Lipid nanoparticle structure and delivery route during pregnancy dictate mRNA potency, immunogenicity, and maternal and fetal outcomes

Treating pregnancy-related disorders is exceptionally challenging because the threat of maternal and/or fetal toxicity discourages the use of existing medications and hinders new drug development. One potential solution is the use of lipid nanoparticle (LNP) RNA therapies, given their proven efficacy, tolerability, and lack of fetal accumulation. Here, we describe LNPs for efficacious mRNA delivery to maternal organs in pregnant mice via several routes of administration. In the placenta, our lead LNP transfected trophoblasts, endothelial cells, and immune cells, with efficacy being structurally dependent on the ionizable lipid polyamine headgroup. Next, we show that LNP-induced maternal inflammatory responses affect mRNA expression in the maternal compartment and hinder neonatal development. Specifically, pro-inflammatory LNP structures and routes of administration curtailed efficacy in maternal lymphoid organs in an IL-1β-dependent manner. Further, immunogenic LNPs provoked the infiltration of adaptive immune cells into the placenta and restricted pup growth after birth. Together, our results provide mechanism-based structural guidance on the design of potent LNPs for safe use during pregnancy.

Strikingly High Activity of 15-Lipoxygenase Towards Di-Polyunsaturated Arachidonoyl/Adrenoyl-Phosphatidylethanolamines Generates Peroxidation Signals of Ferroptotic Cell Death

The vast majority of membrane phospholipids (PLs) include two asymmetrically positioned fatty acyls: oxidizable polyunsaturated fatty acids (PUFA) attached predominantly at the sn2 position, and non-oxidizable saturated/monounsaturated acids (SFA/MUFA) localized at the sn1 position. The peroxidation of PUFA-PLs, particularly sn2-arachidonoyl(AA)- and sn2-adrenoyl(AdA)-containing phosphatidylethanolamines (PE), has been associated with the execution of ferroptosis, a program of regulated cell death. There is a minor subpopulation (≈1-2 mol %) of doubly PUFA-acylated phospholipids (di-PUFA-PLs) whose role in ferroptosis remains enigmatic. Here we report that 15-lipoxygenase (15LOX) exhibits unexpectedly high pro-ferroptotic peroxidation activity towards di-PUFA-PEs. We revealed that peroxidation of several molecular species of di-PUFA-PEs occurred early in ferroptosis. Ferrostatin-1, a typical ferroptosis inhibitor, effectively prevented peroxidation of di-PUFA-PEs. Furthermore, co-incubation of cells with di-AA-PE and 15LOX produced PUFA-PE peroxidation and induced ferroptotic death. The decreased contents of di-PUFA-PEs in ACSL4 KO A375 cells was associated with lower levels of di-PUFA-PE peroxidation and enhanced resistance to ferroptosis. Thus, di-PUFA-PE species are newly identified phospholipid peroxidation substrates and regulators of ferroptosis, representing a promising therapeutic target for many diseases related to ferroptotic death.

High-yield and rapid isolation of extracellular vesicles by flocculation via orbital acoustic trapping: FLOAT

Extracellular vesicles (EVs) have been identified as promising biomarkers for the noninvasive diagnosis of various diseases. However, challenges in separating EVs from soluble proteins have resulted in variable EV recovery rates and low purities. Here, we report a high-yield ( > 90%) and rapid ( < 10 min) EV isolation method called FLocculation via Orbital Acoustic Trapping (FLOAT). The FLOAT approach utilizes an acoustofluidic droplet centrifuge to rotate and controllably heat liquid droplets. By adding a thermoresponsive polymer flocculant, nanoparticles as small as 20 nm can be rapidly and selectively concentrated at the center of the droplet. We demonstrate the ability of FLOAT to separate urinary EVs from the highly abundant Tamm-Horsfall protein, addressing a significant obstacle in the development of EV-based liquid biopsies. Due to its high-yield nature, FLOAT reduces biofluid starting volume requirements by a factor of 100 (from 20 mL to 200 µL), demonstrating its promising potential in point-of-care diagnostics.

The impact of opioids on the transcriptional landscape of human villous trophoblasts

INTRODUCTION

Opioid use disorder (OUD) is implicated in major obstetrical diseases such as fetal growth restriction. Whether or not opioids directly impact placental trophoblast development and function remains unclear. We sought to examine the expression of opioid receptors (OPRs) in villous trophoblasts and the effect of opioids on placental transcriptomics.

METHODS

Trophoblast stem (TS) cells and primary human trophoblast (PHT) cells from healthy term placentas were used to assess OPR expression in conditions that enhance trophoblast stemness vs differentiation. Placental RNAseq was conducted using our retrospective cohorts of pregnant people with OUD vs controls, both without major obstetrical complications. RT-qPCR was used to determine the effect of fentanyl on the expression of putative opioid targets and stemness or differentiation-associated genes in TS and PHT cells.

RESULTS

Three main OPRs, including OPRM1, OPRD1, and OPRK1 were expressed in term PHT cells cultured in the stemness medium, whereas only OPRD1 and OPRK1 were expressed in TS cells. Interestingly, upon induction of differentiation, the expressed OPR mRNAs in TS or in PHT cells were downregulated. We found 286 differentially expressed long RNAs in placentas from the OUD participants vs controls. While three putative opioid targets differed their expression in stemness vs differentiation states of trophoblasts, fentanyl had no effect on their expression or the expression of major stemness or differentiation-relevant genes in TS and PHT cells.

DISCUSSION

Trophoblastic expression of OPRs and opioid RNA targets is impacted by cell differentiation, suggesting differential susceptibility of villous trophoblasts to the effect of opioids.

Defining trophoblast injury patterns in the transcriptomes of dysfunctional placentas

Trophoblast injury is central to clinically relevant placenta dysfunction. We hypothesized that the mRNA of primary human trophoblasts, exposed to distinct injuries in vitro, capture transcriptome patterns of placental biopsies obtained from common obstetrical syndromes. We deployed a CIBERSORTx deconvolution method to correlate trophoblastic RNAseq-based expression matrices with the transcriptome of omics-defined placental dysfunction patterns in vivo. We found distinct trophoblast injury patterns in placental biopsies from women with fetal growth restriction and a hypertensive disorder, or in biopsies clustered by their omics analysis. Our RNAseq data are useful for defining the contribution of trophoblast injuries to placental dysfunction syndromes.

Integrated unbiased multiomics defines disease-independent placental clusters in common obstetrical syndromes

BACKGROUND

Placental dysfunction, a root cause of common syndromes affecting human pregnancy, such as preeclampsia (PE), fetal growth restriction (FGR), and spontaneous preterm delivery (sPTD), remains poorly defined. These common, yet clinically disparate obstetrical syndromes share similar placental histopathologic patterns, while individuals within each syndrome present distinct molecular changes, challenging our understanding and hindering our ability to prevent and treat these syndromes.

METHODS

Using our extensive biobank, we identified women with severe PE (n = 75), FGR (n = 40), FGR with a hypertensive disorder (FGR + HDP; n = 33), sPTD (n = 72), and two uncomplicated control groups, term (n = 113), and preterm without PE, FGR, or sPTD (n = 16). We used placental biopsies for transcriptomics, proteomics, metabolomics data, and histological evaluation. After conventional pairwise comparison, we deployed an unbiased, AI-based similarity network fusion (SNF) to integrate the datatypes and identify omics-defined placental clusters. We used Bayesian model selection to compare the association between the histopathological features and disease conditions vs SNF clusters.

RESULTS

Pairwise, disease-based comparisons exhibited relatively few differences, likely reflecting the heterogeneity of the clinical syndromes. Therefore, we deployed the unbiased, omics-based SNF method. Our analysis resulted in four distinct clusters, which were mostly dominated by a specific syndrome. Notably, the cluster dominated by early-onset PE exhibited strong placental dysfunction patterns, with weaker injury patterns in the cluster dominated by sPTD. The SNF-defined clusters exhibited better correlation with the histopathology than the predefined disease groups.

CONCLUSIONS

Our results demonstrate that integrated omics-based SNF distinctively reclassifies placental dysfunction patterns underlying the common obstetrical syndromes, improves our understanding of the pathological processes, and could promote a search for more personalized interventions.

The lipase cofactor CGI58 controls placental lipolysis

In eutherians, the placenta plays a critical role in the uptake, storage, and metabolism of lipids. These processes govern the availability of fatty acids to the developing fetus, where inadequate supply has been associated with substandard fetal growth. Whereas lipid droplets are essential for the storage of neutral lipids in the placenta and many other tissues, the processes that regulate placental lipid droplet lipolysis remain largely unknown. To assess the role of triglyceride lipases and their cofactors in determining placental lipid droplet and lipid accumulation, we assessed the role of patatin like phospholipase domain containing 2 (PNPLA2) and comparative gene identification-58 (CGI58) in lipid droplet dynamics in the human and mouse placenta. While both proteins are expressed in the placenta, the absence of CGI58, not PNPLA2, markedly increased placental lipid and lipid droplet accumulation. These changes were reversed upon restoration of CGI58 levels selectively in the CGI58-deficient mouse placenta. Using co-immunoprecipitation, we found that, in addition to PNPLA2, PNPLA9 interacts with CGI58. PNPLA9 was dispensable for lipolysis in the mouse placenta yet contributed to lipolysis in human placental trophoblasts. Our findings establish a crucial role for CGI58 in placental lipid droplet dynamics and, by extension, in nutrient supply to the developing fetus.

A solution to the biophysical fractionation of extracellular vesicles: Acoustic Nanoscale Separation via Wave-pillar Excitation Resonance (ANSWER)

High-precision isolation of small extracellular vesicles (sEVs) from biofluids is essential toward developing next-generation liquid biopsies and regenerative therapies. However, current methods of sEV separation require specialized equipment and time-consuming protocols and have difficulties producing highly pure subpopulations of sEVs. Here, we present Acoustic Nanoscale Separation via Wave-pillar Excitation Resonance (ANSWER), which allows single-step, rapid (<10 min), high-purity (>96% small exosomes, >80% exomeres) fractionation of sEV subpopulations from biofluids without the need for any sample preprocessing. Particles are iteratively deflected in a size-selective manner via an excitation resonance. This previously unidentified phenomenon generates patterns of virtual, tunable, pillar-like acoustic field in a fluid using surface acoustic waves. Highly precise sEV fractionation without the need for sample preprocessing or complex nanofabrication methods has been demonstrated using ANSWER, showing potential as a powerful tool that will enable more in-depth studies into the complexity, heterogeneity, and functionality of sEV subpopulations.

Extracellular vesicles and immune response during pregnancy: A balancing act

The mechanisms underlying maternal tolerance of the semi- or fully-allogeneic fetus are intensely investigated. Across gestation, feto-placental antigens interact with the maternal immune system locally within the trophoblast-decidual interface and distantly through shed cells and soluble molecules that interact with maternal secondary lymphoid tissues. The discovery of extracellular vesicles (EVs) as local or systemic carriers of antigens and immune-regulatory molecules has added a new dimension to our understanding of immune modulation prior to implantation, during trophoblast invasion, and throughout the course of pregnancy. New data on immune-regulatory molecules, located on EVs or within their cargo, suggest a role for EVs in negotiating immune tolerance during gestation. Lessons from the field of transplant immunology also shed light on possible interactions between feto-placentally derived EVs and maternal lymphoid tissues. These insights illuminate a potential role for EVs in major obstetrical disorders. This review provides updated information on intensely studied, pregnancy-related EVs, their cargo molecules, and patterns of fetal-placental-maternal trafficking, highlighting potential immune pathways that might underlie immune suppression or activation in gestational health and disease. Our summary also underscores the likely need to broaden the definition of the maternal-fetal interface to systemic maternal immune tissues that might interact with circulating EVs.

Placental miRNAs Targeting Cellular Stress Response Pathways Are Highly Expressed in Non-Hispanic Black People

Non-Hispanic Black (NHB) people have a 2.5-fold higher risk of maternal mortality when compared to non-Hispanic White (NHW) people. Neonates of NHB people are more likely to be born preterm and small for gestational age, which may be driven by structural racism. The placenta is very sensitive to the maternal environment and may play a critical role in the translation of environmental stressors to pregnancy outcomes. Our aim was to assess the placental miRNA expression profile in both NHB and NHW people and the association between differentially expressed miRNAs and pregnancy outcomes. Placentas were collected from 50 NHB and 74 NHW people with a normal singleton pregnancy undergoing elective cesarean section at term prior to the onset of labor. Placental miRNA expression was measured via whole-genome small RNA-sequencing in a subset of 77 placentas. Fifteen miRNAs were more highly expressed in the placentas of NHB people. Several of these miRNAs were associated with cellular stress response pathways, suggesting that they may be responding to environmental stressors. Placental miR-192-5p expression was lower among NHB people and was positively associated with neonatal adiposity, suggesting it may be sensitive to structural racism with potential impacts on fetal growth.

Placental miR-3940-3p Is Associated With Maternal Insulin Resistance in Late Pregnancy

CONTEXT

An increase in maternal insulin resistance (IR) during pregnancy is essential for normal fetal growth. The mechanisms underlying this adaptation are poorly understood. Placental factors are believed to instigate and maintain these changes, as IR decreases shortly after delivery. Methylation of placental gene loci that are common targets for miRNAs are associated with maternal IR.

OBJECTIVE

We hypothesized that placental miRNAs targeting methylated loci are associated with maternal IR during late pregnancy.

METHODS

We collected placentas from 132 elective cesarean sections and fasting blood samples at delivery to estimate maternal homeostasis model assessment of insulin resistance (HOMA-IR). Placental miRNA expression was measured via whole genome small-RNA sequencing in a subset of 40 placentas selected by maternal pre-gravid body mass index (BMI) and neonatal adiposity. Five miRNAs correlated with maternal HOMA-IR and previously identified as targeting methylated genes were selected for validation in all 132 placenta samples via RT-qPCR. Multiple regression adjusted for relevant clinical variables.

RESULTS

Median maternal age was 27.5 years, with median pre-pregnancy BMI of 24.7 kg/m2, and median HOMA-IR of 2.9. Among the 5 selected miRNA, maternal HOMA-IR correlated with the placental expression of miRNA-371b-3p (r = 0.25; P = 0.008) and miRNA-3940-3p (r = 0.32; P = 0.0004) across the 132 individuals. After adjustment for confounding variables, placental miRNA-3940-3p expression remained significantly associated with HOMA-IR (β = 0.16; P = 0.03).

CONCLUSION

Placental miRNA-3940-3p was associated with maternal IR at delivery. This placental miRNA may have an autocrine or paracrine effect-regulating placental genes involved in modulating maternal IR.

Placental response to maternal SARS-CoV-2 infection

The coronavirus disease 2019 (COVID-19) pandemic affected people at all ages. Whereas pregnant women seemed to have a worse course of disease than age-matched non-pregnant women, the risk of feto-placental infection is low. Using a cohort of 66 COVID-19-positive women in late pregnancy, we correlated clinical parameters with disease severity, placental histopathology, and the expression of viral entry and Interferon-induced transmembrane (IFITM) antiviral transcripts. All newborns were negative for SARS-CoV-2. None of the demographic parameters or placental histopathological characteristics were associated with disease severity. The fetal-maternal transfer ratio for IgG against the N or S viral proteins was commonly less than one, as recently reported. We found that the expression level of placental ACE2, but not TMPRSS2 or Furin, was higher in women with severe COVID-19. Placental expression of IFITM1 and IFITM3, which have been implicated in antiviral response, was higher in participants with severe disease. We also showed that IFITM3 protein expression, which localized to early and late endosomes, was enhanced in severe COVID-19. Our data suggest an association between disease severity and placental SARS-CoV-2 processing and antiviral pathways, implying a role for these proteins in placental response to SARS-CoV-2.

RNA Network Interactions During Differentiation of Human Trophoblasts

In the human placenta, two trophoblast cell layers separate the maternal blood from the villous basement membrane and fetal capillary endothelial cells. The inner layer, which is complete early in pregnancy and later becomes discontinuous, comprises the proliferative mononuclear cytotrophoblasts, which fuse together and differentiate to form the outer layer of multinucleated syncytiotrophoblasts. Because the syncytiotrophoblasts are responsible for key maternal-fetal exchange functions, tight regulation of this differentiation process is critical for the proper development and the functional role of the placenta. The molecular mechanisms regulating the fusion and differentiation of trophoblasts during human pregnancy remain poorly understood. To decipher the interactions of non-coding RNAs (ncRNAs) in this process, we exposed cultured primary human trophoblasts to standard in vitro differentiation conditions or to conditions known to hinder this differentiation process, namely exposure to hypoxia (O₂ < 1%) or to the addition of dimethyl sulfoxide (DMSO, 1.5%) to the culture medium. Using next generation sequencing technology, we analyzed the differential expression of trophoblastic lncRNAs, miRNAs, and mRNAs that are concordantly modulated by both hypoxia and DMSO. Additionally, we developed a model to construct a lncRNA-miRNA-mRNA co-expression network and inferred the functions of lncRNAs and miRNAs via indirect gene ontology analysis. This study improves our knowledge of the interactions between ncRNAs and mRNAs during trophoblast differentiation and identifies key biological processes that may be impaired in common gestational diseases, such as fetal growth restriction or preeclampsia.

Ferroptosis induces membrane blebbing in placental trophoblasts

Ferroptosis is a regulated, non-apoptotic form of cell death, characterized by hydroxy-peroxidation of discrete phospholipid hydroperoxides, particularly hydroperoxyl (Hp) forms of arachidonoyl- and adrenoyl-phosphatidylethanolamine, with a downstream cascade of oxidative damage to membrane lipids, proteins and DNA, culminating in cell death. We recently showed that human trophoblasts are particularly sensitive to ferroptosis caused by depletion or inhibition of glutathione peroxidase 4 (GPX4) or the lipase PLA2G6. Here, we show that trophoblastic ferroptosis is accompanied by a dramatic change in the trophoblast plasma membrane, with macro-blebbing and vesiculation. Immunofluorescence revealed that ferroptotic cell-derived blebs stained positive for F-actin, but negative for cytoplasmic organelle markers. Transfer of conditioned medium that contained detached macrovesicles or co-culture of wild-type target cells with blebbing cells did not stimulate ferroptosis in target cells. Molecular modeling showed that the presence of Hp-phosphatidylethanolamine in the cell membrane promoted its cell ability to be stretched. Together, our data establish that membrane macro-blebbing is characteristic of trophoblast ferroptosis and can serve as a useful marker of this process. Whether or not these blebs are physiologically functional remains to be established.

Curvature-Regulated Lipid Membrane Softening of Nano-Vesicles

The physico-mechanical properties of nanoscale lipid vesicles (e.g., natural nano-vesicles and artificial nano-liposomes) dictate their interaction with biological systems. Understanding the interplay between vesicle size and stiffness is critical to both the understanding of the biological functions of natural nano-vesicles and the optimization of nano-vesicle-based diagnostics and therapeutics. It has been predicted that, when vesicle size is comparable to its membrane thickness, the effective bending stiffness of the vesicle increases dramatically due to both the entropic effect as a result of reduced thermal undulation and the nonlinear curvature elasticity effect. Through systematic molecular dynamics simulations, we show that the vesicle membrane thins and softens with the decrease in vesicle size, which effectively counteracts the stiffening effects as already mentioned. Our simulations indicate that the softening of nano-vesicles results from a change in the bilayer's interior structure - a decrease in lipid packing order - as the membrane curvature increases. Our work thus leads to a more complete physical framework to understand the physico-mechanical properties of nanoscale lipid vesicles, paving the way to further advances in the biophysics of nano-vesicles and their biomedical applications.

Trophoblastic extracellular vesicles and viruses: Friends or foes?

Cells produce cytoplasmic vesicles to facilitate the processing and transport of RNAs, proteins, and other signaling molecules among intracellular organelles. Moreover, most cells release a range of extracellular vesicles (EVs) that mediate intercellular communication in both physiological and pathological settings. In addition to a better understanding of their biological functions, the diagnostic and therapeutic prospects of EVs, particularly the nano-sized small EVs (sEVs, exosomes), are currently being rigorously pursued. While EVs and viruses such as retroviruses might have evolved independently, they share a number of similar characteristics, including biogenesis pathways, size distribution, cargo, and cell-targeting mechanisms. The interplay of EVs with viruses has profound effects on viral replication and infectivity. Our research indicates that sEVs, produced by primary human trophoblasts, can endow other non-placental cell types with antiviral response. Better insights into the interaction of EVs with viruses may illuminate new ways to attenuate viral infections during pregnancy, and perhaps develop new antiviral therapeutics to protect the feto-placental unit during critical times of human development.

Deep phenotyping during pregnancy for predictive and preventive medicine

Deep phenotyping during pregnancy offers an opportunity to define the antecedents of lifelong health and wellness, and to improve pregnancy outcomes.

Extracellular vesicles promote transkingdom nutrient transfer during viral-bacterial co-infection

Extracellular vesicles (EVs) are increasingly appreciated as a mechanism of communication among cells that contribute to many physiological processes. Although EVs can promote either antiviral or proviral effects during viral infections, the role of EVs in virus-associated polymicrobial infections remains poorly defined. We report that EVs secreted from airway epithelial cells during respiratory viral infection promote secondary bacterial growth, including biofilm biogenesis, by Pseudomonas aeruginosa. Respiratory syncytial virus (RSV) increases the release of the host iron-binding protein transferrin on the extravesicular face of EVs, which interact with P. aeruginosa biofilms to transfer the nutrient iron and promote bacterial biofilm growth. Vesicular delivery of iron by transferrin more efficiently promotes P. aeruginosa biofilm growth than soluble holo-transferrin delivered alone. Our findings indicate that EVs are a nutrient source for secondary bacterial infections in the airways during viral infection and offer evidence of transkingdom communication in the setting of polymicrobial infections.

Acoustofluidic centrifuge for nanoparticle enrichment and separation

Liquid droplets have been studied for decades and have recently experienced renewed attention as a simplified model for numerous fascinating physical phenomena occurring on size scales from the cell nucleus to stellar black holes. Here, we present an acoustofluidic centrifugation technique that leverages an entanglement of acoustic wave actuation and the spin of a fluidic droplet to enable nanoparticle enrichment and separation. By combining acoustic streaming and droplet spinning, rapid (<1 min) nanoparticle concentration and size-based separation are achieved with a resolution sufficient to identify and isolate exosome subpopulations. The underlying physical mechanisms have been characterized both numerically and experimentally, and the ability to process biological samples (including DNA segments and exosome subpopulations) has been successfully demonstrated. Together, this acoustofluidic centrifuge overcomes existing limitations in the manipulation of nanoscale (<100 nm) bioparticles and can be valuable for various applications in the fields of biology, chemistry, engineering, material science, and medicine.

Resolving the paradox of ferroptotic cell death: Ferrostatin-1 binds to 15LOX/PEBP1 complex, suppresses generation of peroxidized ETE-PE, and protects against ferroptosis

Hydroperoxy-eicosatetraenoyl-phosphatidylethanolamine (HpETE-PE) is a ferroptotic cell death signal. HpETE-PE is produced by the 15-Lipoxygenase (15LOX)/Phosphatidylethanolamine Binding Protein-1 (PEBP1) complex or via an Fe-catalyzed non-enzymatic radical reaction. Ferrostatin-1 (Fer-1), a common ferroptosis inhibitor, is a lipophilic radical scavenger but a poor 15LOX inhibitor arguing against 15LOX having a role in ferroptosis. In the current work, we demonstrate that Fer-1 does not affect 15LOX alone, however, it effectively inhibits HpETE-PE production by the 15LOX/PEBP1 complex. Computational molecular modeling shows that Fer-1 binds to the 15LOX/PEBP1 complex at three sites and could disrupt the catalytically required allosteric motions of the 15LOX/PEBP1 complex. Using nine ferroptosis cell/tissue models, we show that HpETE-PE is produced by the 15LOX/PEBP1 complex and resolve the long-existing Fer-1 anti-ferroptotic paradox.

Site-Specific Peroxidation Modulates Lipid Bilayer Mechanics

Peroxidation of plasma membranes, characterized by oxidative attack of lipidic carbon-carbon double-bonds in unsaturated fatty acids, has been identified as an important biochemical event in multiple pathological conditions, including neurodegenerative diseases, atherosclerosis, diabetes, preeclampsia, aging, cancer, etc. Changes to the lipid bilayer structure as a result of lipid peroxidation may lead to lipid membrane malfunction, and consequently initiate further downstream biochemical cascades. However, how lipid peroxidation modulates the mechanical properties of lipid membranes remains largely controversial. In this study, we investigate the peroxidation of lipids with polyunsaturated fatty acid tails using molecular dynamics simulations. By systematically varying the oxidation site, we find that lipid peroxidation alters the biophysical properties of bilayer membrane in a peroxidation site-specific manner. Specifically, our results suggest that peroxidation at sites in the bilayer interior disturbs and softens the membrane, whereas peroxidation at sites near the membrane-water interface results in a more ordered and stiffer membrane. Such a peroxidation site-specific modulation of lipid membrane mechanics provides an explanation for the contradictory results obtained in previous experiments. Our study paves the way for an improved understanding of the initiation of the downstream cellular dysfunction caused by lipid peroxidation.

Unc-13 homolog D mediates an antiviral effect of the chromosome 19 microRNA cluster miR-517a

The function of microRNAs (miRNAs) can be cell autonomous or communicated to other cell types and has been implicated in diverse biological processes. We previously demonstrated that miR-517a-3p (miR-517a), a highly expressed member of the chromosome 19 miRNA cluster (C19MC) that is transcribed almost exclusively in human trophoblasts, attenuates viral replication via induction of autophagy in non-trophoblastic recipient cells. However, the molecular mechanisms underlying these effects remain unknown. Here, we identified unc-13 homolog D (UNC13D) as a direct, autophagy-related gene target of miR-517a, leading to repression of UNC13D. In line with the antiviral activity of miR-517a, silencing UNC13D suppressed replication of vesicular stomatitis virus (VSV), whereas overexpression of UNC13D increased VSV levels, suggesting a role for UNC13D silencing in the antiviral activity of miR-517a. We also found that miR-517a activated NF-κB signaling in HEK-293XL cells expressing TLR8, but the effect was not specific to C19MC miRNA. Taken together, our results define mechanistic pathways that link C19MC miRNA with inhibition of viral replication.

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.

Transgenic expression of human C19MC miRNAs impacts placental morphogenesis

INTRODUCTION

The chromosome 19 miRNA cluster (C19MC) encodes a large family of microRNAs (miRNAs) that are abundantly expressed in the placenta of higher primates and also in certain cancers. In the placenta, miRNAs from this cluster account for nearly 40% of all miRNAs present in trophoblasts. However, the function of these miRNAs in the placenta remains poorly understood. Recent observations reveal a role for these miRNAs in cell migration, and suggest that they are involved in the development and function of the human placenta. Here, we examine the placenta in transgenic mice expressing the human C19MC miRNAs.

METHODS

We produced transgenic mice using pronuclear microinjection of a bacterial artificial chromosome plasmid carrying the entire human C19MC locus and derived a homozygous line using crossbreeding. We performed morphological characterization and profiled gene expression changes in the placentas of the transgenic mice.

RESULTS

C19MC transgenic mice delivered on time with no gross malformations. The placentas of transgenic mice expressed C19MC miRNAs and were larger than wild type placentas. Histologically, we found that the transgenic placenta exhibited projections of spongiotrophoblasts that penetrated deep into the labyrinth. Gene expression analysis revealed alterations in the expression of several genes involved in cell migration, with evidence of enhanced cell proliferation.

DISCUSSION

Mice that were humanized for transgenically overexpressed C19MC miRNAs exhibit enlarged placentas with aberrant delineation of cell layers. The observed phenotype and the related gene expression changes suggest disrupted migration of placental cell subpopulations.

Correction: Separating extracellular vesicles and lipoproteins via acoustofluidics

Correction for 'Separating extracellular vesicles and lipoproteins via acoustofluidics' by Mengxi Wu et al., Lab Chip, 2019, 19, 1174-1182, DOI: .

Advancing human health in the decade ahead: pregnancy as a key window for discovery: A Burroughs Wellcome Fund Pregnancy Think Tank

Recent revolutionary advances at the intersection of medicine, omics, data sciences, computing, epidemiology, and related technologies inspire us to ponder their impact on health. Their potential impact is particularly germane to the biology of pregnancy and perinatal medicine, where limited improvement in health outcomes for women and children has remained a global challenge. We assembled a group of experts to establish a Pregnancy Think Tank to discuss a broad spectrum of major gestational disorders and adverse pregnancy outcomes that affect maternal-infant lifelong health and should serve as targets for leveraging the many recent advances. This report reflects avenues for future effects that hold great potential in 3 major areas: developmental genomics, including the application of methodologies designed to bridge genotypes, physiology, and diseases, addressing vexing questions in early human development; gestational physiology, from immune tolerance to growth and the timing of parturition; and personalized and population medicine, focusing on amalgamating health record data and deep phenotypes to create broad knowledge that can be integrated into healthcare systems and drive discovery to address pregnancy-related disease and promote general health. We propose a series of questions reflecting development, systems biology, diseases, clinical approaches and tools, and population health, and a call for scientific action. Clearly, transdisciplinary science must advance and accelerate to address adverse pregnancy outcomes. Disciplines not traditionally involved in the reproductive sciences, such as computer science, engineering, mathematics, and pharmacology, should be engaged at the study design phase to optimize the information gathered and to identify and further evaluate potentially actionable therapeutic targets. Information sources should include noninvasive personalized sensors and monitors, alongside instructive "liquid biopsies" for noninvasive pregnancy assessment. Future research should also address the diversity of human cohorts in terms of geography, racial and ethnic distributions, and social and health disparities. Modern technologies, for both data-gathering and data-analyzing, make this possible at a scale that was previously unachievable. Finally, the psychosocial and economic environment in which pregnancy takes place must be considered to promote the health and wellness of communities worldwide.

Internalization of trophoblastic small extracellular vesicles and detection of their miRNA cargo in P-bodies

Pregnancy is a unique situation, in which placenta-derived small extracellular vesicles (sEVs) may communicate with maternal and foetal tissues. While relevant to homoeostatic and pathological functions, the mechanisms underlying sEV entry and cargo handling in target cells remain largely unknown. Using fluorescently or luminescently labelled sEVs, derived from primary human placental trophoblasts or from a placental cell line, we interrogated the endocytic pathways used by these sEVs to enter relevant target cells, including the neighbouring primary placental fibroblasts and human uterine microvascular endothelial cells. We found that trophoblastic sEVs can enter target cells, where they retain biological activity. Importantly, using a broad series of pharmacological inhibitors and siRNA-dependent silencing approaches, we showed that trophoblastic sEVs enter target cells using macropinocytosis and clathrin-mediated endocytosis pathways, but not caveolin-dependent endocytosis. Tracking their intracellular course, we localized the sEVs to early endosomes, late endosomes, and lysosomes. Finally, we used coimmunoprecipitation to demonstrate the association of the sEV microRNA (miRNA) with the P-body proteins AGO2 and GW182. Together, our data systematically detail endocytic pathways used by placental sEVs to enter relevant fibroblastic and endothelial target cells, and provide support for “endocytic escape” of sEV miRNA to P-bodies, a key site for cytoplasmic RNA regulation.

Increasing NIH funding for academic departments of obstetrics and gynecology: a call to action

The National Institutes of Health funding for reproductive sciences research, specifically in academic departments of obstetrics and gynecology, is disproportionately low. Research is one of the most important pillars in advancing healthcare. Despite US Congress' vision in providing increased funding to the National Institutes of Health as a whole, underfunding for research in the departments of obstetrics and gynecology remains one of the several critical drivers in the decline in reproductive health and healthcare for women in the United States.

Cervicovaginal fluid proteomic analysis to identify potential biomarkers for preterm birth

BACKGROUND

Spontaneous preterm birth is a leading cause of neonatal morbidity and mortality. Early identification of at-risk women by reliable screening tests could reduce the spontaneous preterm birth rate, but conventional methods such as obstetrical history and maternal cervical length screening identify only a minority of spontaneous preterm birth cases. Cervicovaginal fluid might prove to be a useful, readily available biological fluid for identifying spontaneous preterm birth biomarkers.

OBJECTIVE

The objective of the study was to identify cervicovaginal fluid biomarkers of early spontaneous preterm birth in a high-risk cohort of pregnant women with a history of spontaneous preterm birth using targeted and shotgun proteomic analyses.

STUDY DESIGN

A nested case control study (cases were spontaneous preterm birth <34 weeks in the current pregnancy; controls were spontaneous labor and delivery at 39-41 weeks) was performed using cervicovaginal fluid samples collected at 3 study visits (100/7 to 186/7 weeks, 190/7 to 236/7 weeks, and 280/7 to 316/7 weeks). All participants had a history of at least 1 prior spontaneous preterm birth. Targeted proteomic analysis was performed using a stable isotope-labeled proteome derived from endocervical and vaginal mucosal cells. This served as a standard to quantitate candidate protein levels in individual cervicovaginal fluid samples from the second and third study visits using liquid chromatography-multiple reaction monitoring mass spectrometry. The ratio of endogenous peptide area/stable isotope-labeled proteome-derived peptide area was used to measure levels of 42 peptides in 22 proteins. To maximize biomarker discovery in the cervicovaginal fluid samples, shotgun proteomic analysis also was performed utilizing liquid chromatography and ion trap mass spectrometry. A validation study was performed in second-trimester cervicovaginal fluid samples from an independent study group (12 spontaneous preterm birth cases, 19 term delivery controls) using enzyme-linked immunosorbent assay for 5 proteins expressed at higher levels in spontaneous preterm birth cases compared with controls in targeted or shotgun proteomic analyses.

RESULTS

For targeted proteomics, cervicovaginal fluid samples from 33 cases and 32 controls at 190/7 to 236/7 weeks and 16 cases and 14 controls at 280/7 to 316/7 weeks from the same pregnancies were analyzed. When samples were compared between cases and controls, the relative abundance of 5 proteins was greater (P = .02-.05) in cases at both visits, while the relative abundance of 1 protein was lower (P = .03) in cases at both visits. For shotgun proteomics analyses, cervicovaginal fluid samples were pooled for 9 spontaneous preterm birth cases and 9 term delivery controls at each study visit. Shotgun proteomics yielded 28 proteins that were detected at levels >2 times higher and 1 protein that was detected at a level <0.5 times lower in spontaneous preterm birth cases compared with controls at all 3 study visits. Validation enzyme-linked immunosorbent assay for 5 proteins that were detected at higher levels in cervicovaginal fluid samples from spontaneous preterm birth cases compared with term delivery controls in proteomics analyses did not demonstrate statistically significant differences between spontaneous preterm birth cases and controls.

CONCLUSIONS

Potential biomarkers of spontaneous preterm birth were identified by targeted and shotgun proteomics analyses in cervicovaginal fluid samples from high-risk, asymptomatic women. Many of the proteins detected at higher levels in cervicovaginal fluid samples from spontaneous preterm birth cases are extracellular matrix proteins and/or regulate cell membrane physiology. These proteins have substantial biological interest, but validation enzyme-linked immunosorbent assay for 5 of these proteins did not yield clinically useful biomarkers for spontaneous preterm birth.

Placental small extracellular vesicles: Current questions and investigative opportunities

The discovery of regulated trafficking of extracellular vesicles (EVs) has added a new dimension to our understanding of local and distant communication among cells and tissues. Notwithstanding the expanded landscape of EV subtypes, the majority of research in the field centers on small and large EVs that are commonly termed exosomes, microvesicles and apoptotic cell-derived vesicles. In the context of pregnancy, EV-based communication has a special role in the crosstalk among the placenta, maternal and fetal compartments, with most studies focusing on trophoblastic EVs and their effect on other placental cell types, endothelial cells, and distant tissues. Many unanswered questions in the field of EV biology center on the mechanisms of vesicle biogenesis, loading of cargo molecules, EV release and trafficking, the interaction of EVs with target cells and the endocytic pathways underlying their uptake, and the intracellular processing of EVs inside target cells. These questions are directly relevant to EV-based placental-maternal-fetal communication and have unique implications in the context of interaction between two organisms. Despite rapid progress in the field, the number of speculative, unsubstantiated assumptions about placental EVs is concerning. Here we attempt to delineate existing knowledge in the field, focusing primarily on placental small EVs (exosomes). We define central questions that require investigative attention in order to advance the field.

Unique microRNA Signals in Plasma Exosomes from Pregnancies Complicated by Preeclampsia

Although preeclampsia is a common and serious complication of pregnancy, insight into its pathobiology and diagnosis is lacking. Circulating plasma exosomes, which contain RNA and other molecules and have recently become accessible for diagnostics, may be informative in this regard. We tested the hypothesis that preeclampsia may affect the miRNA cargo within circulating maternal blood exosomes. We collected plasma from 60 pregnant women at term, including 20 women with pregnancy complicated by preeclampsia, and 20 women with fetal growth restriction and 20 with healthy pregnancy, serving as controls. We isolated exosomes from the maternal plasma by continuous density gradient ultracentrifugation. Our main outcome variable was exosomal miRNA cargo, analyzed by quantitative polymerase chain reaction-based TaqMan advanced miRNA assay in a card format and the expression of differentially expressed exosomal miRNA in whole plasma from the same participants. We found that 7 miRNA species were differentially expressed in exosomes from women with preeclampsia and those from controls. In contrast, there was no significant difference in exosomal miRNA expression between women with fetal growth restriction and controls. The results were not affected by fetal sex. Only one of the preeclampsia-related, differentially expressed exosomal miRNAs was significantly different in whole plasma miRNA analysis. We concluded that unlike whole plasma miRNA, exosomes extracted from the plasma of women with preeclampsia exhibit a unique miRNA profile, suggesting that plasma exosomal miRNA could provide insight into the pathophysiology of preeclampsia, and may play a role in disease diagnostics.

Optimal timing of antenatal corticosteroid administration and preterm neonatal and early childhood outcomes

Background

Antenatal corticosteroids reduce morbidity and mortality among preterm neonates. However, the optimal timing of steroid administration with regards to severe neonatal and early childhood morbidity is uncertain.

Objective

To evaluate the association between the timing of antenatal corticosteroid adminstration and preterm outcomes. We hypothesized that neonates exposed to antenatal corticosteroids 2 to <7 days before delivery would have the lowest risks of neonatal and childhood morbidity.

Study Design

Secondary analysis of two prospective multicenter studies enriched for spontaneous preterm birth, Genomics and Proteomics Network for Preterm Birth Research (11/2007-1/2011) and Beneficial Effect of Antenatal Magnesium (12/1997-5/2004). We included women with singleton gestations who received antenatal corticosteroids and delivered at 23 0/7-33 6/7 weeks' gestation. Women who received ≥1 course of corticosteroids were excluded. Neonatal outcomes were compared by the timing of the first dose of antenatal corticosteroids in relation to delivery: <2 days, 2 to <7 days, 7 to <14 days, and ≥14 days. The primary outcome was respiratory distress syndrome. Secondary outcomes included composite neonatal morbidity (death, intraventricular hemorrhage grade III or IV, periventricular leukomalacia, bronchopulmonary dysplasia, or necrotizing enterocolitis), and early childhood morbidity (death or moderate to severe cerebral palsy at age 2). Multivariable logistic regression estimated the association between timing of antenatal corticosteroid administration and study outcomes.

Results

A total of 2,259 subjects met inclusion criteria: 622 (27.5%) received antenatal corticosteroids <2 days before delivery, 821 (36.3%) 2 to <7 days, 401 (17.8%) 7 to <14 days, and 415 (18.4%) ≥14 days. The majority (78.1%) delivered following idiopathic spontaneous preterm labor or preterm premature rupture of membranes at a mean gestational age of 29.5 +/-2.8 weeks. Neonates exposed to antenatal corticosteroids 2 to <7 days before delivery were the least likely to develop respiratory distress syndrome (51.3%), compared to those receiving antenatal corticosteroids <2 days, 7 to <14 days, and ≥14 days before delivery (62.7%, 55.9%, and 57.6%, respectively, p<0.001). Compared to receipt 2 to <7 days before delivery, there was an increased odds of respiratory distress syndrome with receipt of antenatal corticosteroids <2 days (aOR 2.07, 95%CI 1.61-2.66), 7 to <14 days (aOR 1.40, 95% CI 1.07-1.83), and ≥14 days (aOR 2.34, 95%CI 1.78-3.07). Neonates exposed to antenatal corticosteroids ≥14 days before delivery were at increased odds for severe neonatal morbidity (aOR 1.57, 95%CI 1.12-2.19) and early childhood morbidity (aOR 1.74, 95%CI 1.02-2.95), compared to those exposed 2 to <7 days before delivery. There was no significant association between antenatal corticosteroid receipt <2 days or 7 to <14 days and severe neonatal morbidity or severe childhood morbidity.

Conclusions

Preterm neonates exposed to antenatal corticosteroids 2 to <7 days before delivery had the lowest odds of respiratory distress syndrome, compared to shorter and longer time intervals between steroid administration and delivery. Antenatal corticosteroid administration ≥14 days before delivery is associated with an increased odds of severe neonatal and childhood morbidity, compared to 2 to <7 days before delivery. These results emphasize the importance of optimally timed antenatal corticosteroids to improve both short- and long-term outcomes.

Pyroptosis is a critical inflammatory pathway in the placenta from early onset preeclampsia and in human trophoblasts exposed to hypoxia and endoplasmic reticulum stressors

Systemic manifestation of preeclampsia (PE) is associated with circulating factors, including inflammatory cytokines and damage-associated molecular patterns (DAMPs), or alarmins. However, it is unclear whether the placenta directly contributes to the increased levels of these inflammatory triggers. Here, we demonstrate that pyroptosis, a unique inflammatory cell death pathway, occurs in the placenta predominantly from early onset PE, as evidenced by elevated levels of active caspase-1 and its substrate or cleaved products, gasdermin D (GSDMD), IL-1β, and IL-18. Using cellular models mimicking pathophysiological conditions (e.g., autophagy deficiency, hypoxia, and endoplasmic reticulum (ER) stress), we observed that pyroptosis could be induced in autophagy-deficient human trophoblasts treated with sera from PE patients as well as in primary human trophoblasts exposed to hypoxia. Exposure to hypoxia elicits excessive unfolded protein response (UPR) and ER stress and activation of the NOD-like receptor pyrin-containing 3 (NLRP3) inflammasome in primary human trophoblasts. Thioredoxin-interacting protein (TXNIP), a marker for hyperactivated UPR and a crucial signaling molecule linked to NLRP3 inflammasome activation, is significantly increased in hypoxia-treated trophoblasts. No evidence was observed for necroptosis-associated events. Importantly, these molecular events in hypoxia-treated human trophoblasts are significantly observed in placental tissue from women with early onset PE. Taken together, we propose that placental pyroptosis is a key event that induces the release of factors into maternal circulation that possibly contribute to severe sterile inflammation and early onset PE pathology.

Platelet-derived extracellular vesicles released after trauma promote hemostasis and contribute to DVT in mice

BACKGROUND

Traumatic injury can lead to dysregulation of the normal clotting system, resulting in hemorrhagic and thrombotic complications. Platelet activation is robust following traumatic injury and one process of platelet activation is to release of extracellular vesicles (PEV) that carry heterogenous cargo loads and surface ligands.

OBJECTIVES

We sought to investigate and characterize the release and function of PEVs generated following traumatic injury.

METHODS

PEV content and quantity in circulation following trauma in humans and mice was measured using flow cytometry, size exclusion chromatography, and nanoparticle tracking analysis. PEVs were isolated from circulation and the effects on thrombin generation, bleeding time, hemorrhage control, and thrombus formation were determined. Finally, the effect of hydroxychloroquine (HCQ) on PEV release and thrombosis were examined.

RESULTS

Human and murine trauma results in a significant release of PEVs into circulation compared with healthy controls. These PEVs result in abundant thrombin generation, increased platelet aggregation, decreased bleeding times, and decreased hemorrhage in uncontrolled bleeding. Conversely, PEVs contributed to enhanced venous thrombus formation and were recruited to the developing thrombus site. Interestingly, HCQ treatment resulted in decreased platelet aggregation, decreased PEV release, and reduced deep vein thrombosis burden in mice.

CONCLUSIONS

These data demonstrate that trauma results in significant release of PEVs which are both pro-hemostatic and pro-thrombotic. The effects of PEVs can be mitigated by treatment with HCQ, suggesting the potential use as a form of deep vein thrombosis prophylaxis.

The biology of extracellular vesicles: The known unknowns

For many years, double-layer phospholipid membrane vesicles, released by most cells, were not considered to be of biological significance. This stance has dramatically changed with the recognition of extracellular vesicles (EVs) as carriers of biologically active molecules that can traffic to local or distant targets and execute defined biological functions. The dimensionality of the field has expanded with the appreciation of diverse types of EVs and the complexity of vesicle biogenesis, cargo loading, release pathways, targeting mechanisms, and vesicle processing. With the expanded interest in the field and the accelerated rate of publications on EV structure and function in diverse biomedical fields, it has become difficult to distinguish between well-established biological features of EV and the untested hypotheses or speculative assumptions that await experimental proof. With the growing interest despite the limited evidence, we sought in this essay to formulate a set of unsolved mysteries in the field, sort out established data from fascinating hypotheses, and formulate several challenging questions that must be answered for the field to advance.

Separating extracellular vesicles and lipoproteins via acoustofluidics

Extracellular vesicles (EVs) and lipoproteins are abundant and co-exist in blood. Both have been proven to be valuable as diagnostic biomarkers and for therapeutics. However, EVs and lipoproteins are both on the submicron scale and overlap in size distributions. Conventional methods to separate EVs and lipoproteins are inefficient and time-consuming. Here we present an acoustofluidic-based separation technique that is based on the acoustic property differences of EVs and lipoproteins. By using the acoustofluidic technology, EVs and subgroups of lipoproteins are separated in a label-free, contact-free, and continuous manner. With its ability for simple, rapid, efficient, continuous-flow isolation, our acoustofluidic technology could be a valuable tool for health monitoring, disease diagnosis, and personalized medicine.

PLIN2 Is Essential for Trophoblastic Lipid Droplet Accumulation and Cell Survival During Hypoxia

Trophoblast hypoxia and injury, key components of placental dysfunction, are associated with fetal growth restriction and other complications of pregnancy. Accumulation of lipid droplets has been found in hypoxic nonplacental cells. Unique to pregnancy, lipid accumulation in the placenta might perturb lipid transport to the fetus. We tested the hypothesis that hypoxia leads to accumulation of lipid droplets in human trophoblasts and that trophoblastic PLIN proteins play a key role in this process. We found that hypoxia promotes the accumulation of lipid droplets in primary human trophoblasts. A similar accretion of lipid droplets was found in placental villi in vivo from pregnancies complicated by fetal growth restriction. In both situations, these changes were associated with an increased level of cellular triglycerides. Exposure of trophoblasts to hypoxia led to reduced fatty acid efflux and oxidation with no change in fatty acid uptake or synthesis. We further found that hypoxia markedly stimulated PLIN2 mRNA synthesis and protein expression, which colocalized to lipid droplets. Knockdown of PLIN2, but not PLIN3, enhanced trophoblast apoptotic death, and overexpression of PLIN2 promoted cell viability. Collectively, our data indicate that hypoxia enhances trophoblastic lipid retention in the form of lipid droplets and that PLIN2 plays a key role in this process and in trophoblast defense against apoptotic death. These findings also imply that this protective mechanism may lead to diminished trafficking of lipids to the developing fetus.

"Only a Life Lived for Others Is Worth Living": Redox Signaling by Oxygenated Phospholipids in Cell Fate Decisions

SIGNIFICANCE

Oxygenated polyunsaturated lipids are known to play multi-functional roles as essential signals coordinating metabolism and physiology. Among them are well-studied eicosanoids and docosanoids that are generated via phospholipase A2 hydrolysis of membrane phospholipids and subsequent oxygenation of free polyunsaturated fatty acids (PUFA) by cyclooxygenases and lipoxygenases. Recent Advances: There is an emerging understanding that oxygenated PUFA-phospholipids also represent a rich signaling language with yet-to-be-deciphered details of the execution machinery-oxygenating enzymes, regulators, and receptors. Both free and esterified oxygenated PUFA signals are generated in cells, and their cross-talk and inter-conversion through the de-acylation/re-acylation reactions is not sufficiently explored.

CRITICAL ISSUES

Here, we review recent data related to oxygenated phospholipids as important damage signals that trigger programmed cell death pathways to eliminate irreparably injured cells and preserve the health of multicellular environments. We discuss the mechanisms underlying the trans-membrane redistribution and generation of oxygenated cardiolipins in mitochondria by cytochrome c as pro-apoptotic signals. We also consider the role of oxygenated phosphatidylethanolamines as proximate pro-ferroptotic signals.

FUTURE DIRECTIONS

We highlight the importance of sequential processes of phospholipid oxygenation and signaling in disease contexts as opportunities to use their regulatory mechanisms for the identification of new therapeutic targets.

Distinct communication patterns of trophoblastic miRNA among the maternal-placental-fetal compartments

INTRODUCTION

The placenta produces microRNAs (miRNA) that may traffic to the maternal or fetal compartments and influence the physiology of pregnancy. The trafficking patterns of miRNA expressed from the large human chromosome 19 and chromosome 14 clusters (C19MC and C14MC), remains unclear. We interrogated the cross-sectional landscape of miRNA expression within the human placenta, fetal and maternal plasma to elucidate miRNA trafficking. We hypothesized that C19MC and C14MC miRNAs have similar expression patterns across the maternal-fetal compartments.

METHODS

Placental biopsies, maternal and fetal venous plasma were collected from 25 pregnancies, and RNA was quantified using next generation sequencing. We identified expression and correlations differences among the compartments, and uncovered distinct miRNA expression patterns using consensus clustering.

RESULTS

We found that the placenta exhibits the highest total abundance, average miRNA expression and lowest variance of both C19MC and C14MC miRNAs. The C19MC miRNAs had a comparable expression and variance in fetal and maternal plasma and higher expression in the placenta. In contrast, the C14MC miRNAs had comparable expression between the placenta and fetal plasma, which was higher than the maternal plasma. We also identified 5 distinct groups of trophoblastic miRNAs with different expression patterns in each compartment.

DISCUSSION

This is the first comprehensive analysis of C19MC and C14MC miRNA expression patterns in the human placental, maternal and fetal compartments. Our findings suggest that C14MC miRNAs are produced by both the fetus and placenta, but C19MC miRNAs are produced primarily in the placenta and are trafficked to the fetal and maternal compartments.

Advances, challenges, and opportunities in extracellular RNA biology: insights from the NIH exRNA Strategic Workshop

Extracellular RNA (exRNA) has emerged as an important transducer of intercellular communication. Advancing exRNA research promises to revolutionize biology and transform clinical practice. Recent efforts have led to cutting-edge research and expanded knowledge of this new paradigm in cell-to-cell crosstalk; however, gaps in our understanding of EV heterogeneity and exRNA diversity pose significant challenges for continued development of exRNA diagnostics and therapeutics. To unravel this complexity, the NIH convened expert teams to discuss the current state of the science, define the significant bottlenecks, and brainstorm potential solutions across the entire exRNA research field. The NIH Strategic Workshop on Extracellular RNA Transport helped identify mechanistic and clinical research opportunities for exRNA biology and provided recommendations on high priority areas of research that will advance the exRNA field.

Research to knowledge: promoting the training of physician-scientists in the biology of pregnancy

Common disorders of pregnancy, such as preeclampsia, preterm birth, and fetal growth abnormalities, continue to challenge perinatal biologists seeking insights into disease pathogenesis that will result in better diagnosis, therapy, and disease prevention. These challenges have recently been intensified with discoveries that associate gestational diseases with long-term maternal and neonatal outcomes. Whereas modern high-throughput investigative tools enable scientists and clinicians to noninvasively probe the maternal-fetal genome, epigenome, and other analytes, their implications for clinical medicine remain uncertain. Bridging these knowledge gaps depends on strengthening the existing pool of scientists with expertise in basic, translational, and clinical tools to address pertinent questions in the biology of pregnancy. Although PhD researchers are critical in this quest, physician-scientists would facilitate the inquiry by bringing together clinical challenges and investigative tools, promoting a culture of intellectual curiosity among clinical providers, and helping transform discoveries into relevant knowledge and clinical solutions. Uncertainties related to future administration of health care, federal support for research, attrition of physician-scientists, and an inadequate supply of new scholars may jeopardize our ability to address these challenges. New initiatives are necessary to attract current scholars and future generations of researchers seeking expertise in the scientific method and to support them, through mentorship and guidance, in pursuing a career that combines scientific investigation with clinical medicine. These efforts will promote breadth and depth of inquiry into the biology of pregnancy and enhance the pace of translation of scientific discoveries into better medicine and disease prevention.

Microbial Vertical Transmission during Human Pregnancy

Congenital infections with pathogens such as Zika virus, Toxoplasma gondii, Listeria monocytogenes, Treponema pallidium, parvovirus, HIV, varicella zoster virus, Rubella, Cytomegalovirus, and Herpesviruses are a major cause of morbidity and mortality worldwide. Despite the devastating impact of microbial infections on the developing fetus, relatively little is known about how pathogens associated with congenital disease breach the placental barrier to transit vertically during human pregnancy. In this Review, we focus on transplacental transmission of pathogens during human gestation. We introduce the structure of the human placenta and describe the innate mechanisms by which the placenta restricts microbial access to the intrauterine compartment. Based on current knowledge, we also discuss the potential pathways employed by microorganisms to overcome the placental barrier and prospects for the future.

Chromosome 19 microRNAs exert antiviral activity independent from type III interferon signaling

INTRODUCTION

Cultured primary human trophoblasts (PHT), derived from term placentas, are relatively resistant to infection by diverse viruses. The resistance can be conferred to non-trophoblastic cells by pre-exposing them to medium that was conditioned by PHT cells. This antiviral effect is mediated, at least in part, by microRNAs (miRNA) expressed from the chromosome 19 microRNA cluster (C19MC). Recently we showed that PHT cells and cells pre-exposed to PHT medium are also resistant to infection by Zika virus (ZIKV), an effect mediated by the constitutive release of the type III interferons (IFN) IFN lambda-1 and IFN lambda-2 in trophoblastic medium. We hypothesized that trophoblastic C19MC miRNA are active against ZIKV, and assessed the interaction of this pathway with IFN lambda-1 - mediated resistance.

METHODS

Term PHT cells were cultured using standard techniques. An osteosarcoma cell line (U2OS) was used as non-trophoblastic cells, which were infected with either ZIKV or vesicular stomatitis virus (VSV). Trophoblastic extracellular vesicles (EVs) were produced by gradient ultracentrifugation. RT-qPCR was used to determine viral infection, cellular or medium miRNA levels and the expression of interferon-stimulated genes.

RESULTS

We showed that C19MC miRNA attenuate infection of U2OS cells by ZIKV, and that C19MC miRNA or exosomes that contain C19MC miRNA did not influence the type III IFN pathway. Similarly, cell exposure to recombinant IFN lambda-1 had no effect on miRNA expression, and these pathways did not exhibit synergistic interaction.

DISCUSSION

PHT cells exert antiviral activity by at least two independent mechanisms, mediated by C19MC miRNA and by type III IFNs.

Onset of human preterm and term birth is related to unique inflammatory transcriptome profiles at the maternal fetal interface

Background

Preterm birth is a main determinant of neonatal mortality and morbidity and a major contributor to the overall mortality and burden of disease. However, research of the preterm birth is hindered by the imprecise definition of the clinical phenotype and complexity of the molecular phenotype due to multiple pregnancy tissue types and molecular processes that may contribute to the preterm birth. Here we comprehensively evaluate the mRNA transcriptome that characterizes preterm and term labor in tissues comprising the pregnancy using precisely phenotyped samples. The four complementary phenotypes together provide comprehensive insight into preterm and term parturition.

Methods

Samples of maternal blood, chorion, amnion, placenta, decidua, fetal blood, and myometrium from the uterine fundus and lower segment (n = 183) were obtained during cesarean delivery from women with four complementary phenotypes: delivering preterm with (PL) and without labor (PNL), term with (TL) and without labor (TNL). Enrolled were 35 pregnant women with four precisely and prospectively defined phenotypes: PL (n = 8), PNL (n = 10), TL (n = 7) and TNL (n = 10). Gene expression data were analyzed using shrunken centroid analysis to identify a minimal set of genes that uniquely characterizes each of the four phenotypes. Expression profiles of 73 genes and non-coding RNA sequences uniquely identified each of the four phenotypes. The shrunken centroid analysis and 10 times 10-fold cross-validation was also used to minimize false positive finings and overfitting. Identified were the pathways and molecular processes associated with and the cis-regulatory elements in gene’s 5′ promoter or 3′-UTR regions of the set of genes which expression uniquely characterized the four phenotypes.

Results

The largest differences in gene expression among the four groups occurred at maternal fetal interface in decidua, chorion and amnion. The gene expression profiles showed suppression of chemokines expression in TNL, withdrawal of this suppression in TL, activation of multiple pathways of inflammation in PL, and an immune rejection profile in PNL. The genes constituting expression signatures showed over-representation of three putative regulatory elements in their 5′and 3′ UTR regions.

Conclusions

The results suggest that pregnancy is maintained by downregulation of chemokines at the maternal-fetal interface. Withdrawal of this downregulation results in the term birth and its overriding by the activation of multiple pathways of the immune system in the preterm birth. Complications of the pregnancy associated with impairment of placental function, which necessitated premature delivery of the fetus in the absence of labor, show gene expression patterns associated with immune rejection.