Chorionic villous vascularization related to phenotype and genotype in first trimester miscarriages in a recurrent pregnancy loss cohort

Genetic variation in placental insufficiency: What have we learned over time?

Genetic variation shapes placental development and function, which has long been known to impact fetal growth and pregnancy outcomes such as miscarriage or maternal pre-eclampsia. Early epidemiology studies provided evidence of a strong heritable component to these conditions with both maternal and fetal-placental genetic factors contributing. Subsequently, cytogenetic studies of the placenta and the advent of prenatal diagnosis to detect chromosomal abnormalities provided direct evidence of the importance of spontaneously arising genetic variation in the placenta, such as trisomy and uniparental disomy, drawing inferences that remain relevant to this day. Candidate gene approaches highlighted the role of genetic variation in genes influencing immune interactions at the maternal-fetal interface and angiogenic factors. More recently, the emergence of molecular techniques and in particular high-throughput technologies such as Single-Nucleotide Polymorphism (SNP) arrays, has facilitated the discovery of copy number variation and study of SNP associations with conditions related to placental insufficiency. This review integrates past and more recent knowledge to provide important insights into the role of placental function on fetal and perinatal health, as well as into the mechanisms leading to genetic variation during development.

Study on the correlation between the ultrasound phenotype and copy number variation of abnormal embryo in spontaneous abortion

OBJECTIVE

This study aimed to explore the correlation between the ultrasound phenotype and copy number variation (CNV) of abnormal embryos in spontaneous abortion by investigating the abnormal chromosome copy number of embryos at different developmental stages in early spontaneous abortion.

METHODS

A total of 539 patients who had early spontaneous abortion in our hospital between 2015 and 2019 were divided into seven groups according to the phenotype of abnormal embryonic development during pregnancy, and the embryonic tissues of the patients were subjected by single nucleotide polymorphism (SNP) microarray.

RESULTS

Among 377 cases with abnormal CNV, 295 (78.25%) cases had chromosome trisomy, and 28 (7.43%) cases had a combination of more than two chromosomes. Triploidy, tetraploidy, chromosome microdeletion/duplication, uniparental disomy, and monosomy 45,X were found in 32 (8.48%), five (1.32%), 31 (8.22%), four (1.02%), and eight (2.12%) cases, respectively. Two (0.53%) cases had autosomal chromosome 21 monosomy. Normal karyotype had the highest proportion in the empty sac group; trisomy 16 accounted for the bulk of chromosomes in the normal yolk sac group, complex triploidy occupied the most part in the abnormal yolk sac group, and no remarkable difference in chromosomal abnormality proportion was found between the normal and abnormal yolk sac groups; the most frequent chromosomal anomaly in a group of germ without cardiac activity and germ<5 mm was trisomy 16; triploidy was the most common in the group with 5 mm ≤ germ ≤ 15 mm, whereas the main distribution of chromosome karyotype was normal, followed by trisomy 13 in a group with germ>15 mm.

CONCLUSION

Abnormal embryos with different ultrasound phenotypes in early spontaneous abortion have various CNV types and characteristic distribution. Thus, ultrasound combined with SNP array can provide a basis for the etiological analysis of embryos in spontaneous abortion.

Expression of the Carbohydrate Lewis Antigen, Sialyl Lewis A, Sialyl Lewis X, Lewis X, and Lewis Y in the Placental Villi of Patients With Unexplained Miscarriages

Background

Lewis antigens such as Sialyl Lewis A (sLeA), Sialyl Lewis X (sLeX), Lewis X (LeX), and Lewis Y (LeY) are a class of carbohydrate molecules that are known to mediate adhesion between tumor cells and endothelium by interacting with its selectin ligands. However, their potential role in miscarriage remains enigmatic. This study aims to analyze the expression pattern of sLeA, sLeX, LeX, and LeY in the placental villi tissue of patients with a medical history of unexplained miscarriages.

Methods

Paraffin-embedded slides originating from placental tissue were collected from patients experiencing a miscarriage early in their pregnancy (6–13 weeks). Tissues collected from spontaneous (n = 20) and recurrent (n = 15) miscarriages were analyzed using immunohistochemical and immunofluorescent staining. Specimens obtained from legally terminated normal pregnancies were considered as control group (n = 18). Assessment of villous vessel density was performed in another cohort (n = 10 each group) of gestation ages-paired placenta tissue. Protein expression was evaluated with Immunoreactive Score (IRS). Statistical analysis was performed by using Graphpad Prism 8.

Results

Expression of sLeA, sLeX, LeX, and LeY in the syncytiotrophoblast was significantly upregulated in the control group compared with spontaneous and recurrent miscarriage groups. However, no prominent differences between spontaneous and recurrent miscarriage groups were identified. Potential key modulators ST3GAL6 and NEU1 were found to be significantly downregulated in the recurrent miscarriage group and upregulated in the spontaneous group, respectively. Interestingly, LeX and LeY expression was also detected in the endothelial cells of villous vessels in the control group but no significant expression in miscarriage groups. Furthermore, assessment of villous vessel density using CD31 found significantly diminished vessels in all size groups of villi (small villi <200 µm, P = 0.0371; middle villi between 200 and 400 µm, P = 0.0010 and large villi >400 µm, P = 0.0003). Immunofluorescent double staining also indicated the co-localization of LeX/Y and CD31.

Conclusions

The expression of four mentioned carbohydrate Lewis antigens and their potential modulators, ST3GAL6 and NEU1, in the placenta of patients with miscarriages was significantly different from the normal pregnancy. For the first time, their expression pattern in the placenta was illustrated, which might shed light on a novel understanding of Lewis antigens’ role in the pathogenesis of miscarriages.

Macroscopic and microscopic morphology of first trimester miscarriage and subsequent pregnancy outcome - An exploratory study

INTRODUCTION

Reduced chorionic villous vascularization is associated with first trimester miscarriage and second trimester fetal loss. Differences in villous vascularization have been observed in combination with complications in the third trimester of pregnancy. The aim of this study was to investigate whether abnormal morphology and reduced chorionic villous vascularization in first trimester miscarriages are associated with an increased risk on adverse outcome and/or pregnancy complications in subsequent pregnancy. Secondly, to assess the influence of these parameters on the length of the interpregnancy interval and infertility.

METHODS

In a retrospective cohort study 134 consecutive women who underwent dilatation and curettage for a miscarriage were included. The degree of chorionic villous vascularization in miscarriage tissue was determined by a pathologist. Ultrasound details of these miscarriages and clinical data on the subsequent pregnancy of these women were obtained.

RESULTS

Neither reduced vascularization nor early embryonic arrest in first trimester miscarriages are associated with an increased risk of a subsequent miscarriage or adverse obstetric and perinatal outcome of subsequent pregnancy. Abnormal morphology of the first trimester miscarriage did not influence the time to subsequent pregnancy. A shorter mean interpregnancy interval between miscarriages was observed after miscarriages with reduced chorionic villous vascularization (5.5 vs. 10.7 months; p = 0.051), showing a trend towards an association.

DISCUSSION

Chorionic villous vascularization and morphology have no influence on subsequent pregnancy outcome. Therefore it remains unknown what aspects of miscarriage are causing the increased risk on subsequent miscarriage and complications in the third trimester of the subsequent pregnancy.

High mobility group box 1 protein polymorphism affects susceptibility to recurrent pregnancy loss by up-regulating gene expression in chorionic villi

PURPOSE

Inflammation in chorionic villi is involved in the development of recurrent pregnancy loss (RPL). High mobility group box 1 protein (HMGB1) plays critical roles in inflammation and expression of the protein can be found in chorionic villi. The purpose of the study was to investigate the association between HMGB1 genetic polymorphisms and susceptibility to RPL and to examine the mechanism underlying this correlation.

METHODS

Two HMGB1 polymorphisms, rs2249825C/G and rs1412125T/C, were examined in 112 RPL patients and 118 healthy controls by the polymerase chain reaction-restriction fragment length polymorphism assay.

RESULTS

Percentage of rs2249825GG was significantly increased in patients than in controls (Odd ratio [OR] =2.33, 95 % confidence interval [CI]: 1.18-4.58, P = 0.013). Also, prevalence of rs2249825G allele was significantly higher in RPL cases (OR = 1.77, 95 % CI: 1.20-2.62, P = 0.004). Function analysis of rs2249825C/G revealed that the polymorphism did not affect serum level of HMGB1. Interestingly, we found significantly increased level of HMGB1 in chorionic villi from RPL patients. Moreover, patients with rs2249825GG genotype presented significantly elevated level of HMGB1 in chorionic villi compared to those with CG or CC genotypes.

CONCLUSIONS

These results suggest that HMGB1 rs2249825C/G polymorphism is associated with increased risk of RPL and can elevate gene expression in chorionic villi.

Recurrent pregnancy losses and gestational age are closely related: an observational cohort study on 759 pregnancy losses

To assess the accurate dating of the cessation of pregnancy in patients with recurrent pregnancy loss (RPL) and to evaluate the incidence and recurrence rate of pregnancy losses in similar gestational age. In a retrospective cohort study, couples with history of RPL and availability of precise documentation regarding previous pregnancy losses were included. The vast majority of losses occurred within the first trimester. In patients experiencing more than 2 miscarriages in the same gestational stage, a tendency for recurrent losses around the same period of gestation was observed. Overall, the probability of losses at different gestational stages goes down with increasing number of miscarriages at the same stage. The study supports the need to ascertain data regarding the timing of pregnancy loss as accurately as possible for prognosis of future pregnancies and management of couples. A classification for unexplained RPL based on gestational age of miscarriages could help researchers to better investigate RPL.