Unfolding the role of placental-derived Extracellular Vesicles in Pregnancy: From homeostasis to pathophysiology

Transcriptomics Reveals the Differences in mRNA Expression Patterns in Yak Uterus of Follicular, Luteal, and Pregnant Phases

The yak, an important livestock mostly living in the Qinghai-Tibet Plateau region, has attracted massive attention due to its reproductive specificity. However, the molecular mechanism regulating yak uterine functions remains to be explored. This study utilized transcriptomics to identify differentially expressed genes (DEGs) in yaks across uteruses undergoing the follicular phase (UFP) (n = 3/group), luteal phase (ULP) (n = 3/group), and pregnant phase (UPP) (n = 3/group), aiming to depict and compare their transcriptomic characteristics. For the UFP and ULP groups, 495 DEGs were identified, including 329 upregulated and 166 downregulated DEGs in group ULP compared to UFP. Advanced analysis indicated that these DEGs between UFP and ULP were primary participants in GO items, such as adhesion, cell differentiation, and development, and were significantly enriched in KEGG signaling pathways like arachidonic acid metabolism, retinol metabolism, and cAMP signaling pathways. For the UFP and UPP groups, 353 DEGs were obtained, comprising 198 upregulated and 155 downregulated DEGs in group UPP compared to UFP. Advanced analysis showed that these DEGs between UFP and UPP were mainly related to GO items such as adhesion, binding, and the extracellular region, and were prominently enriched in KEGG signaling pathways like ECM-receptor interaction, the relaxing signaling pathway, and focal adhesion. For the groups ULP and UPP, 1303 DEGs were identified, encompassing 709 upregulated and 594 downregulated DEGs in group UPP compared to ULP. Advanced analysis indicated that these DEGs between ULP and UPP were associated with GO items such as multicellular organismal processes, cell differentiation, and the extracellular region, and mainly gathered in KEGG signaling pathways like signal transduction, cell differentiation, metabolism, and autophagy. These results provide valuable insights into the key biomarkers observable via dynamic changes in the yak uterus and offer a theoretical basis for further studies on yak reproductive mechanisms and improving production performance.

Regulatory roles of extracellular vesicles in pregnancy complications

BACKGROUND

Extracellular vesicles (EVs) are heterogeneous membranous structures released by various cell types, including large vesicles, microvesicles (MVs), and exosomes. These vesicles play crucial roles in intercellular communication within interstitial fluids and are involved in numerous physiological and pathological processes.

AIM OF REVIEW

This review aims to examine the regulatory roles of EVs in pregnancy complications, focusing on their involvement in gestational diabetes mellitus (GDM), preeclampsia (PE), and preterm birth (PTB).

KEY SCIENTIFIC CONCEPTS OF REVIEW

Placenta- and embryo-derived EVs have gained significant attention for their biological roles due to their effects on inflammation, immune response and immunomodulation. Recent research highlights the importance of EVs in embryonic development and gestation. During pregnancy, several EVs functioned in complex endocrine regulation and pregnancy complications that can affect both the mother and fetus, with long-term cardiovascular and metabolic risks. This review discusses the current evidence on how EVs modulate pregnancy outcomes and explores their biological roles in the pathology of GDM, PE, and PTB. In spite of the current difficulties in relating these findings to the pathogenesis of pregnancy complications and the insufficient evidence for clinical practice, the potential impact of specific proteins and miRNAs transported by EVs is noteworthy on the emergence of pregnancy complications. Future research should continue to explore the complex interactions mediated by EVs to develop novel diagnostic and therapeutic strategies for pregnancy-related disorders.

Exposure to Group B Streptococcus-induced chorioamnionitis alters the proteome of placental extracellular vesicles

INTRODUCTION

Group B Streptococcus (GBS) is an opportunistic pathogen that can induce chorioamnionitis (CA), increasing the risk of neurodevelopmental disorders (NDDs) in the offspring. The placenta facilitates maternal-fetal communication through the release of extracellular vesicles (EVs), which may carry inflammatory molecules such as interleukin (IL)-1. Although the role of EVs in immune modulation is well established, their specific characterization in the context of GBS-induced CA has not yet been investigated. Understanding placental-derived EVs could further define how IL-1 and other inflammatory factors contribute to NDDs.

METHODS

We used an established rat model of GBS-induced CA. EVs from control and GBS infected dams were isolated from placentas and characterized using nanoparticle tracking analysis and transmission electron microscopy. The protein content was assessed via mass spectrometry, followed by subsequent pathway analysis. ELISA was used to quantify cytokine levels.

RESULTS

GBS-infected placentas exhibited calcification and increased weight, while fetal weight decreased. Analysis of the proteome from control versus GBS placental EVs revealed distinct profiles, with many proteins involved in the innate immune response, including alarmins (S100A8/9), complement pathways, and cytokine signaling pathways. Pathway analysis highlighted IL-1α and IL-1β identified as key upstream regulators. Notably, EVs from GBS-infected males showed a 44-fold increase in intracellular IL-1β compared to controls.

DISCUSSION

These findings indicate that GBS-induced CA alters the protein content of EVs from placental cells. Our findings of increased IL-1β-associated EVs highlight the need for further investigation into the role of these cytokines from GBS-exposed placentas and their role in brain injuries leading to NDDs.

Prenatal maternal stress in rats alters the epigenetic and transcriptomic landscape of the maternal-fetal interface across four generations

Prenatal maternal stress (PNMS) determines lifetime mental and physical health. Here, we show in rats that PNMS has consequences for placental function and fetal brain development across four generations (F0-F3). Using a systems biology approach, comprehensive DNA methylation (DNAm), miRNA, and mRNA profiling revealed a moderate impact of PNMS in the F1 generation, but drastic changes in F2 and F3 generations, suggesting compounding effects of PNMS with each successive generation. Both maternal and placental miRNA gene targets included de novo DNA methyltransferases, indicating robust PNMS-induced disruption in the complex epigenetic regulatory network between miRNAs and DNAm. Transgenerational programming mainly involved genes and biological pathways associated with neurological and psychiatric diseases which were linked to maternal-fetal crosstalk facilitated by the placenta. The highly correlated placenta-brain profiles support the use of placenta as a noninvasive biomarker resource to predict pathological changes in the neonatal brain. The transgenerational persistence of critical DNAm, miRNA and mRNA signatures may explain familial non-genetic disease risks.

A novel multiple marker microarray analyzer and methodology to predict major obstetric syndromes using surface markers of circulating extracellular vesicles from maternal plasma

INTRODUCTION

Placental-derived extracellular vesicles (EVs) are nano-organelles that facilitate intercellular communication between the feto-placental unit and the mother. We evaluated a novel Multiple Microarray analyzer for identifying surface markers on plasma EVs that predict preterm delivery and preeclampsia compared to term delivery controls.

MATERIAL AND METHODS

In this prospective exploratory cohort study pregnant women between 24 and 40 gestational weeks with preterm delivery (n = 16), preeclampsia (n = 19), and matched term delivery controls (n = 15) were recruited from Bnai Zion Medical Center, Haifa, Israel. Plasma samples were tested using a multiple microarray analyzer. Glass slides with 17 antibodies against EV surface receptors - were incubated with raw plasma samples, detected by biotinylated secondary antibodies specific to EVs or placental EVs (PEVs), and labeled with cyanine 5-streptavidin. PBS and whole human IgG served as controls. The fluorescent signal ratio to negative controls was log 2 transformed and analyzed for sensitivity and specificity using the area under the receiver operating characteristics curves (AUROC). Best pair ratios of general EVs/PEVs were used for univariate analysis, and top pairs were combined for multivariate analysis. Results were validated by comparison with EVs purified using standard procedures.

RESULTS

Heatmaps differentiated surface profiles of preeclampsia, preterm delivery, and term delivery receptors on total EVs and PEVs. Similar results were obtained with enriched EVs and EVs from raw plasma. Univariate analyses identified markers predicting preterm delivery and preeclampsia over term delivery controls with AUC >0.6 and sensitivity >50% at 80% specificity. Combining the best markers in a multivariate model, preeclampsia prediction over term delivery had an AUC of 0.89 (95% CI: 0.72-1.0) with 90% sensitivity and 90% specificity, marked by inflammation (TNF RII), relaxation (placenta protein 13 (PP13)), and immune-modulation (LFA1) receptors. Preterm delivery prediction over term delivery had an AUC of 0.97 (0.94-1.0), 84% sensitivity, and 90% specificity, marked by cell adhesion (ICAM), immune suppression, and general EV markers (CD81, CD82, and Alix). Preeclampsia prediction over preterm delivery had an AUC of 0.91 (0.79-0.99) with 80% sensitivity and 90% specificity with markers for complement activation (C1q) and autoimmunity markers.

CONCLUSIONS

The new, robust EV Multi-Array analyzer and methodology offer a simple, fast diagnostic tool that reveals novel surface markers for major obstetric syndromes.

A multi-platform assessment of extracellular vesicles from the plasma and urine of women with preeclampsia

INTRODUCTION

MicroRNAs (miRNAs), packaged within extracellular vesicles (EVs), have been used to interrogate the pathogenesis of preeclampsia and to identify its biomarkers. We have previously shown that miRNA species were differentially expressed in small plasma EVs from women with preeclampsia vs healthy controls. We sought to assess the use of rapid technologies for isolation of plasma and urine EVs from parturients with preeclampsia and determine differences in the expression of selected EV miRNA species.

METHODS

We collected blood and urine samples before delivery from parturients with severe preeclampsia vs healthy controls and used size exclusion chromatography (SEC) as an acceptable standard for rapid isolation of plasma EVs. We also isolated urine and plasma EVs using ExoDisc, a rapid nanofiltration technology for EV isolation. All samples were examined using a nanoparticle tracking analyzer, immunoblotting, and RT-qPCR for selected miRNA levels.

RESULTS

Whereas the concentration of EVs was higher in the urine from preeclampsia compared to controls, we observed the opposite change in plasma EVs, with no difference in EV size. Comparing the two patient groups for miRNA levels in EVs isolated by ExoDisc or SEC, we found that EV miR-93-5p was upregulated in the plasma and urine of parturients with preeclampsia vs healthy controls. Notably, miR-31-5p was upregulated in SEC- or ExoDisc-isolated plasma EVs, and miR-92-3p was upregulated in or ExoDisc-isolated plasma or urine EVs of parturients with preeclampsia.

DISCUSSION

Technologies for rapid analysis of plasma and urine EVs and their miRNA cargo provide complementary information that might be useful for deciphering pathways leading to preeclampsia and biomarkers for this disease.

Extracellular Vesicles as Biomarkers of Pregnancy Complications

Extracellular vesicles (EVs) are double-membrane vesicles that facilitate intercellular communication and play a pivotal role in both physiological and pathological processes. A substantial body of evidence suggests that EVs play a role in the pathogenesis of various pregnancy complications. Because EVs can be detected in the peripheral blood, they are potential biomarkers for the early diagnosis of pregnancy complications and foetal developmental disorders. The majority of studies have demonstrated a correlation between alterations in the concentration of EVs and changes in their contents and the occurrence of pregnancy complications. Despite the current limitations in establishing a clear link between these findings and the pathogenesis of the disease, as well as the lack of sufficient evidence to support their use in clinical practice, it is noteworthy to highlight the potential role of specific miRNAs carried by EVs in the development of pregnancy complications. These include miR-210 and miR-136-5p for pre-eclampsia and gestational diabetes mellitus, miR-155, miR-26b-5p, miR-181a-5p, miR-495 and miR-374c for pre-eclampsia and preterm birth. The following miRNAs have been identified as potential biomarkers for preterm birth and gestational diabetes mellitus: miR-197-3p and miR-520h, miR-1323, miR-342-3p, miR-132-3p, miR-182-3p, miR-517-3p, miR-222-3p, miR-16-5p and miR-126-3p. Additionally, miR-127-3p has been linked to foetal growth restriction and preterm birth. Nevertheless, it would be premature to propose that EVs can be employed as biomarkers for pregnancy complications. Further research and the accumulation of results obtained using the methods proposed in the MISEV2023 guidelines will enable a definitive conclusion to be reached.

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

PROBLEM

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

METHOD OF STUDY

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

RESULTS

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

CONCLUSION

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

Protein Profiling of Placental Extracellular Vesicles in Gestational Diabetes Mellitus

Throughout pregnancy, some degree of insulin resistance is necessary to divert glucose towards the developing foetus. In gestational diabetes mellitus (GDM), insulin resistance is exacerbated in combination with insulin deficiency, causing new-onset maternal hyperglycaemia. The rapid reversal of insulin resistance following delivery strongly implicates the placenta in GDM pathogenesis. In this case-control study, we investigated the proteomic cargo of human syncytiotrophoblast-derived extracellular vesicles (STBEVs), which facilitate maternal-fetal signalling during pregnancy, in a UK-based cohort comprising patients with a gestational age of 38-40 weeks. Medium/large (m/l) and small (s) STBEVs were isolated from GDM (n = 4) and normal (n = 5) placentae using ex vivo dual-lobe perfusion and subjected to mass spectrometry. Bioinformatics were used to identify differentially carried proteins and mechanistic pathways. In m/lSTBEVs, 56 proteins were differently expressed while in sSTBEVs, no proteins reached statistical difference. Differences were also observed in the proteomic cargo between m/lSTBEVs and sSTBEVs, indicating that the two subtypes of STBEVs may have divergent modes of action and downstream effects. In silico functional enrichment analysis of differentially expressed proteins in m/lSTBEVs from GDM and normal pregnancy found positive regulation of cytoskeleton organisation as the most significantly enriched biological process. This work presents the first comparison of two populations of STBEVs' protein cargos (m/l and sSTBEVs) from GDM and normal pregnancy isolated using placenta perfusion. Further investigation of differentially expressed proteins may contribute to an understanding of GDM pathogenesis and the development of novel diagnostic and therapeutic tools.

Increased ferroptosis in leukocytes from preeclamptic women involving the long non-coding taurine upregulated gene 1 (TUG1)

BACKGROUND

Ferroptosis plays a key role in placental development and physiology, and abnormal ferroptosis has been implicated in trophoblast injury leading to preeclampsia (PE). We hypothesize that leukocytes isolated from PE exhibit increased ferroptosis and that extracellular vesicles contain long non-coding (lnc) RNA/mRNAs that modulate oxidative stress and iron toxicity in vascular endothelial cells.

METHODS

We measured the expression of key regulators of ferroptosis in leukocytes and extracellular vesicles as well as circulating biomarkers of iron homeostasis and oxidative stress in plasma from women with/without PE at different timepoints during pregnancy. For markers that were dysregulated, we assessed their temporal correlation with established markers of disease activity and marker of endothelial activation. For markers dysregulated in early pregnancy, we assessed their ability to predict the development of PE.

RESULTS

We found decreased lncRNA/mRNAs in leukocytes, but not extracellular vesicles, in PE that may modulate oxidative stress and iron toxicity. This decrease in anti-ferroptotic markers does not appear to be related to maternal disease activity or plasma oxidative stress status but rather to attenuated anti-inflammatory expression in these cells. Circulating ferritin was elevated in PE, supporting the hypothesis that PE represents a disbalance in iron homeostasis. Low lncRNA taurine upregulated gene 1 RNA levels in leukocytes at 22-24 weeks were strongly associated with the development of PE.

CONCLUSIONS

Our findings suggest that maternal leukocytes in PE show decreased anti-ferroptotic activity that correlates with anti-inflammatory expression. Moreover, some of these changes in ferroptotic activity appear to precede the development of PE.

Emerging role of extracellular vesicles in veterinary practice: novel opportunities and potential challenges

Extracellular vesicles are nanoscale vesicles that transport signals between cells, mediating both physiological and pathological processes. EVs facilitate conserved intercellular communication. By transferring bioactive molecules between cells, EVs coordinate systemic responses, regulating homeostasis, immunity, and disease progression. Given their biological importance and involvement in pathogenesis, EVs show promise as biomarkers for veterinary diagnosis, and candidates for vaccine production, and treatment agents. Additionally, different treatment or engineering methods could be used to boost the capability of extracellular vesicles. Despite the emerging veterinary interest, EV research has been predominantly human-based. Critical knowledge gaps remain regarding isolation protocols, cargo loading mechanisms, in vivo biodistribution, and species-specific functions. Standardized methods for veterinary EV characterization and validation are lacking. Regulatory uncertainties impede veterinary clinical translation. Advances in fundamental EV biology and technology are needed to propel the veterinary field forward. This review introduces EVs from a veterinary perspective by introducing the latest studies, highlighting their potential while analyzing challenges to motivate expanded veterinary investigation and translation.

Exploring the Role of Mediterranean and Westernized Diets and Their Main Nutrients in the Modulation of Oxidative Stress in the Placenta: A Narrative Review

Oxidative stress is a major cellular event that occurs in the placenta, fulfilling critical physiological roles in non-pathological pregnancies. However, exacerbated oxidative stress is a pivotal feature of different obstetric complications, like pre-eclampsia, fetal growth restriction, and other diseases. Compelling evidence supports the relevant role of diet during pregnancy, with pleiotropic consequences for maternal well-being. The present review aims to examine the complex background between oxidative stress and placental development and function in physiological conditions, also intending to understand the relationship between different dietary patterns and the human placenta, particularly how this could influence oxidative stress processes. The effects of Westernized diets (WDs) and high-fat diets (HFDs) rich in ultra-processed foods and different additives are compared with healthy patterns such as a Mediterranean diet (MedDiet) abundant in omega 3 polyunsaturated fatty acids, monounsaturated fatty acids, polyphenols, dietary fiber, and vitamins. Although multiple studies have focused on the role of specific nutrients, mostly in animal models and in vitro, further observational and intervention studies focusing on the placental structure and function in women with different dietary patterns should be conducted to understand the precise influence of diet on this organ.

Upregulated CXCL8 in placenta accreta spectruma regulates the migration and invasion of HTR-8/SVneo cells

BACKGROUND

Placenta accreta spectrum (PAS) is mainly characterized by excessive invasion of the uterine muscle layer accompanied by a large number of foreign blood vessels, leading to severe bleeding during and after delivery. However, the mechanism of excessive invasion of nutrient cells in placenta accreta is currently unclear.

METHODS

We performed RNA sequencing of 6 PAS patients and 4 control donors, coupled with Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses. The mRNA and protein expression of C-X-C motif ligand 8 (CXCL8) in the placental tissue was measured by qRT‒PCR, immunohistochemical staining and Western blotting. HTR-8/SVneo human villous trophoblast Neo cells were used for in vitro investigation of cell migration and invasion as well as the expression level of CXCL8.

RESULTS

A total of 1120 differentially expressed mRNAs were identified in PAS patients. Moreover, GO and KEGG analyses indicated that the differentially expressed mRNAs were most closely associated with immune system processes, biological adhesion and Wnt signaling pathway. The CXCL8 mRNA and protein levels in PAS tissue were significantly higher than those in normal placental tissue. Forced overexpression of CXCL8 significantly increased the migration and invasion of HTR-8/SVneo cells, accompanied by the upregulation of matrix metalloproteinase-2 and matrix metalloproteinase-9 and the downregulation of E-cadherin, which was reversed by knockdown of CXCL8.

CONCLUSIONS

CXCL8 was highly expressed in PAS, and knockdown of CXCL8 suppressed the migration and invasion of HTR-8/SVneo cells, suggesting its potential as a diagnostic and therapeutic target for PAS.

Elevated expression of glycolytic genes as a prominent feature of early-onset preeclampsia: insights from integrative transcriptomic analysis

Introduction: Preeclampsia (PE), a notable pregnancy-related disorder, leads to 40,000+ maternal deaths yearly. Recent research shows PE divides into early-onset (EOPE) and late-onset (LOPE) subtypes, each with distinct clinical features and outcomes. However, the molecular characteristics of various subtypes are currently subject to debate and are not consistent. Methods: We integrated transcriptomic expression data from a total of 372 placental samples across 8 publicly available databases via combat algorithm. Then, a variety of strategies including Random Forest Recursive Feature Elimination (RF-RFE), differential analysis, oposSOM, and Weighted Correlation Network Analysis were employed to identify the characteristic genes of the EOPE and LOPE subtypes. Finally, we conducted in vitro experiments on the key gene HK2 in HTR8/SVneo cells to explore its function. Results: Our results revealed a complex classification of PE placental samples, wherein EOPE manifests as a highly homogeneous sample group characterized by hypoxia and HIF1A activation. Among the core features is the upregulation of glycolysis-related genes, particularly HK2, in the placenta-an observation corroborated by independent validation data and single-cell data. Building on the pronounced correlation between HK2 and EOPE, we conducted in vitro experiments to assess the potential functional impact of HK2 on trophoblast cells. Additionally, the LOPE samples exhibit strong heterogeneity and lack distinct features, suggesting a complex molecular makeup for this subtype. Unsupervised clustering analysis indicates that LOPE likely comprises at least two distinct subtypes, linked to cell-environment interaction and cytokine and protein modification functionalities. Discussion: In summary, these findings elucidate potential mechanistic differences between the two PE subtypes, lend support to the hypothesis of classifying PE based on gestational weeks, and emphasize the potential significant role of glycolysis-related genes, especially HK2 in EOPE.

Augmented Placental Protein 13 in Placental-Associated Extracellular Vesicles in Term and Preterm Preeclampsia Is Further Elevated by Corticosteroids

Placental protein 13 (PP13) is a regulatory protein involved in remodeling the vascular system of the pregnancy and extending the immune tolerance of the mother to the growing fetus. PP13 is localized on the surface of the syncytiotrophoblast. An ex vivo placental model shows that the PP13 is released via placental-associated extracellular vesicles (PEVs) to the maternal uterine vein. This exploratory study aimed to determine PEV-associated PP13 in the maternal circulation as compared to the known soluble fraction since each has a specific communication pathway. Patients admitted to Bnai Zion Medical Center for delivery were recruited, and included 19 preeclampsia (PE) patients (7 preterm PE gestational age < 37 weeks' gestation), 16 preterm delivery (PTD, delivery at GA < 37 weeks' gestation), and 15 matched term delivery controls. Treatment by corticosteroids (Celestone), which is often given to patients with suspected preterm PE and PTD, was recorded. The PEV proteome was purified from the patients' plasma by size exclusion chromatography (SEC) to separate the soluble and PEV-associated PP13. The total level of PP13 (soluble and PEV-associated) was determined using mild detergent that depleted the PEV proteome. PP13 fractions were determined by ELISA with PP13 specific antibodies. ELISA with alkaline phosphatase (PLAP)- and cluster differentiation 63 (CD63)-specific antibodies served to verify the placental origin of the PEVs. SPSS was used for statistical analysis. The patients' medical, pregnancy, and delivery records in all groups were similar except, as expected, that a larger number of PE and PTD patients had smaller babies who were delivered earlier, and the PE patients had hypertension and proteinuria. The SEC analysis detected the presence of PP13 in the cargo of the PEVs and on their surface, in addition to the known soluble fraction. The median soluble PP13 was not significantly different across the PE, PTD, and term delivery control groups. However, after depleting the PEV of their proteome, the total PP13 (soluble and PEV-associated) was augmented in the cases of preterm PE, reaching 2153 pg/mL [IQR 1866-2838] but not in cases of PTD reaching 1576 pg/mL [1011-2014] or term delivery groups reaching 964 pg/mL [875-1636]), p < 0.01. On the surface of the circulating PEV from PTD patients, there was a decrease in PP13. Corticosteroid treatment was accompanied by a massive depletion of PP13 from the PEV, especially in preterm PE patients. This exploratory study is, thus, the first to determine PEV-associated PP13 in maternal circulation, providing a quantitative determination of the soluble and the PEV-associated fractions, and it shows that the latter is the larger. We found an increase in the amount of PP13 carried via the PEV-associated pathway in PE and PTD patients compared to term delivery cases, which was further augmented when the patients were treated with corticosteroids, especially in preterm PE. The signal conveyed by this novel communication pathway warrants further research to investigate these two differential pathways for the liberation of PP13.

Characterization of extracellular vesicles in COVID-19 infection during pregnancy

Introduction: SARS-CoV-2 infection may cause a severe inflammatory response, inflicting severe morbidity and mortality. This risk is modestly increased in pregnant patients. Despite the hypercoagulability and immunosuppression associated with pregnancy, most pregnant women experience a mild COVID-19 infection. Maternal extracellular vesicles (EVs) may interact with endothelial and immune components to facilitate a favorable disease course. This pilot study aimed to explore the characteristics of EVs released during COVID-19 infection occurring during the third trimester of pregnancy. Methods: In this prospective study, blood samples were obtained from 16 healthy non-pregnant (NP), 18 healthy-pregnant (HP), and 22 COVID-19 positive pregnant subjects (CoV-P). Disease course and pregnancy outcomes were assessed and EVs were characterized. Of note, limited volumes of sample acquired from the subjects made it necessary to use smaller and different subsets of samples for each analysis. Results: The majority (91%) of the COVID-19-pregnant subjects (18 mild and 2 moderate disease) experienced good pregnancy-related outcomes. EV concentrations were higher in healthy-pregnant subjects compared to non-pregnant subjects (p = 0.0041) and lower in COVID-19-pregnant subjects compared to healthy-pregnant subjects (p = 0.0150). CD63 exosome marker expression was higher in EVs of healthy-pregnant subjects and COVID-19-pregnant subjects compared to EVs of non-pregnant subjects (p = 0.0149, p = 0.0028, respectively). Similar levels of SARS-CoV-2 entry proteins (ACE-2 and TMPRSS2) were found in all three groups. Cytokine content increased in healthy-pregnant subject-EVs compared to non-pregnant EVs, while IL-2 and IL-6 levels were decreased in COVID-19-pregnant subject-EVs compared to healthy-pregnant subject-EVs (p = 0.043, p = 0.0390, respectively). CD8+, cytotoxic T-cell marker, was lower in non-pregnant EVs compared to healthy-pregnant subject-EVs and to COVID-19-pregnant subjects (p = 0.0108, p < 0.0001, respectively). COVID-19- pregnant subject-EVs demonstrated higher levels of platelet activation marker (CD62P) than non-pregnant (p = 0.0327) and healthy-pregnant subjects (p = 0.0365). Endothelial marker EV-CD144+ was lower in healthy-pregnant subjects versus non-pregnant subjects (p = 0.0093), but similar in COVID-19-pregnant and non-pregnant subjects. Other EVs' coagulation markers/activity, D-Dimer and fibrinogen levels were similar in healthy-pregnant subjects and COVID-19 positive pregnant subjects. Conclusion: COVID-19 positive pregnant subjects' EVs demonstrated an attenuated inflammatory response, with no additional activation of the coagulation system.