Genome-wide association study meta-analysis supports association between MUC1 and ectopic pregnancy

STUDY QUESTION

Can we identify genetic variants associated with ectopic pregnancy by undertaking the first genome-wide association study (GWAS) leveraging two large-scale biobank initiatives?

SUMMARY ANSWER

We identified two novel genome-wide significant associations with ectopic pregnancy, highlighting MUC1 (mucin 1) as the most plausible affected gene.

WHAT IS KNOWN ALREADY

Ectopic pregnancy is an important cause of maternal morbidity and mortality worldwide. Despite being a common early pregnancy complication, the genetic predisposition to this condition remains understudied and no large scale genetic studies have been performed so far.

STUDY DESIGN, SIZE, DURATION

A GWAS meta-analysis including 7070 women with ectopic pregnancy and 248 810 controls from Estonian Biobank and the FinnGen study.

PARTICIPANTS/MATERIALS, SETTING, METHODS

We identified ectopic pregnancy cases from national registers by ICD (International Classification of Disease) codes (ICD-10 O00), and all remaining women were considered controls. We carried out standard GWAS meta-analysis and additionally annotated GWAS signals, analysed co-localization with quantitative trait loci, estimated genetic correlations and identified associated phenotypes to characterize the genetic signals, as well as to analyse the genetic and phenotypic relationships with the condition.

MAIN RESULTS AND THE ROLE OF CHANCE

We identified two genome-wide significant loci on chromosomes 1 (rs4971091, P = 5.32×10-9) and 10 (rs11598956, P = 2.41×10-8) potentially associated with ectopic pregnancy. Follow-up analyses propose MUC1, which codes for an epithelial glycoprotein with an important role in barrier function, as the most likely candidate gene for the association on chromosome 1. We also characterize the phenotypic and genetic correlations with other phenotypes, identifying a genetic correlation with smoking and diseases of the (genito)urinary and gastrointestinal system, and phenotypic correlations with various reproductive health diagnoses, reflecting the previously known epidemiological associations.

LARGE SCALE DATA

The GWAS meta-analysis summary statistics are available from the GWAS Catalogue (GCST90272883).

LIMITATIONS, REASONS FOR CAUTION

The main limitation is that the findings are based on European-based ancestry populations, with limited data on other populations, and we only captured maternal genomes. Additionally, further larger meta-analysis or independent studies are needed to validate these findings.

WIDER IMPLICATIONS OF THE FINDINGS

This study encourages the use of large-scale genetic datasets to unravel genetic factors linked to ectopic pregnancy, which is difficult to study in experimental settings. Increased sample size might bring additional genetic factors associating with ectopic pregnancy and inform its heritability. Altogether, our results provide more insight into the biology of ectopic pregnancy and, accordingly, the biological processes governing embryo implantation.

STUDY FUNDING/COMPETING INTEREST(S)

N.P.G. was supported by MATER Marie Sklodowska-Curie which received funding from the European Union's Horizon 2020 research and innovation program under grant agreement No. 813707. This study was funded by European Union through the European Regional Development Fund Project No. 2014-2020.4.01.15-0012 GENTRANSMED. Computations were performed in the High-Performance Computing Center of University of Tartu. The authors declare no competing interests.

Decorin expression in tubal ectopic and intrauterine pregnancies

OBJECTIVE

Decorin is a leucine-rich proteoglycan, affects the proliferation, migration, and invasion of extravillous trophoblasts (EVTs). In this study, we aimed to determine the localization of decorin in the implantation site in human tubal ectopic pregnancy, to compare decorin expression levels in ectopic and intrauterine pregnancy, and to investigate the relationship between implantation depth of the tubal wall and expression levels of decorin.

METHODS

15 patients underwent salpingectomy for tubal ectopic pregnancy and 15 underwent curettage for voluntary interruption of pregnancy were included. All blocks were stained with decorin immunohistochemical staining. Trophoblastic cells of tubal Stage I-III and tubal epithelial and stromal cells were analyzed in terms of presence and intensity of decorin staining.

RESULTS

Decorin was expressed in both tubal and intrauterine trophoblasts, stroma, and surface epithelium during the first trimester of pregnancy. Decorin staining intensity was significantly lower in the villous cytotrophoblasts and syncytiotrophoblasts in tubal ectopic pregnancies, compared to intrauterine pregnancies (p = 0.001 for both). Decorin staining intensity also significantly lower in the extravillous cytotrophoblasts and syncytiotrophoblasts in the tubal ectopic pregnancies (p = 0.002 and p = 0.001, respectively). There was no significant difference in the staining intensity of the trophoblasts and surface epithelial between Stage II and Stage III tubal invasion; however, the decorin expression was lower in the stroma in Stage III (p = 0.094).

CONCLUSION

Decorin expression is significantly lower in trophoblastic cells of tubal ectopic pregnancies than the intrauterine pregnancies. Although it remains limited to explain the underlying cellular mechanisms, decorin seems to play a role in the development of tubal pregnancy.

Abnormally increased DNA methylation in chorionic tissue might play an important role in development of ectopic pregnancy

BACKGROUND

Human Ectopic Pregnancy (hEP) is the second most common cause of pregnancy-related deaths in the first trimester. Without timely detection, EPs can lead to an increased rate of infertility and an elevated risk for future tubal EPs. In addition, most studies in the field focus on the effect of the fallopian tube (maternal factors) and ignore epigenetic changes in genes and proteins of the embryo, which may also cause EPs. Therefore, the present study hypothesized that embryos also play an important role in the development of EP. The study also speculated that DNA methylation is associated with ectopic pregnancy. Consequently, the effects of DNA methylation on the occurrence and development of ectopic pregnancy were investigated. Moreover, genome-wide DNA methylation of chorionic tissue from ectopic and intrauterine pregnancies was detected using Illumina HumanMethylation450 arrays.

RESULTS

Forty-three hypermethylated genes involved in the regulation of adhesion as well as gene transcription and translation were identified. Furthermore, the PPI network showed that AMOTL1, SDR42E1, CAMTA1, PIP5K1C, KIAA1614, TSTD1 and DNER may play important roles in the occurrence and development of ectopic pregnancy. In addition, SDR42E1, CAMTA1 and TSTD1 displayed higher levels of methylation in ectopic pregnancy while PIP5K1C and DNER showed low degrees of methylation.

CONCLUSIONS

The study reveals that abnormal increase in methylation may be an early indicator or an inducer of ectopic pregnancy. In addition, AMOTL1, SDR42E1, CAMTA1, PIP5K1C, KIAA1614, TSTD1 and DNER might play important roles in the occurrence and development of ectopic pregnancy. However, the specific molecular mechanisms are still unclear and require further studies.

Uterine Scarring Leads to Adverse Pregnant Consequences by Impairing the Endometrium Response to Steroids

Uterine surgical scarring is an increasing risk factor for adverse pregnant consequences that threaten fetal-maternal health. The detailed molecular features of scar implantation remain largely unknown. We aim to study the pathologic features of uterine surgical scarring and the mechanisms of compromised pregnancy outcomes of scar implantation. We generated a mouse model of uterine surgical scarring with a uterine incision penetrating the myometrium to endometrium to examine the pathologic changes and transcriptome profiles of uterine scarring at various postsurgery (PS) time points, as well as features of the feto-maternal interface during scar implantation. We found that uterine surgical scar recovery was consistently poor at PS3 until PS90, as shown by a reduced number of endometrial glands, inhibition of myometrial smooth muscle cell growth but excessive collagen fiber deposition, and massive leukocyte infiltration. Transcriptome annotation indicated significant chronic inflammation at the scarring site. At the peri-implantation and postimplantation stages, abnormal expression of various steroid-responsive genes at the scarring site was in parallel with lumen epithelial cell hyperplasia, inappropriate luminal closure, and disorientation of the implanted embryo, restricted stromal cell proliferation, and defective decidualization. High embryonic lethality (around 70%) before E10.5 was observed, and the small amount of survival embryos at E10.5 exhibited restricted growth and aberrant placenta defects including overinvasion of trophoblast cells into the decidua and insufficient fetal blood vessel branching in the labyrinth. The findings indicate that chronic inflammation and compromised responses to steroids in uterine scar tissues are the pivotal molecular basis for adverse pregnancy consequences of scar implantation.

Prioritization of Susceptibility Genes for Ectopic Pregnancy by Gene Network Analysis

Ectopic pregnancy is a very dangerous complication of pregnancy, affecting 1%–2% of all reported pregnancies. Due to ethical constraints on human biopsies and the lack of suitable animal models, there has been little success in identifying functionally important genes in the pathogenesis of ectopic pregnancy. In the present study, we developed a random walk–based computational method named TM-rank to prioritize ectopic pregnancy–related genes based on text mining data and gene network information. Using a defined threshold value, we identified five top-ranked genes: VEGFA (vascular endothelial growth factor A), IL8 (interleukin 8), IL6 (interleukin 6), ESR1 (estrogen receptor 1) and EGFR (epidermal growth factor receptor). These genes are promising candidate genes that can serve as useful diagnostic biomarkers and therapeutic targets. Our approach represents a novel strategy for prioritizing disease susceptibility genes.

Pregnancy-associated microRNAs in plasma as potential molecular markers of ectopic pregnancy

OBJECTIVE

To investigate cell-free pregnancy-associated microRNAs as molecular markers for the diagnosis of ectopic pregnancy.

DESIGN

Laboratory study using human plasma samples.

SETTING

Research unit in a university hospital.

PATIENT(S)

Plasma samples from 18 women with ectopic pregnancies (EP group), 12 women with spontaneous abortion (SA group), and 26 normal women with singleton pregnancies (NP group).

INTERVENTION(S)

Total RNAs containing small RNA molecules extracted from 1.2 mL of plasma.

MAIN OUTCOME MEASURE(S)

Plasma concentrations of cell-free microRNAs measured by quantitative real-time reverse-transcriptase polymerase chain reaction.

RESULT(S)

Plasma concentrations of cell-free pregnancy-associated microRNAs (miR-323-3p, miR-515-3p, miR-517a, miR-517c, and miR-518b) and serum concentration of human chorionic gonadotropin (hCG) were confirmed to have statistically significantly different plasma or serum concentrations in women with EP, SA, or NP. There was no statistically significant difference in the plasma concentrations of cell-free miR-21 between the three groups. By correlation coefficient analysis, no relationship was detected between serum hCG levels and plasma cell-free miR-517c, miR-515-3p, miR-517a, miR-518b, miR-323-3p, or miR-21 levels. Plasma concentrations of cell-free miR-517a could distinguish EP/SA from NP, yielding an area under the curve of 0.9654 (95% confidence interval, 0.9172-1.0). Plasma concentrations of cell-free miR-323-3p could distinguish EP from SA, yielding an area under the curve of 0.7454 (95% confidence interval, 0.5558-0.9349).

CONCLUSION(S)

Cell-free pregnancy-associated microRNAs have potential as molecular markers of ectopic pregnancy.

Embryonic miRNA profiles of normal and ectopic pregnancies

Our objective was to investigate the miRNA profile of embryonic tissues in ectopic pregnancies (EPs) and controlled abortions (voluntary termination of pregnancy; VTOP). Twenty-three patients suffering from tubal EP and twenty-nine patients with a normal ongoing pregnancy scheduled for a VTOP were recruited. Embryonic tissue samples were analyzed by miRNA microarray and further validated by real time PCR. Microarray studies showed that four miRNAs were differentially downregulated (hsa-mir-196b, hsa-mir-30a, hsa-mir-873, and hsa-mir-337-3p) and three upregulated (hsa-mir-1288, hsa-mir-451, and hsa-mir-223) in EP compared to control tissue samples. Hsa-miR-196, hsa-miR-223, and hsa-miR-451 were further validated by real time PCR in a wider population of EP and control samples. We also performed a computational analysis to identify the gene targets and pathways which might be modulated by these three differentially expressed miRNAs. The most significant pathways found were the mucin type O-glycan biosynthesis and the ECM-receptor-interaction pathways. We also checked that the dysregulation of these three miRNAs was able to alter the expression of the gene targets in the embryonic tissues included in these pathways such as GALNT13 and ITGA2 genes. In conclusion, analysis of miRNAs in ectopic and eutopic embryonic tissues shows different expression patterns that could modify pathways which are critical for correct implantation, providing new insights into the understanding of ectopic implantation in humans.

Association study of vascular endothelial growth factor gene polymorphisms with ectopic pregnancy in Chinese women

OBJECTIVE

The purpose of this study is to evaluate potential associations between vascular endothelial growth factor (VEGF) gene polymorphisms and ectopic pregnancy (EP) in Chinese women.

MATERIALS AND METHODS

This was a case-control study wherein 192 women with a history of EP were compared to 210 post-menopausal controls with two pregnancies and no EP for the genotyping of VEGF polymorphisms. Genotyping of the VEGF gene polymorphisms at -460C/T, -1 154G/A, -2578C/A and +936C/T were performed by polymerase chain reaction-restriction fragment length polymorphism.

RESULTS

No significant differences were found in genotype and allele distributions of the -460C/T, +936C/T polymorphisms between cases and controls. Compared with the -1154G/G genotype, the -1154(A/A+G/A) genotype could significantly reduce the risk of developing EP. For the -2578C/A polymorphism, the A/A+C/A geno- type could significantly decrease the risk of developing EP, compared with the C/C genotype. The haplotype analysis suggested that the TAA (VEGF -460/-1154/-2578) and CAA haplotypes could significantly decrease the risk of developing EP compared with the haplotype of TGC.

CONCLUSION

The -1154A or -2578A alleles of VEGF gene could significantly decrease the risk of EP and might be po- tentially protective factors for EP development in Chinese women.

Variation in stability of endogenous reference genes in fallopian tubes and endometrium from healthy and ectopic pregnant women

RT-qPCR is commonly employed in gene expression studies in ectopic pregnancy. Most use RN18S1, β-actin or GAPDH as internal controls without validation of their suitability as reference genes. A systematic study of the suitability of endogenous reference genes for gene expression studies in ectopic pregnancy is lacking. The aims of this study were therefore to evaluate the stability of 12 reference genes and suggest those that are stable for use as internal control genes in fallopian tubes and endometrium from ectopic pregnancy and healthy non-pregnant controls. Analysis of the results showed that the genes consistently ranked in the top six by geNorm and NormFinder algorithms, were UBC, GAPDH, CYC1 and EIF4A2 (fallopian tubes) and UBC and ATP5B (endometrium). mRNA expression of NAPE-PLD as a test gene of interest varied between the groups depending on which of the 12 reference genes was used as internal controls. This study demonstrates that arbitrary selection of reference genes for normalisation in RT-qPCR studies in ectopic pregnancy without validation, risk producing inaccurate data and should therefore be discouraged.

Human fallopian tube epithelium constitutively expresses integrin endometrial receptivity markers: no evidence for a tubal implantation window

Understanding of ectopic implantation within the Fallopian tube (FT) is limited. In the human uterus, the putative 'window of implantation' in the mid-luteal phase of the menstrual cycle is accompanied by increased endometrial epithelial expression of the integrins α(1)β(1), α(4)β(1) and α(v)β(3) and its ligand osteopontin. Similar cyclical changes in FT integrin expression have been proposed to contribute to ectopic implantation, but supporting data are limited. In the current study, we present quantitative data on human FT transcription and translation of the integrin subunits α(1), α(4), α(V), β(1) and β(3) during the follicular and mid-luteal phases of the menstrual cycle, together with a supporting immuocytochemical analysis of their spatial distribution within the FT, and that of osteopontin. In contrast to previous studies, our data indicate that all five integrin receptivity markers are constitutively transcribed and translated in the FT, with no evidence for changes in their expression or distribution during the window of implantation in the mid-luteal phase of the cycle. Furthermore, we could find no evidence for cyclic redistribution of the integrin α(v)β(3) ligand osteopontin within the FT. Although we do not rule out the involvement of integrin endometrial receptivity markers in the establishment of ectopic pregnancy, our findings do not support their differential expression during a tubal implantation window.

Expression of the repulsive SLIT/ROBO pathway in the human endometrium and Fallopian tube

We investigated whether the repulsive SLIT/ROBO pathway is expressed in the endometrium and is negatively regulated during implantation. We also examined whether deficient expression in the Fallopian tube (FT) may predispose to ectopic pregnancy (EP). Endometrium (n = 21) and FT (n = 17) were collected across the menstrual cycle from fertile women with regular cycles. Decidualized endometrium (n = 6) was obtained from women undergoing termination, and FT (n = 6) was obtained from women with EP. SLIT/ROBO expression was quantified by reverse transcription-PCR and protein localized by immunohistochemistry. The regulation of SLIT/ROBO expression in vitro, by sex steroids and hCG, was assessed in endometrial (hTERT-EEpC) epithelial cells, and the effects of Chlamydia trachomatis infection and smoking were studied in oviductal (OE-E6/E7) epithelial cells. Endometrial SLIT3 was highest in the mid-secretory phase (P = 0.0003) and SLIT1,2 and ROBO1 showed a similar trend. ROBO2 was highest in proliferative phase (P = 0.027) and ROBO3,4 showed a similar trend. SLIT2,3 and ROBO1, 4 were lower in decidua compared with mid-secretory endometrium (P < 0.05). SLITs and ROBOs, excepting ROBO2, were expressed in FT but there were no differences across the cycle or in EP. SLIT/ROBO proteins were localized to endometrial and FT epithelium. Treatment of hTERT-EEpC with a combination of estradiol and medroxyprogesterone acetate inhibited ROBO1 expression (P < 0.01) but hCG had no effect. Acute treatment of OE-E6/E7 with smoking metabolite, cotinine, and C. trachomatis had no effect. These findings imply a regulated role for the endometrial SLIT/ROBO interaction during normal development and pregnancy but that it may not be important in the aetiology of EP.

[Correlation of a disintegrin and metalloprotease 12 level in maternal serum during the first trimester with pregnancy outcome]

OBJECTIVE

To explore the relationship between pregnant outcomes and the maternal serum level of a disintegrin and metalloprotease 12 (ADAM 12) in the first trimester.

METHODS

From July 2007 to January 2008, the serum levels of ADAM 12 of 511 women in their first trimester (6 - 13 gestational weeks), who attended the clinics at Peking Union Medical College Hospital, were tested by Time-Resolved Fluorescence Immunoassay (TR-FIA), and the results and pregnant outcomes were analyzed.

RESULTS

(1) The median levels of ADAM 12 at 6, 7, 8, 9, 10, 11, 12, 13 weeks of gestation were 14.63 microg/L, 35.08 microg/L, 88.90 microg/L, 186.51 microg/L, 370.62 microg/L, 537.71 microg/L, 632.55 microg/L, and 769.42 microg/L, respectively, showing a linear increase with the gestational age (r =0. 992, P < 0.01). (2) Among the 511 pregnancies, 427 were normal singleton term pregnancies and 84 had adverse perinatal outcomes. Twenty-seven miscarriages (5.3%, 27/511) and 5 ectopic pregnancies were reported and the Multiple of Medians (MOM) of them were 0.24 and 0.32, respectively, which was significantly lower than the normal singleton pregnancies (1.01, P < 0.05). However, the serum level of ADAM 12 in 5 women with placenta previa (MOM = 1.45) was significantly higher than the normal ones (P < 0.05). No significant correlation was found between the fetal birth weight and maternal serum level of ADAM 12 in the first trimester (r = -0.15, P < 0.05). (3) Thirteen cases with chromosomal abnormalities was identified out of 97 cases who received fetal karyotyping, including 3 Down's syndrome and 2 Turner syndrome, and the MOM of ADAM 12 in these 13 cases (0.34) was significantly different from those normal singleton pregnancies (P < 0.05). MoMs of ADAM 12 in 10 euchromosome aneupolyhaploids cases (0.29)were lower than the normal ones (P < 0.05).

CONCLUSION

The maternal serum level of ADAM 12 in the first-trimester is a potential marker for aneupolyhaploid screening and early fetal loss prediction, and is suggested to be tested at 9-12 gestational weeks as part of prenatal screening.

CB1 expression is attenuated in Fallopian tube and decidua of women with ectopic pregnancy

Background

Embryo retention in the Fallopian tube (FT) is thought to lead to ectopic pregnancy (EP), a considerable cause of morbidity. In mice, genetic/pharmacological silencing of cannabinoid receptor Cnr1, encoding CB1, causes retention of embryos in the oviduct. The role of the endocannabinoids in tubal implantation in humans is not known.

Methods and Findings

Timed FT biopsies (n = 18) were collected from women undergoing gynecological procedures for benign conditions. Endometrial biopsies and whole blood were collected from women undergoing surgery for EP (n = 11); management of miscarriage (n = 6), and termination of pregnancy (n = 8). Using RT-PCR and immunohistochemistry, CB1 mRNA and protein expression levels/patterns were examined in FT and endometrial biopsies. The distribution of two polymorphisms of CNR1 was examined by TaqMan analysis of genomic DNA from the whole blood samples. In normal FT, CB1 mRNA was higher in luteal compared to follicular-phase (p<0.05). CB1 protein was located in smooth muscle of the wall and of endothelial vessels, and luminal epithelium of FT. In FT from women with EP, CB1 mRNA expression was low. CB1 mRNA expression was also significantly lower (p<0.05) in endometrium of women with EP compared to intrauterine pregnancies (IUP). Although of 1359G/A (rs1049353) polymorphisms of CNR1 gene suggests differential distribution of genotypes between the small, available cohorts of women with EP and those with IUP, results were not statistically significant.

Conclusions

CB1 mRNA shows temporal variation in expression in human FT, likely regulated by progesterone. CB1 mRNA is expressed in low levels in both the FT and endometrium of women with EP. We propose that aberrant endocannabinoid-signaling in human FT leads to EP. Furthermore, our finding of reduced mRNA expression along with a possible association between polymorphism genotypes of the CNR1 gene and EP, suggests a possible genetic predisposition to EP that warrants replication in a larger sample pool.

Endometrial gene expression in early pregnancy: lessons from human ectopic pregnancy

Human endometrium undergoes modifications in preparation for embryonic implantation. This study investigated in vivo the endocrine effects of pregnancy on the endometrium, using the model of ectopic pregnancy. Endometrial biopsies from 9 subjects with ectopic pregnancy (Preg) were compared with 8 and 6 samples of mid and late secretory endometrium, respectively. After hybridizing with Affymetrix HGU133 Plus 2 chips, data were analyzed using GeneSpring GX and Ingenuity Pathways Analysis. From 54,675 genes, 3021 genes were significantly differentiated when mid-secretory endometrium was compared with the Preg (Volcano plot; P < .05, >or=2-fold change).The complement and coagulation cascade, phospholid degradation, glycosphingolipid biosynthesis (globoseries), retinol metabolism, antigen presentation pathway, glycosphingolipid biosynthesis, and O-glycan biosynthesis were main significant canonical pathways found in Preg samples. Validation was done with reverse transcriptase polymerase chain reaction. In conclusion, the ectopic embryo has a significant impact, by an endocrine mechanism, on endometrium, when compared with the window of implantation.

Fine-scale quantification of HCG beta gene transcription in human trophoblastic and non-malignant non-trophoblastic tissues

Human chorionic gonadotropin (HCG) is produced by syncytiotrophoblast of placenta. It delays the apoptosis of corpus luteum and functions in implantation. Its possible role in male reproduction has been raised. HCG beta subunit is encoded by CGB, CGB5, CGB7 and CGB8 genes located at 19q13.3 in a common genome cluster with beta subunit non-coding CGB1 and CGB2. We conducted a sensitive quantification and comparison of CGB gene expression in human trophoblastic (blastocysts, n = 6; normal/failed pregnancy, n = 51) and non-malignant non-trophoblastic tissues (15 different tissue types, samples n = 241), by real-time RT-PCR. We showed a wide transcriptional window of CGB genes in normal pregnancy, a significant reduction in recurrent miscarriages, and a high expression (especially CGB1/CGB2) in ectopic and molar pregnancies. Expression was several orders of magnitude lower in the non-placental tissues, with the highest CGB levels being seen in testis, prostate, thymus, skeletal muscle and lung samples. The contribution of CGB1/CGB2 to the summarized expression of six CGB genes was not proportional to their gene dosage: 1/1000 to 1/10,000. An interesting exception was the testis exhibiting a much higher CGB1/CGB2 to total CGB mRNA ratio of approximately one-third, corresponding to gene dosage. In conclusion, the expressional profile of CGB genes, activated already in blastocyst stage, is associated with the status of pregnancy. The presence of CGB transcripts in testes, and in particular CGB1/CGB2 transcripts, may indicate a role in male reproductive tract.

Increased expression of uteroglobin associated with tubal inflammation and ectopic pregnancy

OBJECTIVE

Evaluation of uteroglobin (UG) expression in the fallopian tube in different tubal diseases.

DESIGN

The UG was screened and quantified in samples of fallopian tubes from patients with salpingitis, hydrosalpinx, and ectopic pregnancy by exposing the UG with immunohistochemical techniques.

SETTING

University hospital and electron microscopy center.

PATIENT(S)

Women with pelvic inflammatory disease (PID) and complicated tubal ectopic pregnancy consulting for medical care.

INTERVENTION(S)

Salpingectomy.

MAIN OUTCOME MEASURE(S)

Tubal tissues were collected and examined using regular pathologic techniques. The UG immunoreactivity in the tubal epithelium was also assessed.

RESULT(S)

Fallopian tube epithelium displayed an increased UG expression in patients with PID and complicated tubal pregnancy compared with control patients.

CONCLUSION(S)

Uteroglobin is present in the human fallopian tube as a secretory protein and appears to be involved in immunosuppressive responses in the fallopian tube.

[Surgical management of ovarian ectopic pregnancy]

Ovarian pregnancies represent a small fraction of ectopic gestations. They are especially feared due to their life-threatening intraabdominal hemorrhage. Pre- and intraoperative diagnosis is difficult. Pathogenetically ovarian pregnancy arises from the retention of a fertilized ovum in the ovary. General guidelines for the medical management are missing. In this case report, we diagnosed a subacute ruptured ovarian pregnancy during surgery and performed a partial ovarectomy via operative laparoscopy. Other therapeutic options in managing ovarian ectopic pregnancy will be discussed.

Transcriptional characterizations of differences between eutopic and ectopic endometrium

Endometriosis, defined as the presence of endometrial glandular and stromal cells outside the uterine cavity, is a common gynecological disease with poorly understood pathogenesis. Using laser capture microdissection and a cDNA microarray with 9600 genes/expressed sequence tags (ESTs), we have conducted a comprehensive profiling of gene expression differences between the ectopic and eutopic endometrium taken from 12 women with endometriosis adjusted for menstrual phase and the location of the lesions. With dye-swapping and replicated arrays, we found 904 genes/ESTs that are differentially expressed. We validated the gene expression using real-time RT-PCR. We found that the expression patterns of these genes/ESTs correctly classified the 12 patients into ovarian and nonovarian endometriosis. We identified gene clusters that are location-specific. In addition, we identified several biological themes using Expression Analysis Systematic Explorer. Finally, we identified 79 pathways with over 100 genes with known functions, which include oxidative stress, focal adhesion, Wnt signaling, and MAPK signaling. The identification of these genes and their associated pathways provides new insight. Our findings will stimulate future investigations on molecular genetic mechanisms underlying the pathogenesis of endometriosis.

Comparative genomic hybridization of ectopic pregnancies that fail methotrexate therapy

Ectopic pregnancies that fail methotrexate therapy are predominantly euploid by comparative genomic hybridization (CGH). This feasibility study also confirms that formalin-fixed paraffin-embedded gestational tissue can successfully undergo CGH.

Interleukin-1 system messenger ribonucleic acid and protein expression in human fallopian tube may be associated with ectopic pregnancy

OBJECTIVE

To investigate the interleukin-1 (IL-1) system mRNA and protein expression in human fallopian tubes with ectopic pregnancies.

DESIGN

A controlled study.

SETTING

Clinical and academic research setting in a university medical center.

PATIENT(S)

Women undergoing salpingectomy for fallopian tube with ectopic pregnancy and women undergoing tubal ligation.

INTERVENTION(S)

Paired segments of human fallopian tubes containing an ectopic pregnancy and parafallopian tube segments adjacent to the ectopic pregnancy were collected from five women undergoing laparoscopic salpingectomy. Segments of fallopian tubes from four women undergoing tubal ligation were used as control tissues. Quantitative competitive polymerase chain reaction (QC-PCR) and immunohistochemistry were performed.

MAIN OUTCOME MEASURE(S)

The differences of IL-1 system mRNA and the ratio of IL-1beta to IL-1 receptor antagonist (IL-1ra) in both fallopian tubes with ectopic pregnancies and normal controls were analyzed.

RESULT(S)

A complete IL-1 system mRNA and protein expression was identified in both fallopian tubes with ectopic pregnancies and normal controls. As QC-PCR demonstrated, IL-1beta mRNA expression was decreased, and IL-1ra and IL-1 receptor type 1 were increased in fallopian tubes with ectopic pregnancies in comparison with normal control tubes. In para-ectopic tubes, IL-1 receptor type 1 mRNA was statistically significantly increased in comparison with normal controls. There was a lower ratio of IL-1beta to IL-1ra at mRNA in fallopian tubes with ectopic pregnancies.

CONCLUSION(S)

These results suggest that an inappropriate ratio of IL-1beta to IL-1ra and a higher expression of its receptor in fallopian tubes may possibly be implicated to the implantation of an ectopic pregnancy in the oviduct.

Detection of chromosome abnormalities by quantitative fluorescent PCR in ectopic pregnancies

OBJECTIVE

To evaluate the potential value of quantitative fluorescent polymerase chain reaction (QF-PCR) in the detection of chromosome abnormalities in ectopic pregnancies.

METHODS

Seventy chorionic villi samples of ectopic pregnancies were studied by QF-PCR. Primers for chromosomes 16, 21, X and Y in chorionic villi were evaluated. Fluorescence in situ hybridization (FISH) was performed when results of QF-PCR showed aneuploidy, in case of unexplicable QF-PCR peaks, and in 10 cases with normal QF-PCR results.

RESULTS

QF-PCR produced a result for chromosomes X and Y in 66 cases (94%), for chromosome 16 in 62 cases (89%) and for chromosome 21 in 55 cases (79%). Overall, QF-PCR produced a result for the chromosomes tested in 54 ectopic pregnancy cases (77%). Fifty-two of these results were normal disomic (96%) and two were abnormal, one trisomy 16 (2%) and one triploidy (2%). In 16 cases (23%) no definite QF-PCR results could be obtained for all chromosomes, 11 due to amplification failure, and 5 due to unexplicable QF-PCR peaks. In 10 cases with normal QF-PCR results, disomy was confirmed by FISH. The trisomy 16 was also confirmed by FISH. Furthermore, a result was obtained with FISH in 5 of the cases without definite QF-PCR results.

CONCLUSION

Although QF-PCR can establish the chromosomal status in ectopic pregnancies for chromosomes 16, 21, X and Y in the majority of cases, the technical failure rate is still considerable and does not improve results when compared to cytogenetic techniques.

Increased messenger RNA expression of vascular endothelial growth factor and its receptors in the implantation site of the human oviduct with ectopic gestation

OBJECTIVE

To compare the mRNA expression of vascular endothelial growth factor (VEGF) and its receptors (KDR and flt-1) in the implantation and nonimplantation sites of the human oviduct with ectopic gestation.

DESIGN

Prospective observational study.

SETTING

University-based Obstetrics and Gynecology Department.

PATIENT(S)

Ten women undergoing laparoscopic salpingectomy for tubal pregnancy.

INTERVENTION(S)

The mucosal layer was isolated from the implantation and nonimplantation sites of the oviduct tissue with ectopic gestation. Semiquantitative reverse transcriptase-polymerase chain reaction was performed.

MAIN OUTCOME MEASURE(S)

The differences in the mRNA expression of VEGF and its receptors between the implantation and nonimplantation sites of the oviduct tissue.

RESULT(S)

The mRNA expression of VEGF and its receptors, both KDR and flt-1, was significantly higher in the implantation site of the human oviduct with ectopic gestation compared with the nonimplantation site.

CONCLUSION(S)

The results suggest that VEGF may be the angiogenic factor responsible for the implantation and placentation of an ectopic pregnancy in the oviduct.

Leukemia inhibitory factor and homeobox a10 gene expression in an ectopic pregnancy model for implantation

OBJECTIVE

We investigated the expression of leukemia inhibitory factor and homeobox a10 in endometrium that was derived from patients with concurrent ectopic pregnancies compared with nonpregnant luteal phase endometrium from the same patients.

STUDY DESIGN

Endometrial biopsy specimens that were obtained from women (n=3) who underwent surgery for ectopic pregnancy were matched with biopsy specimens in a nonpregnant luteal phase from the same patients. Quantitative reverse transcription polymerase chain reaction for leukemia inhibitory factor and homeobox a10 was performed. Polymerase chain reaction products were assayed with laser detection of nanogram quantities of complementary deoxyribonucleic acid. Ratios of each implantation marker to glyceraldehyde-3-phosphate dehydrogenase as an internal standard were compared for quantification.

RESULTS

Leukemia inhibitory factor expression is increased in endometrium from ectopic pregnancy; homeobox a10 is increased in luteal phase endometrium.

CONCLUSION

Leukemia inhibitory factor appears to be regulated by human chorionic gonadotropin or other factors of pregnancy; homeobox a10 is regulated by ovarian steroids of the luteal phase.

HOXA10 gene expression in human fallopian tube and ectopic pregnancy

OBJECTIVE

The molecular mechanisms underlying ectopic implantation have not been well characterized. Here we investigate HOXA10 gene expression at the site of ectopic implantation as compared with the endometrium and with the normal fallopian tube.

STUDY DESIGN

Northern blot analysis was used to evaluate HOXA10 gene messenger RNA level in various segments of normal pregnant and nonpregnant human fallopian tube, ectopic pregnancy, and endometrium.

RESULTS

Normal human fallopian tube expressed minimal levels of HOXA10 gene messenger RNA in the nonpregnant state. A trend toward a greater expression of HOXA10 gene was observed in the normal fallopian tube during pregnancy, but the difference was not statistically significant (P =.075). HOXA10 gene messenger RNA expression was up-regulated significantly at the site of implantation in ectopic pregnancy (P <.001), and its expression approached that of the endometrium during normal pregnancy (P =.33).

CONCLUSION

HOXA10 gene expression is up-regulated at the ectopic implantation site in the fallopian tube, approaching that of the endometrium in normal intrauterine gestation. Inherently increased HOXA10 gene expression in the fallopian tube or dysregulation of HOXA10 gene expression by an abnormally implanting blastocyst may play a role in ectopic implantation.

Altered phenotype of HLA-G expressing trophoblast and decidual natural killer cells in pathological pregnancies

BACKGROUND

The interaction between decidual natural killer (NK) cells and alloantigens expressed on fetal trophoblast cells are thought to be essential for successful implantation and placentation. Consequently, a disturbed interaction during the first trimester of pregnancy might well lead to a subsequent pregnancy failure.

METHODS

We investigated the expression of HLA-G and NK cell markers in tissue sections from recurrent miscarriage (n = 9) and ectopic tubal pregnancies (n = 5), and two hysterectomy specimens of healthy pregnancy as well as decidual biopsies (n = 9) were used as controls.

RESULTS

We show in normal pregnancy not only a decrease, but also a morphological change in CD56+ NK cells upon interaction with HLA-G-expressing trophoblasts. The cells appear to be transitioning from a blast-like (activation) state into a state of apoptosis. The number of CD16+ NK cells was low. In contrast, in recurrent miscarriage tissue a sustained NK cell marker expression of both CD56 and CD16 was paralleled by a decreased expression of HLA-G. No morphological changes from the blast-like stage were apparent. Finally, in ectopic pregnancies HLA-G expression in the absence of decidual NK cells was associated with a disturbed trophoblast differentiation.

CONCLUSIONS

In pathological pregnancies we show an in-situ altered phenotype of trophoblast and NK cells.

Association of histologic features and cytogenetic abnormalities in ectopic pregnancies

OBJECTIVE

To evaluate the association between specific histologic features and cytogenetic abnormalities in ectopic pregnancies.

DESIGN

Blinded histologic analysis.

SETTING

University hospital.

PATIENT(S)

Fifty-four patients with ectopic pregnancy for whom successful karyotypes and sufficient histologic material were available.

INTERVENTION(S)

Histologic evaluation of chorionic villi from ectopic pregnancies was done by two pathologists who were unaware of the cytogenetic outcome. Seventeen histologic features were evaluated: villus size, villus contour, ghost villi, hydropic villi, trophoblastic hyperplasia, trophoblastic hypoplasia, syncytial knots, Hofbauer cells, blood vessels, trophoblastic lacunae, trophoblastic inclusions or cisterns, degeneration, fibrohyalinization, microcalcifications, and perivillous and intervillous fibrin deposits.

MAIN OUTCOME MEASURE(S)

The association between histopathologic features and cytogenetic outcome.

RESULT(S)

The presence of ghost villi and intervillous or perivillous fibrin was found to be associated with cytogenetic abnormalities. These features are associated with previous fetal cell death.

CONCLUSION(S)

This study does not support an association between specific histologic features of chorionic villi and cytogenetic abnormalities in ectopic pregnancies. The only histologic features that were associated with cytogenetic abnormalities (i.e., ghost villi and intervillous and perivillous fibrin) are merely a result of previous fetal cell death.

Chromosomal abnormalities in ectopic pregnancy chorionic villi

OBJECTIVE

To evaluate the incidence of chromosomal abnormalities in ectopic pregnancy chorionic villi.

METHODS

A prospective study of patients with the diagnosis of ectopic pregnancy was conducted, with chorionic villi obtained at the time of surgical therapy cultured and analyzed for karyotype. Review of the patient's medical record and ultrasound evaluation was then completed and findings correlated with karyotype results.

RESULTS

Twenty-two patients undergoing surgery for the diagnosis of ectopic pregnancy yielded chorionic villi for culture. Successful culture was performed in 21 patients, with 3 (14%) revealing abnormal karyotypes. Review of the medical record showed ultrasound results consistent with fetal development or a gestational sac in 15 of 18 patients with normal chromosomal analysis. Three of 6 patients without fetal development yielded abnormal chromosomal findings.

CONCLUSION

Our results confirm that a high degree of success can be achieved in the karyotype analysis of ectopic pregnancy chorionic villi and that these conceptuses have a rate of abnormality similar to that reported for intrauterine gestations. Our data further suggest that when a gestational sac or fetal pole is identified by ultrasound, there is usually a normal karyotype.

Allelic polymorphism and chromosomal localization of the human oviductin gene (MUC9)

OBJECTIVE

To determine if the gene coding for human oviductin (the estrogen-dependent, oviduct-specific glycoprotein with an affinity for the zona pellucida) shows length polymorphism in the region of tandem repeats. To determine the frequencies of the length alleles in health and disease.

DESIGN

Descriptive fundamental and clinical studies.

SETTING

Fertility clinic and research center, university teaching hospital.

PATIENT(S)

Fertile women, women with a history of ectopic pregnancy or tubal disease, and women with stage I or II endometriosis.

INTERVENTION(S)

Blood samples were drawn for DNA analysis.

MAIN OUTCOME MEASURE(S)

Length and sequence of the region of tandem repeats.

RESULT(S)

Four different length alleles of the human oviductin gene were identified. Their relative frequencies in pathologic cases were not statistically significant compared with those found in normal fertile women. The human genome contains a single copy of the oviductin gene located on chromosome 1p13.

CONCLUSION(S)

The human oviductin gene codes for a glycoprotein that shares the characteristics of epithelial mucins. Because eight epithelial mucin genes have been identified so far, we therefore propose to name this gene MUC9. The biologic function of the protein is likely to include protection of the early embryo and of the fallopian tube itself.

[Spontaneous abortion: cytogenetic study of 609 cases]

Chromosomal abnormalities are the most frequent cause of first trimester spontaneous abortions (SA). During the period September 1989 through May 1996 we have cytogenetically studied 640 embryonic tissue samples obtained from cases of SA. Of these, 609 samples (95.1%) were successfully karyotyped. An abnormal karyotype was observed in 388 cases (63.7%). The sex ratio (XY/XX) was 1.03. There was no difference of this ratio between cytogenetically normal and abnormal embryos. The most frequent abnormalities detected were autosomal trisomies (239/388 [61.6%]) followed by triploidy (62 cases, 16%), monosomies (41 cases, 10.6%) and tetraploidy (17 cases, 4.4%). The single most common anomaly observed was trisomy 16 (73 cases, 18.8%). The frequency of trisomies, with the exception trisomy 16, was related with advanced maternal age.

Cytogenetic characteristics of ectopic pregnancy

During a 12 month period, tissue was collected from 30 surgically managed patients presenting with vital ectopic pregnancies. Chorionic villi of the removed tissue were successfully karyotyped by (semi-) direct chromosome technique in 22 cases. Only one abnormal chromosomal complement, a triploidy (69,XXX) was found. As controls, 10 cases of intrauterine pregnancies were investigated, all showing a normal karyotype. These findings do not suggest an important role for chromosome abnormalities in the aetiology of vital ectopic pregnancies.

DNA ploidy of ectopic pregnancy and first trimester spontaneous abortion investigated by flow cytometry

BACKGROUND

To compare the success rate of DNA flow cytometry in determining the DNA ploidy status in ectopic pregnancy and first trimester spontaneous abortion.

METHODS

Thirteen women with ectopic pregnancy (Group I) and 17 women with first trimester spontaneous abortion (Group II) were included into this study. DNA flow cytometric analysis was performed on all specimens. Aneuploidy was classified according to DNA index. The first trimester spontaneous abortions were also karyotyped after long-term culture of chronic villi. Student-t test and Fisher's exact test were used in statistical comparisons.

RESULTS

DNA aneuploidy was found in five women with ectopic pregnancy (38.5%) versus in 12 women with first trimester spontaneous abortion (70.6%), and it was comparable. A triploidy and a tetraploidy were detected in group I. Six tubal ectopic pregnancies were unruptured at laparatomy and four of them had aneuploid DNA content.

CONCLUSIONS

We believed that DNA flow cytometry was successful in determining the ploidy status of ectopic pregnancy and first trimester spontaneous abortion. In addition, it was interesting that ectopic pregnancies with aneuploid DNA content tended to be unruptured. However, this suggestion needs to be confirmed by further studies with larger numbers of cases.

Cytogenetic study employing chorionic villi in ectopic pregnancy

Maternal factors such as salpingitis and peritubal adhesion are known to be associated with ectopic pregnancy; however, a few studies have considered the chromosomal complements of ectopic conceptuses. We studied 16 ectopic conceptuses obtained by surgical resection. The karyotyping of chorionic villi was performed using direct and culture technique. Among 16 studied cases, 14 cases showed normal karyotype (nine with 46, XY; five with 46, XX). One case showed trisomy 16(47, XY, + 16) and another showed variation from normal chromosomal complement (46, XY, 14s+), resulting in 6.3% incidence of the structural abnormalities of the chromosome. On the basis of our study, we determined the possibility of chorionic villi karyotyping in ectopic pregnancy. This ectopic conceptuses are no more likely to show chromosomal abnormalities than in utero conceptuses of comparable gestational age. Therefore, maternal factors such as salpingitis and peritubal adhesion are the most likely explanations for ectopic pregnancy.

DNA aneuploidy in ectopic pregnancy and spontaneous abortions

The nuclear DNA content of 55 ectopic tubal pregnancies was studied by flow cytometry from paraffin embedded tissue blocks. An abnormal amount of DNA content was found in 24% of the cases. This was a significantly higher percentage than encountered in 92 spontaneous abortions studied by the same method in the same population (8%, P = 0.01). The result indicates that, in addition to the maternal factors, abnormal embryogenesis with grave chromosomal aberrations may play a major role in the etiology of ectopic pregnancy.

Rapid karyotyping in ectopic pregnancies

The aim of this study was to determine the feasibility of karyotyping ectopic Fallopian tube pregnancies utilizing dividing cytotrophoblast cells. Villi from 78 ectopic conceptuses were processed by the direct chromosome technique and cytogenetic diagnosis was successful in 60 cases (76.9 per cent). The amount of villi obtained, as well as villus morphology, was correlated with cytogenetic success rate. Histological examination of the Fallopian tube was also carried out. A total of 47 cases were chromosomally abnormal (78.3 per cent), which is the highest frequency of cytogenetic abnormalities reported to date.

Abnormal embryogenesis in the etiology of ectopic pregnancy

Flow cytometric measurements of DNA using paraffin-embedded retrospective material were performed on 42 samples of ectopic conceptuses to see whether there were any aberrations from normal DNA. It was found that DNA aneuploidy was associated with tubal implantation in 14 (33%) cases. The range of DNA indices of the DNA aneuploid peaks was from 1.14 to 2.17. Near-diploid karyotype changes were seen in 8 (19%) cases. Six cases were found to be tetraploid. In 18 abortions with known cytogenetic status, all 3 cytogenetically normal cases showed DNA diploidy in flow cytometry. It was also found that 3 out of 10 cases of trisomy 21 were DNA aneuploid. Flow cytometric DNA reflects only chromosomal changes where a significant number of cells have either lost or acquired several chromosomes. DNA aneuploidy of ectopic pregnancies suggests a grave chromosomal aberration in one third of the cases. Abnormal embryogenesis may contribute significantly to the occurrence of ectopic implantation.

[The role of chromosomes in the aetiology of human abortion]

Of 27 specimens of abortus tissue from first-trimester spontaneous abortions investigated, 26% had chromosome abnormalities. In contrast, the investigation showed that the incidence of chromosome abnormalities in 36 midtrimester cases was only 2,8%. Two of 19 ectopic pregnancies had abnormal chromosome complements.