Autophagy in the placenta of women with hypertensive disorders in pregnancy

Cadmium exposure activates mitophagy through downregulating thyroid hormone receptor/PGC1α signal in preeclampsia

Gestational cadmium exposure increases the risk of preeclampsia. Placenta mitophagy was activated in preeclampsia. The aim of present study was to explore the mechanism of cadmium-induced mitophagy activation and its association with preeclampsia. Mitophagy markers expression levels were detected by quantitative real-time PCR, Western blot, immunofluorescence and immunochemistry in preeclampsia placenta. JEG3 cells were treated with CdCl2, iopanoic acid (IOP), 3-methyladenine and PGC1α SiRNA to verify mechanism of cadmium-induced mitophagy. Mitophagy marker LC3BII/I and P62 expression were increased and mitochondrial membrane receptor protein TOM20 and FUNDC1 expression were decreased in preeclampsia placenta as compared with that in normotension control. Mitophagy marker LC3BII/I and P62 expression were increased and TOM20 and FUNDC1 expression was decreased in CdCl2-treated JEG3 cells. Meanwhile, mitochondrial biogenesis regulator, PGC1α expression was decreased in preeclampsia and CdCl2-treated JEG3 cells. The expressions of LC3B and P62 were increased and the expressions of TOM20, FUNDC1 and PGC1α were decreased in IOP-treated cell. PGC1α SiRNA transfection led to increased expression of LC3BII/I and P62 and decreased expression of TOM20 and FUNDC1. The expression of sFlt1 was increased in preeclampsia placenta, CdCl2-treated cells, in IOP-treated cells and in PGC1α SiRNA transfected cells. 3-methyladenine treatment protected the increased expression of sFlt1 in CdCl2-treated cells, in IOP-treated cells and in PGC1α SiRNA transfected cells. Meanwhile, co-treatment of cadmium and IOP or PGC1αSiRNA led to a reduce expressions of OPA1, MFN1, MFN2 and FUNDC1 as compared to cadmium-treated, IOP-treated and PGC1α SiRNA-treated cells. These results elucidated that maternal cadmium exposure activated placenta mitophagy through downregulation of thyroid hormone receptor signal mediated decreased expression of PGC1α and was associated with the occurrence of preeclampsia.

The regulated cell death at the maternal-fetal interface: beneficial or detrimental?

Regulated cell death (RCD) plays a fundamental role in placental development and tissue homeostasis. Placental development relies upon effective implantation and invasion of the maternal decidua by the trophoblast and an immune tolerant environment maintained by various cells at the maternal-fetal interface. Although cell death in the placenta can affect fetal development and even cause pregnancy-related diseases, accumulating evidence has revealed that several regulated cell death were found at the maternal-fetal interface under physiological or pathological conditions, the exact types of cell death and the precise molecular mechanisms remain elusive. In this review, we summarized the apoptosis, necroptosis and autophagy play both promoting and inhibiting roles in the differentiation, invasion of trophoblast, remodeling of the uterine spiral artery and decidualization, whereas ferroptosis and pyroptosis have adverse effects. RCD serves as a mode of communication between different cells to better maintain the maternal-fetal interface microenvironment. Maintaining the balance of RCD at the maternal-fetal interface is of utmost importance for the development of the placenta, establishment of an immune microenvironment, and prevention of pregnancy disorders. In addition, we also revealed an association between abnormal expression of key molecules in different types of RCD and pregnancy-related diseases, which may yield significant insights into the pathogenesis and treatment of pregnancy-related complications.

The cGAS-STING pathway promotes the development of preeclampsia by upregulating autophagy: Mechanisms and implications

OBJECTIVE

To investigate the influence and significance of cGAS-STING signaling pathway and autophagy on the occurrence and development of preeclampsia.

DESIGN

A case-control experimental study, in vitro cell culture study, and in vivo animal research.

METHODS

Human placenta tissue was collected and the differences in HE staining were observed. Immunohistochemistry and Western blot were used to verify differences in cGAS, STING and autophagy associated proteins. The PE rat model was established, the pathological changes of placenta and kidney were observed by HE staining, and the expression levels of related proteins were detected. In the lv-STING transfected HTR-8/SVneo trophoblast cell model, the expressions of autophagy indexes such as P62 and LC3 were verified by RT-PCR, Western blot and cell fluorescence experiments, and then the invasion and migration ability of cells were detected by Transwell and scrape tests. As an effective STING antagonist, C176 was administered to PE rats to observe whether it was effective in the treatment of PE disease.

RESULTS

The expression levels of cGAS, STING and autophagy related proteins were increased in human and rat placental tissues. In the HTR-8/SVneo cell model which transfected by lv-STING, the expression levels of autophagy related indicators such as P62 and LC3 were increased. The invasion and migration ability of HTR-8/SVneo cells were significantly inhibited, which was improved by the autophagy inhibitor chloroquine. Acting as an effective STING antagonist in vivo, C176 significantly reversed the outcome of PE, alleviated and prevented the occurrence and development of PE.

CONCLUSION

Our study proved that the cGAS-STING signaling pathway and autophagy levels are elevated in preeclampsia disease, and the cGAS-STING signaling pathway promotes the occurrence and development of preeclampsia through up-regulation of autophagy. This finding provides new insights into the pathogenesis of preeclampsia. Targeting this pathway may provide a potential therapeutic strategy for the treatment of preeclampsia.

Exploring the Importance of Differential Expression of Autophagy Markers in Term Placentas from Late-Onset Preeclamptic Pregnancies

Preeclampsia (PE) is a serious hypertensive disorder affecting 4-5% of pregnancies globally, leading to maternal and perinatal morbidity and mortality and reducing life expectancy in surviving women post-gestation. Late-onset PE (LO-PE) is a clinical type of PE diagnosed after 34 weeks of gestation, being less severe than the early-onset PE (EO-PE) variant, although both entities have a notable impact on the placenta. Despite the fact that most studies have focused on EO-PE, LO-PE does not deserve less attention since its prevalence is much higher and little is known about the role of the placenta in this pathology. Via RT-qPCR and immunohistochemistry methods, we measured the gene and protein expressions of several macroautophagy markers in the chorionic villi of placentas from women who underwent LO-PE (n = 68) and compared them to normal pregnancies (n = 43). We observed a markedly distinct expression pattern, noticing a significant drop in NUP62 expression and a considerable rise in the gene and protein expressions of ULK1, ATG9A, LC3, ATG5, STX-17, and LAMP-1 in the placentas of women with LO-PE. A major induction of autophagic processes was found in the placental tissue of patients with LO-PE. Abnormal signaling expression of these molecular patterns in this condition aids in the understanding of the complexity of pathophysiology and proposes biomarkers for the clinical management of these patients.

Oxidative stress induces release of mitochondrial DNA into the extracellular space in human placental villous trophoblast BeWo cells

Circulating cell-free mitochondrial DNA (ccf-mtDNA) is an indicator of cell death, inflammation, and oxidative stress. ccf-mtDNA differs in pregnancies with placental dysfunction from healthy pregnancies and the direction of this difference depends on gestational age and method of mtDNA quantification. Reactive oxygen species (ROS) trigger release of mtDNA from non-placental cells; yet it is unknown whether trophoblast cells release mtDNA in response to oxidative stress, a common feature of pregnancies with placental pathology. We hypothesized that oxidative stress would induce cell death and release of mtDNA from trophoblast cells. BeWo cells were treated with antimycin A (10-320 μM) or rotenone (0.2-50 μM) to induce oxidative stress. A multiplex real-time quantitative PCR (qPCR) assay was used to quantify mtDNA and nuclear DNA in membrane bound, non-membrane bound, and vesicular-bound forms in cell culture supernatants and cell lysates. Treatment with antimycin A increased ROS (p<0.0001), induced cell necrosis (p=0.0004) but not apoptosis (p=0.6471) and was positively associated with release of membrane-bound and non-membrane bound mtDNA (p<0.0001). Antimycin A increased mtDNA content in exosome-like extracellular vesicles (vesicular-bound form; p=0.0019) and reduced autophagy marker expression (LC3A/B, p=0.0002; p62, p<0.001). Rotenone treatment did not influence mtDNA release or cell death (p>0.05). Oxidative stress induces release of mtDNA into the extracellular space and causes non-apoptotic cell death and a reduction in autophagy markers in BeWo cells, an established in vitro model of human trophoblast cells. Intersection between autophagy and necrosis may mediate the release of mtDNA from the placenta in pregnancies exposed to oxidative stress.

NEW & NOTEWORTHY

This is the first study to test whether trophoblast cells release mitochondrial DNA in response to oxidative stress and to identify mechanisms of release and biological forms of mtDNA from this cellular type. This research identifies potential cellular mechanisms that can be used in future investigations to establish the source and biomarker potential of circulating mitochondrial DNA in preclinical experimental models and humans.

Protein Misfolding in Pregnancy: Current Insights, Potential Mechanisms, and Implications for the Pathogenesis of Preeclampsia

Protein misfolding disorders are a group of diseases characterized by supra-physiologic accumulation and aggregation of pathogenic proteoforms resulting from improper protein folding and/or insufficiency in clearance mechanisms. Although these processes have been historically linked to neurodegenerative disorders, such as Alzheimer's disease, evidence linking protein misfolding to other pathologies continues to emerge. Indeed, the deposition of toxic protein aggregates in the form of oligomers or large amyloid fibrils has been linked to type 2 diabetes, various types of cancer, and, in more recent years, to preeclampsia, a life-threatening pregnancy-specific disorder. While extensive physiological mechanisms are in place to maintain proteostasis, processes, such as aging, genetic factors, or environmental stress in the form of hypoxia, nutrient deprivation or xenobiotic exposures can induce failure in these systems. As such, pregnancy, a natural physical state that already places the maternal body under significant physiological stress, creates an environment with a lower threshold for aberrant aggregation. In this review, we set out to discuss current evidence of protein misfolding in pregnancy and potential mechanisms supporting a key role for this process in preeclampsia pathogenesis. Improving our understanding of this emerging pathophysiological process in preeclampsia can lead to vital discoveries that can be harnessed to create better diagnoses and treatment modalities for the disorder.

Autophagy-related biomarkers in preeclampsia: the underlying mechanism, correlation to the immune microenvironment and drug screening

BACKGROUND

Preeclampsia is a life-threatening disease of pregnancy that lacks effective pharmaceuticals which can target its pathogenesis. Since preeclampsia involves complex pathological processes, including autophagy, this study aims to explore autophagy-related mechanisms of preeclampsia and to screen potential drugs.

METHODS

Firstly, the datasets GSE75010, GSE24129, GSE66273, and autophagic genes lists were downloaded from public databases. Then, a weighted gene co-expression network analysis (WGCNA) was applied to filter autophagic-related hub genes of preeclampsia. The differential expression levels of the hub genes were validated with datasets GSE24129 and GSE66273. Next, the GO and KEGG enrichment, protein-protein interacting (PPI) network, as well as the downstream pathways was analyzed via the starBase, STRING and Cytoscape to determine the functions and regulatory network of the hub genes. Additionally, the immune microenvironment of preeclampsia was investigated by the CIBERSORTX database. Finally, three herb ingredients, berberine, baicalein, and luteolin were screened by molecular docking in comparison to pravastatin, metformin, and aspirin, to predict potential drugs for treating preeclampsia.

RESULTS

A total of 54 autophagy-related genes were filtered by WGCNA. After filtering with |GS| > 0.5 and |MM| > 0.8, three hub genes, namely PKM, LEP, and HK2, were identified and validated. Among these genes, PKM and LEP were overexpressed in women older than 35 years old ( p<0.05; p<0.05); the expression of PKM, LEP, and HK2 differed remarkably in women with different BMI (all p<0.05); PKM overexpressed in women with hypertension (p<0.05). The regulatory network of hub genes demonstrated that they were mainly enriched in metabolic pathways, including the AMPK signaling pathway, glucagon signaling pathway, adipocytokine signaling pathway, and central carbon metabolism. Then, immune microenvironment analysis turned out that M2 macrophages were reduced in preeclampsia women (p<0.0001) and were negatively correlated with the expression of PKM (r=-0.2, p<0.05), LEP (r=-0.4, p<0.0001), and HK2 (r=-0.3, p<0.001). Lastly, molecular docking showed baicalein and luteolin could bind intimately to hub genes.

CONCLUSION

PKM, LEP, and HK2 could be promising biomarkers for preeclampsia, which might regulate the pathogenesis of preeclampsia via metabolism pathways and immune microenvironment. Baicalein and luteolin could be potential therapeutics for preeclampsia.

The targeting of DAPK1 with miR-190a-3p promotes autophagy in trophoblast cells

Pre-eclampsia (PE) is a dangerous pathological status that occurs during pregnancy and is a leading reason for both maternal and fetal death. Autophagy is necessary for cellular survival in the face of environmental stress as well as cellular homeostasis and energy management. Aberrant microRNA (miRNA) expression is crucial in the pathophysiology of PE. Although studies have shown that miRNA (miR)-190a-3p function is tissue-specific, the precise involvement of miR-190a-3p in PE has yet to be determined. We discovered that miR-190a-3p was significantly lower and death-associated protein kinase 1 (DAPK1) was significantly higher in PE placental tissues compared to normal tissues, which is consistent with the results in cells. The luciferase analyses demonstrated the target-regulatory relationship between miR-190a-3p and DAPK1. The inhibitory effect of miR-190a-3p on autophagy was reversed by co-transfection of si-DAPK1 and miR-190a-3p inhibitors. Thus, our data indicate that the hypoxia-dependent miR-190a-3p/DAPK1 regulatory pathway is implicated in the development and progression of PE by promoting autophagy in trophoblast cells.

Vital role of autophagy flux inhibition of placental trophoblast cells in pregnancy disorders induced by HEV infection

Hepatitis E virus (HEV) has become one of the important pathogens that threaten the global public health. Type 3 and 4 HEV are zoonotic, which can spread vertically and cause placental damage. At the same time, autophagy plays an important role in the process of embryo development and pregnancy maintenance. However, the relationship between HEV and autophagy, especially in the placenta tissue, has not been clarified. We found lower litter rates in HEV-infected female mice, with significant intrauterine abortion of the embryo (24.19%). To explore the effects of HEV infection on placenta autophagy, chorionic cells (JEG-3) and mice placenta have been employed as research objects, while the expression of autophagy-related proteins (ATGs) has been detected in JEG-3 cells with different times of HEV inoculation. The results demonstrated that the expression of protein LC3 decreased and p62 accumulated, meanwhile ATGs such as ATG4B, ATG5, and ATG9A in JEG-3 cells have decreased significantly. In addition, the maturation of autophagosomes, which referred to the process of the combination of autophagosomes and lysosomes was prevented by HEV infection as well. All processes of autophagic flux, which include the initiation, development, and maturation three stages, were suppressed in JEG-3 cells after HEV infection. Similarly, the protein and gene expression of LC3 were significantly decreased in the placenta of pregnant mice with HEV infection. In summary, our results suggested that HEV inhibited autophagy in JEG-3 cells and placenta of pregnant mice, which might be the important pathogenic mechanisms of HEV infection leading to embryo abortion.

The Role of Sirtuin-1 (SIRT1) in the Physiology and Pathophysiology of the Human Placenta

Sirtuins, especially SIRT1, play a significant role in regulating inflammatory response, autophagy, and cell response to oxidative stress. Since their discovery, sirtuins have been regarded as anti-ageing and longevity-promoting enzymes. Sirtuin-regulated processes seem to participate in the most prevalent placental pathologies, such as pre-eclampsia. Furthermore, more and more research studies indicate that SIRT1 may prevent pre-eclampsia development or at least alleviate its manifestations. Having considered this, we reviewed recent studies on the role of sirtuins, especially SIRT1, in processes determining normal or abnormal development and functioning of the placenta.

Impact of ferroptosis on preeclampsia: A review

Preeclampsia (PE) is usually associated with the accumulation of reactive oxygen species (ROS) resulting from heightened oxidative stress (OS). Ferroptosis is a unique type of lipid peroxidation-induced iron-dependent cell death distinct from traditional apoptosis, necroptosis, and pyroptosis and most likely contributes considerable to PE pathogenesis. At approximately 10-12 weeks of gestation, trophoblasts create an environment rich in oxygen and iron. In patients with PE, ferroptosis-related genes such as HIF1 and MAPK8 are downregulated, whereas PLIN2 is upregulated. Furthermore, miR-30b-5p overexpression inhibits solute carrier family 11 member 2, resulting in a decrease in glutathione levels and an increase in the labile iron pool. At the maternal-fetal interface, physiological hypoxia/reperfusion and excessive iron result in lipid peroxidation and ROS production. Owing to the high expression of Fpn and polyunsaturated fatty acid-containing phospholipid-related enzymes, including acyl-CoA synthetase long-chain family member 4, lysophosphatidylcholine acyl-transferase 3, and spermidine/spermine N1-acetyltransferase 1, trophoblasts become more susceptible to OS and ROS damage. In stage 1, the injured trophoblasts exhibit poor invasion and incomplete uterine spiral artery remodeling caused by ferroptosis, leading to placental ischemia and hypoxia. Subsequently, ferroptosis marked by OS occurs in stage 2, eventually causing PE. We aimed to explore the new therapeutic target of PE through OS in ferroptosis.

Nitroxide-HMP-Protects Human Trophoblast HTR-8/SVneo Cells from H2O2-Induced Oxidative Stress by Reducing the HIF1A Signaling Pathway

Preeclampsia (PE) is a pregnancy-specific syndrome affecting 5-7% of patients. There is no effective treatment available. Early abnormal placental development is associated with oxidative stress (OS) and a release of reactive oxygen species (ROS) in the placenta. This phenomenon leads to downstream signaling, Hypoxia Inducible Factor 1A (HIF1A) stabilization and transcription of the anti-angiogenic factors soluble fms-like tyrosine kinase 1 (sFLT1) and soluble endoglin (sEng), which are known to cause endothelial and trophoblast dysfunction and cardinal features of PE: hypertension, proteinuria and, in severe cases, eclampsia. We tested whether 3-(Hydroxymethyl)-1-oxy-2,2,5,5-tetramethylpyrrolidine (HMP)-a nitroxide-type antioxidant molecule-can reduce placental OS and mitigate PE symptoms in vitro. We induced OS in human trophoblast (HTR-8/SVneo) cells with hydrogen peroxide (H2O2) and assessed whether modulating cell redox function with HMP reduces cell injury, mitochondrial stress and HIF1A and sFLT1 production. Pre-treatment with HMP reduced mitochondrial-derived ROS production, restored LC3B expression and reduced HIF1A and sFLT1 expression in H2O2-exposed HTR-8/SVneo trophoblast cells. HMP improved the mitochondrial electron chain enzyme activity, indicating that a reduction in OS alleviates mitochondrial stress and also reduces anti-angiogenic responses. In reducing placental trophoblast OS, HMP presents a potential novel therapeutic approach for the treatment of PE. Future investigation is warranted regarding the in vivo use of HMP.

Autophagy-mediated immune system regulation in reproductive system and pregnancy-associated complications

Autophagy lysosomal degradation is the main cell mechanism in cellular, tissue and organismal homeostasis and is controlled by autophagy-related genes (ATG). Autophagy has important effects in cellular physiology, including adaptation to metabolic stress, removal of dangerous cargo (such as protein aggregates, damaged organelles, and intracellular pathogens), regeneration during differentiation and development, and prevention of genomic damage in general. Also, it has been found that autophagy is essential for pre-implantation, development, and maintaining embryo survival in mammals. Under certain conditions, autophagy may be detrimental through pro-survival effects such as cancer progression or through possible cell death-promoting effects. Hormonal changes and environmental stress can initiate autophagy in reproductive physiology. The activity of autophagy can be upregulated under conditions like a lack of nutrients, inflammation, hypoxia, and infections. In this regard the dysregulation of autophagy involved in some pregnancy complications such as preeclampsia (PE) and pregnancy loss, and has a major impact on reproductive outcomes. Therefore, we aimed to discuss the relationship between autophagy and the female reproductive system, with a special focus on the immune system, and its role in fetal and maternal health.

ANP promotes HTR-8/SVneo cell invasion by upregulating protein kinase N 3 via autophagy inhibition

Preeclampsia is a gestational disease characterized by two major pathological changes-shallow trophoblast invasion and impaired spiral artery remodeling. Atrial natriuretic peptide (ANP) is a kind of peptide hormone that regulates blood pressure, while the lack of active ANP participates in preeclampsia pathogenesis. However, the underlying mechanism of how ANP modulates trophoblasts function remains unclarified. Here, we performed isobaric tags for relative and absolute quantification (iTRAQ) in ANP-treated HTR-8/SVneo cells and identified Protein Kinase 3 (PKN3) as the downstream factor of ANP, which was downregulated in preeclamptic placenta. Chromatin immunoprecipitation analysis and luciferase assays showed that NFYA was one of the transcription factors for the PKN3 promoter, which was also regulated by ANP treatment in HTR-8/SVneo cells. Transmission electron microscopy and Western Blotting in HTR-8/SVneo cells indicated that ANP inhibited autophagy via AMPK-mTORC1 signaling, while excess autophagy was observed in preeclamptic placenta. The increased expression of PKN3 and enhanced cell invasion ability in HTR-8/SVneo cells induced by ANP could be abolished by autophagy activation or transfection with PKN3 shRNA or NFYA shRNA or NPR-A shRNA via regulating the invasion-related genes and the epithelial mesenchymal transition molecules. Our results demonstrated that ANP could enhance trophoblast invasion by upregulating PKN3 via NFYA promotion through autophagy inhibition in an AMPK/mTORC1 signaling-dependent manner.

The Role of Autophagy in the Female Reproduction System: For Beginners to Experts in This Field

Autophagy is a fundamental process involved in regulating cellular homeostasis. Autophagy has been classically discovered as a cellular process that degrades cytoplasmic components non-selectively to produce energy. Over the past few decades, this process has been shown to work in energy production, as well as in the reduction of excessive proteins, damaged organelles, and membrane trafficking. It contributes to many human diseases, such as neurodegenerative diseases, carcinogenesis, diabetes mellitus, development, longevity, and reproduction. In this review, we provide important information for interpreting results related to autophagic experiments and present the role of autophagy in this field.

Down-regulation of autophagy proteins is associated with higher mTOR expression in the placenta of pregnant women with preeclampsia

Autophagy is a lysosomal degradation pathway that removes protein aggregates and damaged organelles maintaining cellular integrity. It seems to be essential for cell survival during stress, starvation, hypoxia, and consequently to the placenta implantation and development. Preeclampsia (PE) is a multisystemic disorder characterized by the onset of hypertension associated or not with proteinuria and other maternal complications. Considering that the placenta seems to play an important role in the pathogenesis of PE, the objective of the present study was to evaluate protein levels of light chain protein (LC3), beclin-1, and the mammalian target of rapamycin (mTOR) in the placenta of pregnant women with PE. Placental tissues collected from 20 women with PE and 20 normotensive (NT) pregnant women were evaluated for LC3, beclin-1, and mTOR expression by qPCR and immunohistochemistry. The mRNA for LC3 and beclin-1 were significantly lower, while mTOR gene expression was significantly higher in the placenta of pregnant women with PE than in the NT group. Placentas of PE women showed significantly decreased protein expression of LC3-II and beclin-1, whereas mTOR was significantly increased compared with the NT pregnant women. There was a negative correlation between protein expression of mTOR and LC3-II in the placental tissue of PE women. In conclusion, the results showed autophagy deficiency suggesting that failure in this degradation process may contribute to the pathogenesis of PE; however, new studies involving cross-talk between autophagy and inflammatory molecular mechanisms might help to better understand the autophagy process in this obstetric pathology.

Homeostasis Maintenance in Plasmodium-Infected Placentas: Is There a Role for Placental Autophagy During Malaria in Pregnancy?

Malaria represents a significant public health burden to populations living in developing countries. The disease takes a relevant toll on pregnant women, who are more prone to developing severe clinical manifestations. Inflammation triggered in response to P. falciparum sequestration inside the placenta leads to physiological and structural changes in the organ, reflecting locally disrupted homeostasis. Altogether, these events have been associated with poor gestational outcomes, such as intrauterine growth restriction and premature delivery, contributing to the parturition of thousands of African children with low birth weight. Despite significant advances in the field, the molecular mechanisms that govern these outcomes are still poorly understood. Herein, we discuss the idea of how some housekeeping molecular mechanisms, such as those related to autophagy, might be intertwined with the outcomes of malaria in pregnancy. We contextualize previous findings suggesting that placental autophagy is dysregulated in P. falciparum-infected pregnant women with complementary research describing the importance of autophagy in healthy pregnancies. Since the functional role of autophagy in pregnancy outcomes is still unclear, we hypothesize that autophagy might be essential for circumventing inflammation-induced stress in the placenta, acting as a cytoprotective mechanism that attempts to ensure local homeostasis and better gestational prognosis in women with malaria in pregnancy.

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.

Preeclampsia: From Cellular Wellness to Inappropriate Cell Death, and the Roles of Nutrition

Preeclampsia is one of the most common obstetrical complications worldwide. The pathomechanism of this disease begins with abnormal placentation in early pregnancy, which is associated with inappropriate decidualization, vasculogenesis, angiogenesis, and spiral artery remodeling, leading to endothelial dysfunction. In these processes, appropriate cellular deaths have been proposed to play a pivotal role, including apoptosis and autophagy. The proper functioning of these physiological cell deaths for placentation depends on the wellbeing of the trophoblasts, affected by the structural and functional integrity of each cellular component including the cell membrane, mitochondria, endoplasmic reticulum, genetics, and epigenetics. This cellular wellness, which includes optimal cellular integrity and function, is heavily influenced by nutritional adequacy. In contrast, nutritional deficiencies may result in the alteration of plasma membrane, mitochondrial dysfunction, endoplasmic reticulum stress, and changes in gene expression, DNA methylation, and miRNA expression, as well as weakened defense against environmental contaminants, hence inducing a series of inappropriate cellular deaths such as abnormal apoptosis and necrosis, and autophagy dysfunction and resulting in abnormal trophoblast invasion. Despite their inherent connection, the currently available studies examined the functions of each organelle, the cellular death mechanisms and the nutrition involved, both physiologically in the placenta and in preeclampsia, separately. Therefore, this review aims to comprehensively discuss the relationship between each organelle in maintaining the physiological cell death mechanisms and the nutrition involved, and the interconnection between the disruptions in the cellular organelles and inappropriate cell death mechanisms, resulting in poor trophoblast invasion and differentiation, as seen in preeclampsia.

Overexpression of let-7b exerts beneficial effects on the functions of human placental trophoblasts by activating the ERK1/2 signaling pathway

The present work aimed to explore let-7b's molecular mechanisms that regulate the functions of placental trophoblasts and to examine placental let-7b expression in human pre-eclampsia (PE). Human trophoblast HTR-8/SVneo cells underwent transduction with control and let-7b overexpressing lentiviruses, respectively. Cell proliferation assessment utilized cell counting kit-8 (CCK-8) and 5-ethynyl-2'-deoxyuridine (EdU) assays. Apoptosis, autophagy, inflammation, epithelial-to-mesenchymal transition (EMT), and ERK1/2 signaling-associated proteins were assessed by immunoblot. Placental tissue samples were collected from women with normal pregnancy (n = 20) and PE patients (n = 14). Let-7b overexpression in HTR-8/SVneo cells remarkably induced cell proliferation and invasion, suppressed apoptosis and autophagy, and resulted in decreased tumor necrosis factorα (TNF-α) expression and increased interleukin 6 (IL-6) expression in trophoblasts. Notably, the beneficial effects of let-7b overexpression, including cell invasion and EMT, were largely reversed by treatment with U0126, an indirect ERK1/2 signaling inhibitor, in these cells. TGF-β receptor type-1 (TGFBR1) overexpression weakened let-7b's functions in ERK pathway activation and invasion in trophoblasts. Placental tissue specimens from PE cases demonstrated significantly lower let-7b expression compared with normal controls. Overexpression of let-7b exerts beneficial effects on the functions of human placental trophoblasts via ERK1/2 signaling, and placental let-7b is downregulated in human PE. These findings suggest let-7b is a promising biomarker for the prospective diagnosis and targeted therapy of PE.

Etiological Value of Sterile Inflammation in Preeclampsia: Is It a Non-Infectious Pregnancy Complication?

Understanding of sterile inflammation and its associated biological triggers and diseases is still at the elementary stage. This becomes more warranted in cases where infections are not associated with the pathology. Detrimental effects of bacterial and viral infections on the immune responses at the maternal-fetal interface as well as pregnancy outcomes have been well documented. However, an infection-induced etiology is not thought to be a major contributing component to severe pregnancy complications such as preeclampsia (PE) and gestational diabetes. How is then an inflammatory signal thought to be associated with these pregnancy complications? It is not clear what type of inflammation is involved in the onset of PE-like features. We opine that sterile inflammation regulated by the inflammasome-gasdermins-caspase-1 axis is a contributory factor to the onset of PE. We hypothesize that increased production and release of damage-associated molecular patterns (DAMPs) or Alarmins such as high-mobility group box1 (HMGB1), cell-free fetal DNA, uric acid, the NOD-like receptor pyrin-containing receptor 3 (NLRP3) inflammasome, IL-1β and IL-18 occur in the PE placenta. Some of these molecules have already been observed in the placenta from women with PE. Mechanistically, emerging evidence has demonstrated that excessive placental endoplasmic reticulum (ER) stress, impaired autophagy and gasdermine D (GSDMD)-mediated intrinsic pyroptosis are key events that contribute to systemic sterile inflammation in patients with PE, especially early-onset PE (e-PE). In this review, we highlight the advances on the roles of sterile inflammation and inflammatory signaling cascades involving ER stress, autophagy deficiency and pyroptosis in PE pathophysiology. Deciphering the mechanisms underlying these inflammatory pathways may provide potential diagnostic biomarkers and facilitate the development of therapeutic strategies to treat this devastating disease.

Cannabidiol disrupts apoptosis, autophagy and invasion processes of placental trophoblasts

Cannabidiol (CBD) is a constituent of Cannabis sativa without psychotropic activity, whose medical benefits have been recognised. However, little is known about the potential toxic effects of CBD on reproductive health. Placental development involves tightly controlled processes of cell proliferation, differentiation, apoptosis, autophagy and migration/invasion of trophoblast cells. Cannabis use by pregnant women has been increasing, mainly for the relief of nausea associated with the first trimester, which raises great concern. Regarding the crucial role of cytotrophoblast cells (CTs) and extravillous trophoblasts (EVTs) in placentation, the effects of CBD (1-10 µM) were studied, using in vitro model systems BeWo and HTR-8/SVneo cell lines, respectively. CBD causes cell viability loss in a dose-dependent manner, disrupts cell cycle progression and induces apoptosis through the mitochondrial pathway, on both cell models. Moreover, CBD induces autophagy only in HTR-8/SVneo cells, being this process a promoter of apoptosis. Hypoxia-responsive genes HIF1A and SPP1 were also increased in CBD-treated HTR-8/SVneo cells suggesting a role for HIF-1α in the apoptotic and autophagic processes. In addition, CBD was able to decrease HTR-8/SVneo cell migration. Therefore, CBD interferes with trophoblast turnover and placental remodelling, which can have a considerable impact on pregnancy outcome. Thus, from an in vitro perspective our study adds new evidence for the potential negative impact of cannabis use by pregnant women.

Ceramide-Induced Lysosomal Biogenesis and Exocytosis in Early-Onset Preeclampsia Promotes Exosomal Release of SMPD1 Causing Endothelial Dysfunction

Aberrant ceramide build-up in preeclampsia, a serious disorder of pregnancy, causes exuberant autophagy-mediated trophoblast cell death. The significance of ceramide accumulation for lysosomal biogenesis in preeclampsia is unknown. Here we report that lysosome formation is markedly increased in trophoblast cells of early-onset preeclamptic placentae, in particular in syncytiotrophoblasts. This is accompanied by augmented levels of transcription factor EB (TFEB). In vitro and in vivo experiments demonstrate that ceramide increases TFEB expression and nuclear translocation and induces lysosomal formation and exocytosis. Further, we show that TFEB directly regulates the expression of lysosomal sphingomyelin phosphodiesterase (L-SMPD1) that degrades sphingomyelin to ceramide. In early-onset preeclampsia, ceramide-induced lysosomal exocytosis carries L-SMPD1 to the apical membrane of the syncytial epithelium, resulting in ceramide accumulation in lipid rafts and release of active L-SMPD1 via ceramide-enriched exosomes into the maternal circulation. The SMPD1-containing exosomes promote endothelial activation and impair endothelial tubule formation in vitro. Both exosome-induced processes are attenuated by SMPD1 inhibitors. These findings suggest that ceramide-induced lysosomal biogenesis and exocytosis in preeclamptic placentae contributes to maternal endothelial dysfunction, characteristic of this pathology.

Excess fibronectin 1 participates in pathogenesis of pre-eclampsia by promoting apoptosis and autophagy in vascular endothelial cells

Plasma fibronectin 1 (FN1) levels are elevated in individuals with pre-eclampsia (PE), which may be applied as a possible b marker for vascular endothelial injury during PE. In the present study, the possible role of FN1 in the pathogenesis of PE and regulation of apoptosis and autophagy in vascular endothelial cells was explored. Plasma FN1 levels in 80 patients with PE and 40 healthy pregnant individuals were measured using ELISA to verify its relationship with the severity of PE. pcDNA3.1-FN1 or FN1-small interfering (si) RNA was used to manipulate the expression of FN1 in human umbilical vein endothelial cells (HUVECs) to assess the effects of FN1 on cell apoptosis, autophagy, and the phosphoinositide 3-kinase (PI3K)/protein kinase B (AKT)/mechanistic target of rapamycin (mTOR) signaling pathway. It was found that upregulation of FN1 promoted apoptosis and autophagy, in addition to significantly inhibiting the activation of AKT and mTOR in HUVECs. By contrast, downregulation of FN1 expression inhibited cell apoptosis and autophagy, but increased AKT and mTOR phosphorylation in HUVECs that were cultured in serum samples obtained from patients with PE. Rescue experiments found that the PI3K/AKT inhibitor LY294002 reversed the effects of FN1-siRNA on apoptosis and autophagy in HUVECs cultured in serum from patients with PE. Therefore, data from the present study suggest that FN1 participates in the pathogenesis of PE by promoting apoptosis and autophagy in vascular endothelial cells, which is associated with the PI3K/AKT/mTOR signaling pathway.

Autophagy Process in Trophoblast Cells Invasion and Differentiation: Similitude and Differences With Cancer Cells

Early human placental development begins with blastocyst implantation, then the trophoblast differentiates and originates the cells required for a proper fetal nutrition and placental implantation. Among them, extravillous trophoblast corresponds to a non-proliferating trophoblast highly invasive that allows the vascular remodeling which is essential for appropriate placental perfusion and to maintain the adequate fetal growth. This process involves different placental cell types as well as molecules that allow cell growth, cellular adhesion, tissular remodeling, and immune tolerance. Remarkably, some of the cellular processes required for proper placentation are common between placental and cancer cells to finally support tumor growth. Indeed, as in placentation trophoblasts invade and migrate, cancer cells invade and migrate to promote tumor metastasis. However, while these processes respond to a controlled program in trophoblasts, in cancer cells this regulation is lost. Interestingly, it has been shown that autophagy, a process responsible for the degradation of damaged proteins and organelles to maintain cellular homeostasis, is required for invasion of trophoblast cells and for vascular remodeling during placentation. In cancer cells, autophagy has a dual role, as it has been shown both as tumor promoter and inhibitor, depending on the stage and tumor considered. In this review, we summarized the similarities and differences between trophoblast cell invasion and cancer cell metastasis specifically evaluating the role of autophagy in both processes.

Autophagy in the HTR-8/SVneo Cell Oxidative Stress Model Is Associated with the NLRP1 Inflammasome

We investigated whether there was activation of NLRP1 inflammasomes and excessive autophagy in oxidative stress damage. And we further demonstrate whether there is a cascade relationship between the activation of NLRP1 inflammasomes and the phenomenon of excessive autophagy. To observe the expression level of the NLRP1 inflammasome group in the pathological process of trophoblast cell oxidative stress, western blot, immunofluorescence, and qRT-PCR were performed. Autophagy in trophoblast cells after the action of H₂O₂ was detected by using normal trophoblast cells' NLRP1-specific activator (MDP) as a positive control. The presence of excessive autophagy was determined by comparing it with the autophagy-related proteins in normal trophoblast cells. Through siRNA-NLRP1, we investigated the role of oxidative stress and the NLRP1 inflammasome in autophagy in cells. 100 μmol MDP for 24 hours can be used as the optimal concentration of the NLRP1 activator. In human placental trophoblast oxidative stress, the model group significantly increased the expression level of inflammasome IL-1β, CASP1, and NLRP1, compared with the control group NLRP3, and LC3-II, Beclin-1, ATG5, ATG7, and p62 overactivated the autophagy ability of cells. After the activation of NLRP1, the expression of these inflammasomes increased, accompanied by the decrease in autophagy. After the expression of NLRP1 was silenced by RNAi, the expression of inflammasome IL-1β, CASP1, and NLRP3 was also decreased. Still, the autophagy level was increased, which was manifested by the high expression of LC3-II, Beclin-1, ATG5, and ATG7 and the decrease in p62. Trophoblast cells showed the expression of NLRP1 protein and excessive autophagy under oxidative stress. Simultaneously, the NLRP1 inflammasome of trophoblast cells in the state of oxidative stress was correlated with autophagy. Inflammasome activation and autophagy were shown to be linked and to influence each other mutually. These may also provide new therapeutic targets in a pathological pregnancy.

Cell death mechanisms and their roles in pregnancy related disorders

Autophagy and apoptosis are catabolic pathways essential for homeostasis. They play a crucial role for normal placental and fetal development. These cell death mechanisms are exaggerated in placental disorders such as preeclampsia, intrauterine growth restriction (IUGR) and gestational diabetes mellitus (GDM). Apoptosis is widely studied, highly controlled and regulated whereas; autophagy is an orderly degradation and recycling of the cellular components. Cellular senescence may be initiated by a variety of stimuli, including hypoxia, oxidative stress, reduction in survival signals and nutrition deprivation. Apoptosis is regulated by two types of pathways intrinsic and extrinsic. Extrinsic pathway is initiated by apoptosis inducing cells such as macrophages, natural killer cells whereas; intrinsic pathway is initiated in response to DNA damage, cell injury and lack of oxygen. In autophagy, the cell or organelles undergo lysosomal degradation. Placental apoptosis increases as the gestation progresses while autophagy plays a role in trophoblast differentiation and invasion. In pregnancy disorders like preeclampsia and IUGR, proapoptotic markers such as caspase 3, 8, BAX are higher and antiapoptotic markers like Bcl-2 are lower. In GDM, apoptotic markers are reduced resulting in increased placental mass and fetal macrosomia. Apoptosis in the pathological pregnancies is also influenced by the reduced levels of micronutrients and long chain polyunsaturated fatty acids resulting in disturbed placental biology. This chapter describes the role of various key molecular events involved in cellular senescence and the various factors influencing them. This will help identify future therapeutic strategies for better management of these processes.

Evidence for lysosomal biogenesis proteome defect and impaired autophagy in preeclampsia

The etiology of preeclampsia (PE), a serious pregnancy complication, remains an enigma. We have demonstrated that proteinopathy, a pathologic feature of neurodegenerative diseases, is a key observation in the placenta and serum from PE patients. We hypothesize that the macroautophagy/autophagy machinery that mediates degradation of aggregated proteins and damaged organelles is impaired in PE. Here, we show that TFEB (transcription factor EB), a master transcriptional regulator of lysosomal biogenesis, and its regulated proteins, LAMP1, LAMP2, and CTSD (cathepsin D), were dysregulated in the placenta from early and late onset PE deliveries. Primary human trophoblasts and immortalized extravillous trophoblasts (EVTs) showed reduced TFEB expression and nuclear translocation as well as lysosomal protein content in response to hypoxia. Hypoxia-exposed trophoblasts also showed decreased PPP3/calcineurin phosphatase activity and increased XPO1/CRM1 (exportin 1), events that inhibit TFEB nuclear translocation. These proteins were also dysregulated in the PE placenta. These results are supported by observed lysosomal ultrastructural defects with decreased number of autolysosomes in hypoxia-treated primary human trophoblasts. Autophagy-deficient human EVTs exhibited poor TFEB nuclear translocation, reduced lysosomal protein expression and function, and increased MTORC1 activity. Sera from PE patients induced these features and protein aggregation in EVTs. Importantly, trophoblast-specific conditional atg7 knockout mice exhibited reduced TFEB expression with increased deposition of protein aggregates in the placenta. These results provide compelling evidence for a regulatory link between accumulation of protein aggregates and TFEB-mediated impaired lysosomal biogenesis and autophagy in the placenta of PE patients. Abbreviation:atg7: autophagy related 7; CTSD: cathepsin D; ER: endoplasmic reticulum; EVTs: extravillous trophoblasts; KRT7: keratin 7; LAMP1: lysosomal associated membrane protein 1; LAMP2: lysosomal associated membrane protein 2; mSt: mStrawberry; MTORC1: mechanistic target of rapamycin complex 1; NP: normal pregnancy; NPS: normal pregnancy serum; PE: preeclampsia; PES: preeclampsia serum; p-RPS6KB: phosphorylated ribosomal protein S6 kinase B1; SQSTM1/p62: sequestosome 1; TEM: transmission electron microscopy; TFEB: transcription factor EB; XPO1/CRM1: exportin 1.

Autophagy regulates trophoblast invasion by targeting NF-κB activity

Preeclampsia is one of the most serious complications of pregnancy, affecting 5-10% of parturients worldwide. Recent studies have suggested that autophagy is involved in trophoblast invasion and may be associated with defective placentation underlying preeclampsia. We thus aimed to understand the mechanistic link between autophagy and trophoblast invasion. Using the two most commonly used trophoblast cell lines, JEG-3 and HTR-8/SVneo, we inhibited autophagy by ATG5 and beclin-1 shRNA. Conversion of LC3-II was evaluated in ATG5 and beclin-1 knock-down cells in the presence of the lysosomal protease inhibitors E-64d and pepstatin A, to detect the efficiency of autophagy inhibition. Upon autophagy inhibition, we measured cell invasion, activity of NF-κB and related signaling pathways, MMP-2, MMP-9, sFlt-1, and TNF-α levels. Autophagy inhibition increased the invasiveness of these trophoblastic cell lines and increased Akt and NF-κB activity as well as p65 expression. Of note, an NF-κB inhibitor significantly attenuated the trophoblast invasion induced by autophagy inhibition. Autophagy inhibition was also associated with increased MMP-2 and MMP-9 levels and decreased the production of sFlt-1 and TNF-α. Collectively, our results indicate that autophagy regulates trophoblast invasiveness in which the NF-κB pathway and MMP-2, MMP-9, sFlt-1 and TNF-α levels are affected.

Physiological and pathological regulation of autophagy in pregnancy

Autophagy exists widely in eukaryotic cells and is regulated by a variety of molecular mechanisms. Its physiological functions include providing energy, maintaining cell homeostasis, and promoting apoptosis of abnormal cells. At present, the regulation of autophagy in tumor, degenerative disease, and cardiovascular disease has attracted much attention. Gradually, the role of autophagy in pregnancy tends to be valued. The previous literature has shown that autophagy can influence the occurrence and maintenance of pregnancy from three aspects: embryo (affecting the process of fertilization and embryonic development and the function of trophoblast cells), maternal (decidualization), and maternal-to-fetal immune crosstalk. Undoubtedly, abnormalities in autophagy levels are associated with a variety of pregnancy complications, such as preeclampsia, fetal growth restriction, and preterm delivery which have been proven by human, animal, and in vitro experiments. The regulation of autophagy is expected to be a target for the treatment of these pregnancy complications. This article reviews the research on autophagy, especially about its physiological and pathological regulation during pregnancy.

Maternal obesity reduces placental autophagy marker expression in uncomplicated pregnancies

AIM

Obesity has been associated with changes in autophagy and its increasing prevalence among pregnant women is implicated in higher rates of placental-mediated complications of pregnancy such as pre-eclampsia and intrauterine growth restriction. Autophagy is involved in normal placentation, thus changes in autophagy may lead to impaired placental function and development. The aim of this study was to investigate the connection between obesity and autophagy in the placenta in otherwise uncomplicated pregnancies.

METHODS

Immunohistochemistry and western blot analysis were done on placental and omental samples from obese (body mass index [BMI] ≥30 kg/m² ) and normal weight (BMI <25 kg/m² ) pregnant women with singleton pregnancies undergoing planned Caesarean delivery without labor at term. Samples were analyzed for autophagic markers LC3B and p62 in the peripheral, middle and central regions of the placenta and in omental adipocytes, milky spots and vasculature.

RESULTS

As pre-pregnancy BMI increased, there was an increase in both placental and fetal weight as well as decreased levels of LC3B in the central region of the placenta (P = 0.0046). Within the obese patient group, LC3B levels were significantly decreased in the placentas of male fetuses compared to females (P < 0.0001). Adipocytes, compared to milky spots and vasculature, had lower levels of p62 (P = 0.0127) and LC3B (P = 0.003) in obese omenta and lower levels of LC3B in control omenta (P = 0.0071).

CONCLUSION

Obesity leads to reduced placental autophagy in uncomplicated pregnancies; thus, changes in autophagy may be involved in the underlying mechanisms of obesity-related placental diseases of pregnancy.

Disruption of Placental Homeostasis Leads to Preeclampsia

Placental homeostasis is directly linked to fetal well-being and normal fetal growth. Placentas are sensitive to various environmental stressors, including hypoxia, endoplasmic reticulum stress, and oxidative stress. Once placental homeostasis is disrupted, the placenta may rebel against the mother and fetus. Autophagy is an evolutionally conservative mechanism for the maintenance of cellular and organic homeostasis. Evidence suggests that autophagy plays a crucial role throughout pregnancy, including fertilization, placentation, and delivery in human and mouse models. This study reviews the available literature discussing the role of autophagy in preeclampsia.

The autophagy reaction in the human umbilical cord: a potential marker for estimating fetal nutrition and neonatal growth

Objective: To assess the induction of autophagy in the human umbilical cord for physiological adaptation against starvation.Methods: The expression of autophagy-related proteins (LC3-II, p62) in umbilical cord tissues from 40 neonates was assessed by Western blotting. The correlation between the expression of autophagy-related proteins and maternal findings (height, weight, body mass index [BMI]), placental weight, neonatal findings (gestational age, height, weight, Apgar score at 1 min and 5 min), and the pH of the umbilical arterial blood were analyzed using Spearman's rank correlation coefficient test (p values of <.05 were considered significant). Venous blood findings (pH, pCO₂, glucose, total protein, albumin, and lactic acid) were also evaluated in 16 neonates admitted to the NICU.Results: The expression of LC3-II was positively correlated with serum total protein (ρ = 0.564, p = .023). The p62 level was also correlated with maternal BMI (ρ = 0.376, p = .017), the neonatal Apgar score at 1 min (ρ = 0.331 p = .037), total protein (ρ = 0.588, p = .017), and albumin (ρ = 0.552, p = .027) positively. A multiple linear regression analysis that included clinical parameters related to fetal nutrition and neonatal growth revealed that serum total protein was significantly associated with both LC3-II (p = .024) and p62 (p = .034) in the umbilical cord.Conclusion: The LC3-II or p62 expression in the umbilical cord may suggest the autophagy reaction for the homeostasis of protein or amino acid metabolism in the perinatal period.

Endometrial autophagy is essential for embryo implantation during early pregnancy

Embryo implantation is an essential and complex process in mammalian reproduction. However, little evidence has indicated the involvement of autophagy during embryo implantation. To determine the possible role of autophagy in uterine of pregnant mice during the peri-implantation stage, we first examined the expression of autophagy-related markers ATG5 and LC3 on day 4, 5, and 6 of pregnancy (D4, D5, and D6, respectively). Compared with expression on D4, downregulation of the autophagy-related markers was observed on D5 and D6, the days after the embryo attached to the receptivity endometrium. Further examination showed that autophagy-related markers ATG5, ATG12, LC3, cathepsin B, and P62 at the implantation site were significantly decreased when comparing with the inter-implantation site. Fewer number of autophagosomes at the implantation site were also observed by transmission electron microscopy. To confirm the functional role of autophagy during embryo implantation in mice, we administered the autophagy inhibitor 3-methyladenine and chloroquine to mice. After treated with 3-methyladenine, the expression of decidual markers HOXA10 and progesterone receptor were significantly reduced. Furthermore, a reduction in implantation sites and increase in the HOXA10 and PR protein levels were observed in response to chloroquine treatment. In addition, impaired uterine decidualization and dysregulation of the PR and HOXA10 protein levels was observed after autophagy inhibited by 3-methyladenine and chloroquine in in vivo artificial decidualization mouse model. In the last, LC3 and P62 were also observed in normal human proliferative, secretory, and decidua tissues. In conclusion, endometrial autophagy may be essential for embryo implantation, and it may be associated with endometrial decidualization during early pregnancy. KEY MESSAGE: • Autophagy-related markers were significantly decreased at implantation site. • Autophagy inhibition results in abnormal decidualization. • Autophagy is essential for embryo implantation.

Discordant placental oxygenation and autophagy in twin anemia-polycythemia sequence (TAPS)

BACKGROUND

(Macro)autophagy is an important process of self-degradation of macromolecules and organelles that ensures cellular homeostasis and energy preservation during stressful conditions. Dysregulated placental autophagy has been implicated in a wide range of pregnancy complications. Recent studies identified hypoxia as a key regulator of trophoblast autophagy in vitro; however, its effects on placental autophagy in vivo remain incompletely understood. In this study, we evaluated the monochorionic twin anemia-polycythemia sequence (TAPS) placenta as model of discordant placental oxygenation to determine the effects of hypoxia on placental autophagy in utero.

METHODS

We performed a retrospective comparative analysis of tissue oxygenation and autophagy in anemic and polycythemic territories of TAPS placentas (N = 12). Archival tissues were subjected to immunohistochemical, immunofluorescence and Western blot analyses of carbonic anhydrase (CA) IX (hypoxia marker) and key autophagy/lysosomal markers.

RESULTS

CAIX protein levels were significantly higher in anemic twin territories than in corresponding polycythemic territories, consistent with relative tissue hypoxia. Anemic placental shares further displayed significantly higher levels of LC3I/II (autophagosome markers) and LAMP1/2 (lysosome markers), associated with upregulated expression of lysosome/autophagosome activity-associated markers, transcription factor EB and cathepsin D. The accumulation of autophagosomes and lysosomes in anemic shares was accompanied by elevated p62 protein expression, suggestive of inhibition of the downstream autophagy pathway.

CONCLUSIONS

TAPS placentas display striking intertwin discordance in tissue oxygenation and autophagic activity and may provide a suitable model for study of the interrelationship between hypoxia, autophagy, and pregnancy outcome in a monochorionic twin setting.

Maternal serum perlecan levels in women with preeclampsia

Objective: Perlecan is an extracellular matrix proteoglycan suggested to maintain endothelial functions. We aimed to measure maternal serum perlecan levels in different preeclampsia phenotypes.Methods: This study included 50 women with preeclampsia and 30 healthy pregnant women.Results: Serum perlecan levels were significantly higher (p = 0.016) in preeclamptic women with severe features(n = 23) than preeclampsia patients(n = 27). There were no statistically significant differences in serum perlecan levels between the early-onset preeclampsia(n = 25), late-onset preeclampsia(n = 25), and healthy pregnancies.Conclusion: Our findings suggest that preeclamptic women with severe features have higher serum perlecan levels than women with preeclampsia.

Pregnancy-induced hypertension is an independent risk factor for meconium aspiration syndrome: A retrospective population based cohort study

OBJECTIVE

Meconium aspiration syndrome (MAS), possibly resulting from fetal hypoxia, is a respiratory distress disorder in the infant. Pregnancy-induced hypertension (PIH) can cause placental dysfunction and lead to fetal hypoxia, which may induce the development of MAS. Therefore, the aim of this study was to determine the association between PIH and MAS and to identify the predictive risk factors.

MATERIALS AND METHODS

This was a retrospective cohort study. We selected patients with newly diagnosed PIH and a matched cohort group from the Taiwan National Health Insurance Research Database (NHIRD), from January 1, 2000 till December 31, 2013. For each patient in the PIH cohort, 4 subjects without PIH, matched for age and year of delivery, were randomly selected as the comparison cohort. The incidence of meconium aspiration syndrome was assessed in both groups.

RESULTS

Among the 23.3 million individuals registered in the NHIRD, 29,013 patients with PIH and 116,052 matched controls were identified. Patients who experienced PIH had a higher incidence of MAS than did those without PIH. According to a multivariate analysis, PIH (odds ratio [OR] = 1.70, 95% confidence interval [CI] = 1.49-1.93, p < 0.0001) was independently associated with increased risk of MAS. Additionally, age ≥30 years (OR = 1.26, 95% CI = 1.12-1.42, p = 0.0001), nulliparity (OR = 1.13, 95% CI = 1.01-1.27, p = 0.0367) and patients with diabetes mellitus (OR = 3.09, 95% CI = 1.35-7.09, p = 0.0078) were also independent risk factors of MAS.

CONCLUSION

Patients with PIH obtained higher subsequent risk for the development of MAS than those without PIH. Besides, age ≥30 years, nulliparity and patients with diabetes mellitus are the independent risk factors of developing MAS.

Decreased placental apoptosis and autophagy in pregnancies complicated by gestational diabetes with large-for-gestational age fetuses

INTRODUCTION

Dysregulation of placental apoptosis and autophagy are observed in pregnancy complications including preeclampsia and fetal growth restriction. However, studies of their changes in the placentas of women with gestational diabetes mellitus (GDM) show inconsistent results. We aimed to compare the changes in apoptosis, autophagy, and Bcl-2 family proteins in the placentas from women with normal pregnancies and those with GDM, with or without large-for-gestational age (LGA) infants and to investigate the effect of hyperglycemia on the changes in apoptosis, autophagy, and Bcl-2 family proteins in primary cytotrophoblastic cells.

METHODS

Villous tissues were obtained from normal pregnant women and those with GDM, with or without LGA infants. Primary cytotrophoblast cells were isolated from normal term placentas and cultured under standard, hyperglycemic, or hyperosmotic conditions.

RESULTS

Compared to placentas from normal pregnant women, those from GDM women with LGA infants were heavier, had lower beclin-1 and DRAM levels, less M30 and cleaved PARP immunoreactivity, and increased Ki-67 immunoreactivity. These changes were associated with increased Bcl-xL and decreased Bak levels. Increased glucose concentration led to lower ATG5, beclin-1, LC3B-II, p62, and DRAM levels, lower annexin V and M30-positive cell percentages, and less cleaved PARP changes compared with standard culture conditions. Hyperglycemia caused higher Bcl-xL levels and lower Bak and Bad levels than did standard culture conditions.

DISCUSSION

There were differential changes in apoptosis and autophagy between placentas from normal pregnant women and those from GDM women with LGA infants. Bcl-2 family proteins are likely involved in the regulation of these changes.

The fine-tuning of endoplasmic reticulum stress response and autophagy activation during trophoblast syncytialization

The syncytiotrophoblast (STB) is a multinuclear layer forming the outer surface of the fetal part of the placenta deriving from villous cytotrophoblastic cell (vCTB) fusion and differentiation. This syncytialization process is characterized by morphological and biochemical alterations of the trophoblast, which probably require removal of pre-existing structures and proteins to maintain cell homeostasis and survival. Interestingly, autophagy, which allows degradation and recycling of cellular components, was shown to be activated in syncytiotrophoblast. Here we examined the involvement of endoplasmic reticulum stress (ERS) response in autophagy activation during vCTB syncytialization. We first demonstrated the activation of ERS response and autophagy during the time course of trophoblastic cell fusion and differentiation. Alteration of autophagy activation in vCTB by chemical treatments or Beclin-1 expression modulation leads to a decrease in trophoblastic syncytialization. Furthermore, ERS response inhibition by chemical treatment or siRNA strategy leads to a default in syncytialization, associated with alteration of autophagy markers and cell survival. From these data, we suggest that ERS response, by fine regulation of autophagy activation, may serve as an adaptive mechanism to promote cell survival during trophoblastic syncytialization.

Current Understanding of Autophagy in Pregnancy

Autophagy is an evolutionarily conserved process in eukaryotes to maintain cellular homeostasis under environmental stress. Intracellular control is exerted to produce energy or maintain intracellular protein quality controls. Autophagy plays an important role in embryogenesis, implantation, and maintenance of pregnancy. This role includes supporting extravillous trophoblasts (EVTs) that invade the decidua (endometrium) until the first third of uterine myometrium and migrate along the lumina of spiral arterioles under hypoxic and low-nutrient conditions in early pregnancy. In addition, autophagy inhibition has been linked to poor placentation—a feature of preeclamptic placentas—in a placenta-specific autophagy knockout mouse model. Studies of autophagy in human placentas have revealed controversial results, especially with regard to preeclampsia and gestational diabetes mellitus (GDM). Without precise estimation of autophagy flux, wrong interpretation would lead to fixed tissues. This paper presents a review of the role of autophagy in pregnancy and elaborates on the interpretation of autophagy in human placental tissues.

Melatonin modulates autophagy and inflammation protecting human placental trophoblast from hypoxia/reoxygenation

Melatonin has been proposed as a possible treatment for the deleterious effects of hypoxia/reoxygenation (H/R), such as autophagy, inflammation, and apoptosis. Pathological pregnancies, such as preeclampsia, are associated with placental H/R, and decreased placental melatonin synthesis as well as lower melatonin levels in the placenta and maternal plasma. However, the effects of exogenous melatonin on inflammation and autophagy induced by pregnancy complications associated with H/R await investigation. This study aimed to determine as to whether melatonin protects human primary villous trophoblasts against H/R-induced autophagy, inflammation, and apoptosis. Human primary villous cytotrophoblasts were isolated and immunopurified from normal term placentas. These cells were then exposed or not to 1 mmol/L melatonin for 72 hour in normoxia (8% O₂ ), thereby inducing differentiation into syncytiotrophoblast that was then exposed to H/R (0.5% O₂ , for 4 hour) or normoxia. H/R decreased endogenous melatonin synthesis (by 68%) and interleukin (IL)-10 levels (by 72%), coupled to increased tumor necrosis factor (TNF) (by 114%), IL-6 (by 55%), and NFκB (by 399%), compared to normoxia. Melatonin treatment reversed the H/R effect, restoring IL-10, TNF, and IL-6 levels to those of the normoxia condition. Melatonin, as well as NFκB inhibition, enhanced autophagy activation, consequently increasing syncytiotrophoblast survival in H/R conditions. This study suggests that H/R, which is present in pregnancy complications, inhibits endogenous melatonin production, thereby contributing to reduced syncytiotrophoblast viability. Results indicate that exogenous melatonin treatment may afford protection against H/R-induced damage, thereby enhancing placental cell survival, and contributing to improved fetal outcomes.

Linc02527 promoted autophagy in Intrahepatic cholestasis of pregnancy

LncRNA plays a crucial role in human disease. However, the expression and function of LncRNA in ICP(Intrahepatic cholestasis of pregnancy) is still not fully elucidated. In this study, we found Linc02527 was increased expression in placenta and serum of ICP patients. Ectopically expression of Linc02527 promoted autophagy and proliferate in HTR8 cells. Silencing Linc02527 suppressed the autophagy and proliferate in HTR8 cells. Mechanically study revealed that Linc02527 regulated the expression of ATG5 and ATG7 by sponging miR-3185. Linc02527 directly binding to YBX1 and activated P21. The growth of C57 mouse was retarded when autophagy was activated. In normal condition, inhibited autophagy using chloroquine did not affect the growth of C57 mouse. However, in the condition of autophagy was activated, inhibited autophagy using chloroquine can improve the growth of C57 mouse. Overall, the results of this study identified Linc02527 as a candidate biomarker in ICP and a potential target for ICP therapy. Chloroquine was a potential drug for ICP therapy.

Expression of urotensin II is associated with placental autophagy in patients with severe preeclampsia

The aims of this study are to explore the correlation between the expressions of urotensin II (UII) and autophagic markers (LC3 and P62) in patients with severe preeclampsia (SPE). A total of 64 pregnant subjects were recruited, including 29 healthy pregnancies and 35 preeclamptic patients (7 mild preeclamptic (MPE) patients and 28 SPE patients). UII and autophagic markers expression in placenta specimens was investigated by immunohistochemistry (IHC), RT-qPCR, and western blot. IHC analysis manifested that the expressions of UII and autophagic markers were mainly located in the placental cytotrophoblast and syncytiotrophoblast. Western blot and IHC analysis both indicated that the expression of UII was significantly correlated with autophagic marker LC3II (by western blot) or LC3 (by IHC) (r = 0.495, P = 0.010; r = 0.816, P = 0.007). Moreover, SPE group had higher expression of UII and LC3II, lower expression of P62 than that of normal controls. The expression of LC3II was positively related with systolic blood pressure (SBP) and urinary protein level (SBP (r = 0.501, P = 0.003) and urine protein quantitation (r = 0.509, P = 0.022)), whereas P62 had negative correlation with SBP. We first verify that UII has positive correlation with autophagic marker LC3 in placentas of preeclampsia patients; besides, autophagic levels are positively correlated with SBP and urine protein in patients with SPE.

Downregulation of p53 drives autophagy during human trophoblast differentiation

The placental barrier is crucial for the supply of nutrients and oxygen to the developing fetus and is maintained by differentiation and fusion of mononucleated cytotrophoblasts into the syncytiotrophoblast, a process only partially understood. Here transcriptome and pathway analyses during differentiation and fusion of cultured trophoblasts yielded p53 signaling as negative upstream regulator and indicated an upregulation of autophagy-related genes. We further showed p53 mRNA and protein levels decreased during trophoblast differentiation. Reciprocally, autophagic flux increased and cytoplasmic LC3B-GFP puncta became more abundant, indicating enhanced autophagic activity. In line, in human first trimester placenta p53 protein mainly localized to the cytotrophoblast, while autophagy marker LC3B as well as late autophagic compartments were predominantly detectable in the syncytiotrophoblast. Importantly, ectopic overexpression of p53 reduced levels of LC3B-II, supporting a negative regulatory role on autophagy in differentiating trophoblasts. This was also shown in primary trophoblasts and human first trimester placental explants, where pharmacological stabilization of p53 decreased LC3B-II levels. In summary our data suggest that differentiation-dependent downregulation of p53 is a prerequisite for activating autophagy in the syncytiotrophoblast.

Overexpression of long non-coding RNA H19 promotes invasion and autophagy via the PI3K/AKT/mTOR pathways in trophoblast cells

BACKGROUND

Preeclampsia (PE), characterized by hypertension and proteinuria, is a leading cause of perinatal and maternal mortality. Considering that mutation of H19 gene is closely associated with PE, we aimed to explore the functional role of long non-coding RNA H19 (lncRNA-H19) in trophoblast cells.

METHODS

Expression of lncRNA-H19 in placenta tissues from patients with PE and healthy pregnant women after delivery was determined by quantitative reverse transcription PCR. Then, lncRNA-H19 was abnormally expressed in JEG-3 and HTR-8 cells by stable cell transfection. Cell viability and invasion were assessed by using CCK-8 and Matrigel-coated Millicell system, respectively. Expression of key proteins associated with invasion and autophagy as well as key kinases in the phosphatidylinositol-3-kinase (PI3K)/AKT/mechanistic target of rapamycin (mTOR) pathways were measured by Western blot analysis. Number of GFP-labeled autophagosomes was counted under a confocal microscope.

RESULTS

Level of lncRNA-H19 in the placenta tissues from PE patients was higher than that from healthy controls. LncRNA-H19 overexpression reduced cell viability but increased invasion of JEG-3 and HTR-8 cells. LncRNA-H19 silence showed the opposite effects. In addition, lncRNA-H19 overexpression promoted autophagy in trophoblast cells. Furthermore, phosphorylated levels of key kinases in the PI3K/AKT/mTOR pathways were enhanced by lncRNA-H19 overexpression while were reduced by lncRNA-H19 silence.

CONCLUSION

LncRNA-H19, which was up-regulated in PE, reduced cell viability but promoted invasion and autophagy in trophoblast cells, along with activation of the PI3K/AKT/mTOR pathways. Our study provides a theoretical basis for pathogenesis of PE, aiding to identification of novel therapeutic strategies for PE.

Abnormal CYP11A1 gene expression induces excessive autophagy, contributing to the pathogenesis of preeclampsia

Objective

In this study, we investigated the exact mechanism by which excessive CYP11A1 expression impairs the placentation process and whether this causes preeclampsia (PE) in an in vivo model.

Setting and Design

In order to study CYP11A1 overexpression, BeWo cells were transfected with CYP11A1. Pregnenolone, progesterone, and testosterone levels were measured by enzyme linked immunosorbent assays, and levels of autophagy markers were quantified by western blotting and immunofluorescence. Trophoblastic cell invasion was assessed using transwell assays; BeWo cells were treated with testosterone and an androgen receptor (AR) inhibitor (flutamide) to elucidate the invasion mechanism. An adenovirus overexpression rat model was established to investigate CYP11A1 overexpression in vivo and the phenotype was examined. Furthermore, human placenta samples (n = 24) were used to determine whether PE patient placentas showed altered CYP11A1 and autophagy marker expression.

Results

BeWo cells overexpressing CYP11A1 had significantly increased levels of pregnenolone, progesterone, and testosterone. Additionally, the expression levels of autophagy markers in CYP11A1-overexpressing BeWo cells were significantly increased. Trophoblast invasion was significantly reduced in CYP11A1-overexpressing cells as well as in cells treated with high testosterone. This reduction could be significantly rescued when cells were pretreated with flutamide. Overexpression of CYP11A1 in rat pregnancies led to PE-like symptoms and an over-activation of the AR-mediated pathway in the placenta. Elevated expression of CYP11A1 and autophagy markers could also be detected in PE placenta samples.

Conclusions

These results suggest that abnormally high expression of CYP11A1 induces trophoblast autophagy and inhibits trophoblastic invasion, which is associated with the etiology of PE.

Endoplasmic reticulum stress responses in placentation - A true balancing act

The unfolded protein response (UPR) is recognized as a key mechanism to promote protein folding and processing in eukaryotes when endoplasmic reticulum stress (ERS) occurs. Some conditions such as hypoxia or glucose deprivation are factors that may elicit ERS response. Recent literature collectively proposes that ERS response is crucial for mammalian reproduction by allowing decidualization and placentation to occur. However, prolonged ERS and activation of UPR pathways can lead to apoptosis and autophagy, which in turn could pose adverse effects on pregnancy outcomes and placentation. ERS associated pregnancy pathologies include intrauterine growth restriction and early-onset preeclampsia. Given these findings, evidence suggests that overactivation of UPR may lead to harmful reproductive circumstances, whereas physiological regulation of ERS response is essential for mammalian reproduction and placental function. In this review, we discuss the dual role of UPR activation with respect to its contribution to placental development as well as pathologies caused by pathway overactivation. In addition, we suggest potential protein markers associated with the UPR, as circulating C-terminal GRP78 or anti-GRP78 autoantibodies which may prove to be of clinical interest.

Autophagy in the placenta

Autophagy is an evolutionarily conserved catalytic process by which cytoplasmic components including damaged macromolecules and organelles are degraded. The role of autophagy includes adaptive responses to nutrition deprivation or intracellular stimuli. Although autophagosomes were first observed in early 1960s, it was 1990s that autophagy-related genes in yeast were identified and studied. Nowadays, the molecular machinery of autophagy and signaling pathway to various stimuli are almost outlined. Dysregulation of autophagic activity has been implicated in many human diseases including neurodegenerative diseases, infection and inflammation, and malignancies. However, since current understanding of autophagy in placenta is just at the beginning, this paper aims to provide general information on autophagy (part I) and to summarize articles on autophagy in human placenta (part II). This review article will serve as a basis for further researches on autophagy in relation to human pregnancy and its complications.