Cooperation over conflict at the maternal-fetal interface

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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.

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.

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.