Kisspeptins and the placenta: regulation of trophoblast invasion

Adipose Kiss1 controls aerobic exercise-related adaptive responses in adipose tissue energy homeostasis

Kisspeptin signaling regulates energy homeostasis. Adiposity is the principal source and receiver of peripheral Kisspeptin, and adipose Kiss1 metastasis suppressor (Kiss1) gene expression is stimulated by exercise. However, whether the adipose Kiss1 gene regulates energy homeostasis and plays a role in adaptive alterations during prolonged exercise remains unknown. Here, we investigated the role of Kiss1 role in mice and adipose tissues and the adaptive changes it induces after exercise, using adipose-specific Kiss1 knockout (Kiss1adipoq-/-) and adeno-associated virus-induced adipose tissue Kiss1-overexpressing (Kiss1adipoq over) mice. We found that adipose-derived kisspeptin signal regulates lipid and glucose homeostasis to maintain systemic energy homeostasis, but in a sex-dependent manner, with more pronounced metabolic changes in female mice. Kiss1 regulated adaptive alterations of genes and proteins in tricarboxylic acid (TCA) cycle and oxidative phosphorylation (OxPhos) pathways in female gWAT following prolonged aerobic exercise. We could further show that adipose Kiss1 deficiency leads to reduced peroxisome proliferator-activated receptor gamma co-activator 1 alpha (PGC-1α) protein content of soleus muscle and maximum oxygen uptake (VO2 max) of female mice after prolonged exercise. Therefore, adipose Kisspeptin may be a novel adipokine that increases organ sensitivity to glucose, lipids, and oxygen following exercise.

Maternal obesity and offspring neurodevelopment are associated with hypoxic gene expression in term human placenta

One third of women in the United States are affected by obesity during pregnancy. Maternal obesity (MO) is associated with an increased risk of neurodevelopmental and metabolic disorders in the offspring. The placenta, located at the maternal-fetal interface, is a key organ determining fetal development and likely contributes to programming of long-term offspring health. We profiled the term placental transcriptome in humans (pre-pregnancy BMI 35+ [MO condition] or 18.5-25 [lean condition]) using single-nucleus RNA-seq to compare expression profiles in MO versus lean conditions, and to reveal potential mechanisms underlying offspring disease risk. We recovered 62,864 nuclei of high quality from 10 samples each from the maternal-facing and fetal-facing sides of the placenta. On both sides in several cell types, MO was associated with upregulation of hypoxia response genes. On the maternal-facing side only, hypoxia gene expression was associated with offspring neurodevelopmental measures, in Gen3G, an independent pregnancy cohort with bulk placental tissue RNA-seq. We leveraged Gen3G to determine genes that correlated with impaired neurodevelopment and found these genes to be most highly expressed in extravillous trophoblasts (EVTs). EVTs further showed the strongest correlation between neurodevelopment impairment gene scores (NDIGSs) and the hypoxia gene score. We reanalyzed gene expression of cultured EVTs, and found increased NDIGSs associated with exposure to hypoxia. Among EVTs, accounting for the hypoxia gene score attenuated 44% of the association between BMI and NDIGSs. These data suggest that hypoxia in EVTs may be a key process in the neurodevelopmental programming of fetal exposure to MO.

Kisspeptin Regulates Cell Invasion and Migration in Endometrial Cancer

Kisspeptin (a product of the KISS1 gene and its receptor) plays an important role in obstetrics, gynecology, and cancer cell metastasis and behavior. In hypothalamic-pituitary-gonadal axis and placentation, Kisspeptin/Kisspeptin receptor affects hormone release and represses trophoblast invasion into maternal deciduae. Endometrial cancer is one of the common gynecological cancers and is usually accompanied by metastasis, the risk factor that causes death. Recently, research has demonstrated that Kisspeptin/Kisspeptin receptor expression in aggressive-stage endometrial cancer tissues. However, the detailed mechanism of Kisspeptin/Kisspeptin receptor in regulating the motility of endometrial cancers is not well understood. In this study, we use endometrial cancer cell lines RL95-2, Ishikawa, HEC-1-A, and HEC-1-B as models to explore the molecular mechanism of Kisspeptin on cell motility. First, we discovered that Kisspeptin/Kisspeptin receptor was expressed in endometrial cancer cells, and Kisspeptin significantly regulated the migration and invasion of endometrial cancer cells. Furthermore, we explored the epithelial-mesenchymal transition marker expression and the underlying signals were regulated on Kisspeptin treatment. In conclusion, we suggest that Kisspeptin regulates endometrial cancer cell motility via FAK and Src expression and the ERK1/2, N-Cadherin, E-Cadherin, beta-Catenin, Twist, and matrix metalloproteinase signaling pathways. We expect these molecules could be candidates for the development of new approaches and therapeutic targets.

The Emerging Therapeutic Potential of Kisspeptin and Neurokinin B

Kisspeptin (KP) and neurokinin B (NKB) are neuropeptides that govern the reproductive endocrine axis through regulating hypothalamic gonadotropin-releasing hormone (GnRH) neuronal activity and pulsatile GnRH secretion. Their critical role in reproductive health was first identified after inactivating variants in genes encoding for KP or NKB signaling were shown to result in congenital hypogonadotropic hypogonadism and a failure of pubertal development. Over the past 2 decades since their discovery, a wealth of evidence from both basic and translational research has laid the foundation for potential therapeutic applications. Beyond KP's function in the hypothalamus, it is also expressed in the placenta, liver, pancreas, adipose tissue, bone, and limbic regions, giving rise to several avenues of research for use in the diagnosis and treatment of pregnancy, metabolic, liver, bone, and behavioral disorders. The role played by NKB in stimulating the hypothalamic thermoregulatory center to mediate menopausal hot flashes has led to the development of medications that antagonize its action as a novel nonsteroidal therapeutic agent for this indication. Furthermore, the ability of NKB antagonism to partially suppress (but not abolish) the reproductive endocrine axis has supported its potential use for the treatment of various reproductive disorders including polycystic ovary syndrome, uterine fibroids, and endometriosis. This review will provide a comprehensive up-to-date overview of the preclinical and clinical data that have paved the way for the development of diagnostic and therapeutic applications of KP and NKB.

KISS1 and Kisspeptins Detection in Cell Lines

KISS1 belongs to the family of metastasis suppressor genes. However, its role is not limited to blocking cancer metastasis. KISS1 and its by-product kisspeptins (KP) are important players in regulating the reproductive axis in different species and have new roles in controlling physiological balance and social behaviors. These diverse functions point to KISS1 as a potential therapeutic molecule. Here we describe a methodology to detect KISS1 and KP from cell lysate and conditioned media in cell lines. This will serve as a critical tool to study KISS1 processing in KP.

SCAP contributes to embryonic angiogenesis by negatively regulating KISS-1 expression in mice

Sterol regulatory element-binding protein (SREBP) cleavage-activating protein (SCAP) is indispensable in organ development because it maintains intracellular cholesterol homeostasis. The vessel is not widely conceived of as a cholesterol-sensitive tissue, so the specific role of SCAP in angiogenesis has not been paid attention to. As an important component of the vascular mesoderm, vascular smooth muscle cells (VSMCs) are widely involved in each step of angiogenesis. Here, we report for the first time that VSMC-specific ablation of SCAP inhibits VSMC proliferation and migration, interacting with endothelial cells (ECs), and finally causes defective embryonic angiogenesis in mice. Mechanistically, we demonstrated that SCAP ablation in VSMCs leads to the upregulation of KISS-1 protein, consequently resulting in suppressed activation of the MAPK/ERK signaling pathway and downregulation of matrix metalloproteinase 9 (MMP9) and vascular endothelial-derived growth factor (VEGF) expression to prevent angiogenesis. Importantly, we found that SCAP promotes the cleavage and nuclear translocation of SREBP2, which acts as a negative transcription regulator, regulating KISS-1 expression. Our findings suggest that SCAP contributes to embryonic angiogenesis by negatively regulating KISS-1 expression in mice and provide a new point of view for therapeutic targets of vascular development.

KISS1 metastasis suppressor in tumor dormancy: a potential therapeutic target for metastatic cancers?

Present therapeutic approaches do not effectively target metastatic cancers, often limited by their inability to eliminate already-seeded non-proliferative, growth-arrested, or therapy-resistant tumor cells. Devising effective approaches targeting dormant tumor cells has been a focus of cancer clinicians for decades. However, progress has been limited due to limited understanding of the tumor dormancy process. Studies on tumor dormancy have picked up pace and have resulted in the identification of several regulators. This review focuses on KISS1, a metastasis suppressor gene that suppresses metastasis by keeping tumor cells in a state of dormancy at ectopic sites. The review explores mechanistic insights of KISS1 and discusses its potential application as a therapeutic against metastatic cancers by eliminating quiescent cells or inducing long-term dormancy in tumor cells.

Follicular Fluid Growth Factors and Interleukin Profiling as Potential Predictors of IVF Outcomes

Growth hormone (GH) has gained attention as an anti-aging compound enhancing oocyte quality. In fact, GH is known to activate intrafollicular metabolic events for oocyte maturation. Insulin growth factor I (IGF1) is another ovarian growth factor that mediates the FSH and GH actions. Cytokines could also increase IVF outcomes. Indeed, IL-6 is a pleiotropic cytokine with multiple cellular effects that can vary based on the physiological environment. IL-6 may also play an important role in follicular development (Yang et al., J Assist Reprod Genet, 2020, 37 (5), 1171–1176). Clinical studies have been performed to explore the potential role of IL-6 in human oocyte maturation and subsequent embryonic development. To date, the answers are not conclusive. During peri-implantation, many cytokines balances are regulated like pro-inflammatory and anti-inflammatory interleukins. The pro-inflammatory properties of IL-17 and its impact on the tumor microenvironment or autoimmune diseases are characterized, but new dimensions of IL-17 activity that promotes embryo implantation are not well explored. In the search for answers, our study compared concentrations of growth factors IGF1, GH, and interleukins IL-6 and IL-17 in the follicular fluid (FF) from 140 women divided into two groups depending on bad (G1) or good prognosis (G2) and investigated the relationships between these FF components’ levels and the main parameters of IVF. GH, IGF1, and IL-6 were significantly higher for G2. For GH, it was negatively correlated to patient age and positively correlated to maturity rate and IGF1. Moreover, GH and IGF1 were correlated to the top embryo rate and cumulative pregnancy rate. Regarding IL-6, it was correlated to IGF1 level, endometrium thickness, and implantation rate. As for IL-17, it was only correlated to IL-6. Consequently, all these FF components were predictive of oocyte quality except IL-17. GH seemed to be the best biomarker of this quality.

The Regulatory Roles of Chemerin-Chemokine-Like Receptor 1 Axis in Placental Development and Vascular Remodeling During Early Pregnancy

Chemerin is an adipokine that regulates metabolism in pregnancy. An elevation of serum chemerin level is associated with pregnancy complications. Consistently, we demonstrated that the chemerin expression was increased in placenta of preeclamptic patients at deliveries. The G protein-coupled receptor chemokine-like receptor 1 (CMKLR1) mediates the actions of chemerin. The functions of the chemerin-CMKLR1 axis in maintaining pregnancy are still unknown. In this study, we demonstrated that CMKLR1 was expressed in the decidual natural killer (dNK) cells and chorionic villi of human. Chemerin suppressed the proliferation of the dNK cells in vitro. Specific antagonist of CMKLR1, α-Neta abolished the suppressive effect of spent medium from chemerin-treated dNK cells culture on extravillous trophoblast invasion. Activation of the chemerin-CMKLR1 axis promoted fusion and differentiation of human cytotrophoblast to syncytiotrophoblast in vitro. We generated Cmklr1 knockout mice and showed that the Cmklr1 deficiency negatively affected pregnancy outcome in terms of number of implantation sites, litter size and fetal weight at birth. Histologically, the Cmklr1 deficiency impaired formation of the syncytiotrophoblast layer II, induced enlargement of the maternal lacunae in the labyrinth, increased the diameter of the spiral arteries and increased trophoblast invasion in the decidua. The Cmklr1 deficient placenta also displayed an increased number of dNK cells and serum IL-15 level. In summary, the chemerin-CMKLR1 axis regulated placental development and spiral artery remodeling in early pregnancy.

The possible involvement of circRNA DMNT1/p53/JAK/STAT in gestational diabetes mellitus and preeclampsia

Circular RNA (circRNA) plays an important role in biological processes of gestational diabetes mellitus (GDM) and preeclampsia (PE). However, the mechanisms for circRNA DMNT1 (circ-DMNT1) in GDM and PE remain unclarified. The expression levels of circ-DMNT1 and p53 in GDM and PE were quantified by quantitative real-time polymerase chain reaction (qRT-PCR) and western blot analysis. When the expression of circ-DMNT1 or p53 was abnormal, cell counting kit-8 (CCK-8) assay, bromodeoxyuridine (BrdU) staining, flow cytometry, cell scratch, and Transwell assays were used to assess cell viability, proliferation, cell cycle, apoptosis, migration, and invasion of trophoblast cells, respectively. Subsequently, the binding relationship between circ-DMNT1 and p53 was verified by RNA pull-down and RIP analysis, followed by the determination of JAK/STAT pathway-related protein expression levels using western blot analysis. Both circ-DMNT1 and p53 were highly expressed in GDM and PE. Upregulation of circ-DMNT1 or p53 inhibited trophoblast cell viability, proliferation, migration, and invasion, meanwhile promoting cell apoptosis but blocking cell cycle progression. However, downregulation of circ-DMNT1 or p53 induced trophoblast cell survival. In GDM and PE, circ-DMNT1 activated the JAK/STAT pathway by binding to p53, which resulted in increased expression levels of p-JAK and p-STAT. The results suggested that circ-DMNT1 was involved in the deterioration of GDM and PE, possibly through inducing p53 expression and activating the JAK/STAT signaling pathway.

Maternal hypothyroidism reduces the expression of the kisspeptin/Kiss1r system in the maternal-fetal interface of rats

Alterations of circulating and placental levels of kisspeptin have been associated with gestational diseases. However, there are still no studies on the placental and decidual expression of Kiss1 and its receptor Kiss1r in maternal hypothyroidism, which is the aim of this work. We demonstrate that the fetoplacental restriction caused by hypothyroidism in rats is associated with a reduction in the Kiss1r expression and reduced Kiss1 and Kiss1r mRNA levels in the decidua and/or placenta. This demonstrate that fetoplacental restriction in hypothyroid rats is linked with a suppression of the kisspeptin/Kiss1r system at the maternal-fetal interface.

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.

Changes in Circulating Kisspeptin Levels During Each Trimester in Women With Antenatal Complications

CONTEXT

Antenatal complications such as hypertensive disorders of pregnancy (HDP), fetal growth restriction (FGR), gestational diabetes (GDM), and preterm birth (PTB) are associated with placental dysfunction. Kisspeptin has emerged as a putative marker of placental function, but limited data exist describing circulating kisspeptin levels across all 3 trimesters in women with antenatal complications.

OBJECTIVE

We aimed to assess whether kisspeptin levels are altered in women with antenatal complications.

METHODS

Women with antenatal complications (n = 105) and those with uncomplicated pregnancies (n = 265) underwent serial ultrasound scans and blood sampling at the Early Pregnancy Assessment Unit at Hammersmith Hospital, UK, at least once during each trimester (March 2014 to March 2017). The women with antenatal complications (HDP [n = 32], FGR [n = 17], GDM [n = 35], PTB [n = 11], and multiple complications [n=10]) provided 373 blood samples and the controls provided 930 samples. Differences in circulating kisspeptin levels were assessed.

RESULTS

Third-trimester kisspeptin levels were higher than controls in HDP but lower in FGR. The odds of HDP adjusted for gestational age, maternal age, ethnicity, BMI, smoking, and parity were increased by 30% (95% CI, 16%-47%; P < 0.0001), and of FGR were reduced by 28% (95% CI, 4-46%; P = 0.025), for every 1 nmol/L increase in plasma kisspeptin. Multiple of gestation-specific median values of kisspeptin were higher in pregnancies affected by PTB (P = 0.014) and lower in those with GDM (P = 0.020), but not significantly on multivariable analysis.

CONCLUSION

We delineate changes in circulating kisspeptin levels at different trimesters and evaluate the potential of kisspeptin as a biomarker for antenatal complications.

Metabolic Adaptations to Pregnancy in Healthy and Gestational Diabetic Pregnancies: The Pancreas - Placenta Axis

Normal pregnancy is associated with increased insulin resistance as a metabolic adaptation to the nutritional demands of the placenta and fetus, and this is amplified in obese mothers. Insulin resistance is normally compensated for by an adaptive increase in pancreatic β-cell mass together with enhanced glucose-stimulated insulin release. Placentally-derived hormones and growth factors are central to the altered pancreatic morphology and function. A failure of β-cells to undergo adaptive change after the first trimester has been linked with gestational diabetes. In the pregnant mouse, an increase in β-cell replication contributes to a 2-3-fold increase in mass peaking in late gestation, depending on the proliferation of existing β-cells, the differentiation of resident progenitor β-cells, or islet cell transdifferentiation. Using mouse models and human studies placenta- and islet of Langerhans-derived molecules have been identified that are likely to contribute to the metabolic adaptations to pregnancy and whose physiology is altered in the obese, glucose-intolerant mother. Maternal obesity during pregnancy can create a pro-inflammatory environment that can disrupt the response of the β-cells to the endocrine signals of pregnancy and limit the adaptive changes in β-cell mass and function, resulting in an increased risk of gestational diabetes.

Kisspeptin/Kiss1r system and angiogenic and immunological mediators at the maternal-fetal interface of domestic cats

The Kisspeptin/Kiss1r system is a key regulator of reproduction by stimulating gonadotrophin-releasing hormone and luteinizing hormone release, and in vitro studies have shown that Kisspeptin can modulate angiogenesis and immune function, factors that are also essential for reproduction However, there are no studies on the expression of Kisspeptin/Kiss1r at the maternal-fetal interface in domestic cats and its relationship with angiogenic and immunological mediators. Thus, our objective was to evaluate the spatiotemporal expression profile of Kisspeptin/Kiss1r and angiogenic and immunological mediators in the uterus and placenta of domestic cats during pregnancy. Uterus and placenta samples were collected from cats in mid pregnancy (N = 6) and late pregnancy (N = 6), in addition to uterus from non-pregnant cats in diestrus (N = 7), to evaluate protein and gene expression of kisspeptin (Kiss1), kisspeptin receptor (Kiss1r), vascular endothelial growth factor (VEGF), tyrosine kinase receptor (Flk-1), placental growth factor (PLGF), interferon gamma (INFγ), migration inhibiting factor (MIF), tumor necrosis factor (TNFα), interleukins (IL6 and IL10) by immunohistochemistry and quantitative polymerase chain reaction. Pregnancy increased the uterine expression of Kiss1 and Kiss1r, especially at the late pregnancy, in addition to upregulating INFy, MIF, Vegf, Il10, and Tnf and downregulating Plgf. Higher placental expression of Kiss1r and Plgf mRNA occurred at the late pregnancy, while the expression of Kiss1, VEGF, Flk-1, INFy, TNFα, Il6, and IL10 was higher in the mid of pregnancy. A positive correlation between Kiss1 and Tnf was observed in the placenta, while Kiss1r had a negative correlation with Infγ, Il6, and Il10. The findings reveal that Kisspeptin/Kiss1r and angiogenic and immunological mediators at the maternal-fetal interface of pregnant cat have a gene correlation and are modulated by the gestational age. These data suggest possible functional links of Kisspeptin in placental angiogenesis and immunology.

Kisspeptin receptor agonist has therapeutic potential for female reproductive disorders

BACKGROUNDKisspeptin is a key regulator of hypothalamic gonadotropin-releasing hormone (GnRH) neurons and is essential for reproductive health. A specific kisspeptin receptor (KISS1R) agonist could significantly expand the potential clinical utility of therapeutics targeting the kisspeptin pathway. Herein, we investigate the effects of a KISS1R agonist, MVT-602, in healthy women and in women with reproductive disorders.METHODSWe conducted in vivo and in vitro studies to characterize the action of MVT-602 in comparison with native kisspeptin-54 (KP54). We determined the pharmacokinetic and pharmacodynamic properties of MVT-602 (doses 0.01 and 0.03 nmol/kg) versus KP54 (9.6 nmol/kg) in the follicular phase of healthy women (n = 9), and in women with polycystic ovary syndrome (PCOS; n = 6) or hypothalamic amenorrhea (HA; n = 6). Further, we investigated their effects on KISS1R-mediated inositol monophosphate (IP1) and Ca2+ signaling in cell lines and on action potential firing of GnRH neurons in brain slices.RESULTSIn healthy women, the amplitude of luteinizing hormone (LH) rise was similar to that after KP54, but peaked later (21.4 vs. 4.7 hours; P = 0.0002), with correspondingly increased AUC of LH exposure (169.0 vs. 38.5 IU∙h/L; P = 0.0058). LH increases following MVT-602 were similar in PCOS and healthy women, but advanced in HA (P = 0.004). In keeping with the clinical data, MVT-602 induced more potent signaling of KISS1R-mediated IP1 accumulation and a longer duration of GnRH neuron firing than KP54 (115 vs. 55 minutes; P = 0.0012).CONCLUSIONTaken together, these clinical and mechanistic data identify MVT-602 as having considerable therapeutic potential for the treatment of female reproductive disorders.TRIAL REGISTRATIONInternational Standard Randomised Controlled Trial Number (ISRCTN) Registry, ISRCTN21681316.FUNDINGNational Institute for Health Research and NIH.

Role of Kisspeptin in Regulation of Reproductive and Immune Reactions

The work is focused on physiological role of the hormone kisspeptin produced by neurons of the hypothalamus anterior zone, which is a key regulator of reproduction processes. Role of the hormone in transmission of information on metabolic activity and induction of the secretion of gonadotropin-releasing hormone (GnRH) by the hypothalamus that determines gestation processes involving fertilization, placentation, fetal development, and child birth is considered. The literature data on molecular mechanisms and effects of kisspeptin on reproductive system including puberty initiation are summarized and analyzed. In addition, attention is paid to hormone-mediated changes in the cardiovascular system in pregnant women. For the first time, the review examines the effect of kisspeptin on functional activity of immune system cells presenting molecular mechanisms of the hormone signal transduction on the level of lymphoid cells that lead to the immune tolerance induction. In conclusion, a conceptual model is presented that determines the role of kisspeptin as an integrator of reproductive and immune functions during pregnancy.

Kisspeptins and Glucose Homeostasis in Pregnancy: Implications for Gestational Diabetes Mellitus-a Review Article

Gestational diabetes mellitus (GDM) is becoming an increasingly common complication of pregnancy with the global rise of obesity. The precise pathophysiological mechanisms underpinning GDM are yet to be fully elucidated. Kisspeptin, a peptide encoded by the KISS1 gene, is mainly expressed by placental syncytiotrophoblasts during pregnancy. It is an essential ligand for kisspeptin 1 receptor (KISS1R), which is expressed by both the villous and invasive extravillous cytotrophoblast cells. Circulatory kisspeptins rise dramatically in the second and third trimester of pregnancy coinciding with the period of peak insulin resistance. Kisspeptins stimulate glucose-dependent insulin secretion and decreased plasma levels inversely correlate with markers of insulin resistance. Additionally, kisspeptins play a critical role in the regulation of appetite, energy utilisation and glucose homeostasis. GDM pregnancies have been associated with low circulatory kisspeptins, despite higher placental kisspeptin and KISS1R expression. This review evaluates the role of kisspeptin in insulin secretion, resistance and regulation of appetite as well as its implications in GDM.

Peripheral action of kisspeptin at reproductive tissues-role in ovarian function and embryo implantation and relevance to assisted reproductive technology in livestock: a review

Kisspeptin (KISS1) is encoded by the KISS1 gene and was initially found to be a repressor of metastasis. Natural mutations in the KISS1 receptor gene (KISS1R) were subsequently shown to be associated with idiopathic hypothalamic hypogonadism and impaired puberty. This led to interest in the role of KISS1 in reproduction. It was established that KISS1 had a fundamental role in the control of gonadotropin releasing hormone (GnRH) secretion. KISS1 neurons have receptors for leptin and estrogen receptor α (ERα), which places KISS1 at the gateway of metabolic (leptin) and gonadal (ERα) regulation of GnRH secretion. More recently, KISS1 has been shown to act at peripheral reproductive tissues. KISS1 and KISS1R genes are expressed in follicles (granulosa, theca, oocyte), trophoblast, and uterus. KISS1 and KISS1R proteins are found in the same tissues. KISS1 appears to have autocrine and paracrine actions in follicle and oocyte maturation, trophoblast development, and implantation and placentation. In some studies, KISS1 was beneficial to in vitro oocyte maturation and blastocyst development. The next phase of KISS1 research will explore potential benefits on embryo survival and pregnancy. This will likely involve longer-term KISS1 treatments during proestrus, early embryo development, trophoblast attachment, and implantation and pregnancy. A deeper understanding of the direct action of KISS1 at reproductive tissues could help to achieve the next step change in embryo survival and improvement in the efficiency of assisted reproductive technology.

miR‑181b‑5p inhibits trophoblast cell migration and invasion through targeting S1PR1 in multiple abnormal trophoblast invasion‑related events

Normal placentation and successful maintenance of pregnancy depend on the successful migration and invasion of trophoblasts into maternal tissues. Previous studies reported that microRNAs (miRs) are expressed in trophoblasts, and can regulate their migration and invasion. The present study aimed to investigate miR‑181b‑5p function in HTR‑8/SVneo trophoblasts and explore its underlying mechanism in the pathogenesis of multiple abnormal trophoblast invasion‑related events. Reverse‑transcription quantitative PCR and western blotting were used to test the expression of miR‑181b‑5p and sphingosine‑1‑phosphate receptor 1 (S1PR1) in samples of multiple abnormal trophoblast invasion‑related events. Transwell invasion and wound healing assays were performed to determine cell invasion and migration abilities. A luciferase reporter assay was conducted to identify the downstream target of miR‑181b‑5p. Overexpression of miR‑181b‑5p suppressed HTR‑8/SVneo cell migration and invasion, whereas inhibition of miR‑181b‑5p induced an opposite effect. The S1PR1 gene was further identified as a novel direct target of miR‑181b‑5p. Specifically, miR‑181b‑5p bound directly to the 3'‑untranslated region of S1PR1 and suppressed its expression. Moreover, overexpression of S1PR1 reversed the inhibitory effect of miR‑181b‑5p. Taken together, ectopic expression of miR‑181b‑5p impaired the migration and invasion of trophoblasts by directly targeting S1PR1, thereby providing new insights into the pathogenesis of multiple abnormal trophoblast invasion‑related events.

Is placental KISS-1 expression associated with first trimester abortion spontaneous?

Objective

Several studies have examined biological markers during the first trimester to predict the maintenance of a healthy pregnancy. One such marker is kisspeptin, which is encoded by the KISS-1 gene. We aimed to determine whether first-trimester pregnancy losses were associated with levels of placental KISS-1 expression.

Methods

This prospective case control study was conducted at a tertiary center. The study group included 27 and 24 patients who underwent dilation and curettage at <10 weeks of gestation, due to first trimester spontaneous pregnancy loss and for elective termination (control), respectively. Placental and decidual tissues from all patients were sectioned and immunohistochemically analyzed for kisspeptin.

Results

Age, gravida status, parity number, gestational week, and number of previous abortions did not significantly differ between the groups. KISS-1 expression levels were significantly lower in the group with spontaneous abortion compared with the group with elective termination. The median staining intensity of KISS-1 expression in the elective and spontaneous termination groups were 3 (strong) and 2 (moderate), respectively (P=0.004). KISS-1 expression levels were significantly lower among patients with previous abortions in the elective termination group (P=0.002).

Conclusion

KISS-1 expression levels were found to be significantly reduced in patients with spontaneous pregnancy loss; KISS-1 plays an important role in the implantation and continuation of pregnancy.

Placental protein expression of kisspeptin-1 (KISS1) and the kisspeptin-1 receptor (KISS1R) in pregnancy complicated by diabetes mellitus or preeclampsia

PURPOSE

Kisspeptins regulate the trophoblast invasion. The disturbance of this process might lead to the development of preeclampsia (PE). Diabetes mellitus (DM) is associated with the high rate of this complication. The main hypothesis was to investigate the placental protein expression of kisspeptin-1 (KISS1) and its receptor (KISS1R) in diabetic, preeclamptic, and healthy pregnancies.

METHODS

Placentae (n = 65) were divided into the following groups: the control group (n = 20), either PE or non-PE type-1 diabetes mellitus (T1DM) (n = 10), either PE or non-PE type-2 diabetes mellitus (T2DM) (n = 10), either PE or non-PE gestational diabetes mellitus (GDM) (n = 10) and preeclampsia without diabetes (PE) (n = 15). Immunohistochemistry analysis was used for demonstrating the presence and location of KISS1/KISS1R in placental tissue and to measure the area of immunopositive expression. Correlation analyses were performed to detect the links between protein expression of these biomarkers and the main obstetric outcomes.

RESULTS

The highest placental protein expressions of KISS1 were detected in the PE (35.4%) and GDM (33.2%) groups. In case of DM, levels of KISS1 expression depended on the presence of PE and were higher compared with DM no PE and control groups: (30.6%) in T1DM + PE and (30.1%) in T2DM + PE group. The lowest expression was detected in the control group (14.1%). The expression of KISS1R was higher in DM and PE compared to the control group. We detected the strong direct link between PE and placental expression of KISS1 (r = 0.81) and KISS1R (r = 0.56), and inverse correlation link between KISS1 and preterm birth weight (r = - 0.73). The low correlation links were found between KISS1 and IUGR (r = 0.29), and preterm birth (r = 0.24). The same trend was detected for KISS1R. We did not find any significant correlations between placental expressions of KISS/KISS1R and placental weight or HbA1c levels.

CONCLUSION

Increased expression levels of KISS1 and KISS1R in case of diabetes mellitus may play a role in the altered placentation process and lead to the development of preeclampsia.

Serum Levels of Kisspeptin Are Elevated in Patients with Pancreatic Cancer

Pancreatic adenocarcinoma (PDAC) still represents a devastating disease associated with a very limited survival. Novel biomarkers allowing an early diagnosis as well as an optimal selection of suitable treatment options for individual patients are urgently needed to improve the dismal outcome of PDAC patients. Recently, alterations of Kisspeptin serum levels, a member of the adipokine family, were described in various types of cancers. However, the role of circulating Kisspeptin as a biomarker in PDAC patients is poorly defined. In this study, we measured Kisspeptin serum levels in a cohort of 128 prospectively enrolled PDAC patients undergoing surgical resection as well as 36 healthy controls. Kisspeptin concentrations were elevated in PDAC patients compared to control samples. Nevertheless, Kisspeptin serum levels were independent of tumor-related factors such as the tumor grading, TNM stage, or clinical features such as the ECOG performance status. Finally, in our analysis, neither preoperative nor postoperative Kisspeptin levels turned out as a significant predictor of overall survival after tumor resection. In conclusion, our data suggest that Kisspeptin concentrations are altered in PDAC patients but do not allow to predict patients' outcome after resection of PDAC.

The role of kisspeptin system in cancer biology

Kisspeptins are a family of neuropeptides that are known to be critical in puberty initiation and ovulation. Apart from that kisspeptin derived peptides (KPs) are also known for their antimetastatic activities in several malignancies. Herein we report recent evidence of the role of kisspeptins in cancer biology and we examine the prospective of targeting the kisspeptin pathways leading to a better prognosis in patients with malignant diseases.

Reproductive functions of Kisspeptin/KISS1R Systems in the Periphery

Kisspeptin and its G protein-coupled receptor KISS1R play key roles in mammalian reproduction due to their involvement in the onset of puberty and control of the hypothalamic-pituitary-gonadal axis. However, recent studies have indicated a potential role of extra-hypothalamic kisspeptin in reproductive function. Here, we summarize recent advances in our understanding of the physiological significance of kisspeptin/KISS1R in the peripheral reproductive system (including the ovary, testis, uterus, and placenta) and the potential role of kisspeptin/KISS1R in reproductive diseases. A comprehensive understanding of the expression, function, and potential molecular mechanisms of kisspeptin/KISS1R in the peripheral reproductive system will contribute to the diagnosis, treatment and prevention of reproductive diseases.

Predictive value of serum kisspeptin concentration at 14 and 21 days after frozen-thawed embryo transfer

RESEARCH QUESTION

Can serum kisspeptin levels 14 and 21 days after frozen-thawed embryo transfer predict the early pregnancy outcome of patients?

DESIGN

Prospective study, with 133 patients undergoing frozen-thawed embryo transfer. Patients were divided into non-pregnant group and pregnant group (including biochemical pregnancy, singleton pregnancy, miscarriage and twin groups).

RESULTS

Serum kisspeptin levels on day 21 were significantly higher than day 14 in singleton pregnancy, miscarriage and twin groups (all P < 0.0001), but not in the biochemical pregnancy group. Similarly, serum human chorionic gonadotrophin (HCG) levels were higher on day 21 compared with day 14 except for the biochemical pregnancy group. Compared with the twin group (296.9 pg/ml), the other four groups showed significantly higher serum kisspeptin levels on day 14 (non-pregnant 548.9, biochemical pregnancy 440.4, miscarriage 434.9, singleton pregnancy group 420.9 pg/ml, P < 0.01, P = 0.016, P = 0.034, P = 0.036, respectively). The miscarriage (762.2 pg/ml), singleton pregnancy (730.8 pg/ml) and twin groups (826.3 pg/ml) had significantly higher kisspeptin levels than the biochemical pregnancy group (397.3 pg/ml) on day 21 (P < 0.001, P < 0.01, P < 0.001, respectively). Serum kisspeptin levels on day 14 were negatively correlated with embryo implantation rate (P = 0.035, R² = -0.880). Serum kisspeptin levels on day 21 have a poor predictive value of miscarriage compared with serum HCG levels (area under the curve = 0.53 and 0.78, respectively).

CONCLUSIONS

Serum kisspeptin levels on day 14 are negatively correlated with embryo implantation rate. Serum kisspeptin levels on day 21 have a poor predictive value of miscarriage.

Prognostic value of repeated serum kisspeptin measurements in early first trimester pregnancy: a preliminary study

RESEARCH QUESTION

What is the diagnostic value of maternal kisspeptin in patients with asymptomatic first-trimester pregnancies, and what is the prognostic significance of kisspeptin versus beta-HCG in early pregnancies.

DESIGN

Case-control study in academic medical centres. Patients with no confounding co-morbidities who conceived by IVF and intracytoplasmic sperm injection were analysed. Maternal serum samples were assessed at the time of pregnancy testing. Women who achieved a positive pregnancy test were asked to take serum samples 4 days later. According to the follow-up results, patients who experienced biochemical pregnancy loss (n = 24) and early miscarriage (n = 21), and women who achieved a viable pregnancy (n = 28), were included in this study. Serum samples were collected to detect kisspeptin and beta-HCG, respectively.

RESULTS

Single serum determinations of kisspeptin and beta-HCG were correlated with the different pregnancy outcomes. Women who experienced biochemical pregnancy loss showed lower kisspeptin levels than those in groups B and C. No significant difference, however, was observed at the time of pregnancy testing in women who had experienced early miscarriage and those who had achieved viable pregnancy. Sequential measurements of serum kisspeptin are not as effective as beta-HCG in determining pregnancy outcome. Increased kisspeptin level was associated with reduced miscarriage risk.

CONCLUSION

Single serum measurement of kisspeptin is significantly altered in pregnant and non-pregnant women. However, it failed to discriminate between miscarriage and ongoing pregnancies in first-trimester pregnancy. Neither single nor sequential kisspeptin have higher diagnostic performance for miscarriage than beta-HCG in early stage.

Role of Endoplasmic Reticulum Stress in Proinflammatory Cytokine-Mediated Inhibition of Trophoblast Invasion in Placenta-Related Complications of Pregnancy

Shallow extravillous trophoblast (EVT) invasion is central to the pathophysiology of many pregnancy complications. Invasion is mediated partially by matrix metalloproteinases (MMPs). MMP-2 is highly expressed in early pregnancy. MMP activity can be regulated by proinflammatory cytokines, which also induce endoplasmic reticulum (ER) stress in other cells. We investigated whether proinflammatory cytokines regulate MMP-2 activity through ER stress response pathways in trophoblast before exploring potential regulatory mechanisms. There was increased immunoreactivity of heat shock 70-kDa protein 5, also known as 78-kDa glucose regulated protein, in cells of the placental bed, including EVTs, in cases of early-onset preeclampsia compared with normotensive controls. Treating EVT-like JEG-3 and HTR8/SVneo cells with ER stress inducers (tunicamycin and thapsigargin) suppressed MMP2 mRNA and protein expression, secretion, and activity and reduced their invasiveness. A cocktail of proinflammatory cytokines (IL-1β, tumor necrosis factor-α, and interferon-γ) suppressed MMP-2 activity in JEG-3 cells and was accompanied by activation of the PKR-like ER kinase (PERK)-eukaryotic translation initiation factor 2A (EIF2A) arm of the ER stress pathway. Knockdown of ATF4, a downstream transcriptional factor of the PERK-EIF2A pathway, by small interference RNA, restored MMP2 expression but not cellular proteins. However, suppression of EIF2A phosphorylation with a PERK inhibitor, GSK2606414, under ER stress, restored MMP-2 protein. ER stress regulates MMP-2 expression at both the transcriptional and translational levels. This study provides the first mechanistic linkage by which proinflammatory cytokines may modulate trophoblast invasion through ER stress pathways.

Plasma kisspeptin levels are associated with insulin secretion in nondiabetic individuals

To evaluate if plasma kisspeptin concentrations are associated with insulin secretion, as suggested by recent in vitro studies, independently of confounders. 261 nondiabetic subjects were stratified into tertiles according to kisspeptin values. Insulin secretion was assessed using indexes derived from oral glucose tolerance test (OGTT). After adjusting for age, gender, and BMI, subjects in the highest (tertile 3) kisspeptin group exhibited significantly lower values of insulinogenic index, corrected insulin response (CIR₃₀), and Stumvoll indexes for first-phase and second-phase insulin release as compared with low (tertile 1) or intermediate (tertile 2) kisspeptin groups. Univariate correlations between kisspeptin concentration and metabolic variables showed that kisspeptin concentration was significantly and positively correlated with age, blood pressure, and 2-h post-load glucose, and inversely correlated with BMI, and waist circumference. There was an inverse relationship between kisspeptin levels and OGTT-derived indexes of glucose-stimulated insulin secretion. A multivariable regression analysis in a model including all the variables significantly correlated with kisspeptin concentration showed thar age (β = -0.338, P<0.0001), BMI (β = 0.272, P<0.0001), 2-h post-load glucose (β = -0.229, P<0.0001), and kisspeptin (β = -0.105, P = 0.03) remained associated with insulinogenic index. These factors explained 34.6% of the variance of the insulinogenic index. In conclusion, kisspeptin concentrations are associated with insulin secretion independently of important determinants of glucose homeostasis such as gender, age, adiposity, 2-h post-load glucose, and insulin sensitivity.

Transcriptional Dynamics of Cultured Human Villous Cytotrophoblasts

During human pregnancy, cytotrophoblasts (CTBs) play key roles in uterine invasion, vascular remodeling, and anchoring of the feto-placental unit. Due to the challenges associated with studying human placentation in utero, cultured primary villous CTBs are used as a model of the differentiation pathway that leads to invasion of the uterine wall. In vitro, CTBs emulate in vivo cell behaviors, such as migration, aggregation, and substrate penetration. Although some of the molecular features related to these cell behaviors have been described, the underlying mechanisms, at a global level, remain undefined at midgestation. Thus, in this study, we characterized second-trimester CTB differentiation/invasion in vitro, correlating the major morphological transitions with the transcriptional changes that occurred at these steps. After plating on Matrigel as individual cells, CTBs migrated toward each other and formed multicellular aggregates. In parallel, using a microarray approach, we observed differentially expressed (DE) genes across time, which were enriched for numerous functions, including cell migration, vascular remodeling, morphogenesis, cell communication, and inflammatory signaling. DE genes encoded several molecules that we and others previously linked to critical CTB function in vivo, suggesting that the novel DE molecules we discovered played important roles. Immunolocalization confirmed that CTBs in situ gave a signal for two of the most highly expressed genes in vitro. In summary, we characterized, at a global level, the temporal dynamics of primary human CTB gene expression in culture. These data will enable future analyses of various types of in vitro perturbations-for example, modeling disease processes and environmental exposures.

Cancer metastasis: enactment of the script for human reproductive drama

Based on compelling evidence from many biological disciplines, we put forth a hypothesis for cancer metastasis. In the hypothesis, the metastatic cascade is depicted as human reproduction in miniature. Illustrated in a reproductive light, the staggering resemblance of cancer metastasis to human reproduction becomes evident despite some ostensible dis-similarities. In parallel to the appearance of primordial germ cells during early embryogenesis, the cancer reproductive saga starts with the separation of metastasis initiating cells (MICs) from cancer initiating cells when the primary cancer is still in its infancy. Prime MICs embark on a journey to the host bone marrow where they undergo further development and regulation. Migrating MICs are guided by the same CXCR4/CYCL12 axis as used in the migration of primordial germ cells to the genital ridge. Like the ovary, the host bone marrow features immune privileges, coolness, hypoxia and acidity which are essential for stemness maintenance and regulation. Opportune activation of the MICs via fusion with bone marrow stem cells triggers a frenzy of cellular proliferation and sets them on the move again. This scenario is akin to oocyte fertilization in the Fallopian tube and its subsequent journey towards the decidum. Just as the human reproductive process is plagued with undesirable outcomes so is the cancer metastasis highly inefficient. The climax of the cancer metastatic drama (colonization) is reached when proliferating MIC clusters attempt to settle down on decidum-like premetastatic sites. Successfully colonized clusters blossom into overt macrometastases only after the execution of sophisticated immunomodulation, angiogenesis and vascular remodeling. Similarly, the implanted blastomere needs to orchestrate these feats before flourishing into a new life. What is more, the cancer reproductive drama seems to be directed by a primordial hypothalamus–pituitary–gonad axis. Pursuing this reproductive trail could lead to new frontiers and breakthroughs in cancer research and therapeutics.

Transthyretin regulates the migration and invasion of JEG-3 cells

Preeclampsia (PE) is a pregnancy-specific disorder characterized by new-onset hypertension and proteinuria that occurs after 20 weeks of gestation. It involves several organs and continues to be a leading cause of maternal and perinatal morbidity and mortality worldwide. Shallow trophoblast invasion is a common pathological feature of PE. Transthyretin (TTR) is a 56-kDa homotetrameric protein that binds thyroid hormone and retinol binding protein. Dysregulated TTR expression has been found in cases of PE. The aim of the present study was to determine the functional role of TTR in the migration and invasion of JEG-3 choriocarcinoma cells. JEG-3 cells were transfected with a plasmid construct expressing TTR (pCMV-Myc-TTR) or an empty plasmid (pCMV-Myc). Cell migration and invasion capacities were assessed by Transwell migration and invasion assays, respectively. These experiments demonstrated that TTR overexpression significantly increased the migration and invasion potential of JEG-3 cells. Matrix metalloproteinases (MMPs) are a family of zinc-containing endopeptidases capable of degrading a wide range of extracellular matrix components. Western blot analysis revealed that TTR overexpression resulted in significantly increased levels of MMP2 and MMP9 in JEG-3 cells. In conclusion, our findings suggest an important role for TTR in regulating trophoblast invasion and migration, representing a possible underlying pathological and molecular mechanisms of PE.

Kisspeptin-10 and the G protein-coupled receptor 54 are differentially expressed in the canine pregnant uterus and trophoblast cells

Uterine tissue was collected from bitches after ovariohysterectomy at different times after ovulation. Samples were assigned to four groups: metestrous non-pregnant, day 10-12, n = 4; pre-implantation, day 10-12, n = 9; post-implantation, day 18-25, n = 13; mid-gestation, day 30-40, n = 7. RT-qPCR detection was performed for kiss1 and the G protein-coupled receptor 54 (GPR54, specific receptor for kisspeptin). In addition, immunohistochemistry was performed for detection of kisspeptin-10 (KP-10), GPR54, as well as pan-cytokeratin and vimentin. The latter two were included to differentiate the different placental cell types. The percentage of positive stained cells was evaluated, and an immunoreactivity score (IRS) was obtained by multiplying the labelling intensity score (0-3) with the percentage of immunolabelled cells (range: 0-300). In non-pregnant and pre-implantation tissues, gene expression was highly variable for kiss1 and GPR54. Expression of GPR54 was higher before embryo adhesion than during post-implantation and mid-gestation (p < .05), whereas there was no difference found between groups for kiss1. Except during the pre-implantation period, KP-10 expression was higher in the non-pregnant uterus compared to all gestational periods investigated, indicating a pregnancy-related downregulation. In the pre-implantation period, KP-10 was present in larger vessels only, whereas the presence of GPR54 in vessels was found in all samples, with most labelling in the post-implantation period. KP-10 was present in superficial uterine glands, GPR54 in superficial and deep uterine glands of the post-implantation uterus. In myocytes, the highest staining for KP-10 was seen in the non-pregnant uterus, whereas the highest staining for GPR54 was seen in post-implantation and mid-gestation. Syncytiotrophoblast cells stained for both KP-10 and GPR54 in post-implantation and mid-gestation, with maximum intensity for GPR54 in the latter. We conclude that KP-10 and GPR54 are expressed in the canine uterus and trophoblast cells. However, during pregnancy, expression of both proteins seems to be differentially regulated.

Cancer susceptibility and reproductive trade-offs: a model of the evolution of cancer defences

The factors influencing cancer susceptibility and why it varies across species are major open questions in the field of cancer biology. One underexplored source of variation in cancer susceptibility may arise from trade-offs between reproductive competitiveness (e.g. sexually selected traits, earlier reproduction and higher fertility) and cancer defence. We build a model that contrasts the probabilistic onset of cancer with other, extrinsic causes of mortality and use it to predict that intense reproductive competition will lower cancer defences and increase cancer incidence. We explore the trade-off between cancer defences and intraspecific competition across different extrinsic mortality conditions and different levels of trade-off intensity, and find the largest effect of competition on cancer in species where low extrinsic mortality combines with strong trade-offs. In such species, selection to delay cancer and selection to outcompete conspecifics are both strong, and the latter conflicts with the former. We discuss evidence for the assumed trade-off between reproductive competitiveness and cancer susceptibility. Sexually selected traits such as ornaments or large body size require high levels of cell proliferation and appear to be associated with greater cancer susceptibility. Similar associations exist for female traits such as continuous egg-laying in domestic hens and earlier reproductive maturity. Trade-offs between reproduction and cancer defences may be instantiated by a variety of mechanisms, including higher levels of growth factors and hormones, less efficient cell-cycle control and less DNA repair, or simply a larger number of cell divisions (relevant when reproductive success requires large body size or rapid reproductive cycles). These mechanisms can affect intra- and interspecific variation in cancer susceptibility arising from rapid cell proliferation during reproductive maturation, intrasexual competition and reproduction.

Placental Kisspeptins Differentially Modulate Vital Parameters of Estrogen Receptor-Positive and -Negative Breast Cancer Cells

Kisspeptins (KPs) are major regulators of trophoblast and cancer invasion. Thus far, limited and conflicting data are available on KP-mediated modulation of breast cancer (BC) metastasis; mostly based on synthetic KP-10, the most active fragment of KP. Here, we report for the first time comprehensive functional effects of term placental KPs on proliferation, adhesion, Matrigel invasion, motility, MMP activity and pro-inflammatory cytokine production in MDA-MB-231 (estrogen receptor-negative) and MCF-7 (estrogen receptor-positive). KPs were expressed at high level by term placental syncytiotrophoblasts and released in soluble form. Placental explant conditioned medium containing KPs (CM) significantly reduced proliferation of both cell types compared to CM without (w/o) KP (CM-w/o KP) in a dose- and time-dependent manner. In MDA-MB-231 cells, placental KPs significantly reduced adhesive properties, while increased MMP9 and MMP2 activity and stimulated invasion. Increased invasiveness of MDA-MB-231 cells after CM treatment was inhibited by KP receptor antagonist, P-234. CM significantly reduced motility of MCF-7 cells at all time points (2–30 hr), while it stimulated motility of MDA-MB-231 cells. These effects were reversed by P-234. Co-treatment with selective ER modulators, Tamoxifen and Raloxifene, inhibited the effect of CM on motility of MCF-7 cells. The level of IL-6 in supernatant of MCF-7 cells treated with CM was higher compared to those treated with CM-w/o KP. Both cell types produced more IL-8 after treatment with CM compared to those treated with CM-w/o KP. Taken together, our observations suggest that placental KPs differentially modulate vital parameters of estrogen receptor-positive and -negative BC cells possibly through modulation of pro-inflammatory cytokine production.

Expression and Regulation of Pituitary Adenylate Cyclase-Activating Polypeptide in Rat Placental Cells

Pituitary adenylate cyclase-activating polypeptide (PACAP) was first identified as a hypophysiotropic factor that regulates pituitary cell functions and has been subsequently shown to be widely distributed and have multiple functions. The PACAP is known to be expressed in placental tissues and is suggested to have a critical role in physiological function of the placenta. In addition to PACAP, the hypothalamic peptides kisspeptin and gonadotropin-releasing hormone (GnRH) are also expressed in placental cells. In this study, we used primary cultures of placental tissues from rats of 16 to 18 days gestation and examined the regulation and function of PACAP. The PACAP messenger RNA (mRNA) expression and PACAP-immunoreactive cells were detected in primary cultures of rat placental cells. The PACAP mRNA expression in placental cells was upregulated in the presence of the sex steroids estradiol and progesterone; however, their combined treatment failed to enhance their individual effects. When the cells were stimulated with kisspeptin, PACAP mRNA expression was increased. Similarly, GnRH had a stimulatory effect on PACAP expression. Conversely, kisspeptin expression in placental cells was increased by PACAP stimulation, whereas PACAP failed to stimulate GnRH mRNA expression in these cells. Finally, we found that PACAP had a stimulatory effect on human chorionic gonadotropin expression in placental cells. Our current observations suggest that the hypothalamic peptides PACAP, kisspeptin, and GnRH are interrelated and maintain placental functions.

Intrauterine trophoblast migration: A comparative view of humans and rodents

Trophoblast migration and invasion through the decidua and maternal uterine spiral arteries are crucial events in placentation. During this process, invasive trophoblast replace vascular endothelial cells as the uterine arteries are remodeled to form more permissive vessels that facilitate adequate blood flow to the growing fetus. Placentation failures resulting from either extensive or shallow trophoblastic invasion can cause pregnancy complications such as preeclampsia, intrauterine growth restriction, placenta creta, gestational trophoblastic disease and even maternal or fetal death. Consequently, the use of experimental animal models such as rats and mice has led to great progress in recent years with regards to the identification of mechanisms and factors that control trophoblast migration kinetics. This review aims to perform a comparative analysis of placentation and the mechanisms and factors that coordinate intrauterine trophoblast migration in humans, rats and mice under physiological and pathological conditions.

IgG expression in trophoblasts derived from placenta and gestational trophoblastic disease and its role in regulating invasion

Immunoglobulin G (IgG) is an important humoral immune factor, which plays a role in innate immunity of the fetus. IgG immunoreactivity was often seen in trophoblasts of placenta. Traditionally, IgG in trophoblasts was believed to be transported from the maternal blood through neonatal Fc receptor (FcRn). Here, we explored the phenomenon of IgG expression and its role in regulating invasion in trophoblasts derived from normal placenta and gestational trophoblastic disease (GTD). IgG expression was detected with an emphasis on mRNA transcripts by using reverse transcription-polymerase chain reaction and hybridization in situ, besides evaluated at the protein level with immunohistochemistry and immunofluorescence. The migration and attachment of normal trophoblast cell line (TEV-1) and choriocarcinoma cell line (JAR) were inhibited with down-regulation of IgG expression. Methotrexate promoted the differentiation of JAR cell line; however, it had little effect on the differentiation of TEV-1 cell line. IgG expression, migration, and attachment of JAR and TEV-1 cell lines were decreased in the presence of methotrexate. Furthermore, statistical analysis showed that the differences in migration and attachment were significant (P < 0.05) for JAR cell line, while no significant difference was found for TEV-1 cell line. Collectively, these results confirmed that with the progression from normal placenta to GTD, the expression of IgG was increased in trophoblasts, which might actively promote the migration and attachment of trophoblasts as an important regulating factor.

The identification of elevated urinary kisspeptin-immunoreactivity during pregnancy

BACKGROUND

Kisspeptin is an arginine-phenylalanine amide peptide hormone critical for reproductive function. Kisspeptin is also abundantly expressed in the placenta, where it has an important physiological role in regulating placental invasion. Accordingly, plasma kisspeptin concentrations rise dramatically during normal pregnancy. However, lower plasma concentrations of kisspeptin are associated with obstetric complications such as pre-eclampsia. It is not currently known whether kisspeptin-immunoreactivity (IR) can be detected in bodily fluids not requiring invasive collection such as saliva or urine.

AIM

To determine the clinical utility of urinary and salivary kisspeptin measurement in healthy pregnant women.

METHODS

Forty-nine healthy third trimester pregnant women (gestational age 34 ± 0.6 w) from a single maternity unit and 50 healthy non-pregnant women were recruited. Urine, saliva and blood were simultaneously collected from all volunteers. Kisspeptin concentrations were determined by in-house manual radioimmunoassay.

RESULTS

Mean concentrations of plasma kisspeptin-IR were over 200-fold greater in third trimester pregnant women compared with non-pregnant women (13,783 ± 864 pmol/L, pregnant; 65 ± 13 pmol/L, non-pregnant; p < 0.0001). The urine kisspeptin:creatinine ratio was greater in pregnant women when compared with non-pregnant women (urine kisspeptin:creatinine: 37 ± 6 pmol/µmol, pregnant; 7 ± 1 pmol/µmol, non-pregnant; p < 0.0001). Mean concentrations of salivary kisspeptin-IR were not statistically different between pregnant and non-pregnant women (123 ± 34 pmol/L, pregnant; 83 ± 33 pmol/L, non-pregnant; p = 0.2).

CONCLUSION

We demonstrate for the first time that kisspeptin-IR is elevated in urine during pregnancy. Urinary measurement of kisspeptin-IR may, therefore, offer a non-invasive and simple method of screening for pregnancy and obstetric complications.

Kisspeptin regulation of genes involved in cell invasion and angiogenesis in first trimester human trophoblast cells

The precise regulation of extravillous trophoblast invasion of the uterine wall is a key process in successful pregnancies. Kisspeptin (KP) has been shown to inhibit cancer cell metastasis and placental trophoblast cell migration. In this study primary cultures of first trimester human trophoblast cells have been utilized in order to study the regulation of invasion and angiogenesis-related genes by KP. Trophoblast cells were isolated from first trimester placenta and their identity was confirmed by immunostaining for cytokeratin-7. Real-time quantitative RT-PCR demonstrated that primary trophoblast cells express higher levels of GPR54 (KP receptor) and KP mRNA than the trophoblast cell line HTR8Svneo. Furthermore, trophoblast cells also expressed higher GPR54 and KP protein levels. Treating primary trophoblast cells with KP induced ERK1/2 phosphorylation, while co-treating the cells with a KP antagonist almost completely blocked the activation of ERK1/2 and demonstrated that KP through its cognate GPR54 receptor can activate ERK1/2 in trophoblast cells. KP reduced the migratory capability of trophoblast cells in a scratch-migration assay. Real-time quantitative RT-PCR demonstrated that KP treatment reduced the expression of matrix metalloproteinase 1, 2, 3, 7, 9, 10, 14 and VEGF-A, and increased the expression of tissue inhibitors of metalloproteinases 1 and 3. These results suggest that KP can inhibit first trimester trophoblast cells invasion via inhibition of cell migration and down regulation of the metalloproteinase system and VEGF-A.

Expression and function of kisspeptin during mouse decidualization

BACKGROUND

Plasma kisspeptin levels dramatically increased during the first trimester of human pregnancy, which is similar to pregnancy specific glycoprotein-human chorionic gonadotropin. However, its particular role in the implantation and decidualization has not been fully unraveled. Here, the study was conducted to investigate the expression and function of kisspeptin in mouse uterus during early pregnancy and decidualization.

METHODOLOGY/PRINCIPAL FINDINGS

Quantitative PCR results demonstrated that Kiss1 and GPR54 mRNA levels showed dynamic increase in the mouse uterus during early pregnancy and artificially induced decidualization in vivo. KISS-1 and GPR54 proteins were spatiotemporally expressed in decidualizing stromal cells in intact pregnant females, as well as in pseudopregnant mice undergoing artificially induced decidualization. In the ovariectomized mouse uterus, the expression of Kiss1 mRNA was upregulated after progesterone or/and estradiol treatment. Moreover, in a stromal cell culture model, the expression of Kiss1 and GPR54 mRNA gradually rise with the progression of stromal cell decidualization, whereas the attenuated expression of Kiss1 using small interfering RNA approaches significantly blocked the progression of stromal cell decidualization.

CONCLUSION

our results demonstrated that Kiss1/GPR54 system was involved in promoting uterine decidualization during early pregnancy in mice.

Dependence of fertility on kisspeptin-Gpr54 signaling at the GnRH neuron

Signaling between kisspeptin and its receptor, G-protein-coupled receptor 54 (Gpr54), is now recognized as being essential for normal fertility. However, the key cellular location of kisspeptin-Gpr54 signaling is unknown. Here we create a mouse with a GnRH neuron-specific deletion of Gpr54 to assess the role of gonadotropin-releasing hormone (GnRH) neurons. Mutant mice are infertile, fail to go through puberty and exhibit markedly reduced gonadal size and follicle-stimulating hormone levels alongside GnRH neurons that are unresponsive to kisspeptin. In an attempt to rescue the infertile phenotype of global Gpr54⁻/⁻ mutants, we use BAC transgenesis to target Gpr54 to the GnRH neurons. This results in mice with normal puberty onset, estrous cyclicity, fecundity and a recovery of kisspeptin's stimulatory action upon GnRH neurons. Using complimentary cell-specific knockout and knockin approaches we demonstrate here that the GnRH neuron is the key site of kisspeptin-Gpr54 signaling for fertility.

Comparative N-glycoproteomic and phosphoproteomic profiling of human placental plasma membrane between normal and preeclampsia pregnancies with high-resolution mass spectrometry

Preeclampsia is a serious complication of pregnancy, which affects 2–8% of all pregnancies and is one of the leading causes of maternal and perinatal mortality and morbidity worldwide. To better understand the molecular mechanisms involved in pathological development of placenta in preeclampsia, we used high-resolution LC-MS/MS technologies to construct a comparative N-glycoproteomic and phosphoproteomic profiling of human placental plasma membrane in normal and preeclamptic pregnancies. A total of 1027 N-glyco- and 2094 phospho- sites were detected in human placental plasma membrane, and 5 N-glyco- and 38 phospho- proteins, respectively, with differentially expression were definitively identified between control and preeclamptic placental plasma membrane. Further bioinformatics analysis indicated that these differentially expressed proteins correlate with several specific cellular processes occurring during pathological changes of preeclamptic placental plasma membrane.

Expression of kisspeptin/GPR54 and PIBF/PR in the first trimester trophoblast and decidua of women with recurrent spontaneous abortion

Kisspeptin and its receptor GPR54 play a major role in trophoblast invasion, and progesterone-induced blocking factor (PIBF) is needed for maintaining pregnancy. The expression of kisspeptin/GPR54 and PIBF/progesterone receptor (PR) in trophoblasts and deciduas and the relationship between kisspeptin and PIBF were investigated in the same women with recurrent spontaneous abortion (RSA). Trophoblastic and decidual tissues were collected from 32 RSA women who miscarried a genetically normal fetus, and 35 women who had voluntary abortion. Kisspeptin, GPR54, PIBF and PR were investigated using immunohistochemistry. Kisspeptin, GPR54 and PIBF expressions in syncytiotrophoblasts and cytotrophoblasts were decreased in RSA women as compared to controls (P<0.05). Kisspeptin, PIBF and PR expressions in deciduas were significantly decreased in RSA women as compared to controls (P<0.01). GPR54 expression in deciduas nearly showed no difference between the RSA group and the control group (P=0.958). Kisspeptin and PIBF expressions in syncytiotrophoblasts, cytotrophoblasts and deciduas were correlated with each other in the RSA group (Kappa=0.602, P=0.001; Kappa=0.590, P=0.001; Kappa=0.392, P=0.011). These data support the hypothesis that decreased kisspeptin and PIBF expressions in trophoblasts and deciduas are associated with RSA.

Comparative proteome profile of human placenta from normal and preeclamptic pregnancies

To better understand the molecular mechanisms involved in pathological development of placenta in preeclampsia, we used LC-MS/MS to construct a large-scale comparative proteome profile of human placentas from normal and preeclamptic pregnancies. A total of 2636 proteins were detected in human placentas, and 171 different proteins were definitively identified between control and preeclamptic placentas. Further bioinformatics analysis indicated that these differentially expressed proteins correlate with several specific cellular processes which occur during pathological changes of preeclamptic placenta. 6 proteins were randomly selected to verify their expression patterns with Western blotting. Of which, 3 proteins’ cellular localizations were validated with immunohistochemistry. Elucidation of how protein-expression changes coordinate the pathological development would provide researchers with a better understanding of the critical biological processes of preeclampsia and potential targets for therapeutic agents to regulate placenta function, and eventually benefit the treatment of preeclampsia.