Longitudinal analysis of maternal serum Follistatin concentration in normal pregnancy and preeclampsia

Multi-omics analysis of placental metabolomics and transcriptomics datasets reveals comprehensive insights into the pathophysiology of preeclampsia

Preeclampsia, a life-threatening pregnancy complication, remains a major global health concern. Understanding the complex molecular mechanisms underlying this disorder is crucial for improving both diagnostics and therapeutic strategies. In this study, a multi-omics approach based on NMR metabolomics and RNA-seq transcriptomics analyses was conducted to analyze placental tissue samples obtained from patients with preeclampsia and healthy controls. Metabolomics data analysis results indicated alterations in several metabolite levels including lactate, myo-inositol, glutamate, glutamine, valine, leucine, isoleucine, creatinine, alanine, taurine, choline, phosphocholine, glycerophosphocholine, ethanolamine, and dihydroxyacetone. These alterations cause significant disruptions in the Krebs cycle, energy, lipid, and amino acid metabolisms. Concurrently, transcriptomics data analysis identified 10 upregulated and 37 downregulated genes (|log2FC= > 1 and padj < 0.05) in preeclampsia patients. Identified genes were linked to critical roles such as vasoconstriction, angiogenesis, inflammation, hormonal balance, oxidative stress, and collagen integrity. Multi-omics data analysis revealed the association of certain metabolites with several other genes. A gene interaction network formed by these genes resulted in a lower protein-protein interaction enrichment value (p-value < 1e-16) compared to the network formed with the differentially expressed genes (p-value = 0.0183) which suggests the importance of considering multiple omics levels for a comprehensive understanding of the disease.

Low follistatin level is a causal risk factor for spontaneous abortion: a two-sample mendelian randomization study

Background

Recurrent pregnancy loss is a distressing event during pregnancy, and understanding its causal factors is crucial. Follistatin, a glycoprotein involved in folliculogenesis and embryogenesis, has been implicated as a potential contributor to the risk of spontaneous abortion. However, establishing a causal relationship requires rigorous investigation using robust methods.

Methods

In this study, we utilized mendelian randomization (MR), a powerful genetic epidemiological approach, to examine the causal relationship between follistatin levels and spontaneous abortion. We obtained instrumental variables strongly associated with follistatin levels from large-scale genome-wide association from the IEU database. The inverse variance weighting (IVW) method was taken as gold standard. We also performed sensitivity test to evaluate the robustness of our result.

Results

MR analysis revealed a significant causal relationship between low follistatin levels and spontaneous abortion (p = 0.03). Sensitivity analyses, including pleiotropy test, heterogeneity test, and leave-one-out analysis, all supported the robustness of our findings.

Conclusion

Our study provides compelling evidence supporting the causal relationship between low follistatin levels and increased risk of spontaneous abortion. These findings underscore the importance of follistatin in the etiology of spontaneous abortion and suggest potential preventive interventions. Modulating follistatin levels or relevant pathways could hold promise for reducing the incidence of spontaneous abortion and improving reproductive outcomes. The utilization of MRs strengthens the validity of our results by mitigating confounding and reverse causality biases. Further research is needed to elucidate the underlying molecular mechanisms and explore therapeutic strategies targeting follistatin levels.

Maternal Serum Activin A, Inhibin A and Follistatin-Related Proteins across Preeclampsia: Insights into Their Role in Pathogenesis and Prediction

BACKGROUND

Within the endocrine-paracrine signalling network at the maternal-foetal interface, the activin-inhibin-follistatin system modulates extravillous trophoblast invasion, suggesting a potential role in preeclampsia pathogenesis. This study aimed to compile the evidence published in the last decade regarding the variation in maternal serum activins, inhibin- and follistatin-related proteins in preeclamptic pregnancies compared to healthy pregnancies, and to discuss their role in predicting and understanding the pathophysiology of preeclampsia.

MATERIAL AND METHODS

A scoping review was conducted in MEDLINE, EMBASE and LILACS databases to identify studies published within the last ten years (2012-2022).

RESULTS

Thirty studies were included. None of the studies addressed maternal serum changes of isoforms different from activin A, inhibin A, follistatin, and follistatin-like 3. Sixteen studies evaluated the potential of these isoforms in predicting preeclampsia through the area under the curve from a receiver operating characteristic curve.

CONCLUSIONS

In preeclampsia, inhibin A is upregulated in all trimesters, whereas activin A increases exclusively in the late second and third trimesters. Serum follistatin levels are reduced in women with preeclampsia during the late second and third trimesters. However, changes in follistatin-like 3 remain inconclusive. Inhibin A and activin A can potentially serve as biomarkers of early-onset preeclampsia based on the outcomes of the receiver operating characteristic curve analysis. Further investigations are encouraged to explore the feasibility of quantifying maternal serum levels of activin A and inhibin A as a clinical tool in early preeclampsia prediction.

Follistatin Is a Novel Chemoattractant for Migration and Invasion of Placental Trophoblasts of Mice

Follistatin (FST) as a gonadal protein is central to the establishment and maintenance of pregnancy. Trophoblasts' migration and invasion into the endometrium are critical events in placental development. This study aimed to elucidate the role of FST in the migration and invasion of placental trophoblasts of mice. We found that FST increased the vitality and proliferation of primary cultured trophoblasts of embryonic day 8.5 (E8.5) mice and promoted wound healing of trophoblasts. Moreover, FST significantly induced migration of trophoblasts in a microfluidic device and increased the number of invasive trophoblasts by Matrigel-coated transwell invasion assay. Being treated with FST, the adhesion of trophoblasts was inhibited, but intracellular calcium flux of trophoblasts was increased. Western blotting results showed that FST had no significant effects on the level of p-Smad3 or the ratio of p-Smad3/Smad3 in trophoblasts. Interestingly, FST elevated the level of p-JNK; the ratio of p-JNK/JNK; and expression of migration-related proteins N-cadherin, vimentin, ezrin and MMP2 in trophoblasts. Additionally, the migration of trophoblasts and expression of N-cadherin, vimentin, and MMP2 in trophoblasts induced by FST were attenuated by JNK inhibitor AS601245. These findings suggest that the elevated FST in pregnancy may act as a chemokine to induce trophoblast migration and invasion through the enhanced JNK signaling to maintain trophoblast function and promote placental development.

Follistatin dysregulation impaired trophoblast biological functions by GDF11-Smad2/3 axis in preeclampsia placentas

INTRODUCTION

Preeclampsia (PE) is one of the main causes of maternal, fetal, and neonatal mortality. So far, the underlying mechanism of this pregnancy-specific syndrome remains unelucidated. The expression of Follistatin (FST) decreased in maternal serum (especially early onset severe PE) and placental trophoblasts of PE patients. However, whether FST-deficiency in preeclamptic placentas alters trophoblast function remains to be determined.

METHODS

Trophoblast cell lines were cultured in vitro and LV3 short hairpin RNA (shRNA) was used to silence FST. Growth and differentiation factor 11 (GDF11) expression level in placentas and serum were detected by immunohistochemistry and enzyme-linked immune-sorbent assay, respectively. To verify the effect of reduced FST expression on trophoblasts, microRNA-24-3p, which was predicted to target the 3'-untranslated region (3'-UTR) of FST, was screened out, and miR-24-3p mimic, inhibitor was used to regulate FST expression in trophoblasts.

RESULTS

Downregulation of FST significantly enhanced the apoptosis and impaired migration and invasion of trophoblast. Reduced FST caused the upregulation of GDF11 in trophoblasts. Interestingly, GDF11 reduced in preeclamptic placental microvascular endothelial cells. Dysregulation of FST-GDF11-Smad2/3 signaling pathway, leading to increased apoptosis of trophoblast. Expression levels of miR-24-3p, was significantly elevated in preeclamptic placentas. Trophoblast cells transfected with miR-24-3p mimics displayed impaired migration and invasion and increased apoptosis. Treated by miR-24-3p inhibitor, trophoblast cells exhibited rescued function.

DISCUSSION

FST-deficiency impaired trophoblast function by upregulating GDF11 levels in trophoblasts. The regulation of FST-GDF11-Smad2/3 axis by microRNAs mimic or inhibitor may be critical to trophoblast function regulation and helps to deepen our understanding of the molecular mechanism of PE.

Serum and urine profiles of TGF-β superfamily members in reproductive aged women

BACKGROUND

TGF-β superfamily members are important biomarkers of reproductive health in women desiring fertility and during pregnancy. TGF-β proteins derived from the ovary and/or placenta have been detected in serum in women, but there have been very few attempts to measure them non-invasively, such as in urinary samples, and to compare them to serum concentrations.

METHODS

We measured inhibin A, inhibin B, total inhibin, AMH, activin A, activin B, activin AB, follistatin, the GDF-9/BMP-15 complex, and GDF-15 in paired serum and urine samples from healthy reproductive aged women and in pregnant (second trimester) women.

RESULTS

We detected all hormones in serum in both pregnant and non-pregnant women. Inhibin A, total inhibin, activin A, activin AB, follistatin, and GDF-15 were significantly higher in pregnant than in non-pregnant women. GDF-15 was the only hormone consistently detected in urine. We also measured, for the first time, the GDF-9/BMP-15 functional heterodimer and the GDF-15 protein harboring the H202D polymorphism.

CONCLUSIONS

We report the successful measurement of the GDF-9/BMP-15 heterodimer (its native form) in serum and the ability to measure GDF-15 non-invasively, in urinary samples. This novel GDF-15 assay also captures the antigen in the presence of a common genetic variant.

Multiplex Analysis of Circulating Maternal Cardiovascular Biomarkers Comparing Preeclampsia Subtypes

Preeclampsia, a hypertensive pregnancy disorder, links to increased long-term maternal cardiovascular disease (CVD). The risk is further increased with early-onset preeclampsia (EPE) and delivery of a growth-restricted child. We hypothesized that circulating biomarkers associated with CVD risk differed between preeclampsia subtypes and controls. We compared EPE; n=37, delivery <week 34, late-onset preeclampsia (LPE); n=29, delivery ≥week 34, and normotensive controls (n=49) using Olink Proseek multiplex CVD I assay (targeting 92 biomarkers). We stratified analysis to uteroplacental spiral artery acute atherosis presence in preeclampsia patients, sharing morphological similarities with atherosclerosis. We found 47 CVD-related biomarkers differing between the groups, 42 markers between normotensive controls and EPE, 28 markers between normotensive controls and LPE, and 9 markers between EPE and LPE. Among these 9 markers, ST2 (ST2 protein), MMP (matrix metalloproteinase) 1, MMP3, and fractalkine (CX3CL1) were uniquely dysregulated in EPE. Principal component (PC) analysis of the differing markers identified 4 clusters (named PC1-PC4) that largely separated the preeclampsia and control groups as well as pregnancies with low and high circulating PlGF (placental growth factor). The combination of the single markers PlGF, ST2, MMP1, MMP3, and CX3CL1 had a high discriminatory property to differentiate between EPE and LPE. Preeclampsia with acute atherosis or with fetal growth restriction could be differentiated by Olink biomarkers as compared with preeclampsia without these features. We identified specific CVD-related biomarkers in pregnancy depending on preeclampsia subtypes and uteroplacental acute atherosis. Assessment of these pregnancy measured biomarkers' relation to long-term cardiovascular dysfunction and hard end points is warranted.

The role of follistatin and granulocyte-colony stimulating factor in HIV-associated pre-eclampsia

KwaZulu-Natal has a high burden of HIV infection and high blood pressure, specifically pre-eclampsia (PE) in pregnancy. Follistatin (FS) and granulocyte-colony stimulating factor (G-CSF) are two glycoproteins involved in PE pathogenesis. In light of the high maternal mortality and morbidity in South Africa (SA), we investigated the expression of FS and G-CSF in the duality of HIV-associated PE. Serum samples of normotensive and pre-eclamptic women were analysed using the Bio-Plex Multiplex Immunoassay. FS expression was significantly reduced in pre-eclamptic (median = 372.0, IQR = 719.2) compared to normotensive (median = 1569.0, IQR = 2043.0) (p < 0.0001). Furthermore, we detected significant FS expression across all study groups. There was a significant difference between HIV -ve normotensive (median = 9.0, IQR = 7.0) vs HIV +ve normotensive (median = 12.0, IQR = 5.0) groups. Additionally, G-CSF expression was notably higher in HIV +ve normotensive when compared to all study groups. This study demonstrated a downregulation of FS and G-CSF expression in PE, compared to normotensive pregnancies. This finding may be attributed to oxidative stress and its immunoregulatory role in the hyperinflammatory milieu of PE. HIV status had no effect on both analytes, albeit upregulated due to immune reconstitution emanating from highly active antiretroviral therapy. Our novel findings suggest that FS and G-CSF may have a potential predictor test value in early pregnancy, hence work on this is ongoing.

GLYCOSYLATED FIBRONECTIN AND INHIBIN ARE LOWER AND ANTI-MÜLLERIAN HORMONE IS HIGHER IN UMBILICAL CORD BLOOD WHEN MOTHERS HAVE PREECLAMPSIA

Objective: Preeclampsia is a common disorder of pregnancy, causing significant morbidity and mortality for mothers and infants. Several molecules, including glycosylated fibronectin (GlyFn), the inhibin-related proteins, anti-müllerian hormone (AMH), and the insulin-like growth factor axis, are altered in maternal plasma in the setting of preeclampsia; however, these molecules have not been previously measured in cord blood of infants born to mothers with preeclampsia, which may represent changes in fetal physiology. We evaluated potential biomarkers of preeclampsia in umbilical cord blood to fill the gap in knowledge. Methods: This is a case-control study of 196 neonates born at a tertiary teaching hospital in Boston from 2010-2017. Forty-nine neonates born to mothers with preeclampsia were matched 1:3 by gestational age, sex, and birth weight z-score with 147 controls. Eleven analytes were measured in cord blood by enzyme-linked immunosorbent assay. Binary logistic regression analyses were performed to evaluate associations between preeclampsia and analytes. Results: Mean cord blood levels of GlyFn and total inhibin were significantly lower in neonates born to mothers with preeclampsia compared to controls, and AMH levels were significantly higher in males born to mothers with preeclampsia than male controls. Associations remained significant after controlling for maternal and neonatal characteristics. Conclusion: Cord blood levels of GlyFn and inhibin are decreased and AMH (male) levels are increased in infants of preeclamptic mothers, which is opposite the pattern these biomarkers show in serum of mothers with preeclampsia. These molecules may be important in the pathophysiology and long-term effects of preeclampsia on the developing fetus. Abbreviations: AMH = anti-müllerian hormone; ELISA = enzyme-linked immunosorbent assay; GlyFn = glycosylated fibronectin; IGF = insulin-like growth factor; IGFBP5 = insulin-like growth factor binding protein 5; LOD = limit of detection; PAPP-A = pregnancy-associated plasma protein A; PAPP-A2 = pregnancy-associated plasma protein A2.

The emerging role of follistatin under stresses and its implications in diseases

Follistatin (FST), a single-chain glycosylated protein, is expressed in various tissues. The essential biological function of FST is binding and neutralizing transforming growth factor β (TGF-β) superfamily, including activin, myostatin, and bone morphogenetic protein (BMP). Emerging evidence indicates that FST also serves as a stress responsive protein, which plays a protective role under a variety of stresses. In most cases, FST performs the protective function through its neutralization of TGF-β superfamily. However, under certain circumstances, FST translocates into the nucleus to maintain cellular homeostasis independent of its extracellular antagonism activity. This review provides integrated insight into the most recent advances in understanding the role of FST under various stresses, and the clinical implications corresponding to these findings and discusses the mechanisms to be further studied.

Circulating follistatin in relation to energy metabolism

Recently, substantial evidence has emerged that the liver contributes significantly to the circulating levels of follistatin and that circulating follistatin is tightly regulated by the glucagon-to-insulin ratio. Both observations are based on investigations of healthy subjects. These novel findings challenge the present view of circulating follistatin in human physiology, being that circulating follistatin is a result of spill-over from para/autocrine actions in various tissues and cells. Follistatin as a liver-derived protein under the regulation of glucagon-to-insulin ratio suggests a relation to energy metabolism. In this narrative review, we attempt to reconcile the existing findings on circulating follistatin with the novel concept that circulating follistatin is a liver-derived molecule regulated by the glucagon-to-insulin ratio. The picture emerging is that conditions associated with elevated levels of circulating follistatin have a metabolic denominator with decreased insulin sensitivity and/or hyperglucagoneimia.

Serum Galanin Levels in Young Healthy Lean and Obese Non-Diabetic Men during an Oral Glucose Tolerance Test

Galanin (GAL) is a neuropeptide involved in the homeostasis of energy metabolism. The objective of this study was to investigate the serum levels of GAL during an oral glucose tolerance test (OGTT) in lean and obese young men. This cross-sectional study included 30 obese non-diabetic young men (median 22 years; mean BMI 37 kg/m²) and 30 healthy lean men (median 23 years; mean BMI 22 kg/m²). Serum GAL was determined during OGTT. The results of this study include that serum GAL levels showed a reduction during OGTT compared with basal levels in the lean subjects group. Conversely, serum GAL levels increased significantly during OGTT in obese subjects. Serum GAL levels were also higher in obese non-diabetic men compared with lean subjects during fasting and in every period of the OGTT (p < 0.001). Serum GAL levels were positively correlated with BMI, total fat, visceral fat, HOMA–IR, total cholesterol, triglycerides and Leptin. A multiple regression analysis revealed that serum insulin levels at 30, 60 and 120 minutes during the OGTT is the most predictive variable for serum GAL levels (p < 0.001). In conclusion, serum GAL levels are significantly higher in the obese group compared with lean subjects during an OGTT.

Serum Adipsin Levels throughout Normal Pregnancy and Preeclampsia

Adipsin is a protease produced at high levels by adipose tissue. It is involved in complement activation and metabolic control. The objective of this study was to determine the changes in adipsin levels during different stages of normal pregnancy, and its association with obstetric outcomes, such as preeclampsia. This nested case-control study in a longitudinal cohort included normal pregnant (n = 54) and preeclamptic (n = 18) women, both followed throughout pregnancy. Additionally, some of the normal pregnant women were followed up three months postpartum (n = 18). Healthy non-pregnant women were also studied during their menstrual cycle (n = 20). The results of this study show that in healthy non-pregnant women, adipsin levels did not change significantly during the menstrual cycle. In normal pregnant women, adipsin levels were lower (p < 0.01) when compared with non-pregnant healthy women, but these serum levels increased again during postpartum (p < 0.001). Adipsin levels were significantly elevated in preeclamptic women in late pregnancy (P < 0.01). A significant correlation was not found between leptin and adipsin during the three periods of gestation studied in healthy pregnant and preeclamptic women. Our results suggest that adipsin may be involved in pregnancy-associated metabolic changes. Moreover, the increase of adipsin levels towards late gestation in preeclamptic women could be related to the pathophysiology of this disease.