Abnormalities in oxygen sensing define early and late onset preeclampsia as distinct pathologies

Placental Hypoxia-Induced Ferroptosis Drives Vascular Damage in Preeclampsia

BACKGROUND

Iron is an essential micronutrient for cell survival and growth; however, excess of this metal drives ferroptosis. Although maternal iron imbalance and placental hypoxia are independent contributors to the pathogenesis of preeclampsia, a hypertensive disorder of pregnancy, the mechanisms by which their interaction impinge on maternal and placental health remain elusive.

METHODS

We used placentae from normotensive and preeclampsia pregnancy cohorts, human H9 embryonic stem cells differentiated into cytotrophoblast-like cells, and placenta-specific Phd2-/- preeclamptic mice. Lipid peroxidation and iron cargo of placenta-derived small extracellular vesicles (sEVs) isolated from the maternal circulation of control and preeclampsia individuals were examined by mass spectrometry, flow cytometry, and colorimetry. Human microvascular endothelial cells' angiogenic capacity and function were examined after exposure to control and pathological sEVs.

RESULTS

Placentae from preeclampsia pregnancies contain increased ferrous iron and lipid peroxidation byproduct, malondialdehyde. Antioxidant capacity is significantly lower in preeclampsia placentae, with decreased glutathione content, and GPx4 (glutathione peroxidase 4) expression and activity. Hypoxia triggers the occurrence of ferroptosis in human trophoblast cells and mouse Phd2-/-placentae. Disrupted placental iron homeostasis in preeclampsia is accompanied by improper extrusion of iron through sEVs mediated by the pentaspan protein prominin-2. Heightened lipid peroxidation content was found in villous explants and maternal circulating sEVs of preeclampsia individuals. Exposure of human microvascular endothelial cells to preeclampsia-derived placental sEVs results in endothelial activation and impaired angiogenesis, which is rescued by treatment with hinokitiol, a compound known to restore tissue iron balance.

CONCLUSIONS

In pregnancy, iron and oxygen work synergistically to conserve an operative antioxidant system to maintain iron homeostasis and protect the placenta from ferroptotic death. Hindrance to this system due to hypoxia results in heightened ferroptosis rates and sEV-mediated extrusion of harmful lipid peroxides from trophoblast cells into the circulation thereby contributing to maternal endothelial dysfunction characterizing preeclampsia.

sFlt-1/PlGF ratio predicts serious outcomes in confirmed early-onset preeclampsia

OBJECTIVES

We aimed to determine whether a high ratio of soluble fms-like tyrosine kinase-1 (sFlt-1) to placental growth factor (PlGF) would be associated with serious negative consequences and shorter pregnancy duration in cases of early-onset preeclampsia (PE).

STUDY DESIGN

This retrospective cohort study included women (n = 65) diagnosed with PE at <34.0 weeks of gestation and recruited from a single primary and tertiary medical centre in Japan. The sFlt-1/PlGF ratio in the study participants was measured. To determine the optimal threshold for the sFlt-1/PlGF ratio, a receiver operating characteristic curve was employed, with the aim of predicting serious adverse outcomes within 1 week after serum angiogenic marker measurements. We performed Kaplan-Meier analysis and the log-rank test to assess delivery probability based on the sFlt-1/PlGF ratio.

RESULTS

Thirty-seven women (56.9 %) delivered within 1 week of serum angiogenic marker measurements due to the aggravation of early-onset preeclampsia. Women who developed serious adverse outcomes within 1 week had a significantly higher sFlt-1/PlGF ratio than that of women who did not develop serious complications (408.5 vs. 166.6, P < 0.001). A cut-off value of 224.6 for the sFlt-1/PlGF ratio predicted serious adverse outcomes, with a sensitivity of 81.1 % and a specificity of 71.4 % (area under the curve: 0.77). Moreover, 78.9 % of women with an sFlt-1/PlGF ratio ≥ 224.6 compared to 25.9 % of those with an sFlt-1/PlGF ratio < 224.6 delivered within 1 week of presentation (P < 0.001).

CONCLUSIONS

Women with confirmed early-onset preeclampsia and high sFlt-1/PlGF ratio are more likely to develop serious adverse outcomes within 1 week after serum angiogenic marker measurements.

Streamlined Analysis of Maternal Plasma Indicates Small Extracellular Vesicles are Significantly Elevated in Early-Onset Preeclampsia

Preeclampsia (PE) is a leading cause of maternal and fetal mortality and morbidity. While placental dysfunction is a core underlying issue, the pathogenesis of this disorder is thought to differ between early-onset (EOPE) and late-onset (LOPE) subtypes. As recent reports suggest that small extracellular vesicles (sEVs) contribute to the development of PE, we have compared systemic sEV concentrations between normotensive, EOPE, and LOPE pregnancies. To circumvent lengthy isolation techniques and intermediate filtration steps, a streamlined approach was developed to evaluate circulating plasma sEVs from maternal plasma. Polymer-based precipitation and purification were used to isolate total systemic circulating maternal sEVs, free from bias toward specific surface marker expression or extensive subpurification. Immediate Nanoparticle Tracking Analysis (NTA) of freshly isolated sEV samples afforded a comprehensive analysis that can be completed within hours, avoiding confounding freeze-thaw effects of particle aggregation and degradation.Rather than exosomal subpopulations, our findings indicate a significant elevation in the total number of circulating maternal sEVs in patients with EOPE. This streamlined approach also preserves sEV-bound protein and microRNA (miRNA) that can be used for potential biomarker analysis. This study is one of the first to demonstrate that maternal plasma sEVs harbor full-length hypoxia inducible factor 1 alpha (HIF-1α) protein, with EOPE sEVs carrying higher levels of HIF-1α compared to control sEVs. The detection of HIF-1α and its direct signaling partner microRNA-210 (miR-210) within systemic maternal sEVs lays the groundwork for identifying how sEV signaling contributes to the development of preeclampsia. When taken together, our quantitative and qualitative results provide compelling evidence to support the translational potential of streamlined sEV analysis for future use in the clinical management of patients with EOPE.

Immunological mechanisms in preeclampsia: A narrative review

Maternal immunologic mechanisms for tolerance are essential for a successful pregnancy because they prevent maladaptive immune responses to the placenta and semi-allogeneic fetus and promote fetal growth. Preeclampsia is a major global cause of fetal mortality and morbidity. It is characterized by new-onset hypertension and proteinuria that occurs at twenty weeks of pregnancy or later. Preeclampsia is defined by a rise in cytokines that are pro-inflammatory and antiangiogenic components in the fetoplacental unit and the vascular endothelium of pregnant women, as well as an excessive and increasing stimulation of the immune system. Crucially, inflammation can result in low birth weight and inadequate placental perfusion in neonates. Preeclampsia, which is ultimately connected to inflammatory responses, can be impacted by several immunological mechanisms. Our goal in this work was to compile the most recent research on the pathoimmunology of preeclampsia, including studies on angiogenic variables and, in particular, immunological components.

iPSC-based modeling of preeclampsia identifies epigenetic defects in extravillous trophoblast differentiation

Preeclampsia (PE) is a hypertensive pregnancy disorder with increased risk of maternal and fetal morbidity and mortality. Abnormal extravillous trophoblast (EVT) development and function is considered to be the underlying cause of PE, but has not been previously modeled in vitro. We previously derived induced pluripotent stem cells (iPSCs) from placentas of PE patients and characterized abnormalities in formation of syncytiotrophoblast and responses to changes in oxygen tension. In this study, we converted these primed iPSC to naïve iPSC, and then derived trophoblast stem cells (TSCs) and EVT to evaluate molecular mechanisms underlying PE. We found that primed (but not naïve) iPSC-derived PE-EVT have reduced surface HLA-G, blunted invasive capacity, and altered EVT-specific gene expression. These abnormalities correlated with promoter hypermethylation of genes associated with the epithelial-mesenchymal transition pathway, specifically in primed-iPSC derived PE-EVT. Our findings indicate that abnormal epigenetic regulation might play a role in PE pathogenesis.

Progesterone receptor membrane component 2 is critical for human placental extravillous trophoblast invasion

Proper extravillous trophoblast invasion is essential for normal placentation and pregnancy. However, the molecular mechanisms by which cytotrophoblasts differentiate into extravillous trophoblast are unclear. We discovered that in the first-trimester placenta, progesterone receptor membrane component 2 was highly expressed in syncytiotrophoblast but significantly lower in extravillous trophoblast and cytotrophoblasts, indicating a divergent role for progesterone receptor membrane component 2 in trophoblast functions. We aim to examine the role of progesterone receptor membrane component 2 in extravillous trophoblasts invasion mediated by both intracellular and extracellular signals. Progesterone receptor membrane component 2 knockdown and overexpression cells were established in HTR8/SVneo cells, a first-trimester extravillous trophoblast-derived cell model, by transfection with small-interfering RNA or progesterone receptor membrane component 2 plasmids, respectively. Progesterone receptor membrane component 2 knockdown led to cellular morphological changes , enhanced trophoblast proliferation,invasion, and promoted tube formation. These effects were mediated by the activation of hypoxia-inducible factor 1alpha and an increased expression of vascular endothelial growth factor A. The culture supernatant collected from progesterone receptor membrane component 2 knockdown cells did not significantly affect extravillous trophoblast invasion compared to the controls, indicating that extracellular signaling did not robustly regulate extravillous trophoblast invasion in this study. In conclusion, attenuation of progesterone receptor membrane component 2 plays a role in placentation by promoting cell proliferation, invasion, and angiogenesis in extravillous trophoblasts via activation of hypoxia-inducible factor 1 alpha signaling. We thus identified a new function of progesterone receptor membrane component 2 and provide insights on understanding the mechanisms of trophoblast invasion.

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.

Amalgamation of Toll-Like Receptor and Hypoxic Signaling in Etiology of Preeclampsia

Inflammation and oxidative stress are involved in the pathogenesis of preeclampsia. Therefore, the aim of this study was to investigate the expression of Toll-like receptor (TLR) (TLR-4, HMGB1, NFκB, IκBα) and hypoxic (HIF-1α, HIF-1β, PHD, pVHL) pathway proteins in the placenta of preeclamptic pregnant women after 28 weeks of gestational period. A possible association between these 2 pathways was also explored. A total of 194 placental tissues of preeclamptic as well as healthy pregnant women were analyzed by immunohistochemistry. On the basis of gestational age, the samples were divided into 2 groups, I (28-36 wk) and II (36 wk onwards), with 55 and 139 samples in the respective groups. The expression of both TLR (TLR-4, HMGB1, NFκB, IκBα) and hypoxic (HIF-1α, HIF-1β, PHD, pVHL) pathway proteins were significantly modulated in the placental tissues of preeclampsia as compared with control. The 2 pathways were interlinked in preeclampsia. This study highlights the intercorrelation of both TLR and hypoxic signalling pathways that may be a causative factor for the pathophysiology of preeclampsia.

Expression of placental glycans and its role in regulating peripheral blood NK cells during preeclampsia: a perspective

Preeclampsia is a pregnancy-related multisystem disorder characterized by altered trophoblast invasion, oxidative stress, exacerbation of systemic inflammatory response, and endothelial damage. The pathogenesis includes hypertension and mild-to-severe microangiopathy in the kidney, liver, placenta, and brain. The main mechanisms involved in its pathogenesis have been proposed to limit trophoblast invasion and increase the release of extracellular vesicles from the syncytiotrophoblast into the maternal circulation, exacerbating the systemic inflammatory response. The placenta expresses glycans as part of its development and maternal immune tolerance during gestation. The expression profile of glycans at the maternal-fetal interface may play a fundamental role in physiological pregnancy changes and disorders such as preeclampsia. It is unclear whether glycans and their lectin-like receptors are involved in the mechanisms of maternal-fetal recognition by immune cells during pregnancy homeostasis. The expression profile of glycans appears to be altered in hypertensive disorders of pregnancy, which could lead to alterations in the placental microenvironment and vascular endothelium in pregnancy conditions such as preeclampsia. Glycans with immunomodulatory properties at the maternal-fetal interface are altered in early-onset severe preeclampsia, implying that innate immune system components, such as NK cells, exacerbate the systemic inflammatory response observed in preeclampsia. In this article, we discuss the evidence for the role of glycans in gestational physiology and the perspective of glycobiology on the pathophysiology of hypertensive disorders in gestation.

Fibronectin and JMJD6 Signature in Circulating Placental Extracellular Vesicles for the Detection of Preeclampsia

Preeclampsia (PE) is a major obstetric complication that is challenging to predict. Currently, there are limited tools to assess placental health/function in crucial gestational periods for diagnosis and early prediction. The glycoprotein fibronectin (FN) is augmented in PE placentae, and associated with reduced activity of JMJD6, an oxygen sensor that regulates placental FN processing. Evidence implicates placenta-derived small extracellular vesicles (sEVs) in the pathogenesis of pregnancy-associated disorders. Here, we examined the utility of FN and JMJD6 in placental sEVs as putative markers for early- and late-onset PE (E-PE and L-PE). Maternal plasma was obtained from venous blood collected longitudinally during pregnancy (10-14, 16-22, and 26-32 weeks of gestation and at delivery) in normotensive term control, preterm control, L-PE, E-PE, and gestational hypertensive individuals. Placenta-derived sEVs were isolated and their FN and JMJD6 content and JMJD6 activity were measured. In women that went on to develop preeclampsia, FN content of circulating placental sEVs was significantly elevated as early as 10 to 14 weeks of gestation and remained augmented until the time of delivery. This was accompanied by a depletion in JMJD6 content. Multivariate receiver operating characteristic analysis revealed high predictive power for FN and JMJD6 as early markers of E-PE and L-PE. In vitro, hypoxia or JMJD6 loss promoted FN accumulation in sEVs that was reverted on restoring cellular iron balance with the natural compound, Hinokitiol. Elevated FN, along with diminished JMJD6 in circulating placental sEVs, serves as an early molecular signature for the detection of different hypertensive disorders of pregnancy and their severity.

Ca2+-Activated K+ Channels and the Regulation of the Uteroplacental Circulation

Adequate uteroplacental blood supply is essential for the development and growth of the placenta and fetus during pregnancy. Aberrant uteroplacental perfusion is associated with pregnancy complications such as preeclampsia, fetal growth restriction (FGR), and gestational diabetes. The regulation of uteroplacental blood flow is thus vital to the well-being of the mother and fetus. Ca²⁺-activated K⁺ (K_Ca) channels of small, intermediate, and large conductance participate in setting and regulating the resting membrane potential of vascular smooth muscle cells (VSMCs) and endothelial cells (ECs) and play a critical role in controlling vascular tone and blood pressure. K_Ca channels are important mediators of estrogen/pregnancy-induced adaptive changes in the uteroplacental circulation. Activation of the channels hyperpolarizes uteroplacental VSMCs/ECs, leading to attenuated vascular tone, blunted vasopressor responses, and increased uteroplacental blood flow. However, the regulation of uteroplacental vascular function by K_Ca channels is compromised in pregnancy complications. This review intends to provide a comprehensive overview of roles of K_Ca channels in the regulation of the uteroplacental circulation under physiological and pathophysiological conditions.

HIF1 inhibitor acriflavine rescues early-onset preeclampsia phenotype in mice lacking placental prolyl hydroxylase domain protein 2

Preeclampsia is a serious pregnancy disorder that lacks effective treatments other than delivery. Improper sensing of oxygen changes during placentation by prolyl hydroxylases (PHDs), specifically PHD2, causes placental hypoxia-inducible factor-1 (HIF1) buildup and abnormal downstream signaling in early-onset preeclampsia, yet therapeutic targeting of HIF1 has never been attempted. Here we generated a conditional (placenta-specific) knockout of Phd2 in mice (Phd2-/- cKO) to reproduce HIF1 excess and to assess anti-HIF therapy. Conditional deletion of Phd2 in the junctional zone during pregnancy increased placental HIF1 content, resulting in abnormal placentation, impaired remodeling of the uterine spiral arteries, and fetal growth restriction. Pregnant dams developed new-onset hypertension at midgestation (E9.5) in addition to proteinuria and renal and cardiac pathology, hallmarks of severe preeclampsia in humans. Daily injection of acriflavine, a small molecule inhibitor of HIF1, to pregnant Phd2-/- cKO mice from E7.5 (prior to hypertension) or E10.5 (after hypertension had been established) to E14.5 corrected placental dysmorphologies and improved fetal growth. Moreover, it reduced maternal blood pressure and reverted renal and myocardial pathology. Thus, therapeutic targeting of the HIF pathway may improve placental development and function, as well as maternal and fetal health, in preeclampsia.

Hypoxia-Inducible Factor 1 and Preeclampsia: A New Perspective

PURPOSE OF REVIEW

Preeclampsia (PE) is a serious and distinct type of pregnancy-induced hypertension, with an incidence of 2-8% worldwide. PE is defined as pregnancy-related hypertension with proteinuria and peripheral edema after 20 weeks of gestation. Hypoxic placenta triggers the release of inflammatory and humoral substances into maternal circulation, leading to induction of oxidative stress, lipid peroxidation, endothelial dysfunction, and peripheral vasoconstriction. The objective of the present narrative review was to find the association between PE and hypoxia-inducible factor 1 (HIF-1) in pregnant women from a new perspective.

RECENT FINDINGS

HIF-1 is the key transcription factor that regulates cellular responses to hypoxia and low oxygen tension. HIF-1α is involved in the differentiation and growth of the placenta mainly in the first and second trimesters. During normal gestation, HIF-1α responds to the alterations in oxygen tension, cytokine, and angiogenic factors release. HIF-1α is considered a key biomarker of placental function and vascularization during pregnancy. HIF-1α plays a crucial role in the pathogenesis of PE through activation of anti-angiogenic and inhibition of proangiogenic factors. As well, HIF-1α increases the expression of the p38MAPK and NLRP3 inflammasomes, which promote placental inflammation and dysfunction. HIF-1α acts as a potential link between inflammatory signaling pathways and the development of PE.

The Asparagine Hydroxylase FIH: A Unique Oxygen Sensor

Significance: Limited oxygen availability (hypoxia) commonly occurs in a range of physiological and pathophysiological conditions, including embryonic development, physical exercise, inflammation, and ischemia. It is thus vital for cells and tissues to monitor their local oxygen availability to be able to adjust in case the oxygen supply is decreased. The cellular oxygen sensor factor inhibiting hypoxia-inducible factor (FIH) is the only known asparagine hydroxylase with hypoxia sensitivity. FIH uniquely combines oxygen and peroxide sensitivity, serving as an oxygen and oxidant sensor. Recent Advances: FIH was first discovered in the hypoxia-inducible factor (HIF) pathway as a modulator of HIF transactivation activity. Several other FIH substrates have now been identified outside the HIF pathway. Moreover, FIH enzymatic activity is highly promiscuous and not limited to asparagine hydroxylation. This includes the FIH-mediated catalysis of an oxygen-dependent stable (likely covalent) bond formation between FIH and selected substrate proteins (called oxomers [oxygen-dependent stable protein oligomers]). Critical Issues: The (patho-)physiological function of FIH is only beginning to be understood and appears to be complex. Selective pharmacologic inhibition of FIH over other oxygen sensors is possible, opening new avenues for therapeutic targeting of hypoxia-associated diseases, increasing the interest in its (patho-)physiological relevance. Future Directions: The contribution of FIH enzymatic activity to disease development and progression should be analyzed in more detail, including the assessment of underlying molecular mechanisms and relevant FIH substrate proteins. Also, the molecular mechanism(s) involved in the physiological functions of FIH remain(s) to be determined. Furthermore, the therapeutic potential of recently developed FIH-selective pharmacologic inhibitors will need detailed assessment. Antioxid. Redox Signal. 37, 913-935.

Hypoxia-Reoxygenation Impairs Autophagy-Lysosomal Machinery in Primary Human Trophoblasts Mimicking Placental Pathology of Early-Onset Preeclampsia

We have previously described that placental activation of autophagy is a central feature of normal pregnancy, whereas autophagy is impaired in preeclampsia (PE). Here, we show that hypoxia-reoxygenation (H/R) treatment dysregulates key molecules that maintain autophagy-lysosomal flux in primary human trophoblasts (PHTs). Ultrastructural analysis using transmission electron microscopy reveals a significant reduction in autophagosomes and autolysosomes in H/R-exposed PHTs. H/R-induced accumulation of protein aggregates follows a similar pattern that occurs in PHTs treated with a lysosomal disruptor, chloroquine. Importantly, the placenta from early-onset PE deliveries exhibits the same features as seen in H/R-treated PHTs. Taken together, our results indicate that H/R disrupts autophagic machinery in PHTs and that impaired autophagy in the placenta from early-onset PE deliveries mimics the events in H/R-treated PHTs. Notably, assessment of key regulators at each stage of autophagic processes, especially lysosomal integrity, and verification of autophagic ultrastructure are essential for an accurate evaluation of autophagy activity in human trophoblasts and placental tissue from PE deliveries.

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

Preeclampsia (PE) and intrauterine growth restriction (IUGR) are the leading causes of maternal and fetal morbidity/mortality. The central deficit in both conditions is impaired placentation due to poor trophoblast invasion, resulting in a hypoxic milieu in which oxidative stress contributes to the pathology. We examine the factors driving the hypoxic response in severely preterm PE (n = 19) and IUGR (n = 16) placentae compared to the spontaneous preterm (SPT) controls (n = 13) using immunoblotting, RT-PCR, immunohistochemistry, proximity ligation assays, and Co-IP. Both hypoxia-inducible factor (HIF)-1α and HIF-2α are increased at the protein level and functional in pathological placentae, as target genes prolyl hydroxylase domain (PHD)2, PHD3, and soluble fms-like tyrosine kinase-1 (sFlt-1) are increased. Accumulation of HIF-α-subunits occurs in the presence of accessory molecules required for their degradation (PHD1, PHD2, and PHD3 and the E3 ligase von Hippel–Lindau (VHL)), which were equally expressed or elevated in the placental lysates of PE and IUGR. However, complex formation between VHL and HIF-α-subunits is defective. This is associated with enhanced VHL/DJ1 complex formation in both PE and IUGR. In conclusion, we establish a significant mechanism driving the maladaptive responses to hypoxia in the placentae from severe PE and IUGR, which is central to the pathogenesis of both diseases.

Dichotomy in hypoxia-induced mitochondrial fission in placental mesenchymal cells during development and preeclampsia: consequences for trophoblast mitochondrial homeostasis

Dynamic changes in physiologic oxygen are required for proper placenta development; yet, when low-oxygen levels persist, placental development is halted, culminating in preeclampsia (PE), a serious complication of pregnancy. Considering mitochondria’s function is intimately linked to oxygen changes, we investigated the impact of oxygen on mitochondrial dynamics in placental mesenchymal stromal cells (pMSCs) that are vital for proper placental development. Transmission electron microscopy, proximity ligation assays for mitochondrial VDAC1 and endoplasmic reticulum IP3R, and immunoanalyses of p-DRP1 and OPA1, demonstrate that low-oxygen conditions in early 1st trimester and PE promote mitochondrial fission in pMSCs. Increased mitochondrial fission of mesenchymal cells was confirmed in whole PE placental tissue sections. Inhibition of DRP1 oligomerization with MDiVi-1 shows that low oxygen-induced mitochondrial fission is a direct consequence of DRP1 activation, likely via HIF1. Mitophagy, a downstream event prompted by mitochondrial fission, is a prominent outcome in PE, but not 1st trimester pMSCs. We also investigated whether mesenchymal–epithelial interactions affect mitochondrial dynamics of trophoblasts in PE placentae. Exposure of trophoblastic JEG3 cells to exosomes of preeclamptic pMSCs caused heightened mitochondrial fission in the cells via a sphingomyelin-dependent mechanism that was restored by MDiVi-1. Our data uncovered dichotomous regulation of mitochondrial fission and health in human placental mesenchymal cells under physiologic and pathologic hypoxic conditions and its impact on neighboring trophoblast cells.

Could Vitamin D Be Effective in Prevention of Preeclampsia?

Prevention of preeclampsia (PE) remains one of the most significant problems in perinatal medicine. Due to the possible unpredictable course of hypertension in pregnancy, primarily PE and the high complication rate for the mother and fetus/newborn, it is urgent to offer pregnant women in high-risk groups effective methods of preventing the PE development or delaying its appearance. In addition, due to the association of PE with an increased risk of developing cardiovascular diseases (CVD) in later life, effective preeclampsia prevention could also be important in reducing their incidence. Ideal PE prophylaxis should target the pathogenetic changes leading to the development of PE and be safe for the mother and fetus, inexpensive and freely available. Currently, the only recognized method of PE prevention recommended by many institutions around the world is the use of a small dose of acetylsalicylic acid in pregnant women with risk factors. Unfortunately, some cases of PE are diagnosed in women without recognized risk factors and in those in whom prophylaxis with acetylsalicylic acid is not adequate. Hence, new drugs which would target pathogenetic elements in the development of preeclampsia are studied. Vitamin D (Vit D) seems to be a promising agent due to its beneficial effect on placental implantation, the immune system, and angiogenic factors. Studies published so far emphasize the relationship of its deficiency with the development of PE, but the data on the benefits of its supplementation to reduce the risk of PE are inconclusive. In the light of current research, the key issue is determining the protective concentration of Vit D in a pregnant woman. The study aims to present the possibility of using Vit D to prevent PE, emphasizing its impact on the pathogenetic elements of preeclampsia development.

Hypoxia and the integrated stress response promote pulmonary hypertension and preeclampsia: Implications in drug development

Chronic hypoxia is a common cause of pulmonary hypertension, preeclampsia, and intrauterine growth restriction (IUGR). The molecular mechanisms underlying these diseases are not completely understood. Chronic hypoxia may induce the generation of reactive oxygen species (ROS) in mitochondria, promote endoplasmic reticulum (ER) stress, and result in the integrated stress response (ISR) in the pulmonary artery and uteroplacental tissues. Numerous studies have implicated hypoxia-inducible factors (HIFs), oxidative stress, and ER stress/unfolded protein response (UPR) in the development of pulmonary hypertension, preeclampsia and IUGR. This review highlights the roles of HIFs, mitochondria-derived ROS and UPR, as well as their interplay, in the pathogenesis of pulmonary hypertension and preeclampsia, and their implications in drug development.

Current State of Preeclampsia Mouse Models: Approaches, Relevance, and Standardization

Preeclampsia (PE) is a multisystemic, pregnancy-specific disorder and a leading cause of maternal and fetal death. PE is also associated with an increased risk for chronic morbidities later in life for mother and offspring. Abnormal placentation or placental function has been well-established as central to the genesis of PE; yet much remains to be determined about the factors involved in the development of this condition. Despite decades of investigation and many clinical trials, the only definitive treatment is parturition. To better understand the condition and identify potential targets preclinically, many approaches to simulate PE in mice have been developed and include mixed mouse strain crosses, genetic overexpression and knockout, exogenous agent administration, surgical manipulation, systemic adenoviral infection, and trophoblast-specific gene transfer. These models have been useful to investigate how biological perturbations identified in human PE are involved in the generation of PE-like symptoms and have improved the understanding of the molecular mechanisms underpinning the human condition. However, these approaches were characterized by a wide variety of physiological endpoints, which can make it difficult to compare effects across models and many of these approaches have aspects that lack physiological relevance to this human disorder and may interfere with therapeutic development. This report provides a comprehensive review of mouse models that exhibit PE-like symptoms and a proposed standardization of physiological characteristics for analysis in murine models of PE.

Human placental gene sets improve analysis of placental pathologies and link trophoblast and cancer invasion genes

INTRODUCTION

Interpretation of gene expression uses set enrichment or overrepresentation methods that depend on sets of annotated genes, such as the popular Gene Ontology. The placenta is understudied relative to other major organs creating a deficit of molecular and functional knowledge about this organ. The lack of placental and trophoblast research significantly impacts our ability to interpret the results of high throughput experiments.

METHODS

Gene sets were generated by a semi-automated re-analysis of 330 microarray and 91 RNA sequencing experiments involving placental and trophoblast samples, excluding those related to pathology. Microarray data was obtained from the Gene Expression Omnibus and processed using the R package limma. RNA-sequencing data was extracted from the short read archive and processed using Kallisto and limma. The workflow consisted of quality control for experimental design and data. Sets were generated by pairwise differential expression with a maximum of 200 genes per set.

RESULTS

We created 235 human placenta and trophoblast specific gene sets and found unique subnetworks relative to Gene Ontology. We applied these new placental gene sets to the investigation of preeclampsia and fetal growth restriction as well as invasive tumors and cell models finding matching terms related to cell types and oxygen tension (hypoxia).

DISCUSSION

The human placental gene sets provide an improved context for interpretation of high throughput gene expression studies on placental pathologies beyond the Gene Ontology. Significant enrichment of placental gene sets to cancer samples and cell models indicates a utility beyond applications to placental and trophoblast cells.

The Role of Leptin in Fetal Growth during Pre-Eclampsia

Leptin is secreted by the placenta and has a multi-facetted role in the regulation of functions related to pregnancy. Metabolic disorders and insufficient homeostatic compensatory mechanisms involving leptin during pregnancy play a decisive role in the development of pre-eclampsia (PE) and give rise to compromised intrauterine growth conditions and aberrant birth weight of offspring. This review was compiled to elucidate the metabolic background of PE and its relationship with adverse intrauterine growth conditions through the examination of leptin as well as to describe possible mechanisms linking leptin to fetal growth restriction. This review illustrates that leptin in PE is dysregulated in maternal, fetal, and placental compartments. There is no single set of unifying mechanisms within the spectrum of PE, and regulatory mechanisms involving leptin are specific to each situation. We conclude that dysregulated leptin is involved in fetal growth at many levels through complex interactions with parallel pregnancy systems and probably throughout the entirety of pregnancy.

Prognostic role of increased serum homocysteine concentration in preeclampsia

Objective: To assess homocysteine (Hcy) concentration in women with preeclampsia (PE).Methods: Hcy concentrations were detected by ELISA in 305 pregnancies.Results: Hcy concentration in patients with PE was 16.07 umol/L at 10-14 weeks as compared to 7.19 umol/L in normotensive pregnancies (p < 0.0001). Optimal cutoff level for Hcy in the first trimester of pregnancy was >9.55 umol/L with area under curve of 0.859, sensitivity of 91.67%, specificity of 72.24%.Conclusion: Assessment of serum Hcy concentration may be used as a predictor of PE, with the highest diagnostic utility in the first trimester of pregnancy.

Increased pulsatility index of uterine artery Doppler between 26 and 28 weeks of gestation and adverse perinatal outcomes

OBJECTIVE

To compare adverse perinatal outcomes in pregnant women with or without normalization of the mean pulsatility index (PI) uterine artery Doppler between 24 and 28 weeks of gestation.

METHODS

Retrospective cohort which pregnant women were divided into three groups: normal uterine artery Doppler between 20-24 and 26-28 weeks (controls), abnormal uterine artery Doppler between 20-24 and normal between 26-28 weeks (anUtA), and abnormal uterine artery Doppler between 20-24 and 26-28 weeks (aaUtA). To compare adverse perinatal results between the groups Chi-square test was used. Binary logistic regression was used to assess the ability of uterine artery Doppler to predict birthweight < 10th and composite perinatal outcomes.

RESULTS

Birthweight was significantly lower in the aaUtA compared to anUtA (2687 vs 3248 grams, p = 0.0479). A significant negative correlation was observed between the mean PI uterine artery Doppler during the 3rd trimester and birthweight (r = -0.13, R ² = 0.035, p = .0192). The prevalence of composite perinatal outcomes was significantly higher in aaUtA compared to anUtA (25.9 vs 0%, p = .013). Mean PI uterine artery Doppler during the 3rd trimester was significant predictor for birthweight < 10th (OR: 2.74, CI 95% = 1.03-7.3), but the protodiastolic notch and the association between mean PI uterine artery Doppler and protodiastolic notch were not.

CONCLUSION

Maintenance of altered uterine artery Doppler during the 3rd trimester was associated with higher prevalence of composite perinatal outcomes and lower birthweight compared to its late normalization. Although modest, uterine artery Doppler in the 3rd trimester proved to be predictor of birthweight < 10th.

The Critical Roles of the SUMO-Specific Protease SENP3 in Human Diseases and Clinical Implications

Post-translational modification by SUMO (small ubiquitin-like modifier) proteins has been shown to regulate a variety of functions of proteins, including protein stability, chromatin organization, transcription, DNA repair, subcellular localization, protein–protein interactions, and protein homeostasis. SENP (sentrin/SUMO-specific protease) regulates precursor processing and deconjugation of SUMO to control cellular mechanisms. SENP3, which is one of the SENP family members, deconjugates target proteins to alter protein modification. The effect of modification via SUMO and SENP3 is crucial to maintain the balance of SUMOylation and guarantee normal protein function and cellular activities. SENP3 acts as an oxidative stress-responsive molecule under physiological conditions. Under pathological conditions, if the SUMOylation process of proteins is affected by variations in SENP3 levels, it will cause a cellular reaction and ultimately lead to abnormal cellular activities and the occurrence and development of human diseases, including cardiovascular diseases, neurological diseases, and various cancers. In this review, we summarized the most recent advances concerning the critical roles of SENP3 in normal physiological and pathological conditions as well as the potential clinical implications in various diseases. Targeting SENP3 alone or in combination with current therapies might provide powerful targeted therapeutic strategies for the treatment of these diseases.

Nanoparticle-Mediated Simultaneous Downregulation of Placental Nrf2 and sFlt1 Improves Maternal and Fetal Outcomes in a Preeclampsia Mouse Model

Preeclampsia has impacted 3-5% pregnancies among the world and its complications lead to both maternal and fetal morbidity and mortality. However, management of preeclampsia is limited. Nanoparticles targeting chondroitin sulfate A (CSA) can deliver drugs to placenta. Inactivation of soluble fms-like tyrosine kinase (sFlt-1) and nuclear factor-erythroid 2-like 2 (Nrf2) has been proved to alleviate preeclampsia and improve maternal and fetal outcomes. Carboxyl-polyethylene glycol-poly (d,l-lactide) (COOH-PEG5K-PLA8K), cationic lipid DOTAP, and siNrf2 and sisFlt-1 were used to construct the nanoparticles and conjugating peptides targeting CSA was fabricated to it. The expression levels of proteins and RNAs were estimated by qRT-PCR and Western blot assays. ELISA assays were performed to evaluate levels of circulating sFlt-1. The nanoparticles containing siNrf2 and sisFlt-1 are targeted to the placenta trophoblasts and downregulated the expression levels of Nrf2 and sFlt-1 as well as their downstream genes in the placental cells of model mice. Treatment of nanoparticles induced the expression of angiogenic factors in placenta. Knocking down Nrf2 and sFlt-1 synchronously alleviated the preeclampsia and increased the maternal and fetal outcomes in preeclampsia model mice. Nanoparticle-mediated simultaneous downregulation of placental Nrf2 and sFlt1 improved maternal and fetal outcomes in a preeclampsia mouse model.

Tracking placental development in health and disease

Pre-eclampsia and fetal growth restriction arise from disorders of placental development and have some shared mechanistic features. Initiation is often rooted in the maldevelopment of a maternal-placental blood supply capable of providing for the growth requirements of the fetus in later pregnancy, without exerting undue stress on maternal body systems. Here, we review normal development of a placental bed with a safe and adequate blood supply and a villous placenta-blood interface from which nutrients and oxygen can be extracted for the growing fetus. We consider disease mechanisms that are intrinsic to the maternal environment, the placenta or the interaction between the two. Systemic signalling from the endocrine placenta targets the maternal endothelium and multiple organs to adjust metabolism for an optimal pregnancy and later lactation. This signalling capacity is skewed when placental damage occurs and can deliver a dangerous pathogenic stimulus. We discuss the placental secretome including glycoproteins, microRNAs and extracellular vesicles as potential biomarkers of disease. Angiomodulatory mediators, currently the only effective biomarkers, are discussed alongside non-invasive imaging approaches to the prediction of disease risk. Identifying the signs of impending pathology early enough to intervene and ameliorate disease in later pregnancy remains a complex and challenging objective.

Hypoxia-induced Downregulation of SRC-3 Suppresses Trophoblastic Invasion and Migration Through Inhibition of the AKT/mTOR Pathway: Implications for the Pathogenesis of Preeclampsia

Preeclampsia (PE) is characterized by poor placentation, consequent on aberrant extravillous trophoblast (EVT) cell function during placental development. The SRC family of proteins is important during pregnancy, especially SRC-3, which regulates placental morphogenesis and embryo survival. Although SRC-3 expression in mouse trophoblast giant cells has been documented, its role in the functional regulation of extravillous trophoblasts and the development of PE remains unknown. This study found that SRC-3 expression was significantly lower in placentas from PE pregnancies as compared to uncomplicated pregnancies. Additionally, both CoCl₂-mimicked hypoxia and suppression of endogenous SRC-3 expression by lentivirus short hairpin RNA attenuated the migration and invasion abilities of HTR-8/SVneo cells. Moreover, we demonstrated that SRC-3 physically interacts with AKT to regulate the migration and invasion of HTR-8 cells, via the AKT/mTOR pathway. We also found that the inhibition of HTR-8 cell migration and invasion by CoCl₂-mimicked hypoxia was through the SRC-3/AKT/mTOR axis. Our findings indicate that, in early gestation, accumulation of HIF-1α inhibits the expression of SRC-3, which impairs extravillous trophoblastic invasion and migration by directly interacting with AKT. This potentially leads to insufficient uterine spiral artery remodeling and placental hypoperfusion, and thus the development of PE.

The Difference in Maternal Serum Hypoxia-Inducible Factors-1α Levels between Early Onset and Late-Onset Preeclampsia

BACKGROUND

Preeclampsia can be divided into early (EOPE) and late (LOPE) onset preeclampsia. Preeclampsia is related to the failure of placentation. Accumulation of hypoxia-inducible factors (HIF)-1α is commonly an acute and beneficial respond to hypoxia, while chronically elevated is associated with preeclampsia.

AIM

This study aims to evaluate the serum levels of HIF-1α in preeclampsia and normal pregnancy, and to compare the difference between early-onset and late-onset preeclampsia.

METHODS

A cross-sectional comparative study was conducted among a total of 69 pregnant women at ≥ 20 weeks of gestation, were recruited at obstetrics and gynaecology department at Dr M. Djamil Padang Hospital, network hospitals, health centres. They were divided into three groups early-onset preeclampsia, late-onset preeclampsia, and normal pregnancy. Preeclampsia was diagnosed using International Guidelines. Data were analysed by SPSS 24 program; data are presented as median and range or as mean ± standard deviation. One-way ANOVA test was used to determine the relationship between HIF-1α levels with the onset of preeclampsia.

RESULTS

The results showed that the mean maternal serum HIF-1α levels in early-onset preeclampsia (EOPE), late-onset preeclampsia (LOPE), and normal pregnancy were 1366.96 ± 733.40 pg/ml, 916.87 ± 466.06 pg/ml, and 716.77 ± 541.08 pg/ml. Serum HIF-1α levels were higher in early-onset preeclampsia (EOPE), and late-onset preeclampsia (LOPE) compared to normal pregnancy. Among preeclampsia patients, serum HIF-1α was higher in EOPE than LOPE women. Statistical analysis revealed a significant difference in mean maternal serum HIF-1α between early-onset preeclampsia, late-onset preeclampsia, and normal pregnancy (p < 0.05).

CONCLUSION

This study concluded that there is a significantly different level of HIF-1α between in early-onset preeclampsia, late-onset preeclampsia and normal pregnancy. Early-onset preeclampsia is the highest levels of serum HIF-1α.

Early-life determinants of hypoxia-inducible factor 3A gene (HIF3A) methylation: a birth cohort study

Background

Methylation of the hypoxia-inducible factor 3α gene (HIF3A) has been linked to pregnancy exposures, infant adiposity and later BMI. Genetic variation influences HIF3A methylation levels and may modify these relationships. However, data in very early life are limited, particularly in association with adverse pregnancy outcomes. We investigated the relationship between maternal and gestational factors, infant anthropometry, genetic variation and HIF3A DNA methylation in the Barwon Infant Study, a population-based birth cohort. Methylation of two previously studied regions of HIF3A were tested in the cord blood mononuclear cells of 938 infants.

Results

No compelling evidence was found of an association between birth weight, adiposity or maternal gestational diabetes with methylation at the most widely studied HIF3A region. Male sex (− 4.3%, p < 0.001) and pre-eclampsia (− 5.4%, p = 0.02) negatively associated with methylation at a second region of HIF3A; while positive associations were identified for gestational diabetes (4.8%, p = 0.01) and gestational age (1.2% increase per week, p < 0.001). HIF3A genetic variation also associated strongly with methylation at this region (p < 0.001).

Conclusions

Pre- and perinatal factors impact HIF3A methylation, including pre-eclampsia. This provides evidence that specific pregnancy complications, previously linked to adverse outcomes for both mother and child, impact the infant epigenome in a molecular pathway critical to several vascular and metabolic conditions. Further work is required to understand the mechanisms and clinical relevance, particularly the differing effects of in utero exposure to gestational diabetes or pre-eclampsia.

Electronic supplementary material

The online version of this article (10.1186/s13148-019-0687-0) contains supplementary material, which is available to authorized users.

Faulty oxygen sensing disrupts angiomotin function in trophoblast cell migration and predisposes to preeclampsia

Human placenta development and a successful pregnancy is incumbent upon precise oxygen-dependent control of trophoblast migration/invasion. Persistent low oxygen leading to failed trophoblast invasion promotes inadequate spiral artery remodeling, a characteristic of preeclampsia. Angiomotin (AMOT) is a multifaceted scaffolding protein involved in cell polarity and migration, yet its upstream regulation and significance in the human placenta remain unknown. Herein, we show that AMOT is primarily expressed in migratory extravillous trophoblast cells (EVTs) of the intermediate and distal anchoring column. Its expression increases after 10 weeks of gestation when oxygen tension rises and EVT migration/invasion peaks. Time-lapse imaging confirmed that the AMOT 80-kDa isoform promotes migration of trophoblastic JEG3 and HTR-8/SVneo cells. In preeclampsia, however, AMOT expression is decreased and its localization to migratory fetomaternal interface EVTs is disrupted. We demonstrate that Jumonji C domain-containing protein 6 (JMJD6), an oxygen sensor, positively regulates AMOT via oxygen-dependent lysyl hydroxylation. Furthermore, in vitro and ex vivo studies show that transforming growth factor-β (TGF-β) regulates AMOT expression, its interaction with polarity protein PAR6, and its subcellular redistribution from tight junctions to cytoskeleton. Our data reveal an oxygen- and TGF-β-driven migratory function for AMOT in the human placenta, and implicate its deficiency in impaired trophoblast migration that plagues preeclampsia.

Trophoblast-Specific Expression of Hif-1α Results in Preeclampsia-Like Symptoms and Fetal Growth Restriction

The placenta is an essential organ that is formed during pregnancy and its proper development is critical for embryonic survival. While several animal models have been shown to exhibit some of the pathological effects present in human preeclampsia, these models often do not represent the physiological aspects that have been identified. Hypoxia-inducible factor 1 alpha (Hif-1α) is a necessary component of the cellular oxygen-sensing machinery and has been implicated as a major regulator of trophoblast differentiation. Elevated levels of Hif-1α in the human placenta have been linked to the development of pregnancy-associated disorders, such as preeclampsia and fetal growth restriction. As oxygen regulation is a critical determinant for placentogenesis, we determined the effects of constitutively active Hif-1α, specifically in trophoblasts, on mouse placental development in vivo. Our research indicates that prolonged expression of trophoblast-specific Hif-1α leads to a significant decrease in fetal birth weight. In addition, we noted significant physiological alterations in placental differentiation that included reduced branching morphogenesis, alterations in maternal and fetal blood spaces, and failure to remodel the maternal spiral arteries. These placental alterations resulted in subsequent maternal hypertension with parturitional resolution and maternal kidney glomeruloendotheliosis with accompanying proteinuria, classic hallmarks of preeclampsia. Our findings identify Hif-1α as a critical molecular mediator of placental development and indicate that prolonged expression of Hif-1α, explicitly in placental trophoblasts causes maternal pathology and establishes a mouse model that significantly recapitulates the physiological and pathophysiological characteristics of preeclampsia with fetal growth restriction.

Early onset preeclampsia in a model for human placental trophoblast

Preeclampsia, a leading cause of maternal and perinatal morbidity and mortality worldwide, is accompanied by shallow placentation and deficient remodeling of the uterine spiral arteries by invasive placental trophoblast cells during the first trimester of pregnancy. Here, we generated induced pluripotent stem cells from umbilical cords of normal pregnancies and ones complicated by early onset preeclampsia (EOPE) and converted them to trophoblast to recapitulate events of early pregnancy. Parameters disturbed in EOPE, including trophoblast invasiveness, were assessed. Under low O₂, both sets of cells behaved similarly, but, under the more stressful 20% O₂ conditions, the invasiveness of EOPE trophoblast was markedly reduced. Gene expression changes in EOPE trophoblast suggested a dysregulation invasion linked to high O₂.

We describe a model for early onset preeclampsia (EOPE) that uses induced pluripotent stem cells (iPSCs) generated from umbilical cords of EOPE and control (CTL) pregnancies. These iPSCs were then converted to placental trophoblast (TB) representative of early pregnancy. Marker gene analysis indicated that both sets of cells differentiated at comparable rates. The cells were tested for parameters disturbed in EOPE, including invasive potential. Under 5% O₂, CTL TB and EOPE TB lines did not differ, but, under hyperoxia (20% O₂), invasiveness of EOPE TB was reduced. RNA sequencing analysis disclosed no consistent differences in expression of individual genes between EOPE TB and CTL TB under 20% O₂, but, a weighted correlation network analysis revealed two gene modules (CTL4 and CTL9) that, in CTL TB, were significantly linked to extent of TB invasion. CTL9, which was positively correlated with 20% O₂ (P = 0.02) and negatively correlated with invasion (P = 0.03), was enriched for gene ontology terms relating to cell adhesion and migration, angiogenesis, preeclampsia, and stress. Two EOPE TB modules, EOPE1 and EOPE2, also correlated positively and negatively, respectively, with 20% O₂ conditions, but only weakly with invasion; they largely contained the same sets of genes present in modules CTL4 and CTL9. Our experiments suggest that, in EOPE, the initial step precipitating disease is a reduced capacity of placental TB to invade caused by a dysregulation of O₂ response mechanisms and that EOPE is a syndrome, in which unbalanced expression of various combinations of genes affecting TB invasion provoke disease onset.

The long noncoding RNA uc.294 is upregulated in early-onset pre-eclampsia and inhibits proliferation, invasion of trophoblast cells (HTR-8/SVneo)

Recently, a large number of long noncoding RNAs (lncRNAs) have been reported in human diseases that are evolutionarily conserved and are likely to play a role in many biological events including pre-eclampsia. In our previous research, we selected thousands of lncRNAs for their relationship with early-onset pre-eclampsia. Among these lncRNAs, a lncRNA named uc.294 attracted our attention, was once reported to specifically be expressed at a high level in the early-onset of pre-eclampsia. This study aims to investigate the function of uc.294 in early-onset pre-eclampsia and the possible mechanism. The uc.294 expression level in early-onset pre-eclampsia or in normal placenta tissues was evaluated by quantitative real-time polymerase chain reaction. To detect the proliferation, invasion, and apoptosis capacity of the trophoblast cells, we performed the Cell Counting Kit-8 assay, transwell assay, and flow cytometry, respectively. Here we report, for the first time, that uc.294 inhibits proliferation, invasion, and promotes apoptosis of trophoblast cells HTR-8/SVneo by working in key aspects of biological behaviors. However, how uc.294 acts to regulate gene functions in early-onset pre-eclampsia needs further exploration.

Hypoxia and Placental Development

Hemochorial placentation is orchestrated through highly regulated temporal and spatial decisions governing the fate of trophoblast stem/progenitor cells. Trophoblast cell acquisition of specializations facilitating invasion and uterine spiral artery remodeling is a labile process, sensitive to the environment, and represents a process that is vulnerable to dysmorphogenesis in pathologic states. Hypoxia is a signal guiding placental development, and molecular mechanisms directing cellular adaptations to low oxygen tension are integral to trophoblast cell differentiation and placentation. Hypoxia can also be used as an experimental tool to investigate regulatory processes controlling hemochorial placentation. These developmental processes are conserved in mouse, rat, and human placentation. Consequently, elements of these developmental events can be modeled and hypotheses tested in trophoblast stem cells and in genetically manipulated rodents. Hypoxia is also a consequence of a failed placenta, yielding pathologies that can adversely affect maternal adjustments to pregnancy, fetal health, and susceptibility to adult disease. The capacity of the placenta for adaptation to environmental challenges highlights the importance of its plasticity in safeguarding a healthy pregnancy. Birth Defects Research 109:1309-1329, 2017.© 2017 Wiley Periodicals, Inc.

Compromised JMJD6 Histone Demethylase Activity Affects VHL Gene Repression in Preeclampsia

CONTEXT

The von Hippel Lindau (VHL) protein is a key executor of the cellular hypoxic response that is compromised in preeclampsia, a serious disorder complicating 5% to 7% of pregnancies. To date, the mechanisms controlling VHL gene expression in the human placenta remain elusive.

OBJECTIVE

We examined VHL epigenetic regulation in normal pregnancy and in preeclampsia, a pathology characterized by placental hypoxia.

DESIGN, SETTING, AND PARTICIPANTS

Placentae were obtained from early-onset preeclampsia (n = 56; <34 weeks of gestation) and late-onset preeclampsia (n = 19; ≥34 weeks of gestation). Placentae from healthy normotensive age-matched preterm control (n = 43) and term control (n = 23) pregnancies were included as controls.

MAIN OUTCOME MEASURE(S)

We measured the activity of Jumonji domain containing protein 6 (JMJD6), a ferrous iron (Fe2+)- and oxygen-dependent histone demethylase, and examined its function in the epigenetic control of VHL.

RESULTS

JMJD6 regulates VHL gene expression in the human placenta. VHL downregulation in preeclampsia is dependent on decreased JMJD6 demethylase activity due to hypoxia and reduced Fe2+ bioavailability. Chromatin immunoprecipitation assays revealed decreased association of JMJD6 and its histone targets with the VHL promoter. Findings in preeclampsia were corroborated in a murine model of pharmacological hypoxia using FG-4592. Placentae from FG-4592-treated mice exhibited reduced VHL levels, accompanied by placental morphological alterations and reduced pup weights. Notably, Fe2+ supplementation rescued JMJD6 histone demethylase activity in histone from E-PE and FG-4592-treated mice.

CONCLUSIONS

Our study uncovers epigenetic regulation of VHL and its functional consequences for altered oxygen and iron homeostasis in preeclampsia.

Ceramide-induced BOK promotes mitochondrial fission in preeclampsia

Mitochondria are in a constant balance of fusing and dividing in response to cellular cues. Fusion creates healthy mitochondria, whereas fission results in removal of non-functional organelles. Changes in mitochondrial dynamics typify several human diseases. However, the contribution of mitochondrial dynamics to preeclampsia, a hypertensive disorder of pregnancy characterized by placental cell autophagy and death, remains unknown. Herein, we show that the mitochondrial dynamic balance in preeclamptic placentae is tilted toward fission (increased DRP1 expression/activation and decreased OPA1 expression). Increased phosphorylation of DRP1 (p-DRP1) in mitochondrial isolates from preeclamptic placentae and transmission electron microscopy corroborated augmented mitochondrial fragmentation in cytotrophoblast cells of PE placentae. Increased fission was accompanied by build-up of ceramides (CERs) in mitochondria from preeclamptic placentae relative to controls. Treatment of human choriocarcinoma JEG3 cells and primary isolated cytrophoblast cells with CER 16:0 enhanced mitochondrial fission. Loss- and gain-of-function experiments showed that Bcl-2 member BOK, whose expression is increased by CER, positively regulated p-DRP1/DRP1 and MFN2 expression, and localized mitochondrial fission events to the ER/MAM compartments. We also identified that the BH3 and transmembrane domains of BOK were vital for BOK regulation of fission. Moreover, we found that full-length PTEN-induced putative kinase 1 (PINK1) and Parkin, were elevated in mitochondria from PE placentae, implicating mitophagy as the process that degrades excess mitochondria fragments produced from CER/BOK-induced fission in preeclampsia. In summary, our study uncovered a novel CER/BOK-induced regulation of mitochondrial fission and its functional consequence for heightened trophoblast cell autophagy in preeclampsia.

Factor inhibiting HIF1-A novel target of SUMOylation in the human placenta

Adaptations to changes in oxygen are critical to ensure proper placental development, and impairments in oxygen sensing mechanisms characterize placental pathologies such as preeclampsia. In this study, we examined the involvement of SUMOylation, a reversible posttranslational modification, in the regulation of the asparaginyl hydroxylase Factor Inhibiting Hypoxia Inducible Factor 1 (FIH1) in the human placenta in development and in disease status. FIH1 protein abundance and spatial distribution in the developing placenta directly correlated with oxygen tension in vivo. Immunofluorescence analysis showed that early on FIH1 primarily localized to nuclei of cytotrophoblast cells, while after 10 weeks of gestation it was present in nuclei and cytoplasm of both cytotrophoblast and syncytiotrophoblast cells. Exposure of choriocarcinoma JEG-3 cells to hypoxia induced FIH1 SUMOylation by promoting its association to SUMO2/3. Transfection of JEG-3 cells with FIH1 constructs containing SUMO-mutated sites revealed that SUMOylation of FIH1 by SUMO2/3 targeted it for proteasomal degradation, particularly in hypoxia. SUMOylation of FIH1 directly impacted on HIF1A activity as determined by HIF-responsive luciferase assay. Co-immunoprecipitation analyses revealed enhanced FIH1-SUMO2/3 associations early in development, when FIH1 levels are low, while deSUMOylation of FIH1 by SENP3 increased later in gestation, when FIH1 levels are rising. In preeclampsia, decreased FIH1 protein expression associated with impaired deSUMOylation by SENP3 and increased association with the ubiquitin ligase RNF4. We propose a novel mode of regulation of FIH1 stability by dynamic SUMOylation and deSUMOylation in the human placenta in response to changing oxygen tension, thereby mediating HIF1A transcriptional activity in physiological and pathological conditions.

Elevating VEGF-A and PDGF-BB secretion by salidroside enhances neoangiogenesis in diabetic hind-limb ischemia

Hind-limb ischemia (HLI) is one of the major complication of diabetic patients. Angiogenesis potential in diabetic patients is severely disrupted, and the mechanism underlying it has not been fully elucidated, making it an obstacle for developing an efficient therapeutic angiogenesis strategy. Skeletal muscle cells, through their paracrine function, had been known to be critical for neoangiogenesis. Here we found that hyperglycemia upregulates the expression of skeletal muscle cells prolyl hydroxylase domain 3 (PHD3), which resulted in the decrease of the secretion of angiogenic factors, especially VEGF-A and PDGF-BB. We showed that treatment with salidroside, a small molecule drug, significantly suppresses PHD3 expression and increases VEGF-A and PDGF-BB secretion from skeletal muscle cells, which in turn enhances the proliferation and migration potentials of endothelial and smooth muscle cells. Finally, we demonstrated that intramuscular injection of salidroside into the ischemic hind limbs of diabetic HLI model mice could efficiently induce neoangiogenesis and blood perfusion recovery. Thus, our novel findings not only reveal the effects of hyperglycemia on the angiogenesis potential of skeletal muscle cells and the mechanism underlying it, but also provides a novel finding suggesting that salidroside might be a potential small molecule drug for diabetic HLI.

A Single Sphingomyelin Species Promotes Exosomal Release of Endoglin into the Maternal Circulation in Preeclampsia

Preeclampsia (PE), an hypertensive disorder of pregnancy, exhibits increased circulating levels of a short form of the auxillary TGF-beta (TGFB) receptor endoglin (sENG). Until now, its release and functionality in PE remains poorly understood. Here we show that ENG selectively interacts with sphingomyelin(SM)-18:0 which promotes its clustering with metalloproteinase 14 (MMP14) in SM-18:0 enriched lipid rafts of the apical syncytial membranes from PE placenta where ENG is cleaved by MMP14 into sENG. The SM-18:0 enriched lipid rafts also contain type 1 and 2 TGFB receptors (TGFBR1 and TGFBR2), but not soluble fms-like tyrosine kinase 1 (sFLT1), another protein secreted in excess in the circulation of women with PE. The truncated ENG is then released into the maternal circulation via SM-18:0 enriched exosomes together with TGFBR1 and 2. Such an exosomal TGFB receptor complex could be functionally active and block the vascular effects of TGFB in the circulation of PE women.

Systematic Characterization of Autophagy in Gestational Diabetes Mellitus

Autophagy is a dynamic process that degrades and recycles cellular organelles and proteins to maintain cell homeostasis. Alterations in autophagy occur in various diseases; however, the role of autophagy in gestational diabetes mellitus (GDM) is unknown. In the present study, we characterized the roles and functions of autophagy in GDM patient samples and extravillous trophoblasts cultured with glucose. We found significantly enhanced autophagy in GDM patients. Moreover, high glucose levels enhanced autophagy and cell apoptosis, reducing proliferation and invasion, and these effects were ameliorated through knockdown of ATG5. Genome-wide 5-hydroxymethylcytosine data analysis further revealed the epigenomic regulatory circuitry underlying the induced autophagy and apoptosis in GDM and preeclampsia. Finally, RNA sequencing was performed to identify gene expression changes and critical signaling pathways after silencing of ATG5. Our study has demonstrated the substantial functions of autophagy in GDM and provides potential therapeutic targets for the treatment of GDM patients.

Placental Origins of Chronic Disease

Epidemiological evidence links an individual's susceptibility to chronic disease in adult life to events during their intrauterine phase of development. Biologically this should not be unexpected, for organ systems are at their most plastic when progenitor cells are proliferating and differentiating. Influences operating at this time can permanently affect their structure and functional capacity, and the activity of enzyme systems and endocrine axes. It is now appreciated that such effects lay the foundations for a diverse array of diseases that become manifest many years later, often in response to secondary environmental stressors. Fetal development is underpinned by the placenta, the organ that forms the interface between the fetus and its mother. All nutrients and oxygen reaching the fetus must pass through this organ. The placenta also has major endocrine functions, orchestrating maternal adaptations to pregnancy and mobilizing resources for fetal use. In addition, it acts as a selective barrier, creating a protective milieu by minimizing exposure of the fetus to maternal hormones, such as glucocorticoids, xenobiotics, pathogens, and parasites. The placenta shows a remarkable capacity to adapt to adverse environmental cues and lessen their impact on the fetus. However, if placental function is impaired, or its capacity to adapt is exceeded, then fetal development may be compromised. Here, we explore the complex relationships between the placental phenotype and developmental programming of chronic disease in the offspring. Ensuring optimal placentation offers a new approach to the prevention of disorders such as cardiovascular disease, diabetes, and obesity, which are reaching epidemic proportions.

Augmented trophoblast cell death in preeclampsia can proceed via ceramide-mediated necroptosis

Preeclampsia, a serious hypertensive disorder of pregnancy, is characterized by elevated ceramide (CER) content that is responsible for heightened trophoblast cell death rates via apoptosis and autophagy. Whether trophoblast cells undergo necroptosis, a newly characterized form of regulated necrosis, and the potential role of CER in this process remain to be established. Herein, we report that exposure of both JEG3 cells and primary isolated cytotrophoblasts to C16:0 CER in conjunction with a caspase-8 inhibitor (Q-VD-OPh) promoted necroptotic cell death, as evidenced by increased expression and association of receptor-interacting protein kinases RIP1 and RIP3, as well as phosphorylation of mixed lineage kinase domain-like (MLKL) protein. MLKL activation and oligomerization could be abrogated by pretreatment with the necroptosis inhibitor necrostatin-1 (Nec-1). CER+Q-VD-OPH-treated primary trophoblasts displayed striking necrotic morphology along with disrupted fusion processes as evidenced by maintenance of E-cadherin-stained membrane boundaries and reduced glial cell missing-1 expression, but these events were effectively reversed using Nec-1. Of clinical relevance, we established an increased susceptibility to necroptotic cell death in preeclamptic placentae relative to normotensive controls. In preeclampsia, increased necrosome (RIP1/RIP3) protein levels, as well as MLKL activation and oligomerization associated with necrotic cytotrophoblast morphology. In addition, caspase-8 activity was reduced in severe early-onset preeclampsia cases. This study is the first to report that trophoblast cells undergo CER-induced necroptotic cell death, thereby contributing to the increased placental dysfunction and cell death found in preeclampsia.

Ursolic acid sensitizes radioresistant NSCLC cells expressing HIF-1α through reducing endogenous GSH and inhibiting HIF-1α

In previous studies, the present authors demonstrated that effective sensitization of ionizing radiation-induced death of tumor cells, including non-small cell lung cancer (NSCLC) cells, could be produced by oleanolic acid (OA), a pentacyclic triterpenoid present in plants. In the present study, it was investigated whether ursolic acid (UA), an isomer of OA, had also the capacity of sensitizing radioresistant NSCLC cells. The radioresistant cell line H1299/M-hypoxia inducible factor-1α (HIF-1α) was established by transfection with a recombinant plasmid expressing mutant HIF-1α (M-HIF-1α). Compared with parental H1299 cells and H1299 cells transfected with empty plasmid, H1299/M-HIF-1α cells had lower radiosensitivity. Following the use of UA to treat NSCLC cells, elevation of the radiosensitivity of cells was observed by MTT assay. The irradiated H1299/M-HIF-1α cells were more sensitive to UA pretreatment than the irradiated cells with empty plasmid and control. The alteration of DNA damage in the irradiated cells was further measured using micronucleus (MN) assay. The combination of UA treatment with radiation could induce the increase of cellular MN frequencies, in agreement with the change in the tendency observed in the cell viability assay. It was further shown that the endogenous glutathione (GSH) contents were markedly attenuated in the differently irradiated NSCLC cells with UA (80 µmol/l) pretreatment through glutathione reductase/5,5'-dithiobis-(2-nitrob-enzoic acid) (DTNB) recycling assay. The results revealed that UA treatment alone could effectively decrease the GSH content in H1299/M-HIF-1α cells. In addition, the inhibition of HIF-1α expression in radioresistant cells was confirmed by western blotting. It was then concluded that UA could upregulate the radiosensitivity of NSCLC cells, and in particular reduce the refractory response of cells expressing HIF-1α to ionizing radiation. The primary mechanism is associated with reduction of endogenous GSH and inhibition of high expression of intracellular HIF-1α. UA should therefore be deeply studied as a potential radiosensitizing reagent for NSCLC radiotherapy.