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

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.