Regulation of TNF-alpha mRNA expression in endometrial cells by TNF-alpha and by oestrogen withdrawal

During each menstrual cycle, the human endometrium undergoes a series of orchestrated and well controlled changes in anticipation of the arrival of the blastocyst. In the absence of implantation, the endometrium is shed. The underlying basis of the menstrual bleeding is not clear, however, it seems to be related to steroid hormone withdrawal. We showed that tumour necrosis factor-alpha (TNF-alpha) is released by human endometrium and that endometrial epithelial cells are a major source of TNF-alpha mRNA and protein. We show here that TNF-alpha mRNA shows a specific menstrual cycle-dependent expression. The expression of TNF-alpha is mostly minimal throughout the proliferative, early and mid-secretory phases. Expression of TNF-alpha mRNA, however, is increased in the human endometrium in the late secretory phase and during endometrial bleeding. Such a menstrual cycle-dependent expression suggests that specific signals regulate the expression of TNF-alpha mRNA in the human endometrium. In vitro, the expression of TNF-alpha mRNA in endometrial epithelial cells could be regulated by exogenous TNF-alpha. This induced expression was both time- and dose-dependent. In vitro, the TNF-alpha mRNA expression was not altered by oestrogen, progesterone, or both, in the endometrial epithelial cells under conditions that maintain the steroid hormone receptors. However, in vivo, oestrogen withdrawal led to an enhanced expression of TNF-alpha in endometrial epithelial cells. These findings suggest that the up-regulation of TNF-alpha in human endometrium in the late secretory phase may be related to the falling serum oestrogen concentration at the end of the menstrual cycle as well as the potentiating effect of released TNF-alpha on its own mRNA expression.     

Steroid receptor coactivator AIB1 in endometrial carcinoma, hyperplasia and normal endometrium: Correlation with clinicopathologic parameters and biomarkers.

Members of the p160 steroid receptor cofactor family, including AIB1 (Amplified in Breast Cancer 1) (also known as SRC-3/RAC3/ACTR/pCIP/TRAM-1), are of interest in endometrial carcinoma as they affect the function of estrogen (ER) and progesterone receptors (PR). Since it is feasible that alterations in the expression levels of coregulators can either augment ER activity or reduce the ability of PR to oppose ER action in endometrial cancers, our primary aim was to analyze expression of the AIB1 protein in endometrial carcinoma, carcinoma-associated complex atypical hyperplasia, and carcinoma-associated normal endometrium using immunohistochemistry and tissue microarrays. Expression of AIB1 was compared with other biomarkers and clinicopathologic parameters. We also tested AIB1 expression in non-carcinoma associated hyperplastic, normal secretory and proliferative endometrium to determine baseline AIB1 levels. In endometrial carcinoma, there is a higher expression of AIB1 compared to carcinoma-associated complex atypical hyperplasia (0.007) or carcinoma-associated normal endometrium (<0.001). AIB1 expression correlates with older age (P = 0.003), peri- or postmenopausal status (P = 0.002) and a higher grade of carcinomas (P = 0.04). There were no differences in the expression of additional steroid hormone receptor co-activators (SRC-1 and p300/CBP) and the co-repressor SMRT between histologic categories. AIB1 expression correlated with ER (r = 0.30, P = 0.006). The strongest correlation was between ER and PR-B isoform nuclear expression (r = 0.52, P < 0.0001). AIB1 levels were higher in non-carcinoma associated normal and hyperplastic endometrium compared to carcinoma-associated complex atypical hyperplasia and carcinoma-associated normal endometrium, and were the highest in normal secretory endometrium. In conclusion, high AIB1 expression in endometrial carcinoma is associated with parameters of poor prognosis. We propose that when AIB1 is overexpressed in endometrial carcinoma, ER action is augmented, leading to endometrial hyperplasia and progression to malignancy. Future studies correlating expression with response to hormonal therapy may be beneficial.     

Endothelin synthesis and receptors in human endometrium throughout the normal menstrual cycle

This study was undertaken to investigate the presence of messengerRNA (mRNA) for prepro-endothelin-l (ET-1) and the known receptorsubtypes (ET_A and ET_B) in human endometrium at different stagesof the menstrual cycle obtained at hysterectomy. Northern blotanalysis revealed expression of ET-1 mRNA in human endometriumduring the normal menstrual cycle. The concentration of ET-1mRNA in endometrial tissue was greater during the menstrualand proliferative phases than during the ovulatory and secretoryphases. Immunoreactive ET-1 was secreted into the medium ofisolated endometrial stromal cells. Oestradiol and progesteronesignificantly attenuated ET-1 release in endometrial stromalcells cultured for 6 days. ET_A and ET_B mRNA were also presentin endometrial tissue of the normal cycle. The concentrationof ET_A receptor mRNA was greater in the proliferative phasethan in the secretory phase, whereas expression of ET_B mRNAincreased in menstrual phase. ET-1 significantly increased extracellularaccumulation of cyclic AMP (cAMP), intracellular generationof inositol phosphates and significantly enhanced DNA synthesisin cultured endometrial stromal cells from the proliferativephase. Our results showed that human endometrial cells synthesizedand released ET-1, and contained ET_A and ET_B receptors whichwere functionally coupled to phosphoinosttide breakdown andto adenylate cyclase with the increase of cAMP by ET-1 stimulation.Our findings suggest that ET-1 may have a potential autocrineand/or paracrine function in human endometrial stromal cells. cyclic AMP/endothelin-l synthesis/human endometrium/inositol phosphate/receptors     

Gene expression pattern and immunoreactive protein localization of LGR7 receptor in human endometrium throughout the menstrual cycle

Relaxin (RLX) is a pregnancy-associated polypeptide hormone. In non-pregnant women, the peak of circulating relaxin coincides with the window of endometrial receptivity and both in vivo and in vitro experiments showed that it plays a role in the decidualization process. Recently, two receptors, LGR7 and LGR8, have been identified as high affinity receptors for relaxin. Here we describe LGR7 mRNA and protein expression in human endometrium using semi-quantitative and quantitative fluorescent PCR (Q-PCR) and immunohistochemical analyses. Three different experimental designs were used. First, endometrial biopsies from five different phases of the menstrual cycle were analysed. Secondly, we assessed the early luteal phase in more detail. Finally we analysed the expression at LH+2 (2 days after the natural LH surge, pre-receptive endometrium) versus LH+7 (receptive endometrium) within the same menstrual cycle from the same patient to avoid inter-cycle or inter-person variations in gene expression. Our results indicate that there is no consistent regulation of LGR7 mRNA expression, neither during the menstrual cycle nor during the early-mid-luteal phase. In general, we observed a large degree of variation in LGR7 mRNA expression levels between patients. LGR7 immunoreactive protein was identified in all stages of the menstrual cycle. LGR7 protein was localized in both the epithelial and the stromal compartments, except for the mid-luteal phase when the expression was restricted to the endometrial epithelium. We conclude that no consistent regulation of LGR7 mRNA expression can be detected in human endometrium during the menstrual cycle.     

Phenotypic and functional studies of leukocytes in human endometrium and endometriosis

The aetiology of endometriosis, a common and disabling disorder, is presently unknown, although immune dysfunction could allow ectopic endometrial fragments to survive outside the uterine cavity. These studies investigate the relationship between leukocyte populations, steroid hormone receptor expression, proliferative activity, bcl-2 expression and apoptosis in eutopic and ectopic endometrium from women with endometriosis or adenomyosis at different phases of the menstrual cycle. Significantly increased oestrogen receptor expression, bcl-2 expression and numbers of CD8+ leukocytes were found in ectopic compared with eutopic endometrium in endometriosis, and CD56+ endometrial granulated lymphocytes (eGLs) were significantly reduced in ectopic endometrium. Apoptotic cells were rarely found in control and subject endometria. In contrast with endometriosis, adenomyotic lesions showed identical steroid hormone receptor expression, proliferative activity, bcl-2 expression and leukocyte subpopulations to eutopic endometrium, indicating different aetiologies for these disorders. The unusual CD56+ CD16- eGLs present in large numbers in late secretory phase eutopic endometrium were highly purified (>98%) by immunomagnetic separation. Except for a negligible cytotoxic activity of eGLs from early proliferative samples, cytotoxic activity of eGLs from non-pregnant endometrium during the menstrual cycle was comparable with those in peripheral blood, predominantly CD56+ CD16+ natural killer cells. eGLs from non-pregnant endometrium and early pregnancy showed a variable proliferative response to 5 and 100 U/ml interleukin-2 over 48-h and 120-h time courses. eGLs are evidently functionally important in the eutopic endometrium. Their absence in endometriotic lesions together with increased CD+8 T-cell numbers and increased oestrogen receptor and bcl-2 expression may have significant effects on the development and progression of endometriosis.     

Endothelin synthesis and receptors in human endometrium throughout the normal menstrual cycle

This study was undertaken to investigate the presence of messengerRNA (mRNA) for prepro-endothelin-I (ET-1) and the known receptorsubtypes (ETA and ETB) in human endometrium at different stagesof the menstrual cycle obtained at hysterectomy. Northern blotanalysis revealed expression of ET-1 mRNA in human endometriumduring the normal menstrual cycle. The concentration of ET-1mRNA in endometrial tissue was greater during the menstrualand proliferative phases than during the ovulatory and secretoryphases. Immunoreactive ET-1 was secreted into the medium ofisolated endometrial stromal cells. Oestradiol and progesteronesignificantly attenuated ET-1 release in endometrial stromalcells cultured for 6 days. ETA and ETB mRNA were also presentin endometrial tissue of the normal cycle. The concentrationof ETA receptor mRNA was greater in the proliferative phasethan in the secretory phase, whereas expression of ETB mRNAincreased in menstrual phase. ET-1 significantly increased extracellularaccumulation of cyclic AMP (cAMP), intracellular generationof inositol phosphates and significantly enhanced DNA synthesisin cultured endometrial stromal cells from the proliferativephase. Our results showed that human endometrial cells synthesizedand released ET-1, and contained ETA and ETB receptors whichwere functionally coupled to phosphoinositide breakdown andto adenylate cyclase with the increase of cAMP by ET-1 stimulation.Our findings suggest that ET-1 may have a potential autocrineand/or paracrine function in human endometrial stromal cells.     

Variant progesterone receptor mRNAs are co-expressed with the wild-type progesterone receptor mRNA in human endometrium during all phases of the menstrual cycle

Progesterone receptor (PR) variant mRNAs in human endometrium could encode proteins with the potential to alter progesterone action in states of normal and abnormal endometrial development. We have assessed the expression levels of mRNA for the wild-type PR and splice variants of PR mRNA lacking exon 4 (del-4 PR), exon 6 (del-6 PR), exons 4 and 6 (del-4&6 PR), and part of exon 4 (del-p4 PR) or part of exon 6 (del-p6 PR) in the human endometrium throughout menstrual cycle development. Eighty-eight endometrial specimens (47 proliferative, 41 secretory) were collected from patients undergoing hysterectomy for benign gynaecologic causes. Measurements by RT-PCR indicated that mRNAs for wild-type PR, and splice variants del-4 PR, del-6 PR, del-4&6 PR, del-p6 PR, and a novel del-p4 PR were detected in all endometrial specimens throughout the menstrual cycle. Higher levels of wild-type PR and all PR variant mRNAs were found in the early and mid-proliferative endometrial phases than in secretory endometrium. The relative expression of mRNA for all PR variants compared to wild-type PR mRNA, however, did not change through all stages of endometrial development. We, therefore, found no evidence of differential co-expression of the PR variants compared with wild-type PR during normal menstrual development. Future studies will determine if the expression profile of PR variant mRNAs will be different in the endometrium of patients with infertility, recurrent pregnancy loss, or endometrial adenocarcinoma.     

Lefty is expressed in mouse endometrium in estrous cycle and peri-implantation period

BACKGROUND: Reproductive tissues are unique structures that exhibit cyclic stromal remodelling during menstrual cycles in humans. Ebaf/lefty participates in tissue remodelling of human endometrium by induction of matrix metalloproteases (MMP). METHODS: We describe the temporal expression and spatial distribution of lefty and tissue remodelling events in mouse endometrium. RT-PCR and real-time PCR were used to identify mRNA expression and western blots to analyse Lefty protein. Immunolocalization was performed with specific antibodies and horseradish peroxidase staining. RESULTS: Lefty was expressed in endometrium throughout the estrous cycle. Expression of MMP (MMP-2, -3, -7 and -14) was higher at estrus, metestrus and/or diestrus while collagen content of endometrium decreased in these phases. During pregnancy, lefty levels were higher on days 3-5 and were minimal by day 9. Similarly, expression of endometrial MMP was higher on days 3 and 5 of pregnancy and was low on day 9. During pregnancy, loss of collagen was initiated on day 3, persisted to day 5, and led to a significantly reduced collagen on day 9. Immunoreactive lefty decorated basal laminae, and was associated with extracellular matrix in stroma. CONCLUSIONS: Regulated expression and spatial distribution of lefty in mouse endometrium confines its biological impact on tissues that undergo remodelling during estrous cycle and pregnancy.     

Vascular repair after menstruation involves regulation of vascular endothelial growth factor-receptor phosphorylation by sFLT-1

Regeneration of the endometrium after menstruation requires a rapid and highly organized vascular response. Potential regulators of this process include members of the vascular endothelial growth factor (VEGF) family of proteins and their receptors. Although VEGF expression has been detected in the endometrium, the relationship between VEGF production, receptor activation, and endothelial cell proliferation during the endometrial cycle is poorly understood. To better ascertain the relevance of VEGF family members during postmenstrual repair, we have evaluated ligands, receptors, and activity by receptor phosphorylation in human endometrium throughout the menstrual cycle. We found that VEGF is significantly increased at the onset of menstruation, a result of the additive effects of hypoxia, transforming growth factor-alpha, and interleukin-1beta. Both VEGF receptors, FLT-1 and KDR, followed a similar pattern. However, functional activity of KDR, as determined by phosphorylation studies, revealed activation in the late menstrual and early proliferative phases. The degree of KDR phosphorylation was inversely correlated with the presence of sFLT-1. Endothelial cell proliferation analysis in endometrium showed a peak during the late menstrual and early proliferative phases in concert with the presence of VEGF, VEGF receptor phosphorylation, and decrease of sFLT-1. Together, these results suggest that VEGF receptor activation and the subsequent modulation of sFLT-1 in the late menstrual phase likely contributes to the onset of angiogenesis and endothelial repair in the human endometrium.     

Endometrial leucocytes: expression of steroid hormone receptors.

BACKGROUND: Stromal leucocyte populations in human endometrium comprise T cells, macrophages, and phenotypically unusual endometrial granulated lymphocytes. Their proportions vary during the menstrual cycle and, in particular, endometrial granulated lymphocytes increase in number in the late secretory phase. The stimulus responsible for these cyclical changes is unknown but it is likely that the steroid hormones oestrogen and progesterone play a role. AIMS: To define further the expression of steroid hormone receptors by leucocytes in non-pregnant and pregnant human endometrium. METHODS: Frozen and paraffin wax embedded sections of endometrium from non-pregnant women and early pregnancy decidua were labelled using single and double immunohistochemical techniques with monoclonal antibodies directed against oestrogen and progesterone receptors and various leucocyte subpopulations. RESULTS: Despite the prominence of CD56 positive endometrial granulated lymphocytes in late secretory phase endometrium and early pregnancy decidua, double immunohistochemical labelling showed no evidence of expression of either progesterone or oestrogen receptors by these cells or other endometrial leucocyte populations. CONCLUSIONS: Rather than acting directly, steroid hormones are likely to influence endometrial leucocyte populations indirectly via products of endometrial stromal or epithelial cells that express steroid hormone receptors.     

Progressive rise in the expression of interleukin-6 in human endometrium during menstrual cycle is initiated during the implantation window

In order to be prepared for implantation, human endometriumundergoes a predictable series of proliferative and secretorychanges. Cytokines play an important role in regulation of thesechanges. Therefore, in this study, we immunolocalized the cytokine,interleukin-6 (IL-6), its receptor and the signal transducergp130 in human endometrium throughout the menstrual cycle. Duringthe entire menstrual cycle, the IL-6 receptor and gp130 werefound primarily in the endometrial glands and to a lesser extentin the stroma. The immunoreactivity of these proteins did notchange in endometrial cells during the entire menstrual cyclewith an exception of reduced immunoreactivity of gp130 in endometrialglands during menstrual phase. Immunostaining showed that immunoreactiveIL-6 was weakly expressed in human endometrium during the proliferativephase. Strong immunoreactivity for IL-6 appeared in endometriumduring the putative 'implantation window'. Expression was byfar most pronounced both in the glandular and surface epithelialcells. The amount of immunoreactive IL-6 in the epithelium progressivelyincreased during the secretory/menstrual phases. During thelate secretory phase, only stromal cells in the upper functionalisexhibited immunoreactivity for IL-6. Western blot analysis corroboratedthe immunohistochemical data. Human endometrial IL-6 consistedof a protein with an apparent mobility of 26 kDa. The immunoreactiveband of IL-6 was weak in the proliferative phase. The expressionof this protein increased progressively during the secretory/menstrualphases. The findings show a cell-specific pattern of distributionfor immunoreactive IL-6 in human endometrium. The menstrualcycle-dependent expression of IL-6 suggests that this cytokinemay play a role in changes in endometrium that prepare thistissue for implantation and menstrual shedding. cytokine/endometrium/implantation/interleukin/interleukin-6     

Contraception: Expression of progesterone receptor mRNA in the endometrium during the normal menstrual cycle and in Norplant(R) users

The expression of endometrial progesterone receptor mRNA duringthe human menstrual cycle and in Norplant users was studiedusing digoxigenin-labelled ribonucleic probes for in-situ hybridizationon 6 µm paraffin embedded endometrial sections. The stainingintensity was scored blind semi-quantitatlvely. Blood ovariansteroid concentrations were measured in Norplant users. Alldata were analysed by analysis of variance. Glandular progesteronereceptor mRNA concentrations were low during the menstrual-to-earlyproliferative stage but increased during the early-to-mid tolate-proliferative stage then declined non-significantly overthe secretory stage. No such variation was observed in stromalcells. Progesterone receptor mRNA concentrations were lowerin Norplant than controls during early-to-mid to late-proliferativestages (in glandular epithelium and stroma) and during secretorystage (in stroma only). Norplant subjects with amenorrhoea hadhigher concentrations of stromal progesterone receptor mRNAbut lower plasma oestrogen concentrations than subjects withbreakthrough bleeding. The pattern of variation in progesteronereceptor mRNA concentrations during the normal menstrual cycleresembles the published pattern for the receptor protein. Theresults demonstrate: (i) a differential sensitivity of glandularand stromal progesterone receptors to steroid regulation; (ii)in contrast to previous findings of an increase in immunoreactiveprogesterone receptor protein in Norplant endometrium, progesteronereceptor mRNA concentrations in these tissues were reduced;and (iii) there was significantly more progesterone receptormRNA in subjects with amenorrhoea than in those with breakthroughbleeding.     

Exclusion of non-synonymous SNPs and a polyglutamine tract in SMRT/N-CoR2 as common deleterious mutation for bipolar disorder in the Sagnenay-Lac-St-Jean population.

Bipolar disorder (BP) is a psychiatric illness with both genetic and environmental components occurring with a prevalence of slightly more than 1%. Our previous linkage and case/control studies have pointed to a susceptibility locus for BP in the 12q24.31 chromosomal region. Here, we investigated the possible involvement of the SMRT/N-CoR2 gene, which encodes for the nuclear receptor co-repressor 2. SMRT/N-CoR2 was retained as a candidate gene for BP because of its location within our candidate gene region and its interactions with thyroid hormone receptors. We screened SMRT/N-CoR2 for the presence of polymorphism/mutation in coding sequences and exon-intron junctions. Four non-synonymous SNPs and a polyglutamine tract (CAG repeat) in the coding exon 14 were analyzed in a case/control sample from the Saguenay-Lac-St-Jean (SLSJ) area of Quebec (213 cases and 214 controls). Our data indicated no significant allelic/genotypic association between any of the five mutations and bipolar phenotype when they were considered either individually or as haplotypes. Finally, the CAG repeat observed in SMRT/N-CoR2 did not demonstrate allelic instability and consequently it is unlikely that this polymorphism could be involved in the anticipation phenomenon reported for BP.     

Differential expression of angiopoietins 1 and 2 and their receptor Tie-2 in human endometrium

Angiogenesis, the growth of new capillaries from pre-existing blood vessels, is a physiological process involved in both normal menstrual cycling and implantation of the embryo. So far, very little is known about the expression of angiopoietins, growth factors involved in angiogenesis, in human endometrium. Both angiopoietin-1 (Ang-1) and angiopoietin-2 (Ang-2) are ligands for the endothelial cell-specific receptor tyrosine kinase Tie-2. In this study we determined the mRNA expression of Ang-1, Ang-2 and Tie-2 by quantitative competitive RT/(QC)-PCR (including specifically designed competitor cDNA) in biopsied human endometrium throughout the menstrual cycle. We detected the mRNA for the angiopoietins in 30 out of 32 endometrial biopsies (94%), covering early proliferative (n = 4), mid proliferative (n = 12), late proliferative (n = 3), early secretory (n = 3), mid secretory (n = 5) and late secretory (n = 3) phases. Analysis of the target/competitor ratios (QC-PCR) revealed that Ang-1 mRNA expression was significantly up-regulated (P = 0.027) during the secretory phase of the menstrual cycle. In contrast, the expression levels of both Ang-2 mRNA and Tie-2 mRNA showed only minor variations at different cycle stages. These findings were confirmed by the relative expression ratio of Ang-1 versus Ang-2 in a multiplex PCR. The expression of Ang-1, Ang-2 and Tie-2 mRNA was detected in both isolated endometrial epithelial and stromal cell fractions. Immunohistochemical localization of the proteins revealed qualitative differences in both cell type and cycle stage expression. In conclusion, the enhanced Ang-1 expression during the secretory phase might serve to stabilize the newly developed blood vessels.     

Progressive rise in the expression of interleukin-6 in human endometrium during menstrual cycle is initiated during the implantation window

In order to be prepared for implantation, human endometriumundergoes a predictable series of proliferative and secretorychanges. Cytokines play an important role in regulation of thesechanges. Therefore, in this study, we immunolocalized the cytokine,interleukin-6 (IL-6), its receptor and the signal transducergp130 in human endometrium throughout the menstrual cycle. Duringthe entire menstrual cycle, the IL-6 receptor and gp130 werefound primarily in the endometrial glands and to a lesser extentin the stroma. The immunoreactivity of these proteins did notchange in endometrial cells during the entire menstrual cyclewith an exception of reduced immunoreactivity of gp130 in endometrialglands during menstrual phase. Immunostaining showed that immunoreactiveIL-6 was weakly expressed in human endometrium during the proliferativephase. Strong immunoreactivity for IL-6 appeared in endometriumduring the putative 'implantation window'. Expression was byfar most pronounced both in the glandular and surface epithelialcells. The amount of immunoreactive IL-6 in the epithelium progressivelyincreased during the secretory/menstrual phases. During thelate secretory phase, only stromal cells in the upper functionalisexhibited immunoreactivity for IL-6. Western blot analysis corroboratedthe immunohistochemical data. Human endometrial IL-6 consistedof a protein with an apparent mobility of 26 kDa. The immunoreactiveband of IL-6 was weak in the proliferative phase. The expressionof this protein increased progressively during the secretory/menstrualphases. The findings show a cell-specific pattern of distributionfor immunoreactive IL-6 in human endometrium. The menstrualcycle-dependent expression of IL-6 suggests that this cytokinemay play a role in changes in endometrium that prepare thistissue for implantation and menstrual shedding.