Role of Slit2/Robo1 in trophoblast invasion and vascular remodeling during ectopic tubal pregnancy

An Integrative ATAC-Seq and RNA-Seq Analysis of the Endometrial Tissues of Meishan and Duroc Pigs

Meishan pigs are a well-known indigenous pig breed in China characterized by a high fertility. Notably, the number of endometrial grands is significantly higher in Meishan pigs than Duroc pigs. The characteristics of the endometrial tissue are related to litter size. Therefore, we used the assay for transposase-accessible chromatin with sequencing (ATAC-seq) and RNA-sequencing (RNA-seq) to analyze the mechanisms underlying the differences in fecundity between the breeds. We detected the key transcription factors, including Double homeobox (Dux), Ladybird-like homeobox gene 2 (LBX2), and LIM homeobox 8 (Lhx8), with potentially pivotal roles in the regulation of the genes related to endometrial development. We identified the differentially expressed genes between the breeds, including SOX17, ANXA4, DLX3, DMRT1, FLNB, IRF6, CBFA2T2, TFCP2L1, EFNA5, SLIT2, and CYFIP2, with roles in epithelial cell differentiation, fertility, and ovulation. Interestingly, ANXA4, CBFA2T2, and TFCP2L1, which were upregulated in the Meishan pigs in the RNA-seq analysis, were identified again by the integration of the ATAC-seq and RNA-seq data. Moreover, we identified genes in the cancer or immune pathways, FoxO signaling, Wnt signaling, and phospholipase D signaling pathways. These ATAC-seq and RNA-seq analyses revealed the accessible chromatin and potential mechanisms underlying the differences in the endometrial tissues between the two types of pigs.

Abnormal expression of SLIT3 induces intravillous vascularization dysplasia in ectopic pregnancy

Objective

To investigate whether the morphology, capillary number, and transcriptome expression profiles of ectopic pregnancy (EP) villi differ from those of normal pregnancy (NP) villi.

Methods

Hematoxylin-eosin (HE) and immunohistochemistry (IHC) staining for CD31 were conducted to compare differences in morphology and capillary number between EP and NP villi. Differentially expressed (DE) miRNAs and mRNAs were determined from transcriptome sequencing of both types of villi and used to construct a miRNA-mRNA network, from which hub genes were identified. Candidate DE-miRNAs and DE-mRNAs were validated by quantitative reverse transcription (qRT)-PCR. Correlations were identified between the number of capillaries and serum beta human chorionic gonadotropin (β-HCG) levels and between the expression levels of hub genes associated with angiogenesis and β-HCG levels.

Results

The mean and total cross-sectional areas of placental villi were significantly increased in EP compared with NP villi. Capillary density was greatly reduced in EP villi and was positively correlated with β-HCG levels. A total of 49 DE-miRNAs and 625 DE-mRNAs were identified from the sequencing data. An integrated analysis established a miRNA-mRNA network containing 32 DE-miRNAs and 103 DE-mRNAs. Based on the validation of hub mRNAs and miRNAs in the network, a regulatory pathway involving miR-491-5p-SLIT3 was discovered, which may have a role in the development of villous capillaries.

Conclusion

Villus morphology, capillary number, and miRNA/mRNA expression profiles in villous tissues were aberrant in EP placentas. Specifically, SLIT3, which is regulated by miR-491-5p, may contribute to the regulation of villous angiogenesis and was established as a putative predictor of chorionic villus development, providing a basis for future research.

Trophoblastic infiltration of tubal pregnancy may have an association with chronic inflammation of the fallopian tube

OBJECTIVE

To explore the factors associated with trophoblastic infiltration in ampullary pregnancy from the perspective of clinical and pathologic characteristics.

METHODS

A single-center, retrospective, clinicopathologic cohort study was conducted in women who were diagnosed with tubal pregnancy and underwent salpingectomy in the International Peace Maternal and Child Health Care Hospital from January 2018 to June 2021.

RESULTS

A total of 333 eligible women diagnosed with ampullary pregnancy were included in the analysis. Multivariate logistic analysis showed that preoperative β-human chorionic gonadotropin greater than 3000 IU/L (adjusted odds ratio [aOR] 3.77, 95% confidence interval [CI] 2.02-7.03), and vascular remodeling phenomenon (aOR 4.34, 95% CI 2.41-7.83) were positively correlated with the infiltration of extravillous trophoblasts into serosa, while presence of chronic inflammation of the fallopian tube was a negatively corellated factor (aOR 0.49, 95% CI 0.29-0.85).

CONCLUSION

The depth of trophoblastic infiltration in tubal pregnancy may be related to the presence of chronic inflammation in the fallopian tube. A tubal pregnancy in a tube with chronic salpingitis is more likely to develop into an abortive ectopic pregnancy; whereas in a fallopian tube without chronic inflammation, the risk of it developing into a ruptured ectopic pregnancy increases. Hence, early identification is needed to properly address this dangerous pregnancy situation.

Role of microRNAs in trophoblast invasion and spiral artery remodeling: Implications for preeclampsia

It is now well-established that microRNAs (miRNAs) are important regulators of gene expression. The role of miRNAs in placental development and trophoblast function is constantly expanding. Trophoblast invasion and their ability to remodel uterine spiral arteries are essential for proper placental development and successful pregnancy outcome. Many miRNAs are reported to be dysregulated in pregnancy complications, especially preeclampsia and they exert various regulatory effects on trophoblasts. In this review, we provide a brief overview of miRNA biogenesis and their mechanism of action, as well as of trophoblasts differentiation, invasion and spiral artery remodeling. We then discuss the role of miRNAs in trophoblasts invasion and spiral artery remodeling, focusing on miRNAs that have been thoroughly investigated, especially using multiple model systems. We also discuss the potential role of miRNAs in the pathogenesis of preeclampsia.

[Talin1 is highly expressed in the fallopian tube and chorionic villi to promote trophoblast invasion in tubal pregnancy]

OBJECTIVE

To investigate the expression of Talin1 in the fallopian tube and chorionic villi in patients with tubal pregnancy and its role in regulating invasion and migration of trophoblasts.

METHODS

Immunohistochemistry and Western blotting were used to detect the localization and expression level of Talin1 in the fallopian tube and chorionic villi in patients with tubal pregnancy and in women with normal pregnancy. In the cell experiment, HTR-8/SVneo cells was transfected with Talin1 siRNA and the changes in cell invasion and migration were assessed using scratch assay and Transwell assay. The expressions of MMP-2, MMP-9, N-cadherin and Snail in the transfected cells were detected by qRT-PCR and Western blotting.

RESULTS

Positive expression of Talin1 was detected in both normal fallopian tube tissues and tissues from women tubal pregnancy, and its expression was localized mainly in the cytoplasm of cilia cells. The expression level of Talin1 was significantly higher in both the fallopian tube and chorionic villi in women with tubal pregnancy than in normal fallopian tube and chorionic villi samples (P < 0.01). In HTR-8/SVneo cells, transfection with Talin1 siRNA significantly inhibited cell invasion (P < 0.01) and migration (P < 0.05), down-regulated the expression of N-cadherin, MMP-2 and Snail (P < 0.05), and up-regulated the expression of MMP-9 in the cells (P < 0.05).

CONCLUSION

The expression of Talin1 in the fallopian tube and chorionic villi is significantly increased in women with tubal pregnancy, suggesting the association of Talin1-regulated trophoblast cell invasion with the occurrence of tubal pregnancy.

Molecular Mechanisms Underlying the Association between Endometriosis and Ectopic Pregnancy

Endometriosis is a common inflammatory disease characterized by the presence of endometrial cells outside the uterine cavity. It is estimated that it affects 10% of women of reproductive age. Its pathogenesis covers a wide range of abnormalities, including adhesion, proliferation, and cell signaling disturbances. It is associated with a significant deterioration in quality of life as a result of chronic pelvic pain and may also lead to infertility. One of the most serious complications of endometriosis is an ectopic pregnancy (EP). Currently, the exact mechanism explaining this phenomenon is unknown; therefore, there are no effective methods of prevention. It is assumed that the pathogenesis of EP is influenced by abnormalities in the contraction of the fallopian tube muscles, the mobility of the cilia, and in the fallopian microenvironment. Endometriosis can disrupt function on all three levels and thus contribute to the implantation of the embryo beyond the physiological site. This review takes into account aspects of the molecular mechanisms involved in the pathophysiology of endometriosis and EP, with particular emphasis on the similarities between them.

The Role of Slit-2 in Gestational Diabetes Mellitus and Its Effect on Pregnancy Outcome

BACKGROUND

Slit guidance ligand 2 (Slit-2), as a member of the Slit family, can regulate the inflammatory response and glucose metabolism. The purpose of this study was to explore the expression of Slit-2 in maternal peripheral blood and neonatal cord blood of gestational diabetes mellitus (GDM) patients and its potential importance in disease progression.

METHODS

This study included 57 healthy pregnant women and 61 GDM patients. The levels of Slit-2, C-reactive protein (CRP), monocyte chemoattractant protein-1 (MCP-1), C-peptide (C-P), galectin-3(Gal-3), HbA1c, fasting blood glucose (FBG) and fasting insulin (FINS) in maternal peripheral blood and neonatal cord blood were detected by ELISA. Spearman's rank correlation test was used to assess the association between peripheral Slit-2 and inflammatory indicators, insulin resistance, and pregnancy outcomes. Logistic regression analysis was used to analyze the risk factors of GDM.

RESULTS

Slit-2 levels in maternal peripheral blood and neonatal cord blood of the GDM patients were higher than those of the HC. Slit-2 levels in maternal peripheral blood and neonatal cord blood of the GDM patients were positively correlated with inflammatory factors CRP and MCP-1 levels. The level of Slit-2 in the maternal peripheral blood of the GDM patients was positively correlated with the level of homeostasis model assessment insulin resistance (HOMA-IR) and HbA1c in maternal peripheral blood, but was negatively correlated with the level of homeostasis model assessment -β (HOMA-β). We also found that the Slit-2 level in the maternal peripheral blood of the GDM patients was negatively correlated with neonatal blood glucose, positively correlated with neonatal weight and independent of neonatal total bilirubin.

CONCLUSION

Our study suggests that the abnormal increase in Slit-2 in GDM may be related to its pathogenesis, and it was correlated with neonatal blood glucose and weight in patients with GDM, suggesting that Slit-2 may be a potential biomarker of GDM.

Role of Slit2 upregulation in recurrent miscarriage through regulation of stromal decidualization

INTRODUCTION

Knockout mouse model has shown a relationship between Slit2/Robo1 signalling and altered fertility. Altered expression by endometrial epithelium and trophoblast and is associated with the pathogenesis of pregnancy complications but few studies have investigated the expression of decidual Slit2 in miscarriage.

METHODS

Expression profiles of Slit2 and Robo1 were measured in human endometrial tissues during the menstrual cycle phases (n = 30), in decidua tissues from recurrent miscarriage (n = 20) and healthy control (n = 20) at 6-8 weeks of gestation. The hormonal regulation of Slit2/Robo1 expression and the role of Slit2/Robo1 signalling in decidualization was investigated in vitro, along with its effects on β-catenin and MET expression.

RESULTS

In human endometrium, Slit2 and Robo1 protein expression in stromal cells were decreased between the late-proliferative and early-secretory phase. In recurrent miscarriage patients, decidual expression Slit2 was increased and associated with lower expression of E-cadherin and higher level vimentin compared to controls. In vitro, the expression of Slit2 was downregulated by cAMP and progesterone in hESCs. Upregulation of Slit2 resulted in inhibition of cell decidualization and β-catenin translocation to nucleus.

DISCUSSION

This study indicates a functional role for Slit2 in endometrial stromal cell decidualization and the pathogenesis of recurrent miscarriage. Aberrant Increase in Slit2 expression may impairs decidualization of endometrial stromal cells leading to recurrent in recurrent miscarriage.

[Long non-coding RNAs show different expression profiles and display competing endogenous RNA potential in placenta accreta spectrum disorders]

OBJECTIVE

To investigate the expression profile of long non-coding RNAs (lncRNA) and identify potential lncRNA-related competing endogenous RNAs (ceRNA) in placenta accrete spectrum disorders (PAS).

METHODS

Five tissue specimens of placental implantation and 5 adjacent normal placental tissues were collected from cesarean section deliveries complicated by PAS in our hospital between December, 2017 and June, 2018. Human microarrays were used to identify the lncRNAs that were differentially expressed in PAS, and 5 of the identified lncRNAs were further validated using qRT-PCR. GO and KEGG pathway analyses were performed to indentify the most significant enrichment functions. A ceRNA network was constructed based on ENST00000511361 (RP5-875H18.4), NR_027457 (LINC00221) and NR_126415 (FOXP4-AS1) to pinpoint the potential lncRNAs-related ceRNA.

RESULTS

A total of 329 lncRNAs and 179 mRNAs were identified to have differential expression in PAS. The results of qRT-PCR were consistent with the human microarrays results. Transforming growth factor-β (TGF-β) signaling pathway was the most significantly enriched pathway. The constructed ceRNA network suggested that RP5-875H18.4--miRNA-218--SLIT2 had a potential ceRNA regulatory mechanism in PAS.

CONCLUSIONS

The differentially expressed lncRNAs are involved in the occurrence and progression of PAS possibly by regulating the TGF-β signaling pathway. The ceRNA network of RP5-875H18.4--miRNA-218--SLIT2 may play a role in the occurrence of PAS.

Identification of loci associated with conception rate in primiparous Holstein cows

BACKGROUND

Subfertility is a major issue facing the dairy industry as the average US Holstein cow conception rate (CCR) is approximately 35%. The genetics underlying the physiological processes responsible for CCR, the proportion of cows able to conceive and maintain a pregnancy at each breeding, are not well characterized. The objectives of this study were to identify loci, positional candidate genes, and transcription factor binding sites (TFBS) associated with CCR and determine if there was a genetic correlation between CCR and milk production in primiparous Holstein cows. Cows were bred via artificial insemination (AI) at either observed estrus or timed AI and pregnancy status was determined at day 35 post-insemination. Additive, dominant, and recessive efficient mixed model association expedited (EMMAX) models were used in two genome-wide association analyses (GWAA). One GWAA focused on CCR at first service (CCR1) comparing cows that conceived and maintained pregnancy to day 35 after the first AI (n = 494) to those that were open after the first AI (n = 538). The second GWAA investigated loci associated with the number of times bred (TBRD) required for conception in cows that either conceived after the first AI (n = 494) or repeated services (n = 472).

RESULTS

The CCR1 GWAA identified 123, 198, and 76 loci associated (P < 5 × 10- 08) in additive, dominant, and recessive models, respectively. The TBRD GWAA identified 66, 95, and 33 loci associated (P < 5 × 10- 08) in additive, dominant, and recessive models, respectively. Four of the top five loci were shared in CCR1 and TBRD for each GWAA model. Many of the associated loci harbored positional candidate genes and TFBS with putative functional relevance to fertility. Thirty-six of the loci were validated in previous GWAA studies across multiple breeds. None of the CCR1 or TBRD associated loci were associated with milk production, nor was their significance with phenotypic and genetic correlations to 305-day milk production.

CONCLUSIONS

The identification and validation of loci, positional candidate genes, and TFBS associated with CCR1 and TBRD can be utilized to improve, and further characterize the processes involved in cattle fertility.

Risk of spontaneous preterm birth and fetal growth associates with fetal SLIT2

Spontaneous preterm birth (SPTB) is the leading cause of neonatal death and morbidity worldwide. Both maternal and fetal genetic factors likely contribute to SPTB. We performed a genome-wide association study (GWAS) on a population of Finnish origin that included 247 infants with SPTB (gestational age [GA] < 36 weeks) and 419 term controls (GA 38-41 weeks). The strongest signal came within the gene encoding slit guidance ligand 2 (SLIT2; rs116461311, minor allele frequency 0.05, p = 1.6×10-6). Pathway analysis revealed the top-ranking pathway was axon guidance, which includes SLIT2. In 172 very preterm-born infants (GA <32 weeks), rs116461311 was clearly overrepresented (odds ratio 4.06, p = 1.55×10-7). SLIT2 variants were associated with SPTB in another European population that comprised 260 very preterm infants and 9,630 controls. To gain functional insight, we used immunohistochemistry to visualize SLIT2 and its receptor ROBO1 in placentas from spontaneous preterm and term births. Both SLIT2 and ROBO1 were located in villous and decidual trophoblasts of embryonic origin. Based on qRT-PCR, the mRNA levels of SLIT2 and ROBO1 were higher in the basal plate of SPTB placentas compared to those from term or elective preterm deliveries. In addition, in spontaneous term and preterm births, placental SLIT2 expression was correlated with variations in fetal growth. Knockdown of ROBO1 in trophoblast-derived HTR8/SVneo cells by siRNA indicated that it regulate expression of several pregnancy-specific beta-1-glycoprotein (PSG) genes and genes involved in inflammation. Our results show that the fetal SLIT2 variant and both SLIT2 and ROBO1 expression in placenta and trophoblast cells may be correlated with susceptibility to SPTB. SLIT2-ROBO1 signaling was linked with regulation of genes involved in inflammation, PSG genes, decidualization and fetal growth. We propose that this receptor-ligand couple is a component of the signaling network that promotes SPTB.

Ontology groups representing angiogenesis and blood vessels development are highly up-regulated during porcine oviductal epithelial cells long-term real-time proliferation – a primary cell culture approach

The morphological and biochemical modification of oviductal epithelial cells (OECs) belongs to the group of compound processes responsible for proper oocyte transport and successful fertilization. The cellular interactions between cumulus-oocyte complexes (COCs) and oviductal epithelial cells (OECs) are crucial for this unique mechanism. In the present study we have analyzed angiogenesis and blood vessel development processes at transcript levels. By employing microarrays, four ontological groups associated with these mechanisms have been described. Differentially expressed genes belonging to the “angiogenesis”, “blood circulation”, “blood vessel development” and “blood vessel morphogenesis” GO BP terms were investigated as a potential markers for the creation of new blood vessels in cells under in vitro primary culture conditions.

Human trophoblast invasion: new and unexpected routes and functions

Until recently, trophoblast invasion during human placentation was characterized by and restricted to invasion into uterine connective tissues and the uterine spiral arteries. The latter was explained to connect the arteries to the intervillous space of the placenta and to guarantee the blood supply of the mother to the placenta. Today, this picture has dramatically changed. Invasion of endoglandular trophoblast into uterine glands, already starting at the time of implantation, enables histiotrophic nutrition of the embryo prior to perfusion of the placenta with maternal blood. This is followed by invasion of endovenous trophoblasts into uterine veins to guarantee the drainage of fluids from the placenta back into the maternal circulation throughout pregnancy. In addition, invasion of endolymphatic trophoblasts into the lymph vessels of the uterus has been described. Only then, invasion of endoarterial trophoblasts into spiral arteries takes place, enabling hemotrophic nutrition of the fetus starting with the second trimester of pregnancy. This new knowledge paves the way to identify changes that may occur in pathological pregnancies, from tubal pregnancies to recurrent spontaneous abortions.

MicroRNA-218-5p Promotes Endovascular Trophoblast Differentiation and Spiral Artery Remodeling

Preeclampsia (PE) is the leading cause of maternal and neonatal morbidity and mortality. Defects in trophoblast invasion, differentiation of endovascular extravillous trophoblasts (enEVTs), and spiral artery remodeling are key factors in PE development. There are no markers clinically available to predict PE, leaving expedited delivery as the only effective therapy. Dysregulation of miRNA in clinical tissues and maternal circulation have opened a new avenue for biomarker discovery. In this study, we investigated the role of miR-218-5p in PE development. miR-218-5p was highly expressed in EVTs and significantly downregulated in PE placentas. Using first-trimester trophoblast cell lines and human placental explants, we found that miR-218-5p overexpression promoted, whereas anti-miR-218-5p suppressed, trophoblast invasion, EVT outgrowth, and enEVT differentiation. Furthermore, miR-218-5p accelerated spiral artery remodeling in a decidua-placenta co-culture. The effect of miR-218-5p was mediated by the suppression of transforming growth factor (TGF)-β2 signaling. Silencing of TGFB2 mimicked, whereas treatment with TGF-β2 partially reversed, the effects of miR-218-5p. Taken together, these findings demonstrate that miR-218-5p promotes trophoblast invasion and enEVT differentiation through a novel miR-218-5p-TGF-β2 pathway. This study elucidates the role of an miRNA in enEVT differentiation and spiral artery remodeling and suggests that downregulation of miR-218-5p contributes to PE development.

Alterted SLIT2/ROBO1 signalling is linked to impaired placentation of missed and threatened miscarriage in early pregnancy

AIMS

Two-thirds of early pregnancy failures present with reduced trophoblast invasion, and SLIT2/ROBO1 signalling is considered to play an important role in trophoblast function during pregnancy. We investigated SLIT2/ROBO1 signalling associated with missed and threatened miscarriage during early gestation.

METHODS AND RESULTS

Human placenta samples were collected from women with missed miscarriage (n = 25), threatened miscarriage (n = 22) and termination of pregnancy controls (n = 32). Corresponding decreases in beta human chorionic gonadotrophin (β-hCG) levels and shallow trophoblast invasion were observed in patients with missed and threatened miscarriage, immunohistological staining revealed abnormal Slit2 and Robo1, as well as E-cadherin and activating protein-2 alpha (AP-2α) expression in villi and extravillous trophoblasts, and the expression of these proteins were confirmed in villi and decidua of miscarriage material by Western blotting. Using HTR8/SVneo cells, blocking SLIT2/ROBO1 signalling promoted cell migration, proliferation and suppressed differentiation. Moreover, blocking SLIT2/ROBO1 signalling in HTR8/SVneo cells altered trophoblast differentiation-related and angiogenesis-related gene mRNA expression, which also occurred in the tissues of missed and threatened miscarriage.

CONCLUSIONS

SLIT2/ROBO1 signalling may regulate trophoblast differentiation and invasion causing restricting β-hCG production, shallow trophoblast invasion and inhibiting placental angiogenesis in missed and threatened miscarriage during the first trimester.