Plasma kisspeptin levels in pregnancies with diabetes and hypertensive disease as a potential marker of placental dysfunction and adverse perinatal outcome

Kisspeptin and neurokinin B: roles in reproductive health

Kisspeptin and neurokinin B (NKB) play a key role in several physiological processes including in puberty, adult reproductive function including the menstrual cycle, as well as mediating the symptoms of menopause. Infundibular kisspeptin neurons, which coexpress NKB, regulate the activity of gonadotropin-releasing hormone (GnRH) neurons and thus the physiological pulsatile secretion of GnRH from the hypothalamus. Outside of their hypothalamic reproductive roles, these peptides are implicated in several physiological functions including sexual behavior and attraction, placental function, and bone health. Over the last two decades, research findings have considerably enhanced our understanding of the physiological regulation of the hypothalamic-pituitary-gonadal (HPG) axis and identified potential therapeutic applications. For example, recognition of the role of kisspeptin as the natural inductor of ovulation has led to research investigating its use as a safer, more physiological trigger of oocyte maturation in in vitro fertilization (IVF) treatment. Moreover, the key role of NKB in the pathophysiology of menopausal hot flashes has led to the development of pharmacological antagonism of this pathway. Indeed, fezolinetant, a neurokinin 3 receptor antagonist, has recently received Food and Drug Administration (FDA) approval for clinical use to treat menopausal vasomotor symptoms. Here, we discuss the roles of kisspeptin and NKB in human physiology, including in the regulation of puberty, menstrual cyclicity, reproductive behavior, pregnancy, menopause, and bone homeostasis. We describe how perturbations of these key physiological processes can result in disease states and consider how kisspeptin and NKB could be exploited diagnostically as well as therapeutically to treat reproductive disorders.

Kisspeptin signalling and its correlation with placental ultrastructure and clinical outcomes in pregnant South African women with obesity and gestational diabetes

INTRODUCTION

Gestational diabetes mellitus (GDM) is a major pregnancy metabolic disorder and is strongly linked with obesity. Kisspeptin is a hormone that increases several thousand-fold in the maternal circulation during human pregnancy, with placenta as its main source. Studies have suggested that kisspeptin regulates trophoblast invasion and promotes pancreatic insulin secretion and peripheral insulin sensitivity.

METHODS

In a well-characterized cohort of pregnant South African women and molecular and histological techniques, this study explored the impact and interaction of maternal obesity and GDM on kisspeptin (KISS1) signalling in relation to placental morphology and maternal and neonatal parameters.

RESULTS

We found that GDM had no effect on placental KISS1 and KISS1R (KISS1 receptor) mRNA and/or protein expression. However, obesity reduced placental KISS1R mRNA expression even though overall KISS1 protein abundance or localization was not different from the non-obese group. Maternal and cord circulating KISS1 concentrations did not vary with obesity or GDM, but maternal circulating KISS1 was positively correlated with placenta weight in non-GDM obese women, and negatively correlated with placental intervillous space volume in non-GDM non-obese women. Cord serum KISS1 was positively correlated with infant weight in GDM obese women, but negatively correlated with maternal BMI in the non-obese GDM group. Placental syncytiotrophoblast extracellular vesicles exhibited detectable KISS1 and its abundance was ∼50 % lower in those from obese GDM compared to non-GDM women.

DISCUSSION

This study shows maternal obesity and GDM can modulate placental kisspeptin signalling and placental morphological development with potential pathophysiological implications for clinically-relevant pregnancy and perinatal outcomes.

Maternal Age at Menarche Genes Determines Fetal Growth Restriction Risk

We aimed to explore the potential link of maternal age at menarche (mAAM) gene polymorphisms with risk of the fetal growth restriction (FGR). This case (FGR)-control (FGR free) study included 904 women (273 FGR and 631 control) in the third trimester of gestation examined/treated in the Departments of Obstetrics. For single nucleotide polymorphism (SNP) multiplex genotyping, 50 candidate loci of mAAM were chosen. The relationship of mAAM SNPs and FGR was appreciated by regression procedures (logistic/model-based multifactor dimensionality reduction [MB-MDR]) with subsequent in silico assessment of the assumed functionality pithy of FGR-related loci. Three mAAM-appertain loci were FGR-linked to genes such as KISS1 (rs7538038) (effect allele G-odds ratio (OR)allelic = 0.63/pperm = 0.0003; ORadditive = 0.61/pperm = 0.001; ORdominant = 0.56/pperm = 0.001), NKX2-1 (rs999460) (effect allele A-ORallelic = 1.37/pperm = 0.003; ORadditive = 1.45/pperm = 0.002; ORrecessive = 2.41/pperm = 0.0002), GPRC5B (rs12444979) (effect allele T-ORallelic = 1.67/pperm = 0.0003; ORdominant = 1.59/pperm = 0.011; ORadditive = 1.56/pperm = 0.009). The haplotype ACA FSHB gene (rs555621*rs11031010*rs1782507) was FRG-correlated (OR = 0.71/pperm = 0.05). Ten FGR-implicated interworking models were founded for 13 SNPs (pperm ≤ 0.001). The rs999460 NKX2-1 and rs12444979 GPRC5B interplays significantly influenced the FGR risk (these SNPs were present in 50% of models). FGR-related mAAM-appertain 15 polymorphic variants and 350 linked SNPs were functionally momentous in relation to 39 genes participating in the regulation of hormone levels, the ovulation cycle process, male gonad development and vitamin D metabolism. Thus, this study showed, for the first time, that the mAAM-appertain genes determine FGR risk.

Associations between maternal urinary kisspeptin in late pregnancy and decreased fetal growth: a pregnancy-birth cohort study

Background

Kisspeptin has been indicated to be a biomarker of fetal growth. Although some evidence suggested that maternal kisspeptin concentrations in early pregnancy were associated with increased fetal growth, studies are still limited and the effect of kisspeptin in late pregnancy remains unknown. This study aimed to investigate the associations between maternal kisspeptin in late pregnancy and fetal growth.

Methods

Based on the Shanghai-Minhang Birth Cohort study, 724 mother-neonate pairs were included in this study. We measured maternal kisspeptin concentrations in the urine samples collected in late pregnancy and neonatal anthropometric indices at birth. The associations between maternal kisspeptin and neonatal anthropometry were investigated using multiple linear regression models.

Results

Higher maternal urinary kisspeptin concentrations were associated with lower neonatal birth weight, head circumference, upper arm circumference, abdominal skinfold thickness, triceps skinfold thickness, and back skinfold thickness. The inverse associations were more pronounced for the highest kisspeptin levels versus the lowest. These patterns were consistent in analyses stratified by neonatal sex, with notably stable associations between maternal kisspeptin concentrations and skinfold thickness.

Conclusion

The present study suggested that maternal kisspeptin concentrations in late pregnancy might be inversely associated with fetal growth. The physiological mechanisms of maternal kisspeptin might differ from those in early pregnancy. Further studies are required to assess associations between maternal kisspeptin and energy homeostasis and explore the physiological roles of kisspeptin in late pregnancy.

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.

Kisspeptin as a predictor of miscarriage: a systematic review

OBJECTIVE

A highly accurate serum marker for predicting viable pregnancy needs to be developed. Recent studies have demonstrated that kisspeptin is a potential biomarker for this purpose.

METHODS

This systematic review evaluated the available data in the literature on the role of kisspeptin as a miscarriage biomarker. A literature search was conducted in the PubMed/Medline, Embase, Web of Science, and Scopus databases using the following keywords: (kisspeptin) AND (miscarriage OR pregnancy loss OR spontaneous abortion OR reproductive failure).

RESULTS

Seven case-control studies were selected for the systematic review. The included papers described the potential role of kisspeptin as a putative biomarker of pregnancy loss. Furthermore, two studies reported that changes in kisspeptin levels may be associated with unexplained infertility and low rates of embryo implantation in women undergoing assisted reproductive technology.

CONCLUSION

Kisspeptin might be used as a potential biomarker of pregnancy viability in the near future. However, studies with better evidence are needed to establish the applicability of kisspeptin as a diagnostic and prognostic tool.

Kisspeptin Suppresses Inflammasome-NLRP3 Activation and Pyroptosis Caused by Hypothyroidism at the Maternal-Fetal Interface of Rats

Gestational diseases such as preeclampsia and gestational diabetes cause inflammasome activation and pyroptosis in the placenta and changes in placental kisspeptin levels. Although maternal hypothyroidism also reduces the kisspeptin/Kiss1R system at the maternal-fetal interface, there is still no information on whether this dysfunction causes inflammasome activation and pyroptosis in the placenta or influences the modulatory role of kisspeptin in these processes. This study aimed to evaluate whether hypothyroidism activates the inflammasome-NLRP3 pathway and pyroptosis at the maternal-fetal interface of rats and whether kisspeptin can modulate these processes. Hypothyroidism was induced in Wistar rats by the administration of propylthiouracil. Kisspeptin-10 (Kp10) treatment began on the 8th day of gestation (DG). Gene and/or protein expressions of NLRP3, Caspase 1, IL-1β, IL-18, and Gasdermin D (Gsmd) were evaluated in the deciduae and placentae at the 18th DG. Hypothyroidism increased the decidual and placental stainings of NLRP3, IL-1β, and Gasdermin D, and increased the gene expressions of Nlrp3, Ilβ, and Il18 in the placenta and of Gsmd in the decidua. Treatment with Kp10 suppressed the increase in NLRP3/Nlrp3, IL-1β, Il18, and Gasdermin D/Gsmd caused by hypothyroidism at the maternal-fetal interface. However, Kp10 increased the placental gene expressions of Casp1 and Il1β. The findings demonstrated that maternal hypothyroidism activated the inflammasome-NLRP3 pathway and pyroptosis at the maternal-fetal interface of rats and that treatment with Kp10 was able to block these processes, thus suggesting that kisspeptin analogues may be promising in the treatment of gestational diseases that involve inflammasome activation and pyroptosis.

KISS1 Gene Variations and Susceptibility to Idiopathic Recurrent Pregnancy Loss

It is widely accepted that kisspeptin plays an integral role in the regulation of reproduction. Genetic variations in the KISS1 gene have been frequently reported to be linked to reproductive diseases, but there is still a lack of data on the association between KISS1 variations and female reproductive disorders. The present study aimed to examine the association of three missense SNPs in the KISS1 gene including rs12998, rs35431622, and rs4889 in association with idiopathic recurrent pregnancy loss (iRPL). A total of 720 individuals were recruited in this study. The DNA from the blood sample was extracted and genotyped using the PCR method. Haplotype and linkage disequilibrium (LD) have also been analyzed. The results of this study suggested that rs12998 G > A and rs4889 C > G had a significant association with iRPL (p < 0.05); while rs35431622 A > G didn't indicate any association with iRPL. A significant association was also found for three haplotypes including C-A-A, G-G-G, and G-G-A in this population. The analysis also showed a significant LD between rs12998 and rs35431622 (P < 0.0005). The rs12998 G > A and rs4889 C > G variants of KISS1 are linked to unexplained recurrent pregnancy loss and may be risk factors for this disease.

Kisspeptin and GPR54 Receptor Expression in Endometrial Cancer Tissue

Kisspeptin (KISS) is a natural peptide-discovered in 1996 as a factor inhibiting the ability to metastasize in malignant melanoma. This protein plays also a regulatory role in the process of puberty, the menstrual cycle, spermatogenesis, implantation and development of the human placenta. The present study aimed to evaluate the expression of KISS and its receptor GPR54 in endometrial cancer (EC) tissue, depending on the histological type of cancer, its stage, various demographic characteristics, and clinical conditions in 214 hysterectomy patients. Expression of KISS and GPR54 was confirmed in 99.5% and 100% of the cases, respectively. Hormone replacement therapy and the coexistence of the anti-Müllerian type 2 receptor in cancer tissue enhanced KISS expression. Smoking, on the other hand, decreased KISS expression. GPR54 expression increased with the advancement of the disease (according to FIGO classification). Also, the presence of the anti-Müllerian type 2 receptor in EC increased the level of GPR54. Hypertension, age and miscarriage harmed the presence of GPR54. The histological type of cancer, diabetes type 2, body mass index, hormonal contraception, number of deliveries, birth weight of newborns, breastfeeding time, and the presence of AMH in EC tissue were not associated with the expression of either KISS nor GPR54. The KISS level was also significantly related to the GPR54 level. Considering that KISS is a non-toxic peptide with antimetastatic properties, further investigation is essential to determine the clinical significance of this peptide.

Kisspeptin in the Prediction of Pregnancy Complications

Kisspeptin and its receptor are central to reproductive health acting as key regulators of the reproductive endocrine axis in humans. Kisspeptin is most widely recognised as a regulator of gonadotrophin releasing hormone (GnRH) neuronal function. However, recent evidence has demonstrated that kisspeptin and its receptor also play a fundamental role during pregnancy in the regulation of placentation. Kisspeptin is abundantly expressed in syncytiotrophoblasts, and its receptor in both cyto- and syncytio-trophoblasts. Circulating levels of kisspeptin rise dramatically during healthy pregnancy, which have been proposed as having potential as a biomarker of placental function. Indeed, alterations in kisspeptin levels are associated with an increased risk of adverse maternal and foetal complications. This review summarises data evaluating kisspeptin's role as a putative biomarker of pregnancy complications including miscarriage, ectopic pregnancy (EP), preterm birth (PTB), foetal growth restriction (FGR), hypertensive disorders of pregnancy (HDP), pre-eclampsia (PE), gestational diabetes mellitus (GDM), and gestational trophoblastic disease (GTD).

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.

Nano-titanium dioxide inhalation exposure during gestation drives redox dysregulation and vascular dysfunction across generations

BACKGROUND

Pregnancy is associated with many rapid biological adaptations that support healthy development of the growing fetus. One of which is critical to fetal health and development is the coordination between maternal liver derived substrates and vascular delivery. This crucial adaptation can be potentially derailed by inhalation of toxicants. Engineered nanomaterials (ENM) are commonly used in household and industrial products as well as in medicinal applications. As such, the potential risk of exposure remains a concern, especially during pregnancy. We have previously reported that ENM inhalation leads to upregulation in the production of oxidative species. Therefore, we aimed to determine if F0 dam maternal nano-TiO₂ inhalation exposure (exclusively) resulted in altered H₂O₂ production capacity and changes in downstream redox pathways in the F0 dams and subsequent F1 pups. Additionally, we investigated whether this persisted into adulthood within the F1 generation and how this impacted F1 gestational outcomes and F2 fetal health and development. We hypothesized that maternal nano-TiO₂ inhalation exposure during gestation in the F0 dams would result in upregulated H₂O₂ production in the F0 dams as well as her F1 offspring. Additionally, this toxicological insult would result in gestational vascular dysfunction in the F1 dams yielding smaller F2 generation pups.

RESULTS

Our results indicate upregulation of hepatic H₂O₂ production capacity in F0 dams, F1 offspring at 8 weeks and F1 females at gestational day 20. H₂O₂ production capacity was accompanied by a twofold increase in phosphorylation of the redox sensitive transcription factor NF-κB. In cell culture, naïve hepatocytes exposed to F1-nano-TiO₂ plasma increased H₂O₂ production. Overnight exposure of these hepatocytes to F1 plasma increased H₂O₂ production capacity in a partially NF-κB dependent manner. Pregnant F1- nano-TiO₂ females exhibited estrogen disruption (12.12 ± 3.1 pg/ml vs. 29.81 ± 8.8 pg/ml sham-control) and vascular dysfunction similar to their directly exposed mothers. F1-nano-TiO₂ uterine artery H₂O₂ production capacity was also elevated twofold. Dysfunctional gestational outcomes in the F1-nano-TiO₂ dams resulted in smaller F1 (10.22 ± 0.6 pups vs. sham-controls 12.71 ± 0.96 pups) and F2 pups (4.93 ± 0.47 g vs. 5.78 ± 0.09 g sham-control pups), and fewer F1 male pups (4.38 ± 0.3 pups vs. 6.83 ± 0.84 sham-control pups).

CONCLUSION

In conclusion, this manuscript provides critical evidence of redox dysregulation across generations following maternal ENM inhalation. Furthermore, dysfunctional gestational outcomes are observed in the F1-nano-TiO₂ generation and impact the development of F2 offspring. In total, this data provides strong initial evidence that maternal ENM exposure has robust biological impacts that persists in at least two generations.

Metabolic actions of kisspeptin signaling: Effects on body weight, energy expenditure, and feeding

Kisspeptin (encoded by the Kiss1 gene) and its receptor, KISS1R (encoded by the Kiss1r gene), have well-established roles in stimulating reproduction via central actions on reproductive neural circuits, but recent evidence suggests that kisspeptin signaling also influences metabolism and energy balance. Indeed, both Kiss1 and Kiss1r are expressed in many metabolically-relevant peripheral tissues, including both white and brown adipose tissue, the liver, and the pancreas, suggesting possible actions on these tissues or involvement in their physiology. In addition, there may be central actions of kisspeptin signaling, or factors co-released from kisspeptin neurons, that modulate metabolic, feeding, or thermoregulatory processes. Accumulating data from animal models suggests that kisspeptin signaling regulates a wide variety of metabolic parameters, including body weight and energy expenditure, adiposity and adipose tissue function, food intake, glucose metabolism, respiratory rates, locomotor activity, and thermoregulation. Herein, the current evidence for the involvement of kisspeptin signaling in each of these physiological parameters is reviewed, gaps in knowledge identified, and future avenues of important research highlighted. Collectively, the discussed findings highlight emerging non-reproductive actions of kisspeptin signaling in metabolism and energy balance, in addition to previously documented roles in reproductive control, but also emphasize the need for more research to resolve current controversies and uncover underlying molecular and physiological mechanisms.

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

BACKGROUND

Tightly regulation of extravillous cytotrophoblast (EVT) cell invasion is critical for the placentation and establishment of a successful pregnancy. Insufficient EVT cell invasion leads to the development of preeclampsia (PE) which is a leading cause of maternal and perinatal mortality and morbidity. Transforming growth factor-beta1 (TGF-β1) and kisspeptin are expressed in the human placenta and have been shown to inhibit EVT cell invasion. Kisspeptin is a downstream target of TGF-β1 in human breast cancer cells. However, whether kisspeptin is regulated by TGF-β1 and mediates TGF-β1-suppressed human EVT cell invasion remains unclear.

METHODS

The effect of TGF-β1 on kisspeptin expression and the underlying mechanisms were explored by a series of in vitro experiments in a human EVT cell line, HTR-8/SVneo, and primary cultures of human EVT cells. Serum levels of TGF-β1 and kisspeptin in patients with or without PE were measured by ELISA.

RESULTS

TGF-β1 upregulates kisspeptin expression in HTR-8/SVneo cells and primary cultures of human EVT cells. Using pharmacological inhibitor and siRNA, we demonstrate that the stimulatory effect of TGF-β1 on kisspeptin expression is mediated via the ALK5 receptor. Treatment with TGF-β1 activates SMAD2/3 canonical pathways as well as ERK1/2 and PI3K/AKT non-canonical pathways. However, only inhibition of ERK1/2 activation attenuates the stimulatory effect of TGF-β1 on kisspeptin expression. In addition, siRNA-mediated knockdown of kisspeptin attenuated TGF-β1-suppressed EVT cell invasion. Moreover, we report that serum levels of TGF-β1 and kisspeptin are significantly upregulated in patients with PE.

CONCLUSIONS

By illustrating the potential physiological role of TGF-β1 in the regulation of kisspeptin expression, our results may serve to improve current strategies used to treat placental diseases.

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.

Preeclampsia and gestational hypertension are associated to low maternal circulating kisspeptin levels: a systematic review and meta-analysis

BACKGROUND

There are contradictory data concerning kisspeptin in gravids with preeclampsia and gestational hypertension (GH).

OBJECTIVE

To conduct a meta-analysis of studies comparing maternal kisspeptin levels in gravids with and without preeclampsia or GH.

MATERIAL AND METHODS

We searched PubMed, LILACS, and CNKI list of articles up to 20 August 2021, without language limitations, comparing circulating maternal kisspeptin levels, and maternal and neonatal outcomes in gravids with and without preeclampsia or GH. Meta-analyzed results are reported as standardized mean differences (SMD), and their 95% confidence interval (CI).

RESULTS

Seven studies with a low-to-moderate risk of bias were eligible for meta-analysis. Gravids with preeclampsia or GH displayed significantly lower circulating kisspeptin levels (SMD, -0.68, 95% CI, -1.04 to -0.32), lower gestational ages at delivery (SMD, -2.22, 95% CI, -3.25 to -1.18), and birth weight (SMD, -2.16, 95% CI, -3.15 to -1.17), and significantly higher body mass indices (MD, 0.56, 95% CI, 0.24-0.88), systolic (SMD, 2.87, 95% CI, 2.22-3.53), and diastolic blood pressures (SMD, 2.57, 95% CI, 2.19-2.95).

CONCLUSION

Gravids with preeclampsia or GH had lower kisspeptin levels as compared to normotensive controls.

EGF stimulates human trophoblast cell invasion by downregulating ID3-mediated KISS1 expression

Background

During pregnancy, trophoblast cell invasion needs to be finely controlled. Aberrant trophoblast cell invasion is associated with placental diseases. Epidermal growth factor (EGF) and its receptor, EGFR, are expressed in trophoblast cells. Although the pro-invasive effect of EGF on trophoblast cells has been reported, the underlying mechanism remains largely unknown.

Results

In the present study, we conducted an RNA sequencing (RNA-seq) to HTR-8/SVneo human trophoblast cells in response to EGF and identified KISS1 as a target gene of EGF. The human KISS1 gene encodes kisspeptin, also known as metastin, which can suppress tumor metastasis. Our results showed that EGF treatment downregulated KISS1 expression and secretion by activating the EGFR-mediated PI3K/AKT signaling pathway. In addition, the expression of inhibitor of DNA-binding protein 3 (ID3) was downregulated by EGF and that was required for the EGF-suppressed KISS1 expression. Functionally, transwell invasion assays demonstrated that EGF stimulated human trophoblast cell invasion by downregulating KISS1 expression. Preeclampsia (PE) is a placental disease characterized by insufficient trophoblast cell invasion. Our clinical results revealed that serum levels of EGF were downregulated while serum and placental levels of KISS1 were upregulated in PE patients.

Conclusions

This study demonstrates that downregulation of EGF can lead to poor trophoblast cell invasion by increasing KISS1 expression which subsequently contributes to the pathogenesis of PE.

Emerging roles of kisspeptin/galanin in age-related metabolic disease

Age is a major risk factor for developing metabolic diseases such as obesity and diabetes. There is an unprecedented rise in obesity and type 2 diabetes in recent decades. A convincing majority of brain-gut peptides are associated with a higher risk to develop metabolic disorders, and may contribute to the pathophysiology of age-related metabolic diseases. Accumulating basic studies revealed an intriguing role of kisspeptin and galanin involved in the amelioration of insulin resistance in different ways. In patients suffered from obesity and diabetes a significant, sex-related changes in the plasma kisspeptin and galanin levels occurred. Kisspeptin is anorexigenic to prevent obesity, its level is negatively correlative with obesity and insulin resistance. While galanin is appetitive to stimulate food intake and body weight, its level is positively correlative with obesity, HOMA-IR and glucose/triglyceride concentration. In turn, kisspeptin and galanin also distinctly increase glucose uptake and utilization as well as energy expenditure. This article reviews recent evidence dealing with the role of kisspeptin and galanin in the pathophysiology of age-related metabolic diseases. It should be therefore taken into account that the targeted modulation of those peptidergic signaling may be potentially helpful in the future treatment of age-related metabolic diseases.

Investigation of the usability of kisspeptin and oxidative stress parameters in the early diagnosis of asymptomatic cystic endometrial hyperplasia in dogs

This study aimed to investigate the differences in oxidative stress index (OSI) and kisspeptin levels in clinically asymptomatic dogs with cystic endometrial hyperplasia (CEH) compared to healthy and pregnant dogs, and to determine the usability of the obtained results in the diagnosis of asymptomatic CEH. The study comprised three groups; a healthy (n = 8), a pregnant (n = 10) and a CEH (n = 10). All dogs in the three groups were included in the study at the 30 ± 3th day after estrus, and blood samples were collected for analysis of kisspeptin, total antioxidant status (TAS), total oxidant status (TOS), progesterone (P4), estradiol (E2) and some biochemical parameters (TSH; thyroid stimulating hormone, ALT; alanine aminotransferase, AST; aspartate aminotransferase, ALP; alkaline phosphatase, LDH; lactate dehydrogenase, CRE; creatine and BUN; blood urea nitrogen). In addition, OSI value was calculated. P4 and ALT and BUN levels were significantly lower and higher in CEH group than the pregnant group, respectively (p < .05). While kisspeptin and TAS levels were significantly lower in CEH group compared to the healthy and pregnant groups (p < .01), OSI level increased dramatically. In conclusion, it was confirmed that CEH clearly affected kisspeptin and OSI levels, and it is thought that these parameters may be an alternative diagnostic tool for the detection of CEH after further studies.

Kisspeptin and Hematologic Parameters as Predictive Biomarkers for First-Trimester Abortions

Objective

Spontaneous abortion is the most common complication of early pregnancy, affecting up to 20% of recognized pregnancies. Kisspeptin is predominantly released by placental syncytiotrophoblasts, and regulates their placental invasion into the uterine matrices. We aimed to establish an association of serum kisspeptin levels with pregnancy outcomes during the early gestational stage of the first trimester.

Method

In this prospective study, 90 pregnant women in their 7 to 8 6/7 gestational weeks were classified into three groups: (i) The control group, consisting of healthy pregnant women (n=30), (ii) the threatened abortion group (n=30), and (iii) the spontaneous abortion group (n=30). The maternal serum samples were analyzed for complete blood count parameters and kisspeptin levels.

Results

There was no statistical difference regarding body mass index (BMI) and gestational age (p=0.370). Regarding detailed obstetric notations, including gravida, parity, abortion, and living children, socioeconomic levels, and employment rates, all study groups were comparable (p>0.05, for all). No significant association was found regarding the biochemical parameters of complete blood count, including neutrophil, lymphocyte, and platelet concentrations, as well as neutrophil-to-lymphocyte ratios (NLR) and platelet-to-lymphocyte ratios (PLR) (p>0.05, for all). The median serum kisspeptin levels of the study groups did not differ between the groups (p=0.153). Correlation analysis revealed no significant relationship between serum kisspeptin levels and other study parameters in any study groups (p>0.05, for all)

Conclusion

We found no statistically significant relationship between serum kisspeptin concentrations and pregnancy outcomes in the early gestational stage of the first trimester, and serum kisspeptin concentrations did not seem to be a reliable marker to distinguish abortion status from viable pregnancy.

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.

From inhibition of trophoblast cell invasion to proapoptosis: what are the potential roles of kisspeptins in preeclampsia?

Preeclampsia (PE) is a life-threatening human gestational syndrome with incompletely understood etiopathogenesis. The disorder has a spectrum of clinical features, likely due to a complex interaction between maternal predisposing factors and abnormalities at the maternal-fetal interface. Poor trophoblast cell invasion, inadequate uterine vascular remodeling, and placental hypoperfusion are considered as key placental events leading to PE. Kisspeptins, a family of small peptides derived from the KISS1 gene, have been implicated in the development of this syndrome. Most studies of kisspeptin expression in PE have reported an upregulation of kisspeptins and/or their cognate receptor in preeclamptic placentas. Conversely, maternal peripheral blood concentration of kisspeptins is reportedly lower in PE than in uncomplicated pregnancies. This apparent paradox remains to be further elucidated. Although kisspeptins were initially known for inhibiting cellular migration and invasion, other biological activities attributed to these peptides include neuroendocrine regulation of reproduction, metabolism regulation, inhibition of angiogenesis, and induction of apoptosis. This review summarizes the current knowledge on expression and biological activity of kisspeptins at the maternal-fetal interface in the context of PE.

Functions of galanin, spexin and kisspeptin in metabolism, mood and behaviour

The bioactive peptides galanin, spexin and kisspeptin have a common ancestral origin and their pathophysiological roles are increasingly the subject of investigation. Evidence suggests that these bioactive peptides play a role in the regulation of metabolism, pancreatic β-cell function, energy homeostasis, mood and behaviour in several species, including zebrafish, rodents and humans. Galanin signalling suppresses insulin secretion in animal models (but not in humans), is potently obesogenic and plays putative roles governing certain evolutionary behaviours and mood modulation. Spexin decreases insulin secretion and has potent anorectic, analgesic, anxiolytic and antidepressive-like effects in animal models. Kisspeptin modulates glucose-stimulated insulin secretion, food intake and/or energy expenditure in animal models and humans. Furthermore, kisspeptin is implicated in the control of reproductive behaviour in animals, modulation of human sexual and emotional brain processing, and has antidepressive and fear-suppressing effects. In addition, galanin-like peptide is a further member of the galaninergic family that plays emerging key roles in metabolism and behaviour. Therapeutic interventions targeting galanin, spexin and/or kisspeptin signalling pathways could therefore contribute to the treatment of conditions ranging from obesity to mood disorders. However, many gaps and controversies exist, which must be addressed before the therapeutic potential of these bioactive peptides can be established.

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.

Roles of the kisspeptin/GPR54 system in pathomechanisms of atherosclerosis

AIMS

Kisspeptin-10 (KP-10), a potent vasoconstrictor and inhibitor of angiogenesis, and its receptor, GPR54, have currently received much attention with respect to atherosclerosis, since both KP-10 and GPR54 are expressed at high levels in atheromatous plaques and restenotic lesions after wire-injury. The present review introduces the emerging roles of the KP-10/GPR54 system in atherosclerosis.

DATA SYNTHESIS

KP-10 suppresses migration and proliferation of human umbilical vein endothelial cells (HUVECs), and induces senescence in HUVECs. KP-10 increases adhesion of human monocytes to HUVECs. KP-10 also stimulates expression of interleukin-6, tumor necrosis factor-α, monocyte chemotactic protein-1, intercellular adhesion molecule-1, vascular cell adhesion molecule-1, and E-selectin genes in HUVECs. KP-10 enhances oxidized low-density lipoprotein-induced foam cell formation associated with upregulation of CD36 and acyl-coenzyme A: cholesterol acyltransferase-1 in human monocyte-derived macrophages. In human aortic smooth muscle cells, KP-10 suppresses angiotensin II-induced migration and proliferation, however, it enhances apoptosis and activities of matrix metalloproteinase (MMP)-2 and MMP-9 by upregulation of extracellular signal-regulated kinase 1/2, p38, Bax, and caspase-3. Four-week-infusion of KP-10 into Apoe^-/- mice accelerates development of aortic atherosclerotic lesions with increased monocyte/macrophage infiltration and vascular inflammation, also, it decreases intraplaque vascular smooth muscle cell content. Proatherosclerotic effects of endogenous and exogenous KP-10 were completely attenuated upon infusion of P234, a GPR54 antagonist, in Apoe^-/- mice.

CONCLUSION

These findings suggest that KP-10 may contribute to acceleration of progression and to the instability of atheromatous plaques, leading to rupture of plaques. This GPR54 antagonist may be useful for the prevention and treatment of atherosclerosis. Thus, the KP-10/GPR54 system may serve as a novel therapeutic target for atherosclerotic diseases.

Potential roles for the kisspeptin/kisspeptin receptor system in implantation and placentation

BACKGROUND

Initially identified as suppressors of metastasis in various types of cancer, kisspeptins are a family of neuropeptides that are key regulators of the mammalian reproductive axis. Accumulating evidence has shown that kisspeptin is able to control both the pulsatile and surge GnRH release, playing fundamental roles in female reproduction, which include the secretion of gonadotropins, puberty onset, brain sex differentiation, ovulation and the metabolic regulation of fertility. Furthermore, recent studies have demonstrated the involvement of the kisspeptin system in the processes of implantation and placentation. This review summarizes the current knowledge of the pathophysiological role and utility of these local placental regulatory factors as potential biomarkers during the early human gestation.

OBJECTIVE AND RATIONALE

A successful pregnancy, from the initiation of embryo implantation to parturition, is a complex process that requires the orchestration of a series of events. This review aims to concisely summarize what is known about the role of the kisspeptin system in implantation, placentation, early human pregnancy and pregnancy-related disorders, and to develop strategies for predicting, diagnosing and treating these abnormalities.

SEARCH METHODS

Using the PubMed and Google Scholar databases, we performed comprehensive literature searches in the English language describing the advancement of kisspeptins and the kisspeptin receptor (KISS1R) in implantation, placentation and early pregnancy in humans, since its initial identification in 1996 and ending in July 2018.

OUTCOMES

Recent studies have shown the coordinated spatial and temporal expression patterns of kisspeptins and KISS1R during human pregnancy. The experimental data gathered recently suggest putative roles of kisspeptin signaling in the regulation of trophoblast invasion, embryo implantation, placentation and early pregnancy. Dysregulation of the kisspeptin system may negatively affect the processes of implantation as well as placentation. Clinical studies indicate that the circulating levels of kisspeptins or the expression levels of kisspeptin/KISS1R in the placental tissues may be used as potential diagnostic markers for women with miscarriage and gestational trophoblastic neoplasia.

WIDER IMPLICATIONS

Comprehensive research on the pathophysiological role of the kisspeptin/KISS1R system in implantation and placentation will provide a dynamic and powerful approach to understanding the processes of early pregnancy, with potential applications in observational and analytic screening as well as the diagnosis, prognosis and treatment of implantation failure and early pregnancy-related disorders.

Maternal Engineered Nanomaterial Inhalation During Gestation Disrupts Vascular Kisspeptin Reactivity

Maternal engineered nanomaterial (ENM) inhalation is associated with uterine vascular impairments and endocrine disruption that may lead to altered gestational outcomes. We have shown that nano-titanium dioxide (nano-TiO2) inhalation impairs endothelium-dependent uterine arteriolar dilation in pregnant rats. However, the mechanism underlying this dysfunction is unknown. Due to its role as a potent vasoconstrictor and essential reproductive hormone, we examined how kisspeptin is involved in nano-TiO2-induced vascular dysfunction and placental efficiency. Pregnant Sprague Dawley rats were exposed (gestational day [GD] 10) to nano-TiO2 aerosols (cumulative dose = 525 ± 16 μg; n = 8) or sham exposed (n = 6) and sacrificed on GD 20. Plasma was collected to evaluate estrogen (E2), progesterone (P4), prolactin (PRL), corticosterone (CORT), and kisspeptin. Pup and placental weights were measured to calculate placental efficiency (grams fetus/gram placental). Additionally, pressure myography was used to determine uterine artery vascular reactivity. Contractile responses were assessed via cumulative additions of kisspeptin (1 × 10-9 to 1 × 10-4 M). Estrogen was decreased at GD 20 in exposed (11.08 ± 3 pg/ml) versus sham-control rats (66.97 ± 3 pg/ml), whereas there were no differences in P4, PRL, CORT, or kisspeptin. Placental weights were increased in exposed (0.99 ± 0.03 g) versus sham-control rats (0.70 ± 0.04 g), whereas pup weights (4.01 ± 0.47 g vs 4.15 ± 0.15 g) and placental efficiency (4.5 ± 0.2 vs 6.4 ± 0.5) were decreased in exposed rats. Maternal ENM inhalation exposure augmented uterine artery vasoconstrictor responses to kisspeptin (91.2%±2.0 vs 98.6%±0.10). These studies represent initial evidence that pulmonary maternal ENM exposure perturbs the normal gestational endocrine vascular axis via a kisspeptin-dependent mechanism, and decreased placental, which may adversely affect health outcomes.

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.

A role for placental kisspeptin in β cell adaptation to pregnancy

During pregnancy the maternal pancreatic islets of Langerhans undergo adaptive changes to compensate for gestational insulin resistance. Kisspeptin has been shown to stimulate insulin release, through its receptor, GPR54. The placenta releases high levels of kisspeptin into the maternal circulation, suggesting a role in modulating the islet adaptation to pregnancy. In the present study we show that pharmacological blockade of endogenous kisspeptin in pregnant mice resulted in impaired glucose homeostasis. This glucose intolerance was due to a reduced insulin response to glucose as opposed to any effect on insulin sensitivity. A β cell–specific GPR54-knockdown mouse line was found to exhibit glucose intolerance during pregnancy, with no phenotype observed outside of pregnancy. Furthermore, in pregnant women circulating kisspeptin levels significantly correlated with insulin responses to oral glucose challenge and were significantly lower in women with gestational diabetes (GDM) compared with those without GDM. Thus, kisspeptin represents a placental signal that plays a physiological role in the islet adaptation to pregnancy, maintaining maternal glucose homeostasis by acting through the β cell GPR54 receptor. Our data suggest reduced placental kisspeptin production, with consequent impaired kisspeptin-dependent β cell compensation, may be a factor in the development of GDM in humans.

Placental kisspeptin regulates islet adaptation to pregnancy that is necessary for preventing gestational diabetes in mice and humans.

Kisspeptin as a potential biomarker throughout pregnancy

Kisspeptins are a family of neuropeptides that are critical for the puberty initiation and female fertility. Plasma or serum kisspeptin is mainly derived from the placenta during pregnancy and plasma kisspeptin levels significantly increase across pregnancy. Plasma kisspeptin levels could be used as a potential biomarker for the detection of miscarriage, pre-eclampsia, gestational trophoblastic neoplasia (GTN), and fetal development. Kisspeptin may also be involved in the process of parturition by stimulating oxytocin secretion during term pregnancy. This review discussed the potential use of kisspeptin as a marker across pregnancy and highlighted the unresolved problems in this area. Tweetable abstract: Plasma kisspeptin levels could be used as a potential biomarker across pregnancy.

Kisspeptin‑13 inhibits bleomycin‑induced pulmonary fibrosis through GPR54 in mice

Kisspeptin (KP) is an amidated neurohormone that is encoded by the KiSS-1 metastasis suppressor (KISS1) gene and serves as the endogenous ligand for G protein-coupled receptor 54 (GPR54). KP is involved in the regulation of several biological functions, such as reproduction, cancer and atherogenesis. Recent data suggested that KP may induce atherosclerotic plaque progression and instability, which may be reversed by the GPR54 antagonist KP-234. Despite the KISS1 gene being previously reported as a downstream target of the classic transforming growth factor (TGF)/Smad2 signaling pathway, its role in fibrosis remains elusive. The purpose of the present study was to evaluate the role of KP-13 (a product of the KISS1 gene) in a bleomycin (BLM)-induced idiopathic pulmonary fibrosis model. Lung tissue samples were evaluated by quantitative PCR analysis, western blotting and ELISA. Daily intraperitoneal administration of KP-13 significantly ameliorated body weight loss, histopathological lung abnormalities and pulmonary collagen deposition induced by BLM. Furthermore, KP-13 downregulated the expression levels of tumor necrosis factor-α, TGF-β, collagen type I α1, actin α2 and matrix metalloproteinase 2 in BLM-treated lungs compared with BLM group. Notably, the production of α-smooth muscle actin in lung tissues, as well as the pulmonary levels of TGF-β1 and phosphorylated-Smad2/3, was reduced following treatment with KP-13. The anti-fibrotic effects of KP-13 were reversed by KP-234 (an antagonist of GPR54), but not by Cetrorelix (an antagonist of the gonadotropin-releasing hormone receptor). Furthermore, apoptosis-related proteins, such as Bax and caspase-3, were decreased, whereas Bcl-2 was markedly increased as determined by western blotting. Collectively, these data suggested that the KP/GPR54 signaling pathway may be a promising target for the treatment of idiopathic pulmonary fibrosis.

The effects of kisspeptin on β-cell function, serum metabolites and appetite in humans

AIMS

To investigate the effect of kisspeptin on glucose-stimulated insulin secretion and appetite in humans.

MATERIALS AND METHODS

In 15 healthy men (age: 25.2 ± 1.1 years; BMI: 22.3 ± 0.5 kg m-2 ), we compared the effects of 1 nmol kg-1 h-1 kisspeptin versus vehicle administration on glucose-stimulated insulin secretion, metabolites, gut hormones, appetite and food intake. In addition, we assessed the effect of kisspeptin on glucose-stimulated insulin secretion in vitro in human pancreatic islets and a human β-cell line (EndoC-βH1 cells).

RESULTS

Kisspeptin administration to healthy men enhanced insulin secretion following an intravenous glucose load, and modulated serum metabolites. In keeping with this, kisspeptin increased glucose-stimulated insulin secretion from human islets and a human pancreatic cell line in vitro. In addition, kisspeptin administration did not alter gut hormones, appetite or food intake in healthy men.

CONCLUSIONS

Collectively, these data demonstrate for the first time a beneficial role for kisspeptin in insulin secretion in humans in vivo. This has important implications for our understanding of the links between reproduction and metabolism in humans, as well as for the ongoing translational development of kisspeptin-based therapies for reproductive and potentially metabolic conditions.

Inverted pyramid of prenatal care - is it enough? Should it be - extended inverted pyramid of prenatal care?

In recent years, the idea of the inverted pyramid of prenatal care and monitoring has emerged, for the purpose of prediction and prevention, early detection and treatment of health disorders of the fetus. Is this enough? If we analyze the period behind us, progress has been made in the field of detection of multiple pregnancies, dating of pregnancy and prenatal detection of chromosomal and structural fetal disorders, as well as a small amount of progress in terms of prediction and prevention of preeclampsia. If these disorders are the consequence of the disturbed or dysfunctional placentation, they are rooted at the time of implantation. This means that the changes that lead to the dysfunctional implantation should be sought in the pre-implantation period, in relation between the embryo and the endometrium. An extended inverted pyramid is necessary to find better results in perinatal medicine. This means that the interventions should be focused on the preconception and peri-implantation periods. The therapy should be on the subcellular and genetic level by applying the latest biotechnological procedures. It is possible that the time is approaching when the listed disorders of a pregnancy will be the indications for the application of a non stimulated in-vitro fertilization (IVF) (without ovary stimulating medication) with the use of new biotechnological achievements.

The Role of Placental Hormones in Mediating Maternal Adaptations to Support Pregnancy and Lactation

During pregnancy, the mother must adapt her body systems to support nutrient and oxygen supply for growth of the baby in utero and during the subsequent lactation. These include changes in the cardiovascular, pulmonary, immune and metabolic systems of the mother. Failure to appropriately adjust maternal physiology to the pregnant state may result in pregnancy complications, including gestational diabetes and abnormal birth weight, which can further lead to a range of medically significant complications for the mother and baby. The placenta, which forms the functional interface separating the maternal and fetal circulations, is important for mediating adaptations in maternal physiology. It secretes a plethora of hormones into the maternal circulation which modulate her physiology and transfers the oxygen and nutrients available to the fetus for growth. Among these placental hormones, the prolactin-growth hormone family, steroids and neuropeptides play critical roles in driving maternal physiological adaptations during pregnancy. This review examines the changes that occur in maternal physiology in response to pregnancy and the significance of placental hormone production in mediating such changes.

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.

The role of kisspeptin and RFRP in the circadian control of female reproduction

In female mammals, reproduction shows ovarian and daily rhythms ensuring that the timing of the greatest fertility coincides with maximal activity and arousal. The ovarian cycle, which lasts from a few days to a few weeks, depends on the rhythm of follicle maturation and ovarian hormone production, whereas the daily cycle depends on a network of circadian clocks of which the main one is located in the suprachiasmatic nuclei (SCN). In the last ten years, major progress has been made in the understanding of the neuronal mechanisms governing mammalian reproduction with the finding that two hypothalamic Arg-Phe-amide peptides, kisspeptin (Kp) and RFRP, regulate GnRH neurons. In this review we discuss the pivotal role of Kp and RFRP neurons at the interface between the SCN clock signal and GnRH neurons to properly time gonadotropin-induced ovulation. We also report recent findings indicating that these neurons may be part of the multi-oscillatory circadian system that times female fertility. Finally, we will discuss recent investigations indicating a role, and putative therapeutic use, of these neuropeptides in human reproduction.

Kisspeptin across the human lifespan:evidence from animal studies and beyond

Since its first description in 1996, the KISS1 gene and its peptide products, kisspeptins, have increasingly become recognised as key regulators of reproductive health. With kisspeptins acting as ligands for the kisspeptin receptor KISS1R (previously known as GPR54 or KPR54), recent work has consistently shown that administration of kisspeptin across a variety of species stimulates gonadotrophin release through influencing gonadotrophin-releasing hormone secretion. Evidence from both animal and human studies supports the finding that kisspeptins are crucial for ensuring healthy development, with knockout animal models, as well as proband genetic testing in human patients affected by abnormal pubertal development, corroborating the notion that a functional kisspeptin receptor is required for appropriate gonadotrophin secretion. Given the large body of evidence that exists surrounding the influence of kisspeptin in a variety of settings, this review summarises our physiological understanding of the role of these important peptides and their receptors, before proceeding to describe the varying role they play across the reproductive lifespan.

There is Kisspeptin - And Then There is Kisspeptin

While kisspeptin was initially found to function as a metastasis suppressor, after identification of its receptor KISS1R and their expression profiles in tissues such as the hypothalamus and adrenals, kisspeptin and KISS1R were predominantly assigned endocrine functions, including regulating puberty and fertility through their actions on hypothalamic gonadotropin releasing hormone production. More recently, an alter ego for kisspeptin has emerged, with a significant role in regulating glucose homeostasis, insulin secretion, as well as food intake and body composition, and deficient kisspeptin signaling results in reduced locomotor activity and increased adiposity. This review highlights these recent observations on the role of kisspeptin in metabolism as well as several key questions that need to be addressed in the future.

Comprehensive Review on Kisspeptin and Its Role in Reproductive Disorders

Kisspeptin has recently emerged as a key regulator of the mammalian reproductive axis. It is known that kisspeptin, acting centrally via the kisspeptin receptor, stimulates secretion of gonadotrophin releasing hormone (GnRH). Loss of kisspeptin signaling causes hypogonadotrophic hypogonadism in humans and other mammals. Kisspeptin interacts with other neuropeptides such as neurokinin B and dynorphin, to regulate GnRH pulse generation. In addition, a growing body of evidence suggests that kisspeptin signaling be regulated by nutritional status and stress. Kisspeptin may also represent a novel potential therapeutic target in the treatment of fertility disorders. Early human studies suggest that peripheral exogenous kisspeptin administration stimulates gonadotrophin release in healthy adults and in patients with certain forms of infertility. This review aims to concisely summarize what is known about kisspeptin as a regulator of reproductive function, and provide an update on recent advances within this field.

Potential Clinical Use of Kisspeptin

Over the last 10 years, kisspeptins--peptide products of varying lengths encoded by the KISS1 gene--have been found to be key regulators of normal reproductive function throughout life in animals and humans. By activating the kisspeptin receptor [previously known as orphan G protein-coupled receptor 54 (GPR54)], they elicit an effect on the central gonadotropin-releasing hormone neurons. Administration of kisspeptin by either the subcutaneous or intravenous route potently stimulates endogenous gonadotropin hormone release in healthy men and women as well as in animals. Kisspeptin also stimulates endogenous release of gonadotropins in subfertile as well as healthy volunteers, and therefore it has potential as a novel therapeutic agent in reproductive disorders. Further human studies have shown that chronic, high-dose administration of kisspeptin causes desensitisation with rapid subsequent suppression of the hypothalamic-pituitary-gonadal axis, and therefore high-dose long-acting analogues may have a clinical role in treating sex hormone-dependent malignancies. By further elucidating the intricacies and mechanisms of the kisspeptin signalling system, and the tissues it acts on during different phases of the reproductive timeline (including during puberty, fertility, pregnancy and menopause), pharmacologic analogues could become clinically useful.

Glucagon regulates hepatic kisspeptin to impair insulin secretion

Early in the pathogenesis of type 2 diabetes mellitus (T2DM), dysregulated glucagon secretion from pancreatic α cells occurs prior to impaired glucose-stimulated insulin secretion (GSIS) from β cells. However, whether hyperglucagonemia is causally linked to β cell dysfunction remains unclear. Here we show that glucagon stimulates via cAMP-PKA-CREB signaling hepatic production of the neuropeptide kisspeptin1, which acts on β cells to suppress GSIS. Synthetic kisspeptin suppresses GSIS in vivo in mice and from isolated islets in a kisspeptin1 receptor-dependent manner. Kisspeptin1 is increased in livers and in serum from humans with T2DM and from mouse models of diabetes mellitus. Importantly, liver Kiss1 knockdown in hyperglucagonemic, glucose-intolerant, high-fat-diet fed, and Lepr(db/db) mice augments GSIS and improves glucose tolerance. These observations indicate a hormonal circuit between the liver and the endocrine pancreas in glycemia regulation and suggest in T2DM a sequential link between hyperglucagonemia via hepatic kisspeptin1 to impaired insulin secretion.