Trophoblast expression of the minor histocompatibility antigen HA-1 is regulated by oxygen and is increased in placentas from preeclamptic women

Cellular mechanisms linking to outdoor and indoor air pollution damage during pregnancy

Pregnancies are a critical window period for environmental influences over the mother and the offspring. There is a growing body of evidence associating indoor and outdoor air pollution exposure to adverse pregnancy outcomes such as preterm birth and hypertensive disorders of pregnancy. Particulate matter (PM) could trigger oxi-inflammation and could also reach the placenta leading to placental damage with fetal consequences. The combination of strategies such as risk assessment, advise about risks of environmental exposures to pregnant women, together with nutritional strategies and digital solutions to monitor air quality can be effective in mitigating the effects of air pollution during pregnancy.

The role of maternal T cell and macrophage activation in preterm birth: Cause or consequence?

The role of the immune system in term (TL) and preterm labor (PTL) is unknown. Despite the fact that globally, PTL remains the most important cause of childhood mortality. Infection, typically of the fetal membranes, termed chorioamnionitis, is the best-understood driver of PTL, but the mechanisms underpinning other causes, including idiopathic and stretch-induced PTL, are unclear, but may well involve activation of the maternal immune system. The final common pathway of placental dysfunction, fetal membrane rupture, cervical dilation and uterine contractions are highly complex processes. At term, choriodecidual rather than myometrial inflammation is thought to drive the onset of labor and similar findings are present in different types of PTL including idiopathic PTL. Although accumulated data has confirmed an association between the immune response and preterm birth, there is yet a need to understand if this response is an initiator or a consequence of tissue-level dysregulation. This review focuses on the potential role of macrophages and T cells in innate and adaptive immunity relevant to preterm birth in humans and animal models.

Preliminary RNA-Seq Analysis of Long Non-Coding RNAs Expressed in Human Term Placenta

Development of particular structures and proper functioning of the placenta are under the influence of sophisticated pathways, controlled by the expression of substantial genes that are additionally regulated by long non-coding RNAs (lncRNAs). To date, the expression profile of lncRNA in human term placenta has not been fully established. This study was conducted to characterize the lncRNA expression profile in human term placenta and to verify whether there are differences in the transcriptomic profile between the sex of the fetus and pregnancy multiplicity. RNA-Seq data were used to profile, quantify, and classify lncRNAs in human term placenta. The applied methodology enabled detection of the expression of 4463 isoforms from 2899 annotated lncRNA loci, plus 990 putative lncRNA transcripts from 607 intergenic regions. Those placentally expressed lncRNAs displayed features such as shorter transcript length, longer exon length, fewer exons, and lower expression levels compared to messenger RNAs (mRNAs). Among all placental transcripts, 175,268 were classified as mRNAs and 15,819 as lncRNAs, and 56,727 variants were discovered within unannotated regions. Five differentially expressed lncRNAs (HAND2-AS1, XIST, RP1-97J1.2, AC010084.1, TTTY15) were identified by a sex-bias comparison. Splicing events were detected within 37 genes and 4 lncRNA loci. Functional analysis of cis-related potential targets for lncRNAs identified 2021 enriched genes. It is presumed that the obtained data will expand the current knowledge of lncRNAs in placenta and human non-coding catalogs, making them more contemporary and specific.

Foetoplacental communication via extracellular vesicles in normal pregnancy and preeclampsia

Intercellular communication is a critical process in biological mechanisms. During pregnancy foetoplacental tissues release a heterogeneous group of extracellular vesicles (EVs) that include exosomes, microvesicles, apoptotic bodies, and syncytial nuclear aggregates. These vesicles contain a complex cargo (proteins, DNA, mRNA transcripts, microRNAs, noncoding RNA, lipids, and other molecules) that actively participate in the maternal-foetal communication by modulating different processes during gestation for a successful foetal development. Each stage of human gestation is marked by events such as immunomodulation, proliferation, invasion, migration, and differentiation, among others, requiring EVs-mediated signalling to be nearby or distant target cells. Furthermore, EVs also associate with pregnancy pathologies such as preeclampsia and intrauterine growth restriction. This review addresses the role of EVs in human foetomaternal communication in normal pregnancy and preeclampsia.

The minor histocompatibility antigen 1 (HMHA1)/ArhGAP45 is a RacGAP and a novel regulator of endothelial integrity

Endothelial cells line the vasculature and act as gatekeepers that control the passage of plasma, macromolecules and cells from the circulation to the interstitial space. Dysfunction of the endothelial barrier can lead to uncontrolled leak or edema. Vascular leakage is a hallmark of a range of diseases and despite its large impact no specialized therapies are available to prevent or reduce it. RhoGTPases are known key regulators of cellular behavior that are directly involved in the regulation of the endothelial barrier. We recently performed a comprehensive analysis of the effect of all RhoGTPases and their regulators on basal endothelial integrity. In addition to novel positive regulators of endothelial barrier function, we also identified novel negative regulators, of which the ArhGAP45 (also known as HMHA1) was the most significant. We now demonstrate that ArhGAP45 acts as a Rac-GAP (GTPase-Activating Protein) in endothelial cells, which explains its negative effect on endothelial barrier function. Silencing ArhGAP45 not only promotes basal endothelial barrier function, but also increases cellular surface area and induces sprout formation in a 3D-fibrin matrix. Our data further shows that loss of ArhGAP45 promotes migration and shear stress adaptation. In conclusion, we identify ArhGAP45 (HMHA1) as a novel regulator, which contributes to the fine-tuning of the regulation of basal endothelial integrity.

Trophoblast Glycoprotein (TPGB/5T4) in Human Placenta: Expression, Regulation, and Presence in Extracellular Microvesicles and Exosomes

BACKGROUND

Many parallels exist between growth and development of the placenta and that of cancer. One parallel is shared expression of antigens that may have functional importance and may be recognized by the immune system. Here, we characterize expression and regulation of one such antigen, Trophoblast glycoprotein (TPGB; also called 5T4), in the placenta across gestation, in placentas of preeclamptic (PE) pregnancies, and in purified microvesicles and exosomes.

METHODS

Trophoblast glycoprotein expression was analyzed by real-time reverse transcription-polymerase chain reaction (RT-PCR), Western blot, and immunohistochemistry. Regulation of 5T4 in cytotrophoblast cells was examined under either differentiating conditions of epidermal growth factor or under varying oxygen conditions. Microvesicles and exosomes were purified from supernatant of cultured and perfused placentas.

RESULTS

Trophoblast glycoprotein expression was prominent at the microvillus surface of syncytiotrophoblast and on the extravillous trophoblast cells, with minimal expression in undifferentiated cytotrophoblasts and normal tissues. Trophoblast glycoprotein expression was elevated in malignant tumors. In cytotrophoblasts, 5T4 was induced by in vitro differentiation, and its messenger RNA (mRNA) was increased under conditions of low oxygen. PE placentas expressed higher 5T4 mRNA than matched control placentas. Trophoblast glycoprotein was prominent within shed placental microvesicles and exosomes.

CONCLUSION

Given the potential functional and known immunological importance of 5T4 in cancer, these studies reveal a class of proteins that may influence placental development and/or sensitize the maternal immune system. In extravillous trophoblasts, 5T4 may function in epithelial-to-mesenchymal transition during placentation. The role of syncytiotrophoblast 5T4 is unknown, but its abundance in shed syncytial vesicles may signify route of sensitization of the maternal immune system.

Update of syncytiotrophoblast derived extracellular vesicles in normal pregnancy and preeclampsia

The release of extracellular vesicles (EV) by the syncytiotrophoblast (STB) may be an important mechanism by which the placenta signals to the mother. STB derived EV (STBEV) are comprised predominantly of exosomes (50-150nm) and microvesicles (100-1000nm) that contain bioactive mediators such as proteins, nucleic acids and lipids. They, along with larger syncytial nuclear aggregates are released by the STB into the maternal circulation throughout gestation in normal pregnancy where they appear to have an immunoregulatory role, inhibiting T cell and NK cell responses. In pre-eclampsia (PE) STBEV are released in significantly increased numbers and have pro-inflammatory, anti-angiogenic and procoagulant activity, implicating them in the maternal systemic inflammation, endothelial dysfunction and activation of the clotting system which typifies the disorder. Research has focused on understanding the biological significance of STBEV by measuring their size and repertoire of molecules carried and how they differ in normal pregnancy and PE, using techniques such as Nanoparticle Tracking Analysis, flow cytometry and mass spectrometry. We have also found alterations in STBEV surface glycans associated with PE. The goal is to better understand the role STBEV play in normal pregnancy and PE and whether they are potential biomarkers of placental pathology and therapeutic targets in PE.