Expression of adrenomedullin 2 (ADM2)/intermedin (IMD) in human placenta: role in trophoblast invasion and migration

Insight into the post-translational modifications in pregnancy and related complications†

Successful pregnancy is dependent on a number of essential events, including embryo implantation, decidualization, and placentation. Failure of the above process may lead to pregnancy-related complications, including preeclampsia, gestational diabetes mellitus, preterm birth, and fetal growth restriction, may affect 15% of pregnancies, and lead to increased mortality and morbidity of pregnant women and perinatal infants, as well as the occurrence of short-term and long-term diseases. These complications have distinct etiology and pathogenesis, and the present comprehension is still lacking. Post-translational modifications are important events in epigenetics, altering the properties of proteins through protein hydrolysis or the addition of modification groups to one or more amino acids, with different modification states regulating subcellular localization, protein degradation, protein-protein interaction, signal transduction, and gene transcription. In this review, we focus on the impact of various post-translational modifications on the progress of embryo and placenta development and pregnancy-related complications, which will provide important experimental bases for exploring new insights into the physiology of pregnancy and pathogenesis associated with pregnancy complications.

Role of adrenomedullin2/ intermedin in pregnancy induced vascular and metabolic adaptation in mice

Introduction: Adrenomedullin2 (AM2) shares its receptor with Calcitonin gene related peptide and adrenomedullin with overlapping but distinct biological functions. Goal of this study was to assess the specific role of Adrenomedullin2 (AM2) in pregnancy induced vascular and metabolic adaptation using AM2 knockout mice (AM2 -/-). Method : The AM2 -/- mice were successfully generated using Clustered Regularly Interspaced Short Palindromic Repeats (CRISPR)/Nuclease Cas nine system. Phenotype of pregnant AM2 -/- mice was assessed with respect to its fertility, blood pressure regulation, vascular health and metabolic adaptations and compared to the wild type littermates (AM2 +/+). Results : Current data shows that AM2 -/- females are fertile with no significant difference in number of pups/litter compared to the AM2 +/+. However, ablation of AM2 decreases the gestational length and the total number of pups born dead or that die after birth is greater in AM2 -/- mice compared to AM2 +/+ mice (p < 0.05). Further AM2 -/- mice exhibit elevated blood pressure and elevated vascular sensitivity for the contractile responses to angiotensin two and higher serum sFLT-1 trigylcerides levels compared to AM2 +/+(p < 0.05). In addition, AM2 -/- mice develop glucose intolerance with elevated serum levels of Insulin during pregnancy compared to the AM2 +/+mice. Discussion: Current data suggests a physiological role for AM2 in pregnancy induced vascular and metabolic adaptations in mice.

Embryonic growth retardation and altered expression of IGF-II is reciprocal induced by phytocompounds during early gestation in mice

Methanolic crude extract of Scoparia dulcis (CESD) was orally administered to female mice during the early gestation (day 4-day 8) at a dose of 500 mg/kg/day. It induces embryo resorption and morphological changes of fetal maternal tissue. Histomorphology was studied by routine hematoxylin eosin stain. In situ immunofluorescence localization of IGF-II using Texas red showed an ordered expression of the growth factor in the maternal decidual cells, trophoblast cells and the embryo. Western blot analysis showed a gradual increase of IGF-II from D4 to D8 of control females. In contrast, the CESD-treated females showed resorption of embryo on D8 with disorganized in situ expression and lowered IGF-II in fetal maternal tissue. The phytocompounds present in the CESD could modulate either the ER or IGF-II receptors causing reduced IGF-II expression in the target tissues which lead to the failure of embryonic growth during periimplantation.

A narrative review of the calcitonin peptide family and associated receptors as migraine targets: Calcitonin gene-related peptide and beyond

OBJECTIVE

To summarize the pharmacology of the calcitonin peptide family of receptors and explore their relationship to migraine and current migraine therapies.

BACKGROUND

Therapeutics that dampen calcitonin gene-related peptide (CGRP) signaling are now in clinical use to prevent or treat migraine. However, CGRP belongs to a broader peptide family, including the peptides amylin and adrenomedullin. Receptors for this family are complex, displaying overlapping pharmacologic profiles. Despite the focus on CGRP and the CGRP receptor in migraine research, recent evidence implicates related peptides and receptors in migraine.

METHODS

This narrative review summarizes literature encompassing the current pharmacologic understanding of the calcitonin peptide family, and the evidence that links specific members of this family to migraine and migraine-like behaviors.

RESULTS

Recent work links amylin and adrenomedullin to migraine-like behavior in rodent models and migraine-like attacks in individuals with migraine. We collate novel information that suggests females may be more sensitive to amylin and CGRP in the context of migraine-like behaviors. We report that drugs designed to antagonize the canonical CGRP receptor also antagonize a second CGRP-responsive receptor and speculate as to whether this influences therapeutic efficacy. We also discuss the specificity of current drugs with regards to CGRP isoforms and how this may influence therapeutic profiles. Lastly, we emphasize that receptors related to, but distinct from, the canonical CGRP receptor may represent underappreciated and novel drug targets.

CONCLUSION

Multiple peptides within the calcitonin family have been linked to migraine. The current focus on CGRP and its canonical receptor may be obscuring pathways to further therapeutics. Drug discovery schemes that take a wider view of the receptor family may lead to the development of new anti-migraine drugs with favorable clinical profiles. We also propose that understanding these related peptides and receptors may improve our interpretation regarding the mechanism of action of current drugs.

Calcitonin Gene Related Peptide, Adrenomedullin, and Adrenomedullin 2 Function in Uterine Artery During Human Pregnancy

RATIONALE

Calcitonin gene-related peptide (CGRP) and its family members adrenomedullin (ADM) and adrenomedullin 2 (ADM2; also known as intermedin) support vascular adaptions in rat pregnancy.

OBJECTIVE

This study aimed to assess the relaxation response of uterine artery (UA) for CGRP, ADM, and ADM2 in nonpregnant and pregnant women and identify the involved mechanisms.

FINDINGS

(1) Segments of UA from nonpregnant women that were precontracted with U46619 (1μM) in vitro are insensitive to the hypotensive effects of CGRP, ADM, and ADM2; (2) CGRP, ADM, and ADM2 (0.1-100nM) dose dependently relax UA segments from pregnant women with efficacy for CGRP > ADM = ADM2; (3) the relaxation responses to CGRP, ADM, and ADM2 are differentially affected by the inhibitors of nitric oxide (NO) synthase (L-NAME), adenylyl cyclase (SQ22536), apamin, and charybdotoxin; (4) UA smooth muscle cells (UASMC) express mRNA for calcitonin receptor-like receptor (CRLR) and receptor activity modifying protein (RAMP)1 and RAMP2 but not RAMP3; (5) receptor heterodimer comprising CRLR/RAMP1 and CRLR/RAMP2 but not CRLR/RAMP3 is present in UA; (6) soluble fms-like tyrosine kinase (sFLT-1) and TNF-α treatment decrease the expression of RAMP1 mRNA (P < 0.05) in UASMC; and (7) sFLT-1 treatment impairs the association of CRLR with all 3 peptides while TNF-α inhibits the interaction of CGRP but not ADM or ADM2 with CRLR in UASMC (P < 0.05).

CONCLUSIONS

Relaxation sensitivity of UA for CGRP, ADM, and ADM2 is increased during pregnancy via peptide-specific involvement of NO system and endothelium-derived hyperpolarizing factors; vascular disruptors such as sFLT-1 and TNFα adversely impact their receptor system in UASMC.

Adrenomedullin 2 and 5 activate the calcitonin receptor-like receptor (clr) - Receptor activity-modifying protein 3 (ramp3) receptor complex in Xenopus tropicalis

The adrenomedullin (AM) family is involved in diverse biological functions, including cardiovascular regulation and body fluid homeostasis, in multiple vertebrate lineages. The AM family consists of AM1, AM2, and AM5 in tetrapods, and the receptor for mammalian AMs has been identified as the complex of calcitonin receptor-like receptor (CLR) and receptor activity-modifying protein 2 (RAMP2) or RAMP3. However, the receptors for AM in amphibians have not been identified. In this study, we identified the cDNAs encoding calcrl (clr), ramp2, and ramp3 receptor components from the western clawed frog (Xenopus tropicalis). Messenger RNAs of amphibian clr and ramp2 were highly expressed in the heart, whereas that of ramp3 was highly expressed in the whole blood. In HEK293T cells expressing clr-ramp2, cAMP response element luciferase (CRE-Luc) reporter activity was activated by am1. In HEK293T cells expressing clr-ramp3, CRE-Luc reporter activity was increased by the treatment with am2 at the lowest dose, but with am5 and am1 at higher dose. Our results provided new insights into the roles of AM family peptides through CLR-RAMP receptor complexes in the tetrapods.

Altered expression of ADM and ADM2 by hypoxia regulates migration of trophoblast and HLA-G expression†

Preeclampsia (PE) is a placental disorder caused by endothelial dysfunction via trophoblast inadequate invasion activity. Adrenomedullin (ADM) and ADM2 are multifunctional peptides that can support vascular activity and placental growth. However, correlation between ADMs and trophoblast functions is currently unclear. The objective of this study was to analyze changes in expression of ADMs in placenta and HTR-8/SVneo trophoblast cells under hypoxia and their effects on invasion activity of trophoblast cells and expression of HLA-G. In placental tissues of PE, expression levels of ADM and HLA-G were significantly increased (P < 0.05) whereas expression of ADM2 was decreased compared to that in normal term placenta. Under hypoxia, expression levels of ADM, ADM2, and HLA-G and invasion ability of trophoblast cells were increased in hypoxia-inducible factor-1 (HIF-1α)- dependent manner (P < 0.05). Treatment with ADMs agonists reduced HIF-1α activity whereas enhanced invasion ability under hypoxia. However, they were not changed after cotreatment of ADMs and HIF-1α inhibitor, YC-1, although expression levels of invasion-related genes MMP2, MMP9, and Rac1 were altered (P < 0.05). ADMs also increased HLA-G expression under normoxia whereasADM2 or cotreatment of ADMs under hypoxia attenuated HLA-G expression (P < 0.05). Our findings demonstrate that altered expression of ADMs plays a critical role in placental physiology, especially in trophoblast invasion and immune-modulation under hypoxia.

Adrenomedullin 2/intermedin: a putative drug candidate for treatment of cardiometabolic diseases

Adrenomedullin (ADM) 2/intermedin (IMD) is a short peptide that belongs to the CGRP superfamily. Although it shares receptors with CGRP, ADM and amylin, ADM2 has significant and unique functions in the cardiovascular system. In the past decade, the cardiovascular effect of ADM2 has been carefully analysed. In this review, progress in understanding the effects of ADM2 on the cardiovascular system and its protective role in cardiometabolic diseases are summarized.

LINKED ARTICLES

This article is part of a themed section on Spotlight on Small Molecules in Cardiovascular Diseases. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v175.8/issuetoc.

Adrenomedullin2 (ADM2)/Intermedin (IMD): A Potential Role in the Pathophysiology of Preeclampsia

CONTEXT

It is not known whether decreases in trophoblast invasion promoting the peptide, adrenomedullin2 (ADM2) system is associated with preeclampsia (PreE).

OBJECTIVE

The objective of the study was to assess the changes in ADM2 levels in plasma, placenta, and amniotic fluid (AF) and its receptor components in placenta from PreE pregnancy compared with the age-matched normal and study the effect of ADM2 on the synthesis of nitric oxide (NO), endothelial nitric oxide synthase (eNOS), and matrix-metalloproteinase (MMP)-2 and MMP-9 in trophoblast cells.

RESULTS

PreE is associated with a decreased expression of ADM2 in plasma and placenta (P < .05); ADM2 interacts with a seven-transmembrane G protein-coupled receptor, calcitonin receptor-like receptor (CRLR) in HTR-8/SVneo cells; placental expression of ADM2/CRLR complex is lower in PreE; mRNA for CRLR and receptor activity-modifying protein-3 are lower, whereas receptor activity-modifying protein-2 is higher in the PreE placenta (P < .05); ADM2 levels in the second trimester are lower in the AF from pregnant women who develop PreE later in gestation (P < .05); ADM2 is localized to the epithelium of the amnion and the ectoderm and mesoderm of the chorion in term fetal membranes; ADM2 increases NO production, eNOS, and MMP2/9-immunoreactivity, whereas ADM2 knockdown inhibits the expression of eNOS and MMP2/9 mRNA and S-nitrosylation in HTR-8/SVneo cells; and ADM2-induced increases in MMP2/9 activity is inhibited by L-nitro-arginine methyl ester in HTR-8SV/neo cells.

CONCLUSION

Decreases in the ADM2 system in PreE at term, in AF from pregnant women during the second trimester who develop PreE later in gestation, and ADM2-induced increases in the NO and MMP-2/9 levels in trophoblast cells suggest a potential role for ADM2 via the NO-MMP system in the pathophysiology of PreE.

Impaired Vasodilatory Responses of Omental Arteries to CGRP Family Peptides in Pregnancies Complicated by Fetal Growth Restriction

RATIONALE

Calcitonin gene-related peptide (CGRP), adrenomedullin (ADM), and adrenomedullin2 (ADM2)/intermedin are potent vasorelaxant peptides considered to play a role in the adaptive mechanisms in rat pregnancy through increased vasodilation in mesenteric and uterine artery.

OBJECTIVE

This study was designed to demonstrate the response of omental arteries (OA) to vasoactive peptides CGRP, ADM, and ADM2 in pregnancy complications such as fetal growth restriction (FGR), and assess the changes in the expression of their receptor components in segments of OA from FGR pregnancy compared to the control.

FINDINGS

The findings for this study are: 1) relaxation responses of OA were higher for bradykinin (78.55 ± 3.91 vs 52.67 ± 2.19; P < .05) in pregnancy with FGR compared to the normal, 2) relaxation response of OA segments to CGRP was similar with no change in the expression of G-protein couple receptor-calcitonin receptor-like receptor complex in normal healthy pregnancy and pregnancy complicated by FGR, 3) maximal relaxation response of OA were significantly (P < .05) lower for both ADM (18.2 ± 6.7 vs 38 ± 2.5) and ADM2 (26.9 ± 6.7 vs 48 ± 2.6) along with decreases in their respective ligand-receptor complex in FGR compared to the normal pregnancies, 4) expression of calcitonin receptor-like receptor mRNA was higher but its immunoreactivity was lower in OA from FGR pregnancy compared to the normal, and 5) mRNA and protein levels of RAMP1, RAMP2, and RAMP3 were lower in OA isolated from FGR pregnancies compared to the normal.

CONCLUSION

The current study demonstrates that FGR is associated with an increase in the sensitivity of OA to bradykinin and decreased sensitivity for ADM and ADM2 ligand-receptor system with no change in the response for CGRP compared to the normal healthy pregnancy, and suggests a potential role for ADM and ADM2 in the pathophysiology of maternal vasculature in FGR pregnancy.

Intermedin/adrenomedullin 2 polypeptide promotes adipose tissue browning and reduces high-fat diet-induced obesity and insulin resistance in mice

OBJECTIVES

There is an urgent need to develop interventions and policies to mitigate the health effects of obesity by targeting its metabolic mediators. Adrenomedullin 2 (AM2)/intermedin (IMD) is a secreted peptide that has an important role in protecting the cardiovascular system. However, the role of AM2 in type 2 diabetes is unknown.

METHODS

Wild-type (WT) and aP2/AM2 transgenic (aAM2-tg) mice were fed a high-fat diet (HFD) for 8 weeks, and WT mice were treated with AM2 through mini-osmotic pumps. Indirect calorimetry, ambulatory activity and food intake, hyperinsulinemic-euglycemic clamp test, glucose and insulin tolerance tests were used for assessing insulin resistance. Rat primary adipocytes and pre-adipocyte-derived adipocytes were used for in vitro experiments. Real-time PCR and western blot were used for analyses of gene expression and protein level.

RESULTS

AM2 and receptor activity-modifying proteins expressions were significantly decreased in the adipose tissue of obese mice. AM2 treatment significantly reduced blood glucose, fasting serum insulin and free fatty acid levels, improved glucose tolerance and insulin sensitivity, and increased the glucose infusion rate during a hyperinsulinemic-euglycemic clamp test, indicating ameliorated HFD-induced insulin resistance. These effects were consistently observed in aAM2-tg mice under HFD conditions, whereas the aAM2-tg mice showed less weight gain and improved glucose tolerance and insulin sensitivity. More importantly, the aAM2-tg mice had increased oxygen consumption and CO2 production, reflecting more energy expenditure. These effects may be due to increased AMP-activated protein kinase phosphorylation and reduced peroxisome proliferator-activated receptor gamma co-activator 1α (PGC1α) acetylation, which result in interactions between PGC1α and PR domain containing 16 and then promote uncoupling protein 1 (UCP1) expression in adipocytes.

CONCLUSIONS

These results indicate that endogenous AM2 might be involved in energy metabolism in adipocytes through the upregulation of UCP1 expression.

Adrenomedullin 2 (ADM2) Regulates Mucin 1 at the Maternal-Fetal Interface in Human Pregnancy

Association of an altered expression of placental mucin 1 (MUC1) with first-trimester spontaneous abortion and its regulation in placenta by an invasion-promoting peptide, adrenomedullin 2 (ADM2), is not known. The objective of this study was to assess 1) the association of MUC1 mRNA expression in the placental villi and decidua with first-trimester spontaneous abortion, 2) the effects of ADM2 on the expression of MUC1 in trophoblast cells in the presence or absence of hypoxia, 3) the effects of ADM2 on expression of MUC1 in decidual stromal cells (DSCs), and 4) if ADM2 regulates the expression of MUC1 and MMP2 protein in trophoblastic spheroids. Data demonstrate that 1) expression of MUC1 mRNA in villous tissue is higher in spontaneous abortion compared to age-matched electively terminated pregnancies (P > 0.05), 2) ADM2 decreases the expression of MUC1 mRNA and protein in trophoblast cells and spheroids with concomitant increases in MMP2 immunoreactivity in the spheroids, 3) ADM2 decreases hypoxia-induced increases in MUC1 immunoreactivity in trophoblast cells, 4) decidual MUC1 mRNA expression is lower in spontaneous compared to elective abortions (P < 0.05), and 5) DSCs express MUC1 mRNA and protein and ADM2 decreases the expression of MUC1 mRNA and protein in DSCs. Taken together, this study demonstrates that first-trimester spontaneous abortion is associated with increases in MUC1 expression in villi and decreases in the decidual tissues, and suggests that ADM2 may contribute to the physiology of embryo implantation and placental growth via increasing MMP2 and decreasing MUC1 expression to facilitate trophoblast invasion.

Placenta: the forgotten organ

The placenta sits at the interface between the maternal and fetal vascular beds where it mediates nutrient and waste exchange to enable in utero existence. Placental cells (trophoblasts) accomplish this via invading and remodeling the uterine vasculature. Amazingly, despite being of fetal origin, trophoblasts do not trigger a significant maternal immune response. Additionally, they maintain a highly reliable hemostasis in this extremely vascular interface. Decades of research into how the placenta differentiates itself from embryonic tissues to accomplish these and other feats have revealed a previously unappreciated level of complexity with respect to the placenta's cellular composition. Additionally, novel insights with respect to roles played by the placenta in guiding fetal development and metabolism have sparked a renewed interest in understanding the interrelationship between fetal and placental well-being. Here, we present an overview of emerging research in placental biology that highlights these themes and the importance of the placenta to fetal and adult health.

Involvement of Receptor Activity-Modifying Protein 3 (RAMP3) in the Vascular Actions of Adrenomedullin in Rat Mesenteric Artery Smooth Muscle Cells

CALCB, ADM, and ADM2 are potent vasodilators that share a seven-transmembrane GPCR, calcitonin receptor-like receptor (CALCRL), whose ligand specificity is dictated by the presence of one of the three receptor activity-modifying proteins (RAMPs). We assessed the relative pharmacologic potency of these peptides in mesenteric artery smooth muscle cells (VSMCs) and the specific RAMP that mediates the effect of ADM in VSMCs. VSMCs, with or without RAMP knockdown, were treated with CALCB, ADM, or ADM2 in the presence or absence of their antagonists, CALCB8-37, ADM22-52, and ADM217-47, respectively, to assess the relative effect of peptides on cAMP production and their pharmacologic potency. Proximity ligation assay was used to assess the specific RAMP that associates with CALCRL to mediate the actions of ADM in VSMCs. All three peptides induced cAMP generation in VSMCs and the order of their potency is CALCB > ADM > ADM2. Effects of CALCB were blocked by CALCB8-37, ADM effects were blocked by CALCB8-37 and ADM217-47 but not ADM22-52, and ADM2 effects were blocked by all three antagonists. Knockdown of RAMP2 was ineffective, whereas knockdown of RAMP3 inhibited ADM-induced cAMP production in VSMCs, suggesting involvement of RAMP3 with CALCRL to mediate ADM effects. Absence of both RAMP2 and RAMP3 further increased CALCB-induced cAMP synthesis compared to control (P < 0.05). ADM increased CALCRL and RAMP3 association and RAMP3 knockdown inhibited the interaction of ADM with CALCRL.

Effects of intermedin on proliferation, apoptosis and the expression of OPG/RANKL/M-CSF in the MC3T3-E1 osteoblast cell line

Bone remodeling is a vital physiological process of healthy bone tissue in humans. It is characterized by the formation of bone by osteoblasts and its resorption by osteoclasts, and the bone resorbed by osteoclasts is replaced through the differentiation and activity of osteoblasts. Imbalances in this vital process lead to pathological conditions, including osteoporosis. Intermedin (IMD) as a newly discovered peptide in the calcitonin (CT) family of peptides, which shares similar functions with CT, calcitonin gene‑related peptide and amylin in bone resorption. However, the mechanism underlying its effect remains to be elucidated. This was investigated in the present study using the osteoblastic MC3T3‑E1 cell line, which was treated with different doses of IMD (0, 1, 10 and 100 nM). Cell proliferation, apoptosis and the expression of receptor activator of NF‑κB ligand (RANKL), osteoprotegerin (OPG) and macrophage colony‑stimulating factor (M‑CSF) were measured following treatment using multiple detection techniques, including an MTT assay, flow cytometry, reverse transcription‑quantitative polymerase chain reaction and western blot analysis. The resulting data demonstrated that IMD significantly inhibited the apoptosis of MC3T3‑E1 cells induced by serum‑free culture and dexamethasone, however, no significant effects on MC3T3‑E1 cell proliferation were observed. IMD had additional functions on the MC3T3‑E1 cells, including inhibition of the expression of RANKL and M‑CSF, and promotion of the expression of OPG. Previous studies have also demonstrated that RANKL and M‑CSF are two vital factor produced by osteoblasts to promote the maturation and differentiation of osteoclasts, and it has been reported that IMD can inhibit the osteoclast formation stimulated by RANKL and M‑CSF. Together with these findings, the present study concluded that IMD reduces bone resorption by inhibiting osteoblast apoptosis, decreasing the RANKL/OPG ratio and the expression of M-CSF, and inhibiting osteoclast maturation and differentiation.

Adrenomedullin2 (ADM2)/intermedin (IMD) in rat ovary: changes in estrous cycle and pregnancy and its role in ovulation and steroidogenesis

Adrenomedullin2 (ADM2) is reported to facilitate embryo implantation and placental development. Therefore, the current study was undertaken to identify if ADM2 has a functional role in ovary to facilitate its reproductive actions. This study shows that the expression of ADM2 is differentially regulated in rat estrous cycle and that ADM2 increases the synthesis and secretion of 17beta-estradiol accompanied with an increase in the expression of steroidogenic factor 1 (Sf1), estrogen receptor Esr1, and enzymes involved in steroidogenesis in equine chorionic gonadotropin (eCG)-treated rat ovaries. In addition, inhibition of endogenous ADM2 function in eCG-treated immature rats caused impaired ovulation. Furthermore, the mRNA expression of Adm2 and receptor activity modifying protein 3 is higher in the ovary on Day 18 compared to nonpregnant and pregnant rats on Day 22. ADM2-like immunoreactivity is localized in granulosa cells, blood vessels, oocytes, cumulous oophorus, and corpus luteum of pregnant ovaries, suggesting a potential role for ADM2 in the ovary. This is supported by the presence of ADM2-like immunoreactivity in the corpus luteum during pregnancy and a decline in aromatase immunoreactivity in corpus luteum on Day 9 of gestation in rats infused with ADM2 antagonist during implantation and decidualization phase. Taken together, this study suggests a potential involvement of ADM2 in the rat ovary in regulating synthesis of estradiol to support ovulation and facilitate efficient implantation and placental development for a successful pregnancy.

LIMK1 regulates human trophoblast invasion/differentiation and is down-regulated in preeclampsia

Successful human pregnancy requires extensive invasion of maternal uterine tissues by the placenta. Invasive extravillous trophoblasts derived from cytotrophoblast progenitors remodel maternal arterioles to promote blood flow to the placenta. In the pregnancy complication preeclampsia, extravillous trophoblasts invasion and vessel remodeling are frequently impaired, likely contributing to fetal underperfusion and maternal hypertension. We recently demonstrated in mouse trophoblast stem cells that hypoxia-inducible factor-2 (HIF-2)-dependent Lim domain kinase 1 (LIMK1) expression regulates invasive trophoblast differentiation by modulating the trophoblast cytoskeleton. Interestingly, in humans, LIMK1 activity promotes tumor cell invasion by modulating actin and microtubule integrity, as well as by modulating matrix metalloprotease processing. Here, we tested whether HIF-2α and LIMK1 expression patterns suggested similar roles in the human placenta. We found that LIMK1 immunoreactivity mirrored HIF-2α in the human placenta in utero and that LIMK1 activity regulated human cytotrophoblast cytoskeletal integrity, matrix metallopeptidase-9 secretion, invasion, and differentiation in vitro. Importantly, we also found that LIMK1 levels are frequently diminished in the preeclampsia setting in vivo. Our results therefore validate the use of mouse trophoblast stem cells as a discovery platform for human placentation disorders and suggest that LIMK1 activity helps promote human placental development in utero.

Intermedin as a prognostic factor for major adverse cardiovascular events in patients with ST-segment elevation acute myocardial infarction

Intermedin functions systemically as a potent vasodilator and its plasma levels have been shown to be elevated in patients with acute myocardial infarction. This study aimed to evaluate the prognostic value of plasma intermedin level in the patients with ST-segment elevation acute myocardial infarction. Plasma intermedin concentrations of 128 patients and 128 healthy controls were determined using a radioimmunoassay. Patients were followed up for 6 months for major adverse cardiovascular events (MACE) consisting of cardiovascular mortality, reinfarction, hospitalization for decompensated heart failure, and lift-threatening arrhythmia. The association of plasma intermedin levels with MACE was investigated by univariate and multivariate analyses. Plasma intermedin levels were significantly higher in patients than in healthy subjects. Elevated plasma level of intermedin was identified as an independent predictor of MACE. Receiver operating characteristic curve analysis showed that plasma intermedin levels had high predictive value for MACE. Moreover, its predictive value was similar to Global Registry of Acute Coronary Events scores' based on area under curve. Meantime, it obviously improved Global Registry of Acute Coronary Events scores' predictive value in a combined logistic-regression model. In multivariate Cox's proportional hazard analysis, plasma intermedin level emerged as an independent predictor of MACE-free survival. Thus, our results suggest that high plasma intermedin level is associated with poor outcomes of patients and may be a useful prognostic biomarker in ST-segment elevation acute myocardial infarction.

Calcitonin gene related family peptides: importance in normal placental and fetal development

Synchronized molecular and cellular events occur between the uterus and the implanting embryo to facilitate successful pregnancy outcome. Nevertheless, the molecular signaling network that coordinates strategies for successful decidualization, placentation and fetal growth are not well understood. The discovery of calcitonin/calcitonin gene-related peptides (CT/CGRP) highlighted new signaling mediators in various physiological processes, including reproduction. It is known that CGRP family peptides including CGRP, adrenomedulin and intermedin play regulatory functions during implantation, trophoblast proliferation and invasion, and fetal organogenesis. In addition, all the CGRP family peptides and their receptor components are found to be expressed in decidual, placental and fetal tissues. Additionally, plasma levels of peptides of the CGRP family were found to fluctuate during normal gestation and to induce placental cellular differentiation, proliferation, and critical hormone signaling. Moreover, aberrant signaling of these CGRP family peptides during gestation has been associated with pregnancy disorders. It indicates the existence of a possible regulatory role for these molecules during decidualization and placentation processes, which are known to be particularly vulnerable. In this review, the influence of the CGRP family peptides in these critical processes is explored and discussed.

Alterations in deoxyribonucleic acid (DNA) methylation patterns of Calca, Timp3, Mmp2, and Igf2r are associated with chronic cystitis in a cyclophosphamide-induced mouse model

OBJECTIVE

To determine whether epigenetic changes occur during cyclophosphamide-induced chronic bladder inflammation in mice.

MATERIALS AND METHODS

Epigenetic changes play a role in the regulation of inflammatory genes in noncancer diseases such as asthma and chronic obstructive pulmonary disease. However, epigenetic (deoxyribonucleic acid [DNA] methylation) changes during chronic bladder inflammation have not been previously described. Chronic cystitis was induced in 3 groups of adult CD-1 male mice using multiple weight-based intraperitoneal cyclophosphamide injections during a 3-month period. Histopathologic and MethyLight assays were performed on specimens with chronic bladder inflammation at multiple points to monitor cystitis progression and DNA methylation changes compared with the control specimens.

RESULTS

Histopathologic analysis showed the most extensive edema and urothelial sloughing at the 1-month point. MethyLight analyses revealed statistically significant changes in DNA methylation associated with the Calca, Timp3, Mmp2, and Igf2r genes in the chronic bladder injury model. The changes in DNA methylation associated with chronic cystitis were DNA hypomethylation of the Calca gene in the control tissue and DNA hypermethylation for the Calca, Timp3, Mmp2, and Igf2r genes compared with that in the control tissue.

CONCLUSION

DNA methylation changes were noted in the Calca, Timp3, Mmp2, and Igf2r genes during chronic cystitis in a murine model. Epigenetic changes appear to play a role in the regulation of inflammatory bladder genes during chronic cystitis; however, additional studies are needed to elucidate the pathways associated with these genes.

Intermedin attenuates LPS-induced inflammation in the rat testis

First reported as a vasoactive peptide in the cardiovascular system, intermedin (IMD), also known as adrenomedullin 2 (ADM2), is a hormone with multiple potent roles, including its antioxidant action on the pulmonary, central nervous, cardiovascular and renal systems. Though IMD may play certain roles in trophoblast cell invasion, early embryonic development and cumulus cell-oocyte interaction, the role of IMD in the male reproductive system has yet to be investigated. This paper reports our findings on the gene expression of IMD, its receptor components and its protein localization in the testes. In a rat model, bacterial lippolysaccharide (LPS) induced atypical orchitis, and LPS treatment upregulated the expression of IMD and one of its receptor component proteins, i.e. receptor activity modifying protein 2 (RAMP2). IMD decreased both plasma and testicular levels of reactive oxygen species (ROS) production, attenuated the increase in the gene expression of the proinflammatory cytokines tumor necrosis factor alpha (TNFα), interleukin 6 (IL6) and interleukin 1 beta (IL1β), rescued spermatogenesis, and prevented the decrease in plasma testosterone levels caused by LPS. The restorative effect of IMD on steroidogenesis was also observed in hydrogen peroxide-treated rat primary Leydig cells culture. Our results indicate IMD plays an important protective role in spermatogenesis and steroidogenesis, suggesting therapeutic potential for IMD in pathological conditions such as orchitis.

Cigarette smoke-induced placental adrenomedullin expression and trophoblast cell invasion

Smoking in pregnancy reduces preeclampsia risk, but the mechanism of this effect is unknown. Prior studies have demonstrated that women with preeclampsia have lower placental adrenomedullin (AM) expression, and cigarette smoke extract (CSE) treatment of placental trophoblast cells in culture increases AM cellular production. We hypothesized that CSE alters trophoblast invasion through an AM-mediated mechanism, and that placental AM expression is greater among smokers. HTR-8/SVneo trophoblast cells were incubated for 24 hours in Matrigel-invasion chambers with 6 treatment groups: nonstimulated (NS), AM, AM inhibitor (AM22-52), 1% CSE, AM + AM22-52, and 1% CSE + AM22-52. Cells that penetrated the lower surface of the chambers were quantified, invasion indices were calculated, and compared using a 1-way analysis of variance with Bonferroni corrections for multiple comparisons. Trophoblast cells treated with both AM and 1% CSE demonstrated increased cellular invasion compared to NS controls (1.5-fold [P < .01] and 1.45-fold [P < .01], respectively). Cotreatment with the AM inhibitor significantly attenuated the increased invasion seen with both AM and CSE alone. Next, the placental tissue was obtained from 11 smokers and 11 nonsmokers at term and processed for immunohistochemistry (IHC) and real-time quantitative polymerase chain reaction (PCR) for AM. Placentas from smokers demonstrated more intense AM staining and increased AM gene (ADM) expression compared to placentas from nonsmokers (P = .004 for IHC, P = .022 for PCR). The CSE increases trophoblast cell invasion through an AM-mediated process, and placental AM expression is increased among term smokers compared to nonsmokers. These findings provide evidence that the AM pathway may play a role in the protection from preeclampsia seen in smokers.

Intermedin in rat uterus: changes in gene expression and peptide levels across the estrous cycle and its effects on uterine contraction

BACKGROUND

The present study demonstrates the expression of intermedin (IMD) and its receptor components in the uterus of the female rat during the estrous cycle and its effect on uterine contraction.

METHODS

The gene expression level of intermedin and its receptor components and the peptide level of intermedin were studied by real-time RT-PCR and enzyme immunoassay (EIA) respectively. The separation of precursor and mature IMD was studied by gel filtration chromatography and EIA. The localization of IMD in the uterus was investigated by immunohistochemistry. The effect of IMD on in vitro uterine contraction was studied by organ bath technique.

RESULTS

Uterine mRNAs of Imd and its receptor components and IMD levels displayed cyclic changes across the estrous cycle. Imd mRNA level was the highest at proestrus while the IMD level was the highest at diestrus. IMD was found in the luminal and glandular epithelia and IMD treatment significantly reduced the amplitude and frequency of uterine contraction but not the basal tone. Both calcitonin gene-related peptide (CGRP) receptor antagonist hCGRP8-37 and adrenomedullin (ADM) receptor antagonist hADM22-52 partially abolished the inhibitory effect of IMD on uterine contraction while the specific IMD receptor antagonist hIMD17-47 completely blocked the actions. The enzyme inhibitors of NO (L-NAME) and PI3K (Wortmannin) pathways diminished the IMD effects on uterine contraction while the cAMP/PKA blocker, KT5720, had no effect, indicating an involvement of NO and PI3K/Akt but not PKA.

CONCLUSIONS

IMD and the gene expression of its receptor components are differentially regulated in the uterus during the estrous cycle and IMD inhibits uterine contraction by decreasing the amplitude and frequency.

Intermedin/adrenomedullin 2 is associated with implantation and placentation via trophoblast invasion in human pregnancy

RATIONALE

Intermedin (IMD) is a novel peptide expressed in trophoblast cells in human placenta and enhances the invasion, migration, and human leukocyte antigen class I, G (HLA-G) expression in first-trimester HTR-8SV/neo cells. We recently reported that infusion of IMD antagonist in pregnant rats is detrimental to pregnancy outcome, resulting in impaired fetoplacental growth and deformed placental vasculature.

OBJECTIVE

This study was undertaken to assess expression of IMD and its involvement in human implantation and early placentation and assess whether its expression is altered in spontaneous abortion.

FINDINGS AND CONCLUSIONS

We demonstrate for the first time that IMD is present in day 5 embryonic secretome; villous and decidual expression of IMD is higher at 6-8 weeks after a decline as gestation advances toward the second trimester; first-trimester spontaneous abortion is associated with a lower expression of IMD in serum, villi, and decidua; IMD stimulates the invasive capacity of first-trimester primary Extravillous cytotrophoblast cells; and IMD decreases elevated levels of tumor suppressor Kangia-1 in decidual explants from first-trimester spontaneous abortion. In conclusion, this study is the first to demonstrate a potential involvement of IMD in human embryo implantation and placental development via regulation of trophoblast invasion at the maternal-fetal interface and suggests a physiological role for this novel peptide in establishment of human pregnancy.

Intermedin is overexpressed in hepatocellular carcinoma and regulates cell proliferation and survival

Angiogenesis is one of the hallmarks of tumor growth and metastasis. Identification of tumor angiogenic factors has been a critical component in understanding cancer biology and treatment. Intermedin (IMD) has been reported to promote angiogenesis in a rat ischemic model and human umbilical vascular endothelial cells. Our study sought to determine the role of IMD in human hepatocellular carcinoma tumor progression. High IMD mRNA expression levels were observed in human hepatocellular carcinoma tumors, even in early stage disease, by real-time RT-PCR. Immunohistochemical analysis of hepatocellular carcinoma clinical samples demonstrated that the tumor regions were significantly more immunoreactive for IMD than adjacent benign liver. Inhibition of IMD expression using RNA interference reduced cell proliferation in SK-Hep-1 and SNU-398 cells. Blockage of IMD signaling using either an antagonist peptide or a neutralizing antibody inhibited growth in a dose-dependent manner with concomitant induction of apoptosis, causing cleavage of caspase-8 and downregulation of Gli1 and Bcl2. Conversely, addition of IMD active peptide increased the phosphorylation level of extracellular signal-regulated kinase. Thus, IMD might play an important role in cell proliferation and survival of hepatocellular carcinoma. Our data suggests that IMD is a potential biomarker and therapeutic target for hepatocellular carcinoma.

Regulation of trophoblast invasion: the role of matrix metalloproteinases

Pregnancy success is determined by a complex progress that includes trophoblast invasion and placentation. Matrix metalloproteinases (MMPs) and tissue inhibitors of metalloproteinases (TIMPs) are metal-dependent endopeptidases capable of degrading extracellular matrix, and appear to play a critical role in trophoblast invasion. This article reviews in detail the role of MMPs, TIMPs, and their regulators in the mechanism of trophoblast invasion in early human pregnancy.

Low calcitonin receptor like receptor expression in endometrial vessels from women with unexplained infertility

Adrenomedullin (AM) and its receptor subunit, calcitonin receptor-like receptor (CLR) are known to be important for endothelial function. The genotypes and phenotypes of AM and CLR in the endometrium were studied in relation to unexplained infertility. Endometrial biopsies from 12 fertile and 11 infertile women and blood samples from 156 fertile and 106 infertile women were collected. Protein and mRNA expression of AM and CLR was determined using immunohistochemistry and real time PCR. Allele and genotype frequencies in the AM (rs4399321 and rs7944706) and CLR genes (rs696574, rs1528233 and rs3771073) were performed using Taqman genotyping assays. Unexplained infertility was characterised by lower number of vessels stained with CLR in endometrium compared to fertile controls. There was no difference in AM expression. This could not be explained by SNP analysis in the AM or CLR genes. Imbalance in the AM/CLR system might alter endothelial function in women with unexplained infertility.

Adrenomedullin 2/intermedin regulates HLA-G in human trophoblasts

Adrenomedullin 2 (ADM2), also referred to as intermedin (IMD), is expressed in trophoblast cells in human placenta and enhances the invasion and migration of first-trimester HTR-8SV/neo cells. Further infusion of ADM2 antagonist in pregnant rat causes fetoplacental growth restriction, suggesting a role for ADM2 in maintaining a successful pregnancy. This study was undertaken to assess whether ADM2 protein is present in decidual tissue and colocalized with HLA-G-positive cytotrophoblast cells and natural killer cells; to assess whether ADM2 regulates expression of HLA-G in trophoblast cells; and to identify whether mitogen-activated protein kinase (MAPK) signaling pathway is involved in ADM2-induced trophoblast cell invasion and migration. Using immunohistochemical methods and RT-PCR, this study shows that ADM2 protein is colocalized with HLA-G-expressing cytotrophoblast cells as well as with NCAM1 (CD56) immunoreactivity in human first-trimester decidual tissue, and that ADM2 mRNA is expressed in peripheral blood natural killer cells. Further, ADM2 dose dependently increases the expression of HLA-G antigen in HTR-8SV/neo cells as well as in term placental villi explants, suggesting involvement of ADM2 in the regulation of HLA-G in trophoblast cells. In addition, interference with the activity of RAF and MAPK3/1 by their inhibitors, manumycin and U0126, respectively, reduces ADM2-induced HTR-8SV/neo cell invasion and migration. In summary, this study suggests a potential involvement for ADM2 in regulating HLA-G antigen at the maternal-fetal interface in human pregnancy and facilitating trophoblast invasion and migration via MAPK3/1 phosphorylation.

Potential role of intermedin/adrenomedullin 2 in early embryonic development in rats

Adrenomedullin2 (ADM2), also referred to as Intermedin (IMD) is expressed in trophoblast cells in human placenta and enhances the invasion and migration of first trimester HTR-8/SV-neo cells. Recently we demonstrated that infusion of IMD antagonist in pregnant rats causes feto-placental growth restriction suggesting a role for IMD in maintaining a successful pregnancy. Therefore, this study was undertaken to assess if IMD has a functional role in embryo implantation in a rat model. We show that IMD mRNA is expressed in rat implantation sites and its expression is significantly higher on day 15 in placenta compared to days 18-22. Infusion of IMD antagonist IMD₁₇₋₄₇ from day 3 of pregnancy causes a significant decrease in the weights of day 9 implantation sites as well as serum levels of 17β-estradiol, progesterone, nitric oxide and serum MMP2 and MMP9 gelatinase activity. Further, expression of MMP2, MMP9, VEGF and PLGF protein levels are significantly downregulated in the implantation sites of IMD antagonist treated rats. This study suggests a potential involvement of IMD in regulating the factors that are critical for implantation and growth of the embryo and thus in establishment of normal rat pregnancy.