Adrenomedullin 2/intermedin regulates HLA-G in human trophoblasts

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.

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.

Natural killer-cell deficiency alters placental development in rats

Natural killer (NK) cells are the most prevalent leukocyte population in the uterus during early pregnancy. Natural killer cells contribute to uterine vascular (spiral artery) remodeling in preparation for the increased demand on these vessels later in pregnancy. A second wave of spiral artery modification is directed by invasive trophoblast cells. The significance of the initial wave of NK-cell-mediated vascular remodeling in species exhibiting deep trophoblast invasion such as humans and rats is not known. The purpose of this study was to generate a genetic model of NK-cell deficiency in rats, and determine the consequences of NK-cell deficiency on spiral artery remodeling and reproductive outcomes. To accomplish this task, we utilized zinc finger nuclease-mediated genome editing of the rat interleukin-15 (Il15) gene. Il15 encodes a cytokine required for NK-cell lineage development. Using this strategy, a founder rat was generated containing a frameshift deletion in Il15. Uteri of females harboring a homozygous mutation at the Il15 locus contained no detectable NK cells. NK-cell deficiency did not impact fetal growth or viability. However, NK-cell deficiency caused major structural changes to the placenta, including expansion of the junctional zone and robust, early-onset activation of invasive trophoblast-guided spiral artery remodeling. In summary, we successfully generated an NK-cell-deficient rat and showed, using this model, that NK cells dampen the extent of trophoblast invasion and delay trophoblast-directed spiral artery remodeling. This study furthers our understanding of the role of NK cells on uterine vascular remodeling, trophoblast invasion, and placental development.

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.

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.

Leptin promotes HLA-G expression on placental trophoblasts via the MEK/Erk and PI3K signaling pathways

INTRODUCTION

The development of the human haemochorial placenta requires complex regulatory mechanisms to protect invasive trophoblast cells from cytotoxic responses elicited by maternal immune cells. Leptin, the adipocyte derived hormone encoded by the Lep gene, is synthesized by placental trophoblasts and exerts pleiotropic effects on the immune system, including the promotion of inflammation and the activation of T cell responses.

METHODS

To address its possible involvement in the modulation of maternal immune responses during pregnancy, we investigated the effect of leptin on the expression of the class Ib histocompatibility antigen HLA-G as one of the chief immunosuppressive strategies used by trophoblast cells.

RESULTS

In vitro incubation of the trophoblast derived Swan 71 and JEG-3 cell lines with 25-50 ng/ml recombinant leptin significantly boosted HLA-G mRNA and protein expression, and this effect was abrogated upon pharmacological inhibition of the PI3K-Akt and MEK-Erk signaling pathways. A similar stimulatory effect of leptin was observed in term placental tissue explants, though 10-fold higher doses were required for stimulation. Further, JEG-3 cells treated with a leptin antisense oligodeoxynucleotide displayed decreased HLA-G expression levels, which were partially recovered by addition of stimulating doses of exogenous hormone. Immunofluorescence and qPCR analysis confirmed leptin biosynthesis in placental tissue, further showing that invasive extravillous trophoblast cells were a main source of this hormone during the first trimester of normal pregnancies.

DISCUSSION

Taken together, our results show that leptin acts as an autocrine/paracrine signal promoting HLA-G expression in placental trophoblasts suggesting an important role in the regulation of immune evasion mechanisms at the fetal maternal interface.

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.

Adrenomedullin and endocrine control of immune cells during pregnancy

The immunology of pregnancy is complex and incompletely understood. Aberrant immune activity in the decidua and in the placenta is believed to play a role in diseases of pregnancy, such as infertility, miscarriage, fetal growth restriction and preeclampsia. Here, we briefly review the endocrine control of uterine natural killer cell populations and their functions by the peptide hormone adrenomedullin. Studies in genetic animal models have revealed the critical importance of adrenomedullin dosage at the maternal-fetal interface, with cells from both the maternal and fetal compartments contributing to essential aspects underlying appropriate uterine receptivity, implantation and vascular remodeling of spiral arteries. These basic insights into the crosstalk between the endocrine and immune systems within the maternal-fetal interface may ultimately translate to a better understanding of the functions and consequences of dysregulated adrenomedullin levels in clinically complicated pregnancies.

Effect of mesenchymal stem cells and extracts derived from the placenta on trophoblast invasion and immune responses

Tightly regulated trophoblast invasion and immunomodulation at the feto-maternal interface is important during implantation and fetal development. Although trophoblasts as a pregnancy-specific cell has been reported to be a key factor capable of regulating certain events during implantation, however, its regulatory mechanisms are still unclear. In this study, we analyzed the effects of chorionic plate-derived mesenchymal stem cells (CP-MSCs) and human placenta extract (hPE) isolated from human normal placentas on trophoblasts invasion and immune responses. We investigated the effects of CP-MSCs, hPE treatment, and their combination on trophoblasts invasion and on T-cells suppression through human leukocyte antigen-G (HLA-G) expression. Trophoblasts invasion was significantly increased by co-culture of CP-MSCs or by hPE treatment (P<0.05), and enhanced by the combination of CP-MSCs and hPE treatment (P<0.05). The proliferation of T-cells was decreased by co-culture of CP-MSCs and hPE treatment, whereas the population of regulatory T-cells was increased (P<0.05). Also, the dynamics alterations of multiple cytokines were observed in the culture supernatants of trophoblasts and T-cells depending on CP-MSCs co-culture and hPE treatment. Interestingly, the concentration of soluble HLA-G was increased by CP-MSCs co-culture, by hPE treatment and by combination of them on trophoblasts and activated T-cells (P<0.05). These findings suggested that CP-MSCs and hPE can regulate trophoblasts invasion and T-cell by alteration of HLA-G expression. These results will provide understandings of trophoblasts invasion and the immunological network at the feto-maternal interface during pregnancy and contribute to the foundation of a new treatment strategy for pregnancy disorders.

Proteomic analysis of knock-down HLA-G in invasion of human trophoblast cell line JEG-3

Previous studies showed that aberrant HLA-G expression in trophoblast cells plays important roles in trophoblast invasion; however, the mechanisms remain to be explored. In this study, we found that suppressed HLA-G expression could dramatically decrease the mRNA and protein expression levels of matrix metalloproteinase 2 and matrix metalloproteinase 9, and in the proteome assay, there were 3 identified proteins namely, prefoldin 1, eukaryotic translation elongation factor 2 and malate dehydrogenase 2, which were verified by Western blot and known to be associated with invasion, cell cycle and cell metabolism, respectively. Collectively, our study indicated a potential involvement of HLA-G in autocrine networks that may regulate prefoldin, MMPs and trophoblast invasion at the maternal-fetal interface in human pregnancy.

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.

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.

The immunosuppressive molecule HLA-G and its clinical implications

Human leukocyte antigen G (HLA-G) is a non-classical major histocompatibility complex (MHC) class I molecule that, through interaction with its receptors, exerts important tolerogenic functions. Its main physiological expression occurs in placenta where it seems to participate in the maternal tolerance toward the fetus. HLA-G has been studied as a marker of pregnancy complications such as abortion or pre-eclapmsia. Although HLA-G is not expressed in most adult tissues, its ectopic expression has been observed in some diseases such as viral infections, autoimmune disorders, and especially cancer. HLA-G neo-expression in cancer is associated with the capability of tumor cells to evade the immune control. In this review, we will summarize HLA-G biology and how it participates in these physiopathological processes. Special attention will be paid to its role as a diagnostic tool and also as a therapeutic target.