Interplay between neutrophils and trophoblast cells conditions trophoblast function and triggers vascular transformation signals

Effects of bacterial extracellular vesicles derived from oral and gastrointestinal pathogens on systemic diseases

Oral microbiota and gastrointestinal microbiota, the two largest microbiomes in the human body, are closely correlated and frequently interact through the oral-gut axis. Recent research has focused on the roles of these microbiomes in human health and diseases. Under normal conditions, probiotics and commensal bacteria can positively impact health. However, altered physiological states may induce dysbiosis, increasing the risk of pathogen colonization. Studies suggest that oral and gastrointestinal pathogens contribute not only to localized diseases at their respective colonized sites but also to the progression of systemic diseases. However, the mechanisms by which bacteria at these local sites are involved in systemic diseases remain elusive. In response to this gap, the focus has shifted to bacterial extracellular vesicles (BEVs), which act as mediators of communication between the microbiota and the host. Numerous studies have reported the targeted delivery of bacterial pathogenic substances from the oral cavity and the gastrointestinal tract to distant organs via BEVs. These pathogenic components subsequently elicit specific cellular responses in target organs, thereby mediating the progression of systemic diseases. This review aims to elucidate the extensive microbial communication via the oral-gut axis, summarize the types and biogenesis mechanisms of BEVs, and highlight the translocation pathways of oral and gastrointestinal BEVs in vivo, as well as the impacts of pathogens-derived BEVs on systemic diseases.

Myeloperoxidase enhances the migration and invasion of human choriocarcinoma JEG-3 cells

Myeloperoxidase (MPO) is one of the most abundant proteins in neutrophil granules. It catalyzes the production of reactive oxygen species, which are important in inflammation and immune defense. MPO also binds to several proteins, lipids, and DNA to alter their function. MPO is present at the feto-maternal interface during pregnancy, where neutrophils are abundant. In this study, we determined the effect of MPO on JEG-3 human choriocarcinoma cells as a model of extravillous trophoblasts (EVTs) during early pregnancy. We found that MPO was internalized by JEG-3 cells and localized to the cytoplasm and nuclei. MPO internalization and activity enhanced JEG-3 cell migration and invasion, whereas this effect was impaired by pre-treating cells with heparin, to block cellular uptake, and MPO-activity inhibitor 4-ABAH. This study identifies a novel mechanism for the effect of MPO on EVT function during normal pregnancy and suggests a potential role of MPO in abnormal pregnancies.

Extracellular Vesicles of Porphyromonas gingivalis Disrupt Trophoblast Cell Interaction with Vascular and Immune Cells in an In Vitro Model of Early Placentation

Extracellular vesicles released by the primary pathogen of periodontal disease Porphyromonas gingivalis (Pg), referred to as outer membrane vesicles (OMVs), have been associated with the pathogenesis of systemic diseases like cardiovascular disease, rheumatoid arthritis, and Alzheimer's disease. A pathogenic role for Pg by disrupting placental homeostasis was proposed in the association between periodontal disease and adverse pregnancy outcomes. On the basis that trophoblast-derived factors modulate endothelial and immune cell profiles in normal pregnancy and the scarce presence of Pg in placenta, we hypothesized that OMVs from Pg affect trophoblast cell phenotype, impairing trophoblast-endothelium and trophoblast-neutrophil interactions. By means of in vitro designs with first-trimester human trophoblast cells, endothelial cells, and freshly isolated neutrophils, we showed that Pg OMVs are internalized by trophoblast cells and modulate the activity and expression of functional markers. Trophoblast cells primed with Pg OMVs enhanced neutrophil chemoattraction and lost their anti-inflammatory effect. In addition, reduced migration with enhanced adhesion of monocytes was found in endothelial cells upon incubation with the media from trophoblast cells pretreated with Pg OMVs. Taken together, the results support a pathogenic role of Pg OMVs at early stages of pregnancy and placentation through disruption of trophoblast contribution to vascular transformation and immune homeostasis maintenance.

Neutrophils in pregnancy: New insights into innate and adaptive immune regulation

The immunology of pregnancy has been the focus of many studies to better understand how the mother is able to tolerate the presence of a semi-allogeneic fetus. Far from the initial view of pregnancy as a state of immunosuppression, successful fetal development from implantation to birth is now known to be under the control of an intricate balance of immune cells. The balance between pro-inflammatory functions used to promote embryo implantation and placental development and immunosuppressive activity to maintain maternal tolerance of the fetus is an immunological phenotype unique to pregnancy, which is dependent on the time of gestation. Neutrophils are one of a host of innate immune cells detected at the maternal-fetal interface, but very little is known of their function. In this review, we explore the emerging functions of neutrophils during pregnancy and their interactions with and regulation of T cells, a key adaptive immune cell population essential for the establishment of fetal-maternal tolerance.

In Vitro Identification and Isolation of Human Neutrophil Extracellular Traps

Neutrophils release web like-structures known as neutrophil extracellular traps (NETs) that ensnare and kill microorganisms. These networks are constituted of a DNA scaffold with associated antimicrobial proteins, which are released to the extracellular space as an effective mechanism to fight against invading microorganisms. In parallel with this beneficial role to avoid microbial dissemination and wall off infections, accumulating evidence supports that under certain circumstances, NETs can exert deleterious effects in inflammatory, autoimmune, and thrombotic pathologies. Research on NET properties and their role in pathophysiological processes is a rapidly evolving and expanding field. Here, we describe a combination of methods to achieve a successful in vitro NET visualization, semiquantification, and isolation.

Decidual factors and vasoactive intestinal peptide guide monocytes to higher migration, efferocytosis and wound healing in term human pregnancy

AIM

To explore the functional profile of circulating monocytes and decidual macrophages at term human pregnancy and their contribution to tissue repair upon stimulation ex vivo with decidual factors and the vasoactive intestinal peptide (VIP).

METHODS

Peripheral blood monocytes were isolated from pregnant and non-pregnant volunteers and tested in vitro with decidual explants from term placenta and VIP. The effect of VIP on decidual explants and the effect of its conditioned media on monocytes or decidual macrophages isolated by magnetic beads was carried out by RT-qPCR and ELISA for cytokines expression and release. Migration assays were performed in transwell systems. Efferocytosis was assessed in monocytes or decidual macrophages with CFSE-labelled autologous apoptotic neutrophils and quantified by flow cytometry. Monocyte and decidual macrophages wound healing capacity was evaluated using human endometrial stromal cell monolayers. Immunohistochemistry was performed in serial tissue sections of different placentas.

RESULTS

VIP is expressed in the villi as well as in trophoblast giant cells distributed within the decidua of term placenta. VIP induced the expression of antiinflmammatory markers and monocyte chemoattractant CCL2 and CCL3 in decidual tissues. Monocytes presented higher migration towards decidual explants than CD4 and CD8 cells. VIP-conditioned monocytes displayed an enhanced efferocytosis and wound healing capacity comparable to that of decidual macrophages. Moreover limited efferocytosis of pregnant women monocytes was restored by VIP-induced decidual factors.

CONCLUSION

Results show the conditioning of monocytes by decidual factors and VIP to sustain processes required for tissue repair and homeostasis maintenance in term placenta.

The Role of Neutrophils and Their Extracellular Traps in the Synergy of Pre-eclampsia and HIV Infection

PURPOSE OF THE REVIEW

In our innate immune system, neutrophils are the first cells to sense signals of infection and to proceed to kill the invading pathogen. This is mediated by their production of neutrophil extracellular traps (NETS) to entrap pathogenic micro-organisms, preventing their amplification and dissemination. Pre-eclampsia (PE) is the leading cause of global maternal mortality, yet to date, there is no cure nor a gold-standard diagnostic strategy. The purpose of this review is to discover the role of neutrophils in PE as early identification markers. Additionally, this review aims to explore the role of neutrophils in HIV-infected pregnancies with PE as a source of synergy.

RECENT FINDINGS

Recent findings demonstrate an elevation of neutrophils and neutrophil extracellular traps (NETs) in PE placentae. This is due to their activation by excessive release of syncytiotrophoblast microparticles (STBM). There is also an elevation of NETs in HIV-infected placentae-where histone H3 entraps HIV by binding to its glycoprotein envelope. Additionally, histones H1 and H2A inhibit HIV infection. It is interesting to note that women with both PE and HIV infection have supressed NETs. This review focuses on the role of neutrophils in the synergy of PE and HIV infection. It is plausible that the deregulation of NETs in the synergy of pre-eclamptic HIV-infected women is strategic for the entrapment of the HIV-1 virus. Finally, it is plausible that neutrophils and NETS may act as early biomarkers of PE development. Graphical abstract.