Simcha Yagel

ISUOG Practice Guidelines (updated): sonographic screening examination of the fetal heart

The International Society of Ultrasound in Obstetrics and Gynecology (ISUOG) is a scientific organization that encourages safe clinical practice and high-quality teaching and research related to diagnostic imaging in women’s healthcare. The ISUOG Clinical Standards Committee (CSC) has a remit to develop Practice Guidelines and Consensus Statements that provide healthcare practitioners with a consensus-based approach for diagnostic imaging. They are intended to reflect what is considered by ISUOG to be the best practice at the time at which they are issued. Although ISUOG has made every effort to ensure that Guidelines are accurate when issued, neither the Society nor any of its employees or members accept any liability for the consequences of any inaccurate or misleading data, opinions or statements issued by the CSC. The ISUOG CSC documents are not intended to establish a legal standard of care because interpretation of the evidence that underpins the Guidelines may be influenced by individual circumstances, local protocol and available resources. Approved Guidelines can be distributed freely with the permission of ISUOG (info@isuog.org).

Regulation of trophoblast invasion: from normal implantation to pre-eclampsia

Conversion of the maternal spiral arteries into larger competent vessels is one of the essential steps in the development of the normal placenta. This process is apparently dependent on the invasion by trophoblasts of the sub-endometrial area and the spiral arteries. Preeclampsia is characterized by shallow trophoblast invasion and unconverted narrow spiral arteries. This leads to fetal hypoxia that causes endothelial injury that eventually manifest as maternal hypertension, edema, and proteinuria. The following steps have been shown to be involved in the breakthrough of the trophoblasts from the uterine cavity into the decidua and the spiral arteries: trophoblast targeting, adhesion, and detachment from the extracellular matrix (ECM), invasion of the ECM and maternal vessels by proteolysis. Abnormal expression and activity of these molecules may explain in part some of the molecular mechanisms leading to abnormal placentation and the development of preeclampsia.

Novel APC-like properties of human NK cells directly regulate T cell activation

Initiation of the adaptive immune response is dependent on the priming of naive T cells by APCs. Proteomic analysis of unactivated and activated human NK cell membrane-enriched fractions demonstrated that activated NK cells can efficiently stimulate T cells, since they upregulate MHC class II molecules and multiple ligands for TCR costimulatory molecules. Furthermore, by manipulating antigen administration, we show that NK cells possess multiple independent unique pathways for antigen uptake. These results highlight NK cell-mediated cytotoxicity and specific ligand recognition by cell surface-activating receptors on NK cells as unique mechanisms for antigen capturing and presentation. In addition, we analyzed the T cell-activating potential of human NK cells derived from different clinical conditions, such as inflamed tonsils and noninfected and CMV-infected uterine decidual samples, and from transporter-associated processing antigen 2-deficient patients. This in vivo analysis revealed that proinflammatory, but not immune-suppressive, microenvironmental requirements can selectively dictate upregulation of T cell-activating molecules on NK cells. Taken together, these observations offer new and unexpected insights into the direct interactions between NK and T cells and suggest novel APC-like activating functions for human NK cells.

Developmental regulation of the expression of 72 and 92 kd type IV collagenases in human trophoblasts: A possible mechanism for control of trophoblast invasion

OBJECTIVE During early pregnancy fetal cytotrophoblast cells invade the uterus and penetrate the basement membrane, a property that is characteristic of malignant cells. However, unlike tumor invasion, trophoblast invasion of the uterus is under strict control. This control limits invasion, so that it primarily remains confined to the endometrial aspect of the myometrium and continues only until midgestation. The invasive properties of the trophoblast cells are made possible by the activity of proteolytic enzymes that belong to the metalloproteinases and serine proteinases. Type IV collagenase (metalloproteinase) is considered crucial in the extracellular matrix remodeling that takes place during the invasion process. In this study we set out to characterize the invasive properties of trophoblast cells at different stages of pregnancy. STUDY DESIGN Human trophoblast cells were isolated from first- and third-trimester placentas by trypsin digestion and Percoll fractionation and were then cultured under serum-free conditions. The invasive ability of trophoblast cells was determined by the in vitro invasion assay, in which the ability of cells to penetrate an artificial basement membrane was examined. Metalloproteinase activity was measured by zymography, and the expression of messenger ribonucleic acid transcripts of 72 and 92 kd type IV collagenases was examined by reverse transcriptase polymerase chain reaction. RESULTS First-trimester trophoblasts were 3.5 time more invasive in vitro than were third-trimester trophoblast cells (p < 0.005). Although first-trimester trophoblasts secreted both species of type IV collagenase, 72 and 92 kd, in large amounts, third-trimester cells secreted the 92 kd and only minimal amounts of 72 kd type IV collagenase. Moreover, first-trimester trophoblasts secreted significantly more (p < 0.05) 92 kd type IV collagenase than did third-trimester trophoblast. The messenger ribonucleic acid transcript expression of 72 and 92 kd type IV collagenases correlated with the activity of these enzymes secreted by first- and third-trimester trophoblasts. CONCLUSION The described high in situ invasive capacity of first-trimester trophoblast might be explained by the increased expression and production of 72 kd type IV collagenase and the higher expression of 92 kd type IV collagenase by first-trimester trophoblast cells.

A Novel Human-Specific Soluble Vascular Endothelial Growth Factor Receptor 1: Cell Type-Specific Splicing and Implications to Vascular Endothelial Growth Factor Homeostasis and Preeclampsia

A human-specific splicing variant of vascular endothelial growth factor (VEGF) receptor 1 (Flt1) was discovered, producing a soluble receptor (designated sFlt1-14) that is qualitatively different from the previously described soluble receptor (sFlt1) and functioning as a potent VEGF inhibitor. sFlt1-14 is generated in a cell type-specific fashion, primarily in nonendothelial cells. Notably, in vascular smooth muscle cells, all Flt1 messenger RNA is converted to sFlt1-14, whereas endothelial cells of the same human vessel express sFlt1. sFlt1-14 expression by vascular smooth muscle cells is dynamically regulated as evidenced by its upregulation on coculture with endothelial cells or by direct exposure to VEGF. Increased production of soluble VEGF receptors during pregnancy is entirely attributable to induced expression of placental sFlt1-14 starting by the end of the first trimester. Expression is dramatically elevated in the placenta of women with preeclampsia, specifically induced in abnormal clusters of degenerative syncytiotrophoblasts known as syncytial knots, where it may undergo further messenger RNA editing. sFlt1-14 is the predominant VEGF-inhibiting protein produced by the preeclamptic placenta, accumulates in the circulation, and hence is capable of neutralizing VEGF in distant organs affected in preeclampsia. Together, these findings revealed a new natural VEGF inhibitor that has evolved in humans, possibly to protect nonendothelial cells from adverse VEGF signaling. Furthermore, the study uncovered the identity of a VEGF-blocking protein implicated in preeclampsia.

Endometrial NK Cells Are Special Immature Cells That Await Pregnancy

NK cells populate the human endometrium before pregnancy. Unlike decidual NK cells that populate the decidua during pregnancy, the NK cells present in the human endometrium, before pregnancy, have not been fully characterized. In this study, we provide a detailed analysis of the origin, phenotype, and function of endometrial NK cells (eNK). We show that eNK cells have a unique receptor repertoire. In particular, they are negative for NKp30 and chemokine receptor expression, which distinguishes them from any other NK subset described so far. We further show that eNK cells lack NK-specific functional phenotype and activity such as cytokine secretion and cytotoxicity, before IL-15 stimulation. Following such stimulation, endometrial NK cells acquire phenotype and function that are similar to those of decidual NK cells. We therefore suggest that eNK cells are inactive cells (before IL-15 activation and in relation to the known NK activity) that are present in the endometrium before conception, waiting for pregnancy.

Fetal head circumference and length of second stage of labor are risk factors for levator ani muscle injury, diagnosed by 3-dimensional transperineal ultrasound in primiparous women.

OBJECTIVE We evaluated rate of levator ani muscle (LAM) avulsion among primiparae using 3-dimensional transperineal ultrasound to identify possible risk factors for such trauma. STUDY DESIGN We conducted a prospective observational study. Three-dimensional transperineal ultrasound was performed on all subjects. Primiparae were evaluated 24-72 hours after vaginal delivery. In all, 32 nulliparous gravidae (35-41 weeks) and 15 elective cesarean delivery primiparae were evaluated as methodological controls. We compared newborn head circumference (HC), birthweight, second stage duration, maternal age, baby sex, episiotomy, and instrumental delivery. RESULTS LAM trauma was observed in 39 of 210 (18.8%) patients and no controls. Odds ratio for LAM trauma when newborn HC >or= 35.5 cm was 3.343 (95% confidence interval, 1.33-8.42); when second stage duration >or= 110 minutes, odds ratio was 2.27 (95% confidence interval, 1.07-4.81). Logistic regression showed that HC >or= 35.5 and second stage duration >or= 110 minutes increased odds of LAM trauma by a factor of 5.32. CONCLUSION Large HC and prolonged second stage duration are risk factors in LAM trauma. Elective cesarean delivery may prevent LAM trauma.

Complexes of HLA-G Protein on the Cell Surface Are Important for Leukocyte Ig-Like Receptor-1 Function

The nonclassical class I MHC molecule HLA-G is selectively expressed on extravillous cytotrophoblast cells at the maternal-fetal interface during pregnancy. HLA-G can inhibit the killing mediated by NK cells via interaction with the inhibitory NK cell receptor, leukocyte Ig-like receptor-1 (LIR-1). Comparison of the sequence of the HLA-G molecule to other class I MHC proteins revealed two unique cysteine residues located in positions 42 and 147. Mutating these cysteine residues resulted in a dramatic decrease in LIR-1 Ig binding. Accordingly, the mutated HLA-G transfectants were less effective in the inhibition of NK killing and RBL/LIR-1 induced serotonin release. Immunoprecipitation experiments demonstrated the involvement of the cysteine residues in the formation of HLA-G protein oligomers on the cell surface. The cysteine residue located at position 42 is shown to be critical for the expression of such complexes. These oligomers, unique among the class I MHC proteins, probably bind to LIR-1 with increased avidity, resulting in an enhanced inhibitory function of LIR-1 and an impaired killing function of NK cells.

3D and 4D ultrasound in fetal cardiac scanning: a new look at the fetal heart

Over the last decade we have been witness to a burgeoning literature on three‐dimensional (3D) and four‐dimensional (4D) ultrasound‐based studies of the fetal cardiovascular system. Recent advances in the technology of 3D/4D ultrasound systems allow almost real‐time 3D/4D fetal heart scans. It appears that 3D/4D ultrasound in fetal echocardiography may make a significant contribution to interdisciplinary management team consultation, health delivery systems, parental counseling, and professional training.

Pivotal role of CEACAM1 protein in the inhibition of activated decidual lymphocyte functions

Lymphocytes in direct contact with embryonic extravillous trophoblasts constitute more than 40% of decidual cells and appear to play major roles in implantation and early gestation. A unique subset of NK cells, making up 70-80% of decidual lymphocytes, express high levels of CD56 but lack CD16. We have recently demonstrated a novel class I MHC-independent inhibitory mechanism of NK cell cytotoxicity that is mediated by CEACAM1 homotypic interactions. This mechanism is used by some melanoma cells to avoid attack, mainly by CD16(-) NK cells. We now demonstrate that CEACAM1 is expressed on primary extravillous trophoblasts and is upregulated on the vast majority of IL-2-activated decidual lymphocytes, including NK, T, and NKT cells. Importantly, we present evidence that CEACAM1 interactions inhibit the lysis, proliferation, and cytokine secretion of activated decidual NK, T, and NKT cells, respectively. In vivo analysis of decidual lymphocytes isolated from cytomegalovirus-infected (CMV-infected) pregnant women revealed a dramatic increase in the expression of CEACAM1. Finally, we suggest that a novel ligand for this adhesion molecule is present on the surface of CMV-infected fibroblasts. These combined results demonstrate a major role for the CEACAM1 protein in controlling local decidual immune responses.