium, and its role in modulating biological functions of gametes and embryos. The production and functions of recombinant human OVGP1 and recombinant OVGP1 of other mammalian species are also discussed. Some of the findings obtained with immunocytochemistry will be highlighted in the present review. It is hoped that the findings obtained from recent studies carried out with recombinant OVGP1 from various species will rekindle researchers’ interest in pursuing further the role of the oviductal microenvironment, of which OVGP1 is a major component, in contributing to the successful occurrence of early reproductive events, and the potential use of OVGP1 in improving the current assisted reproductive technology in alleviating infertility.

Modulation of E-Cadherin and N-Cadherin by ovarian steroids and embryonic stimuli

Endometrium is a dynamic tissue that undergoes extensive remodelling to attain a receptive state which is further modulated in presence of an embryo for successful initiation of pregnancy. Cadherins are the proteins of the junctional complex of which E-cadherin (E-Cad) is crucial for maintaining epithelial cell state and integrity of the epithelial barrier; gain of N-cadherin (N-Cad) in epithelial cells leads to epithelial to mesenchymal transition (EMT). In the present study, we investigated the expression of E-Cad and N-Cad in the mouse endometrial luminal epithelium and its modulation by estrogen, progesterone, and embryonic stimuli. We observed that E-Cad is diffusely expressed in the luminal epithelium of mouse endometrium during the estrus stage and upon estrogen treatment. It is apico-laterally and basolaterally sorted at the diestrus stage and in response to the combined treatment of estrogen and progesterone. In 3D spheroids of human endometrial epithelial cells, combined treatment with estrogen and progesterone led to lateral sorting of E-Cad without any effects on its mRNA levels. at the time of embryo implantation, there is loss of E-Cad along with the gain of N-Cad and SNAIL expression suggestive of EMT in the luminal epithelium. This EMT is possibly driven by embryonic stimuli as treatment with estrogen and progesterone did not lead to the gain of N-Cad expression in the mouse endometrium in vivo or in human endometrial epithelial cells in vitro. In conclusion, the present study demonstrates that steroid hormones directly affect E-Cad sorting in the endometrial epithelium which undergo EMT in response to embryonic stimuli.

Host Genetic Risk Factors for Chlamydia trachomatis-Related Infertility in Women

BACKGROUND

Chlamydia trachomatis (Ct) infection ascending to the upper genital tract can cause infertility. Direct association of genetic variants as contributors is challenging because infertility may not be diagnosed until years after infection. Investigating the intermediate trait of ascension bridges this gap.

METHODS

We identified infertility genome-wide association study (GWAS) loci using deoxyribonucleic acid from Ct-seropositive cisgender women in a tubal factor infertility study and Ct-infected cisgender women from a longitudinal pelvic inflammatory disease cohort with known fertility status. Deoxyribonucleic acid and blood messenger ribonucleic acid from 2 additional female cohorts with active Ct infection and known endometrial infection status were used to investigate the impact of infertility single-nucleotide polymorphisms (SNPs) on Ct ascension. A statistical mediation test examined whether multiple infertility SNPs jointly influenced ascension risk by modulating expression of mediator genes.

RESULTS

We identified 112 candidate infertility GWAS loci, and 31 associated with Ct ascension. The SNPs altered chlamydial ascension by modulating expression of 40 mediator genes. Mediator genes identified are involved in innate immune responses including type I interferon production, T-cell function, fibrosis, female reproductive tract health, and protein synthesis and degradation.

CONCLUSIONS

We identified Ct-related infertility loci and their potential functional effects on Ct ascension.

Extracellular vesicles in embryo implantation and disorders of the endometrium

Implantation of the embryo is a rate-limiting step for a successful pregnancy, and it requires an intricate crosstalk between the embryo and the endometrium. Extracellular vesicles (EVs) are membrane-enclosed, nano-sized structures produced by cells to mediate cell to cell communication and modulate a diverse set of biological processes. Herein, we review the involvement of EVs in the process of embryo implantation and endometrial diseases. EVs have been isolated from uterine fluid, cultured endometrial epithelial/stromal cells and trophectodermal cells. The endometrial epithelial and stromal/decidual cell-derived EVs and its cargo are internalized bythe trophoblast cells, and they regulate a diverse set of genes involved in adhesion, invasion and migration. Conversely, the embryo-derived EVs and its cargo are internalized by epithelial and immune cells of the endometrium for biosensing and immunomodulation required for successful implantation. EVs have also been shown to play a role in infertility, recurrent implantation failure, endometriosis, endometritis and endometrial cancer. Further research should set a stage for EVs as non-invasive "liquid biopsy" tools for assessment of endometrial health.

Hypoxia and its possible relationship with endometrial receptivity in adenomyosis: a preliminary study

BACKGROUND

Adenomyosis (AM) is an important cause of female infertility. However, the underlying mechanism remains unclear. This report describes a preliminary study of hypoxia and its possible association with endometrial receptivity in AM.

METHODS

The study was divided into in vitro and in vivo experiments. In vitro, expression levels of the endometrial receptivity markers HOXA10 and HOXA11 in the implantation period were examined using real-time PCR and western blotting. Endometrial expression of hypoxia-inducible factor (HIF)-1α, HIF-2α, and HIF-3α was determined using immunohistochemistry. In vivo, using an AM mouse model established by oral administration of tamoxifen, we inhibited expression of HIF-2α using an HIF-2α antagonist (PT2399; 30 mg/kg body weight, twice daily by oral gavage for 2 days) and then examined expression levels of Hoxa10 and Hoxa11 using real-time PCR and western blotting.

RESULTS

Endometrial mRNA and protein expression levels of HOXA10 and HOXA11 were significantly lower in patients with AM than in control patients. Expression of HIF-2α was significantly higher in the AM group than in the control group, whereas that of HIF-1α and HIF-3α was equivalent in both groups. In vivo analysis showed that administration of the HIF-2α antagonist resulted in increased expression of Hoxa10 and Hoxa11 at both the mRNA and protein levels in AM model mice.

CONCLUSIONS

HIF-2α overexpression may be one reason for decreased endometrial receptivity in AM. The current findings provide insight into HIF-2α-mediated AM-related infertility and suggest that PT2399 has potential as a treatment for AM.

TRIAL REGISTRATION

This trial was retrospectively registered.

A Comparative View on the Oviductal Environment during the Periconception Period

The oviduct plays important roles in reproductive events: sperm reservoir formation, final gamete maturation, fertilization and early embryo development. It is well known that the oviductal environment affects gametes and embryos and, ultimately, the health of offspring, so that in vivo embryos are better in terms of morphology, cryotolerance, pregnancy rates or epigenetic profile than those obtained in vitro. The deciphering of embryo-maternal interaction in the oviduct may provide a better understanding of the embryo needs during the periconception period to improve reproductive efficiency. Here, we perform a comparative analysis among species of oviductal gene expression related to embryonic development during its journey through the oviduct, as described to date. Cross-talk communication between the oviduct environment and embryo will be studied by analyses of the secreted or exosomal proteins of the oviduct and the presence of receptors in the membrane of the embryo blastomeres. Finally, we review the data that are available to date on the expression and characterization of the most abundant protein in the oviduct, oviductin (OVGP1), highlighting its fundamental role in fertilization and embryonic development.

MRAP2 regulates endometrial receptivity and function

A successful embryo implantation depends on the synchronization between a competent blastocyst and a receptive endometrium. Recently, potential modulators of endometrial receptivity (OVGP1, MRAP2, ZCCHC12, and HAP1) have been reported likely with a functional role during embryo implantation. The aim of this study was to evaluate the gene expression of these genes in the endometrium of infertile women. Eighteen endometrial biopsies, during secretory lutheal phase, were recruited from women with unexplained infertility and women who cannot conceive due to their partners' fertility problems. qRT-PCR was carried out to evaluate MRAP2, OVGP1, ZCCHC12 and HAP1 gene expression. MRAP2 expression was also detected by western blot and it was localized by immunohistochemistry. Morphological analysis was performed by light microscopy. MRAP2 was significantly up-regulated in study vs. control group. Western blot analysis confirmed the observed MRAP2 up-expression. MRAP2 resulted mainly localized in the epithelial cells of uterine glands. Morphological analysis displayed that the epithelium of the uterine glands undergo hypertrophy in women with unexplained infertility in respect to women with male infertility factor. MRAP2 could be considered a mediator of endometrial receptivity likely acting on endometrial stability by binding to MCRs and PKR1.