The expression of interleukin-6 (IL-6), IL-6 receptor, and gp130-kilodalton glycoprotein in the rat decidua and a decidual cell line: regulation by 17beta-estradiol and prolactin

Synergistic induction of IL-6 production in human bronchial epithelial cells in vitro by nickel nanoparticles and lipopolysaccharide is mediated by STAT3 and C/EBPβ

We previously reported that delivery of nickel nanoparticles (NiNPs) and bacterial lipopolysaccharide (LPS) into the lungs of mice synergistically increased IL-6 production and inflammation, and male mice were more susceptible than female mice. The primary goal of this study was to utilize an in vitro human lung epithelial cell model (BEAS-2B) to investigate the intracellular signaling mechanisms that mediate IL-6 production by LPS and NiNPs. We also investigated the effect of sex hormones on NiNP and LPS-induced IL-6 production in vitro. LPS and NiNPs synergistically induced IL-6 mRNA and protein in BEAS-2B cells. TPCA-1, a dual inhibitor of IKK-2 and STAT3, blocked the synergistic increase in IL-6 caused by LPS and NiNPs, abolished STAT3 activation, and reduced C/EBPβ. Conversely, SC144, an inhibitor of the gp130 component of the IL-6 receptor, enhanced IL-6 production induced by LPS and NiNPs. Treatment of BEAS-2B cells with sex hormones (17β-estradiol, progesterone, or testosterone) or the anti-oxidant NAC, had no effect on IL-6 induction by LPS and NiNPs. These data suggest that LPS and NiNPs induce IL-6 via STAT3 and C/EBPβ in BEAS-2B cells. While BEAS-2B cells are a suitable model to study mechanisms of IL-6 production, they do not appear to be suitable for studying the effect of sex hormones.

The role of the prolactin/vasoinhibin axis in rheumatoid arthritis: an integrative overview

Rheumatoid arthritis (RA) is a chronic, autoimmune, inflammatory disease destroying articular cartilage and bone. The female preponderance and the influence of reproductive states in RA have long linked this disease to sexually dimorphic, reproductive hormones such as prolactin (PRL). PRL has immune-enhancing properties and increases in the circulation of some patients with RA. However, PRL also suppresses the immune system, stimulates the formation and survival of joint tissues, acquires antiangiogenic properties upon its cleavage to vasoinhibins, and protects against joint destruction and inflammation in the adjuvant-induced model of RA. This review addresses risk factors for RA linked to PRL, the effects of PRL and vasoinhibins on joint tissues, blood vessels, and immune cells, and the clinical and experimental data associating PRL with RA. This information provides important insights into the pathophysiology of RA and highlights protective actions of the PRL/vasoinhibin axis that could lead to therapeutic benefits.

Novel concepts on pregnancy clocks and alarms: redundancy and synergy in human parturition

The signals and mechanisms that synchronize the timing of human parturition remain a mystery and a better understanding of these processes is essential to avert adverse pregnancy outcomes. Although our insights into human labor initiation have been informed by studies in animal models, the timing of parturition relative to fetal maturation varies among viviparous species, indicative of phylogenetically different clocks and alarms; but what is clear is that important common pathways must converge to control the birth process. For example, in all species, parturition involves the transition of the myometrium from a relaxed to a highly excitable state, where the muscle rhythmically and forcefully contracts, softening the cervical extracellular matrix to allow distensibility and dilatation and thus a shearing of the fetal membranes to facilitate their rupture. We review a number of theories promulgated to explain how a variety of different timing mechanisms, including fetal membrane cell senescence, circadian endocrine clocks, and inflammatory and mechanical factors, are coordinated as initiators and effectors of parturition. Many of these factors have been independently described with a focus on specific tissue compartments.In this review, we put forth the core hypothesis that fetal membrane (amnion and chorion) senescence is the initiator of a coordinated, redundant signal cascade leading to parturition. Whether modified by oxidative stress or other factors, this process constitutes a counting device, i.e. a clock, that measures maturation of the fetal organ systems and the production of hormones and other soluble mediators (including alarmins) and that promotes inflammation and orchestrates an immune cascade to propagate signals across different uterine compartments. This mechanism in turn sensitizes decidual responsiveness and eventually promotes functional progesterone withdrawal in the myometrium, leading to increased myometrial cell contraction and the triggering of parturition. Linkage of these processes allows convergence and integration of the gestational clocks and alarms, prompting a timely and safe birth. In summary, we provide a comprehensive synthesis of the mediators that contribute to the timing of human labor. Integrating these concepts will provide a better understanding of human parturition and ultimately improve pregnancy outcomes.

Inhibition of IL-6 signaling pathway by curcumin in uterine decidual cells

IL-6 is a multifunctional pro-inflammatory cytokine and has been implicated in many gestational disorders including preterm birth. Currently, there are no appropriate therapeutic interventions available to circumvent inflammatory-mediated gestational disorders. Therefore, the goal of this study was to identify a safe and effective pharmacological compound to counterbalance inflammatory responses in the uterus. Curcumin, a naturally-occuring polyphenolic compound, has been widely used in alternative medicine to treat inflammatory diseases. However, the anti-inflammatory effect of curcumin has not been explored in uterine decidual cells, a major source of IL-6. Therefore, we examined the effect of curcumin on IL-6 expression using two types of uterine decidual cells 1) HuF cells, primary human fibroblast cells obtained from the decidua parietalis; 2) UIII cells, a rodent non-transformed decidual cell line. Curcumin treatment completely abrogated the expression of IL-1β-induced IL-6 in these cells. Curcumin also strongly inhibited the expression of gp130, a critical molecule in IL-6 signaling, whereas expression of IL-6R and sIL-6R was not affected. Curcumin also inhibited phosphorylation and nuclear localization of STAT3, a well-known downstream mediator of IL-6 signaling. Furthermore, curcumin attenuated IL-1β-induced IL-6 promoter reporter activity suggesting transcriptional regulation. To further understand whether NF-ҡB is involved in this inhibition, we examined the effect of curcumin on the expression of p50 and p65 subunits of NF-ҡB in decidual cells. Expression of IL-1β-induced p50 mRNA was repressed by curcumin while p65 mRNA was not affected. However, curcumin treatment dramatically inhibited both p50 and p65 protein levels and prevented its nuclear localization. This effect is at least partly mediated through the deactivation of IKK, since IL-1β-induced IKKα/β phosphorylation is decreased upon curcumin treatment. Our results not only revealed molecular mechanisms underlying curcumin action in uterine decidual cells but also suggest that this compound may have therapeutic potential for the prevention of inflammation-mediated preterm birth and other gestational disorders.

GDM Alters Expression of Placental Estrogen Receptor α in a Cell Type and Gender-Specific Manner

OBJECTIVE

The nuclear receptor estrogen receptor α (ERα) is one of the key players in energy balance, insulin resistance, and trophoblast differentiation. We tested the hypothesis that gestational diabetes mellitus (GDM) alters expression of placental ERα in a cell type-specific manner and that this regulation may involve epigenetic changes.

STUDY DESIGN

Expression of ERα was analyzed by immunohistochemistry using the semiquantitative immunoreactive score in 80 placentas (40 GDM/40 controls). Quantitative real-time polymerase chain reaction (PCR) measured ERα messenger RNA (mRNA) in decidual tissue. Methylation-specific PCR was performed to analyze cytosine-phosphatidyl-guanine-island methylation of the ERα promoter.

RESULTS

Expression of ERα protein is upregulated (P = .011) in GDM in extravillous trophoblasts but not in syncytiotrophoblast. Gestational diabetes mellitus downregulated ERα in decidual vessels only in pregnancies with male but not female fetuses. Furthermore, mRNA of the ERα encoding gene estrogen receptor gene 1 (ESR1) was increased (+1.77 fold) in GDM decidua when compared to controls (P = .024). In parallel, the promoter of ESR1 was methylated only in decidua of healthy control individuals but not in GDM.

CONCLUSION

Gestational diabetes mellitus affects expression of placental ERα in a cell type-dependent way, on epigenetic level. These data link GDM with epigenetic deregulations of ERα expression and open new insights into the intrauterine programming hypothesis of GDM.

17β-Estradiol inhibition of IL-6-Src and Cas and paxillin pathway suppresses human mesenchymal stem cells-mediated gastric cancer cell motility

Epidemiological studies demonstrate that the incidence and mortality of gastric cancer in women are lower than in men worldwide. Many studies have reported the delayed menopause and hormone replacement therapy are associated with a reduced risk for gastric cancer. It has been reported that endogenous estrogen lowers gastric cancer incidence in women, and cancer patients treated with estrogens have a lower subsequent risk of gastric cancer. It has been reported that estrogen decreases the progression of gastric cancer by inhibiting erbB-2 oncogene expression. Overexpression of estrogen receptor might inhibit the proliferation and invasion of MKN28 gastric cancer cells. Accumulating evidence suggests that bone marrow mesenchymal stem cells contribute to the progression of gastric cancer. However, it is unknown if 17β-estradiol (E2) treatment is sufficient to inhibit human bone marrow mesenchymal stem cells (HBMMSCs)-mediated cell motility in human gastric cancer cells. The results from human cytokine arrays have shown that HBMMSCs notably secrete interleukin 6 (IL-6) protein. Administration of IL-6-specific neutralizing antibody significantly inhibits HBMMSCs-mediated motility activity in human gastric cancer cells. Treatment of recombinant IL-6 soluble protein confirmed the role of IL-6 in mediating HBMMSCs-upregulated cell motility. IL-6 mainly upregulates motility activity via activation of Src signaling pathway in human gastric cancer cells. We further observed that E2 treatment inhibits HBMMSCs-induced cellular motility via suppressing the activation of IL-6-Src/Cas/paxillin signaling pathway in human gastric cancer cells. Collectively, these results suggest that E2 treatment significantly inhibits HBMMSCs-induced cellular motility in human gastric cancer cells.

Interleukin-6 in pregnancy and gestational disorders

IL6 is a multifunctional cytokine with pivotal roles in the inflammatory response and in directing T cell differentiation in adaptive immunity. IL6 is widely expressed in the female reproductive tract and gestational tissues, and exerts regulatory functions in embryo implantation and placental development, as well as the immune adaptations required to tolerate pregnancy. Here, we summarise the current understanding of how membrane-bound and soluble receptors mediate IL6 signalling to regulate leukocytes and non-haemopoietic cells. We review the published literature regarding the expression and actions of IL6 in the uterus, decidua and placenta, and studies implicating this cytokine in pregnancy disorders. Elevated IL6 is frequently evident in the altered cytokine profiles characteristic of unexplained infertility, recurrent miscarriage, preeclampsia and preterm delivery. Notably, there is compelling evidence indicating altered systemic IL6 trans-signalling in women prone to recurrent miscarriage, with excessive IL6 bioavailability potentially inhibiting generation of CD4+ T regulatory cells required for pregnancy tolerance. Insufficient local IL6 may also contribute to fetal loss, since IL6 expression is reduced in the endometrium of women with recurrent miscarriage, and in the fetal-placental tissue of CBA×DBA/2 mice. Consistent with the role of IL6 in key reproductive events, Il6 null mutant mice exhibit elevated fetal resorption and delayed parturition. Investigation of the association between IL6 signalling components and T cell responses in pregnant women, as well as detailed analysis of the maternal immune response in IL6-deficient mice, is now required to define the mechanisms by which this cytokine exerts influence on reproductive success.

The orphan nuclear receptor Nur77 regulates decidual prolactin expression in human endometrial stromal cells

Prolactin (PRL) is synthesized and released by several extrapituitary tissues, including decidualized stromal cells. Despite the important role of decidual PRL during pregnancy, little is understood about the factors involved in the proper regulation of decidual PRL expression. Here we present evidence that the transcription factor Nur77 plays an active role in decidual prolactin expression in human endometrial stromal cells (hESCs). Nur77 mRNA expression in hESCs was significantly increased after decidualization stimulated by 8-Br-cAMP and medroxyprogesterone acetate (MPA). Adenovirus-mediated overexpression of Nur77 in hESCs markedly increased PRL mRNA expression and enhanced decidual PRL promoter (dPRL/-332Luc) activity in a concentration-dependent manner. Furthermore, knockdown of Nur77 in hESCs significantly decreased decidual PRL promoter activation and substantially attenuated PRL mRNA expression and PRL secretion (P < 0.01) induced by 8-Br-cAMP and MPA. These results demonstrate that Nur77 is a novel transcription factor that contributes significantly to the regulation of prolactin gene expression in human endometrial stromal cells.

Interleukin-6 is an essential determinant of on-time parturition in the mouse

IL-6 abundance in amniotic fluid and uterine tissues increases in late gestation or with infection-associated preterm labor. A role in regulation of labor onset is suggested by observations that IL-6 increases expression of genes controlling prostaglandin synthesis and signaling in isolated uterine cells, but whether IL-6 is essential for normal parturition is unknown. To evaluate the physiological role of IL-6 in parturition in mice, we investigated the effect of Il6 null mutation on the timing of parturition and expression of genes associated with uterine activation. Il6 null mutant mice delivered 24 h later than wild-type mice, although circulating progesterone fell similarly in both genotypes during the prepartal period. Il6 null mutant mice were also refractory to low doses of lipopolysaccharide sufficient to induce preterm delivery in wild-type mice. The characteristic late-gestation elevation in uterine expression of Oxtr mRNA encoding oxytocin receptor, and peripartal increases in Ptgfr and Ptgs2 mRNAs regulating prostaglandin synthesis and signaling were delayed by 24 h in Il6 null mutant mice. Conversely, Ptger4 mRNA encoding the prostaglandin E receptor-4 was abnormally elevated in late-gestation in Il6 null mutant mice. Administration of recombinant IL-6 from d 11.5 postcoitum until term restored the normal timing of delivery and normalized Ptger4 mRNA expression in late gestation. We conclude that IL-6 has a key role in controlling the progression of events culminating in parturition and that it acts downstream of luteolysis in the uterus to regulate genes involved in the prostaglandin-mediated uterine activation cascade.

HoxA-11 and FOXO1A cooperate to regulate decidual prolactin expression: towards inferring the core transcriptional regulators of decidual genes

During the menstrual cycle, the ovarian steroid hormones estrogen and progesterone control a dramatic transcriptional reprogramming of endometrial stromal cells (ESCs) leading to a receptive state for blastocyst implantation and the establishment of pregnancy. A key marker gene of this decidualization process is the prolactin gene. Several transcriptional regulators have been identified that are essential for decidualization of ESCs, including the Hox genes HoxA-10 and HoxA-11, and the forkhead box gene FOXO1A. While previous studies have identified downstream target genes for HoxA-10 and FOXO1A, the role of HoxA-11 in decidualization has not been investigated. Here, we show that HoxA-11 is required for prolactin expression in decidualized ESC. While HoxA-11 alone is a repressor on the decidual prolactin promoter, it turns into an activator when combined with FOXO1A. Conversely, HoxA-10, which has been previously shown to associate with FOXO1A to upregulate decidual IGFBP-1 expression, is unable to upregulate PRL expression when co-expressed with FOXO1A. By co-immunoprecipitation and chromatin immunoprecipitation, we demonstrate physical association of HoxA-11 and FOXO1A, and binding of both factors to an enhancer region (−395 to −148 relative to the PRL transcriptional start site) of the decidual prolactin promoter. Because FOXO1A is induced upon decidualization, it serves to assemble a decidual-specific transcriptional complex including HoxA-11. These data highlight cooperativity between numerous transcription factors to upregulate PRL in differentiating ESC, and suggest that this core set of transcription factors physically and functionally interact to drive the expression of a gene battery upregulated in differentiated ESC. In addition, the functional non-equivalence of HoxA-11 and HoxA-10 with respect to PRL regulation suggests that these transcription factors regulate distinct sets of target genes during decidualization.

Regulation of transcription factors and repression of Sp1 by prolactin signaling through the short isoform of its cognate receptor

Prolactin (PRL) affects the development and function of the reproductive system by binding to two types of receptors, which differ by the size of their intracellular domain in rodents. Whereas the signaling pathway through the long form of the receptor (PRL-RL) is well characterized, signaling through the short form (PRL-RS) remains obscure. In this investigation, we examined transcription factors regulated by PRL in the ovary and decidua of mice expressing only PRL-RS in a PRL receptor null background. These mice provide a powerful in vivo model to study the selective signaling mechanism of PRL through PRL-RS independent of PRL-RL. We also examined the regulation of transcription factors in ovarian and uterine cell lines stably transfected with PRL-RS or PRL-RL. We focused our investigation on transcription factors similarly regulated in both these tissues and clearly established that signaling through PRL-RS does not activate the JaK/Stat in vivo but leads to severe down-regulation of Sp1 expression, DNA binding activity, and nuclear localization, events that appear to involve the calmodulin-dependent protein kinase pathway. Our in vivo and in culture data demonstrate that the PRL-RS activates a signaling pathway distinct from that of the PRL-RL.

Downregulation of cilia-localized Il-6Rα by 17β-estradiol in mouse and human fallopian tubes

The action of interleukin-6 (IL-6) impacts female reproduction. Although IL-6 was recently shown to inhibit cilia activity in human fallopian tubes in vitro, the molecular mechanisms underlying IL-6 signaling to tubal function remain elusive. Here, we investigate the cellular localization, regulation, and possible function of two IL-6 receptors (IL-6Rα and gp130) in mouse and human fallopian tubes in vivo. We show that IL-6Rα is restricted to the cilia of epithelial cells in both mouse and human fallopian tubes. Exogenous 17β-estradiol (E2), but not progesterone (P4), causes a time-dependent decrease in IL-6Rα expression, which is blocked by the estrogen receptor (ER) antagonist ICI-182,780. Exposure of different ER-selective agonists propyl-(1H)-pyrazole-1,3,5-triyl-trisphenol or 2,3-bis-(4-hydroxyphenyl)-propionitrile demonstrated an ER subtype-specific regulation of IL-6Rα in mouse fallopian tubes. In contrast to IL-6Rα, gp130 was detected in tubal epithelial cells in mice but not in humans. In humans, gp130 was found in the muscle cells and was decreased in the periovulatory and luteal phases during the reproductive cycles, indicating a species-specific expression and regulation of gp130 in the fallopian tube. Expression of tubal IL-6Rα and gp130 in IL-6 knockout mice was found to be normal; however, E2 treatment increased IL-6Rα, but not gp130, in IL-6 knockout mice when compared with wild-type mice. Furthermore, expression levels of IL-6Rα, but not gp130, decreased in parallel with estrogenic accelerated oocyte-cumulus complex (OCC) transport in mouse fallopian tubes. Our findings open the posibility that cilia-specific IL-6Rα may play a role in the regulation of OCC transport and suggest an estrogen-regulatory pathway of IL-6Rα in the fallopian tube.

Novel tumor sampling strategies to enable microarray gene expression signatures in breast cancer: a study to determine feasibility and reproducibility in the context of clinical care

Feasibility and reproducibility of microarray biomarkers in clinical settings are doubted because of reliance on fresh frozen tissue. We sought to develop and validate a paradigm of frozen tissue collection from early breast tumors to enable use of microarray in oncology practice. Frozen core needle biopsies (CNBx) were collected from 150 clinical stage I patients during image-guided diagnostic biopsy and/or surgery. Histology and tumor content from frozen cores were compared to diagnostic specimens. Twenty-eight patients had microarray analysis to examine accuracy and reproducibility of predictive gene signatures developed for estrogen receptor (ER) and HER2. One hundred twenty-seven (85%) of 150 patients had at least one frozen core containing cancer suitable for microarray analysis. Larger tumor size, ex vivo biopsy, and use of a new specimen device increased the likelihood of obtaining adequate specimens. Sufficient quality RNA was obtained from 90% of tumor cores. Microarray signatures predicting ER and HER2 expression were developed in training sets of up to 363 surgical samples and were applied to microarray data obtained from core samples collected in clinical settings. In these samples, prediction of ER and HER2 expression achieved a sensitivity/specificity of 94%/100%, and 82%/72%, respectively. Predictions were reproducible in 83-100% of paired samples. Frozen CNBx can be readily obtained from most breast cancers without interfering with pathologic evaluation in routine clinical settings. Collection of tumor tissue at diagnostic biopsy and/or at surgery from lumpectomy specimens using image guidance resulted in sufficient samples for array analysis from over 90% of patients. Sampling of breast cancer for microarray data is reproducible and feasible in clinical practice and can yield signatures predictive of multiple breast cancer phenotypes.

Adaptive changes in the transcription factor HoxA-11 are essential for the evolution of pregnancy in mammals

Evolutionary change in gene regulation can result from changes in cis-regulatory elements, leading to differences in the temporal and spatial expression of genes or in the coding region of transcription factors leading to novel functions or both. Although there is a growing body of evidence supporting the importance of cis-regulatory evolution, examples of protein-mediated evolution of novel developmental pathways have not been demonstrated. Here, we investigate the evolution of prolactin (PRL) expression in endometrial cells, which is essential for placentation/pregnancy in eutherian mammals and is a direct regulatory target of the transcription factor HoxA-11. Here, we show that (i) endometrial PRL expression is a derived feature of placental mammals, (ii) the PRL regulatory gene HoxA-11 experienced a period of strong positive selection in the stem-lineage of eutherian mammals, and (iii) only HoxA-11 proteins from placental mammals, including the reconstructed ancestral eutherian gene, are able to up-regulate PRL from the promoter used in endometrial cells. In contrast, HoxA-11 from the reconstructed therian ancestor, opossum, platypus, and chicken are unable to up-regulate PRL expression. These results demonstrate that the evolution of novel gene expression domains is not only mediated by the evolution of cis-regulatory elements but can also require evolutionary changes of transcription factor proteins themselves.

Disturbances in the LIF pathway in the endometrium among women with unexplained infertility

OBJECTIVE

To study the expression of leukemia inhibitory factor (LIF), its receptors LIFR and gp130, and its inhibitor SOCS1 in endometria from fertile women and infertile women with unexplained infertility. Signaling through the LIF pathway is involved in maintenance of a receptive state of human endometrium. Impaired endometrial receptivity may be a cause of female infertility.

DESIGN

Prospective clinical study.

SETTING

Hospital-based IVF unit and university-affiliated reproductive research laboratories.

PATIENT(S)

Twenty-six healthy fertile women and 14 women with unexplained infertility.

INTERVENTION(S)

Endometrial biopsy.

MAIN OUTCOME MEASURE(S)

Pinopode formation, expression of LIF, LIFR, gp130, and SOCS1 protein and mRNA in endometrial biopsies.

RESULT(S)

The expression of LIFR in the endometrium was negatively correlated to the expression of SOCS1 and positively correlated to the formation of pinopodes. In control fertile women, simultaneous intense apical staining of LIFR and gp130 together with faint SOCS1 staining was observed in epithelial cells, whereas the opposite was seen in most women with unexplained infertility.

CONCLUSION(S)

Unexplained infertility in some women might be explained by disturbances in the LIF pathway in midsecretory-phase endometrium.

Decidual prolactin silences the expression of genes detrimental to pregnancy

Although the main role of prolactin (PRL) in pregnant rodents is to sustain progesterone production by the corpus luteum, progesterone treatment of PRL or PRL receptor (PRL-R) null mice is unable to prevent fetal loss. We have previously shown that the rat decidua is a site of PRL production and action. In this report, we examined the hypothesis, using PRL null mice and rat decidual cell culture, that the absence of this hormone leads to the expression in the decidua of genes detrimental to pregnancy. The results show that decidual growth is normal in PRL null mice treated with PRL, progesterone, or their combination. However, the decidua of mice treated with progesterone starts expressing IL-6 and 20alpha-hydroxysteroid dehydrogenase (20alpha-HSD), two proteins absent from the decidua of wild-type mice and involved, respectively, in inflammation and progesterone catabolism. The expression of both IL-6 and 20alpha-HSD is prevented by PRL treatment. Our results further suggest that PRL inhibition of 20alpha-HSD expression is at the level of transcription and that decidual PRL (dPRL) inhibits 20alpha-HSD promoter activity. Inhibitors of Janus kinase 2 (Jak2) but not other kinases prevent dPRL down-regulation of the 20alpha-HSD promoter. Furthermore, cotransfection of the 20alpha-HSD promoter with expression vectors of constitutively active PRL-R, Jak2, or signal transducer and activator of transcription 5b (Stat5b) leads to substantial inhibition of promoter activity. Taken together, our investigation provides an explanation for the inability of progesterone to sustain pregnancy in PRL null mice and suggests that dPRL plays an important role in pregnancy by repressing the expression of IL-6 and 20alpha-HSD in the decidua. The study also demonstrates that PRL signals through the Jak2/Stat5 pathway to down-regulate 20alpha-HSD expression in the decidua.

The role of interleukin-11 in pregnancy involves up-regulation of alpha2-macroglobulin gene through janus kinase 2-signal transducer and activator of transcription 3 pathway in the decidua

IL-11 expressed by endometrial stromal cells is crucial for normal pregnancy. IL-11 receptor alpha (IL-11Ralpha) null mice are infertile due to abnormal development of the placenta. In these mice, the mesometrial decidual tissue, which is the site of trophoblast invasion, thins and disappears at mid-pregnancy. Degeneration of the decidua is accompanied by uncontrolled trophoblast invasion. In this report, we show, using IL-11Ralpha null mice, that a defect in IL-11 signaling in the decidua leads to severe down-regulation of alpha(2)-macroglobulin (alpha(2)-MG), a metalloproteinase inhibitor crucial for limiting trophoblast invasion. We also present evidence, using uterine stromal cells that decidualize in culture, that IL-11 robustly stimulates the endogenous alpha(2)-MG expression and enhances alpha(2)-MG promoter activity. Serial 5' deletion and internal deletion of the promoter reveal two important signal transducer and activator of transcription (Stat) binding sites. Mutation of either one of these motifs decreases IL-11 stimulation, whereas double mutation prevents IL-11 action. We also found that IL-11 activates Janus kinase 2 (Jak2) and induces rapid phosphorylation, nuclear translocation, and promoter binding activity of Stat3 in decidual cells, whereas Jak1, Tyk2, and Stat5 activities are not affected. In addition, Jak2 inhibitor totally prevents alpha(2)-MG expression in decidual cells. Taken together, results of this investigation provide, at least in part, an explanation for the overinvasiveness of the trophoblast in IL-11Ralpha null mice and reveal, for the first time, that IL-11 signals through the Jak2/Stat3 pathway in decidual cells to stimulate the expression of alpha(2)-MG, a protease inhibitor essential for normal placentation in pregnancy.

LS14: a novel human adipocyte cell line that produces prolactin

Adipose tissue is an integral component within the endocrine system. Adipocytes produce numerous bioactive substances, and their dysregulation has serious pathophysiological consequences. We previously reported that human adipose tissue from several depots produces significant amounts of prolactin (PRL). To study locally produced PRL, we sought an acceptable in vitro model. Consequently, we developed an adipocyte cell line derived from a metastatic liposarcoma. The cell line, designated LS14, has been in continuous culture for 2 yr. These cells exhibit many properties of primary preadipocytes, including the ability to undergo terminal differentiation, as judged by morphological alterations, lipid accumulation, and increase in glycerol-3-phosphate dehydrogenase. LS14 cells express many adipose-associated genes, such as adipocyte fatty acid-binding protein (aP(2)), hormone-sensitive lipase, lipoprotein lipase, preadipocyte factor 1, adiponectin, leptin, and IL-6. Similar to primary adipocytes, LS14 cells also produce and respond to PRL, thus making them an attractive model to study adipose PRL production and function. The expression of PRL was confirmed at the transcriptional level by RT-PCR, and PRL secretion was determined by the Nb2 bioassay. Addition of exogenous PRL to LS14 cells resulted in a dose-dependent inhibition of IL-6 release. In summary, we have established a novel human adipocyte cell line with many characteristics of primary adipocytes. The LS14 cells open up new avenues for research on human adipocyte biology and add to the repertoire of nonpituitary, PRL-producing cell lines.

A hind limb tourniquet induces interleukin-6 expression in a rat dorsal root ganglion

We investigated the mRNA levels of interleukin-6-related genes in a rat dorsal root ganglion after application of a tourniquet to a hind limb in order to identify the molecules that are induced immediately after peripheral nerve injury at the early stage. Induction of interleukin-6 and upregulation of glycoprotein 130 mRNA expressions were observed in the ipsilateral dorsal root ganglion at 4 h after tourniquet application. Interleukin-6 protein was detected in small-sized and medium-sized dorsal root ganglion cells by immunohistochemical analysis. The induction of interleukin-6 expression is likely to play a role in the protection of injured neurons perhaps related to growth of their axons. Glycoprotein 130 might also account for the inhibitory effects following nerve injury.

Cloning and characterization of a 5' regulatory region of the prolactin receptor-associated protein/17{beta} hydroxysteroid dehydrogenase 7 gene

Prolactin receptor-associated protein (PRAP) originally cloned in our laboratory was shown to be a novel, luteal isoform of 17beta hydroxysteroid dehydrogenase 7 (17betaHSD7). In this study, we cloned the promoter region of rat PRAP/17betaHSD7 and investigated the mechanisms regulating both basal activity and LH-induced repression of this promoter. Truncated and site-specific mutants of PRAP/17betaHSD7 promoter identified two enhancer regions that contained highly conserved Sp1 binding site and bound Sp1 from nuclear extracts of both corpora lutea and a rat luteal cell line. Repression of PRAP/17betaHSD7 expression and promoter activity by human chorionic gonadotropin/forskolin was localized to a -52-bp proximal segment of the promoter. This region contained a conserved CCAAT site and bound nuclear factor Y; binding of this transcription factor was inhibited by human chorionic gonadotropin in vivo. Furthermore, mutation of the nuclear factor Y site in the -52-bp promoter-reporter construct abolished forskolin-mediated inhibition of the promoter in a rat luteal cell line. In summary, we have identified the promoter elements involved in the basal expression of PRAP/17betaHSD7. We have also found that LH-mediated repression of this gene is at the level of transcription and involves inhibition of nuclear factor YA binding to the CCAAT site within the proximal promoter.

Protective effects of estradiol on TRAIL-induced apoptosis in a human oligodendrocytic cell line: evidence for multiple sites of interactions

Demyelinating diseases are high impact neurological disorders. Steroids are regarded as protective molecules in the susceptibility to these diseases. Here, we studied the interactions between tumour necrosis factor-related apoptosis-inducing ligand (TRAIL), a potent proapoptotic molecule toxic to oligodendrocytes, and 17-beta-estradiol (E-17-beta), in human oligodendrocytic MO3.13 cells. Exposure of cells to TRAIL resulted in the upregulation of both death receptors DR4 and DR5 and apoptosis, as well as the activation of caspase-8 and -3, increased phosphorylation of Jun-N-terminal kinase and p38 kinase, and the reduction of bcl-2 and bcl-xL proteins. TRAIL-mediated MO3.13 cell apoptosis was abrogated by the dominant-negative form of the adaptor protein FADD and by caspase inhibitors. Preincubation with E-17-beta completely prevented both TRAIL-induced DR4 and DR5 upregulation and apoptosis. Estrogen-induced cytoprotection was time and concentration dependent and reverted by antiestrogens. Estrogen treatment per se reduced kinase phosphorylation, and upregulated bcl-2 and bcl-xL proteins. In conclusion, our data show that the detrimental role of TRAIL on oligodendrocytes can be effectively counteracted by estrogens, thus suggesting that the underlying molecular interactions can be of potential relevance in characterizing novel targets for therapy of demyelinating disorders.

Estrogen regulation of growth hormone action

GH plays a pivotal role in regulating body growth and development, which is modulated by sex steroids. A close interplay between estrogen and GH leads to attainment of gender-specific body composition during puberty. The physiological basis of the interaction is not well understood. Most previous studies have focused on the effects of estrogen on GH secretion. There is also strong evidence that estrogen modulates GH action independent of secretion. Oral but not transdermal administration of estrogen impairs the metabolic action of GH in the liver, causing a fall in IGF-I production and fat oxidation. This results in a loss of lean tissue and a gain of body fat in postmenopausal women and an impairment of GH effect in hypopituitary women on GH replacement. The negative metabolic sequelae are potentially important because of the widespread use of oral estrogen and estrogen-related compounds. Estrogen affects GH action at the level of receptor expression and signaling. More recently, estrogen has been shown to inhibit Janus kinase/signal transducer and activator of transcription signaling by GH via the induction of suppressor of cytokine signaling-2, a protein inhibitor for cytokine signaling. This represents a novel paradigm of steroid regulation of cytokine receptors and is likely to have significance for a diverse range of cytokine function.

Phytoestrogen genistein acts as an estrogen agonist on human osteoblastic cells through estrogen receptors alpha and beta

Genistein, a soybean isoflavone, has estrogen-like activity in mammals, including the prevention of bone loss. However, whether its mechanism of action on bone turnover is distinct from that of estrogen or raloxifene is unknown. Although genistein has been reported to bind both estrogen receptor (ER) isoforms (alpha and beta), little is known concerning differential activation of gene expression via these ER isoforms. To examine this question, comparison of the responses of normal fetal osteoblast (hFOB) cells stably expressing either ERalpha (hFOB/ERalpha9) or ERbeta (hFOB/ERbeta6), to treatment with genistein, 17beta-estradiol (E(2)) or raloxifene were conducted. In hFOB/ERalpha9 cells, both genistein and E(2) increased the endogenous gene expression of the progesterone receptor (PR), the proteoglycan versican, and alkaline phosphatase (AP), but inhibited osteopontin (OP) gene expression and interleukin-6 (IL-6) protein levels. Raloxifene had no effect on these bone markers. Genistein, but not raloxifene, also mimicked E(2) action in the hFOB/ERbeta6 cells increasing PR gene expression and inhibiting IL-6 production. To determine whether the gene regulatory actions of genistein in human osteoblast cells occur at the level of transcription, its action on the transcriptional activity of a PR-A promoter-reporter construct was assessed. Both genistein and E(2) were found to stimulate the PR promoter in the hFOB cell line when transiently co-transfected with either ERalpha or ERbeta. Whereas hFOB cell proliferation was unaffected by E(2), raloxifene or genistein at low concentrations, higher concentrations of genistein, displayed significant inhibition. Together, these findings demonstrate that genistein behaves as a weak E(2) agonist in osteoblasts and can utilize both ERalpha and ERbeta.

Decidual activin: its role in the apoptotic process and its regulation by prolactin

Successful pregnancy requires profound differentiation and reorganization of the uterine tissues including, as pregnancy progresses, extensive apoptosis of decidual tissue to accommodate the developing conceptus. We have previously shown a positive correlation between expression of activin A and apoptosis in the decidua and have also shown that expression of activin A occurs at the time when prolactin (PRL) receptors disappear from decidual cells. The goals of this study were to examine whether activin A plays a role in decidual apoptosis and whether expression of activin A in the decidua is regulated by PRL and placental lactogens. Studies were carried out using primary rat decidual cells, a decidual cell line (GG-AD), and PRL null mice. Treatment of decidual cells with activin A significantly increased DNA degradation, caspase 3 activity, and caspase 3 mRNA expression. However, this effect was observed only in the absence of endogenous activin production by these cells. Addition of follistatin to decidual cells that were producing activin A decreased both caspase 3 activity and mRNA expression. Similarly, addition of activin-blocking antibodies to cultures of GG-AD cells, which also produce activin A, caused a reduction in both DNA degradation and caspase 3 activity. PRL and placental lactogens caused an inhibition of activin A mRNA expression in primary decidual cells. Even more convincingly, decidua of PRL null mice expressed abundant activin A at a time when no expression of this hormone is detected in wild-type mice and treatment of PRL null mice with PRL caused a profound inhibition of activin A mRNA expression. In summary, our investigations into the role and regulation of decidual activin have revealed that activin A can induce cell death in the decidua and that its expression is under tight regulation by PRL and placental lactogens.

Changes in proinflammatory cytokine activity after menopause

There is now a large body of evidence suggesting that the decline in ovarian function with menopause is associated with spontaneous increases in proinflammatory cytokines. The cytokines that have obtained the most attention are IL-1, IL-6, and TNF-alpha. The exact mechanisms by which estrogen interferes with cytokine activity are still incompletely known but may potentially include interactions of the ER with other transcription factors, modulation of nitric oxide activity, antioxidative effects, plasma membrane actions, and changes in immune cell function. Experimental and clinical studies strongly support a link between the increased state of proinflammatory cytokine activity and postmenopausal bone loss. Preliminary evidence suggests that these changes also might be relevant to vascular homeostasis and the development of atherosclerosis. Better knowledge of the mechanisms and the time course of these interactions may open new avenues for the prevention and treatment of some of the most prevalent and important disorders in postmenopausal women.

Sexual dimorphism in the pituitary-adrenal response to tumor necrosis factor-alpha, but not to interleukin-6, in the rat

It is known that the pituitary-adrenal responses to lipopolysaccharide and interleukin (IL)-1 are sexually dimorphic in rodents, with females having an enhanced secretion of adrenocorticotropin (ACTH) and corticosterone. This study investigated whether the ACTH and corticosterone responses to tumor necrosis factor (TNF)-alpha and IL-6, two principal proinflammatory cytokines, are also modulated by the sex steroid milieu in the rat. Mature male and female rats received an intravenous administration of TNF-alpha(10 microg/kg) and IL-6 (10 microg/kg), and changes in plasma ACTH and corticosterone levels were determined over time. The effect of gonadectomy on the hormonal responses was also examined in both sexes. TNF-alpha induced significantly higher responses of ACTH and corticosterone in females than in males, and this sexual difference was abolished by gonadectomy in both sexes. By contrast, the hormonal responses to IL-6 were not significantly affected by either gender or gonadectomy. These results suggest a sex steroid-dependent modulation of the TNF-alpha-induced, but not the IL-6-induced, ACTH and corticosterone secretion in the rat. Further evidence for the sexually dimorphic neuroimmunoendocrine activity is reported herein.

Estrogen regulation of human osteoblast function is determined by the stage of differentiation and the estrogen receptor isoform

Although osteoblasts have been shown to respond to estrogens and express both isoforms of the estrogen receptor (ER alpha and ER beta), the role each isoform plays in osteoblast cell function and differentiation is unknown. The two ER isoforms are known to differentially regulate estrogen-inducible promoter-reporter gene constructs, but their individual effects on endogenous gene expression in osteoblasts have not been reported. We compared the effects of 17 beta-estradiol (E) and tamoxifen (TAM) on gene expression and matrix formation during the differentiation of human osteoblast cell lines stably expressing either ER alpha (hFOB/ER alpha 9) or ER beta (hFOB/ER beta 6). Expression of the appropriate ER isoform in these cells was confirmed by northern and western blotting and the responses to E in the hFOB/ER beta 6 line were abolished by an ER beta-specific inhibitor. The data demonstrate that (1) in both the hFOB/ER cell lines, certain responses to E or TAM (including alkaline phosphatase, IL-6 and IL-11 production) are more pronounced at the late mineralization stage of differentiation compared to earlier stages, (2) E exerted a greater regulation of bone nodule formation and matrix protein/cytokine production in the ER alpha cells than in ER beta cells, and (3) the regulated expression of select genes differed between the ER alpha and ER beta cells. TAM had no effect on nodule formation in either cell line and was a less potent regulator of gene/protein expression than E. Thus, both the ER isoform and the stage of differentiation appear to influence the response of osteoblast cells to E and TAM.

Reactive astrocytes express estrogen receptors in the injured primate brain

Previous studies have suggested that estrogen may regulate the expression of genes related to the inflammatory response within the nervous system, particularly within glia. In the present study, we examined whether injury induces estrogen sensitivity in reactive glia in the primate brain. Three adult Macaca fascicularis (cynomolgous) monkeys received unilateral fimbria fornix transections followed by chronic intracranial cannula implants through which a vehicle solution was infused intracerebroventricularly for a 4-week period. Astrocytes adjacent to areas of parenchymal disruption caused either by the lesion or by the instrumentation procedure became reactive, as evidenced by cellular hypertrophy and up-regulation of glial fibrillary acidic protein (GFAP) immunolabeling. Of note, specific estrogen receptor-alpha immunolabeling also was induced adjacent to injured regions, and this labeling strictly colocalized with GFAP immunoreactivity upon double fluorescent confocal immunolabeling. Induction of estrogen receptor immunoreactivity in reactive astrocytes occurred in all monkeys examined, whereas nonreactive glia distant from disrupted regions did not exhibit estrogen receptor labeling. Thus, expression of estrogen receptors is up-regulated in reactive astrocytes of the primate brain, potentially allowing estrogen to modulate aspects of the central nervous system's inflammatory response to injury.

IL-6 up-regulates CNTF mRNA expression and enhances neurite regeneration

Interleukin-6 (IL-6) is a neurotrophic cytokine, however, its direct effect on nerve regeneration has not been well characterized. We therefore examined the effect of IL-6 on neurite regeneration using the rat dorsal root ganglion. IL-6 significantly enhanced neurite regeneration from transected nerve terminals. We also examined the mRNA expression of IL-6 family cytokines and their receptors during the regeneration. The mRNA expressions of IL-6, IL-6 receptor, leukemia inhibitory factor (LIF), ciliary neurotrophic factor (CNTF) receptor alpha, and LIF receptor beta showed no significant differences by the addition of IL-6. In contrast, IL-6 enhanced the mRNA expression of gp130 and CNTF. In addition, CNTF significantly increased neurite regeneration when added exogenously. Our data suggest that IL-6 enhanced regeneration via up-regulating CNTF expression.

Characterization of a rat uterine cell line, U(III) cells: prolactin (PRL) expression and endogenous regulation of PRL-dependent genes; estrogen receptor beta, alpha(2)-macroglobulin, and decidual PRL involving the Jak2 and Stat5 pathway

Decidualization of endometrial stroma in the rat induces the expression and secretion of rat decidual PRL (rdPRL). Recently, we have generated a nontransformed rat uterine stromal cell line (U(III)) that decidualizes spontaneously in culture. In this report, we have established by immunocytochemistry, RT-PCR, Western blot analysis, labeled amino acid incorporation and RIA that these cells express the rat PRL messenger RNA as well as synthesize and secrete PRL. We have also cloned by RT-PCR a 403-bp complementary DNA fragment whose sequence is identical with that of rat pituitary PRL. In addition, U(III) cells express the PRL receptor (PRL-R) long form, all the components involved in the PRL signal transduction pathway, estrogen receptor beta (ER beta) and alpha(2)-macroglobulin (alpha(2)-MG), which are known to be PRL-regulated genes. However, when U(III) cells were treated with PRL, no regulation of these genes was observed. Moreover, in these cells, the PRL signaling components: the tyrosine kinase Jak2 and the transcription factor Stat5 were endogenously phosphorylated and their phosphorylation states were not enhanced in the presence of exogenous PRL. To examine whether the endogenously secreted PRL affects the expression of PRL-regulated genes, U(III) cells were treated with either an anti-PRL receptor antibody or a Jak2 inhibitor, AG490. The anti-PRL receptor antibody decreased alpha(2)-MG expression. AG490 inhibited Jak2 and Stat5 phosphorylation, prevented Stat5 binding to its DNA consensus sequence, and also caused a dose-dependent down-regulation of alpha(2)-MG and ER beta expression. In contrast, AG490 enhanced PRL mRNA levels. In summary, we have established that the U(III) stromal cells of uterine origin produce PRL. Furthermore, we have shown for the first time that decidual PRL may act locally to activate the Jak2/Stat5 pathway and up-regulate important genes involved in decidual growth and placentation.