Ovarian follicular function is not altered by SARS-CoV-2 infection or BNT162b2 mRNA COVID-19 vaccination.

STUDY QUESTION: Does the immune response to coronavirus disease 2019 (COVID-19) infection or the BNT162b2 mRNA vaccine involve the ovarian follicle, and does it affect its function? SUMMARY ANSWER: We were able to demonstrate anti-severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) IgG in follicular fluid (FF) from both infected and vaccinated IVF patients, with no evidence for compromised follicular function. WHAT IS KNOWN ALREADY: No research data are available yet. STUDY DESIGN, SIZE, DURATION: This is a cohort study, composed of 32 consecutive IVF patients, either infected with COVID-19, vaccinated or non-exposed, conducted between 1 February and 10 March 2021 in a single university hospital-based IVF clinic. PARTICIPANTS/MATERIALS, SETTING, METHODS: A consecutive sample of female consenting patients undergoing oocyte retrieval was recruited and assigned to one of the three study groups: recovering from confirmed COVID-19 (n = 9); vaccinated (n = 9); and uninfected, non-vaccinated controls (n = 14). Serum and FF samples were taken and analyzed for anti-COVID IgG as well as estrogen, progesterone and heparan sulfate proteoglycan 2 concentration, as well as the number and maturity of aspirated oocytes and day of trigger estrogen and progesterone measurements. Main outcome measures were follicular function, including steroidogenesis, follicular response to the LH/hCG trigger, and oocyte quality biomarkers. MAIN RESULTS AND THE ROLE OF CHANCE: Both COVID-19 and the vaccine elicited anti-COVID IgG antibodies that were detected in the FF at levels proportional to the IgG serum concentration. No differences between the three groups were detected in any of the surrogate parameters for ovarian follicle quality. LIMITATIONS, REASONS FOR CAUTION: This is a small study, comprising a mixed fertile and infertile population, and its conclusions should be supported and validated by larger studies. WIDER IMPLICATIONS OF THE FINDINGS: This is the first study to examine the impact of SARS-Cov-2 infection and COVID-19 vaccination on ovarian function and these early findings suggest no measurable detrimental effect on function of the ovarian follicle. STUDY FUNDING/COMPETING INTEREST(S): The study was funded out of an internal budget. There are no conflicts of interest for any of the authors. TRIAL REGISTRATION NUMBER: CinicalTrials.gov registry number NCT04822012.

Triple paternal contribution to a normal/complete molar chimeric singleton placenta.

A comprehensive study of unusual cases of placental pathology may provide insight into mechanisms of normal human fertilization and early embryonic development by examining the exception to the rule. A gravida three para two 39-year-old woman was monitored by ultrasound from 16 weeks of gestation for cystic placenta. A female newborn was born at 36 weeks gestation. Pathologic examination of the partially cystic placenta revealed a singleton placenta comprised of 2/3 normal placenta and 1/3 complete hydatidiform mole, largely degenerated. Immunostaining for p57 was negative in stromal cells of the molar villi. Chromogenic in-situ hybridization revealed diploidy in both normal and molar parts. A total of 16 microsatellites were studied by short tandem repeat analysis, 11 of which were informative. The analysis revealed bipaternal molar tissue of dispermic origin. The paternal monospermic contribution to the normal part was different from that in the molar part, thus resulting in tripaternal contribution to the conceptus. A chimera is a single organism composed of two or more different populations of genetically distinct cells that originated from different zygotes (tetragametic) whereas mosaic is a mixture of two cell lines in one organism originating from one zygote. The possible mechanisms leading to the formation of chimeric/mosaic placenta in our case (one of the components being complete hydatidiform mole), including twinning, fusion at an early embryonic stage and diploidization of triploids, are discussed.

United we stand not dividing: the syncytiotrophoblast and cell senescence.

The multinucleate syncytiotrophoblast of the human placenta is responsible for transport functions between maternal and fetal blood supplies and is a major site of protein synthesis and steroid production. It is formed by cell fusion of the underlying cytotrophoblast cells. The nuclei of the multinucleate syncytiotrophoblast are non-mitotic yet the mechanism of cell cycle arrest in the syncytiotrophoblast is not known. The recent publication by the group of Krizhanovsky (2013), demonstrates that cell fusion induces cell senescence. The work reported the exciting finding that term placenta syncytiotrophoblast displays markers associated with cellular senescence. Cellular senescence is perhaps best known as a component of aging, a response to stress and an important factor in preventing tumor cell growth. The aforementioned study suggests myriad avenues of investigation in placental biology with intriguing possibilities to furthering our understanding of placental development and aging, health of pregnancy and placental pathologies having their origin in placental stress.

Expression profiling of autophagy associated genes in placentas of preeclampsia.

Autophagy, a mechanism of cell survival during times of stress, may be active in normal placental maintenance, cushioning the fetus from strain during fluctuations in nutrient availability. Moreover, in cases of placental insufficiency, often present in preeclampsia, autophagy may be defective. We used published microarray datasets to analyze differential expression of autophagy pathway genes. No statistically significant difference in autophagy associated gene expression was found in preeclamptic vs. normal placenta samples. Thus although preeclampsia displays many of the features suggestive of altered autophagy, impaired placental autophagy as a cause of preeclampsia is not supported by whole placental tissue differential expression profiling.

Human trophectoderm apposition is regulated by interferon γ-induced protein 10 (IP-10) during early implantation.

INTRODUCTION: The first step in human implantation is the attraction of the blastocyst to the endometrium. We aimed to study attraction of the human blastocyst to the endometrium, and how this process is accomplished by chemokines secreted by the endometrium. MATERIALS AND METHODS: Blastocyst trophectoderm cells and other trophoblast lineage cells were subjected to attraction assays by IP-10 and other chemokines using transwell migration and chemotaxis assays. Chemokine expression and secretion were investigated using immunohistochemistry, ELISA, FACS analysis, and RT-PCR on material from flushing of the uterine cavity in endometrial biopsies. Chemokine receptor expression by blastocyst trophectoderm following PGD biopsy, trophectoderm derived from hES, placental villi, and other trophoblast lineage cells were characterized by the same methods. RESULTS: IP-10 dramatically attracted trophectoderm derived from hES cells and other lineages by interaction with CXCR3 chemokine receptors, as shown by both chemotaxis and transwell migration. High levels of IP-10 were detected throughout the menstrual cycle at flushing of the uterine cavity. Immunohistochemistry, FACS analysis, and RT-PCR of endometrial biopsy detected IP-10 in glandular and stromal cells of the endometrium. High levels of IP-10 were detected in condition medium of the endometrial stromal and glandular cells. Of all of the chemokine/chemokine receptor combinations examined, the IP-10/CXCR3 interaction was the only cytokine that was significantly elevated. DISCUSSION: While they await the wandering blastocyst, IP-10 is produced by many cells of the endometrium, but not by endometrial natural killer cells. CONCLUSION: Endometrial IP-10 may specifically attract human blastocyst trophectoderm cells early in implantation.

Human placental Hofbauer cells express sprouty proteins: a possible modulating mechanism of villous branching.

The development of the chorionic villous tree into a complex and organized ramified tubular network can be termed branching morphogenesis. Studying the molecular mechanisms involved in this process may contribute to the understanding of pregnancy complications such as preeclampsia. Sprouty (Spry) proteins are important regulators of branching morphogenesis and growth factor signaling. We analyzed the expression of Spry genes in human placenta. RT-PCR and immunohistochemistry were employed to detect placental Spry expression. Quantitative RT-PCR was used to assess the effect of FGF and reduced oxygen fraction on Spry gene expression. Spry 1, 2 and 3 expression was observed in placental tissue from all three trimesters. Our results reveal for the first time that Spry proteins are localized in the stroma of the chorionic villi, adjacent to cytotrophoblasts in areas of villous sprouting. Immunofluorescent double staining with anti-Spry and anti-CD68 confirmed that placental macrophages (Hofbauer cells) express Spry. Reduced oxygen fraction, FGF-4 and FGF-10 stimulated Spry-2 expression. Hofbauer cells also expressed c-Cbl, a protein that interacts with Spry. Placental expression of Spry and c-Cbl implies an important role for Hofbauer cells in placental development, possibly through a mesenchymal-epithelial interaction with trophoblasts. Regulation of Spry-2 expression by FGF-4 and FGF-10 suggests an orchestrated regulatory system that modulates villous branching.

Eph and ephrin expression in normal placental development and preeclampsia.

Eph receptors and their ephrin ligands play a fundamental role in embryogenesis. Their functions include cell targeting and angiogenesis. In placental development, trophoblasts migrate and invade maternal tissue and spiral arteries, where they play a role in both anchoring the placenta to the uterus and increasing blood flow to the developing fetus (interstitial and endovascular invasions). We investigated the cellular distribution and expression patterns of representative Eph and ephrin RNA and protein in an effort to identify the molecules involved in trophoblast migration during normal placental development and placental pathologies. We found ephrin-A1 expressed exclusively in the invasive extravillous trophoblast (EVT) cell lineage. We therefore proceeded to investigate ephrin-A1 in placental pathologies with defects in EVT invasion. In preeclampsia, where trophoblast invasion is shallow, we observed ephrin-A1 expression similar to normal placenta. Furthermore, in initial experiments on the deeply invading trophoblasts of placenta accreta, which lacks decidua, ephrin-A1 is found to be expressed highly in extravillous trophoblasts that have invaded the myometrium. In addition, we found the prototype ephrin-A1 receptor, EphA2, localized in several placental cell types. EphB4 and ephrin-B2 molecules, which have specific expression patterns during artery and vein development, respectively, were also expressed in the placenta. The cell specific distribution of ephrin-A1 suggests that it may play a role in targeting and migration of trophoblasts, and in the vascular remodeling induced by the invading extravillous trophoblasts. Failure of ephrin-A1 expression is unlikely to be the primary cause in defective migration of trophoblasts observed in preeclampsia. Specific roles for other Eph and ephrin proteins remain to be investigated.

Vascular endothelial growth factor, epidermal growth factor and fibroblast growth factor-4 and -10 stimulate trophoblast plasminogen activator system and metalloproteinase-9.

Trophoblast invasion, accompanied by degradation of extracellular matrix, is crucial to normal pregnancy development, whereas shallow placental invasion and implantation likely plays a role in the subsequent development of pre-eclampsia. The growth factors vascular endothelial growth factor (VEGF), epidermal growth factor (EGF) and fibroblast growth factor (FGF) are placental growth factors that activate degradation of extracellular matrix. We determined the effect of VEGF, EGF, FGF-2, FGF-4 and FGF-10 on the plasminogen activator system of first trimester cytotrophoblasts cultured in vitro. We studied the activity of urokinase plasminogen activator (uPA), its inhibitor plasminogen activator inhibitor-1 (PAI-1), and 92 kDa gelatinase-B (matrix metalloproteinase-9, MMP-9), using protein gel and reversed gel zymography. The expression pattern of FGF-4 and FGF-10 in human placental sections was determined by immunohistochemistry. FGF-4 was expressed in first trimester villi stroma, primarily in endothelial cells. FGF-10 expression was localized to first trimester extravillous trophoblasts. VEGF, EGF, FGF-4 and FGF-10, but not FGF-2, stimulate the activity of trophoblast uPA, PAI-1 and MMP-9. These results support the hypothesis that specific growth factors modulate the invasive potential of trophoblasts, and therefore may play an important role in early placental development. Our findings may contribute to the understanding of the pathophysiology of diseases associated with shallow placentation, such as pre-eclampsia.

A study of human leukocyte antigen G expression in hydatidiform moles.

OBJECTIVE: Human leukocyte antigen G (HLA-G) is a nonclassic major histocompatibility gene normally expressed only in extravillous trophoblasts throughout pregnancy. It may be responsible in part for the successful evasion of the hemiallogenic trophoblasts from maternal immune surveillance. We investigated whether HLA-G is expressed in molar pregnancies. STUDY DESIGN: We examined 5 complete hydatidiform mole specimens and 5 partial hydatidiform mole specimens to determine whether HLA-G is expressed by immunohistochemistry and by RNA in situ hybridization analysis. RESULTS: We found that both the protein and RNA of HLA-G is expressed in complete and partial hydatidiform moles. CONCLUSION: HLA-G RNA and protein are expressed in molar pregnancies. HLA-G expression is independent of embryonic development and may therefore be an integral part of placental development. Furthermore, expression of HLA-G in the complete hydatidiform mole, a naturally occurring androgenote, confirms expression of the paternal allele of HLA-G. Imprinting of HLA-G is therefore unlikely to play a role in protecting fetal trophoblasts from maternal immune rejection.

HLA-G expression in extravillous trophoblasts is an intrinsic property of cell differentiation: a lesson learned from ectopic pregnancies.

Human leukocyte antigen (HLA)-G is a major histocompatibility gene expressed almost exclusively in extravillous trophoblasts at the fetal-maternal interface. HLA-G may play a role in protecting the fetus from attack by the maternal natural killer cells. The extravillous trophoblasts invade the decidua and maternal spiral arteries. The factors which regulate the cell-specific expression of HLA-G are unknown. In this study we asked if HLA-G is expressed in extravillous trophoblasts that develop outside of their normal cellular environment, as in the case of ectopic pregnancies. Since all ectopic pregnancies implant in the absence of underlying decidua we also used a placenta accreta as an experimental control. We found that HLA-G mRNA and protein were expressed in the extravillous trophoblasts in the 13 ectopic specimens studied. In a case of placenta accreta (which develops without decidua basalis and is therefore adherent to the underlying myometrium), HLA-G mRNA and protein were also expressed. These results suggest that HLA-G expression is induced in a cell autonomous manner rather than determined by appropriate environmental cues.

Tie-2 and angiopoietin-2 expression at the fetal-maternal interface: a receptor ligand model for vascular remodelling.

The blood vessels at the fetal-maternal interface widen dramatically during pregnancy in order to increase blood flow to nourish the developing fetus. This vessel remodelling destroys normal vessel integrity and encompasses the dissolution of vessel muscle and elastic tissue. It also includes the displacement of endothelial cells by fetal trophoblasts that invade the maternal arteries of the uterus. Interaction between the endothelial cell receptor, Tie-2, and its recently discovered antagonist ligand, angiopoietin-2 (Ang-2), has been implicated in the loosening of vessel structure. Using Northern blot hybridization and RNA in-situ hybridization analysis the expression pattern of Tie-2, and Ang-2 in the placenta throughout pregnancy, was investigated. We found Ang-2 expressed in the syncytiotrophoblast during the first trimester. In addition to the expected expression of the Tie-2 receptor in both fetal and maternal endothelial cells, we observed Tie-2 expression in endovascular invasive trophoblasts. These cells of epithelial origin invade the uterine spiral arteries and acquire endothelial cell properties. The temporal- and lineage-specific pattern of expression of Tie-2 and Ang-2 suggests that this receptor-ligand pair functions during the critical phase of development of the fetal vasculature and reworking of the maternal vessels during normal placentation.

Lack of human leukocyte antigen-G expression in extravillous trophoblasts is associated with pre-eclampsia.

Pre-eclampsia, a common complication of first pregnancies, is thought to result from a poorly perfused placenta and may reflect an abnormal maternal immune reaction to the hemiallogenic fetus. Human leukocyte antigen (HLA)-G, a major histocompatibility tissue-specific antigen expressed in extravillous trophoblast cells (fetal-derived), may protect trophoblasts from maternal-fetal immune intolerance and allow these cells to invade the uterus. Through RNA in-situ hybridization analysis, we studied the expression pattern of HLA-G in normal placentae and placentae from pregnancies complicated by severe pre-eclampsia. In normal placenta we found HLA-G expression in the anchoring extravillous trophoblasts with an increasing gradient of expression in the more invasive cells. However, in nine out of 10 pre-eclamptic placentae HLA-G expression was absent or reduced. We conclude that HLA-G is normally expressed in invasive trophoblasts and HLA-G expression is defective in most pre-eclamptic placentae. We propose that trophoblasts lacking HLA-G are vulnerable to attack by the maternal immune system. These defective trophoblasts will be unable to invade the maternal spiral arteries effectively, thereby developing vessels which cannot adequately nourish the developing placenta. This poorly perfused placenta may initiate the systemic cascade of events associated with pre-eclampsia.

Tamoxifen exerts oestrogen-agonistic effects on proliferation and plasminogen activation, but not on gelatinase activity, glycogen metabolism and p53 protein expression, in cultures of oestrogen-responsive human endometrial adenocarcinoma cells.

To elucidate potential mechanisms involved in the increased incidence of endometrial carcinomas in tamoxifen-treated patients, we examined the in-vitro effects of tamoxifen on endometrial cancer cells. The effects of tamoxifen, alone and in combination with oestradiol, on cell proliferation, plasminogen activator (PA) activity, glycogen synthase and phosphorylase activities, p53 protein concentration, and collagenase expression were assessed in two human adenocarcinoma cell lines. These lines were the oestrogen receptor-positive (Ishikawa) cells, representing a well-differentiated endometrial adenocarcinoma, and oestrogen receptor-negative (HEC-1A) cells, derived from a poorly differentiated endometrial adenocarcinoma. Tamoxifen or oestradiol alone and their combination significantly enhanced cellular proliferation of Ishikawa but not of HEC-1A cells. Both lines produced appreciable PA activity, most of which was of the urokinase type. Tamoxifen and oestradiol stimulated this activity in Ishikawa cells but not in HEC-1A cells. The effect of oestradiol was dose-dependent in a linear fashion, while tamoxifen produced a stimulation peaking at 10(-8) M and declining at higher concentrations. Tamoxifen in combination with oestradiol exhibited a synergistic effect on proliferation and on PA activity. The response of PA extended beyond the increase in proliferation, leading to higher specific activity of PA in the tamoxifen-treated cultures. In Ishikawa cells, oestradiol also increased glycogen synthase and glycogen phosphorylase activities, while tamoxifen markedly suppressed these enzymes. Oestradiol, tamoxifen, and their combination had no apparent effect on the expression of protein p53 in Ishikawa cells, or on gelatinase activity in either Ishikawa or HEC-1A cells. The present findings imply that tamoxifen produces oestrogen-agonistic effects on cell proliferation and PA activity, and oestrogen antagonistic effects on glycogen synthase and glycogen phosphorylase activities, but fails to regulate p53 and gelatinase expression. The tamoxifen-responsive systems were only observed in oestrogen-responsive adenocarcinoma cells. Thus, only certain potential oncogenic effects of tamoxifen can be simulated in vitro, and when present, these effects are enhanced in the presence of oestradiol.

Kv3.3b: a novel Shaw type potassium channel expressed in terminally differentiated cerebellar Purkinje cells and deep cerebellar nuclei.

A two-step hybridization/subtraction procedure was employed to isolate markers for the later stages of Purkinje cell differentiation. From this screen, a novel Shaw potassium channel cDNA (Kv3.3b) was identified that is developmentally regulated. Expression of this channel is highly enriched in the brain, particularly in the cerebellum, where its expression is confined to Purkinje cells and deep cerebellar nuclei. Sequence analysis revealed that it is an alternatively spliced form of the mouse Kv3.3 gene, and that the previously reported Kv3.3 mRNA (Ghanshani et al., 1992) is not expressed in cerebellum. Expression of the Kv3.3b mRNA begins in cerebellar Purkinje cells between postnatal day 8 (P8) and P10 and continues through adulthood, coinciding with elaboration of the mature Purkinje cell dendritic arbor. The timing of expression of Kv3.3b mRNA is maintained in mixed, dissociated primary cerebellar cell culture. These results suggest that the Kv3.3b K+ channel function is restricted to terminally differentiated Purkinje cells, and that analysis of the mechanisms governing its expression in vivo and in vitro can reveal molecular mechanisms governing Purkinje cell differentiation.