Expression of Thyroid Hormone Receptors in Villous Trophoblasts and Decidual Tissue at Protein and mRNA Levels Is Downregulated in Spontaneous and Recurrent Miscarriages

Thyroid hormone transport and metabolism are disturbed in the placental villi of miscarriage

BACKGROUND

It has been long known that thyroid hormone regulates placental villi development, which is associated with the occurrence of miscarriage. However, whether abnormal thyroid hormone metabolism and transport in placental villi are involved in miscarriage is still to be verified.

METHODS

Placental villi of elective terminations of pregnancies (ETPs) and miscarriage were collected. Proliferative activity and apoptosis of villi trophoblasts and angiogenesis were detected by TUNEL and immunochemistry. The expressions of thyroid hormone receptors (THRs), transthyretin (TTR), monocarboxylate transporter 8 (MCT8), organic anion transporting polypeptides 1A1 (OATP1A1), deiodinase 2 (Dio2) and Dio3 were examined by RT-PCR, Western blot, immunohistochemistry and immunofluorescence. JEG3 cell was treated with iopanoic acid (IOP), an inhibitor of Dio2 activity, the expressions of Dio2, placenta growth factor (PLGF) and sFlt1 were detected by RT-PCR and Western blot.

RESULTS

Cell proliferation was suppressed and apoptosis was increased in placental villi cytotrophoblasts of miscarriage. CD34+ vessel number and vascular endothelial growth factor (VEGF) protein abundance were decreased in miscarriage. In miscarriage group, the gene expression of Dio2, Dio3, TTR and THRα, but not THRβ, MCT8 and OATP1A1, were downregulated. The protein abundances of TTR and THRα were downregulated in miscarriage group, but not THRβ. The protein abundance of Dio2 in miscarriage villi was decreased compared with that in ETP. In JEG3 cells, the gene expression of PLGF was decreased and the expression of sFlt1 was increased in IOP treatment; The protein abundance of Dio2 was downregulated but the gene expression of Dio2 was unaffected in IOP treatment.

CONCLUSION

Thyroid hormone transport and metabolism in miscarriage were disturbed and may impaired angiogenesis of placental villi, which was associated with the occurrence of miscarriage.

Thyroid hormones: Metabolism and transportation in the fetoplacental unit

The thyroid hormones (THs), thyroxine (T4) and triiodothyronine (T3), are of vital importance for fetal development. The concentration of THs in fetal circulation varies throughout gestation and differs from the concentration in the maternal serum, indicating the presence of maternal-fetal thyroid homeostasis regulatory mechanisms in the placenta. The passage of THs from maternal circulation to fetal circulation is modulated by plasma membrane transporters, enzymes, and carrier proteins. Monocarboxylate transporter 8, iodothyronine deiodinases (DIO2 and DIO3), and transthyretin are especially involved in this maternal-fetal thyroid modulation, shown by a greater expression in the placenta. THs also play a role in placental development and as expected, abnormal variations in TH levels are associated with pregnancy complications and can result in damage to the fetus. Although new evidence regarding TH regulation during pregnancy and its effects in the mother, placenta, and fetus has been published, many aspects of these interactions are still poorly understood. The objective of this review is to provide an evidence-based update, drawn from current data, on the metabolism and transport of THs in the placenta and their vital role in the maternal-fetal relationship.

Gaps in the knowledge of thyroid hormones and placental biology

Thyroid hormones (THs) are required for the growth and development of the foetus, stimulating anabolism and oxygen consumption from the early stages of pregnancy to the period of foetal differentiation close to delivery. Maternal changes in the hypothalamic–pituitary thyroid axis are also well known. In contrast, several open questions remain regarding the relationships between the placenta and the maternal and foetal TH systems. The exact mechanism by which the placenta participates in regulating the TH concentration in the foetus and mother and the role of TH in the placenta are still poorly studied. In this review, we aim to summarize the available data in the area and highlight significant gaps in our understanding of the ontogeny and cell-specific localization of TH transporters, TH receptors and TH metabolic enzymes in the placenta in both human and rodent models. Significant deficiencies also exist in knowledge of the contribution of genomic and nongenomic effects of TH on the placenta and finally how the placenta reacts during pregnancy when the mother has thyroid disease. By addressing these key knowledge gaps, improved pregnancy outcomes and management of women with thyroid alterations may be possible.

The role of Interleukin-18 in recurrent early pregnancy loss

BACKGROUND

A successful pregnancy is a unique and complex immunological state. Cytokines seem to be crucial for the implementation of a tolerogenic environment at the feto-maternal interphase towards the semi-allogenic fetus. Importantly, the switch from a Th1- to a Th2 cytokine profile might play a key role. Interestingly, Interleukin-18 (IL-18) can induce either Th1 or Th2 immune response depending on the local cytokine environment. Therefore, this study investigates the expression of IL-18 in early pregnancy loss.

PATIENTS AND METHODS

The TaqMan® Human Cytokine Network Array was carried out with placental tissue of patients with healthy pregnancies (n = 15) and recurrent miscarriage (n = 15) in order to investigate differences in IL-18 mRNA expression. Immunohistochemical staining was applied to examine the IL-18 protein expression in the syncytiotrophoblast and decidua of healthy pregnancies (n = 15), spontaneous (n = 12) and recurrent miscarriage (n = 9). The characterization of IL-18 expressing cells in the decidua was evaluated by double-immunofluorescence. Correlation analysis between IL-18 protein expression and clinical data of the study population was performed via spearman correlation coefficient.

RESULTS

Gene expression analysis revealed a 4,9-times higher expression of IL-18 in recurrent miscarriage patients. IL-18 protein expression was significantly upregulated only in the decidua in the recurrent miscarriage group (p = 0.031). We did not observe significant changes of IL-18 protein expression in spontaneous miscarriage specimens when compared to healthy controls (p = 0.172). Double-immunofluorescence identified decidual stroma cells as IL-18 expressing cells. Correlation analysis showed a significant negative correlation of IL-18 protein expression and gestational age in healthy controls (r = -,745, p = 0.034). Also, a positive correlation of IL-18 and maternal age was observed in patients suffering from recurrent pregnancy loss (r =, 894, p = 0.041).

CONCLUSION

Our results indicate that IL-18 expression might be necessary in early gestation but requires a tight regulation for a successful ongoing pregnancy. In the present study we observed that a significant upregulation of IL-18 in the decidua was restricted to patients with recurrent miscarriage and therefore might be interesting as a diagnostic marker. Further studies need to evaluate the exact pathophysiological mechanisms.

Effect of Thyromimetic GC-1 Selective Signaling on Reproductive and Lactational Performance in the Hypothyroid Rat

INTRODUCTION

The potential of the thyroid hormone receptor β (TRβ1) selective analog GC-1 has been widely proven in animal models and humans. However, its effect on the reproductive stage of the female rat has not been evaluated.

METHODS

The effect of the administration of GC-1 or equimolar doses of triiodothyronine (T3) was evaluated on the reproductive performance of the hypothyroid female rat and the indirect effect on pup thyroid status, weight, and survival.

RESULTS

Hypothyroidism reduced the number of embryos implanted in the uterus, whereas T3 and GC-1 treatment in hypothyroid females reestablished the number of implanted embryos to normal. Initiation of labor was delayed by hypothyroidism, and T3 replacement treatment reinstated the normal timing of parturition. The administration of GC-1 alone to the lactating mother did not affect pup survival, weight, or thyroidal status.

CONCLUSIONS

Our findings show the differential effect of thyroid hormone selective signaling during gestation and the indirect exposure of the pups; we also emphasize the plausible use of GC-1 for treatment of hypothyroid mothers during the lactation period.

The interplay between thyroid hormones and the placenta: a comprehensive review†

Thyroid hormones (THs) regulate a number of metabolic processes during pregnancy. After implantation, the placenta forms and enhances embryonic growth and development. Dysregulated maternal THs signaling has been observed in malplacentation-mediated pregnancy complications such as preeclampsia, miscarriage, and intrauterine growth restriction (IUGR), but the molecular mechanisms involved in this association have not been fully characterized. In this review, we have discussed THs signaling and its roles in trophoblast proliferation, trophoblast differentiation, trophoblast invasion of the decidua, and decidual angiogenesis. We have also explored the relationship between specific pregnancy complications and placental THs transporters, deiodinases, and THs receptors. In addition, we have examined the effects of specific endocrine disruptors on placental THs signaling. The available evidence indicates that THs signaling is involved in the formation and functioning of the placenta and serves as the basis for understanding the pathogenesis and pathophysiology of dysthyroidism-associated pregnancy complications such as preeclampsia, miscarriage, and IUGR.

The decidual expression of Interleukin-7 is upregulated in early pregnancy loss

BACKGROUND

Maternal immunological rejection of the semi-allogenic fetus is discussed as one of the significant factors involved in early pregnancy loss. An array of cytokines secreted by both maternal and fetal cells is involved in generating a delicate maternal immune tolerance. Interleukin-7 (IL-7) is discussed to play a key role in pro-inflammatory processes, but there is still limited insight into the pathophysiological input on placentation and embryonic development in early pregnancy loss.

PATIENTS AND METHODS

Cytokine level differences were identified with quantitative real-time PCR in placental tissue from spontaneous abortions (SA) (n = 18), recurrent spontaneous abortions (RSA) (n = 15), and healthy pregnancies (n = 15) at gestational weeks 7 to 14. Protein expression of IL-7 in the decidua was investigated by immunohistochemistry. IL-7-expressing cells were identified with double-immunofluorescence.

RESULTS

Decidua of women with RSA expressed almost 51-times higher values of IL-7 in gene expression analysis. Immunohistochemistry identified a significant upregulation of IL-7 in the decidua of RSA specimens (p = .013) and in the decidua of women with SA (p = .004). Double-immunofluorescence confirmed decidual stroma cells as IL-7-expressing cells.

CONCLUSION

Significantly elevated IL-7 values in the decidua of spontaneous and recurrent miscarriages imply a crucial role of the cytokine in the signaling at the feto-maternal interface of the placenta. An overexpression of IL-7 could result in early pregnancy loss by inducing a pro-inflammatory environment. Proven to be valuable in other autoimmune diseases, targeting IL-7 signaling therapeutically may prove to be a very beneficial treatment option for RSA patients.

The effects of hypothyroidism and hyperthyroidism on placental Hofbauer cells of pregnant rats

We investigated the effects of maternal thyroid disorders on Hofbauer cells of both the placenta and the fetus in pregnant rats. We divided 21 rats into three groups: control group, induced hypothyroidism (hypo) group and induced hyperthyroidism (hyper) group. Hypothyroidism was induced using propylthiouracil and hyperthyroidism was induced using L-thyroxine. We measured maternal weight, maternal free thyroxine, fetal weight, fetal viability and placental morphology. At the end of the experiment, fetuses of the hypo and hyper groups were less developed than those of the control group. In the hypo and hyper groups, the thickness of the labyrinth zone was decreased, but thickness of the basal zone and decidua basalis was increased. The number of Hofbauer cells was increased in both the hypo and hyper groups. Vascular endothelial growth factor expression was increased in both the hypo and hyper groups compared to controls. Our findings indicate that maternal thyroid disorders exert a negative effect on fetal growth and placental development.

Generation and Characterization of a New Resistance to Thyroid Hormone Mouse Model with Thyroid Hormone Receptor Alpha Gene Mutation

Background: In humans, resistance to thyroid hormone (RTH) caused by mutations in the thyroid hormone receptor alpha (THRA) gene, RTHα, manifests as tissue-specific hypothyroidism and circulating thyroid hormone levels exhibit hypothyroid-like clinical features. Before the identification of patients with RTHα, several Thrα1 knock-in mouse models were generated to clarify the function of TRα1. However, the phenotypes of these mice were not consistent with the clinical presentation of RTHα in humans. For the present study, we generated an RTHα mouse model that carries the Thra1E403X mutation found in human RTHα patients. Here, we report the gross phenotypes of this mouse RTHα model. Methods: Traditional homologous recombination gene targeting techniques were used to introduce a mutation (Thra1E403X) in the mouse Thra gene. The phenotypes of the resulting mice were studied and compared with clinical features observed for RTHα with THRAE403X. Results: Thrα1E403X/E403X homozygous mice exhibited severe neurological phenotypes, such as spasticity and motor ataxia, which were similar to those observed in endemic cretinism. Thrα1E403X/+ heterozygous mice reproduced most clinical manifestations of patient with RTHα, such as a normal survival rate and male fertility, as well as delayed postnatal growth and development, neurological and motor coordination deficits, and anemia. The mice had typical thyroid function with a modest increase in serum triiodothyronine (T3) levels, a low thyroxine (T4)/T3 ratio, and low reverse T3 (rT3) levels. Conclusions: The Thrα1E403X/+ mice faithfully recapitulate the clinical features of human RTHα and thus can provide a useful tool to dissect the role of TRα1 in development and to determine the pathological mechanisms of RTHα.

Interleukin-1 beta is significantly upregulated in the decidua of spontaneous and recurrent miscarriage placentas

BACKGROUND

Pregnancy is an extraordinarily complex immunological process. For successful pregnancy maintenance the maternal immune system must adapt to and tolerate the semi-allogenic fetus at the fetomaternal interface of the placenta. This balance is regulated by cytokines with a predominant T helper 2 (Th-2) system and a suppressed inflammatory T helper 1 (Th-1) response. This study investigates the role of the Th-1 pro-inflammatory cytokine Interleukin-1 beta (IL-1β) and its role in early pregnancy loss.

PATIENTS AND METHODS

In order to identify differences in IL- β levels a TaqMan® Human Cytokine Network Array, with placental tissue obtained from patients with healthy pregnancies (n = 15) and recurrent miscarriage (n = 15), was carried out. Protein expression of IL-1β in the decidua of healthy pregnancies (n = 15), spontaneous (n = 18) and recurrent miscarriages (n = 15), was investigated by immunohistochemistry. The identification of IL-1β expressing cells in the decidua was done with double-immunofluorescence.

RESULTS

Gene expression analysis identified a nearly 54-times higher expression of IL-1β in placental tissue of patients suffering from recurrent abortion. Immunohistochemistry confirmed a significant upregulation of IL-1β in the decidua of recurrent miscarriage specimens (p = 0.01) as well as in the decidua of women with spontaneous abortion (p = 0.001). Double-immunofluorescence identified decidual stoma cells as IL-1β expressing cells.

CONCLUSION

Significant upregulation of IL-1β may be associated with an imbalanced immune system and a procoagulant state that could be responsible for early pregnancy loss. These results provide new evidence of the complex interplay of IL-1β at the fetomaternal interface and its crucial role in miscarriage processes.

Pregnancy Zone Protein (PZP) is significantly upregulated in the decidua of recurrent and spontaneous miscarriage and negatively correlated to Glycodelin A (GdA)

BACKGROUND

Pregnancy Zone Protein (PZP) is an immunosuppressive protein that is expressed by the placenta and has also been identified in immune cells. When PZP and Glycodelin A (GdA) are combined, they act synergistically to inhibit Th-1 immune response. Little is known about its combined expression and role in normal and disturbed first trimester pregnancy.

PATIENTS AND METHODS

We investigated the expression of PZP and GdA in placental tissue obtained from spontaneous miscarriage (SM) (n = 19) and recurrent miscarriage (RM) (n = 17) at gestational weeks 6-13 by immunohistochemistry and on mRNA-level by either TaqMan PCR or in situ hybridization. Placental tissue from legal terminations of healthy pregnancies (n = 15) served as control group. Immunofluorescence double staining was used to analyse the combined expression of PZP and GdA in decidual tissue.

RESULTS

The protein level of PZP was significantly increased in decidual stroma of SM samples compared to the decidua of control specimens and also significantly upregulated in the decidual stroma cells in the RM group. Concerning GdA, the decidual stroma revealed a significantly decreased protein level in the group with spontaneous abortions than in the group with healthy pregnancies. There was also a significant downregulation of GdA in the decidual stroma of RM samples compared to the control group. We observed a significant negative correlation of PZP and GdA in decidual stromal tissue of recurrent abortion. We could confirm the staining results for PZP as well as for GdA on mRNA level. Both proteins are co-localized in decidual stroma as analysed by immunofluorescence double staining.

CONCLUSION

A balanced expression of GdA and its carrier protein PZP in the decidua seems crucial for a successful ongoing pregnancy. According to our data, these immunosuppressive proteins are co-localized in the decidual tissue and show a negative correlation only in patients suffering from recurrent abortion.

Cell Type- and Sex-Specific Dysregulation of Thyroid Hormone Receptors in Placentas in Gestational Diabetes Mellitus

Thyroid hormones are essential for development of trophoblasts and the fetus. They also regulate a wide range of metabolic processes. We investigated the influence of maternal gestational diabetes mellitus (GDM) on thyroid hormone receptor (THR) isoforms THRα1, THRα2, THRβ1 and THRβ2 of the human placenta in a sex- and cell-type specific manner. Term placental tissue was obtained from women with (n = 40) or without GDM (control; n = 40). THRs levels were measured by semi-quantitative immunohistochemistry and real-time qRT-PCR. We localized THR immunostaining in syncytiotrophoblast (SCT), which was the tissue with the strongest signal. Double immunofluorescence identified THR in decidual cells in the stroma and in extravillous cytotrophoblasts. GDM did not change THRα1 immunolabelling intensity in decidua, but was associated with a stronger immunolabelling in SCT compared to GDM (p < 0.05). The SCT difference of GDM vs. control was strongest (p < 0.01) in female placentas. THRα2 was only weakly present and immunolabelling was weaker (p < 0.05) in SCT of only male GDM placentas in comparison to male controls. THRβ1/β2 immunostaining was weak in all cell types without changes in GDM. However, more THRβ1/2 protein was present (p < 0.001) in male than female placentas. All these protein changes were paralleled by changes of THR transcript levels. The data show that THR are expressed in term trophoblast in relation to fetal sex. Maternal GDM influences predominantly THRα1 in SCT, with the strongest GDM effect in SCT of female placentas.

Spliceosome protein EFTUD2 is upregulated in the trophoblast of spontaneous miscarriage and hydatidiform mole

BACKGROUND

Elongation factor Tu GTP binding domain containing 2 (EFTUD2) is an alternative splicing factor that modulates cell differentiation and activation processes. EFTUD2 is known to modulate immune responses and mutation of the EFTUD2-gene lead to fetal malformation. Little is known about its expression and role in normal and disturbed first trimester pregnancy.

PATIENTS AND METHODS

We investigated the expression of EFTUD2 in placental tissue obtained from patients with normal (n = 14), spontaneous miscarriage (n = 15) and molar (n = 14) pregnancy by immunohistochemistry. The expression of EFTUD2 was correlated on the protein level with known immune modulatory proteins like pregnancy zone protein (PZP) and in addition with human chorionic gonadotropin (hCG). Furthermore, we analysed the EFTUD2 and PZP expression in vitro after stimulation of the chorioncarcinoma cell line JEG-3 with hCG.

RESULTS

EFTUD2 is significantly upregulated in the syncytiotrophoblast of spontaneous miscarriage (p = 0.003) and molar pregnancy (p = 0.003) compared to week of gestation-adjusted normal first trimester placentas. PZP is negatively correlated (p = 0.021) to EFTUD2 in the syncytiotrophoblast and is therefore significantly downregulated in miscarriage (p = 0.028) and mole pregnancy (p = 0.006). In addition, hCG is positively correlated to EFTUD2 in mole pregnancy. The addition of hCG to chorioncarcinoma cell lines JEG-3 in vitro stimulated EFTUD2 expression in these cells (p = 0.027).

CONCLUSION

Regulation of alternative splicing seems crucial for a successful ongoing pregnancy. The up-regulated elongation factor EFTUD2 may have a critical role in miscarriage.

Thyroid hormones and female reproduction

Thyroid hormones are vital for the proper functioning of the female reproductive system, since they modulate the metabolism and development of ovarian, uterine, and placental tissues. Therefore, hypo- and hyperthyroidism may result in subfertility or infertility in both women and animals. Other well-documented sequelae of maternal thyroid dysfunctions include menstrual/estral irregularity, anovulation, abortion, preterm delivery, preeclampsia, intrauterine growth restriction, postpartum thyroiditis, and mental retardation in children. Several studies have been carried out involving prospective and retrospective studies of women with thyroid dysfunction, as well as in vivo and in vitro assays of hypo- and hyperthyroidism using experimental animal models and/or ovarian, uterine, and placental cell culture. These studies have sought to elucidate the mechanisms by which thyroid hormones influence reproduction to better understand the physiology of the reproductive system and to provide better therapeutic tools for reproductive dysfunctions that originate from thyroid dysfunctions. Therefore, this review aims to summarize and update the available information related to the role of thyroid hormones in the morphophysiology of the ovary, uterus, and placenta in women and animals and the effects of hypo- and hyperthyroidism on the female reproductive system.

Involvement of ILR4α and TLR4 in miscarriages

BACKGROUND

The purpose of this study was to analyze the involvement of signaling via Interleukin-4-Receptor α (IL4Rα) and Toll like receptor (TLR) 4 at the fetomaternal interface in the process of early pregnancy.

PATIENTS AND METHODS

Placenta specimens of 46 patients in early pregnancy were analyzed (normal pregnancy (n = 15), spontaneous (n = 15) and habitual abortion (n = 16)). TLR4 and IL4Rα were analyzed by immunohistochemistry, immunofluorescence and real time PCR. Statistical analysis was carried out using SPSS 23 and Microsoft Excel.

RESULTS

IL4Rα could be detected in trophoblast cells of all groups. It was significantly downregulated in the syncytiotrophoblast of spontaneous and recurrent abortions (p = 0.001), and in decidual tissue of spontaneous abortions (p = 0.001). Expression of TLR4 was decreased in the intermediate villous trophoblast (IVT) and decidua of spontaneous abortions (p = 0.04 & 0.003, respectively). On mRNA level expression of IL4Rα and TLR4 was significantly decreased in the group of recurrent miscarriages (IL4Rα p = 0.002, TLR4 p = 0.004).

CONCLUSION

This study contributes new findings to the understanding of the complex molecular interplay at the fetomaternal interface in normal pregnancy and miscarriages. For the first time signaling via IL4Rα being involved at the very beginning of the generation of new life could demonstrated. Moreover, new evidence was provided regarding TLR4 playing a pivotal role in early pregnancy.

PPARγ Expression Is Diminished in Macrophages of Recurrent Miscarriage Placentas

PPARγ belongs to the group of nuclear receptors which is expressed in the trophoblast and together with other factors is responsible for the maintenance of pregnancy. Apart from that PPARγ is also a main factor for macrophage polarization. The aim of this study was to investigate the combined expression pattern and frequency of PPARγ under physiological circumstances and in spontaneous and recurrent miscarriages in the trophoblast and in maternal macrophages of the decidua. Human placental tissues of the first trimester (15 physiologic pregnancies, 15 spontaneous abortion and 16 recurrent miscarriage placentas) were analyzed for expression of the nuclear receptor PPARγ. Expression changes were evaluated by immunohistochemistry and real time PCR (RT-PCR) in trophoblast and in maternal macrophages of the decidua. Maternal macrophages were identified by double immunofluorescence using cluster of differentiation 68 (CD68) as marker for macrophages and further characterized regarding their M1/M2 polarization status. The intermediate villous trophoblast revealed a significantly lower PPARγ expression in spontaneous and recurrent abortion. Maternal macrophages express PPARγ. Their number is significantly enhanced in the decidua of spontaneous miscarriages whereas in recurrent miscarriages maternal macrophages seem to express PPARγ only in very few cases. PPARγ is associated with an M2 polarization state that is common for decidual macrophages. The lack of PPARγ in recurrent miscarriage decidual macrophages seems to be associated with a specific inflammatory response against the fetus.

Dopamine synthesis and dopamine receptor expression are disturbed in recurrent miscarriages

OBJECTIVES

l-dopa decarboxylase (DDC) is responsible for the synthesis of dopamine. Dopamine, which binds to the D₂-dopamine receptor (D2R), plays an important role in the maintenance of pregnancy. Aim of our study was the analysis of DDC and D2R expression in placentas of spontaneous miscarriages (SMs) and recurrent miscarriages (RMs) in comparison to healthy controls.

METHODS

Patients with SM (n = 15) and RM (n = 15) were compared with patients from healthy pregnancies (n = 15) (pregnancy weeks 7-13 each). Placental tissue has been collected from SMs and RMs from the first trimester (Department of Gynaecology and Obstetrics, LMU Munich) and from abruptions (private practice, Munich). Placental cell lines, BeWo- and JEG-3 cells, were stimulated with the trace amines T₀AM and T₁AM in vitro.

RESULTS

Levels of DDC and D2R in trophoblasts and the decidua were lower in RMs in comparison to healthy controls. Stimulation of BeWo cells with T₁AM significantly reduced DDC mRNA and protein levels. Via double-immunofluorescence, a DDC-positive cell type beneath decidual stromal cells and foetal EVT in the decidua could be detected.

CONCLUSIONS

Downregulation of DDC and D2R in trophoblasts of RMs reflects a reduced signal cascade of catecholamines on the foetal side.

TAAR1 induces a disturbed GSK3β phosphorylation in recurrent miscarriages through the ODC

OBJECTIVES

Thyroid hormones play an important role in the maintenance of pregnancy. Their derivates, endogenous amines, act via binding to the trace amine-associated receptor (TAAR1). The aim of our study was to analyse the regulation of TAAR1, serine/threonine kinase (pGSK3β) and ornithine decarboxylase (ODC) in placentas of healthy pregnancies, spontaneous (SM) and recurrent miscarriages (RM) and to investigate the influence of thyroid hormone derivates on TAAR1 expression in trophoblast model cells in vitro.

METHODS

Patients with SM (n = 15) and RM (n = 15) were compared with patients with healthy pregnancies (n = 15) (pregnancy weeks 7-13 each). Immunohistochemistry was applied to analyse placental TAAR1, pGSK3β and ODC expression. Protein expression of the receptors after stimulation with T₃, T₁AM and RO5203548 in BeWo trophoblast model cells was determined via Western blot. Double-immunofluorescence was used to determine placental expression of TAAR1 and ODC.

RESULTS

Levels of TAAR1, pGSK3β and ODC were higher in placentas of RM in comparison to healthy controls. Stimulation of BeWo cells with T₃, T₁AM and RO5203548 significantly increased TAAR1 expression. ODC expression in BeWo cells was upregulated through T₃. Via double-immunofluorescence, TAAR1 and ODC-positive EVT could be detected.

CONCLUSIONS

Upregulation of placental TAAR1 may indicate an increased decarboxylation of thyroid hormones in miscarriages. Patients with RM may have a lack of T₃ through an enhanced transformation of T₃ into T₁AM induced by the ODC. Future investigations could be carried out to analyse what role a prophylactic T₃ substitution plays for patients.

Prototype and Chimera-Type Galectins in Placentas with Spontaneous and Recurrent Miscarriages

Galectins are galactose binding proteins and, in addition, factors for a wide range of pathologies in pregnancy. We have analyzed the expression of prototype (gal-1, -2, -7, -10) and chimera-type (gal-3) galectins in the placenta in cases of spontaneous abortions (SPA) and recurrent abortions (RA) in the first trimester. Fifteen placental samples from healthy pregnancies were used as a control group. Nine placentas were examined for spontaneous abortions, and 12 placentas for recurrent abortions. For differentiation and evaluation of different cell types of galectin-expression in the decidua, immunofluorescence was used. For all investigated prototype galectins (gal-1, -2, -7, -10) in SPA and RA placenta trophoblast cells the expression is significantly decreased. In the decidua/extravillous trophoblast only gal-2 expression was significantly lowered, which could be connected to its role in angiogenesis. In trophoblasts in first-trimester placentas and in cases of SPA and RA, prototype galectins are altered in the same way. We suspect prototype galectins have a similar function in placental tissue because of their common biochemical structure. Expression of galectin 3 as a chimera type galectin was not found to be significantly altered in abortive placentas.