Recent insights on the genetics and epigenetics of endometriosis.

Endometriosis is a gynecologic disease affecting up to 10% of the women and a major cause of pain and infertility. It is characterized by the implantation of functional endometrial tissue at ectopic positions generally within the peritoneum. This complex disease has an important genetic component with a heritability estimated at around 50%. This review aims at providing recent insights into the genetic bases of endometriosis, and presents a detailed overview of evidence of epigenetic alterations specific to this disease. In the future, these alterations may constitute therapeutic targets for pharmacological compounds able to modify the epigenetic code.

IFPA meeting 2014 workshop report: Animal models to study pregnancy pathologies; new approaches to study human placental exposure to xenobiotics; biomarkers of pregnancy pathologies; placental genetics and epigenetics; the placenta and stillbirth and fetal growth restriction.

Workshops are an important part of the IFPA annual meeting as they allow for discussion of specialized topics. At IFPA meeting 2014 there were six themed workshops, five of which are summarized in this report. These workshops related to various aspects of placental biology but collectively covered areas of animal models, xenobiotics, pathological biomarkers, genetics and epigenetics, and stillbirth and fetal growth restriction.

Endometriosis also affects the decidua in contact with the fetal membranes during pregnancy.

STUDY QUESTION: Are the fetal membranes of women affected with endometriosis similar to those from disease-free women? SUMMARY ANSWER: Decidua of women with endometriosis is able to generate endometriotic-like lesions in contact with the fetal membranes. WHAT IS KNOWN ALREADY: Eutopic endometrium of women affected with endometriosis presents compromised properties. Endometrium undergoes decidualisation to accept and to further control the conceptus development during pregnancy. Decidualized endometrium is in close contact with the chorionic membrane and forms the choriodecidual layer, a major maternal-fetal interface. STUDY DESIGN, SIZE, DURATION: This is a laboratory case-control study involving diseased versus control samples. Eleven case samples and 11 control samples were collected from women in a tertiary care/research center between November 2011 and December 2013. PARTICIPANTS/MATERIALS, SETTING, METHODS: Participants were consecutive pregnant women affected with confirmed endometriosis and disease free women, who underwent Cesarean section before labor for obstetrical indication. The choriodecidual tissues were characterized using histology, immunohistochemistry, transcriptomic and whole genome CpG methylation analyses. MAIN RESULTS AND THE ROLE OF CHANCE: We demonstrate for the first time the presence of endometriotic-like lesions within the decidual side of the choriodecidua of the fetal membranes from women affected with severe endometriosis. Fetal membranes from women affected with endometriosis exhibited glandular components in the choriodecidual layer surrounded by enlarged decidualized cells disseminated along the entire membrane surface. Significant deregulation (variation of expression ≥2, P-value ≤0.05) was observed for 2773 genes known to be enriched in processes involved in glandular function, endocrine and nervous system, neoangiogenesis, and autoimmune disease. CpG methylation analysis revealed 5999 differentially methylated regions with a P-value ≤0.05. LIMITATIONS, REASONS FOR CAUTION: We studied women who delivered at term by Cesarean section before labor, following an uneventful pregnancy. Notwithstanding this, one cannot exclude that the presence of disseminated endometriotic lesions within the choriodecidual layer of the fetal membranes may disturb the anatomical integrity and/or the function of the membranes in some women with endometriosis. WIDER IMPLICATIONS OF THE FINDINGS: Our results shed new light on the capability of the diseased decidua to develop lesions not only at ectopic autologous locations, but also on the semi-allogenous fetal membranes, a particularly immunotolerant environment.

Impaired alveolarization and intra-uterine growth restriction in rats: a postnatal genome-wide analysis.

Intra-uterine growth restriction (IUGR) dramatically increases the risk of bronchopulmonary dysplasia in preterm babies, a disease characterized by arrested alveolarization and abnormal microvascular angiogenesis. We have previously described a rodent low protein diet (LPD) model of IUGR inducing impaired alveolarization, but failed to demonstrate any modification of the classical factors involved in lung development. We performed a genome-wide microarray analysis in 120 rat pups with LPD-induced IUGR and their controls, at three key time points of the alveolarization process: postnatal day 4 (P4): start of alveolarization; P10: peak of the alveolarization process and P21: end of the alveolarization process. Results were analysed using Arraymining, DAVID and KEGG software and validated by qRT-PCR and western blots. Considering a cut-off of 2:1 as significant, 67 transcripts at P4, 102 transcripts at P10 and 451 transcripts at P21 were up-regulated, and 89 transcripts at P4, 25 transcripts at P10 and 585 transcripts at P21 were down-regulated. Automatic functional classification identified three main modified pathways, 'cell adhesion molecules', 'cardiac muscle contraction' and 'peroxisome proliferator-activated receptor' (PPAR). Protein analysis confirmed involvement of the PPAR pathway, with an increase of FABP4, an activator of this pathway, at P4 and an increase of adiponectin at P21. Other data also suggest involvement of the PPAR pathway in impaired alveolarization. Our results show that deregulation of the PPAR pathway may be an important component of the mechanism inducing impaired alveolarization observed in IUGR. The complete dataset is available as GEO profiles on the Gene Expression Omnibus (GEO) database ( www.ncbi.nih.gov/geo/, GEO Accession No. GSE56956).

[Endothelial dysfunction: role in the maternal syndrome of preeclampsia and long-term consequences for the cardiovascular system]. / Dysfonction endothéliale: rôle dans le syndrome maternel de la prééclampsie et conséquences à long terme pour le système cardiovasculaire.

Preeclampsia is a pregnancy disorder being a leading cause of maternal and fetal mortality and morbidity. It is a complex multisystem disease characterized by hypertension and proteinuria. In preeclampsia the placenta releases factors into the maternal circulation which cause a systemic endothelial dysfunction. Here, we review data demonstrating the central role played by the endothelium in the development of the maternal syndrome of preeclampsia. We present also original data showing how circulating factors present in the plasma of preeclamptic women can alter the transcriptome of endothelial cells. The expression of genes involved in essential functions such as vasoregulation, oxidative stress, apoptosis and cell proliferation show differential expression when endothelial cells are exposed to preeclamptic or normal pregnancy plasma. We conclude by discussing the growing evidences that the alterations of the endothelium during preeclampsia are linked to an increased risk of cardiovascular diseases latter on life. Therefore, a better understanding of the modifications undergone by the endothelial cells during preeclampsia is essential to develop new therapeutic approaches to both, manage preeclampsia and to prevent the long-term sequelae of the disease on women cardiovascular system.

[Endometriosis-associated ovarian cancers: pathogenesis and consequences on daily practice]. / Les cancers de l'ovaire associés à l'endométriose : physiopathologie et conséquences sur la pratique clinique.

Endometriosis is considered as a tumor-like lesion under the World Health Organization (WHO) classification of ovarian tumors. Data from large cohort and case-control studies indicate that patients with a history of endometriosis have an increased risk of ovarian cancer. Recent findings suggest an association between endometriosis and the entire type 1 ovarian tumors group including clear-cell, endometrioid and low-grade serous carcinomas. However, current evidence is lacking to draw definitive conclusion whether this association represents causality or the sharing of common risk factors. Nevertheless, assumption that endometriosis could be a precursor of malignancy raises many issues about serial screening, surgical management and surveillance of endometriosis. Beyond these concerns, endometriosis-associated ovarian cancers seem to be a genuine clinical entity as regards clinicopathological features. In view of the high incidence of endometriosis (10 % of women of childbearing age), the low incidence of endometriosis-associated ovarian cancers and the psychological consequences for those women, systematic screening and surgical exploration seem very questionable in this context.

EG-VEGF controls placental growth and survival in normal and pathological pregnancies: case of fetal growth restriction (FGR).

Identifiable causes of fetal growth restriction (FGR) account for 30 % of cases, but the remainders are idiopathic and are frequently associated with placental dysfunction. We have shown that the angiogenic factor endocrine gland-derived VEGF (EG-VEGF) and its receptors, prokineticin receptor 1 (PROKR1) and 2, (1) are abundantly expressed in human placenta, (2) are up-regulated by hypoxia, (3) control trophoblast invasion, and that EG-VEGF circulating levels are the highest during the first trimester of pregnancy, the period of important placental growth. These findings suggest that EG-VEGF/PROKR1 and 2 might be involved in normal and FGR placental development. To test this hypothesis, we used placental explants, primary trophoblast cultures, and placental and serum samples collected from FGR and age-matched control women. Our results show that (1) EG-VEGF increases trophoblast proliferation ([(3)H]-thymidine incorporation and Ki67-staining) via the homeobox-gene, HLX (2) the proliferative effect involves PROKR1 but not PROKR2, (3) EG-VEGF does not affect syncytium formation (measurement of syncytin 1 and 2 and ß hCG production) (4) EG-VEGF increases the vascularization of the placental villi and insures their survival, (5) EG-VEGF, PROKR1, and PROKR2 mRNA and protein levels are significantly elevated in FGR placentas, and (6) EG-VEGF circulating levels are significantly higher in FGR patients. Altogether, our results identify EG-VEGF as a new placental growth factor acting during the first trimester of pregnancy, established its mechanism of action, and provide evidence for its deregulation in FGR. We propose that EG-VEGF/PROKR1 and 2 increases occur in FGR as a compensatory mechanism to insure proper pregnancy progress.

Placental expression of the obesity-associated gene FTO is reduced by fetal growth restriction but not by macrosomia in rats and humans.

Genetic variants in the FTO (fat mass- and obesity-associated) gene have the highest association of all obesity-associated genes. Its placental expression was shown to relate to birth weight, suggesting that it may participate in the control of fetal weight gain. To gain more insight into the implication of FTO in fetal growth, we measured its placental expression in samples including extremes of abnormal fetal growth, such as after intrauterine growth restriction (IUGR) or macrosomia in both rats and humans. In rats, fetal growth was modulated by maternal nutritional modifications. In humans, placental villi were collected from pathological pregnancies (i.e. with IUGR or fetal macrosomia). Placental FTO mRNA expression was reduced by IUGR but was not significantly affected by macrosomia in either rats or humans. Our data suggest that placental FTO may participate in interactions between the in utero environment and the control of fetal growth under IUGR conditions by modulating epigenetic processes.

[Comparative analysis of mice models for preeclampsia]. / Analyse comparative des modèles souris de prééclampsie.

Preeclampsia is a multifactorial disease of pregnancy. It is a major cause of maternal and perinatal mortality and morbidity and is defined by the de novo onset of hypertension and proteinuria after the 20th week of pregnancy. This pathology manifests during the early stages of pregnancy, making it hard to predict and very difficult to study in humans (presymptomatic phase and lack of tissues access). Animal models are therefore necessary to study the physiopathology of preeclampsia, however, since this pathology is specifically human, there are no spontaneous models. Animal models have thus been engineered. In this review, the models obtained in mice are described and compared. These models are essential for the development of new therapeutic strategies.

Placental BDNF/TrkB signaling system is modulated by fetal growth disturbances in rat and human.

The brain-derived neurotrophic factor (BDNF) has been shown to exert an important role during implantation, placental development, and fetal growth control in mice. Its expression is closely related to the nutritional status in several tissues such as in the nervous system. In a previous study, we demonstrated that maternal undernutrition (MU), during the perinatal life, modified both the BDNF and its functional receptor, the tyrosine kinase receptor B (TrkB) gene expression in the brain of growth-restricted rat offspring during sensitive developmental windows, suggesting that these early modifications may have long-lasting consequences. In the present study, we measured BDNF/TrkB mRNA and protein levels in rat placentas from mothers submitted to a 50% food restriction during gestation, and in human placentas from pregnancies with fetal growth restriction or fetal macrosomia. In the rat, two subtypes of placental TrkB receptors have been identified: the TrkB-FL and TrkB-T1 receptors. We found that MU induced intrauterine growth restriction (IUGR) of fetuses at term and decreased the placental BDNF mRNA and protein levels. Placentae from undernourished mothers exhibited an increased mRNA expression of TrkB-FL whereas both TrkB-FL and TrkB-T1 receptors proteins levels were not modified. In human IUGR placentas, both BDNF and TrkB receptor mRNA expressions were up-regulated. Finally, although neither BDNF nor TrkB mRNA levels were altered by fetal macrosomia alone, BDNF mRNA levels were decreased when macrosomia was associated with maternal type 1 diabetes. These results show that the placental BDNF/TrkB system is modulated in rats and humans during pregnancies with fetal growth perturbations and is affected by the maternal energetic status. These data suggest that this system may exert an important role for the feto-placental unit development and that it may also be implicated in the etiology of pathologies related to placental and fetal growth disturbances.

[Neurotrophins and pain in endometriosis]. / Neurotrophines et douleur: étude d'expression et de corrélation dans l'endométriose.

OBJECTIVES: To evaluate the expression of five members of the neurotrophins family in ovarian endometriotic cyst (endometrioma) (OMA), compared to eutopic endometrium (EE) and to examine the correlation between the levels of induction and the pain intensity. PATIENTS AND METHODS: Twelve Caucasian women in luteal phase, operated for painful stage IV endometriosis were assigned to 2 groups according to a total Visual Analog Scale (tVAS) score above 15 or below 10. tVAS takes into account all VAS scores for dysmenorrhea, deep dyspareunia, non cyclic chronic pelvic pain, gastrointestinal and lower urinary symptoms. Samples of OMA and EE were processed by quantitative reverse transcriptase-polymerase chain reaction (RT-PCR) for NGF, BDNF, NT-3, NT-4/5 and NTRK2 mRNA expression. Expression levels in OMA were compared to those in EE on one hand and between two groups of 6 mild painful and 6 highly painful patients on the other. RESULTS: All neurotrophins were significantly higher expressed in OMA than in EE, in particular NGF and BDNF (induction ratios: 20.6 and 9.7, respectively). In contrast, no correlation was observed between induction ratios and pain intensity. CONCLUSION AND DISCUSSION: This is the first study reporting an over-expression of all neurotrophins in endometriosis, as only NGF was previously documented. It confirms the central role of this family in the genesis and modulation of pain in endometriosis. Anti-neurotrophin selective therapy might be a promising way of analgesia in the future.

[Endometriosis and genetics: what responsibility for the genes?]. / Endométriose et génétique : les gènes sont-ils responsables de la maladie ?

Endometriosis is a very frequent and debilitating disease responsible for a considerable socio-economic toll. In spite of that, its pathogenesis remains enigmatic. Endometriosis is hold for a multifactorial pathology resulting from the mixed effects of environmental and genetic factors. To date, few susceptibility factors have been reported, with the exception of some polymorphisms in estrogen and progesterone receptors. Large-scale expressional studies have clearly demonstrated that endometriosis is a hormone-dependant disease, characterized by three main features: (i) inflammation, (ii) excessive production of estrogens, and (iii) progesterone resistance. Endometriosis is also considered as a benign metastatic disease, closely linked to cancer. However, the risk of malignant transformation appears to be very limited, likely by a systematic repression of the genes involved in cell cycle and a specific regulation of the HOX genes. Lastly, endometriosis might result from abnormalities of the eutopic endometrium, which show the same molecular alterations than the ectopic endometrium, to a lesser extent however. These alterations, possibly occurring during the embryonic life through epigenetic and genetic predisposition, could lead to an earlier and non-invasive diagnosis for endometriosis.

Cullins in human intra-uterine growth restriction: expressional and epigenetic alterations.

Intra-uterine growth restriction (IUGR) is defined by a restriction of fetal growth during gestation. It is a prevalent significant public health problem that jeopardizes neonatal health but also that can have deleterious consequences later in adult life. Cullins constitute a family of seven proteins involved in cell scaffold and in selective proteolysis via the ubiquitin-proteasome system. Most Cullins are critical for early embryonic development and mutations in some Cullin genes have been identified in human syndromes including growth retardation. Our work hypothesis is that Cullins, particularly CUL4B and CUL7, are involved in placental diseases and especially in IUGR. Thus, expression of Cullins and their cofactors was analyzed in normal and pathological placentas. We show that they present a constant significant over-expression in IUGR placentas, whose extent is dependent on the position of the interrogated fragment along the cDNAs, suggesting the existence of different isoforms of the genes. Particularly, the CUL7 gene is up-regulated up to 10 times in IUGR and 15 times in preeclampsia associated with IUGR. The expression of cofactors of Cullins participating to functional complexes has also been evaluated and showed a similar significant increase in IUGR. Promoters of Cullin genes appeared to be under the control of the SP1 transcription factor. Finally, methylation levels of the CUL7 promoter in placental tissues are modulated according to the pathological conditions, with a significant hypomethylation in IUGR. These results concur to pinpoint the Cullin family as a new set of markers of IUGR.

[Current debates on immunology of preeclampsia. Report of the sixth international workshop of Reunion Island (Indian Ocean, December 2008)]. / Débats actuels sur l'immunologie de la prééclampsie. Comptes rendus du sixième colloque international de La Réunion (décembre 2008).

Hypertensive disorders of pregnancy (HDP) represent globally 10% of human births and their major complication, preeclampsia, 3 to 5%. The etiology of these HDP remains still uncertain, however major advances have been made these last 25 years. The Sixth International Workshop on Reproductive Immunology, Immunological Tolerance and Immunology of Preeclampsia 2008 celebrated its 10th Anniversary in Reunion-island (French overseas Department in the Indian Ocean). Over this decade, these six workshops have contributed extensively to immunological, epidemiological, anthropological and even vascular debates. The defect of trophoblastic invasion encountered in preeclampsia, intra-uterine growth retardation and to some extend also preterm labour has been understood only at the end of the 1970's. On the other hand, clinical and epidemiological findings at the end of the 20th century permitted to apprehend that "preeclampsia disease of primiparae" may in fact well be the disease of first pregnancies at the level of human couples. Among the important advances, immunology of reproduction is certainly the topic where knowledge has literally exploded in the last decade. This paper relates some major steps in comprehension of this disease and focuses on the interest to follow these immunological works and their new concepts. It seems, at the beginning of the 21st century, that we are possibly closer than ever to understand the etiology of this obstetrical enigma. In this quest, the immunology of reproduction will certainly come out as one of the main players.

Mouse models for identifying genes modulating fertility parameters.

Fertility can be defined as the natural capability of giving life. It is an important factor both for human medicine, where ~10% of the couples call for the services of assisted reproductive technologies, and for species of economic interest. In particular, in dairy cows, the recent years have seen a kind of competition between milk production and fertility, and genes improving fertility are now considered as parameters to be selected for. The study of fertility pathways is nevertheless made difficult by the strong impact of environmental factors on this parameter, as well as by the number of genes potentially involved (as shown by systematic transcriptome analysis studies in the recent years). One additional level of complexity is given by the fact that factors modulating fertility will probably be sex specific. The usage of mouse models has been one of the solutions exploited for tackling with these difficulties. Here, we review three different approaches using mice for identifying genes modulating fertility in mammals: gene invalidation, positional cloning and in vitro mutagenesis. These three approaches exploit specific characteristics of the mouse, such as the possibility of controlling precisely the environment, an excellent genetic characterization and the existence of genomic and molecular tools equalled only in humans. Many indications suggest that at least some of the results obtained in mice could be easily transposed to the species of interest.

Identification of new quantitative trait Loci (other than the PRNP gene) modulating the scrapie incubation period in sheep.

Although susceptibility to scrapie is largely controlled by the PRNP gene, we have searched for additional genomic regions that affect scrapie incubation time in sheep, using two half-sib families with a susceptible PRNP genotype and naturally infected by scrapie. Quantitative trait loci were detected on OAR6 and OAR18.

Genetic and epigenetic factors contribute to the onset of preeclampsia.

Preeclampsia (PE) is a major cause of perinatal materno-foetal morbidity and pregnancy-associated-mortality in industrialized countries. Clinically, PE associates maternal pregnancy-induced hypertension with proteinuria. PE is often considered as a two-stage disease. The first stage is a shallow cytotrophoblastic invasion which induces cycles of hypoxia-reoxygenation at the placental level. Subsequently an abnormal expression pattern occurs and is followed by the release of soluble factors and trophoblastic debris in the maternal blood flow. These stimuli trigger the second phase of the disease, the maternal syndrome. Although some molecular actors have been recently identified, mechanisms of the disease onset remains poorly understood. It seems that combinations of genetic, epigenetic and environmental factors are involved. Here, we suggest that epigenetic marks have to be considered to decipher the physiopathological process of PE. Since these marks must be established early and are traceable in the maternal blood flow, they could constitute a diagnosis tool.

A hierarchical analysis of transcriptome alterations in intrauterine growth restriction (IUGR) reveals common pathophysiological pathways in mammals.

Intra-uterine growth restriction (IUGR) is a frequent disease, affecting up to 10% of human pregnancies and responsible for increased perinatal morbidity and mortality. Moreover, low birth weight is an important cause of the metabolic syndrome in the adult. Protein depletion during the gestation of rat females has been widely used as a model for human IUGR. By transcriptome analysis of control and protein-deprived rat placentas, we were able to identify 2543 transcripts modified more than 2.5 fold (1347 induced and 1196 repressed). Automatic functional classification enabled us to identify clusters of induced genes affecting chromosome structure, transcription, intracellular transport, protein modifications and apoptosis. In particular, we suggest the existence of a complex balance regulating apoptosis. Among repressed genes, we noted several groups of genes involved in immunity, signalling and degradation of noxious chemicals. These observations suggest that IUGR placentas have a decreased resistance to external aggression. The promoters of the most induced and most repressed genes were contrasted for their composition in putative transcription factor binding sites. There was an over-representation of Zn finger (ZNF) proteins and Pdx1 (pancreatic and duodenal homeobox protein 1) putative binding sites. Consistently, Pdx1 and a high proportion of ZNF genes were induced at the transcriptional level. A similar analysis of ZNF promoters showed an increased presence of putative binding sites for the Tata box binding protein (Tbp). Consistently again, we showed that the Tbp and TBP-associated factors (Tafs) were up-regulated in IUGR placentas. Also, samples of human IUGR and control placentas showed that human orthologous ZNFs and PDX1 were transcriptionally induced, especially in non-vascular IUGR. Immunohistochemistry revealed increased expression of PDX1 in IUGR human placentas. In conclusion, our approach permitted the proposition of hypotheses on a hierarchy of gene inductions/repressions leading to massive transcriptional alterations in the IUGR placenta, in humans and in rodents.

A 12 000-rad whole-genome radiation hybrid panel in sheep: application to the study of the ovine chromosome 18 region containing a QTL for scrapie susceptibility.

Whole-genome radiation hybrid (RH) panels have been constructed for several species, including cattle. RH panels have proven to be an extremely powerful tool to construct high-density maps, which is an essential step in the identification of genes controlling important traits, and they can be used to establish high-resolution comparative maps. Although bovine RH panels can be used with ovine markers to construct sheep RH maps based on bovine genome organization, only some (c. 50%) of the markers available in sheep can be successfully mapped in the bovine genome. So, with the development of genomics and genome sequencing projects, there is a need for a high-resolution RH panel in sheep to map ovine markers. Consequently, we have constructed a 12 000-rad ovine whole-genome RH panel. Two hundred and eight hybrid clones were produced, of which 90 were selected based on their retention frequency. The final panel had an average marker retention frequency of 31.8%. The resolution of this 12 000-rad panel (SheepRH) was estimated by constructing an RH framework map for a 23-Mb region of sheep chromosome 18 (OAR18) that contains a QTL for scrapie susceptibility.

Expression and localization of alpha-fetoprotein mRNA and protein in human early villous trophoblasts.

Alpha-fetoprotein (AFP) is a major plasma protein produced during human fetal life. It is a good marker for several possible disorders affecting gestation. We previously reported that afp gene expression, which takes place mainly in yolk sac and fetal liver, also occurs in normal human placenta, specifically in early pregnancy. The aim of the present study was to determine the precise location of AFP synthesis sites within the placental villi. In situ hybridization and immunohistochemical experiments were performed on sections obtained from placentas of first-trimester and full-term pregnancies. We found that the pattern of afp gene expression was restricted to specific villous trophoblastic areas in early placentas. Both afp transcripts and AFP protein were mainly located in discontinuous regions, at junctions between two villi and at budding sites. In contrast, no AFP expression was detected in the cytotrophoblastic extravillous proliferative zone or in other placental cell types. According to the earlier studies, no AFP synthesis was detected in placental villous tissue from full-term pregnancies, using in situ hybridization and immunohistochemistry.