The Maternal-Fetal Interface in Small-for-Gestational-Age Pregnancies Is Associated With a Reduced Quantity of Human Decidual NK Cells With Weaker Functional Ability

To boldly go where no microRNAs have gone before: spaceflight impact on risk for small-for-gestational-age infants

In the era of renewed space exploration, comprehending the effects of the space environment on human health, particularly for deep space missions, is crucial. While extensive research exists on the impacts of spaceflight, there is a gap regarding female reproductive risks. We hypothesize that space stressors could have enduring effects on female health, potentially increasing risks for future pregnancies upon return to Earth, particularly related to small-for-gestational-age (SGA) fetuses. To address this, we identify a shared microRNA (miRNA) signature between SGA and the space environment, conserved across humans and mice. These miRNAs target genes and pathways relevant to diseases and development. Employing a machine learning approach, we identify potential FDA-approved drugs to mitigate these risks, including estrogen and progesterone receptor antagonists, vitamin D receptor antagonists, and DNA polymerase inhibitors. This study underscores potential pregnancy-related health risks for female astronauts and proposes pharmaceutical interventions to counteract the impact of space travel on female health.

Correlation Between Maternal-Fetus Interface and Placenta-Mediated Complications

Pregnancy is a highly regulated biological phenomenon that involves the development of a semi-allogeneic fetus inside the uterus of the mother. The maternal-fetal interface is a critical junction where communication takes place between the fetal and maternal immune systems, which determine the outcome of the pregnancy. The interface is composed of the decidua and placenta. The main cells present at the maternal-fetal interface include invading trophoblasts, maternal immune cells, and decidual stromal cells. Although maternal tolerance is crucial for maintaining a successful pregnancy, the role of the placenta in pregnancy is also important. Dysregulation of the placenta leads to various placenta-mediated complications, such as preeclampsia, intrauterine growth restriction, and placental abruption. Although the exact mechanism involving these complications is unclear, research has elucidated various factors involved in these pregnancy disorders. This review aimed to provide a summary of the maternal-fetal interface and immune mechanisms involved in placenta-mediated complications.

[Experimental Study on the Characteristic Changes of the Immunological Microenvironment at the Maternal-Fetal Interface in IVF-ET Pregnancy]

Objective

To investigate the characteristic functional changes of the decidual natural killer (NK) cells and γδ T cells, two immunocytes in the decidua, at the maternal-fetal interface in in vitro fertilization-embryo transfer (IVF-ET) pregnancy.

Methods

Decidual samples were collected from 12 women of natural pregnancy (NP) and 32 women of IVF-ET pregnancy, who were enrolled in the NP group and the IVF-ET group, respectively. Then part of the decidual samples were paraffin-embedded for HE staining and immunofluorescence staining, while the rest of the samples were digested and Percoll was used for isolating decidual immunocytes (DICs) by gradient centrifugation. Flow cytometry was used to determine the cell counts of decidual NK cells and γδ T cells and the expression levels of their surface activation markers, CD69 and NKG2D in the NP and the IVF-ET groups. In addition, the expression levels of IFN-γ, TNF-α, IL-17A, and IL-10, the intracellular cytokines, and granzyme B, perforin, and granulysin, the cytolytic granules, were measured. The characteristic changes in the relevant immunological indicators were compared and analyzed.

Results

HE staining of the tissue specimens showed that the typical structure of decidua was observed, and that lymphocytes were enriched in the decidua. Immunofluorescence staining showed that the percentage of decidual NK (dNK) cells in nucleated cells of the IVF-ET group was significantly lower than that of the NP group ( P<0.05). Flow cytometry analysis of DICs showed that, compared with those of the NP group, the percentage of dNK cells of the IVF-ET group was decreased ( P<0.05) and the expression levels of IL-10 and perforin were significantly decreased in the IVF-ET group ( P<0.05). However, there was no significant difference in the decidual γδ T (dγδT) cell count between the two groups. The expression of IL-10, IL-17A, and perforin was downregulated in the IVF-ET group ( P<0.05). There was no significant difference in the expression of IFN-γ, TNF-α, granzyme B, and granulysin, the cellular function indicators ( P>0.05).

Conclusion

The dNK cell count and the secretion of some intracellular cytokines of dNK and dγδT cells of women of IVF-ET pregnancy decreased to some degree, which suggests that certain changes may have taken place in the immunological microenvironment at the maternal-fetal interface. The specific effect of these changes on pregnancy outcomes needs further investigation.

Functional prominence of natural killer cells and natural killer T cells in pregnancy and infertility: A comprehensive review and update

During pregnancy, complicated connections are formed between a mother and a fetus. In a successful pregnancy, the maternal-fetal interface is affected by dynamic changes, and the fetus is protected against the mother's immune system. Natural killer (NK) cells are one of the immune system cells in the female reproductive system that play an essential role in the physiology of pregnancy. NK cells not only exist in peripheral blood (PB) but also can exist in the decidua. Studies have suggested multiple roles for these cells, including decidualization, control of trophoblast growth and invasion, embryo acceptance and maintenance by the mother, and facilitation of placental development during pregnancy. Natural killer T (NKT) cells are another group of NK cells that play a crucial role in the maintenance of pregnancy and regulation of the immune system during pregnancy. Studies show that NK and NKT cells are not only effective in maintaining pregnancy but also can be involved in infertility-related diseases. This review focuses on NK and NKT cells biology and provides a detailed description of the functions of these cells in implantation, placentation, and immune tolerance during pregnancy and their role in pregnancy complications.

Early Pregnancy Human Decidua Gamma/Delta T Cells Exhibit Tissue Resident and Specific Functional Characteristics

A successful pregnancy is a complicated process that builds upon two aspects of the maternal immune system that need to be balanced. As one of the indispensable groups of immune cell at the maternal-fetal interface, the decidual gamma/delta (γδ) T cells have attracted research attention in normal pregnancy and miscarriage. However, the role of γδ T cells in fetal growth remains poorly understood. Here we found that the γδ T cell population resident in decidua during early pregnancy was enriched and secreted growth factors including growth differentiation factor 15 (GDF15) and bone morphogenetic protein 1 (BMP1). A diminution in such growth factors may impair fetal development and result in fetal growth restriction. We also observed that early decidual γδ T cells exhibited stronger cytokine-secretion characteristics, but that their cytotoxic actions against A549 cells were weaker, compared with γδ T cells in peripheral blood mononuclear cells (PBMCs). In addition, the functional abilities of early decidual γδ T cells in promoting trophoblast cell proliferation, migration, invasion, and tube formation were also significantly more robust than in γδ T cells of PBMCs. These findings highlight the importance of γδ T cells in fetal growth and maternal immunotolerance during pregnancy, and show that they differ from γδ T cells in PBMCs. We thus recommend additional investigation in this research area to further elucidate a role for γδ T cells in pregnancy.

Up-regulation of TGFBI and TGFB2 in the plasma of gestational diabetes mellitus patients and its clinical significance

BACKGROUND

Gestational diabetes mellitus (GDM) reflects a deficiency in the relative need for insulin during pregnancy, as well as temporary metabolic stress in the placenta and fetus. Our study aimed to research the potential diagnostic value of transforming growth factor-beta-induced protein ig-h3 (TGFBI) and transforming growth factor beta-2 proprotein (TGFB2) for GDM patients.

METHODS

Online database Gene Expression Omnibus (GEO) was used to screen for different expressed genes (DEGs) associated with GDM. Meanwhile, KEGG and GO were used to analyze the molecular functions as well as pathways of enriched DEGs. One hundred ten pregnant women diagnosed with GDM and 110 healthy controls were enrolled, of whose placenta and fasting venous blood samples were collected. mRNA expression levels were determined by real-time quantitative polymerase chain reaction (RT-qPCR), and fasting blood glucose (FBG) was measured by the clinical lab of hospital. Furthermore, receiver operating characteristics curve (ROC) analysis was performed to evaluate the sensitivity and specificity of detection indexed in the placenta and plasma of GDM patients. Finally, Pearson and Spearman analysis was used for the correlation analysis.

RESULTS

After GEO data analysis, TGFBI and TGFB2 were identified as the most significantly up-regulated genes of GDM. TGFBI and TGFB2 expressions in placenta and plasma samples of GDM patients were in line with bioinformatic analysis. Meanwhile, the area under the curve (AUC) of TGFBI in the placenta and plasma for the diagnosis of GDM were 0.8783 (95% CI, 0.8281 to 0.9284) and 0.7832 (95% CI, 0.7215 to 0.8449) while for TGFB2 were 0.9225 (95% CI, 0.8829 to 0.9621) and 0.8961 (95% CI, 0.8526 to 0.9396). Besides, levels of TGFBI along with TGFB2 in the placenta were positively correlated with that in the plasma of GDM patients. Furthermore, both TGFBI and TGFB2 expressions in the plasma were positively correlated with FBG levels of the GDM patients.

CONCLUSIONS

TGFBI and TGFB2 were up-regulated in the placenta and plasma of GDM patients, and TGFBI and TGFB2 in the plasma are potent to be diagnostic markers for the GDM.

miRNAs in decidual NK cells: regulators worthy of attention during pregnancy

The critical immune effectors, including T, B, and natural killer (NK) cells, dendritic cells, and macrophages participate in regulating immune responses during pregnancy. Among these immune cells, decidual NK (dNK) cells are involved in key placental development processes at the maternal-fetal interface, such as uterine spiral artery remodeling, trophoblast invasion, and decidualization. Mechanistically, dNK cells significantly influence pregnancy outcome by secreting cytokines, chemokines, and angiogenic mediators and by their interactions with trophoblasts and other decidual cells. MicroRNAs (miRNAs) are small non-coding RNA molecules that participate in the initiation and progression of human diseases. Although the functions of circulating miRNAs in pathological mechanism has been extensively studied, the regulatory roles of miRNAs in NK cells, especially in dNK cells, have been rarely reported. In this review, we analyze the effects of miRNA regulations of dNK cell functions on the immune system during gestation. We discuss aberrant expressions of certain miRNAs in dNK cells that may lead to pathological consequences, such as recurrent pregnancy loss (RPL). Interestingly, miRNA expression patterns are also different between dNK cells and peripheral NK (pNK) cells, and pNK cells in the first- and third-trimester of gestation. The dysregulation of miRNA plays a pivotal regulatory role in driving immune functions of dNK and pNK cells. Further understanding of the molecular mechanisms of miRNAs in dNK cells may provide new insights into the development of therapeutics to prevent pregnancy failure.

A Brief Analysis of Tissue-Resident NK Cells in Pregnancy and Endometrial Diseases: The Importance of Pharmacologic Modulation

NK cells are lymphocytes involved in the innate and adaptative immune response. These cells are located in peripheral blood and tissues with ample functions, from immune vigilant to tolerogenic reactions. In the endometrium, NK cell populations vary depending on age, hormones, and inflammation. When pregnancy occurs, tissue-resident NK cells and conventional NK cells are recruited to protect the fetus, a tolerogenic response. On the contrary, in the inflamed endometrium, various inflammatory cells down-regulate NK tolerance and impair embryo implantation. Therefore, NK cells’ pharmacological modulation is difficult to achieve. Several strategies have been used, from progesterone, lipid emulsions to steroids; the success has not been as expected. However, new therapeutic approaches have been proposed to decrease the endometrial inflammatory burden and increase pregnancy success based on understanding NK cell physiology.

Continuous activation of polymorphonuclear myeloid-derived suppressor cells during pregnancy is critical for fetal development

The maternal immune system is vital in maintaining immunotolerance to the semiallogeneic fetus for a successful pregnancy. Although studies have shown that myeloid-derived suppressor cells (MDSCs) play an important role in maintaining feto-maternal tolerance, little is known about the role of MDSCs in pregnancies with intrauterine growth retardation (IUGR). Here, we reported that the activation of polymorphonuclear myeloid-derived suppressor cells (PMN-MDSCs) during pregnancy was closely associated with fetal growth. In humans, class E scavenger receptor 1 (SR-E1), a distinct marker for human PMN-MDSCs, was used to investigate PMN-MDSC function during pregnancy. Continuous activation of SR-E1⁺ PMN-MDSCs was observed in all stages of pregnancy, accompanied by high cellular levels of ROS and arginase-1 activity, mediated through STAT6 signaling. However, SR-E1⁺ PMN-MDSCs in pregnancies with IUGR showed significantly lower suppressive activity, lower arginase-1 activity and ROS levels, and decreased STAT6 phosphorylation level, which were accompanied by an increase in inflammatory factors, compared with those in normal pregnancies. Moreover, the population of SR-E1⁺ PMN-MDSCs was negatively correlated with the adverse outcomes of newborns from pregnancies with IUGR. In mice, decreases in cell population, suppressive activity, target expression levels, and STAT6 phosphorylation levels were also observed in the pregnancies with IUGR compared with the normal pregnancies, which were rescued by the adoptive transfer of PMN-MDSCs from pregnant mice. Interestingly, the growth-promoting factors (GPFs) secreted by placental PMN-MDSCs in both humans and mice play a vital role in fetal development. These findings collectively support that PMN-MDSCs have another new role in pregnancy, which can improve adverse neonatal outcomes.