Preeclampsia link to gestational hypoxia

Preeclampsia and STOX1 (storkhead-box protein 1): Molecular evaluation of STOX1 in preeclampsia

Preeclampsia (PE) is clinically defined as a part of pregnancy characterized by hypertension and multiple organ failure. PE is broadly categorized into two types: "placental" and "maternal". Placental PE is associated with fetal growth restriction and adverse maternal and neonatal outcomes. STOX1 (Storkhead box 1), a transcription factor, discovered through a complete transcript analysis of the PE susceptibility locus of 70,000 bp on chromosome 10q22.1. So far, studies investigating the relationship between STOX1 and PE have focused on STOX1 overexpression, STOX1 isoform imbalance, and STOX1 variations that could have clinical consequence. Initially, the Y153H variation of STOX was associated with the placental form of PE. Additionally, studies focusing on the maternal and fetal interface have shown that NODAL and STOX1 variations play a role together in the unsuccessful remodeling of the spiral arteries. Research specifically addressing the overexpression of STOX1 has shown that its disruption of cellular hemoastasis, leading to impaired hypoxia response, disruption of the cellular antioxidant system, and nitroso/redox imbalance. Furthermore, functional studies have been conducted showing that the imbalance between STOX1 isoforms contributes to the pathogenesis of placental PE. Research indicates that STOX1B competes with STOX1A and that the overexpression of STOX1B reverses cellular changes that STOX1A induces to the pathogenesis of PE. In this review, we aimed at elucidating the relationship between STOX1 and PE as well as function of STOX1. In conclusion, based on a comprehensive literature review, numerous studies support the role of STOX1 in the pathogenesis of PE.

Impaired Endothelium-Dependent Vasodilation and Increased Levels of Soluble Fms-like Tyrosine Kinase-1 Induced by Reduced Uterine Perfusion Pressure in Pregnant Rats: Evidence of Protective Effects with Sodium Nitrite Treatment in Preeclampsia

Preeclampsia (PE) is a hypertensive disorder of pregnancy and is associated with increases in soluble fms-like tyrosine kinase-1 (sFlt-1) and reductions in nitric oxide (NO) levels. Placental ischemia and hypoxia are hypothesized as initial pathophysiological events of PE. Nitrite (NO metabolite) may be recycled back to NO in ischemic and hypoxic tissues. Therefore, this study examined the sodium nitrite effects in an experimental model of PE. Pregnant rats received saline (Preg group) or sodium nitrite (Preg + Na-Nitrite group). Pregnant rats submitted to the placental ischemia received saline (RUPP group) or sodium nitrite (RUPP + Na-Nitrite group). Blood pressure, placental and fetal weights, and the number of pups were recorded. Plasma levels of NO metabolites and sFlt-1 were also determined. Vascular and endothelial functions were also measured. Blood pressure, placental and fetal weights, the number of pups, NO metabolites, sFlt-1 levels, vascular contraction, and endothelium-dependent vasodilation in the RUPP + Na-Nitrite rats were brought to levels comparable to those in Preg rats. In conclusion, sodium nitrite may counteract the reductions in NO and increases in sFlt-1 levels induced by the placental ischemia model of PE, thus suggesting that increased blood pressure and vascular and endothelial dysfunctions may be attenuated by sodium nitrite-derived NO.

A Wireless and Wearable Multimodal Sensor to Non-Invasively Monitor Transabdominal Placental Oxygen Saturation and Maternal Physiological Signals

Poor placental development and placental defects can lead to adverse pregnancy outcomes such as pre-eclampsia, fetal growth restriction, and stillbirth. This study introduces two sensors, which use a near-infrared spectroscopy (NIRS) technique to measure placental oxygen saturation transabdominally. The first one, an NIRS sensor, is a wearable device consisting of multiple NIRS channels. The second one, a Multimodal sensor, which is an upgraded version of the NIRS sensor, is a wireless and wearable device, integrating a motion sensor and multiple NIRS channels. A pilot clinical study was conducted to assess the feasibility of the two sensors in measuring transabdominal placental oxygenation in 36 pregnant women (n = 12 for the NIRS sensor and n = 24 for the Multimodal sensor). Among these subjects, 4 participants had an uncomplicated pregnancy, and 32 patients had either maternal pre-existing conditions/complications, neonatal complications, and/or placental pathologic abnormalities. The study results indicate that the patients with maternal complicated conditions (69.5 ± 5.4%), placental pathologic abnormalities (69.4 ± 4.9%), and neonatal complications (68.0 ± 5.1%) had statistically significantly lower transabdominal placental oxygenation levels than those with an uncomplicated pregnancy (76.0 ± 4.4%) (F (3,104) = 6.6, p = 0.0004). Additionally, this study shows the capability of the Multimodal sensor in detecting the maternal heart rate and respiratory rate, fetal movements, and uterine contractions. These findings demonstrate the feasibility of the two sensors in the real-time continuous monitoring of transabdominal placental oxygenation to detect at-risk pregnancies and guide timely clinical interventions, thereby improving pregnancy outcomes.

A Dual-Fluorescence Molecular "Open Bridge" for Evaluating Gestational Hypoxia and Hypertension under the Stress of SARS-Cov-2

Gestational hypertension is a dangerous condition that is sometimes fatal to the mother and her unborn off-spring. The strong connection between hypertension and hypoxia is emphasized by the currently rampaging SARS-Cov-2, which can induce similar conditions, in which hemolysis and the subsequent oxidative damage may release hemoglobin and tissue factor into the serum. To detect these dangerous proteins normally absent from serum, we mimic the molecular pathology of hypoxia, resulting in a synthesizable molecular machine around which a new bioassay can be designed to simultaneously detect the two proteins in a one-step and reagentless fashion. The "open bridge"-like probe can split into two upon ATP-induced cross-linking of hemoglobin to the probe. The covalently captured hemoglobin can subsequently use its peroxidase-like activity to induce a second cross-coupling between the probe and the tissue factor. A fluorescent probe-target covalent complex is formed, enabling thorough rinsing to minimize nonspecific interference. Finally, using hemoglobin's peroxidase activity to improve sensitivity, the assay has been successfully applied in detecting the two proteins in the periphery serum of pregnant women. These results may promise a near future application of the proposed method for providing an early warning for gestational hypoxia and hypertension, particularly under the stress of SARS-Cov-2.

Aspirin alleviates fibronectin-induced preeclampsia phenotypes in a mouse model and reverses fibronectin-mediated trophoblast invasiveness under hypoxia by regulating ciliogenesis and Akt and MAPK signaling

The placenta experiences a low-oxygen stage during early pregnancy. Aspirin is an effective preventative treatment for preeclampsia if applied early in pregnancy. Elevation of fibronectin (FN) level has been reported to be associated with preeclampsia; however, the role of FN in the physiological hypoxic phase and whether aspirin exerts its effect on FN at this hypoxic stage remain unknown. We determined pregnancy outcomes by injecting saline or recombinant FN protein into C57BL/6 pregnant mice and one group of FN-injected mice was fed aspirin. The effects of FN, the underlying pathways on trophoblast biology, and cilia formation under hypoxia were investigated in FN-pretreated or FN-knockdown HTR-8/SVneo cells in a hypoxic chamber (0.1 % O2). Preeclampsia-like phenotypes, including blood pressure elevation and proteinuria, developed in FN-injected pregnant mice. The fetal weight of FN-injected mice was significantly lower than that of non-FN-injected mice (p < 0.005). Trophoblast FN expression was upregulated under hypoxia, which could be suppressed by aspirin treatment. FN inhibited trophoblast invasion and migration under hypoxia, and this inhibitory effect occurred through downregulating ZEB1/2, MMP 9 and the Akt and MAPK signaling pathways. Ciliogenesis of trophoblasts was stimulated under hypoxia but was inhibited by FN treatment. Aspirin was shown to reverse the FN-mediated inhibitory effect on trophoblast invasion/migration and ciliogenesis. In conclusion, FN overexpression induces preeclampsia-like symptoms and impairs fetal growth in mice. Aspirin may exert its suppressive effect on FN upregulation and FN-mediated cell function in the hypoxic stage of pregnancy and therefore provides a preventative effect on preeclampsia development.

Guidelines for assessing maternal cardiovascular physiology during pregnancy and postpartum

Maternal mortality rates are at an all-time high across the world and are set to increase in subsequent years. Cardiovascular disease is the leading cause of death during pregnancy and postpartum, especially in the United States. Therefore, understanding the physiological changes in the cardiovascular system during normal pregnancy is necessary to understand disease-related pathology. Significant systemic and cardiovascular physiological changes occur during pregnancy that are essential for supporting the maternal-fetal dyad. The physiological impact of pregnancy on the cardiovascular system has been examined in both experimental animal models and in humans. However, there is a continued need in this field of study to provide increased rigor and reproducibility. Therefore, these guidelines aim to provide information regarding best practices and recommendations to accurately and rigorously measure cardiovascular physiology during normal and cardiovascular disease-complicated pregnancies in human and animal models.

Placental Methylglyoxal in Preeclampsia: Vascular and Biomarker Implications

BACKGROUND

Preeclampsia is a multifaceted syndrome that includes maternal vascular dysfunction. We hypothesize that increased placental glycolysis and hypoxia in preeclampsia lead to increased levels of methylglyoxal (MGO), consequently causing vascular dysfunction.

METHODS

Plasma samples and placentas were collected from uncomplicated and preeclampsia pregnancies. Uncomplicated placentas and trophoblast cells (BeWo) were exposed to hypoxia. The reactive dicarbonyl MGO and advanced glycation end products (Nε-(carboxymethyl)lysine [CML], Nε-(carboxyethyl)lysine [CEL], and MGO-derived hydroimidazolone [MG-H]) were quantified using liquid chromatography-tandem mass spectrometry. The activity of GLO1 (glyoxalase-1), that is, the enzyme detoxifying MGO, was measured. The impact of MGO on vascular function was evaluated using wire/pressure myography. The therapeutic potential of the MGO-quencher quercetin and mitochondrial-specific antioxidant mitoquinone mesylate (MitoQ) was explored.

RESULTS

MGO, CML, CEL, and MG-H2 levels were elevated in preeclampsia-placentas (+36%, +36%, +25%, and +22%, respectively). Reduced GLO1 activity was observed in preeclampsia-placentas (-12%) and hypoxia-exposed placentas (-16%). Hypoxia-induced MGO accumulation in placentas was mitigated by the MGO-quencher quercetin. Trophoblast cells were identified as the primary source of MGO. Reduced GLO1 activity was also observed in hypoxia-exposed BeWo cells (-26%). Maternal plasma concentrations of CML and the MGO-derived MG-H1 increased as early as 12 weeks of gestation (+16% and +17%, respectively). MGO impaired endothelial barrier function, an effect mitigated by MitoQ, and heightened vascular responsiveness to thromboxane A2.

CONCLUSIONS

This study reveals the accumulation of placental MGO in preeclampsia and upon exposure to hypoxia, demonstrates how MGO can contribute to vascular impairment, and highlights plasma CML and MG-H1 levels as promising early biomarkers for preeclampsia.

Genetic Insights and Neonatal Outcomes in Preeclampsia and Eclampsia: A Detailed Analysis of the RS5707 Genotype

BACKGROUND

Preeclampsia (PE) and eclampsia (E) are severe pregnancy complications with significant maternal and neonatal health impacts. This study explores the association of the rs5707 polymorphism in the renin-angiotensin system (RAS) with PE/E and related neonatal outcomes.

MATERIALS AND METHODS

We conducted a cross-sectional study involving 400 mother-newborn dyads at the "Pius Brinzeu" Emergency Clinical Hospital Timisoara. Participants were divided into a control group (254 normotensive women) and a PE/E group (146 women with PE/E). Genotyping for the rs5707 polymorphism was performed using real-time PCR, and statistical analyses assessed associations with maternal body mass index (BMI) and neonatal outcomes.

RESULTS

The AA genotype of rs5707 was significantly associated with a reduced risk of PE/E and more favorable neonatal outcomes, including higher Apgar scores, greater birth weights, and longer gestational ages. Conversely, the AC genotype correlated with increased maternal BMI and adverse neonatal outcomes. Odds ratios highlighted the protective effect of the AA genotype against PE/E and the increased risk associated with the AC genotype.

CONCLUSIONS

This study revealed the critical role of the rs5707 polymorphism in PE/E development and neonatal health. Genetic screening for rs5707 could enhance early identification and personalized intervention strategies, improving outcomes for both mothers and neonates. Further research is needed to validate these findings across diverse populations and to uncover the underlying mechanisms.

[High-flow nasal oxygen versus conventional oxygen therapy during cesarean section under neuraxial anesthesia in pregnant women with heart disease: a randomized controlled trial]

OBJECTIVE

To evaluate the beneficial effects of high-flow nasal cannula (HFNC) oxygen therapy during cesarean section in pregnant women with heart disease.

METHODS

We conducted a single-center, single-blinded randomized trial of HFNC oxygen therapy in pregnant women with heart disease undergoing cesarean section under neuraxial anesthesia.The participants were randomly assigned to receive either HFNC oxygen therapy with inspiratory flow of 30 L/min with 40% FIO2(n=27) or conventional oxygen therapy (COT) with oxygen flow rate of 5 L/min via a nasal cannula (n=31).The primary outcome was maternal desaturation (SpO2 < 94% lasting more than 3 min or PaO2/FIO2≤300 mmHg).

RESULTS

Maternal desaturation was observed in 7.4%(2/27) of the women in HFNC group and in 32.3%(10/31) in the COT group.None of the cases required tracheal intubation during the perioperative period.The HFNC group had a significantly higher incidence of postoperative leukocytosis (P < 0.05) but without pyrexia or other inflammation-related symptoms.There were no significant differences between the two groups in the secondary maternal outcomes (need for respiratory support, maternal ICU admission, postoperative respiratory complications, and cardiovascular complications) or neonatal outcomes (P>0.05).

CONCLUSION

In pregnant women with heart disease, HFNC therapy can significantly reduce the rate of maternal desaturation during the perioperative period of cesarean section without adverse effects on short-term maternal or fetal outcomes.

Differential proteomics of circulating extracellular vesicles of placental origin isolated from women with early-onset preeclampsia reveal aberrant innate immune and hemostasis processes

PROBLEM

Early-onset preeclampsia (EOPE) is a severe gestational hypertensive disorder with significant feto-maternal morbidity and mortality due to uteroplacental insufficiency. Circulating extracellular vesicles of placental origin (EV-P) are known to be involved in the pathophysiology of EOPE and might serve as an ideal reservoir for its specific biomarkers. Therefore, we aimed to characterize and perform comparative proteomics of circulating EV-P from healthy pregnant and EOPE women before delivery.

METHOD OF STUDY

The EV-P from both groups were isolated using immunoaffinity and were characterized using transmission electron microscopy, dynamic light scattering, nanoparticle tracking analysis, and immunoblotting. Following IgG albumin depletion, the pooled proteins that were isolated from EV-P of both groups were subjected to quantitative TMT proteomics.

RESULTS

Circulating term EV-P isolated from both groups revealed ∼150 nm spherical vesicles containing CD9 and CD63 along with placental PLAP and HLA-G proteins. Additionally, the concentration of EOPE-derived EV-P was significantly increased. A total of 208 proteins were identified, with 26 among them being differentially abundant in EV-P of EOPE women. This study linked the pathophysiology of EOPE to 19 known and seven novel proteins associated with innate immune responses such as complement and TLR signaling along with hemostasis and oxygen homeostasis.

CONCLUSION

The theory suggesting circulating EVs of placental origin could mimic molecular information from the parent organ-"the placenta"-is strengthened by this study. The findings pave the way for possible discovery of novel prognostic and predictive biomarkers as well as provide insight into the mechanisms driving the pathogenesis of EOPE.

Prenatal Hypoxia Triggers a Glucocorticoid-Associated Depressive-like Phenotype in Adult Rats, Accompanied by Reduced Anxiety in Response to Stress

Fetal hypoxia and maternal stress frequently culminate in neuropsychiatric afflictions in life. To replicate this condition, we employed a model of prenatal severe hypoxia (PSH) during days 14-16 of rat gestation. Subsequently, both control and PSH rats at 3 months old were subjected to episodes of inescapable stress to induce learned helplessness (LH). The results of the open field test revealed an inclination towards depressive-like behavior in PSH rats. Following LH episodes, control (but not PSH) rats displayed significant anxiety. LH induced an increase in glucocorticoid receptor (GR) levels in extrahypothalamic brain structures, with enhanced nuclear translocation in the hippocampus (HPC) observed both in control and PSH rats. However, only control rats showed an increase in GR nuclear translocation in the amygdala (AMG). The decreased GR levels in the HPC of PSH rats correlated with elevated levels of hypothalamic corticotropin-releasing hormone (CRH) compared with the controls. However, LH resulted in a reduction of the CRH levels in PSH rats, aligning them with those of control rats, without affecting the latter. This study presents evidence that PSH leads to depressive-like behavior in rats, associated with alterations in the glucocorticoid system. Notably, these impairments also contribute to increased resistance to severe stressors.

Cause of fetal growth restriction during high-altitude pregnancy

High-altitude pregnancy increases the incidence of fetal growth restriction and reduces birth weight. This poses a significant clinical challenge as both are linked to adverse health outcomes, including raised infant mortality and the development of the metabolic syndrome in later life. While this reduction in birth weight is mostly understood to be driven by the hypobaric hypoxia of high altitude, the causative mechanism is unclear. Moreover, it is now recognized that highland ancestry confers protection against this reduction in birth weight. Here, we analyze the evidence that pregnancy at high altitude reduces birth weight and that highland ancestry confers protection, discussing mechanisms contributing to both effects.

In vivo mitochondria-targeted protection against uterine artery vascular dysfunction and remodelling in rodent hypoxic pregnancy

Gestational hypoxia adversely affects uterine artery function, increasing complications. However, an effective therapy remains unidentified. Here, we show in rodent uterine arteries that hypoxic pregnancy promotes hypertrophic remodelling, increases constrictor reactivity via protein kinase C signalling, and triggers compensatory dilatation via nitric oxide-dependent mechanisms and stimulation of large conductance Ca2+ -activated K+ -channels. Maternal in vivo oral treatment with the mitochondria-targeted antioxidant MitoQ in hypoxic pregnancy normalises uterine artery reactivity and prevents vascular remodelling. From days 6-20 of gestation (term ∼22 days), female Wistar rats were randomly assigned to normoxic or hypoxic (13-14% O2 ) pregnancy ± daily maternal MitoQ treatment (500 µm in drinking water). At 20 days of gestation, maternal, placental and fetal tissue was frozen to determine MitoQ uptake. The uterine arteries were harvested and, in one segment, constrictor and dilator reactivity was determined by wire myography. Another segment was fixed for unbiased stereological analysis of vessel morphology. Maternal administration of MitoQ in both normoxic and hypoxic pregnancy crossed the placenta and was present in all tissues analysed. Hypoxia increased uterine artery constrictor responses to norepinephrine, angiotensin II and the protein kinase C activator, phorbol 12,13-dibutyrate. Hypoxia enhanced dilator reactivity to sodium nitroprusside, the large conductance Ca2+ -activated K+ -channel activator NS1619 and ACh via increased nitric oxide-dependent mechanisms. Uterine arteries from hypoxic pregnancy showed increased wall thickness and MitoQ treatment in hypoxic pregnancy prevented all effects on uterine artery reactivity and remodelling. The data support mitochondria-targeted therapy against adverse changes in uterine artery structure and function in high-risk pregnancy. KEY POINTS: Dysfunction and remodelling of the uterine artery are strongly implicated in many pregnancy complications, including advanced maternal age, maternal hypertension of pregnancy, maternal obesity, gestational diabetes and pregnancy at high altitude. Such complications not only have immediate adverse effects on the growth of the fetus, but also they can also increase the risk of cardiovascular disease in the mother and offspring. Despite this, there is a significant unmet clinical need for therapeutics that treat uterine artery vascular dysfunction in adverse pregnancy. Here, we show in a rodent model of gestational hypoxia that in vivo oral treatment of the mitochondria-targeted antioxidant MitoQ protects against uterine artery vascular dysfunction and remodelling, supporting the use of mitochondria-targeted therapy against adverse changes in uterine artery structure and function in high-risk pregnancy.

Genomic Selection Signals in Andean Highlanders Reveal Adaptive Placental Metabolic Phenotypes That Are Disrupted in Preeclampsia

BACKGROUND

The chronic hypoxia of high-altitude residence poses challenges for tissue oxygen supply and metabolism. Exposure to high altitude during pregnancy increases the incidence of hypertensive disorders of pregnancy and fetal growth restriction and alters placental metabolism. High-altitude ancestry protects against altitude-associated fetal growth restriction, indicating hypoxia tolerance that is genetic in nature. Yet, not all babies are protected and placental pathologies associated with fetal growth restriction occur in some Andean highlanders.

METHODS

We examined placental metabolic function in 79 Andeans (18-45 years; 39 preeclamptic and 40 normotensive) living in La Paz, Bolivia (3600-4100 m) delivered by unlabored Cesarean section. Using a selection-nominated approach, we examined links between putatively adaptive genetic variation and phenotypes related to oxygen delivery or placental metabolism.

RESULTS

Mitochondrial oxidative capacity was associated with fetal oxygen delivery in normotensive but not preeclamptic placenta and was also suppressed in term preeclamptic pregnancy. Maternal haplotypes in or within 200 kb of selection-nominated genes were associated with lower placental mitochondrial respiratory capacity (PTPRD [protein tyrosine phosphatase receptor-δ]), lower maternal plasma erythropoietin (CPT2 [carnitine palmitoyl transferase 2], proopiomelanocortin, and DNMT3 [DNA methyltransferase 3]), and lower VEGF (vascular endothelial growth factor) in umbilical venous plasma (TBX5 [T-box transcription factor 5]). A fetal haplotype within 200 kb of CPT2 was associated with increased placental mitochondrial complex II capacity, placental nitrotyrosine, and GLUT4 (glucose transporter type 4) protein expression.

CONCLUSIONS

Our findings reveal novel associations between putatively adaptive gene regions and phenotypes linked to oxygen delivery and placental metabolic function in highland Andeans, suggesting that such effects may be of genetic origin. Our findings also demonstrate maladaptive metabolic mechanisms in the context of preeclampsia, including dysregulation of placental oxygen consumption.

Evidence for hypoxia-induced dysregulated cholesterol homeostasis in preeclampsia: Insights into the mechanisms from human placental cells and tissues

Preeclampsia (PE) poses a considerable risk to the long-term cardiovascular health of both mothers and their offspring due to a hypoxic environment in the placenta leading to reduced fetal oxygen supply. Cholesterol is vital for fetal development by influencing placental function. Recent findings suggest an association between hypoxia, disturbed cholesterol homeostasis, and PE. This study investigates the influence of hypoxia on placental cholesterol homeostasis. Using primary human trophoblast cells and placentae from women with PE, various aspects of cholesterol homeostasis were examined under hypoxic and hypoxia/reoxygenation (H/R) conditions. Under hypoxia and H/R, intracellular total and non-esterified cholesterol levels were significantly increased. This coincided with an upregulation of HMG-CoA-reductase and HMG-CoA-synthase (key genes regulating cholesterol biosynthesis), and a decrease in acetyl-CoA-acetyltransferase-1 (ACAT1), which mediates cholesterol esterification. Hypoxia and H/R also increased the intracellular levels of reactive oxygen species and elevated the expression of hypoxia-inducible factor (HIF)-2α and sterol-regulatory-element-binding-protein (SREBP) transcription factors. Additionally, exposure of trophoblasts to hypoxia and H/R resulted in enhanced cholesterol efflux to maternal and fetal serum. This was accompanied by an increased expression of proteins involved in cholesterol transport such as the scavenger receptor class B type I (SR-BI) and the ATP-binding cassette transporter G1 (ABCG1). Despite these metabolic alterations, mitogen-activated-protein-kinase (MAPK) signaling, a key regulator of cholesterol homeostasis, was largely unaffected. Our findings indicate dysregulation of cholesterol homeostasis at multiple metabolic points in both the trophoblast hypoxia model and placentae from women with PE. The increased cholesterol efflux and intracellular accumulation of non-esterified cholesterol may have critical implications for both the mother and the fetus during pregnancy, potentially contributing to an elevated cardiovascular risk later in life.

The Prenatal Hypoxic Pathology Associated with Maternal Stress Predisposes to Dysregulated Expression of the chrna7 Gene and the Subsequent Development of Nicotine Addiction in Adult Offspring

INTRODUCTION

Previous studies have shown that fetal hypoxia predisposes individuals to develop addictive disorders in adulthood. However, the specific impact of maternal stress, mediated through glucocorticoids and often coexisting with fetal hypoxia, is not yet fully comprehended.

METHODS

To delineate the potential effects of these pathological factors, we designed models of prenatal severe hypoxia (PSH) in conjunction with maternal stress and prenatal intrauterine ischemia (PII). We assessed the suitability of these models for our research objectives by measuring HIF1α levels and evaluating the glucocorticoid neuroendocrine system. To ascertain nicotine dependence, we employed the conditioned place aversion test and the startle response test. To identify the key factor implicated in nicotine addiction associated with PSH, we employed techniques such as Western blot, immunohistochemistry, and correlational analysis between chrna7 and nr3c1 genes across different brain structures.

RESULTS

In adult rats exposed to PSH and PII, we observed increased levels of HIF1α in the hippocampus (HPC). However, the PSH group alone exhibited reduced glucocorticoid receptor levels and disturbed circadian glucocorticoid rhythms. Additionally, they displayed signs of nicotine addiction in the conditioned place aversion and startle response tests. We also observed elevated levels of phosphorylated DARPP-32 protein in the nucleus accumbens (NAc) indicated compromised glutamatergic efferent signaling. Furthermore, there was reduced expression of α7 nAChR, which modulates glutamate release, in the medial prefrontal cortex (PFC) and HPC. Correlation analysis revealed strong associations between chrna7 and nr3c1 expression in both brain structures.

CONCLUSION

Perturbations in the glucocorticoid neuroendocrine system and glucocorticoid-dependent gene expression of chrna7 associated with maternal stress response to hypoxia in prenatal period favor the development of nicotine addiction in adulthood.

CoCl2-mimicked Hypoxia Induces the Assembly of Stress Granules in Trophoblast Cells Via eIF2α Phosphorylation-dependent and - Independent Pathways

INTRODUCTION

Hypoxia has been implicated in preeclampsia (PE) pathophysiology. Stress granules (SGs) are present in the placenta of patients with PE. However, the pathways that contribute to SG aggregation in PE remain poorly understood.

OBJECTIVE

The objective of the current study is to investigate this issue.

METHODS

We first established an in vitro hypoxia model using human trophoblast cell line HTR-8/SVneo treated with cobalt chloride (CoCl2). CCK8 assay and wound healing assay were conducted to assess the viability and migration of HTR-8/SVneo cells after exposure to CoCl2-mimicked hypoxia. SG component expression in HTR-8/SVneo cells treated with CoCl2 alone, or in combination with indicated siRNAs was evaluated by reverse transcription quantitative PCR (RT-qPCR), western blot and immunofluorescence staining.

RESULTS

Our results found CoCl2-mimicked hypoxia inhibits the proliferation and migration of HTR-8/SVneo cells. The treatment of CoCl2 can induce SG assembly in HTR-8/Svneo cells. Mechanistically, both heme-regulated inhibitors (HRI) mediated eukaryotic translation initiation factor (eIF)2α phosphorylation pathway and 4E binding protein 1 (4EBP1) pathway are involved in SG formation under the stress of CoCl2- mimicked hypoxia.

CONCLUSION

Hypoxia-induced SGs in trophoblast cells might contribute to the etiology of PE.

The role of maternal hormones in regulating autonomic functions during pregnancy

Offspring development relies on numerous physiological changes that occur in a mother's body, with hormones driving many of these adaptations. Amongst these, the physiological functions controlled by the autonomic nervous system are required for the mother to survive and are adjusted to meet the demands of the growing foetus and to ensure a successful birth. The hormones oestrogen, progesterone, and lactogenic hormones rise significantly during pregnancy, suggesting they may also play a role in regulating the maternal adaptations linked to autonomic nervous system functions, including respiratory, cardiovascular, and thermoregulatory functions. Indeed, expression of pregnancy hormone receptors spans multiple brain regions known to regulate these physiological functions. This review examines how respiratory, cardiovascular, and thermoregulatory functions are controlled by these pregnancy hormones by focusing on their action on central nervous system circuits. Inadequate adaptations in these systems during pregnancy can give rise to several pregnancy complications, highlighting the importance in understanding the mechanistic underpinnings of these changes and potentially identifying ways to treat pregnancy-associated afflictions using hormones.

Hypoxia Inducible Factors (HIF1α and HIF3α) are differentially methylated in preeclampsia placentae and are associated with birth outcomes

Preeclampsia is a placental vascular pathology and hypoxia is known to influence placental angiogenesis. Hypoxia Inducible Factors (HIF1α and HIF3α) mediate the response to cellular oxygen concentration and bind to hypoxia response element of target genes. However the mechanism regulating above activity is not well-understood. We investigated if placental DNA methylation (DNAm) and expression of HIF1α and 3α genes are altered and associated with pre-eclampsia, placental weight and birth outcomes. Using a cohort comprising women with preeclampsia [N = 100, delivering at term (N = 43) and preterm (N = 57)] and normotensive controls (N = 100), we analysed DNAm in HIF1α and 3α, and their mRNA expression in placentae, employing pyrosequencing and quantitative real-time PCR, respectively. We observed significant hypermethylation at cg22891070 of HIF3α in preeclampsia placentae compared to controls (β = 1.5%, p = 0.04). CpG8 in the promoter region of HIF1α, showed marginally significant hypomethylation in preterm preeclampsia compared to controls (β = - 0.15%, p = 0.055). HIF1α expression was significantly lower in preterm preeclampsia compared to controls (mean ± SE = 10.16 ± 2.00 vs 4.25 ± 0.90, p = 0.04). Further, DNAm in HIF1α promoter region was negatively associated with its expression levels (β =  - 0.165, p = 0.024). Several CpGs in HIF1α were negatively associated with placental weight and birth outcomes including birth weight (β range =  - 0.224-0.300) and birth length [β range =  - 0.248 to - 0.301 (p < 0.05 for all)]. Overall, we demonstrate altered DNAm in HIF1α and HIF3α in preeclampsia placentae, also associated with various birth outcomes. Correlation of DNAm in HIF1α and its expression suggests a possible role in the pathogenesis of pre-eclampsia. Further investigations on interactions between HIF1α and HIF3α in preeclampsia would be interesting.

GPR65 inhibits human trophoblast cell adhesion through upregulation of MYLK and downregulation of fibronectin via cAMP-ERK signaling in a low pH environment

BACKGROUND

Extravillous trophoblasts (EVTs) are essential cells during the formation of the placenta, with the major function of invading the maternal decidua, anchoring the developing placenta to the uterus, remodeling uterine arteries, and regulating immune responses to prevent rejection. During early pregnancy, the decidua undergoes a hypoxic and acidic microenvironment, which has been shown to participate in tumor cell migration, invasion, growth, and angiogenesis. Nevertheless, the mechanisms by which EVTs sense and respond to the acidic microenvironment, thereby executing their functions, remain poorly understood.

METHODS

The effects of G protein-coupled receptor 65 (GPR65) on cell adhesion and other cellular functions were tested using JAR spheroids, mouse blastocysts, and HTR-8/SVneo cells. Specifically, we employed HTR-8/SVneo cells for gene overexpression and silencing to investigate the underlying mechanism of GPR65's impact on trophoblast cell function under acidic conditions. Additionally, villus tissue samples obtained from early pregnancy loss patients were utilized to explore the potential association between GPR65 and its related signaling pathway molecules with the disease.

RESULTS

This study identified GPR65 expression widely in trophoblasts, with the highest level in EVTs. Importantly, optimal GPR65 levels are required for maintaining normal adhesion, migration, and invasion, whereas overexpression of GPR65 inhibits these functions by activating the cAMP-ERK signaling pathway, upregulating myosin light chain kinase (MYLK) and MYLK3 expression, and subsequently downregulating fibronectin. Consistently, elevated expression of GPR65, MYLK, and MYLK3 is observed in patients suffering from early pregnancy loss.

CONCLUSIONS

This work offers insights into the suppressive effects of GPR65 on EVT function under acidic conditions and highlights a putative target for therapeutic intervention in early pregnancy complications. Video Abstract.

Necroptosis in the pathophysiology of preeclampsia

Necroptosis is a newly-identified form of gene-regulated cell necrosis that is increasingly considered to be a pathway associated with human pathophysiological conditions. Cells undergoing necroptosis exhibit necrotic phenotypes, including disruption of the plasma membrane integrity, organelle swelling, and cytolysis. Accumulating evidence suggests that trophoblast necroptosis plays a complex role in preeclampsia (PE). However, the exact pathogenesis remains unclear. Its unique mechanisms of action in various diseases are expected to provide prospects for the treatment of PE. Therefore, it is necessary to further explore its molecular mechanism in PE in order to identify potential therapeutic options. This review examines the current knowledge regarding the role and mechanisms of necroptosis in PE and provides a theoretical basis for new therapeutic targets for PE.

The effects of COVID-19 on placental morphology

The impact of the COVID-19 infection, caused by Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), during the pandemic has been considerably more severe in pregnant women than non-pregnant women. Therefore, a review detailing the morphological alterations and physiological changes associated with COVID-19 during pregnancy and the effect that these changes have on the feto-placental unit is of high priority. This knowledge is crucial for these mothers, their babies and clinicians to ensure a healthy life post-pandemic. Hence, we review the placental morphological changes due to COVID-19 to enhance the general understanding of how pregnant mothers, their placentas and unborn children may have been affected by this pandemic. Based on current literature, we deduced that COVID-19 pregnancies were oxygen deficient, which could further result in other pregnancy-related complications like preeclampsia and IUGR. Therefore, we present an up-to-date review of the COVID-19 pathophysiological implications on the placenta, covering the function of the placenta in COVID-19, the effects of this virus on the placenta, its functions and its link to other gestational complications. Furthermore, we highlight the possible effects of COVID-19 therapeutic interventions on pregnant mothers and their unborn children. Based on the literature, we strongly suggest that consistent surveillance for the mothers and infants from COVID-19 pregnancies be prioritised in the future. Though the pandemic is now in the past, its effects are long-term, necessitating the monitoring of clinical manifestations in the near future.

SIRTUINS MODULATORS COUNTERACT MITOCHONDRIAL DYSFUNCTION IN CELLULAR MODELS OF HYPOXIA: RELEVANCE TO SCHIZOPHRENIA

Schizophrenia (SZ) is a neurodevelopmental-associated disorder strongly related to environmental factors, such as hypoxia. Because there is no cure for SZ or any pharmacological approach that could revert hypoxia-induced cellular damages, we evaluated whether modulators of sirtuins could abrogate hypoxia-induced mitochondrial deregulation as a neuroprotective strategy. Firstly, astrocytes from control (Wistar) and Spontaneously Hypertensive Rats (SHR), a model of both SZ and neonatal hypoxia, were submitted to chemical hypoxia. Then, cells were exposed to different concentrations of Nicotinamide (NAM), Resveratrol (Resv), and Sirtinol (Sir) for 48hrs. Our data indicate that sirtuins modulation reduces cell death increasing the acetylation of histone 3. This outcome is related to the rescue of loss of mitochondrial membrane potential, changes in mitochondrial calcium buffering capacity, decreased O₂^-• levels and increased expression of metabolic regulators (Nrf-1 and Nfe2l2) and mitochondrial content. Such findings are relevant not only for hypoxia-associated conditions, named pre-eclampsia but also for SZ since prenatal hypoxia is a relevant environmental factor related to this burdensome neuropsychiatric disorder.

TET2 confers a mechanistic link of microRNA-210 and mtROS in hypoxia-suppressed spontaneous transient outward currents in uterine arteries of pregnant sheep

Hypoxia during pregnancy impairs uterine vascular adaptation via microRNA-210 (miR-210)-mediated mitochondrial dysfunction and mitochondrial reactive oxygen species (mtROS) generation. TET methylcytosine dioxygenase 2 (TET2) participates in regulating inflammation and oxidative stress and its deficiency contributes to the pathogenesis of multiple cardiovascular diseases. Thus, we hypothesize a role of TET2 in hypoxia/miR-210-mediated mtROS suppressing spontaneous transient outward currents (STOCs) in uterine arteries. We found that gestational hypoxia downregulated TET2 in uterine arteries of pregnant sheep and TET2 was a target of miR-210. Knockdown of TET2 with small interfering RNAs suppressed mitochondrial respiration, increased mtROS, inhibited STOCs and elevated myogenic tone. By contrast, overexpression of TET2 negated hypoxia- and miR-210-induced mtROS. The effects of TET2 knockdown in uterine arteries on mtROS, STOCs and myogenic contractions were blocked by the mitochondria-targeted antioxidant MitoQ. In addition, the recovery effects of inhibiting endogenous miR-210 with miR-210-LNA on hypoxia-induced suppression of STOCs and augmentation of myogenic tone were reversed by TET2 knockdown in uterine arteries. Together, our study reveals a novel mechanistic link between the miR-210-TET2-mtROS pathway and inhibition of STOCs and provides new insights into the understanding of uterine vascular maladaptation in pregnancy complications associated with gestational hypoxia. KEY POINTS: Gestational hypoxia downregulates TET methylcytosine dioxygenase 2 (TET2) in uterine arteries of pregnant sheep. TET2 is a downstream target of microRNA-210 (miR-210) and miR-210 mediates hypoxia-induced TET2 downregulation. Knockdown of TET2 in uterine arteries recapitulates the effect of hypoxia and miR-210 and impairs mitochondrial bioenergetics and increases mitochondrial reactive oxygen species (mtROS) . Overexpression of TET2 negates the effect of hypoxia and miR-210 on increasing mtROS. TET2 knockdown reiterates the effect of hypoxia and miR-210 and suppresses spontaneous transient outward currents (STOCs) and elevates myogenic tone, and these effects are blocked by MitoQ. Knockdown of TET2 reverses the miR-210-LNA-induced reversal of the effects of hypoxia on STOCs and myogenic tone in uterine arteries.

Elevation of Pulmonary Artery Pressure in Newborns from High-Altitude Pregnancies Complicated by Preeclampsia

We hypothesized that fetal exposure to the oxidative stress induced by the combined challenge of preeclampsia (PE) and high altitude would induce a significant impairment in the development of pulmonary circulation. We conducted a prospective study in La Paz (Bolivia, mean altitude 3625 m) in which newborns from singleton pregnancies with and without PE were compared (PE group n = 69, control n = 70). We conducted an echocardiographic study in these infants at the median age of two days. The percentage of cesarean deliveries and small for gestational age (SGA) infants was significantly higher in the PE group. Heart rate, respiratory rate, and oxygen saturation did not vary significantly between groups. Estimated pulmonary arterial pressure and pulmonary vascular resistance were 30% higher in newborns exposed to PE and high altitude compared with those exposed only to high altitude. We also detected signs of right ventricular hypertrophy in infants subjected to both exposures. In conclusion, this study provides evidence that the combination of PE and pregnancy at high altitude induces subclinical alterations in the pulmonary circulation of the newborn. Follow-up of this cohort may provide us with valuable information on the potential increased susceptibility to developing pulmonary hypertension or other pulmonary and cardiovascular disorders.

Oxidative Regulation of Vascular Cav1.2 Channels Triggers Vascular Dysfunction in Hypertension-Related Disorders

Blood pressure is determined by cardiac output and peripheral vascular resistance. The L-type voltage-gated Ca²⁺ (Ca_v1.2) channel in small arteries and arterioles plays an essential role in regulating Ca²⁺ influx, vascular resistance, and blood pressure. Hypertension and preeclampsia are characterized by high blood pressure. In addition, diabetes has a high prevalence of hypertension. The etiology of these disorders remains elusive, involving the complex interplay of environmental and genetic factors. Common to these disorders are oxidative stress and vascular dysfunction. Reactive oxygen species (ROS) derived from NADPH oxidases (NOXs) and mitochondria are primary sources of vascular oxidative stress, whereas dysfunction of the Ca_v1.2 channel confers increased vascular resistance in hypertension. This review will discuss the importance of ROS derived from NOXs and mitochondria in regulating vascular Ca_v1.2 and potential roles of ROS-mediated Ca_v1.2 dysfunction in aberrant vascular function in hypertension, diabetes, and preeclampsia.

Abnormal cerebral microvascular perfusion and reactivity in female offspring of reduced uterine perfusion pressure (RUPP) mice model

Children born from women with preeclampsia have alterations in cerebral neurovascular development and a high risk for developing cognitive alterations. Because cerebral blood vessels are critical components in cerebrovascular development, we evaluated the brain microvascular perfusion and microvascular reactivity (exposed to external stimuli of warm and cold) in pups born to preeclampsia-like syndrome based on the reduction of uterine perfusion (RUPP). Also, we evaluate the angiogenic proteomic profile in those brains. Pregnant mice showed a reduction in uterine flow after RUPP surgery (-40 to 50%) associated with unfavorable perinatal results compared to sham mice. Furthermore, offspring of the RUPP mice exhibited reduced brain microvascular perfusion at postnatal day 5 (P5) compared with offspring from sham mice. This reduction was preferentially observed in females. Also, brain microvascular reactivity to external stimuli (warm and cold) was reduced in pups of RUPP mice. Furthermore, a differential expression of the angiogenic profile associated with inflammation, extrinsic apoptotic, cancer, and cellular senescence processes as the primary signaling impaired process was found in the brains of RUPP-offspring. Then, offspring (P5) from preeclampsia-like syndrome exhibit impaired brain perfusion and microvascular reactivity, particularly in female mice, associated with differential expression of angiogenic proteins in the brain tissue.

Maternal obesity: new placental paradigms unfolded

The prevalence of maternal obesity is increasing at an alarming rate, and is providing a major challenge for obstetric practice. Adverse effects on maternal and fetal health are mediated by complex interactions between metabolic, inflammatory, and oxidative stress signaling in the placenta. Endoplasmic reticulum (ER) stress and activation of the unfolded protein response (UPR) are common downstream pathways of cell stress, and there is evidence that this conserved homeostatic response may be a key mediator in the pathogenesis of placental dysfunction. We summarize the current literature on the placental cellular and molecular changes that occur in obese women. A special focus is cast onto placental ER stress in obese pregnancy, which may provide a novel link for future investigation.

Gestational hypoxia in late pregnancy differentially programs subcortical brain maturation in male and female rat offspring

BACKGROUND

Hypoxia is associated with pregnancy complications, such as preeclampsia, placental abruption, and gestational sleep apnea. Hypoxic insults during gestation can impact the brain maturation of cortical and subcortical pathways, such as the nigrostriatal pathway. However, the long-term effects of in utero hypoxic stress exposure on brain maturation in offspring are unclear, especially exposure during late gestation. The purpose of this study was to determine the impact of gestational hypoxia in late pregnancy on developmental programming of subcortical brain maturation by focusing on the nigrostriatal pathway.

METHODS

Timed pregnant Long-Evans rats were exposed to chronic intermittent hypoxia or room air normoxia from gestational day (GD) 15-19 (term 22-23 days). Male and female offspring were assessed during two critical periods: puberty from postnatal day (PND) 40-45 or young adulthood (PND 60-65). Brain maturation was quantified by examining (1) the structural development of the nigrostriatal pathway via analysis of locomotor behaviors and the substantia nigra dopaminergic neuronal cell bodies and (2) the refinement of the nigrostriatal pathway by quantifying ultrasonic vocalizations (USVs).

RESULTS

The major findings of this study are gestational hypoxia has age- and sex-dependent effects on subcortical brain maturation in offspring by adversely impacting the refinement of the nigrostriatal pathway in the absence of any effects on the structural development of the pathway. During puberty, female offspring were impacted more than male offspring, as evidenced by decreased USV call frequency, chirp USV call duration, and simple call frequency. In contrast, male offspring were impacted more than female offspring during young adulthood, as evidenced by increased latency to first USV, decreased simple USV call intensity, and increased harmonic USV call bandwidth. No effects of gestational hypoxia on the structural development of the nigrostriatal pathway were observed.

CONCLUSIONS

These novel findings demonstrate hypoxic insults during pregnancy mediate developmental programming of the cortical and subcortical pathways, in which male offspring exhibit long-term adverse effects compared to female offspring. Impairment of cortical and subcortical pathways maturation, such as the nigrostriatal pathway, may increase risk for neuropsychiatric disorders (e.g., mood disorders, cognitive dysfunction, brain connectivity dysfunction).

MicroRNA-210-mediated mitochondrial reactive oxygen species confer hypoxia-induced suppression of spontaneous transient outward currents in ovine uterine arteries

Background and Purpose

Hypoxia during pregnancy is associated with increased uterine vascular resistance and elevated blood pressure both in women and female sheep. A previous study demonstrated a causal role of microRNA‐210 (miR‐210) in gestational hypoxia‐induced suppression of Ca²⁺ sparks/spontaneous transient outward currents (STOCs) in ovine uterine arteries, but the underlying mechanisms remain undetermined. We tested the hypothesis that miR‐210 perturbs mitochondrial metabolism and increases mitochondrial reactive oxygen species (mtROS) that confer hypoxia‐induced suppression of STOCs in uterine arteries.

Experimental Approach

Resistance‐sized uterine arteries were isolated from near‐term pregnant sheep and were treated ex vivo in normoxia and hypoxia (10.5% O₂) for 48 h.

Key Results

Hypoxia increased mtROS and suppressed mitochondrial respiration in uterine arteries, which were also produced by miR‐210 mimic to normoxic arteries and blocked by antagomir miR‐210‐LNA in hypoxic arteries. Hypoxia or miR‐210 mimic inhibited Ca²⁺ sparks/STOCs and increased uterine arterial myogenic tone, which were inhibited by the mitochondria‐targeted antioxidant MitoQ. Hypoxia and miR‐210 down‐regulated iron–sulfur cluster scaffold protein (ISCU) in uterine arteries and knockdown of ISCU via siRNAs suppressed mitochondrial respiration, increased mtROS, and inhibited STOCs. In addition, blockade of mitochondrial electron transport chain with antimycin and rotenone inhibited large‐conductance Ca²⁺‐activated K⁺ channels, decreased STOCs and increased uterine arterial myogenic tone.

Conclusion and Implications

This study demonstrates a novel mechanistic role for the miR‐210‐ISCU‐mtROS axis in inhibiting Ca²⁺ sparks/STOCs in the maladaptation of uterine arteries and provides new insights into the understanding of mitochondrial perturbations in the pathogenesis of pregnancy complications resulted from hypoxia.

Impairment of mitochondrial respiration in platelets and placentas: a pilot study in preeclamptic pregnancies

Preeclampsia (PE) is a major complication of pregnancy with partially elucidated pathophysiology. Placental mitochondrial dysfunction has been increasingly studied as major pathomechanism in both early- and late-onset PE. Impairment of mitochondrial respiration in platelets has recently emerged as a peripheral biomarker that may mirror organ mitochondrial dysfunction in several acute and chronic pathologies. The present study was purported to assess mitochondrial respiratory dys/function in both platelets and placental mitochondria in PE pregnancies. To this aim, a high-resolution respirometry SUIT (Substrate-Uncoupler-Inhibitor-Titration) protocol was adapted to assess complex I (glutamate + malate)- and complex II (succinate)-supported respiration. A decrease in all respiratory parameters (basal, coupled, and maximal uncoupled respiration) in peripheral platelets was found in preeclamptic as compared to healthy pregnancies. At variance, placental mitochondria showed a dichotomous behavior in preeclampsia in relation to the fetal birth weight. PE pregnancies with fetal growth restriction were associated with decreased in coupled respiration (oxidative phosphorylation/OXPHOS capacity) and maximal uncoupled respiration (electron transfer/ET capacity). At variance, these respiratory parameters were increased for both complex I- and II-supported respiration in PE pregnancies with normal weight fetuses. Large randomized controlled clinical studies are needed in order to advance our understanding of mitochondrial adaptive vs. pathological changes in preeclampsia.

Chronic Hypoxia in Ovine Pregnancy Recapitulates Physiological and Molecular Markers of Preeclampsia in the Mother, Placenta, and Offspring

BACKGROUND

Preeclampsia continues to be a prevalent pregnancy complication and underlying mechanisms remain controversial. A common feature of preeclampsia is utero-placenta hypoxia. In contrast to the impact of hypoxia on the placenta and fetus, comparatively little is known about the maternal physiology.

METHODS

We adopted an integrative approach to investigate the inter-relationship between chronic hypoxia during pregnancy with maternal, placental, and fetal outcomes, common in preeclampsia. We exploited a novel technique using isobaric hypoxic chambers and in vivo continuous cardiovascular recording technology for measurement of blood pressure in sheep and studied the placental stress in response to hypoxia at cellular and subcellular levels.

RESULTS

Chronic hypoxia in ovine pregnancy promoted fetal growth restriction (FGR) with evidence of fetal brain-sparing, increased placental hypoxia-mediated oxidative damage, and activated placental stress response pathways. These changes were linked with dilation of the placental endoplasmic reticulum (ER) cisternae and increased placental expression of the antiangiogenic factors sFlt-1 (soluble fms-like tyrosine kinase 1) and sEng (soluble endoglin), combined with a shift towards an angiogenic imbalance in the maternal circulation. Chronic hypoxia further led to an increase in uteroplacental vascular resistance and the fall in maternal blood pressure with advancing gestation measured in normoxic pregnancy did not occur in hypoxic pregnancy.

CONCLUSIONS

Therefore, we show in an ovine model of sea-level adverse pregnancy that chronic hypoxia recapitulates physiological and molecular features of preeclampsia in the mother, placenta, and offspring.

Hypoxia induced-disruption of lncRNA TUG1/PRC2 interaction impairs human trophoblast invasion through epigenetically activating Nodal/ALK7 signalling

Inadequate trophoblastic invasion is considered as one of hallmarks of preeclampsia (PE), which is characterized by newly onset of hypertension (>140/90 mmHg) and proteinuria (>300 mg in a 24‐h urine) after 20 weeks of gestation. Accumulating evidence has indicated that long noncoding RNAs are aberrantly expressed in PE, whereas detailed mechanisms are unknown. In the present study, we showed that lncRNA Taurine upregulated 1 (TUG1) were downregulated in preeclamptic placenta and in HTR8/SVneo cells under hypoxic conditions, together with reduced enhancer of zeste homolog2 (EZH2) and embryonic ectoderm development (EED) expression, major components of polycomb repressive complex 2 (PRC2), as well as activation of Nodal/ALK7 signalling pathway. Mechanistically, we found that TUG1 bound to PRC2 (EZH2/EED) in HTR8/SVneo cells and weakened TUG1/PRC2 interplay was correlated with upregulation of Nodal expression via decreasing H3K27me3 mark at the promoter region of Nodal gene under hypoxic conditions. And activation of Nodal signalling prohibited trophoblast invasion via reducing MMP2 levels. Overexpression of TUG1 or EZH2 significantly attenuated hypoxia‐induced reduction of trophoblastic invasiveness via negative modulating Nodal/ALK7 signalling and rescuing expression of its downstream target MMP2. These investigations might provide some evidence for novel mechanisms responsible for inadequate trophoblastic invasion and might shed some light on identifying future therapeutic targets for PE.

Hypoxia regulates fibrosis-related genes via histone lactylation in the placentas of patients with preeclampsia

BACKGROUND

Histone lactylation, a novel epigenetic modification induced by hypoxia and lactate, plays an important role in regulating gene expression. However, the role of histone lactylation in the pathogenesis of preeclampsia remains unknown.

METHODS

Placentas from preeclamptic patients and control pregnant women were collected for protein immunoassay to detect the expression level of histone lactylation, and two trophoblast cell lines were used to simulate the effect of histone lactylation on genes.

RESULTS

We found that lactate and histone lactylation levels were increased in preeclamptic placentas. In vitro, hypoxia was demonstrated to induce histone lactylation by promoting the production of lactate in human-trophoblast-derived cell line (HTR-8/SVneo) and human first-trimester extravillous trophoblast cell line (TEV-1) cells. In addition, 152 genes were found to be upregulated by both hypoxia exposure and sodium l-lactate treatment in HTR-8/SVneo cells. These genes were mainly enriched in the pathways including the response to hypoxia, cell migration and focal adhesion. Among the 152 genes, nine were upregulated in preeclamptic placentas. Most noteworthy, two upregulated fibrosis-related genes, FN1 and SERPINE1, were promoted by hypoxia through histone lactylation mediated by the production of lactate.

CONCLUSIONS

The present study demonstrated the elevated levels of histone lactylation in preeclamptic placentas and identified fibrosis-related genes that were promoted by histone lactylation induced by hypoxia in trophoblast cells, which provides novel insights into the mechanism of placental dysfunction in preeclampsia.

Iron Metabolism in Normal and Pathological Pregnancies and Fetal Consequences

Iron is required for energy production, DNA synthesis, and cell proliferation, mainly as a component of the prosthetic group in hemoproteins and as part of iron-sulfur clusters. Iron is also a critical component of hemoglobin and plays an important role in oxygen delivery. Imbalances in iron metabolism negatively affect these vital functions. As the crucial barrier between the fetus and the mother, the placenta plays a pivotal role in iron metabolism during pregnancy. Iron deficiency affects 1.2 billion individuals worldwide. Pregnant women are at high risk of developing or worsening iron deficiency. On the contrary, in frequent hemoglobin diseases, such as sickle-cell disease and thalassemia, iron overload is observed. Both iron deficiency and iron overload can affect neonatal development. This review aims to provide an update on our current knowledge on iron and heme metabolism in normal and pathological pregnancies. The main molecular actors in human placental iron metabolism are described, focusing on the impact of iron deficiency and hemoglobin diseases on the placenta, together with normal metabolism. Then, we discuss data concerning iron metabolism in frequent pathological pregnancies to complete the picture, focusing on the most frequent diseases.

Preeclampsia and Fetal Congenital Heart Defects

Endothelial dysfunction, impaired implantation and placental insufficiency have been identified as mechanisms behind the development of pre-eclampsia, resulting in angiogenic factors' alteration. Angiogenic imbalance is also associated with congenital heart defects, and this common physiologic pathway may explain the association between them and pre-eclampsia. This review aims to understand the physiology shared by these two entities and whether women with pre-eclampsia have an increased risk of fetal congenital heart defects (or the opposite). The present research has highlighted multiple vasculogenic pathways associated with heart defects and preeclampsia, but also epigenetic and environmental factors, contributing both. It is also known that fetuses with a prenatal diagnosis of congenital heart disease have an increased risk of several comorbidities, including intrauterine growth restriction. Moreover, the impact of pre-eclampsia goes beyond pregnancy as it increases the risk for following pregnancies and for diseases later in life in both offspring and mothers. Given the morbidity and mortality associated with these conditions, it is of foremost importance to understand how they are related and its causative mechanisms. This knowledge may allow earlier diagnosis, an adequate surveillance or even the implementation of preventive strategies.

Role of GRK2 in Trophoblast Necroptosis and Spiral Artery Remodeling: Implications for Preeclampsia Pathogenesis

Impaired invasion of extravillous trophoblasts and severe oxidative stress manifest the poor placentation in preeclampsia, which is life-threatening and more than a hypertensive disease of pregnancy. Previous studies have reported that G protein-coupled receptor kinases (GRKs) play a key role in initiating hypertension and hypertensive renal damage, yet little evidence so far suggests a link between GRKs and preeclampsia-related hypertension. Here, we demonstrate GRK2 expression is significantly downregulated (P < 0.0001) in preeclamptic placentae compared to normotensive controls. Knockdown or inhibition of GRK2 in placentae caused insufficient arterial remodeling and elevated trophoblast necroptosis in vivo. These further induced preeclampsia-like phenotype in mice: hypertension, proteinuria, and elevated pro-angiogenic cytokines. By human extra-villous invasive trophoblast cell line (HTR8/SVneo cells), we revealed the knockdown or inhibition of GRK2 triggered excessive death with typical necroptotic characteristics: nuclear envelope rupture and the activation of RIPK1, RIPK3, and MLKL. Necrostatin-1, an inhibitor of RIPK1, is able to restore the survival of trophoblasts. Together, our findings demonstrated that insufficient GRK2 activity compromises spiral artery remodeling and initiates necrotic events in placentae, thereby leading to preeclampsia. These findings advance our understanding of GRK2 in the pathogenesis of preeclampsia and could shed light on a potential treatment for preeclampsia.

Irisin Protects the Human Placenta from Oxidative Stress and Apoptosis via Activation of the Akt Signaling Pathway

Irisin is a newly discovered exercise-mediated polypeptide hormone. Irisin levels increase during pregnancy however, women with preeclampsia (PE) have significantly lower levels of Irisin compared to women of healthy pregnancies. Even though many studies suggest a role of Irisin in pregnancy, its function in the human placenta is unclear. In the current study, we aimed to understand key roles of Irisin through its ability to protect against apoptosis is the preeclamptic placenta and in ex vivo and in vitro models of hypoxia/re-oxygenation (H/R) injury. Our studies show that Irisin prevents cell death by reducing pro-apoptotic signaling cascades, reducing cleavage of PARP to induce DNA repair pathways and reducing activity of Caspase 3. Irisin caused an increase in the levels of anti-apoptotic BCL2 to pro-apoptotic BAX and reduced ROS levels in an in vitro model of placental ischemia. Furthermore, we show that Irisin treatment acts through the Akt signaling pathway to prevent apoptosis and enhance cell survival. Our findings provide a novel understanding for the anti-apoptotic and pro-survival properties of Irisin in the human placenta under pathological conditions. This work yields new insights into placental development and disease and points towards intervention strategies for placental insufficiencies, such as PE, by protecting and maintaining placental function through inhibiting hypoxic ischemia-induced apoptosis.

Links Between Maternal Cardiovascular Disease and the Health of Offspring

Maternal cardiovascular disease (CVD) during pregnancy is on the rise worldwide, as both more women with congenital heart disease are reaching childbearing age, and conditions such as diabetes, hypertension, and obesity are becoming more prevalent. However, the extent to which maternal CVD influences offspring health, as a neonate and later in childhood and adolescence, remains to be fully understood. The thrifty phenotype hypothesis, by which a fetus adapts to maternal and placental changes to survive a nutrient-starved environment, may provide an answer to the mechanism of maternal CVD and its impact on the offspring. In this narrative review, we aim to provide a review of the literature pertaining to the impact of maternal cardiovascular and hypertensive disease on the health of neonates, children, and adolescents. This review demonstrates that maternal CVD leads to higher rates of complications among neonates. Ultimately, our review supports the hypothesis that maternal CVD leads to intrauterine growth restriction (IUGR), which, through the thrifty phenotype hypothesis and vascular remodelling, can have health repercussions, including an impact on CVD risk, both in the immediate newborn period as well as later throughout the life of the offspring. Further research remains crucial in elucidating the mechanism of maternal CVD long-term effects on offspring, as further understanding could lead to preventive measures to optimise offspring health, including modifiable lifestyle changes. Potential treatments for this at-risk offspring group could mitigate risk, but further studies to provide evidence are needed.

Blood pressure and hypertensive disorders of pregnancy at high altitude: a systematic review and meta-analysis

OBJECTIVE

Exposure to high altitude (≥2500 m) is associated with increased arterial blood pressure. During pregnancy, even a mild elevation of maternal blood pressure is associated with reduced birthweight and increased prevalence of pregnancy complications. This study aimed to systematically assess the impact of altitude on maternal blood pressure at term and on the prevalence of hypertensive disorders of pregnancy.

DATA SOURCES

PubMed, Ovid Embase, Cochrane Library, Medline, Web of Science, and ClinicalTrials.gov were searched (inception to November 11, 2020).

STUDY APPRAISAL AND SYNTHESIS METHODS

Observational, cohort, or case-control studies were included if they reported a high-altitude and appropriate control pregnant population. Studies published >50 years ago were excluded; 2 reviewers independently assessed articles for eligibility and risk of bias.

RESULTS

At high altitude, maternal systolic and diastolic blood pressure at term was higher than at low altitude (4.8±1.6 mm Hg; P<.001; 4.0±0.8 mm Hg; P<.001, respectively). Hypertensive disorders of pregnancy were more common at high altitude (odds ratio, 1.31 [1.03-1.65]; P<.05). The prevalence of gestational hypertension was nearly twice as high at high altitude (odds ratio, 1.92 [1.15-3.22]; P<.05) but the prevalence of preeclampsia was half as high (odds ratio, 0.57 [0.46-0.70]; P<.001). The likelihood of stillbirth was increased by 63% in pregnancies at high altitude compared with low altitude (odds ratio, 1.63 [1.12-2.35]; P<.01).

CONCLUSION

Maternal blood pressure is higher at term in pregnancies at high altitude than low altitude, accompanied with an increased risk of gestational hypertension but not preeclampsia. Risk of stillbirth at high altitude is also increased. With a growing population residing at high altitude worldwide, it is essential to clearly define the associated risk of adverse pregnancy outcomes.

Circulating Maternal sFLT1 (Soluble fms-Like Tyrosine Kinase-1) Is Sufficient to Impair Spiral Arterial Remodeling in a Preeclampsia Mouse Model

Supplemental Digital Content is available in the text.

One driving factor for developing preeclampsia—a pregnancy disorder, often associated with poor spiral artery (SpA)-remodeling and fetal growth restriction—is the anti-angiogenic sFLT1 (soluble fms-like tyrosine kinase-1), which is found to be highly upregulated in preeclampsia patients. The sFLT1-mediated endothelial dysfunction is a common theory for the manifestation of maternal preeclampsia symptoms. However, the influence of sFLT1 on SpA-remodeling and the link between placental and maternal preeclampsia symptoms is less understood. To dissect the hsFLT1 (human sFLT1) effects on maternal and/or fetoplacental physiology in preeclampsia, sFLT1-transgenic mice with systemic hsFLT1 overexpression from midgestation onwards were used. SpA-remodeling was analyzed on histological and molecular level in placental/mesometrial triangle tissues. Maternal kidney and aorta morphology was investigated, combined with blood pressure measurements via telemetry. hsFLT1 overexpression resulted in maternal hypertension, aortic wall thickening, and elastin breakdown. Furthermore, maternal kidneys showed glomerular endotheliosis, podocyte damage, and proteinuria. preeclampsia symptoms were combined with fetal growth restriction already at the end of the second trimester and SpA-remodeling was strongly impaired as shown by persisted vascular smooth muscle cells. This phenotype was associated with shallow trophoblast invasion, delayed presence of uterine natural killer cells, and altered lymphatic angiogenesis. Overall, this study showed that circulating maternal hsFLT1 is sufficient to induce typical maternal preeclampsia-like symptoms in mice and impair the SpA-remodeling independent from the fetoplacental compartment, revealing new insights into the interaction between the placental and maternal contribution of preeclampsia.

Enhanced Placental Mitochondrial Respiration in Tibetan Women at High Altitude

Living at high altitudes is extremely challenging as it entails exposure to hypoxia, low temperatures, and high levels of UV radiation. However, the Tibetan population has adapted to such conditions on both a physiological and genetic level over 30,000–40,000 years. It has long been speculated that fetal growth restriction is caused by abnormal placental development. We previously demonstrated that placentas from high-altitude Tibetans were protected from oxidative stress induced by labor compared to those of European descent. However, little is known about how placental mitochondria change during high-altitude adaptation. In this study, we aimed to uncover the mechanism of such adaptation by studying the respiratory function of the placental mitochondria of high-altitude Tibetans, lower-altitude Tibetans, and lower-altitude Chinese Han. We discovered that mitochondrial respiration was greater in high-altitude than in lower-altitude Tibetans in terms of OXPHOS via complexes I and I+II, ETS_max capacity, and non-phosphorylating respiration, whereas non-ETS respiration, LEAK/ETS, and OXPHOS via complex IV did not differ. Respiration in lower-altitude Tibetans and Han was similar for all tested respiratory states. Placentas from high-altitude Tibetan women were protected from acute ischemic/hypoxic insult induced by labor, and increased mitochondrial respiration may represent an acute response that induces mitochondrial adaptations.

Maternal Immune System and State of Inflammation Dictate the Fate and Severity of Disease in Preeclampsia

Preeclampsia, a multisystem disorder in pregnant women, is diagnosed by onset of new hypertension, proteinuria, or organ damage. Antiangiogenic factors, such as soluble fms-like tyrosine kinase 1 (sFlt1) and soluble endoglin (sEng), are long known to be involved in preeclampsia. However, the role of maternal immune system and inflammation in promotion of preeclampsia has lately been a subject of immense interest. Link between maternal inflammation and preeclampsia is not well established. Furthermore, whether cigarette smoke promotes inflammation and also promotes severity of preeclampsia remains an open question. We herein investigated correlation of established inflammation signatures in the plasma and placental tissue from cohorts of preterm preeclampsia (PPE) and preterm pregnancies (control) with or without smoking history. Besides confirming increased levels of Flt1 and Eng in preeclampsia, we also observed an increase in various mediators of maternal inflammation in women with PPE compared to preterm cohort. Increased IL-6, IL-35, and TNF-α and reduced IL-10 in serum and higher MMP-12, TLR4, HMGB-1, and iNOS and lower Foxp3, CD56 transcripts in placental tissues of PPE compared to preterm pregnancies indicate an association of preterm preeclampsia with stark imbalance in maternal immune system and signatures of inflammation. Smoker PPE cohorts showed highest inflammatory signatures including statistically significant increase for many signatures compared to other cohorts. Together, these results provide evidence for association of inflammation with PPE and strong correlation of smoking with inflammatory signatures in PPE.

Placental hypoxia: What have we learnt from small animal models?

Intrauterine hypoxia is a feature of pregnancy complications, both at high altitude and sea level. To understand the placental response to reduced oxygen availability, small animal models of maternal inhalation hypoxia (MIH) or reduced uterine perfusion pressure (RUPP) may be utilised. The aim of this review was to compare the findings of those studies to identify the role of oxygen availability in adapting placental structural and functional phenotypes in relation to fetal outcome. It also sought to explore the evidence for the involvement of particular genes and protein signalling pathways in the placenta in mediating hypoxia driven alterations. The data available demonstrate that both MIH and RUPP can induce placental hypoxia, which affects placental structure and vascularity, as well as glucose, amino acid, calcium and possibly lipid transport capacity. In addition, changes have been observed in HIF, VEGF, insulin/IGF2, AMPK, mTOR, PI3K and PPARγ signalling, which may be key in linking together observed phenotypes under conditions of placental hypoxia. Many different manipulations have been examined, with varied outcomes depending on the intensity, timing and duration of the insult. Some manipulations have detrimental effects on placental phenotype, viability and fetal growth, whereas in others, the placenta appears to adapt to uphold fetal growth despite the challenge of low oxygen. Together these data suggest a complex response of the placenta to reduced oxygen availability, which links to changes in fetal outcomes. However, further work is required to explore the role of fetal sex, altered maternal physiology and placental molecular mechanisms to fully understand placental responses to hypoxia and their relevance for pregnancy outcome.

Abnormal development of cerebral arteries and veins in offspring of experimentally preeclamptic rats: Potential role in perinatal stroke

Preeclampsia, a hypertensive disorder of pregnancy, complicates up to 10 % of all pregnancies and increases the risk for perinatal stroke in offspring. The mechanism of this increase is unknown, but may involve vascular dysfunction. The goal of this study was to evaluate the effect of experimental preeclampsia (ePE) on cerebrovascular function in offspring to eludciate a possible mechanism for this association. Dams were fed a high cholesterol diet beginning on day 7 of gestation to induce experimental preeclampsia. Middle cerebral arteries (MCA) and the Vein of Galen (VoG) were isolated from pups from ePE dams and compared to pups from normal pregnant (NP) dams at postnatal days 16, 23, and 30 and studied pressurized in an arteriograph chamber. Markers of inflammation and oxidative stress were measured in serum. Our results suggest altered structure and function in both MCA and VoG of ePE pups. We also found evidence of systemic inflammation and oxidative stress in ePE pups. These findings provide a potential link between preeclampsia and the occurrence or severity of perinatal stroke.

The Involvement of MicroRNAs in SARS-CoV-2 Infection Comorbid with HIV-Associated Preeclampsia

Purpose of Review

This review investigated the potential role of microRNAs (miRNAs) in the synergy of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection, preeclampsia (PE), and human immunodeficiency virus (HIV) infection. Maternal health is a great concern when treating pregnant women fighting this triad of diseases, which is highly prevalent in South Africa. MicroRNAs are involved in fine-tuning of physiological processes. Disruptions to the balance of this minute protein can lead to various physiological changes that are sometimes pathological.

Recent Findings

MicroRNAs have recently been implicated in PE and have been linked to the anti-angiogenic imbalance evident in PE. Recent in silico studies have identified potential host miRNAs with anti-viral properties against SARS-CoV-2 infection. Studies have demonstrated dysregulated expression of several miRNAs in HIV-1 infection along with the ability of HIV-1 to downregulate anti-viral host microRNAs.

Summary

This review has highlighted the significant gap in literature on the potential of miRNAs in women with HIV-associated PE in synergy with the novel SARS-CoV-2 infection. In addition, this review has provided evidence of the critical role that the epigenetic regulatory mechanism of miRNA plays in viral infections and PE, thereby providing a foundation for further research investigating the potential of therapeutic miRNA development with fewer side-effects for pregnant women.

Hypoxia and Mitochondrial Dysfunction in Pregnancy Complications

Hypoxia is a common and severe stress to an organism's homeostatic mechanisms, and hypoxia during gestation is associated with significantly increased incidence of maternal complications of preeclampsia, adversely impacting on the fetal development and subsequent risk for cardiovascular and metabolic disease. Human and animal studies have revealed a causative role of increased uterine vascular resistance and placental hypoxia in preeclampsia and fetal/intrauterine growth restriction (FGR/IUGR) associated with gestational hypoxia. Gestational hypoxia has a major effect on mitochondria of uteroplacental cells to overproduce reactive oxygen species (ROS), leading to oxidative stress. Excess mitochondrial ROS in turn cause uteroplacental dysfunction by damaging cellular macromolecules, which underlies the pathogenesis of preeclampsia and FGR. In this article, we review the current understanding of hypoxia-induced mitochondrial ROS and their role in placental dysfunction and the pathogenesis of pregnancy complications. In addition, therapeutic approaches selectively targeting mitochondrial ROS in the placental cells are discussed.

Distinct placental molecular processes associated with early-onset and late-onset preeclampsia

Background: Patients with preeclampsia display a spectrum of onset time and severity of clinical presentation, yet the underlying molecular bases for the early-onset and late-onset clinical subtypes are not known. Although several transcriptome studies have been done on placentae from PE patients, only a small number of differentially expressed genes have been identified due to very small sample sizes and no distinguishing of clinical subtypes. Methods: We carried out RNA-seq on 65 high-quality placenta samples, including 33 from 30 patients and 32 from 30 control subjects, to search for dysregulated genes and the molecular network and pathways they are involved in. Results: We identified two functionally distinct sets of dysregulated genes in the two major subtypes: 2,977 differentially expressed genes in early-onset severe preeclampsia, which are enriched with metabolism-related pathways, notably transporter functions; and 375 differentially expressed genes in late-onset severe preeclampsia, which are enriched with immune-related pathways. We also identified some key transcription factors, which may drive the widespread gene dysregulation in both early-onset and late-onset patients. Conclusion: These results suggest that early-onset and late-onset severe preeclampsia have different molecular mechanisms, whereas the late-onset mild preeclampsia may have no placenta-specific causal factors. A few regulators may be the key drivers of the dysregulated molecular pathways.

MiR-141-3p downregulation promotes tube formation, migration, invasion and inhibits apoptosis in hypoxia-induced human umbilical vein endothelial cells by targeting Notch2

Vascular endothelial cell damage is regarded as the carrier in the progression of the pathological changes of preeclampsia (PE) from the placenta to maternal organs. MicroRNA (miR)-141-3p was aberrantly expressed during PE pathogenesis. We investigated the role of miR-141-3p in regulating the biological behaviors of endothelial cells in PE. Human umbilical vein endothelial cells (HUVECs) were isolated from the human umbilical cords and cultured under hypoxia condition to establish PE models. The binding of miR-141-3p and Notch2 was confirmed by dual-luciferase reporter assay. HUVECs were transfected with miR-141-3p inhibitor and siRNA-Notch2. The viability, vascularization capability, migration, and invasion of HUVECs were evaluated by MTT, tube formation, and Transwell assays. Cell apoptosis was measured via flow cytometry. The expressions of miR-141-3p, Notch2, Bcl-2, Bax and cleaved caspase-3 were assessed by qRT-PCR or Western blot. MiR-141-3p expression was upregulated in the HUVECs isolated from PE tissues and hypoxia-induced HUVECs. Hypoxia treatment inhibited viability, tube formation, migration, and invasion, and promoted apoptosis in HUVECS, as well as increased Bax and cleaved caspase-3 expressions and decreased Bcl-2 expression. Downregulating miR-141-3p expression promoted viability, tube formation, migration and invasion, and inhibited apoptosis in HUVECs, counteracting the effect of hypoxia on HUVECs. MiR-141-3p directly targeted Notch2. Silencing Notch2 reversed the promoting effect of downregulated miR-141-3p expression on HUVECs. In conclusion, downregulating miR-141-3p expression during hypoxia promotes tube formation, migration, and invasion and inhibits apoptosis in HUVECs by targeting Notch2.