Human chorionic gonadotrophin indirectly activates peripheral γδT cells to produce interleukin-10 during early pregnancy

BACKGROUNDS

The immunomodulatory properties of human chorionic gonadotrophin (hCG) have been identified to be critical for successful pregnancy. However, the effects of hCG on peripheral γδT cells during early pregnancy have not been reported previously.

METHODS

We cocultured the purified γδT cells and peripheral blood mononuclear cells (PBMCs) with early pregnancy-relevant hCG concentrations and investigated the changes in the immune functional characteristics of γδT cells via flow cytometry assays.

RESULTS

The ratios of CD69+ and IL-10+ γδT cells were increased in early pregnant women compared to nonpregnant women. γδT cells expressed low levels of the mannose receptor (CD206) instead of the classical hCG/LH receptor for hCG. The direct treatment of purified γδT cells with early pregnancy-relevant hCG concentrations may have no significant effects on their immune functions. Interestingly, when PBMCs were treated with the same broad range of hCG concentrations, the ratios of CD69+ and IL-10+ γδT cells to total γδT cells were significantly increased.

CONCLUSION

Certain early pregnancy-relevant hCG concentrations could enhance the ratios of peripheral CD69+ and IL-10+ γδT cells, contributing to the activation of γδT cells and immunological tolerance during early pregnancy. However, these affects may not be strongly mediated by direct ligand-receptor interactions and they may highly depend on immune microenvironment. Our novel observations propose a perspective into the endocrine-immune dialog that exists between the fetus and maternal immune cells.

Human chorionic gonadotropin promotes murine Treg cells and restricts pregnancy-harmful proinflammatory Th17 responses

An equilibrium between proinflammatory and anti-inflammatory immune responses is essential for maternal tolerance of the fetus throughout gestation. To study the participation of fetal tissue-derived factors in this delicate immune balance, we analyzed the effects of human chorionic gonadotropin (hCG) on murine Treg cells and Th17 cells in vitro, and on pregnancy outcomes, fetal and placental growth, blood flow velocities and remodeling of the uterine vascular bed in vivo. Compared with untreated CD4⁺CD25⁺ T cells, hCG increased the frequency of Treg cells upon activation of the LH/CG receptor. hCG, with the involvement of IL-2, also interfered with induced differentiation of CD4⁺ T cells into proinflammatory Th17 cells. In already differentiated Th17 cells, hCG induced an anti-inflammatory profile. Transfer of proinflammatory Th17 cells into healthy pregnant mice promoted fetal rejection, impaired fetal growth and resulted in insufficient remodeling of uterine spiral arteries, and abnormal flow velocities. Our works show that proinflammatory Th17 cells have a negative influence on pregnancy that can be partly avoided by in vitro re-programming of proinflammatory Th17 cells with hCG.

Human Chorionic Gonadotrophin: New Pleiotropic Functions for an "Old" Hormone During Pregnancy

Human chorionic gonadotrophin (hCG) is the first specific molecule synthesized by the embryo. hCG RNA is transcribed as early as the eight-cell stage, and the blastocyst produces the protein before its implantation. hCG in the uterine microenvironment binds with its cognate receptor, luteinizing hormone/choriogonadotropin receptor (LHCGR), on the endometrial surface. This binding stimulates leukemia inhibitory factor (LIF) production and inhibits interleukin-6 (IL-6) production by epithelial cells of the endometrium. These effects ensure essential help in the preparation of the endometrium for initial embryo implantation. hCG also effects angiogenic and immunomodulatory actions as reported in many articles by our laboratories and other ones. By stimulating angiogenesis and vasculogenesis, hCG provides the placenta with an adequate maternal blood supply and optimal embryo nutrition during the invasion of the uterine endometrium. The immunomodulatory properties of hCG are numerous and important for programming maternal immune tolerance toward the embryo. The reported effects of hCG on uterine NK, Treg, and B cells, three major cell populations for the maintenance of pregnancy, demonstrate the role of this embryonic signal as a crucial immune regulator in the course of pregnancy. Human embryo rejection for hCG-related immunological reasons has been studied in different ways, and a sufficient dose of hCG seems to be necessary to maintain maternal tolerance. Different teams have studied the addition of hCG in patients suffering from recurrent miscarriages or implantation failures. hCG could also have a beneficial or a negative impact on autoimmune diseases during pregnancy. In this review, we will discuss the immunological impacts of hCG during pregnancy and if this hormone might be used therapeutically.

The Role of HCG in Implantation: A Mini-Review of Molecular and Clinical Evidence

Embryo implantation is a complex process involving continuous molecular cross-talk between the embryo and the decidua. One of the key molecules during this process is human chorionic gonadotropin (HCG). HCG effectively modulates several metabolic pathways within the decidua contributing to endometrial receptivity. Herein, a brief overview of the molecular mechanisms regulated by HCG is presented. Furthermore, we summarize the existing evidence regarding the clinical impact on reproductive outcomes after endometrial priming with HCG prior to embryo transfer. Although promising, further evidence is needed to clarify the protocol that would lead to beneficial outcomes.

hCG Triggering in ART: An Evolutionary Concept

Human chorionic gonadotropin (hCG) is no longer a single, omnipotent ovulation triggering option. Gonadotropin releasing hormone (GnRH) agonist, initially presented as a substitute for hCG, has led to a new era of administering GnRH agonist followed by hCG triggering. According to this new concept, GnRH agonist enables successful ovum maturation, while hCG supports the luteal phase and pregnancy until placental shift.

Human Chorionic Gonadotropin: Unknown about Known

The last two decade discoveries shift the accent from consideration of human chorionic gonadotripin (hCG) as a hormone, that controls progesterone production by corpus luteum cells, to a powerful paracrine regulator which'in the tandem with its hyperglycozilated analog (hCG-H) induces successful implantation and coordinated dialog between blastocyst and uterus tissues. Ability of hCG to interact with TSH receptor and hCG-H with TGF-beta-RII extend significantly the spectrum of processes controlled by these molecules. Differences between intracellular pathways of signal transduction between hCG and LH mediated by the same receptor (LH/hCG-R) impugn unity of their effector mechanisms previously considered as obvious. Paracine properties-of hCG comprise control of fusing of trophoblasts into syncytiotrophoblasts, angiogenesis, immunity regulation and endometrium predisposition to implantation. Angiogenesis is associated with LH/hCG-R expressed on mural cells of uterine spiral arteries as well as induced secretion of soluble VEGF type by endometrial cells. hCG.regulates ratio between different forms of T-helper cells in maternal organism on the initial gestation stage determining high level of Th2 cells. hCG supports local immunotolerance acting as chemoattractant for T-suppressors (T-Treg) and apoptotic factor for T-lymphocytes. Endometrial susceptibility arises from activation of osteopantin secretion and decline of mucin secretion by epithelial cells. hCG-H acts on the same tissues as hCG as a paracrine agent regulating multiple cascades of cytokines. hCG-H plays the key role in trophoblast invasion into,uterine decidua as a result of gelatinase secretion by these cells.The degree of angiogenic effect of hCG-H is compatiblewith hCG but its signal transduction is mediated by TGF-beta signal transduction pathway that stimulates mural cell proliferation. hCG-H acts as mitogen on NK-cells and is able to activate them and direct to angiogenesis maintenance. In this article the attempt was made to elucidate the most important discoveries about the role of hCG and its hyperglycosylated analog yet accomplished and still upcoming.

[The Influence of Chorionic Gonadotropin and Estriol on NK Cells Phenotype and Functional Activity.]

The influence of chorionic gonadotropin (CG) and estriol (E3) at concentrations typical of pregnancy on the expression of phenotypic markers and cytokine production by separated NK cells were studied. It is found that these hormones increase the percentage of CD56brightL-selectin+ NK-cells, but also stimulate the expression of the inhibitory molecule NKG2A in the lymphocytes. In addition, E3 and CG stimulate the production of TGF-B, inhibiting the secretion of all other cytokines by separated NK cells. In general, these hor- mones contribute to the formation of the phenotype and cytokine spectrum characteristic of the regulatory NK3 subpopulation of NK cells during pregnancy.

Testicular germ cell tumour presenting as thyrotoxicosis

A case is reported of a patient who presented to his family doctor with a short history of cough with signs and symptoms of thyrotoxicosis. Carbimazole treatment had little effect and his symptoms worsened to include severe shortness of breath. He was investigated further and found to have multiple lung and liver metastases from an unknown primary site. Biopsy and subsequent post-mortem investigations revealed a testicular tumour and a grossly elevated serum human chorionic gonadotrophin (hCG) concentration.

The biochemical and clinical thyrotoxicosis is presumed to be due to the thyrotrophic activity of excess hCG secretion, in a situation analogous to that seen in hydatidiform mole or in hyperemesis gravidarum.

Review: hCGs: different sources of production, different glycoforms and functions

Human chorionic gonadotropin (hCG) is the first hormonal message from the placenta to the mother. It is detectable in maternal blood two days after implantation and behaves like an agonist of LH stimulating progesterone secretion by the corpus luteum. hCG has also a role in quiescence of the myometrium and local immune tolerance. Specific to humans, hCG is a complex glycoprotein composed of two glycosylated subunits. The α-subunit is identical to the pituitary gonadotropin hormones (LH, FSH, TSH), contains two N-glycosylation sites, and is encoded by a single gene (CGA). By contrast the β-subunits are distinct in each of the hormones and confer receptor and biological specificity. The hCG β-subunit contains two sites of N-glycosylation and four sites of O-glycosylation and is encoded by a cluster of genes (CGB). In this review, we will stress the importance of hCG glycosylation state, which varies with the stage of pregnancy, its source of production and in the pathology. It is well established that hCG is mainly secreted by the syncytiotrophoblast into maternal blood where it peaks around 8-10 weeks of gestation (WG). The invasive extravillous trophoblast also secretes hCG, and in particular like choriocarcinoma cells, hyperglycosylated forms of hCG (hCG-H). In maternal blood hCG-H is high during early first trimester. In addition to its endocrine role, hCG has autocrine and paracrine roles. It promotes formation of the syncytiotrophoblast and angiogenesis through LHCG receptor. In contrast, hCG-H stimulates trophoblast invasion and angiogenesis by interacting with the TGFβ receptor 2. hCG is largely used in antenatal screening and hCG-H represents a serum marker of early trophoblast invasion. Other abnormally glycosylated hCG are described in aneuploidies. In conclusion, hCG is the major pregnancy glycoprotein hormone, whose maternal concentration and glycan structure change all along pregnancy. Depending on its source of production, glycoforms of hCG display different biological activities and functions that are essential for pregnancy outcome.

Non trophoblastic source of human chorionic gonadotropin - problem in diagnostic accuracy

Human chorionic gonadotropin (hCG) is a polypeptide hormone studied as far as 1912, but researchers has no complete knowledge concerning its biological function. Since 1970' it is known that hCG can be found not only in the urine and serum of pregnant, but in choriocarcinoma and testicular cancer patients. Up-to-date one can distinguish four subtypes of hCG differing in secondary carbohydrate chains configuration as well as it regular and glycosylated forms, but non trophoblastic sources of this hormone, such as pituitary are still not widely known. The article gives an overlook on hCG studies in order to help clinicians in taking wise, evidence based decisions in asymptomatic patients with elevated hCG.

The Role of Human Chorionic Gonadotropin as Tumor Marker: Biochemical and Clinical Aspects

Tumor markers are biological substances that are produced/released mainly by malignant tumor cells, enter the circulation in detectable amounts and are potential indicators of the presence of a tumor. The most useful biochemical markers are the tumor-specific molecules, i.e., receptors, enzymes, hormones, growth factors or biological response modifiers that are specifically produced by tumor cells and not, or minimally, by the normal counterpart (Richard et al. Principles and practice of gynecologic oncology. Wolters Kluwer Health, Philadelphia, 2009). Based on their specificity and sensitivity in each malignancy, biomarkers are used for screening, diagnosis, disease monitoring and therapeutic response assessment in clinical management of cancer patients.This chapter is focused on human chorionic gonadotropin (hCG), a hormone with a variety of functions and widely used as a tumor biomarker in selected tumors. Indeed, hCG is expressed by both trophoblastic and non-trophoblastic human malignancies and plays a role in cell transformation, angiogenesis, metastatization, and immune escape, all process central to cancer progression. Of note, hCG testing is crucial for the clinical management of placental trophoblastic malignancies and germ cell tumors of the testis and the ovary. Furthermore, the production of hCG by tumor cells is accompanied by varying degrees of release of the free subunits into the circulation, and this is relevant for the management of cancer patients (Triozzi PL, Stevens VC, Oncol Rep 6(1):7-17, 1999).The name chorionic gonadotropin was conceived: chorion derives from the latin chordate meaning afterbirth, gonadotropin indicates that the hormone is a gonadotropic molecule, acting on the ovaries and promoting steroid production (Cole LA, Int J Endocrinol Metab 9(2):335-352, 2011). The function, the mechanism of action and the interaction between hCG and its receptor continue to be the subject of intensive investigation, even though many issues about hCG have been well documented (Tegoni M et al., J Mol Biol 289(5):1375-1385, 1999).

Steroid-induced oocyte maturation in Indian shad Tenualosa ilisha (Hamilton, 1822) is dependent on phosphatidylinositol 3 kinase but not MAP kinase activation

Fully grown fish and amphibian oocytes exposed to a maturation-inducing steroid (MIS) activates multiple signal transduction pathways, leading to formation and activation of maturation-promoting factor (MPF) and induction of germinal vesicle breakdown (GVBD). The present study was to investigate if phosphatidylinositol 3 kinase (PI3 kinase) and mitogen-activated protein kinase (MAP kinase) activation are required for naturally occurring MIS, 17α,20β-dihydroxy-4-pregnen-3-one (17,20β-P)-induced cdc2 activation and oocyte maturation (OM) in Tenualosa ilisha. We observed that 17,20β-P-induced OM was significantly inhibited by PI3 kinase inhibitors Wortmannin and LY29400. 17,20 β-P was shown to activate PI3 kinase maximally at 90 min and cdc2 kinase at 16 h of treatment. Relative involvement of PI3 kinase, MAP kinase and cdc2 kinase in 17,20β-P-induced OM was examined. MAP kinase was rapidly phosphorylated and activated (60-120 min) after MIS treatment and this response preceded the activation of cdc2 kinase by several hours. A selective inhibitor of MAP kinase (MEK), PD98059, sufficiently blocked the phosphorylation and activation of MAP kinase. Inhibition of MAP kinase activity using PD98059 however, had no effect on MIS-induced cdc2 kinase activation and GVBD. These results demonstrate that activation of the PI3 kinase is required for 17,20β-P-induced cdc2 kinase activation and OM in T. ilisha. MAP kinase although was activated in response to 17,20β-P and PI3 kinase activation, it is not necessary for cdc2 activation and OM in this species.

Elevated hypothalamic aromatization at the onset of precocious puberty in transgenic female mice hypersecreting human chorionic gonadotropin: effect of androgens

Transgenic female mice overexpressing the α- and β- subunits of human chorionic gonadotropin (hCGαβ+) exhibited precocious puberty, as evidenced by early vaginal opening. Chronically elevated hCG in 21-day-old hCGαβ+ females stimulated gonadal androgen production, which exerted negative feedback over the endogenous gonadotropin synthesis, and activated the hypothalamic GnRH pulsatility and gene expression. Transgenic females also exhibited elevated hypothalamic aromatization in the preoptic area (POA), which is the sexually-differentiated area that controls the LH surge in adulthood. Ovariectomy at 14 days of age was unable to rescue this phenotype. However, the blockade of androgen action by flutamide from postnatal day 6 onwards reduced the aromatase levels in the POA of hCGαβ+ females. Our results suggest that early exposure of females to androgen action during a critical period between postnatal days 6-14 induces sex-specific organizational changes of the brain, which affect the aromatase expression in the POA at the onset of precocious puberty.

Luteinizing hormone and human chorionic gonadotropin: distinguishing unique physiologic roles

Luteinizing hormone (LH) and human chorionic gonadotropin (hCG) are integral components of the hypothalamic-pituitary-gonadal axis, which controls sexual maturation and functionality. In the absence of signaling through their shared receptor, fetal sexual differentiation and post-natal development cannot proceed normally. Although they share a high degree of homology, the physiologic roles of these hormones are unique, governed by differences in expression pattern, biopotency and regulation. Whereas LH is a key regulator of gonadal steroidogenesis and ovulation, hCG is predominantly active in pregnancy and fetal development. Emerging evidence has revealed endogenous functions not previously ascribed to hCG, including participation in ovulation and fertilization, implantation, placentation and other activities in support of successful pregnancy. Spontaneous and induced mutations in LH, hCG and their mutual receptor have contributed substantially to our understanding of reproductive development and function. The lack of naturally occurring, functionally significant mutations in the β-subunit of hCG reinforce its putative role in establishment of pregnancy. Rescue of reproductive abnormalities resulting from aberrant gonadotropin signaling is possible in certain clinical contexts, depending on the nature of the underlying defect. By understanding the physiologic roles of LH and hCG in normal and pathologic states, we may better harness their diagnostic, prognostic and therapeutic potential.

Expression and functional activity of PACAP and its receptors on cumulus cells: effects on oocyte maturation

Pituitary adenylate cyclase-activating polypeptide (PACAP) and its receptor PAC1-R (PACAP type 1 receptor) are transiently expressed in granulosa cells (GCs) of mouse preovulatory follicles and affect several parameters associated with the ovulatory process. We investigated the expression of PACAP and its receptors in cumulus cells (CCs) after the LH surge and their role on cumulus expansion/apoptosis and oocyte maturation. PACAP and PAC1-R expression increased in CCs isolated at different times after treatment with human chorionic gonadotropin (hCG). Moreover, PACAP was able to reverse the inhibition of oocyte meiotic maturation caused by hypoxantine in cumulus cell-oocyte complexes (COCs) and efficiently promoted male pronuclear formation after fertilisation. PACAP was also able to induce cumulus expansion and prevent CC apoptosis. Our results demonstrated the induction of PACAP and its receptors in CCs by LH and EGF, suggesting that PACAP may play a significant role in the complex interactions of gonadotropin and growth factors during ovulation and fertilisation.

Human chorionic gonadotropin and its free β-subunit stimulate trophoblast invasion independent of LH/hCG receptor

Both paracrine and autocrine factors are involved in the regulation of trophoblast invasion. One of these factors is human chorionic gonadotropin (hCG), which stimulates trophoblast invasion. The stimulatory activity has especially been ascribed to a hyperglycosylated form of hCG (hCG-h) that is expressed in early pregnancy. We compared the stimulatory activities of different forms of hCG and its free β-subunit (hCGβ) on trophoblast invasion. hCG, hCG-h, hCGβ, and its hyperglycosylated form (hCGβ-h) stimulated the invasion of JEG-3 choriocarcinoma cells. The stimulatory effect of hCGβ was also confirmed with primary human trophoblasts. Down-regulation of the LH/hCG receptor by RNA-interference did not significantly reduce the effect of hCGβ and hCG on cell invasion. Increased invasion was associated with increased levels of MMP-2, MMP-9 and activity of uPA. Our findings suggest that hCG, hCGβ and their hyperglycosylated forms stimulate the invasion of trophoblast cells independent of the classical LH/hCG-receptor.

Human chorionic gonadotropin controls luteal vascular permeability via vascular endothelial growth factor by down-regulation of a cascade of adhesion proteins

OBJECTIVE

To study the functional interactions of junctional proteins acting as regulators of vascular permeability in the human corpus luteum. We investigated the role of vascular endothelial (VE)-cadherin, nectin 2, and claudin 5 as controllers of vascular endothelial cell permeability.

DESIGN

Performing immunohistochemical dual staining, we colocalized the above-mentioned proteins in the human corpus luteum.

SETTING

Not applicable.

PATIENT(S)

Not applicable.

INTERVENTION(S)

Not applicable.

MAIN OUTCOME MEASURE(S)

Using a granulosa-endothelial coculture system, we revealed that hCG-treatment down-regulates VE-cadherin, nectin 2, and claudin 5 in endothelial cells via vascular endothelial growth factor (VEGFA).

RESULT(S)

Furthermore, the interaction of VE-cadherin, nectin 2, and claudin 5 was investigated by silencing these proteins that perform siRNA knockdown. Interestingly, knockdown of VE-cadherin and claudin 5 induced a decrease of the respective other protein. This down-regulation was associated with changed rates of vascular permeability: hCG induced a VEGFA-dependent down-regulation of VE-cadherin, nectin 2, and claudin 5, which increased the endothelial permeability in the coculture system. Furthermore, knockdown of VE-cadherin, nectin-2, and claudin 5 also resulted in a consecutive increase of endothelial permeability for each different protein.

CONCLUSION(S)

These results demonstrate for the first time that VE-cadherin, nectin 2, and claudin 5 are involved in the regulation of vascular permeability in a mutually interacting manner, which indicates their prominent role for the functionality of the human corpus luteum.

The role for runt related transcription factor 2 (RUNX2) as a transcriptional repressor in luteinizing granulosa cells

Transcription factors induced by the LH surge play a vital role in reprogramming the gene expression in periovulatory follicles. The present study investigated the role of RUNX2 transcription factor in regulating the expression of Runx1, Ptgs2, and Tnfaip6 using cultured granulosa cells isolated from PMSG-primed immature rats. hCG or forskolin+PMA induced the transient increase in Runx1, Ptgs2, and Tnfaip6 expression, while the expression of Runx2 continued to increase until 48 h. The knockdown of the agonist-stimulated Runx2 expression increased Runx1, Ptgs2, and Tnfaip6 expression and PGE(2) levels in luteinizing granulosa cells. Conversely, the over-expression of RUNX2 inhibited the expression of these genes and PGE(2) levels. The mutation of RUNX binding motifs in the Runx1 promoter enhanced transcriptional activity of the Runx1 promoter. The knockdown and overexpression of Runx2 increased and decreased Runx1 promoter activity, respectively. ChIP assays revealed the binding of RUNX2 in the Runx1 and Ptgs2 promoters. Together, these novel findings provide support for the role of RUNX2 in down-regulation of Runx1, Ptgs2, and Tnfaip6 during the late ovulatory period to support proper ovulation and/or luteinization.

LH and hCG action on the same receptor results in quantitatively and qualitatively different intracellular signalling

Human luteinizing hormone (hLH) and chorionic gonadotropin (hCG) act on the same receptor (LHCGR) but it is not known whether they elicit the same cellular and molecular response. This study compares for the first time the activation of cell-signalling pathways and gene expression in response to hLH and hCG. Using recombinant hLH and recombinant hCG we evaluated the kinetics of cAMP production in COS-7 and hGL5 cells permanently expressing LHCGR (COS-7/LHCGR, hGL5/LHCGR), as well as cAMP, ERK1/2, AKT activation and progesterone production in primary human granulosa cells (hGLC). The expression of selected target genes was measured in the presence or absence of ERK- or AKT-pathways inhibitors. In COS-7/LHCGR cells, hCG is 5-fold more potent than hLH (cAMP ED₅₀: 107.1±14.3 pM and 530.0±51.2 pM, respectively). hLH maximal effect was significantly faster (10 minutes by hLH; 1 hour by hCG). In hGLC continuous exposure to equipotent doses of gonadotropins up to 36 hours revealed that intracellular cAMP production is oscillating and significantly higher by hCG versus hLH. Conversely, phospho-ERK1/2 and -AKT activation was more potent and sustained by hLH versus hCG. ERK1/2 and AKT inhibition removed the inhibitory effect on NRG1 (neuregulin) expression by hLH but not by hCG; ERK1/2 inhibition significantly increased hLH- but not hCG-stimulated CYP19A1 (aromatase) expression. We conclude that: i) hCG is more potent on cAMP production, while hLH is more potent on ERK and AKT activation; ii) hGLC respond to equipotent, constant hLH or hCG stimulation with a fluctuating cAMP production and progressive progesterone secretion; and iii) the expression of hLH and hCG target genes partly involves the activation of different pathways depending on the ligand. Therefore, the LHCGR is able to differentiate the activity of hLH and hCG.

The alternative Epac/cAMP pathway and the MAPK pathway mediate hCG induction of leptin in placental cells

Pleiotropic effects of leptin have been identified in reproduction and pregnancy, particularly in the placenta, where it works as an autocrine hormone. In this work, we demonstrated that human chorionic gonadotropin (hCG) added to JEG-3 cell line or to placental explants induces endogenous leptin expression. We also found that hCG increased cAMP intracellular levels in BeWo cells in a dose-dependent manner, stimulated cAMP response element (CRE) activity and the cotransfection with an expression plasmid of a dominant negative mutant of CREB caused a significant inhibition of hCG stimulation of leptin promoter activity. These results demonstrate that hCG indeed activates cAMP/PKA pathway, and that this pathway is involved in leptin expression. Nevertheless, we found leptin induction by hCG is dependent on cAMP levels. Treatment with (Bu)₂cAMP in combination with low and non stimulatory hCG concentrations led to an increase in leptin expression, whereas stimulatory concentrations showed the opposite effect. We found that specific PKA inhibition by H89 caused a significant increase of hCG leptin induction, suggesting that probably high cAMP levels might inhibit hCG effect. It was found that hCG enhancement of leptin mRNA expression involved the MAPK pathway. In this work, we demonstrated that hCG leptin induction through the MAPK signaling pathway is inhibited by PKA. We observed that ERK1/2 phosphorylation increased when hCG treatment was combined with H89. In view of these results, the involvement of the alternative cAMP/Epac signaling pathway was studied. We observed that a cAMP analogue that specifically activates Epac (CPT-OMe) stimulated leptin expression by hCG. In addition, the overexpression of Epac and Rap1 proteins increased leptin promoter activity and enhanced hCG. In conclusion, we provide evidence suggesting that hCG induction of leptin gene expression in placenta is mediated not only by activation of the MAPK signaling pathway but also by the alternative cAMP/Epac signaling pathway.

Endocrine, paracrine, and autocrine placental mediators in labor

Considering that preterm birth accounts for about 6-10% of all births in Western countries and of more than 65% of all perinatal deaths, elucidation of the particularly complicated mechanisms of labor is essential for determination of appropriate and effective therapeutic interventions. Labor in humans results from a complex interplay of fetal and maternal factors, which act upon the uterus to trigger pathways leading gradually to a coordinated cervical ripening and myometrial contractility. Although the exact mechanism of labor still remains uncertain, several components have been identified and described in detail. Based on the major role played by the human placenta in pregnancy and the cascade of labor processes activated via placental mediators exerting endocrine, paracrine, and autocrine actions, this review article has aimed at presenting the role of these mediators in term and preterm labor and the molecular pathways of their actions. Some of the aforementioned mediators are involved in myometrial activation and preparation and others in myometrial stimulation leading to delivery. In the early stages of pregnancy, myometrial molecules, like progesterone, nitric oxide, and relaxin, contribute to the retention of pregnancy. At late stages of gestation, fetal hypothalamus maturation signals act on the placenta causing the production of hormones, including CRH, in an endocrine manner; the signals then enhance paracrinically the production of more hormones, such as estrogens and neuropeptides, that contribute to cervical ripening and uterine contractility. These molecules act directly on the myometrium through specific receptors, while cytokines and multiple growth factors are also produced, additionally contributing to labor. In situations leading to preterm labor, as in maternal stress and fetal infection, cytokines trigger placental signaling sooner, thus leading to preterm birth.

Mitochondrial fusion is essential for steroid biosynthesis

Although the contribution of mitochondrial dynamics (a balance in fusion/fission events and changes in mitochondria subcellular distribution) to key biological process has been reported, the contribution of changes in mitochondrial fusion to achieve efficient steroid production has never been explored. The mitochondria are central during steroid synthesis and different enzymes are localized between the mitochondria and the endoplasmic reticulum to produce the final steroid hormone, thus suggesting that mitochondrial fusion might be relevant for this process. In the present study, we showed that the hormonal stimulation triggers mitochondrial fusion into tubular-shaped structures and we demonstrated that mitochondrial fusion does not only correlate-with but also is an essential step of steroid production, being both events depend on PKA activity. We also demonstrated that the hormone-stimulated relocalization of ERK1/2 in the mitochondrion, a critical step during steroidogenesis, depends on mitochondrial fusion. Additionally, we showed that the SHP2 phosphatase, which is required for full steroidogenesis, simultaneously modulates mitochondrial fusion and ERK1/2 localization in the mitochondrion. Strikingly, we found that mitofusin 2 (Mfn2) expression, a central protein for mitochondrial fusion, is upregulated immediately after hormone stimulation. Moreover, Mfn2 knockdown is sufficient to impair steroid biosynthesis. Together, our findings unveil an essential role for mitochondrial fusion during steroidogenesis. These discoveries highlight the importance of organelles’ reorganization in specialized cells, prompting the exploration of the impact that organelle dynamics has on biological processes that include, but are not limited to, steroid synthesis.

[Immunological aspect of pregnancy]

Pregnancy is a temporary semi-allograft that survives for nine months. The importance of this event for the survival of the species justifies several tolerance mechanisms that are put into place at the beginning of pregnancy, some of which occur even at the time of implantation. The presence of multiple tolerance mechanisms and the richness of the means employed underline the central importance of the trophoblast. Understanding these mechanisms, and in particular, their integration into an overall scheme, enables the anomalies encountered in certain pathologies of pregnancy to be placed into context. Understanding these mechanisms and their interruption at the end of pregnancy should improve our understanding of disappointing results from current immunological treatments facilitate the implementation of new prophylactic and therapeutic strategies.

hCG, the wonder of today's science

BACKGROUND

hCG is a wonder. Firstly, because hCG is such an extreme molecule. hCG is the most acidic glycoprotein containing the highest proportion of sugars. Secondly, hCG exists in 5 common forms. Finally, it has so many functions ranging from control of human pregnancy to human cancer. This review examines these molecules in detail.

CONTENT

These 5 molecules, hCG, sulfated hCG, hyperglycosylated hCG, hCG free beta and hyperglycosylated free beta are produced by placental syncytiotrophoblast cells and pituitary gonadotrope cells (group 1), and by placental cytotrophoblast cells and human malignancies (group 2). Group 1 molecules are both hormones that act on the hCG/LH receptor. These molecules are central to human menstrual cycle and human pregnancy. Group 2 molecules are autocrines, that act by antagonizing a TGF beta receptor. These molecules are critical to all advanced malignancies.

CONCLUSIONS

The hCG groups are molecules critical to both the molecules of pregnancy or human life, and to the advancement of cancer, or human death.

Extragonadal actions of chorionic gonadotropin

The primary embryonic signal in primates is chorionic gonadotropin (CG, designated hCG in humans), that is classically associated with corpus luteum rescue and progesterone production. However, research over the past decade has revealed the presence of the hCG receptor in a variety of extragonadal tissues. Additionally, discoveries of the multiple variants of hCG, namely, native hCG, hyperglycosylated hCG (hyp-hCG) and the β- subunit of the hyperglycosylated hCG (hCG-free β) has established a role for extragonadal actions of hCG. For the initiation and maintenance of pregnancy, hCG mediates multiple placental, uterine and fetal functions. Some of these include development of syncytiotrophoblast cells, mitotic growth and differentiation of the endometrium, localized suppression of the maternal immune system, modulation of uterine morphology and gene expression and coordination of intricate signal transduction between the endometrium. Recurrent pregnancy loss, pre-eclampsia and endometriosis are associated with altered responses of hCG, all of which have a detrimental effect on pregnancy. A role for hyp-hCG in mediating the development of both trophoblastic and non-trophoblastic tumors has also been suggested. Other significant non-gonadal applications of hCG include predicting preeclampsia, determining the risk of Down's syndrome and gestational trophoblastic disease, along with relaxing myometrial contractility and preventing recurrent miscarriages. Presence of hCG free-β in serum of cancer patients enables its usage as a diagnostic tumor marker. Thus, the extragonadal functions of hCG encompasses a wide spectrum of applications and is an open area for continued investigation.

Does hCG or hCGβ play a role in cancer cell biology?

The role that hCG might play in the oncogenic process in cancer is certainly complex. We know that the expression of hCG and its beta subunit is a widespread phenomenon which has been described in many cancer subtypes. However, hCG's involvement in breast cancer has been antithetical: the detection of ectopically expressed hCG(β) by breast tumors has been employed as a biomarker of malignancy, and hCG has been proposed as a ligand vehicle for toxic drugs, with the aim of targeting the LH/hCG receptor which is reported to be expressed by malignant breast tissue. However, it has also been proposed that hCG is a protective agent against the development of breast cancer, leading some to advocate hCG administration to non-pregnant women as a prophylactic measure against cancer. Nevertheless, suggestions that hCG is involved in the angiogenesis, metastasis and immune escape that are central to cancer progression - are phenomena which clearly apply to breast cancer. Indeed, a tumor vaccine based upon hCG has very recently been shown to protect against mammary tumors in mice. We propose that this apparent paradox is resolved if the free beta subunit of hCG produced by tumors acts as an autocrine anti-apoptotic and angiogenic growth factor, whilst intact heterodimeric hCG, as in pregnancy, is part of developmental signaling that initiates tissue differentiation (including breast ductal tissue development), and hence reduces the population of stem-like cells which are susceptible to oncogenic factors.

Hyperglycosylated hCG is a marker of early human trophoblast invasion

CONTEXT

Human chorionic gonadotropin (hCG) is the major pregnancy glycoprotein hormone whose maternal concentration and glycan structure change all along pregnancy. hCG is mainly secreted by the syncytiotrophoblast covering the chorionic villi, but little is known about the source of hyperglycosylated hCG (hCG-H) production.

OBJECTIVE

The objective of the study was to analyze expression and secretion of hCG and hCG-H in vitro during human trophoblastic cell differentiation, in situ in first-trimester placentas, and in maternal sera during early pregnancy.

DESIGN

hCG and hCG-H were measured in cell supernatants from primary cultures of first-trimester placenta trophoblastic cells, which differentiate in vitro into syncytiotrophoblast or invasive extravillous cytotrophoblasts (evct). hCG-H immunodetection were performed on 9 wk gestation (WG) placental tissue sections. Total hCG and hCG-H were quantified by chemiluminometric assay in 539 maternal sera collected between 9 and 19 WG during normal pregnancies.

RESULTS

In vitro, hCG secretion reached 37 ng/ml per μg DNA during syncytiotrophoblast formation but contained few hCG-H (2-5% of total hCG). In contrast, hCG secretion (20 ng/ml per μg DNA) in evct supernatants contained 10-20% hCG-H. In situ, hCG-H immunostaining was strong in invasive and endovascular evct, weaker in mononucleated villous cytotrophoblasts, but negative in the syncytiotrophoblast. In maternal sera, hCG-H concentrations continuously decreased during pregnancy from 406 ± 222 ng/ml at 9 WG to 8 ± 6 ng/ml at 19 WG, whereas total hCG picked up at 11 WG and then decreased.

CONCLUSIONS

This study suggests that the high levels of hCG-H observed in first-trimester maternal sera are mainly from invasive evct origin, reflecting the early trophoblast invasion process.

Biological functions of hCG and hCG-related molecules

BACKGROUND

hCG is a term referring to 4 independent molecules, each produced by separate cells and each having completely separate functions. These are hCG produced by villous syncytiotrophoblast cells, hyperglycosylated hCG produced by cytotrophoblast cells, free beta-subunit made by multiple primary non-trophoblastic malignancies, and pituitary hCG made by the gonadotrope cells of the anterior pituitary.

RESULTS AND DISCUSSION

hCG has numerous functions. hCG promotes progesterone production by corpus luteal cells; promotes angiogenesis in uterine vasculature; promoted the fusion of cytotrophoblast cell and differentiation to make syncytiotrophoblast cells; causes the blockage of any immune or macrophage action by mother on foreign invading placental cells; causes uterine growth parallel to fetal growth; suppresses any myometrial contractions during the course of pregnancy; causes growth and differentiation of the umbilical cord; signals the endometrium about forthcoming implantation; acts on receptor in mother's brain causing hyperemesis gravidarum, and seemingly promotes growth of fetal organs during pregnancy. Hyperglycosylated hCG functions to promote growth of cytotrophoblast cells and invasion by these cells, as occurs in implantation of pregnancy, and growth and invasion by choriocarcinoma cells. hCG free beta-subunit is produced by numerous non-trophoblastic malignancies of different primaries. The detection of free beta-subunit in these malignancies is generally considered a sign of poor prognosis. The free beta-subunit blocks apoptosis in cancer cells and promotes the growth and malignancy of the cancer. Pituitary hCG is a sulfated variant of hCG produced at low levels during the menstrual cycle. Pituitary hCG seems to mimic luteinizing hormone actions during the menstrual cycle.

Aberrant G-protein coupled receptor expression in relation to adrenocortical overfunction

The aberrant adrenal expression and function of one or several G-protein coupled receptors can lead to cell proliferation and abnormal regulation of steroidogenesis in unilateral adenomas, carcinomas or in ACTH-independent macronodular adrenal hyperplasia (AIMAH). Excess cortisol secretion leading to either sub-clinical or overt Cushing's syndrome is the most prevalent phenotype reported to date. In a few patients, aberrant regulation of androgen excess has been reported. More recently, initial studies suggest that similar mechanisms are involved in the renin-independent regulation of aldosterone secretion in primary aldosteronism. In recent years, cases of familial AIMAH have been identified, and specific aberrant hormone receptors are functional in the adrenal of affected members. The identification of aberrant receptors can offer specific pharmacological approach to prevent disease progression and control abnormal steroidogenesis; alternatively, unilateral or bilateral adrenalectomy remains the treatment of choice.

Regulation of the angiopoietin-2 gene by hCG in ovarian cancer cell line OVCAR-3

Angiogenesis is a crucial step in growing tissues including many tumors. It is regulated by pro- and antiangiogenic factors including the family of angiopoietins and their corresponding receptors. In previous work we have shown that in human ovarian cells the expression of angiopoietin 2 (ANG2) is regulated by human chorionic gonadotropin (hCG). To better understand the mechanisms of hCG-dependent regulation of the ANG2-gene we have now investigated upstream regulatory active elements of the ANG2-promoter in the ovarian carcinoma cell line OVCAR-3. We cloned several ANG2-promoter-fragments of different lengths into a luciferase reporter-gene-vector and analyzed the corresponding ANG2 expression before and after hCG stimulation. We identified regions of the ANG2-promoter between 1 048 bp and 613 bp upstream of the transcriptional start site where hCG-dependent pathways promote a significant downregulation of gene expression. By sequence analysis of this area we found several potential binding sites for transcription factors that are involved in regulation of ANG2-expression, vascular development and ovarian function. These encompass the forkhead family transcription factors FOXC2 and FOXO1 as well as the CCAAT/enhancer binding protein family (C/EBP). In conclusion, we have demonstrated that the regulation of ANG2-expression in ovarian cancer cells is hCG-dependent and we suggest that forkhead transcription factor and C/EBP-dependent pathways are involved in the regulation of ANG2-expression in ovarian cancer cells.

Role of human chorionic gonadotropin in maintaining 11beta-hydroxysteroid dehydrogenase type 2 expression in human placental syncytiotrophoblasts

Proper glucocorticoid exposure in utero is vital for normal fetal organ maturation, but excess glucocorticoids are detrimental to fetal growth and can even predispose the individuals to the high risk of having certain diseases in adulthood. The fetus is protected from 10 times higher maternal glucocorticoid levels by the placental enzyme 11beta-hydroxysteroid dehydrogenase 2 (11beta-HSD2), which converts biologically active cortisol to inactive cortisone. Thus it is of primary importance to understand how this enzyme is regulated. Activation of cAMP/PKA pathway is known to upregulate 11beta-HSD2 expression in placental syncytiotrophoblasts, however the endogenous hormones utilizing this pathway remain largely unknown. By using cultured human placental syncytiotrophoblasts, we demonstrated that inhibition of protein kinase A with H89 attenuated 11beta-HSD2 expression in the syncytiotrophoblasts, suggesting endogenous factors from the syncytiotrophoblasts using this pathway to maintain 11beta-HSD2 expression in the syncytiotrophoblasts. Neutralization of human chorionic gonadotropin (hCG) secreted by the syncytiotrophoblasts with hCG antibody decreased 11beta-HSD2 promoter activity, mRNA and protein expression as well as intracellular cAMP level, while treatment of the syncytiotrophoblasts with exogenous hCG increased 11beta-HSD2 expression, which was attenuated by H89. Furthermore, we found that cortisol increased both hCG expression and secretion. The up-regulation of 11beta-HSD2 expression by cortisol was significantly attenuated by co-treatment with hCG antibody or H89 in the syncytiotrophoblasts. In conclusion, hCG is an important paracrine or autocrine hormone maintaining 11beta-HSD2 expression and the up-regulation of 11beta-HSD2 expression by cortisol may be mediated in part by hCG in the syncytiotrophoblasts.

Chorionic gonadotropin regulates prostaglandin E synthase via a phosphatidylinositol 3-kinase-extracellular regulatory kinase pathway in a human endometrial epithelial cell line: implications for endometrial responses for embryo implantation

Successful implantation necessitates modulation of the uterine environment by the embryo for a specific period of time during the menstrual cycle. Infusion of chorionic gonadotropin (CG) into the oviducts of baboons to mimic embryo transit induces a myriad of morphological, biochemical, and molecular changes in the endometrium. Endometrial epithelial cells from both baboons and humans when stimulated by CG in vitro, activates a cAMP-independent MAPK pathway leading to prostaglandin E(2) (PGE(2)) synthesis. This study shows that in the human endometrial cell line, HES, CG, acting via its G-protein coupled receptor, phosphorylates protein kinase B, c-Raf, and ERK1/2 in a phosphatidylinositol 3-kinase (PI3K)-dependent manner. Furthermore, ERK1/2 phosphorylation is independent of the signaling paradigms of Galpha(s), Galpha(I), and epidermal growth factor receptor (EGFR) transactivation, typical of gonadal cells, indicating an alternative signaling pattern in the endometrium. After phosphorylation by CG, ERK1/2 translocates to the nucleus in a time-dependent manner. Downstream of ERK1/2, CG activates the nuclear transcription factor, Elk1, also in a PI3K-MAPK-dependent manner. Lastly, we show that in HES cells, this pathway regulates the expression of the microsomal enzyme PGE(2) synthase (mPTGES), a terminal prostanoid synthase responsible for PGE(2) synthesis. CG regulates the mPTGES promoter and also induces mPTGES synthesis in HES cells via the PI3K-ERK1/2 pathway. We suggest that this alternative PI3K-ERK-Elk pathway activated by CG regulates prostaglandin production by the endometrial epithelium and serves as an early trigger to prepare the endometrium for implantation.

Crude urinary human chorionic gonadotropin contains variant forms of HCG with low sialic acid content that exhibit an increased thyrotropic activity in CHO cells expressing the human TSH receptor

Hyperthyroidism occurs in association with pregnancy or trophoblastic tumours. This is due to the secretion of thyroid stimulators by trophoblastic cells, most likely hCG or a variant form of hCG. In the present studies we sought to identify hCG variants with enhanced thyrotropic activity contained in crude hCG extract from pregnancy urine (hCGc). Such studies seem now feasible, because highly sensitive assays employing CHO cells transfected with the recombinant human TSH receptor recently became available. Initially, we found the activity of hCGc to both inhibit the binding of 125I-bTSH to CHO-TSHr cells and to stimulate the cAMP release by the cells to be increased, compared to highly purified hCG (hCGp), which was tested in comparable immunological concentrations. We then processed hCGc on a DEAE-52 anionexchange column to separate materials of interest, termed hCGv, from hCGp. HCGv was further purified by gel chromatography, and found to be enriched in terms of both, its holo-hCG immunoactivity and its TSH binding inhibiting activity, compared to hCGc where it was derived from. It also proved more potent than hCGp to bind to recombinant hTSH receptor and to stimulate adenylate cyclase activity in CHO-TSHr cells. Enzymatic desialylation was able to increase the potency of both hCGv and hCGp, and rendered the two desialylated hCG forms nearly equipotent. Isoelectric focusing and direct measurement of sialic acid contents revealed hCGv to be less sialylated than hCGp.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of phospholipase C induced hydrolysis of phospholipids on membrane-bound and water-soluble LH/hCG receptors in porcine corpora lutea

The role of phospholipids in the function of LH/hCG receptors was studied in two receptor preparations: the membrane fraction of porcine corpora lutea (CL) and the water-soluble receptor in follicular fluid (LFF) which was characterized. Digestion of CL membranes with phospholipase C (PL-C) abolished, in a dose responsive manner, specific binding of [125I]hCG and decreased phospholipid concentrations in the membranes. This loss of LH/hCG receptors was prevented by o-phenanthroline, an inhibitor of PL-C. A similar effect on membrane-bound receptors was observed when lipids were extracted with ethanol-diethylether. On the other hand, treatment of water-soluble receptors with PL-C or delipidation of LFF with Amberlit IRA 400 had no effect on [125I]hCG specific binding. These data suggest that phospholipids play an important role in the accessibility of membrane-bound receptors but are not involved in direct interaction of gonadotropin with binding sites.

Reference intervals in evaluation of maternal thyroid function during the first trimester of pregnancy

BACKGROUND

Insufficient function of the thyroid gland can cause low concentrations of thyroid gland hormones which are necessary for the proper development of the foetus brain, especially during the beginning of pregnancy. We determined the reference interval for TSH in the first trimester of pregnancy and the decision point for anti-TPO antibodies' positivity.

METHODS

We tested 5520 women from the central part of the Czech Republic during the first trimester of pregnancy for serum TSH, anti-TPO and FT4 by chemiluminometric immunoanalysis on an ADVIA Centaur system (Siemens). The reference interval for TSH during the first trimester of pregnancy was determined using the log transformation, and then summarized as the geometrical mean (95% CI); following which, a suitable decision point for anti-TPO positivity was set.

RESULTS

The reference interval for TSH was determined to be 0.06-3.67 mU/l. The suppression of TSH was found in 2.93% of the women; a raised concentration of TSH had been found in 4.48% of the women. For anti-TPO, the cut-off was established at 143 kU/l; 11.2% of the pregnant women were found to be anti-TPO positive.

CONCLUSION

Determination of the reference interval for TSH during early pregnancy is one of the basic requirements when implementing a general examination of the thyroid gland at the beginning of pregnancy. The decision level for positivity of anti-TPO is more than double the manufacturer's reference interval.

Inverse regulation of the interferon-gamma receptor and its signaling in human endometrial stromal cells during decidualization

OBJECTIVE

To investigate whether human endometrial stromal cells (ESCs) express the interferon-gamma-receptor (IFN-gamma R) and whether the process of decidualization or human chorionic gonadotropin (hCG) regulate the IFN-gamma R and its signaling pathway.

DESIGN

In vitro experiment.

SETTING

Research laboratory at a medical university center.

PATIENT(S)

Premenopausal women undergoing hysterectomy for benign reasons.

INTERVENTION(S)

Isolation and incubation of ESCs from hysterectomy specimens with 17beta-estradiol, progesterone, recombinant hCG, and IFN-gamma as well as an IFN-gamma R-blocking antibody.

MAIN OUTCOME MEASURE(S)

We analyzed IFN-gamma R and the phosphorylation of signal transducer and activator of transcription 1 (STAT-1) by flow cytometry. We measured IFN-gamma R and interferon response factor 1 (IRF-1) mRNA using semiquantitative real-time reverse transcriptase polymerase chain reaction (RT-PCR).

RESULT(S)

The IFN-gamma R is up-regulated in human ESCs during decidualization without affecting the phosphorylation of STAT-1. Stimulation of IRF-1 by IFN-gamma is reduced in decidualized ESCs. We found that hCG neither regulates the IFN-gamma R nor its signaling pathway.

CONCLUSION(S)

These results show an inverse regulation of the IFN-gamma R and its signaling response via STAT-1 and IRF-1 in human ESCs during decidualization. The early embryonic signal hCG has no effect on this process. This mechanism may finely modulate the reactivity of ESCs to IFN-gamma-mediated signals from immune cells at the implantation site.

New discoveries on the biology and detection of human chorionic gonadotropin

Human chorionic gonadotropin (hCG) is a glycoprotein hormone comprising 2 subunits, alpha and beta joined non covalently. While similar in structure to luteinizing hormone (LH), hCG exists in multiple hormonal and non-endocrine agents, rather than as a single molecule like LH and the other glycoprotein hormones. These are regular hCG, hyperglycosylated hCG and the free beta-subunit of hyperglycosylated hCG. For 88 years regular hCG has been known as a promoter of corpus luteal progesterone production, even though this function only explains 3 weeks of a full gestations production of regular hCG. Research in recent years has explained the full gestational production by demonstration of critical functions in trophoblast differentiation and in fetal nutrition through myometrial spiral artery angiogenesis. While regular hCG is made by fused villous syncytiotrophoblast cells, extravillous invasive cytotrophoblast cells make the variant hyperglycosylated hCG. This variant is an autocrine factor, acting on extravillous invasive cytotrophoblast cells to initiate and control invasion as occurs at implantation of pregnancy and the establishment of hemochorial placentation, and malignancy as occurs in invasive hydatidiform mole and choriocarcinoma. Hyperglycosylated hCG inhibits apoptosis in extravillous invasive cytotrophoblast cells promoting cell invasion, growth and malignancy. Other non-trophoblastic malignancies retro-differentiate and produce a hyperglycosylated free beta-subunit of hCG (hCG free beta). This has been shown to be an autocrine factor antagonizing apoptosis furthering cancer cell growth and malignancy. New applications have been demonstrated for total hCG measurements and detection of the 3 hCG variants in pregnancy detection, monitoring pregnancy outcome, determining risk for Down syndrome fetus, predicting preeclampsia, detecting pituitary hCG, detecting and managing gestational trophoblastic diseases, diagnosing quiescent gestational trophoblastic disease, diagnosing placental site trophoblastic tumor, managing testicular germ cell malignancies, and monitoring other human malignancies. There are very few molecules with such wide and varying functions as regular hCG and its variants, and very few tests with such a wide spectrum of clinical applications as total hCG.

Luteal-phase endocrinology

The corpus luteum is formed from the pre-ovulatory follicle under the action of the mid-cycle LH surge. LH is the main luteotrophic hormone in women controlling luteal structure and function during the normal menstrual cycle. Local factors, however, including progesterone are also involved. If conception does not take place, luteolysis occurs as a physiological apoptotic process. Human chorionic gonadotrophin, secreted after implantation, is able to rescue the corpus luteum and extend its lifespan. In ovulation-induction cycles, the negative feedback effect of the ovarian steroids on the pituitary is markedly potentiated, leading to the suppression of endogenous LH secretion during the whole menstrual cycle. The marked suppression of LH secretion disrupts corpus luteum function regardless of the treatment regimen.

New insights into the evolution of chorionic gonadotrophin

The glycoprotein hormones luteinizing hormone (LH) and chorionic gonadotrophin (CG) are crucial for reproduction, as LH induces sex hormone production and ovulation, and CG is essential for the establishment of pregnancy and fetal male sexual differentiation. Both consist of two heterodimeric peptides of which the alpha-subunit is common to both hormones whereas the beta-subunit is hormone-specific. The CGB gene was derived from LHB by gene duplication and frame shift mutation that led to a read-through into the formerly 3'-untranslated region, giving rise to the carboxyl-terminal peptide. Owing to nucleotide changes within the 5'-region of CGB, a new transcriptional start site and regulatory region was gained. These changes led to the specific expression of CGB in the placenta and its decrease in the pituitary. Recent findings on gonadotrophins led to an extended model for the sequence of events in the evolution of the CGB gene in primates and its tissue-specific expression.

Variability in thyroid-stimulating hormone suppression by human chorionic [corrected] gonadotropin during early pregnancy

OBJECTIVE

The objective of the study was to further explore relationships between human chorionic gonadotropin (hCG), TSH, and free T4 in pregnant women at 11 through 18 wk gestation.

STUDY DESIGN

The design of the study was to analyze hCG in comparison with TSH and free T4, in paired first- and second-trimester sera from 9562 women in the First and Second Trimester Evaluation of Risk for Fetal Aneuploidy trial study.

RESULTS

hCG is strongly correlated with body mass index, smoking, and gravidity. Correlations with selected maternal covariates also exist for TSH and free T4. As hCG deciles increase, body mass index and percent of women who smoke both decrease, whereas the percent of primigravid women increases (P < 0.0001). hCG/TSH correlations are weak in both trimesters (r2 = 0.03 and r2 = 0.02). TSH concentrations at the 25th and fifth centiles become sharply lower at higher hCG levels, whereas 50th centile and above TSH concentrations are only slightly lower. hCG/free T4 correlations are weak in both trimesters (r2 = 0.06 and r2 = 0.003). At 11-13 wk gestation, free T4 concentrations rise uniformly at all centiles, as hCG increases (test for trend, P < 0.0001), but not at 15-18 wk gestation. Multivariate analyses with TSH and free T4 as dependent variables and selected maternal covariates and hCG as independent variables do not alter these observations.

CONCLUSIONS

In early pregnancy, a woman's centile TSH level appears to determine susceptibility to the TSH being suppressed at any given hCG level, suggesting that hCG itself may be the primary analyte responsible for stimulating the thyroid gland. hCG affects lower centile TSH values disproportionately.

Evolution of the human brain, chorionic gonadotropin and hemochorial implantation of the placenta: insights into origins of pregnancy failures, preeclampsia and choriocarcinoma

Hyperglycosylated chorionic gonadotropin (CG-H) signals placental cytotrophoblast cell growth and invasion, and chorionic gonadotropin (CG) promotes uterine vascularization. A hypothesis is presented relating the evolution of these molecules to the evolution of human hemochorial implantation and that of the human brain. Deep placental invasion, vascularization and hemochorial placentation, under the influence of CG and CG-H, are a critical part of the nutrition and energy-generating mechanisms needed for human brain development and thus for the evolution of humans. Insufficient CG-H production and the resulting inappropriate implantation is associated with an unduly high incidence of pregnancy failures in humans. Low levels of CG-H and inappropriate hemochorial placentation also appear to be associated with subsequent preeclampsia. It is also of note that human CG-H drives invasion by gestational trophoblastic neoplasms that have been described only in humans.

Structure and structure-function relationships in glycoprotein hormones

Relationships between the sequences of thyrotropin (thyroid-stimulating hormone, TSH), lutropin (luteinizing hormone, LH), human choriogonadotropin (chorionic gonadotropin, hCG) and follitropin (follicle-stimulating hormone, FSH) are now well established. Each beta-subunit contains six disulphide bonds and considerable homology is seen when all four linear sequences are aligned with half-cystine residues in juxtaposition. Major questions about the tertiary structures of the subunits and their interactions to form active hormone remain. Determination of the disulphide bridges in both alpha- and beta-subunits has not yielded to usual methods and conflicting data about the alpha-subunit have been reported. Partial reduction of the beta-subunits of LH and TSH with subsequent labelling of the cysteines formed has shown that a single bond is first reduced. This bond is between positions 93 and 100 in LH-beta and the corresponding positions 88-95 in TSH-beta. Thus, as would be expected from the fact that interhormone hybrids can be made with the common alpha-subunits, the chemical data, though still limited, indicate similar tertiary structures for the different beta-subunits. To investigate whether other useful intermediates can be obtained after partial reduction, we have studied reduction and derivative formation in various conditions. Intact LH is more resistant to reduction than either its alpha- or beta-subunit but no intermediates have been observed which are not present after partial reduction of individual subunits. Preliminary experiments on the reoxidation of fully reduced alpha-subunit show that the reoxidized material will recombine with native beta-subunits to yield biologically active TSH or LH. Studies from this and other laboratories on chemical modifications of several amino acid residues of glycoprotein hormones and their subunits are also summarized.

Human chorionic gonadotropin and maternal recognition of pregnancy

The corpus luteum of the ovulatory cycle is essential for establishing and maintaining the first seven weeks of human pregnancy. Progesterone, given parenterally, appears to be a satisfactory substitute for the corpus luteum, known to be the source of this steroid hormone during this period. Moreover, hCG appears to be essential for sustained secretion of progesterone by the corpus luteum, particularly during the first three weeks after fertilization. In primates at least, neutralization of the biological effects of CG during this critical period results in a reduction of blood progesterone levels and the interruption of pregnancy. Although alternative sources of hCG exist, and the physiological relevance of these sources requires further study, hCG appears to be essential component in the maternal recognition of pregnancy.

Regulation of hormone production in the human feto-placental unit

Hormone production in the human feto-placental unit has been studied extensively yet relatively little is known about the regulatory mechanisms involved. A tissue culture approach has been used to examine the effect of potential controlling factors on steroid production by the human mid-term fetal adrenal and mid-term and term placenta. Adrenal. The pituitary peptides corticotropin (ACTH) and alpha-melanocyte-stimulating hormone (alpha-MSH) had the most significant influence on adrenal steroidogenesis in both the fetal and definitive zones. Their effects were not identical: they enhanced dehydroepiandrosterone sulphate (DHA-S) production in a comparable manner but alpha-MSH had much less of a stimulatory effect on cortisol biosynthesis. Medium from homologous fetal pituitary cultures mimicked the effects of alpha-MSH rather than ACTH. Homologous placental culture medium and progesterone enhanced only cortisol production and only in the fetal zone cells. These results demonstrate that specific fetal pituitary and placental factors influence fetal adrenal activity and suggest a functional zonation of the fetal adrenal. Placenta. DHA, DHA-S and 16-hydroxy-DHA stimulated oestrogen biosynthesis while high concentrations of DHA and DHA-S (but not 16-hydroxy-DHA) inhibited progesterone production. Luteinizing hormone-releasing hormone (LRH) inhibited both oestrogen and progesterone biosynthesis. Placental steroidogenesis can therefore be influenced not only by the fetus, through its increasing adrenal output of oestrogen precursors, but also by factors originating within the placenta itself.

Human chorionic gonadotropin stimulates trophoblast invasion through extracellularly regulated kinase and AKT signaling

Chorionic gonadotropin (CG) is indispensable for human pregnancy because it controls implantation, decidualization, and placental development. However, its particular role in the differentiation process of invasive trophoblasts has not been fully unraveled. Here we demonstrate that the hormone promotes trophoblast invasion and migration in different trophoblast model systems. RT-PCR and Western blot analyses revealed expression of the LH/CG receptor in trophoblast cell lines and different trophoblast primary cultures. In vitro, CG increased migration and invasion of trophoblastic SGHPL-5 cells through uncoated and Matrigel-coated transwells, respectively. The hormone also increased migration of first-trimester villous explant cultures on collagen I. Proliferation of the trophoblast cell line and villous explant cultures measured by cumulative cell numbers and in situ 5-bromo-2'-deoxyuridine labeling, respectively, was unaffected by CG. Addition of the hormone activated ERK-1/2 and AKT in SGHPL-5 cells and pure, extravillous trophoblasts. Inhibition of MAPK kinase/ERK and phosphatidylinositide 3-kinase/AKT blocked phosphorylation of the kinases and attenuated CG-dependent invasion of SGHPL-5 cells. Similarly, the inhibitors decreased hormone-stimulated migration in villous explant cultures. Western blot analyses and gelatin zymography suggested that CG increased matrix metalloproteinase (MMP)-2 protein levels and activity in both culture systems. Inhibition of ERK or AKT diminished CG-induced MMP-2 expression. In summary, the data demonstrate that CG promotes trophoblast invasion and migration through activation of ERK and AKT signaling involving their downstream effector MMP-2. Because the increase of CG during the first trimester of pregnancy correlates with rising trophoblast motility, the hormone could be a critical regulator of the early invasion process.

Estrogen-2/4-hydroxylase activity is stimulated during germinal vesicle breakdown induced by hCG, IGF-1, GH and insulin in the catfish Heteropneustes fossilis

Estrogen-2/4-hydroxylase (EH) activity was measured radiometrically in ovaries of catfish injected with hCG intraperitoneally and in postvitellogenic follicles incubated with different concentrations of hCG, catfish (Clarias batrachus) growth hormone (GH), bovine insulin or recombinant human insulin-like growth factor-I (rhIGF-I). The change in enzyme activity was correlated with germinal vesicle breakdown (GVBD), an index of oocyte maturation. A single intraperitoneal injection of hCG (100 IU/fish) stimulated EH activity both at 8 and 16 h prior to stripping of eggs. The activity decreased significantly at 24 h, following ovulation. The follicles incubated with hCG, rhIGF-I, insulin or GH elicited biphasic effects on EH activity. rhIGF-I, insulin and GH increased enzyme activity at the lower or median concentrations. hCG and rhIGF-I stimulated EH activity higher than GH or insulin. All the hormones elicited a dose-dependent increase in GVBD, the effect was greater with rhIGF-I (100 nM) and hCG (5.0 IU/ml). The significance of changes in EH activity (E2 hydroxylation) and GVBD were discussed.