Dysregulation of Oxygen Sensing/Response Pathways in Pregnancies Complicated by Idiopathic Intrauterine Growth Restriction and Early-Onset Preeclampsia

AC092100.1 promotes angiogenesis in pre-eclampsia through YTHDC2/VEGFA signaling

Aberrant long non-coding RNA (lncRNA) expression has been shown to be involved in the pathological process of pre-eclampsia (PE), yet only a small portion of lncRNAs has been characterized concerning the function and molecular mechanisms involved in PE. This study aimed to investigate the regulatory mechanism of the lncRNA AC092100.1 (AC092100.1) in angiogenesis in PE. In our study, bioinformatics analysis was performed to screen for differentially expressed lncRNAs between normal subjects and PE patients. The levels of AC092100.1 in placental tissues of patients with or without PE were validated using qRT-PCR. The effect of AC092100.1 overexpression on the proliferation, migration, and tube formation of human umbilical vein endothelial cells (HUVECs) was investigated. The binding of AC092100.1 and YT521-B homology domain-containing 2 (YTHDC2) was predicted and verified. The effect of AC092100.1/YTHDC2 on the expression of vascular endothelial growth factor-A (VEGFA) in HUVECs was determined. Finally, a PE mice model was conducted. Fetal mouse growth, the abundance of mesenchymal morphology markers, including hypoxia-inducible factor 1-alpha (HIF-1α), soluble fms-like tyrosine kinase-1 (sFlt-1), soluble endoglin (sEng), Slug, and Vimentin, and endothelial markers, including placental growth factor (PLGF), CD31, and vascular endothelial (VE)-cadherin, in placental tissues were assessed. Here, we found that AC092100.1 was abnormally downregulated in placental tissues from PE patients. We established that AC092100.1 overexpression promoted HUVEC proliferation, migration, and tube formation in vitro. Mechanistically, AC092100.1 induced the accumulation of YTHDC2 and VEGFA through binding to YTHDC2 in HUVECs. Inhibition of YTHDC2 or VEGFA reversed AC092100.1-promoted tube formation. AC092100.1 overexpression contributed to alleviating fetal growth disorder, decreased levels of sEng, HIF-1α, sFlt-1, Slug, and Vimentin, and increased levels of VEGFA, PLGF, CD31, and VE-cadherin in PE mice. Our findings provided evidence supporting the role of the AC092100.1/YTHDC2/VEGFA axis in regulating angiogenesis, which demonstrated a therapeutic pathway for PE targeting angiogenesis.

KLF6 negatively regulates HIF-1α in extravillous trophoblasts under hypoxia

INTRODUCTION

HIF-1α, the master regulator of hypoxia cellular response, is stabilized under low oxygen levels and degraded in the presence of oxygen but its transcription, translation, and degradation are tightly regulated by numerous pathways. KLF6 is a transcription factor involved in proliferation, differentiation, and apoptosis in several cell systems. Under hypoxia it is upregulated in a HIF-1α-dependent manner in extravillous trophoblasts. Considering the importance of hypoxia modulation of EVT behavior through HIF1-α we aimed to study whether KLF6 modulates HIF-1α expression in HTR8/SVneo cells.

METHODS

HTR8/SVneo cells were cultured in a 1 % oxygen chamber or in 3D format where a spontaneous oxygen gradient is generated. qRT-PCR and Western blot were performed to analyze mRNA and protein expression, respectively. SiRNA, shRNA, or plasmids were used to down- or up-regulate gene expression. Wound healing assay was performed under hypoxia to evaluate migration. The NFκB pathway was modulated with dominant negative mutants and a chemical inhibitor. Cobalt chloride was used to block HIF-1α degradation.

RESULTS

KLF6 up- and down-regulation in HTR8/SVneo cells exposed to acute hypoxia revealed a negative regulation on HIF-1α. KLF6 silencing led to a partially HIF-1α-dependent increase in MMP9 and VEGF. The NF-κB pathway and HIF-1α degradation were involved in KLF6-dependent HIF-1α regulation. HTR8/SVneo-3D culture showed that KLF6 negatively regulates HIF-1α in a microenvironment with naturally generated hypoxia.

DISCUSSION

Present results reveal that KLF6 contributes to a fine tune modulation of HIF-1α level under hypoxia. Thus, sustaining a HIF-1α homeostatic level, KLF6 might contribute to control EVT adaptation to hypoxia.

Controlling Trophoblast Cell Fusion in the Human Placenta-Transcriptional Regulation of Suppressyn, an Endogenous Inhibitor of Syncytin-1

Cell fusion in the placenta is tightly regulated. Suppressyn is a human placental endogenous retroviral protein that inhibits the profusogenic activities of another well-described endogenous retroviral protein, syncytin-1. In this study, we aimed to elucidate the mechanisms underlying suppressyn's placenta-specific expression. We identified the promoter region and a novel enhancer region for the gene encoding suppressyn, ERVH48-1, and examined their regulation via DNA methylation and their responses to changes in the oxygen concentration. Like other endogenous retroviral genes, the ERVH48-1 promoter sequence is found within a characteristic retroviral 5' LTR sequence. The novel enhancer sequence we describe here is downstream of this LTR sequence (designated EIEs: ERV internal enhancer sequence) and governs placental expression. The placenta-specific expression of ERVH48-1 is tightly controlled by DNA methylation and further regulated by oxygen concentration-dependent, hypoxia-induced transcription factors (HIF1α and HIF2α). Our findings highlight the involvement of (1) tissue specificity through DNA methylation, (2) expression specificity through placenta-specific enhancer regions, and (3) the regulation of suppressyn expression in differing oxygen conditions by HIF1α and HIF2α. We suggest that these regulatory mechanisms are central to normal and abnormal placental development, including the development of disorders of pregnancy involving altered oxygenation, such as preeclampsia, pregnancy-induced hypertension, and fetal growth restriction.

From Molecules to Imaging: Assessment of Placental Hypoxia Biomarkers in Placental Insufficiency Syndromes

Placental hypoxia poses significant risks to both the developing fetus and the mother during pregnancy, underscoring the importance of early detection and monitoring. Effectively identifying placental hypoxia and evaluating the deterioration in placental function requires reliable biomarkers. Molecular biomarkers in placental tissue can only be determined post-delivery and while maternal blood biomarkers can be measured over time, they can merely serve as proxies for placental function. Therefore, there is an increasing demand for non-invasive imaging techniques capable of directly assessing the placental condition over time. Recent advancements in imaging technologies, including photoacoustic and magnetic resonance imaging, offer promising tools for detecting and monitoring placental hypoxia. Integrating molecular and imaging biomarkers may revolutionize the detection and monitoring of placental hypoxia, improving pregnancy outcomes and reducing long-term health complications. This review describes current research on molecular and imaging biomarkers of placental hypoxia both in human and animal studies and aims to explore the benefits of an integrated approach throughout gestation.

Genome-Wide Analysis of Hypoxia-Inducible Factor Binding Reveals Targets Implicated in Impaired Human Placental Syncytiotrophoblast Formation under Low Oxygen

Preeclampsia (PE) is a common and serious complication of pregnancy with no cure except premature delivery. The root cause of PE is improper development of the placenta-the temporary organ supporting fetal growth and development. Continuous formation of the multinucleated syncytiotrophoblast (STB) layer via differentiation and fusion of cytotrophoblasts (CTBs) is vital for healthy placentation and is impaired in preeclamptic pregnancies. In PE, there is reduced/intermittent placental perfusion, likely resulting in a persistently low O2 environment. Low O2 inhibits differentiation and fusion of CTBs into STB and may thus contribute to PE pathogenesis; however, the underlying mechanisms are unknown. Because low O2 activates a transcription factor complex in cells known as the hypoxia-inducible factor (HIF), the objective of this study was to investigate whether HIF signaling inhibits STB formation by regulating genes required for this process. Culture of primary CTBs, the CTB-like cell line BeWo, and human trophoblast stem cells under low O2 reduced cell fusion and differentiation into STB. Knockdown of aryl hydrocarbon receptor nuclear translocator (a key component of the HIF complex) in BeWo cells restored syncytialization and expression of STB-associated genes under different O2 levels. Chromatin immunoprecipitation sequencing facilitated the identification of global aryl hydrocarbon receptor nuclear translocator/HIF binding sites, including several near genes implicated in STB development, such as ERVH48-1 and BHLHE40, providing new insights into mechanisms underlying pregnancy diseases linked to poor placental O2 supply.

Impact of Endogenic and Exogenic Oxidative Stress Triggers on Pregnant Woman, Fetus, and Child

In all living organisms, there is a delicate balance between oxidation caused by reactive species (RS, also called free radicals) and antioxidant defence [...].

Necrotizing Enterocolitis: The Role of Hypoxia, Gut Microbiome, and Microbial Metabolites

Necrotizing enterocolitis (NEC) is a life-threatening disease that predominantly affects very low birth weight preterm infants. Development of NEC in preterm infants is accompanied by high mortality. Surgical treatment of NEC can be complicated by short bowel syndrome, intestinal failure, parenteral nutrition-associated liver disease, and neurodevelopmental delay. Issues surrounding pathogenesis, prevention, and treatment of NEC remain unclear. This review summarizes data on prenatal risk factors for NEC, the role of pre-eclampsia, and intrauterine growth retardation in the pathogenesis of NEC. The role of hypoxia in NEC is discussed. Recent data on the role of the intestinal microbiome in the development of NEC, and features of the metabolome that can serve as potential biomarkers, are presented. The Pseudomonadota phylum is known to be associated with NEC in preterm neonates, and the role of other bacteria and their metabolites in NEC pathogenesis is also discussed. The most promising approaches for preventing and treating NEC are summarized.

Development and evaluation of a nomogram for adverse outcomes of preeclampsia in Chinese pregnant women

Objective

Preeclampsia, the main cause of maternal and perinatal deaths, is associated with several maternal complications and adverse perinatal outcomes. Some prediction models are uesd to evaluate adverse pregnancy outcomes. However, some of the current prediction models are mainly carried out in developed countries, and many problems are still exist. We, thus, developed and validated a nomogram to predict the risk of adverse pregnancy outcomes of preeclampsia in Chinese pregnant women.

Methods

The clinical data of 720 pregnant women with preeclampsia in seven medical institutions in Chongqing from January 1, 2010, to December 31, 2020, were analyzed retrospectively. The patients were divided into two groups: 180 cases (25%) with adverse outcomes and 540 cases (75%) without adverse outcomes. The indicators were identified via univariate analysis. Logistic regression analysis was used to establish the prediction model, which was displayed by a nomogram. The performance of the nomogram was evaluated in terms of the area under the receiver operating characteristic (ROC) curve, calibration, and clinical utility.

Results

Univariate analysis showed that 24 indicators were significantly different (P < 0.05). Logistic regression analysis showed that gestational age, 24 h urine protein qualitative, and TT were significantly different (P < 0.05). The area under the ROC curve was 0.781 (95% CI 0.737–0.825) in training set and 0.777 (95% CI 0.689–0.865) in test set. The calibration curve of the nomogram showed good agreement between prediction and observation. The analysis of the clinical decision curve showed that the nomogram is of practical significance.

Conclusion

Our study identified gestational age, 24 h urine protein qualitative, and TT as risk factors for adverse outcomes of preeclampsia in pregnant women, and constructed a nomogram that can easily predict and evaluate the risk of adverse pregnancy outcomes in women with preeclampsia.