Extracellular vesicles and their immunomodulatory functions in pregnancy

"Extracellular Vesicle DNA: Advances and Applications as a Non-Invasive Biomarker in Disease Diagnosis and Treatment"

Extracellular vesicles (EVs) are nanoscale, membrane-enclosed structures released by cells into the extracellular milieu. These vesicles encapsulate a diverse array of molecular constituents, including nucleic acids, proteins, and lipids, which provide insights into the physiological or pathological conditions of their parent cells. Despite their potential, the study of EV-derived DNA (EV-DNA) has gathered relatively limited attention. This review aims to present a thorough examination of the emerging knowledge surrounding the utility of EV-DNA as a non-invasive biomarker across a spectrum of diseases. The review delves into various mechanisms underlying DNA packaging within EVs and the prevalent methodologies employed for extraction of EV-DNA. The relevance of EV-DNA is assessed across numerous health conditions, notably cancer, cardiovascular diseases, neurodegenerative disorders, infectious diseases, and pregnancy-related complications. The use of EV-DNA for cancer mutation detection has demonstrated remarkable sensitivity and specificity, thereby enhancing both diagnostic accuracy and therapeutic monitoring. In the context of cardiovascular diseases, EV-DNA serves as a predictive marker for events such as myocardial infarctions and shows a correlation with the severity of the disease. With respect to neurodegenerative conditions, including Parkinson's and Alzheimer's, EV-DNA contributes to the understanding of disease mechanisms and progression. Additionally, it plays an essential role in modulating immune tolerance and facilitating communication between maternal and fetal systems. Although there is a pressing need for standardized protocols for EV isolation and DNA analysis to facilitate clinical implementation, the prospect of EV-DNA as a non-invasive biomarker for diagnostic and prognostic purposes across diverse pathological conditions is considerable.

Upregulation of Autophagy During the Differentiation of Primary Human Term Cytotrophoblast Cells into Syncytial Cells: Ultrastructural Analysis

The villous trophoblast cells are of fundamental importance because they fulfill a variety of functions that are vital for the growth of the fetus and the maintenance of pregnancy. A simple in vitro villous trophoblast cell model that grows on standard tissue culture plates has been utilized for various functional studies on villous trophoblast cells. Despite the potential value of incorporating electron microscopy analysis in reports on functional analysis of primary human trophoblast cells, electron microscopy analysis is exclusively ancillary to functional analysis in previous publications. In the context of autophagy research of villous trophoblast cells using primary trophoblast cells, a detailed ultrastructural analysis of autophagy flux using electron microscopy is imperative; however, it has not been conducted to date. In this study, we isolated term villous trophoblast cells (i.e., cytotrophoblast cells, CTB cells) using the most up-to-date isolation method for isolating pure CTB cells from human term placenta and investigated the ultrastructural dynamic process of autophagy of cultured CTB cells by means of transmission electron microscopy. The initial 6 h culture resulted in CTB cell aggregation; however, the majority of CTB cells did not differentiate into syncytial cells. In contrast, after 72 h, CTB cells exhibited a promotion of differentiation into syncytial cells. The electron microscopy analysis revealed the upregulation of autophagy and visualized unique autophagic profiles during differentiation into syncytial cells, which exhibited perinuclear accumulation of extremely large autophagosomes/autolysosomes. This study provides novel insights into the reproductive biology of primary trophoblast cells, thereby demonstrating the substantial value of primary trophoblast cells as research resources.

Prenatal Triphenyl Phosphate Exposure and Hyperlipidemia in Offspring: Role of Trophoblast-Derived Extracellular Vesicle PPARγ

Triphenyl phosphate (TPhP) is a widely used organophosphate flame retardant, the health risks of TPhP are a global concern. In this study, we found that prenatal TPhP exposure at human relevant concentration induced hyperlipidemia in male offspring, it increased serum levels of triglyceride, total cholesterol, and low-density lipoprotein cholesterol. Placental trophoblast-derived extracellular vesicles (T-EVs) could transport to the fetus through maternal-fetal circulation. TPhP significantly upregulated the protein level of peroxisome proliferator activated receptor γ (PPARγ) in T-EVs. Similar to TPhP, gestational exposure to T-EVs isolated from TPhP exposed mice placentae induced the same effects. While, gestational intervention with GW9662 (PPARγ inhibitor) or GW4869 (EVs secretion inhibitor) would alleviate the disturbed lipid metabolism induced by TPhP. Meanwhile, in vitro experiments verified that TPhP upregulated PPARγ in HTR8/SVneo cells derived EVs, and these EVs promoted adipogenesis in preadipocyte 3T3-L1 cells. Knock down of PPARγ in HTR8/SVneo could alleviate the adipogenensis effects of EVs derived from TPhP exposed HTR8/SVneo cells. These results demonstrate that TPhP exposure induces hyperlipidemia in male offspring by upregulating PPARγ in T-EVs. Our study provides new insights into the metabolic disruptive effects of TPhP, and emphasizes the mediating effects of placental T-EVs on gestational environmental stress in fetal development.

Limosilactobacillus reuteri HY7503 and Its Cellular Proteins Alleviate Endothelial Dysfunction by Increasing Nitric Oxide Production and Regulating Cell Adhesion Molecule Levels

Endothelial dysfunction, which is marked by a reduction in nitric oxide (NO) production or an imbalance in relaxing and contracting factor levels, exacerbates atherosclerosis by promoting the production of cell adhesion molecules and cytokines. This study aimed to investigate the effects of Limosilactobacillus reuteri HY7503, a novel probiotic isolated from raw milk, on endothelial dysfunction. Five lactic acid bacterial strains were screened for their antioxidant, anti-inflammatory, and endothelium-protective properties; L. reuteri HY7503 had the most potent effect. In a mouse model of angiotensin II-induced endothelial dysfunction, L. reuteri HY7503 reduced vascular thickening (19.78%), increased serum NO levels (226.70%), upregulated endothelial NO synthase (eNOS) expression in the aortic tissue, and decreased levels of cell adhesion molecules (intercellular adhesion molecule-1 [ICAM-1] and vascular cell adhesion molecule-1 [VCAM-1]) and serum cytokines (tumor necrosis factor-alpha [TNF-α] and interleukin-6 [IL-6]). In TNF-α-treated human umbilical vein endothelial cells (HUVECs), L. reuteri HY7503 enhanced NO production and reduced cell adhesion molecule levels. In HUVECs, surface-layer proteins (SLPs) were more effective than extracellular vesicles (exosomes) in increasing NO production and decreasing cell adhesion molecule levels. These findings suggested that L. reuteri HY7503 may serve as a functional probiotic that alleviates endothelial dysfunction.

Maternal stress during pregnancy alters circulating small extracellular vesicles and enhances their targeting to the placenta and fetus

BACKGROUND

Maternal psychological distress during pregnancy can negatively impact fetal development, resulting in long-lasting consequences for the offspring. These effects show a sex bias. The mechanisms whereby prenatal stress induces functional and/or structural changes in the placental-fetal unit remain poorly understood. Maternal circulating small extracellular vesicles (sEVs) are good candidates to act as "stress signals" in mother-to-fetus communication. Using a repetitive restraint-based rat model of prenatal stress, we examined circulating maternal sEVs under stress conditions and tested whether they could target placental-fetal tissues.

RESULTS

Our mild chronic maternal stress during pregnancy paradigm induced anhedonic-like behavior in pregnant dams and led to intrauterine growth restriction (IUGR), particularly in male fetuses and placentas. The concentration and cargo of maternal circulating sEVs changed under stress conditions. Specifically, there was a significant reduction in neuron-enriched proteins and a significant increase in astrocyte-enriched proteins in blood-borne sEVs from stressed dams. To study the effect of repetitive restraint stress on the biodistribution of maternal circulating sEVs in the fetoplacental unit, sEVs from pregnant dams exposed to stress or control protocol were labeled with DiR fluorescent die and injected into pregnant females previously exposed to control or stress protocol. Remarkably, maternal circulating sEVs target placental/fetal tissues and, under stress conditions, fetal tissues are more receptive to sEVs.

CONCLUSION

Our results suggest that maternal circulating sEVs can act as novel mediators/modulators of mother-to-fetus stress communication. Further studies are needed to identify placental/fetal cellular targets of maternal sEVs and characterize their contribution to stress-induced sex-specific placental and fetal changes.

Appearance of small extracellular vesicles in the mouse pregnant serum and the localization in placentas

Exosomes or small extracellular vesicles (sEVs) are present in the blood of pregnant mice and considered to be involved in pregnancy physiology. Although sEVs in pregnant periods are proposed to be derived from placentas, sEVs-producing cells are not well known in mouse placentas. We studied the dynamics and localization of sEVs in pregnant serum and placentas, and examined gestational variation of microRNA (miRNA). Serums and placentas were collected from non-pregnant (NP) and pregnant mice throughout the entire gestational day (Gd). EVs were purified from serums and total RNA was isolated from EVs. Nanoparticle-tracking assay (NTA) revealed that the rates of sEVs in EVs are 53% at NP, and increased to 80.1% at Gd 14.5 and 97.5% at Gd 18.5. Western blotting on EVs showed positive reactivity to the tetraspanin markers and clarified that the results using anti-CD63 antibody were most consistent with the sEVs appearance detected by NTA. Serum EVs also showed a positive reaction to the syncytiotrophoblast marker, syncytin-1. Immunohistostaining using anti-CD63 antibody showed positive reactions in mouse placentas at the syncytiotrophoblasts and endothelial cells of the fetal capillaries. Quantitative PCR revealed that significantly higher amounts of miRNAs were included in the sEVs of Gd 18.5. Our results suggested that sEVs are produced in the mouse placenta and transferred to maternal or fetal bloodstreams. sEVs are expected to have a miRNA-mediated physiological effect and become useful biomarkers reflecting the pregnancy status.

Microorganism-derived extracellular vesicles: emerging contributors to female reproductive health

Extracellular vesicles (EVs) are cell-derived nanoparticles that carry small molecules, nucleic acids, and proteins long distances in the body facilitating cell-cell communication. Microorganism-derived EVs mediate communication between parent cells and host cells, with recent evidence supporting their role in biofilm formation, horizontal gene transfer, and suppression of the host immune system. As lipid-bound bacterial byproducts, EVs demonstrate improved cellular uptake and distribution in vivo compared to cell-free nucleic acids, proteins, or small molecules, allowing these biological nanoparticles to recapitulate the effects of parent cells and contribute to a range of human health outcomes. Here, we focus on how EVs derived from vaginal microorganisms contribute to gynecologic and obstetric outcomes. As the composition of the vaginal microbiome significantly impacts women's health, we discuss bacterial EVs from both healthy and dysbiotic vaginal microbiota. We also examine recent work done to evaluate the role of EVs from common vaginal bacterial, fungal, and parasitic pathogens in pathogenesis of female reproductive tract disease. We highlight evidence for the role of EVs in women's health, gaps in current knowledge, and opportunities for future work. Finally, we discuss how leveraging the innate interactions between microorganisms and mammalian cells may establish EVs as a novel therapeutic modality for gynecologic and obstetric indications.

Extracellular Vesicles: the Next Frontier in Pregnancy Research

Extracellular vehicles (EVs) have been involved in several aspects of pregnancy, including endometrial receptivity, embryo implantation, and embryo-maternal communication showing them associated with pregnancy disorders, such as preeclampsia, gestational diabetes mellitus, and preterm birth. Further research is warranted to fully comprehend the exact pathophysiological roles of EVs and to develop new therapies targeting EVs thereby improving pregnancy outcomes. Herein, we review the recent knowledge on the multifaceted roles of EVs during pregnancy and address the majority of the molecular interactions between EVs, maternal, and fetal cells with an emphasis on disorders of pregnancy under the influence of EVs. Moreover, we also discuss its applications in clinical trials followed by prospects.

Advances in extracellular vesicles as mediators of cell-to-cell communication in pregnancy

Cell-to-cell communication mediated by Extracellular Vesicles (EVs) is a novel and emerging area of research, especially during pregnancy, in which placenta derived EVs can facilitate the feto-maternal communication. EVs comprise a heterogeneous group of vesicle sub-populations with diverse physical and biochemical characteristics and originate by specific biogenesis mechanisms. EVs transfer molecular cargo (including proteins, nucleic acids, and lipids) between cells and are critical mediators of cell communication. There is growing interest among researchers to explore into the molecular cargo of EVs and their functions in a physiological and pathological context. For example, inflammatory mediators such as cytokines are shown to be released in EVs and EVs derived from immune cells play key roles in mediating the immune response as well as immunoregulatory pathways. Pregnancy complications such as gestational diabetes mellitus, preeclampsia, intrauterine growth restriction and preterm birth are associated with altered levels of circulating EVs, with differential EV cargo and bioactivity in target cells. This implicates the intriguing roles of EVs in reprogramming the maternal physiology during pregnancy. Moreover, the capacity of EVs to carry bioactive molecules makes them a promising tool for biomarker development and targeted therapies in pregnancy complications. This review summarizes the physiological and pathological roles played by EVs in pregnancy and pregnancy-related disorders and describes the potential of EVs to be translated into clinical applications in the diagnosis and treatment of pregnancy complications.

Exosome-delivered miR-410-3p reverses epithelial-mesenchymal transition, migration and invasion of trophoblasts in spontaneous abortion

Current studies have indicated that insufficient trophoblast epithelial-mesenchymal transition (EMT), migration and invasion are crucial for spontaneous abortion (SA) occurrence and development. Exosomal miRNAs play significant roles in embryonic development and cellular communication. Hereon, we explored the roles of serum exosomes derived from SA patients on trophoblast EMT, migration and invasion. Exosomes were isolated from normal control (NC) patients with abortion for unplanned pregnancy and SA patients, then characterized by transmission electron microscopy (TEM), nanoparticle tracking analysis (NTA) and western blotting. Exosomal miRNA profiles were identified by miRNA sequencing. The effects of serum exosomes on trophoblast migration and invasion were detected by scratch wound healing and transwell assays, and other potential mechanisms were revealed by quantitative real-time PCR (RT-PCR), western blotting and dual-luciferase reporter assay. Finally, animal experiments were used to explore the effects of exosomal miR-410-3p on embryo absorption in mice. The serum exosomes from SA patients inhibited trophoblast EMT and reduced their migration and invasion ability in vitro. The miRNA sequencing showed that miR-410-3p was upregulated in SA serum exosomes. The functional experiments showed that SA serum exosomes restrained trophoblast EMT, migration and invasion by releasing miR-410-3p. Mechanistically, SA serum exosomal miR-410-3p inhibited trophoblast cell EMT, migration and invasion by targeting TNF receptor-associated factor 6 (TRAF6) at the post-transcriptional level. Besides, SA serum exosomal miR-410-3p inhibited the p38 MAPK signalling pathway by targeting TRAF6 in trophoblasts. Moreover, milk exosomes loaded with miR-410-3p mimic reached the maternal-fetal interface and aggravated embryo absorption in female mice. Clinically, miR-410-3p and TRAF6 expression were abnormal and negatively correlated in the placental villi of SA patients. Our findings indicated that exosome-derived miR-410-3p plays an important role between SA serum and trophoblasts in intercellular communication, suggesting a novel mechanism by which serum exosomal miRNA regulates trophoblasts in SA patients.

BeWo exomeres are enriched for bioactive extracellular placenta-specific C19MC miRNAs

Extracellular vesicles (EVs), including exosomes, are carriers of extracellular microRNAs (miRNAs). Exomeres, non-vesicular extracellular nanoparticles (NVEPs), are novel extracellular cargo carriers. However, little is known of the characteristics of placental trophoblast-derived exomeres. In this study, we characterized trophoblast-derived exomeres and investigated the cell-cell communication of placenta-specific miRNAs carried by those exomeres using an in vitro model system (BeWo trophoblasts and Jurkat T cells). BeWo exomeres (∼ 40 nm diameter) had pilling-like nanoparticle structures, which were distinct from cup-shaped exosomes (∼ 90-110 nm diameter). BeWo cells secreted more exomeres than exosomes. Exomeres were positive for AGO2 but negative for exosome markers (CD63, CD9, CD81, FLOT1, and TSG101). The levels of placenta-specific miRNAs in exomeres were significantly higher than in exosomes. In a cell-cell communication analysis using a placenta-specific miRNA, BeWo exomeres delivered significantly more miR-517a-3p to recipient Jurkat cells compared with exosomes. Moreover, exomere-miR-517a-3p significantly reduced the expression of PRKG1 in miR-517a-3p-inhibitor (-) Jurkat cells compared with miR-517a-3p-inhibitor (+) cells, suggesting that miR-517a-3p inhibition reversed the exomere-miR-517a-3p-mediated repression of PRKG1 expression in recipient cells. Therefore, BeWo trophoblast exomeres are enriched with bioactive extracellular placenta-specific miRNAs, which were formerly considered to be carried by exosomes. Our findings provide insight into trophoblast-derived NVEPs.

Specific expression and blood kinetics for relaxin 2, lipocalin 2, and tissue factor pathway inhibitor 2 at the canine placenta and pregnant bloods

In general, humoral factors released from the placenta influence pregnancy progression, but the involvement of the canine placenta is often unidentified. We investigated specific genes in canine placentas and analyzed the blood dynamics of the translated proteins. Furthermore, RNAs are known to be released from placentas embedding in exosomes, a type of extracellular vesicles. Here, the presence of cell-free RNAs in pregnant serums was also confirmed. RNA specimens were purified from the normal healthy dog placentas and applied to RNA-Seq analysis. Expressions of frequent genes were confirmed by RT-PCR using placentas from other individuals and breeds. Relaxin (RLN) 2, lipocalin (LCN) 2, and tissue factor pathway inhibitor (TFPI) 2 were selected as high-expressed and placenta-specific genes. By western blot, the three factors were clearly detected in the pregnant serums. Quantitative analysis revealed that the amount of RLN2 increased significantly from non-pregnancy to day 41 of pregnancy. Regarding LCN2 and TFPI2, the protein serum levels elevated during pregnancy, but the statistical differences were not detected. Exosomes were found in all pregnant serums; however, the percentage was less than 6% in total extracellular vesicles. The cell-free RNA related to RLN2 was detected, but no elevation was confirmed during pregnancy. We found specific genes in the canine placenta and the transition of their translated protein into the blood. These factors may become useful tools for research on canine pregnancy and monitoring of reproductive management. Exosomes and cell-free RNA could not be found to be valid in canine reproduction.

Exosomes as a potential therapeutic approach in osteoimmunology

Exosomes are natural extracellular vesicles that play a key role in inter- and intracellular communication. Currently they are considered as a promising therapeutic strategy for the treatment of various diseases. In osteoimmunology, exosomes can serve as biomarkers of bone homeostasis disorders and, at the same time, promising therapeutic agents with high stability in the biological environment, low immunogenicity and good bioavailability. In this review, we attempted to examine exosomes as natural mediators of intercellular communication, playing an essential role in the interaction of the immune system and bone tissue, based on an analysis of the PubMed database up to October 2023.

Breaking the silence: The role of extracellular vesicles in unraveling the diagnosis and treatment of endometriosis

Cell-to-cell communication is believed to be facilitated by membrane-bound vesicles called extracellular vesicles (EVs), which are released by cells. Protein, lipids, and nucleic acids are major cargo of EVs and are transported in these vesicles. Depending on the parent and recipient cell types, they can affect a wide variety of biological processes in the tissues to which they are delivered. EVs are essential for embryo implantation and endometriosis, and they are located in the uterine cavities of different species, where they promote blastocyst and endometrial preparation for implantation. This review focuses on what is currently understood regarding pathologic and diagnostic characteristics, and the potential therapeutic value of EVs in the context of endometriosis, where they can be used for drug delivery and targeted therapy due to their ability to carry bioactive molecules to specific cells or tissues. The findings of this review highlight the potential for a wide range of clinical applications that involve endometrial EVs in the areas of treatment, such as surgical and pharmacological, diagnostic biomarker development, and drug delivery systems, all with the ultimate goal of improving pregnancy success rates.

Human umbilical cord mesenchymal stem cell-derived exosomes combined with gelatin methacryloyl hydrogel to promote fractional laser injury wound healing

To investigate whether human umbilical cord mesenchymal stem cell-derived exosomes combined with gelatin methacryloyl (GelMA) hydrogel are beneficial in promoting healing of laser-injured skin wounds in mice. Supernatants of cultured human umbilical cord mesenchymal stem cells (HUC-MSCs) were collected to obtain human umbilical cord MSC-derived exosomes (HUC-MSCs-Exos), which were combined with GelMA hydrogel complex to treat a mouse fractional laser injury model. The study was divided into PBS group, EX (HUC-MSCs-Exos) group, GEL (GelMA hydrogel) group and EX+GEL (HUC-MSCs-Exos combined with GelMA hydrogel) group. The healing of laser-injured skin in each group was observed by gross view and dermatoscopy, and changes in skin structure, angiogenesis and proliferation-related indexes were observed during the healing process of laser-injured skin in each group. The results of the animal experiments showed that the EX and GEL groups alone and the EL+EX group exhibited less inflammatory response compared to the PBS group. The EX and GEL groups showed marked tissue proliferation and favourable angiogenesis, which promoted the wound healing well. The GEL+EX group had the most significant promotion of wound healing compared to the PBS group. qPCR results showed that the expression levels of proliferation-related factors, including KI67 and VEGF and angiogenesis-related factor CD31, were significantly higher in the GEL+EX group than in the other groups, with a time-dependent effect. The combination of HUC-MSCs-Exos and GelMA hydrogel is beneficial in reducing the early inflammatory response of laser-injured skin in mice and promoting its proliferation and angiogenesis, which in turn promotes wound healing.

Placenta-derived exosomal miR-135a-5p promotes gestational diabetes mellitus pathogenesis by activating PI3K/AKT signalling pathway via SIRT1

Most people are aware of gestational diabetes mellitus (GDM), a dangerous pregnancy complication in which pregnant women who have never been diagnosed with diabetes develop chronic hyperglycaemia. Exosomal microRNA (miRNA) dysregulation has been shown to be a key player in the pathophysiology of GDM. In this study, we looked into how placental exosomes and their miRNAs may contribute to GDM. When compared to exosomes from healthy pregnant women, it was discovered that miR-135a-5p was elevated in placenta-derived exosomes that were isolated from the maternal peripheral plasma of GDM women. Additionally, we discovered that miR-135a-5p encouraged HTR-8/SVneo cell growth, invasion and migration. Further research revealed that miR-135a-5p activates HTR-8/SVneo cells' proliferation, invasion and migration by promoting PI3K/AKT pathway activity via Sirtuin 1 (SIRT1). The transfer of exosomal miR-135a-5p generated from the placenta could be viewed as a promising agent for targeting genes and pertinent pathways involved in GDM, according to our findings.

Platelet and mitochondrial RNA is decreased in plasma-derived extracellular vesicles in women with preeclampsia-an exploratory study

BACKGROUND

Circulating extracellular vesicles (EVs) are increased in preeclampsia (PE) and are associated with severity and progression. We examined in this exploratory cohort study if the mRNAs and long noncoding RNAs (lncRNAs) in plasma-derived EVs were dysregulated in PE compared to normal pregnancy and display different temporal patterns during gestation.

METHODS

We isolated EVs from plasma at weeks 22-24 and 36-38 in women with and without PE (n=7 in each group) and performed RNA-seq, focusing on mRNAs and lncRNAs. We validated highly expressed mitochondrial and platelet-derived RNAs discovered from central pathways in 60 women with/without PE. We examined further one of the regulated RNAs, noncoding mitochondrially encoded tRNA alanine (MT-TA), in leukocytes and plasma to investigate its biomarker potential and association with clinical markers of PE.

RESULTS

We found abundant levels of platelet-derived and mitochondrial RNAs in EVs. Expression of these RNAs were decreased and lncRNAs increased in EVs from PE compared to without PE. These findings were further validated by qPCR for mitochondrial RNAs MT-TA, MT-ND2, MT-CYB and platelet-derived RNAs PPBP, PF4, CLU in EVs. Decreased expression of mitochondrial tRNA MT-TA in leukocytes at 22-24 weeks was strongly associated with the subsequent development of PE.

CONCLUSIONS

Platelet-derived and mitochondrial RNA were highly expressed in plasma EVs and were decreased in EVs isolated from women with PE compared to without PE. LncRNAs were mostly increased in PE. The MT-TA in leukocytes may be a useful biomarker for prediction and/or early detection of PE.

Circulating exosomes decrease in size and increase in number between birth and age 7: relations to fetal growth and liver fat

Purpose

Exosomes play a key role in cell-to-cell communication by transferring their cargo to target tissues. Little is known on the course of exosome size and number in infants and children.

Methods

Longitudinally, we assessed the size and number of circulating exosomes at birth and at ages 2 and 7 yr in 75 infants/children born appropriate-for-gestational-age (AGA; n=40) or small-for-gestational-age (SGA; n=35 with spontaneous catch-up), and related those results to concomitantly assessed measures of endocrine-metabolic health (HOMA-IR; IGF-1), body composition (by DXA at ages 0 and 2) and abdominal fat partitioning (subcutaneous, visceral and hepatic fat by MRI at age 7).

Results

Circulating exosomes of AGAs decreased in size (on average by 4.2%) and increased in number (on average by 77%) between birth and age 7. Circulating exosomes of SGAs (as compared to those of AGAs) had a larger size at birth [146.8 vs 137.8 nm, respectively; p=0.02], and were in lower number at ages 2 [4.3x1011 vs 5.6x1011 particles/mL, respectively; p=0.01] and 7 [6.3x1011 vs 6.8x1011 particles/mL, respectively; p=0.006]. Longitudinal changes were thus more pronounced in SGAs for exosome size, and in AGAs for exosome number. At age 7, exosome size associated (P<0.0001) to liver fat in the whole study population.

Conclusion

Early-life changes in circulating exosomes include a minor decrease in size and a major increase in number, and these changes may be influenced by fetal growth. Exosome size may become one of the first circulating markers of liver fat in childhood.

Extracellular vesicles- crucial players in human pregnancy

Extracellular vesicles (EVs) are lipid-bilayer enclosed membrane vesicles released by cells in physiological and pathological states. EVs are generated and released through a variety of pathways and mediate cellular communication by carrying and transferring signals to recipient cells. EVs are specifically loaded with proteins, nucleic acids (RNAs and DNA), enzymes and lipids, and carry a range of surface proteins and adhesion molecules. EVs contribute to intercellular signalling, development, metabolism, tissue homeostasis, antigen presentation, gene expression and immune regulation. EVs have been categorised into three different subgroups based on their size: exosomes (30-150 nm), microvesicles (100-1000 nm) and apoptotic bodies (1-5 μm). The status of the cells of origin of EVs influences their biology, heterogeneity and functions. EVs, especially exosomes, have been studied for their potential roles in feto-maternal communication and impacts on normal pregnancy and pregnancy disorders. This review presents an overview of EVs, emphasising exosomes and microvesicles in a general context, and then focusing on the roles of EVs in human pregnancy and their potential as diagnostics for adverse pregnancy outcomes.

Extracellular vesicle-mediated targeting strategies for long-term health benefits in gestational diabetes

Extracellular vesicles (EVs) are critical mediators of cell communication, playing important roles in regulating molecular cross-talk between different metabolic tissues and influencing insulin sensitivity in both healthy and gestational diabetes mellitus (GDM) pregnancies. The ability of EVs to transfer molecular cargo between cells imbues them with potential as therapeutic agents. During pregnancy, the placenta assumes a vital role in metabolic regulation, with multiple mechanisms of placenta-mediated EV cross-talk serving as central components in GDM pathophysiology. This review focuses on the role of the placenta in the pathophysiology of GDM and explores the possibilities and prospects of targeting the placenta to address insulin resistance and placental dysfunction in GDM. Additionally, we propose the use of EVs as a novel method for targeted therapeutics in treating the dysfunctional placenta. The primary aim of this review is to comprehend the current status of EV targeting approaches and assess the potential application of these strategies in placental therapeutics, thereby delivering molecular cargo and improving maternal and fetal outcomes in GDM. We propose that EVs have the potential to revolutionize GDM management, offering hope for enhanced maternal-fetal health outcomes and more effective treatments.

The biological functions of maternal-derived extracellular vesicles during pregnancy and lactation and its impact on offspring health

During pregnancy and lactation, mothers provide not only nutrients, but also many bioactive components for their offspring through placenta and breast milk, which are essential for offspring development. Extracellular vesicles (EVs) are nanovesicles containing a variety of biologically active molecules and participate in the intercellular communication. In the past decade, an increasing number of studies have reported that maternal-derived EVs play a crucial role in offspring growth, development, and immune system establishment. Hereby, we summarized the characteristics of EVs; biological functions of maternal-derived EVs during pregnancy, including implantation, decidualization, placentation, embryo development and birth of offspring; biological function of breast milk-derived EVs (BMEs) on infant oral and intestinal diseases, immune system, neurodevelopment, and metabolism. In summary, emerging studies have revealed that maternal-derived EVs play a pivotal role in offspring health. As such, maternal-derived EVs may be used as promising biomarkers in offspring disease diagnosis and treatment. However, existing research on maternal-derived EVs and offspring health is largely limited to animal and cellular studies. Evidence from human studies is needed.

Circulating microRNA as Biomarkers for Gestational Diabetes Mellitus-A Systematic Review and Meta-Analysis

Gestational diabetes mellitus (GDM) is a severe pregnancy complication for both the woman and the child. Women who suffer from GDM have a greater risk of developing Type 2 diabetes mellitus (T2DM) later in life. Identification of any potential biomarkers for the early prediction of gestational diabetes can help prevent the disease in women with a high risk. Studies show microRNA (miRNA) as a potential biomarker for the early discovery of GDM, but there is a lack of clarity as to which miRNAs are consistently altered in GDM. This study aimed to perform a systematic review and meta-analysis to investigate miRNAs associated with GDM by comparing GDM cases with normoglycemic controls. The systematic review was performed according to PRISMA guidelines with searches in PubMed, Web of Science, and ScienceDirect. The primary search resulted in a total of 849 articles, which were screened according to the prior established inclusion and exclusion criteria. Following the screening of articles, the review was based on the inclusion of 35 full-text articles, which were evaluated for risk of bias and estimates of quality, after which data were extracted and relative values for miRNAs were calculated. A meta-analysis was performed for the miRNA species investigated in three or more studies: MiR-29a, miR-330, miR-134, miR-132, miR-16, miR-223, miR-155, miR-122, miR-17, miR-103, miR-125, miR-210, and miR-222. While some miRNAs showed considerable between-study variability, miR-29a, miR-330, miR-134, miR-16, miR-223, and miR-17 showed significant overall upregulation in GDM, while circulating levels of miR-132 and miR-155 were decreased among GDM patients, suggesting further studies of these as biomarkers for early GDM discovery.

Placenta-Derived Extracellular Vesicles in Pregnancy Complications and Prospects on a Liquid Biopsy for Hemoglobin Bart's Disease

Extracellular vesicles (EVs) are nano-scaled vesicles released from all cell types into extracellular fluids and specifically contain signature molecules of the original cells and tissues, including the placenta. Placenta-derived EVs can be detected in maternal circulation at as early as six weeks of gestation, and their release can be triggered by the oxygen level and glucose concentration. Placental-associated complications such as preeclampsia, fetal growth restriction, and gestational diabetes have alterations in placenta-derived EVs in maternal plasma, and this can be used as a liquid biopsy for the diagnosis, prediction, and monitoring of such pregnancy complications. Alpha-thalassemia major ("homozygous alpha-thalassemia-1") or hemoglobin Bart's disease is the most severe form of thalassemia disease, and this condition is lethal for the fetus. Women with Bart's hydrops fetalis demonstrate signs of placental hypoxia and placentomegaly, thereby placenta-derived EVs provide an opportunity for a non-invasive liquid biopsy of this lethal condition. In this article, we introduced clinical features and current diagnostic markers of Bart's hydrops fetalis, extensively summarize the characteristics and biology of placenta-derived EVs, and discuss the challenges and opportunities of placenta-derived EVs as part of diagnostic tests for placental complications focusing on Bart's hydrop fetalis.

Circulating Extracellular Vesicles microRNAs Are Altered in Women Undergoing Preterm Birth

Preterm labor (PTL) and preterm premature rupture of membranes (PPROM) lead to high perinatal morbidity/mortality rates worldwide. Small extracellular vesicles (sEV) act in cell communication and contain microRNAs that may contribute to the pathogenesis of these complications. We aimed to compare the expression, in sEV from peripheral blood, of miRNAs between term and preterm pregnancies. This cross-sectional study included women who underwent PTL, PPROM, and term pregnancies, examined at the Botucatu Medical School Hospital, SP, Brazil. sEV were isolated from plasma. Western blot used to detect exosomal protein CD63 and nanoparticle tracking analysis were performed. The expression of 800 miRNAs was assessed by the nCounter Humanv3 miRNA Assay (NanoString). The miRNA expression and relative risk were determined. Samples from 31 women—15 preterm and 16 term—were included. miR-612 expression was increased in the preterm groups. miR-612 has been shown to increase apoptosis in tumor cells and to regulate the nuclear factor κB inflammatory pathway, processes involved in PTL/PPROM pathogenesis. miR-1253, miR-1283, miR378e, and miR-579-3p, all associated with cellular senescence, were downregulated in PPROM compared with term pregnancies. We conclude that miRNAs from circulating sEV are differentially expressed between term and preterm pregnancies and modulate genes in pathways that are relevant to PTL/PPROM pathogenesis.

Extracellular vesicles of immune cells; immunomodulatory impacts and therapeutic potentials

Extracellular vesicles (EVs) are a diverse collection of lipid bilayer-membrane-bound particles which are released from cells into the extracellular space and biologic fluids. In multicellular organisms, these vesicles facilitate the exchange of bioactive compounds such as RNA, DNA, proteins, various metabolites, and lipids between the cells. EVs are produced and released by almost all eukaryotic cells including immune cells and can have immunomodulating effects by either stimulation or suppression of their activities. This immune-modulating feature may provide a promising strategy for treating immune-mediated diseases such as cancer, neurodegenerative diseases, autoimmune disorders and graft-versus-host disease. Moreover, immune cell-derived EVs have received attention as potential biomarkers for being used as diagnostic tools and preventive strategies such as for developing vaccines. In this review, we focus on the EVs produced by different immune cell types, their effects on the immune system, and highlight their potential applications for immunotherapy.

Isolation of extracellular vesicles from bitch's amnion-derived cells culture and their CD59 expression: Preliminary results

Extracellular vesicles (EVs) are small spherical particles surrounded by a membrane with an unusual lipid composition and a striking cholesterol/phospholipidic ratio. About 2000 lipid and 3500 protein species were identified in EVs secreted by different cell sources. EVs mediate cell to cell communication in proximity to or distant from the cell of origin. In particular, it was suggested that they represent modulators of multiple processes during pregnancy. The aim of this study was to identify the presence of EVs in canine amnion-derived cells (ASCs) culture and the expression of CD 59 on their surface. Amniotic membrane was collected in PBS with antibiotics added from 2 bitches during elective caesarean section. Cells culture was prepared and EVs were isolated. EVs were used to evaluate CD59 expression by flow cytofluorimetry. We found that the majority of EVs expressed CD59. Our results could increase the knowledge about the complex mechanisms that regulate the pregnancy in the bitch.

Bacterial extracellular vesicles in the microbiome of first-pass meconium in newborn infants

BACKGROUND

Bacterial extracellular vesicles (EVs) are more likely to cross biological barriers than whole-cell bacteria. We previously observed EV-sized particles by electron microscopy in the first-pass meconium of newborn infants. We hypothesized that EVs may be of bacterial origin and represent a novel entity in the human microbiome during fetal and perinatal periods.

METHODS

We extracted EVs from first-pass meconium samples of 17 newborn infants and performed bacterial 16S rRNA gene sequencing of the vesicles. We compared the EV content from the meconium samples of infants based on the delivery mode, and in vaginal delivery samples, based on the usage of intrapartum antibiotics.

RESULTS

We found bacterial EVs in all first-pass meconium samples. All EV samples had bacterial RNA. Most of the phyla present in the samples were Firmicutes (62%), Actinobacteriota (18%), Proteobacteria (10%), and Bacteroidota (7.3%). The most abundant genera were Streptococcus (21%) and Staphylococcus (17%). The differences between the delivery mode and exposure to antibiotics were not statistically significant.

CONCLUSIONS

Bacterial EVs were present in the first-pass meconium of newborn infants. Bacterial EVs may represent an important novel feature of the gut microbiome during fetal and perinatal periods.

IMPACT

We show that bacterial extracellular vesicles are present in the microbiome of first-pass meconium in newborn infants. This is a novel finding. To our knowledge, this is the first study to report the presence of bacterial extracellular vesicles in the gut microbiome during fetal and perinatal periods. This finding is important because bacterial extracellular vesicles are more likely to cross biological barriers than whole-cell bacteria. Thus, the early gut microbiome may potentially interact with the host through bacterial EVs.

The role of extracellular vesicles in intercellular communication in human reproduction

Embryo-maternal cross-talk has emerged as a vitally important process for embryo development and implantation, which is driven by secreted factors and extracellular vesicles (EVs). The EV cargo of bioactive molecules significantly influences target cells and primes them for critical stages of reproductive biology, including embryo development, adhesion, and implantation. Recent research has suggested that EVs and their cargo represent a powerful non-invasive tool that can be leveraged to assess embryo and maternal tissue quality during assisted reproduction treatments. Here, we review the current scientific literature regarding the intercellular cross-talk between embryos and maternal tissues from fertilization to implantation, focusing on human biology and signaling mechanisms identified in animal models.

Microbiota-Associated HAF-EVs Regulate Monocytes by Triggering or Inhibiting Inflammasome Activation

In pregnancy, human amniotic fluid extracellular vesicles (HAF-EVs) exert anti-inflammatory effects on T cells and on monocytes, supporting their immunoregulatory roles. The specific mechanisms are still not completely defined. The aim of this study was to investigate the ability of HAF-EVs, isolated from pregnant women who underwent amniocentesis and purified by gradient ultracentrifugation, to affect inflammasome activation in the human monocytes. Proteomic studies revealed that HAF-EV samples expressed several immunoregulatory molecules as well as small amounts of endotoxin. Surprisingly, metagenomic analysis shows the presence of specific bacterial strain variants associated with HAF-EVs as potential sources of the endotoxin. Remarkably, we showed that a single treatment of THP-1 cells with HAF-EVs triggered inflammasome activation, whereas the same treatment followed by LPS and ATP sensitization prevented inflammasome activation, a pathway resembling monocyte refractories. A bioinformatics analysis of microbiota-HAF-EVs functional pathways confirmed the presence of enzymes for endotoxin biosynthesis as well as others associated with immunoregulatory functions. Overall, these data suggest that HAF-EVs could serve as a source of the isolation of a specific microbiota during early pregnancy. Moreover, HAF-EVs could act as a novel system to balance immune training and tolerance by modulating the inflammasome in monocytes or other cells.

Quantification of placental extracellular vesicles in different pregnancy status via single particle analysis method

BACKGROUND

The nano-sized, lipid bilayer-delimited placental extracellular vesicles (PEVs) released by the placenta are now regarded as important mediators involved in various physiological and pathological processes of pregnant women. The number and contents of PEVs are significantly altered in preeclampsia and are considered as potential biomarkers. However, the distribution pattern of PEVs in the maternal circulation in different pregnancy status is still unclear for the limitation of the traditional method with low sensitivity.

METHODS

In this work, we recruited 561 pregnant women with different pregnancy status and investigated the distribution pattern of PEVs in the maternal circulation based on a single extracellular vesicle analysis method and placental alkaline phosphatase (PLAP), a placenta-specific marker.

RESULTS

The concentration of PEVs in pregnant women increased with the progression of gestational age, while the ratio of PEVs decreased to about 10% in the third trimester. Surprisingly, the PLAP⁺ EVs also presented in the plasma of non-pregnant women and normal male about 5%. The change in the ratio of PEVs can reflect the pregnancy status and also had a better diagnostic value in severe preeclampsia (AUC = 0.7811).

CONCLUSIONS

Our study not only reveals the distribution pattern of PEVs, but also identifies the diagnostic potential of PEVs as biomarkers.

The exosome: a review of current therapeutic roles and capabilities in human reproduction

Exosomes are nano-vesicles (30-150 nm) which may be useful as therapeutic delivery vehicles and as diagnostic biomarkers. Exosomes are produced naturally within the human body and therefore are not prone to immunogenicity effects which would otherwise destroy unelicited foreign bodies. Clinically, they have been regarded as ideal candidates for applications relating to biomarker developments for the early detection of different diseases. Furthermore, exosomes may be of interest as potential drug delivery vehicles, which may improve factors such as bioavailability of loaded molecular cargo, side effect profiles, off-target effects, and pharmacokinetics of drug molecules. In this review, the therapeutic potential of exosomes and their use as clinical biomarkers for early diagnostics will be explored, alongside exosomes as therapeutic delivery vehicles. This review will evaluate techniques for cargo loading, and the capacity of loaded exosomes to improve various reproductive disease states. It becomes important, therefore, to consider factors such as loading efficiency, loading methods, cell viability, exosomal sources, exosome isolation, and the potential therapeutic benefits of exosomes. Issues related to targeted drug delivery will also be discussed. Finally, the variety of therapeutic cargo and the application of appropriate loading methods is explored, in the context of establishing clinical utility. Exosomes have more recently been widely accpeted as potential tools for disease diagnostics and the targeted delivery of certain therapeutic molecules-and in due time exosomes will be utilised more commonly within the clinical setting. Specifically, exosomal biomarkers can be identified and related to various detrimental conditions which occur during pregnancy. Considering, this review will explore the potential future of exosomes as both diagnostic tools and therapeutic delivery vehicles to treat related conditions, including the challenges which exist towards incorporating exosomes within the clinical environment to benefit patients.

Immunology of Pregnancy and Systemic Consequences

Pregnancy is an immunological paradox, with renowned Nobel Prize winning transplantation biologist Sir Peter Brian Medawar being the first to introduce this concept back in 1953. This concept considers how the maternal immune system can tolerate the developing fetus, which is 50% antigenically foreign to the uterus. There have been significant advances in our understanding of the immune system in regulating fertility, pregnancy and in complications of these, and what was once considered a paradox can be seen as a highly evolved system. Indeed, the complexity of the maternal-fetal interface along with our ever-advancing knowledge of immune cells and mediators means that we have a better understanding of these interactions, with gaps still present.  This chapter will summarise the key aspects of the role of the immune system at each stage of pregnancy and highlight the recent advances in our knowledge.

Mesenchymal stem cell-derived exosomes: The dawn of diabetic wound healing

Chronic wound healing has long been an unmet medical need in the field of wound repair, with diabetes being one of the major etiologies. Diabetic chronic wounds (DCWs), especially diabetic foot ulcers, are one of the most threatening chronic complications of diabetes. Although the treatment strategies, drugs, and dressings for DCWs have made great progress, they remain ineffective in some patients with refractory wounds. Stem cell-based therapies have achieved specific efficacy in various fields, with mesenchymal stem cells (MSCs) being the most widely used. Although MSCs have achieved good feedback in preclinical studies and clinical trials in the treatment of cutaneous wounds or other situations, the potential safety concerns associated with allogeneic/autologous stem cells and unknown long-term health effects need further attention and supervision. Recent studies have reported that stem cells mainly exert their trauma repair effects through paracrine secretion, and exosomes play an important role in intercellular communication as their main bioactive component. MSC-derived exosomes (MSC-Exos) inherit the powerful inflammation and immune modulation, angiogenesis, cell proliferation and migration promotion, oxidative stress alleviation, collagen remodeling imbalances regulation of their parental cells, and can avoid the potential risks of direct stem cell transplantation to a large extent, thus demonstrating promising performance as novel "cell-free" therapies in chronic wounds. This review aimed to elucidate the potential mechanism and update the progress of MSC-Exos in DCW healing, thereby providing new therapeutic directions for DCWs that are difficult to be cured using conventional therapy.

Extracellular vesicles in reproduction and pregnancy

Extracellular vesicles (EVs) are small, lipid-bound packages that are secreted by all cell types and have been implicated in many diseases, such as cancer and neurodegenerative disorders. Though limited, an exciting new area of EV research focuses on their role in the reproductive system and pregnancy. In males, EVs have been implicated in sperm production and maturation. In females, EVs play a vital role in maintaining reproductive organ homeostasis and pregnancy, including the regulation of folliculogenesis, ovulation, and embryo implantation. During the development and maintenance of a pregnancy, the placenta is the main form of communication between the mother and the developing fetus. To support the developing fetus, the placenta will act as numerous vital organs until birth, and release EVs into the maternal and fetal bloodstream. EVs play an important role in cell-to-cell communication and may mediate the pathophysiology of pregnancy-related disorders such as preeclampsia, gestational diabetes mellitus, preterm birth, and intrauterine growth restriction, and potentially serve as noninvasive biomarkers for these conditions. In addition, EVs may also mediate processes involved in both male and female infertility. Together, the EVs secreted by both the male and female reproductive tracts work to promote reproductive fertility and play vital roles in mediating maternal-fetal crosstalk and pregnancy maintenance.

Synergies of Extracellular Vesicles and Microchimerism in Promoting Immunotolerance During Pregnancy

The concept of biological identity has been traditionally a central issue in immunology. The assumption that entities foreign to a specific organism should be rejected by its immune system, while self-entities do not trigger an immune response is challenged by the expanded immunotolerance observed in pregnancy. To explain this "immunological paradox", as it was first called by Sir Peter Medawar, several mechanisms have been described in the last decades. Among them, the intentional transfer and retention of small amounts of cells between a mother and her child have gained back attention. These microchimeric cells contribute to expanding allotolerance in both organisms and enhancing genetic fitness, but they could also provoke aberrant alloimmune activation. Understanding the mechanisms used by microchimeric cells to exert their function in pregnancy has proven to be challenging as per definition they are extremely rare. Profiting from studies in the field of transplantation and cancer research, a synergistic effect of microchimerism and cellular communication based on the secretion of extracellular vesicles (EVs) has begun to be unveiled. EVs are already known to play a pivotal role in feto-maternal tolerance by transferring cargo from fetal to maternal immune cells to reshape their function. A further aspect of EVs is their function in antigen presentation either directly or on the surface of recipient cells. Here, we review the current understanding of microchimerism in the feto-maternal tolerance during human pregnancy and the potential role of EVs in mediating the allorecognition and tropism of microchimeric cells.

The role of extracellular vesicles in animal reproduction and diseases

Extracellular vesicles (EVs) are nanosized membrane-enclosed compartments that serve as messengers in cell-to-cell communication, both in normal physiology and in pathological conditions. EVs can transfer functional proteins and genetic information to alter the phenotype and function of recipient cells, which undergo different changes that positively affect their structural and functional integrity. Biological fluids are enriched with several subpopulations of EVs, including exosomes, microvesicles (MVs), and apoptotic bodies carrying several cargoes, such as lipids, proteins, and nucleic acids. EVs associated with the reproductive system are actively involved in the regulation of different physiological events, including gamete maturation, fertilization, and embryo and fetal development. EVs can influence follicle development, oocyte maturation, embryo production, and endometrial-conceptus communication. EVs loaded with cargoes are used to diagnose various diseases, including pregnancy disorders; however, these are dependent on the type of cell of origin and pathological characteristics. EV-derived microRNAs (miRNAs) and proteins in the placenta regulate inflammatory responses and trophoblast invasion through intercellular delivery in the placental microenvironment. This review presents evidence regarding the types of extracellular vesicles, and general aspects of isolation, purification, and characterization of EVs, particularly from various types of embryos. Further, we discuss EVs as mediators and messengers in reproductive biology, the effects of EVs on placentation and pregnancy disorders, the role of EVs in animal reproduction, in the male reproductive system, and mother and embryo cross-communication. In addition, we emphasize the role of microRNAs in embryo implantation and the role of EVs in reproductive and therapeutic medicine. Finally, we discuss the future perspectives of EVs in reproductive biology.

Single-cell atlas of peripheral blood mononuclear cells from pregnant women

Background

During pregnancy, mother–child interactions trigger a variety of subtle changes in the maternal body, which may be reflected in the status of peripheral blood mononuclear cells (PBMCs). Although these cells are easy to access and monitor, a PBMC atlas for pregnant women has not yet been constructed.

Methods

We applied single‐cell RNA sequencing (scRNA‐seq) to profile 198,356 PBMCs derived from 136 pregnant women (gestation weeks 6 to 40) and a control cohort. We also used scRNA‐seq data to establish a transcriptomic clock and thereby predicted the gestational age of normal pregnancy.

Results

We identified reconfiguration of the peripheral immune cell phenotype during pregnancy, including interferon‐stimulated gene upregulation, activation of RNA splicing‐related pathways and immune activity of cell subpopulations. We also developed a cell‐type‐specific model to predict gestational age of normal pregnancy.

Conclusions

We constructed a single‐cell atlas of PBMCs in pregnant women spanning the entire gestation period, which should help improve our understanding of PBMC composition turnover in pregnant women.

Single extracellular vesicle analysis in human amniotic fluid shows evidence of phenotype alterations in preeclampsia

Amniotic fluid surrounding the developing fetus is a complex biological fluid rich in metabolically active bio-factors. The presence of extracellular vesicles (EVs) in amniotic fluid has been mainly related to foetal urine. We here characterized EVs from term amniotic fluid in terms of surface marker expression using different orthogonal techniques. EVs appeared to be a heterogeneous population expressing markers of renal, placental, epithelial and stem cells. Moreover, we compared amniotic fluid EVs from normal pregnancies with those of preeclampsia, a hypertensive disorder affecting up to 8% of pregnancies worldwide. An increase of CD105 (endoglin) expressing EVs was observed in preeclamptic amniotic fluid by bead-based cytofluorimetric analysis, and further confirmed using a chip-based analysis. HLA-G, a typical placental marker, was not co-expressed by the majority of CD105+ EVs, in analogy with amniotic fluid stromal cell derived-EVs. At a functional level, preeclampsia-derived EVs, but not normal pregnancy EVs, showed an antiangiogenic effect, possibly due to the decoy effect of endoglin. Our results provide a characterization of term amniotic fluid-EVs, supporting their origin from foetal and placental cells. In preeclampsia, the observed antiangiogenic characteristics of amniotic fluid-EVs may reflect the hypoxic and antiangiogenic microenvironment and could possibly impact on the developing fetus or on the surrounding foetal membranes.

The implications of exosomes in pregnancy: emerging as new diagnostic markers and therapeutics targets

Extracellular vehicles (EVs) are a heterogeneous group of cell and membranous particles originating from different cell compartments. EVs participate in many essential physiological functions and mediate fetal-maternal communications. Exosomes are the smallest unit of EVs, which are delivered to the extracellular space. Exosomes can be released by the umbilical cord, placenta, amniotic fluid, and amniotic membranes and are involved in angiogenesis, endothelial cell migration, and embryo implantation. Also, various diseases such as gestational hypertension, gestational diabetes mellitus (GDM), preterm birth, and fetal growth restriction can be related to the content of placental exosomes during pregnancy. Due to exosomes' ability to transport signaling molecules and their effect on sperm function, they can also play a role in male and female infertility. In the new insight, exosomal miRNA can diagnose and treat infertilities disorders. In this review, we focused on the functions of exosomes during pregnancy. Video abstract.

Specific innate immune cells uptake fetal antigen and display homeostatic phenotypes in the maternal circulation

Pregnancy represents a period when the mother undergoes significant immunological changes to promote tolerance of the fetal semi-allograft. Such tolerance results from the exposure of the maternal immune system to fetal antigens (Ags), a process that has been widely investigated at the maternal-fetal interface and in the adjacent draining lymph nodes. However, the peripheral mechanisms of maternal-fetal crosstalk are poorly understood. Herein, we hypothesized that specific innate immune cells interact with fetal Ags in the maternal circulation. To test this hypothesis, a mouse model was utilized in which transgenic male mice expressing the chicken ovalbumin (OVA) Ag under the beta-actin promoter were allogeneically mated with wild-type females to allow for tracking of the fetal Ag. Fetal Ag-carrying Ly6G+ and F4/80+ cells were identified in the maternal circulation, where they were more abundant in the second half of pregnancy. Such innate immune cells displayed unique phenotypes: while Ly6G+ cells expressed high levels of MHC-II and CD80 together with low levels of pro-inflammatory cytokines, F4/80+ cells up-regulated the expression of CD86 as well as the anti-inflammatory cytokines IL-10 and TGF-β. In vitro studies using allogeneic GFP+ placental particles revealed that maternal peripheral Ly6G+ and F4/80+ cells phagocytose fetal Ags in mid and late murine pregnancy. Importantly, cytotrophoblast-derived particles were also engulfed in vitro by CD15+ and CD14+ cells from women in the second and third trimester, providing translational evidence that this process also occurs in humans. Collectively, this study demonstrates novel interactions between specific maternal circulating innate immune cells and fetal Ags, thereby shedding light on the systemic mechanisms of maternal-fetal crosstalk.

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.

Quantitative proteomic analysis of serum-purified exosomes identifies putative pre-eclampsia-associated biomarkers

BACKGROUND

The high incidence of pre-eclampsia, which affects 2-7% of all pregnancies, remains a major health concern. Detection of pre-eclampsia before the appearance of clinical symptoms is essential to allow early intervention, and would benefit from identification of plasma/serum biomarkers to help guide diagnosis and treatment. Liquid biopsy has emerged as a promising source of protein biomarkers that circumvents some of the inherent challenges of proteome-wide analysis of plasma/serum. In this respect, purified exosomes have the added benefit of being carriers of intercellular communication both in physiological and pathological conditions.

METHODS

We compared the protein complement of purified exosomes from three different collections of control and pre-eclamptic serum samples, obtained at the end of the second trimester of pregnancy and at delivery. We employed shotgun label-free proteomics to investigate differential protein expression, which was then validated by targeted proteomics.

RESULTS

We developed a purification method that yielded highly enriched exosome preparations. The presence of specific pregnancy protein markers suggested that a significant proportion of purified exosomes derived from tissues related to pregnancy. Quantitative proteomic analyses allowed us to identify 10, 114 and 98 differentially-regulated proteins in the three sample collections, with a high degree of concordance. Functional analysis suggested that these proteins participate in biological processes related to pre-eclampsia, including angiogenesis, inflammation and cell migration. The differential abundance of 66 proteins was validated by targeted proteomics. Finally, we studied the impact of the pre-eclampsia-associated exosomes in the proteome using an in vitro cellular model.

CONCLUSIONS

We have identified and validated differential exosomal proteins in liquid biopsy of pregnant women that open new possibilities for early detection of pre-eclampsia. Additionally, the functional impact of the proteome composition of purified pre-eclamptic exosomes in target cells provides new information to better understand changes in embryo-maternal interactions and, consequently, the pathogenesis of this disease.

Immunomodulatory Activity of Extracellular Vesicles of Kimchi-Derived Lactic Acid Bacteria (Leuconostoc mesenteroides, Latilactobacillus curvatus, and Lactiplantibacillus plantarum)

Lactic acid bacteria present in Kimchi, such as Leuconostoc mesenteroides (Lm), Latilactobacillus curvatus (Lc), and Lactiplantibacillus plantarum (Lp) produce extracellular vesicles (ECVs) that modulate immune responses. The ECVs of probiotic Kimchi bacteria are abbreviated as LmV, LcV, and LpV. Treatment of macrophages (RAW264.7) with ECVs (LmV, LcV, and LpV) increased the production of nitric oxide (NO), tumor necrosis factor (TNF)-α, and interleukin-6 (IL-6). Immunostimulatory effects exerted on the RAW264.7 cells were stronger after treatments with LmV and LcV than with LpV. Treatment of mice with LcV (1 mg/kg, orally) induced splenocyte proliferation and subsequent production of both NO and cytokines (INF-γ, TNF-α, IL-4, and IL-10). Furthermore, pre-treatment of macrophages and microglial cells with ECVs prior to LPS stimulation significantly attenuated the production of NO and pro-inflammatory cytokines (TNF-α, IL-1β, and IL-6). Therefore, ECVs (LmV, LcV, and LpV) prevent inflammatory responses in the LPS-stimulated microglial cells by blocking the extracellular signal-regulated kinase (Erk) and p38 signaling pathways. These results showed that LmV, LcV, and LpV from Kimchi probiotic bacteria safely exert immunomodulatory effects.

Non-Coding RNAs in Preeclampsia-Molecular Mechanisms and Diagnostic Potential

Preeclampsia (PE) is a leading cause of maternal and neonatal morbidity and mortality worldwide. Defects in trophoblast invasion, differentiation of extravillous trophoblasts and spiral artery remodeling are key factors in PE development. Currently there are no predictive biomarkers clinically available for PE. Recent technological advancements empowered transcriptome exploration and led to the discovery of numerous non-coding RNA species of which microRNAs (miRNAs) and long non-coding RNAs (lncRNAs) are the most investigated. They are implicated in the regulation of numerous cellular functions, and as such are being extensively explored as potential biomarkers for various diseases. Altered expression of numerous lncRNAs and miRNAs in placenta has been related to pathophysiological processes that occur in preeclampsia. In the following text we offer summary of the latest knowledge of the molecular mechanism by which lnRNAs and miRNAs (focusing on the chromosome 19 miRNA cluster (C19MC)) contribute to pathophysiology of PE development and their potential utility as biomarkers of PE, with special focus on sample selection and techniques for the quantification of lncRNAs and miRNAs in maternal circulation.

Assessment of Placental Extracellular Vesicles-Associated Fas Ligand and TNF-Related Apoptosis-Inducing Ligand in Pregnancies Complicated by Early and Late Onset Preeclampsia

Preeclampsia (PE) is a hypertensive disorder that affects 2-8% of pregnancies and is one of the main causes of fetal, neonatal, and maternal mortality and morbidity worldwide. Although PE etiology and pathophysiology remain unknown, there is evidence that the hyperactivation of maternal immunity cells against placental cells triggers trophoblast cell apoptosis and death. It has also been reported that placenta-derived extracellular vesicles (EV) carry Fas ligand (FasL) and Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) and trigger apoptosis in Jurkat T cells. This study aimed to quantify and compare FasL and TRAIL expression in EV derived from cultures of placenta explants from women with PE (early versus late) and women with uncomplicated pregnancies. Also, the study assessed EV capacity to induce apoptosis in Jurkat T cells. The authors isolated EV from placenta explant cultures, quantified FasL and TRAIL using ELISA, and analyzed EV apoptosis-inducing capability by flow cytometry. Results showed increased FasL and TRAIL in EV derived from placenta of women with PE, and increased EV apoptosis-inducing capability in Jurkat T cells. These results offer supporting evidence that EV FasL and TRAIL play a role in the pathophysiology of PE.

Extracellular Vesicles: An Important Biomarker in Recurrent Pregnancy Loss?

Recurrent pregnancy loss (RPL) has an estimated incidence of 1–3% of all couples. The etiology is considered to be multifactorial. Extracellular vesicles (EVs) take part in numerous different physiological processes and their contents show the originating cell and pathophysiological states in different diseases. In pregnancy disorders, changes can be seen in the composition, bioactivity and concentration of placental and non-placental EVs. RPL patients have an increased risk of pregnancy complications. The aim of this prospective study was to examine whether measuring different specific EV markers in plasma before and during pregnancy could be used as predictors of pregnancy loss (PL) in women with RPL. Thirty-one RPL patients were included in this study; 25 had a live birth (LB group) and six had a new PL (PL group). Five blood samples were obtained, one before achieved pregnancy and the others in gestational week 6, 8, 10 and 16. Moreover, some of the patients received intravenous immunoglobulin (IVIG) infusions as part of treatment, and it was also examined whether this treatment influenced the EV levels. Seventeen EV markers specific for the immune system, coagulation, placenta and hypoxia were analyzed in the samples with EV Array, a method able to capture small EVs by using an antibody panel targeting membrane proteins. Comparing the LB and PL groups, one EV marker, CD9, showed a significant increase from before pregnancy to gestational week 6 in the PL group. The changes in the other 16 markers were nonsignificant. One case of late-onset PL showed steeply increasing levels, with sudden decrease after gestational week 10 in nine of 17 markers. Moreover, there was an overall increase of all 17 markers after IVIG treatment in the LB group, which was significant in 15 of the markers. Whether increases in EVs positive for CD9 characterize RPL patients who subsequently miscarry should be investigated in future larger studies.

Systemic Characterization of Novel Immune Cell Phenotypes in Recurrent Pregnancy Loss

Recurrent pregnancy loss (RPL) is a disturbing disease in women, and 50% of RPL is reported to be associated with immune dysfunction. Most previous studies of RPL focused mainly on the relationship between RPL and either T cells or natural killer (NK) cells in peripheral blood and the decidua; few studies presented the systemic profiles of the peripheral immune cell subsets in RPL women. Herein, we simultaneously detected 63 immune cell phenotypes in the peripheral blood from nonpregnant women (NPW), women with a history of normal pregnancy (NP) and women with a history of RPL (RPL) by multi-parameter flow cytometry. The results demonstrated that the percentages of naïve CD4⁺ T cells, central memory CD4⁺ T cells, naïve CD8⁺ T cells, mature NK cells, Vδ1⁺ T cells and the ratio of Vδ1⁺ T cells/Vδ2⁺ T cells were significantly higher in the RPL group than those in the NPW and NP groups, whereas the percentages of terminal differentiated CD4⁺ T cells, effective memory CD4⁺ T cells, immature NK cells and Vδ2⁺ T cells were significantly lower in the RPL group than those in the NPW and NP groups. Interestingly, we found that peripheral T helper (T_PH) cells were more abundant in the NPW group than in the NP and RPL groups. In addition, we also determined the 5^th percentile lower limit and 95^th percentile upper limit of the significantly changed immunological parameters based on the files of the NPW group. Taken together, this is the first study to simultaneously characterize the multiple immune cell subsets in the peripheral blood at a relatively large scale in RPL, which might provide a global readout of the immune status for clinicians to identify clinically-relevant immune disorders and guide them to make clear and individualized advice and treatment plans.

Exosomal integrins and their influence on pancreatic cancer progression and metastasis

As one of the most lethal and untreatable types of cancer so far, pancreatic cancer is not benefitting from advancements in research. Despite all the efforts, this malignancy is still very difficult to diagnose in time, resistant to treatments, and prone to relapses. The appearance of metastasis-notoriously difficult to fight and a signal of unfortunate prognosis-is the event most dreaded by every cancer patient, especially by those with pancreatic cancer. Strategies for early detection and treatment of metastases are limited, and new action plans are desperately awaited. Recently, the importance of cell-secreted vesicles, or exosomes, in cell-cell communication and, particularly, their key role in promoting pathological conditions, such as infectious diseases and cancer, have attracted the attention of the scientific community. The discovery of some exosome membrane components, such as adhesion receptors and integrins, and their ability to influence cancer cell functions and metastasis progression, has added some important understanding of the metastatic process and will hopefully open the door to the development of new tools for identifying and targeting metastases. The aim of this review is to discuss the role played by integrins in exosomal-mediated pancreatic cancer progression and metastasis.