Soluble syndecan-1 and glycosaminoglycans in preeclamptic and normotensive pregnancies

Extracellular matrix components in preeclampsia

Preeclampsia (PE) is a gestational complication affecting 5% to 10% of all pregnancies. PE is characterized by hypertension and endothelial dysfunction, whose etiology involves, among other factors, alterations in the extracellular matrix (ECM) that can compromise vascular remodeling and trophoblast invasion, ie, processes essential for placental development. Endothelial dysfunction is caused by release of antiangiogenic factors, mainly a soluble fms-like tyrosine kinase-1 (sFlt-1), which antagonizes two endothelial angiogenic factors, the vascular endothelial growth factor (VEGF) and placental growth factor (PLGF). This angiogenic imbalance contributes to clinical symptoms including hypertension and multisystem dysfunction. This review aims to summarize recent advances in understanding PE, particularly with altered ECM components such as heparan sulfate proteoglycans, the glycosidase heparanase, fibronectin, collagen XVIII (endostatin), and metalloproteases. This comprehensive narrative review was conducted on PubMed from 1994 to 2024, focusing on articles on the pathophysiology of PE, particularly endothelial dysfunction caused by ECM modifications. The data shows a reduced expression of matrix metalloproteinases, increased collagen fragment XVIII, and significant changes in fibronectin associated with PE. Furthermore, endothelial dysfunction was associated with increased degradation of heparan sulfate chains from proteoglycans and increased sFlt-1. Understanding these ECM modifications is crucial for developing potential new therapeutic interventions that improve maternal and fetal outcome in PE.

Maldistribution of fluid in preeclampsia: a secondary kinetic analysis

BACKGROUND

Hypovolemia and peripheral edema are frequent components of preeclampsia. The level of the dysregulation of the body fluid distribution is unclear, which complicates the choice of infusion fluid during surgery. The present fluid kinetic study challenges whether the maldistribution of fluid is due to increased capillary leakage or to poor return of already distributed fluid, which occurs via lymphatic pathways.

METHODS

Ringeŕs solution was infused in 10 awake non-pregnant women, eight healthy pregnant women, and in eight women with mild-to-moderately severe preeclampsia. Distribution and redistribution of the infused fluid was calculated with mixed models kinetics based on the excreted urine volumes and 675 measurements of hemodilution. Differences in fluid kinetics between the three groups were studied with covariance analysis.

RESULTS

The return flow of fluid volume to the plasma after distribution (rate parameter k21) was almost zero in women with preeclampsia, while the rate was normal in the other two groups (P< 0.001). By contrast, the capillary leakage rate of fluid in response to the infusion (k12) was normal. The urinary excretion (k10) was moderately accelerated.

CONCLUSION

Decreased flow of extravascular fluid to the plasma was the key disturbance in women with preeclampsia. Such decreased flow alone promotes hypovolemia, peripheral edema, and hypoalbuminemia, and may be explained by inhibition of lymphatic pumping and/or a decreased interstitial hydrostatic pressure due to the presence of vasoactive and inflammatory signal molecules. The moderately accelerated urine flow may be due to "pressure diuresis" in response to hypertension.

Characterization of Vascular Patterns Associated with Endothelial Glycocalyx Damage in Early- and Late-Onset Preeclampsia

This paper provides an assessment of molecular and functional changes in blood vessels, and a description of vascular patterns during preeclampsia (PE). Patients with normal pregnancy, and pregnancy complicated by PE at earlier (20-34 weeks) and later terms (≥34 weeks) underwent a 24 h monitoring of blood pressure, central hemodynamics, arterial stiffness, and myocardial function. The blood levels of the structural components of endothelial glycocalyx (eGC): syndecan-1 (SDC 1), heparan sulfate proteoglycan 2 (HSPG2), and hyaluronic acid (HA) were determined. In early-onset PE, the vascular pattern comprised changes in all structural components of eGCs, including transmembrane proteoglycans levels, and severe disorders of central hemodynamics, arterial stiffness, and myocardial changes, probably leading to more severe course of PE and the formation of morphological grounds for cardiovascular disorders. The vascular pattern in late-onset PE, including changes in HA levels, central hemodynamics, and myocardial function, may be a signal of potential cardiovascular disorder. PE may change adaptive hemodynamic responses to a pathological reaction affecting both arterial elasticity and the left ventricular myocardium, with its subsequent hypertrophy and decompensation, leading to a delayed development of cardiovascular disorders after PE. Further clinical studies of these indicators will possibly identify predictors of PE and long-term consequences of the disease.

Circulating concentrations of glycocalyx degradation products in preeclampsia

Background and Objectives: Preeclampsia is a multisystem disorder that affects maternal endothelium. The glycocalyx lines and protects the endothelial surface. In severe systemic diseases, like sepsis, it is shed and glycocalyx degradation products can be detected in increased concentrations in plasma. The aim of this study was to compare circulating concentrations of glycocalyx degradation products in degrees of preeclampsia severity.

Study design: In this observational study, we included women from the South African PROVE biobank. Women were divided into normotensive controls, women with preeclampsia without end-organ complications, women with a single end-organ complication and women with multiple end-organ complications. Plasma samples taken at inclusion after diagnosis (preeclampsia cases) or at admission for delivery (normotensive controls) were analyzed with ELISA for syndecan-1, hyaluronic acid and thrombomodulin and compared between groups.

Results: Women with preeclampsia (n = 47) had increased plasma concentrations of hyaluronic acid (100.3 ng/ml IQR 54.2–204 vs. 27.0 ng/ml IQR (13.5–66.6), p < 0,001) and thrombomodulin (4.22 ng/ml IQR 3.55–5.17 vs. 3.49 ng/ml IQR 3.01–3.68, p = 0.007) but not syndecan-1 compared with normotensive women (n = 10). There were no differences in plasma concentration in any of these biomarkers in women with preeclampsia with no end-organ complications (n = 10) compared with women with preeclampsia and one end-organ complication (n = 24). Women with preeclampsia with two or more end-organ complications (n = 13) had increased plasma concentrations of thrombomodulin (5.46 ng/ml, IQR 4.85–7.83 vs. 4.66 ng/ml, IQR 3.45–4.88, p = 0.042) compared with women with preeclampsia and no end-organ complications.

Conclusion: Thrombomodulin was associated with disease severity and may be valuable for risk-stratifying women with preeclampsia.

How trophoblasts fuse: an in-depth look into placental syncytiotrophoblast formation

In humans, cell fusion is restricted to only a few cell types under normal conditions. In the placenta, cell fusion is a critical process for generating syncytiotrophoblast: the giant multinucleated trophoblast lineage containing billions of nuclei within an interconnected cytoplasm that forms the primary interface separating maternal blood from fetal tissue. The unique morphology of syncytiotrophoblast ensures that nutrients and gases can be efficiently transferred between maternal and fetal tissue while simultaneously restricting entry of potentially damaging substances and maternal immune cells through intercellular junctions. To maintain integrity of the syncytiotrophoblast layer, underlying cytotrophoblast progenitor cells terminate their capability for self-renewal, upregulate expression of genes needed for differentiation, and then fuse into the overlying syncytium. These processes are disrupted in a variety of obstetric complications, underscoring the importance of proper syncytiotrophoblast formation for pregnancy health. Herein, an overview of key mechanisms underlying human trophoblast fusion and syncytiotrophoblast development is discussed.

Transmission electron microscopy demonstration of reduced endothelial glycocalyx in severe preeclampsia

INTRODUCTION

Endothelial glycocalyx is a carbohydrate-rich layer lining the luminal side of blood vessels. Its damage was demonstrated in different groups of critically ill patients. Indirect evidence showed that endothelial glycocalyx degradation might be an important factor in pathophysiology of preeclampsia. The aim of our study was to demonstrate endothelial glycocalyx by transmission electron microscopy and to compare its amount in the omentum vessels of pregnant patients with severe preeclampsia and two control groups.

METHODS

Patients with severe preeclampsia who had a cesarean section were included in the study. Controls were healthy pregnant people at term with an elective cesarean section and non-pregnant patients of reproductive age who underwent laparoscopy for benign conditions. We performed omentum biopsies in all three groups. Samples were prepared for transmission electron microscopy using perfusion with ruthenium red. We measured the amount of endothelial glycocalyx attached to apical plasma membrane of endothelial cells as the area of glycocalyx observed with transmission electron microscope.

RESULTS

In the analysis we included nine patients from each group and demonstrated statistically significant difference in the amount of endothelial glycocalyx among the three groups (p = 0.018). Glycocalyx was significantly reduced in severe preeclampsia (median 1.90 μm², interquartile range 0.80-4.1 μm²) compared to non-pregnant controls (median 14.34 μm², interquartile range 3.80-73.32 μm²⁾; p = 0.021. A trend towards reduced glycocalyx amount in preeclampsia vs. pregnant controls and pregnant controls vs. non-pregnant controls was observed but without statistical significance.

DISCUSSION

Compared to non-pregnant controls the endothelial glycocalyx was significantly reduced in pregnant patients with severe preeclampsia.

A Systematic Review of Maternal Serum Syndecan-1 and Preeclampsia

Exploration of novel biomarkers has been gaining popularity in preeclampsia, which is currently being diagnosed based on clinical criteria alone. Soluble syndecan-1, released from one of the proteoglycans associated with the syncytiotrophoblastic layer of the placenta, is affected in patients with abnormal placentation. This article is the first systematic literature review that evaluates the relationship between the antepartum serum levels of the syndecan-1 and preeclampsia. Eight studies were selected after screening and quality appraisal, and data were analyzed. The serum concentration of syndecan-1 was found to correlate positively with the gestational age in all pregnancies and negatively with the systolic blood pressure in patients with preeclampsia. Extremely low levels of soluble syndecan-1 may be helpful as a predictor for the development of preeclampsia during gestation.

Proteoglycans: Systems-Level Insight into Their Expression in Healthy and Diseased Placentas

Proteoglycan macromolecules play key roles in several physiological processes (e.g., adhesion, proliferation, migration, invasion, angiogenesis, and apoptosis), all of which are important for placentation and healthy pregnancy. However, their precise roles in human reproduction have not been clarified. To fill this gap, herein, we provide an overview of the proteoglycans' expression and role in the placenta, in trophoblast development, and in pregnancy complications (pre-eclampsia, fetal growth restriction), highlighting one of the most important members of this family, syndecan-1 (SDC1). Microarray data analysis showed that of 34 placentally expressed proteoglycans, SDC1 production is markedly the highest in the placenta and that SDC1 is the most upregulated gene during trophoblast differentiation into the syncytiotrophoblast. Furthermore, placental transcriptomic data identified dysregulated proteoglycan genes in pre-eclampsia and in fetal growth restriction, including SDC1, which is supported by the lower concentration of syndecan-1 in maternal blood in these syndromes. Overall, our clinical and in vitro studies, data analyses, and literature search pointed out that proteoglycans, as important components of the placenta, may regulate various stages of placental development and participate in the maintenance of a healthy pregnancy. Moreover, syndecan-1 may serve as a useful marker of syncytialization and a prognostic marker of adverse pregnancy outcomes. Further studies are warranted to explore the role of proteoglycans in healthy and complicated pregnancies, which may help in diagnostic or therapeutic developments.

Prothrombotic state associated with preeclampsia

PURPOSE OF REVIEW

Preeclampsia is a common complication of pregnancy and contributes significantly to maternal and fetal morbidity and mortality. A protective hypercoagulable state is often developed during late pregnancy and can evolve into a prothrombotic state in patients with preeclampsia. The underlying mechanism of this prothrombotic transition remains poorly understood. We discuss recent progress in understanding the pathophysiology of preeclampsia and associated prothrombotic state.

RECENT FINDINGS

The hypercoagulable state developed during pregnancy is initiated by placental factors and progresses into the prothrombotic state in preeclampsia when the placenta is subjected ischemic and oxidative injuries. The cause of the preeclampsia-induced prothrombotic state is multifactorial, involving not only placental factors but also maternal conditions, which include genetic predisposition, preexisting medical conditions, and conditions acquired during pregnancy. Endotheliopathy is the primary pathology of preeclampsia and contributes to the prothrombotic state by inducing the dysregulation of coagulation, platelets, and adhesive ligands.

SUMMARY

Patients with preeclampsia often develop a severe prothrombotic state that predisposes them to life-threatening thrombosis and thromboembolism during and after pregnancy. Early recognition and treatment of this prothrombotic state can improve maternal and infant outcomes of preeclampsia patients.