TGF-β1 inhibits human trophoblast cell invasion by upregulating kisspeptin expression through ERK1/2 but not SMAD signaling pathway

TGFβ signalling: a nexus between inflammation, placental health and preeclampsia throughout pregnancy

BACKGROUND

The placenta is a unique and pivotal organ in reproduction, controlling crucial growth and cell differentiation processes that ensure a successful pregnancy. Placental development is a tightly regulated and dynamic process, in which the transforming growth factor beta (TGFβ) superfamily plays a central role. This family of pleiotropic growth factors is heavily involved in regulating various aspects of reproductive biology, particularly in trophoblast differentiation during the first trimester of pregnancy. TGFβ signalling precisely regulates trophoblast invasion and the cell transition from cytotrophoblasts to extravillous trophoblasts, which is an epithelial-to-mesenchymal transition-like process. Later in pregnancy, TGFβ signalling ensures proper vascularization and angiogenesis in placental endothelial cells. Beyond its role in trophoblasts and endothelial cells, TGFβ signalling contributes to the polarization and function of placental and decidual macrophages by promoting maternal tolerance of the semi-allogeneic foetus. Disturbances in early placental development have been associated with several pregnancy complications, including preeclampsia (PE) which is one of the severe complications. Emerging evidence suggests that TGFβ is involved in the pathogenesis of PE, thereby offering a potential target for intervention in the human placenta.

OBJECTIVE AND RATIONALE

This comprehensive review aims to explore and elucidate the roles of the major members of the TGFβ superfamily, including TGFβs, bone morphogenetic proteins (BMPs), activins, inhibins, nodals, and growth differentiation factors (GDFs), in the context of placental development and function. The review focusses on their interactions within the major cell types of the placenta, namely trophoblasts, endothelial cells, and immune cells, in both normal pregnancies and pregnancies complicated by PE throughout pregnancy.

SEARCH METHODS

A literature search was carried out using PubMed and Google Scholar, searching terms: 'TGF signalling preeclampsia', 'pregnancy TGF signalling', 'preeclampsia tgfβ', 'preeclampsia bmp', 'preeclampsia gdf', 'preeclampsia activin', 'endoglin preeclampsia', 'endoglin pregnancy', 'tgfβ signalling pregnancy', 'bmp signalling pregnancy', 'gdf signalling pregnancy', 'activin signalling pregnancy', 'Hofbauer cell tgfβ signalling', 'placental macrophages tgfβ', 'endothelial cells tgfβ', 'endothelium tgfβ signalling', 'trophoblast invasion tgfβ signalling', 'trophoblast invasion Smad', 'trophoblast invasion bmp', 'trophoblast invasion tgfβ', 'tgfβ preeclampsia', 'tgfβ placental development', 'TGFβ placental function', 'endothelial dysfunction preeclampsia tgfβ signalling', 'vascular remodelling placenta TGFβ', 'inflammation pregnancy tgfβ', 'immune response pregnancy tgfβ', 'immune tolerance pregnancy tgfβ', 'TGFβ pregnancy NK cells', 'bmp pregnancy NK cells', 'bmp pregnancy tregs', 'tgfβ pregnancy tregs', 'TGFβ placenta NK cells', 'TGFβ placenta tregs', 'NK cells preeclampsia', 'Tregs preeclampsia'. Only articles published in English until 2023 were used.

OUTCOMES

A comprehensive understanding of TGFβ signalling and its role in regulating interconnected cell functions of the main placental cell types provides valuable insights into the processes essential for successful placental development and growth of the foetus during pregnancy. By orchestrating trophoblast invasion, vascularization, immune tolerance, and tissue remodelling, TGFβ ligands contribute to the proper functioning of a healthy maternal-foetal interface. However, dysregulation of TGFβ signalling has been implicated in the pathogenesis of PE, where the shallow trophoblast invasion, defective vascular remodelling, decreased uteroplacental perfusion, and endothelial cell and immune dysfunction observed in PE, are all affected by an altered TGFβ signalling.

WIDER IMPLICATIONS

The dysregulation of TGFβ signalling in PE has important implications for research and clinical practice. Further investigation is required to understand the underlying mechanisms, including the role of different ligands and their regulation under pathophysiological conditions, in order to discover new therapeutic targets. Distinguishing between clinically manifested subtypes of PE and studying TGFβ signalling in different placental cell types holistically is an important first step. To put this knowledge into practice, pre-clinical animal models combined with new technologies are needed. This may also lead to improved human research models and identify potential therapeutic targets, ultimately improving outcomes for affected pregnancies and reducing the burden of PE.

Mendelian randomization supports genetic liability to hospitalization for COVID-19 as a risk factor of pre-eclampsia

Background

Pre-eclampsia and eclampsia are among the major threats to pregnant women and fetuses, but they can be mitigated by prevention and early screening. Existing observational research presents conflicting evidence regarding the causal effects of coronavirus disease 2019 (COVID-19) on pre-eclampsia risk. Through Mendelian randomization (MR), this study aims to investigate the causal effect of three COVID-19 severity phenotypes on the risk of pre-eclampsia and eclampsia to provide more rigorous evidence.

Methods

Two-sample MR was utilized to examine causal effects. Summary-level data from genome-wide association studies (GWAS) of individuals of European ancestry were acquired from the GWAS catalog and FinnGen databases. Single-nucleotide polymorphisms associated with COVID-19 traits at p < 5 × -8 were obtained and pruned for linkage disequilibrium to generate instrumental variables for COVID-19. Inverse variance weighted estimates were used as the primary MR results, with weighted median and MR-Egger as auxiliary analyses. The robustness of the MR findings was also evaluated through sensitivity analyses. Bonferroni correction was applied to primary results, with a p < 0.0083 considered significant evidence and a p within 0.083-0.05 considered suggestive evidence.

Results

Critical ill COVID-19 [defined as hospitalization for COVID-19 with either a death outcome or respiratory support, OR (95% CI): 1.17 (1.03-1.33), p = 0.020] and hospitalized COVID-19 [defined as hospitalization for COVID-19, OR (95% CI): 1.10 (1.01-1.19), p = 0.026] demonstrated suggestive causal effects on pre-eclampsia, while general severe acute respiratory syndrome coronavirus 2 infection did not exhibit a significant causal effect on pre-eclampsia. None of the three COVID-19 severity phenotypes exhibited a significant causal effect on eclampsia.

Conclusions

Our investigation demonstrates a suggestive causal effect of genetic susceptibility to critical ill COVID-19 and hospitalized COVID-19 on pre-eclampsia. The COVID-19 severity exhibited a suggestive positive dose-response relationship with the risk of pre-eclampsia. Augmented attention should be paid to pregnant women hospitalized for COVID-19, especially those needing respiratory support.

Effects of calcitriol upon TGF-βs and their receptors in trophoblast cells

Calcitriol levels increase during pregnancy, contributing to the hormonal and immunological balance, but its deficiency has been associated with problems during this period. Meanwhile, transforming growth factors-β (TGF-βs) play an important role in the maintenance of fetal-maternal immune tolerance; however, exacerbated concentrations of this growth factor are associated with complicated pregnancies. Therefore, we studied the effects of calcitriol on TGF-βs and their receptors in trophoblast cells. Term placentas from uncomplicated pregnancies after cesarean sections were used for cell cultures. Basal gene expression and the effect of calcitriol upon TGF-β1, TGF-β2, TGF-β3, and their receptors TGF-βR1 and TGF-βR2 were assessed using real-time PCR from trophoblast cells. The presence of TGF-β1, 2, 3, and TGF-βR1 were evaluated by immunofluorescence, and the protein abundance and secretion of TGF-β1 were assessed by Western blot and ELISA, respectively. Basal gene expression of TGF-β1 in trophoblast from term placentas was higher than TGF-β2 and TGF-β3, while TGF-βR2 was higher than TGF-βR1. The presence and cellular localization of TGF-β1, 2, 3, and TGF-βR1 were detected in the cytoplasm of syncytiotrophoblast, with TGF-β1 showing the highest intensity. Calcitriol significantly inhibited gene expression of TGF-β1, TGF-β2, and TGF-βR1. Likewise, calcitriol decreased the secretion and abundance of TGF-β1. In conclusion, results indicate that calcitriol is a regulator of TGF-βs in cultured trophoblast cells from term placentas and therefore may be an important player in the development of healthy pregnancies.

TET2-mediated DNA hydroxymethylation of TGFB1 is related to selective intrauterine growth restriction in monochorionic twin pregnancies

INTRODUCTION

Selective intrauterine growth restriction (sIUGR), which specifically occurs in monochorionic (MC) twins, usually has a poor prognosis and the underlying mechanisms are not well understood. It is an ideal model for exploring epigenetic-modified mechanisms for fetal development in MCDA twins due to eliminating the interference of different heritable backgrounds and intrauterine environments among individuals.

METHODS

The levels of ten-eleven translocation 2 (TET2) and its upstream and downstream targets miR-29b-3p and transforming growth factor beta 1 (TGFB1) were determined using RT‒qPCR, western blotting, and immunohistochemistry. Using TET2 overexpression and knockdown methods, we investigated the role of TET2 in trophoblast functions. The regulatory relationships among TET2, miR-29b-3p, and TGFB1 were explored by cell migration assay, invasion assay, apoptotic ratio assays, Western blot, hMeDIP-qPCR and dual-luciferase assay.

RESULTS

A consistent upregulation of TET2 and TGFB1 was observed in the smaller placental shares compared to the larger placental shares in sIUGR. Gain-of-function studies of TET2 in trophoblasts showed decreased cell invasion and increased apoptosis, whereas loss-of-function studies of TET2 rescued this effect. Mechanistic studies revealed that miR-29b-3p and TGFB1 were the upstream factor and downstream target of TET2, respectively. Furthermore, miR-29b-3p/TET2/TGFB1-smad was identified as a unique axis that regulates trophoblast invasion, migration, and apoptosis in a DNA hydroxymethylation-dependent manner.

DISCUSSION

We elucidated the functional roles of TET2 and DNA hydroxymethylation in trophoblasts and identified a novel DNA regulatory mechanism, providing a basis for further exploration of DNA epigenetic regulatory patterns in sIUGR.

The Role of TGF-β during Pregnancy and Pregnancy Complications

Transforming growth factor beta (TGF-β), a multifunctional cytokine, is one of the most important inflammatory cytokines closely related to pregnancy. It plays significant roles in hormone secretion, placental development, and embryonic growth during pregnancy. TGF-β is implicated in embryo implantation and inhibits the invasion of extraepithelial trophoblast cells. It also moderates the mother-fetus interaction by adjusting the secretion pattern of immunomodulatory factors in the placenta, consequently influencing the mother's immune cells. The TGF-β family regulates the development of the nervous, respiratory, and cardiovascular systems by regulating gene expression. Furthermore, TGF-β has been associated with various pregnancy complications. An increase in TGF-β levels can induce the occurrences of pre-eclampsia and gestational diabetes mellitus, while a decrease can lead to recurrent miscarriage due to the interference of the immune tolerance environment. This review focuses on the role of TGF-β in embryo implantation and development, providing new insights for the clinical prevention and treatment of pregnancy complications.

Molecular interaction of metastasis suppressor genes and tumor microenvironment in breast cancer

Breast cancer (BC) is a leading cause of cancer-related deaths in women worldwide where the process of metastasis is a major contributor to the mortality associated with this disease. Metastasis suppressor genes are a group of genes that play a crucial role in preventing or inhibiting the spread of cancer cells. They suppress the metastasis process by inhibiting colonization and by inducing dormancy. These genes function by regulating various cellular processes in the tumor microenvironment (TME), such as cell adhesion, invasion, migration, and angiogenesis. Dysregulation of metastasis suppressor genes can lead to the acquisition of an invasive and metastatic phenotype and lead to poor prognostic outcomes. The components of the TME generally play a necessary in the metastasis progression of tumor cells. This review has identified and elaborated on the role of a few metastatic suppressors associated with the TME that have been shown to inhibit metastasis in BC by different mechanisms, such as blocking certain cell signaling molecules involved in cancer cell migration, invasion, enhancing immune surveillance of cancer cells, and promoting the formation of a protective extracellular matrix (ECM). Understanding the interaction of metastatic suppressor genes and the components of TME has important implications for the development of novel therapeutic strategies to target the metastatic cascade. Targeting these genes or their downstream signaling pathways offers a promising approach to inhibiting the spread of cancer cells and improves patient outcomes.

Decidual cells and decidualization in the carnivoran endotheliochorial placenta

Decidualization is considered a distinctive feature of eutherian pregnancy, and has appeared during evolution along with the development of invasive forms of placentation, as the endotheliochorial placenta. Although decidualization is not massive in carnivores, as it is in most species developing hemochorial placentas, isolated or grouped cells regarded as decidual have been documented and characterized, mainly in bitches and queens. For the majority of the remaining species of the order, data in the bibliography are fragmentary. In this article, general morphological aspects of decidual stromal cells (DSCs), their time of appearance and lasting, data about the expression of cytoskeletal proteins and molecules considered as markers of decidualization were reviewed. From the data reviewed, it follows that carnivoran DSCs take part either in the secretion of progesterone, prostaglandins, relaxin, among other substances, or at least in the signaling pathways triggered by them. Beyond their physiological roles, some of those molecules are already being used, or are yet under study, for the non-invasive endocrine monitoring and reproductive control of domestic and wild carnivores. Only insulin-like growth factor binding protein 1, among the main decidual markers, has been undoubtedly demonstrated in both species. Laminin, on the contrary, was found only in feline DSCs, and prolactin was preliminary reported in dogs and cats. Prolactin receptor, on the other hand, was found in both species. While canine DSCs are the only placental cell type expressing the nuclear progesterone receptor (PGR), that receptor has not been demonstrated neither in feline DSCs, nor in any other cell in the queen placenta, although the use of PGR blockers leads to abortion. Against this background, and from the data gathered so far, it is unquestionable that DSCs in carnivorans do play a pivotal role in placental development and health. The knowledge about placental physiology is critical for medical care and breeding management, primarily in domestic carnivores; it is also absolutely crucial for a conservation approach in the management of endangered carnivore species.

Kisspeptin and kisspeptin receptor immunoreactivity in euploid and aneuploid choriodecidual tissues of recurrent pregnancy losses

OBJECTIVE

To study choriodecidual immunoreactivity of kisspeptin (KISS1) and its receptor (KISS1R) in recurrent pregnancy loss (RPL) due to aneuploidy (AnE) and unexplained (UE) RPL in comparison to control elective abortions (EAbs).

DESIGN

This is a case-control study.

SETTING

Tertiary care facility and affiliated research institute.

PATIENT(S)

Patients with either UE RPL (n = 10) or RPL due to AnE (n = 10) vs. a control group of patients who underwent EAb (n = 10).

INTERVENTION(S)

Immunohistochemistry of archived choriodecidual tissue samples.

MAIN OUTCOME MEASURE(S)

Histoscores of KISS1 and KISS1R immunoreactivity in the syncytiotrophoblast (SyT), cytotrophoblast (CyT), decidual glands (DeGs), and decidual stroma (DeS) across the 3 study groups.

RESULT(S)

There was no difference in both maternal and gestational ages among the 3 groups. Kisspeptin immunoreactivity was similar in the SyT, CyT, DeGs, and DeS of all groups. Similarly, KISS1R expression was not different in the DeGs or DeS among all study groups. In addition, there was no difference in KISS1R immunoreactivity in the SyTs and CyTs between patients with RPL due to AnE and those with UE RPL. However, KISS1R was significantly lower in the SyT and CyT of patients with RPL due to AnE and UE RPL than in those who underwent EAb.

CONCLUSION(S)

The expression of KISS1R is lower in the chorionic tissues of euploid (unexplained) and aneuploid RPLs than in the control group. The current results broaden our understanding of the role played by KISS1 and KISS1R in early placentation. Further investigation is necessary to determine whether KISS1 activity is the cause or a sequel of defective placentation.

The Update Immune-Regulatory Role of Pro- and Anti-Inflammatory Cytokines in Recurrent Pregnancy Losses

Recurrent pregnancy losses (RPL) is a common reproductive disorder with various underlying etiologies. In recent years, rapid progress has been made in exploring the immunological mechanisms for RPL. A propensity toward Th2 over Th1 and regulatory T (Treg) over Th17 immune responses may be advantageous for reproductive success. In women with RPL and animals prone to abortion, an inordinate expression of cytokines associated with implantation and early embryo development is present in the endometrium or decidua secreted from immune and non-immune cells. Hence, an adverse cytokine milieu at the maternal-fetal interface assaults immunological tolerance, leading to fetal rejection. Similar to T cells, NK cells can be categorized based on the characteristics of cytokines they secrete. Decidual NK (dNK) cells of RPL patients exhibited an increased NK1/NK2 ratio (IFN-γ/IL-4 producing NK cell ratios), leading to pro-inflammatory cytokine milieu and increased NK cell cytotoxicity. Genetic polymorphism may be the underlying etiologies for Th1 and Th17 propensity since it alters cytokine production. In addition, various hormones participate in cytokine regulations, including progesterone and estrogen, controlling cytokine balance in favor of the Th2 type. Consequently, the intricate regulation of cytokines and hormones may prevent the RPL of immune etiologies. Local or systemic administration of cytokines or their antagonists might help maintain adequate cytokine milieu, favoring Th2 over Th1 response or Treg over Th17 immune response in women with RPL. Herein, we provided an updated comprehensive review regarding the immune-regulatory role of pro- and anti-inflammatory cytokines in RPL. Understanding the roles of cytokines involved in RPL might significantly advance the early diagnosis, monitoring, and treatment of RPL.

The Role of Kisspeptin in the Pathogenesis of Pregnancy Complications: A Narrative Review

Kisspeptins are the family of neuropeptide products of the KISS-1 gene that exert the biological action by binding with the G-protein coupled receptor 54 (GPR54), also known as the KISS-1 receptor. The kisspeptin level dramatically increases during pregnancy, and the placenta is supposed to be its primary source. The role of kisspeptin has already been widely studied in hypogonadotropic hypogonadism, fertility, puberty disorders, and insulin resistance-related conditions, including type 2 diabetes mellitus, polycystic ovary syndrome, and obesity. Gestational diabetes mellitus (GDM), preeclampsia (PE), preterm birth, fetal growth restriction (FGR), or spontaneous abortion affected 2 to 20% of pregnancies worldwide. Their occurrence is associated with numerous short and long-term consequences for mothers and newborns; hence, novel, non-invasive predictors of their development are intensively investigated. The study aims to present a comprehensive review emphasizing the role of kisspeptin in the most common pregnancy-related disorders and neonatal outcomes. The decreased level of kisspeptin is observed in women with GDM, FGR, and a high risk of spontaneous abortion. Nevertheless, there are still many inconsistencies in kisspeptin concentration in pregnancies with preterm birth or PE. Further research is needed to determine the usefulness of kisspeptin as an early marker of gestational and neonatal complications.

Kisspeptin treatment improves fetal-placental development and blocks placental oxidative damage caused by maternal hypothyroidism in an experimental rat model

Maternal hypothyroidism is associated with fetal growth restriction, placental dysfunction, and reduced kisspeptin/Kiss1R at the maternal-fetal interface. Kisspeptin affects trophoblastic migration and has antioxidant and immunomodulatory activities. This study aimed to evaluate the therapeutic potential of kisspeptin in the fetal-placental dysfunction of hypothyroid Wistar rats. Hypothyroidism was induced by daily administration of propylthiouracil. Kisspeptin-10 (Kp-10) treatment was performed every other day or daily beginning on day 8 of gestation. Feto-placental development, placental histomorphometry, and expression levels of growth factors (VEGF, PLGF, IGF1, IGF2, and GLUT1), hormonal (Dio2) and inflammatory mediators (TNFα, IL10, and IL6), markers of hypoxia (HIF1α) and oxidative damage (8-OHdG), antioxidant enzymes (SOD1, Cat, and GPx1), and endoplasmic reticulum stress mediators (ATF4, GRP78, and CHOP) were evaluated on day 18 of gestation. Daily treatment with Kp-10 increased free T3 and T4 levels and improved fetal weight. Both treatments reestablished the glycogen cell population in the junctional zone. Daily treatment with Kp-10 increased the gene expression levels of Plgf, Igf1, and Glut1 in the placenta of hypothyroid animals, in addition to blocking the increase in 8-OHdG and increasing protein and/or mRNA expression levels of SOD1, Cat, and GPx1. Daily treatment with Kp-10 did not alter the higher protein expression levels of VEGF, HIF1α, IL10, GRP78, and CHOP caused by hypothyroidism in the junctional zone compared to control, nor the lower expression of Dio2 caused by hypothyroidism. However, in the labyrinth zone, this treatment restored the expression of VEGF and IL10 and reduced the GRP78 and CHOP immunostaining. These findings demonstrate that daily treatment with Kp-10 improves fetal development and placental morphology in hypothyroid rats, blocks placental oxidative damage, and increases the expression of growth factors and antioxidant enzymes in the placenta.