Regulation of interleukin-8 gene expression in human endometrial cells in culture

CXC chemokines influence immune surveillance in immunological disorders: Polycystic ovary syndrome and endometriosis

Reproductive health is a worldwide challenge, but it is of particular significance to women during their reproductive age. Several female reproductive problems, including polycystic ovary syndrome (PCOS) and endometriosis, affect about 10 % of women and have a negative impact on their health, fertility, and quality of life. Small, chemotactic, and secreted cytokines are CXC chemokines. Both PCOS and endometriosis demonstrate dysregulation of CXC chemokines, which are critical to the development and progression of both diseases. Recent research has shown that both in humans and animals, CXC chemokines tend to cause inflammation. It has also been found that CXC chemokines are necessary for promoting angiogenesis and inflammatory responses. CXC chemokine overexpression is frequently associated with poor survival and prognosis. CXC chemokine levels in PCOS and endometriosis patients impact their circumstances significantly. Hence, CXC chemokines have significant potential as diagnostic and prognostic biomarkers and therapeutic targets. The molecular mechanisms through which CXC chemokines promote inflammation and the development of PCOS and endometriosis are currently unknown. This article will discuss the functions of CXC chemokines in the promotion, development, and therapy of PCOS and endometriosis, as well as future research directions. The current state and future prospects of CXC chemokine -based therapeutic strategies in the management of PCOS and endometriosis are also highlighted.

Ovulation Induced by Intrauterine Seminal Plasma Increases Total Protein, PGE2, IL-8, and IL-1β in Uterine Fluid of Llamas (Lama glama)

The establishment of a state of immunotolerance in the female reproductive tract is important for embryo development, implantation and placentation. Llamas are induced ovulators and more than 98% of pregnancies occur in the left uterine horn. The objective of this study was to determine the uterine immune response of llamas in different stages of the reproductive cycle. Adult llamas (n = 20) were examined daily by transrectal ultrasonography to determine follicular growth and then randomly assigned to four groups: Follicular phase (n = 5); Luteal phase induced by an intramuscular administration of 50 ug of GnRH analogue (n = 5); Luteal phase induced by intrauterine infusion of seminal plasma (n = 5); and Luteal phase induced by mating (n = 5). Uterine fluid was collected separately from both uterine horns by non-surgical flushing to determine the presence of cells, total proteins and concentration of IL-1β, IL-6, IL-8, IFN γ, TNF-α and PGE2. Inflammatory cells were not observed in the uterine fluid and total protein pattern and inflammatory mediators did not differ between the left and the right horn amongst groups. Llamas treated with an intrauterine infusion of seminal plasma showed the highest concentration of total proteins, inflammatory cytokines PGE2, IL-8 and IL-1β in the uterine fluid. In conclusion, seminal plasma is made up of significant numbers of signaling molecules that are able to modify the uterine immune response in llamas.

Physiology of the Endometrium and Regulation of Menstruation

The physiological functions of the uterine endometrium (uterine lining) are preparation for implantation, maintenance of pregnancy if implantation occurs, and menstruation in the absence of pregnancy. The endometrium thus plays a pivotal role in reproduction and continuation of our species. Menstruation is a steroid-regulated event, and there are alternatives for a progesterone-primed endometrium, i.e., pregnancy or menstruation. Progesterone withdrawal is the trigger for menstruation. The menstruating endometrium is a physiological example of an injured or “wounded” surface that is required to rapidly repair each month. The physiological events of menstruation and endometrial repair provide an accessible in vivo human model of inflammation and tissue repair. Progress in our understanding of endometrial pathophysiology has been facilitated by modern cellular and molecular discovery tools, along with animal models of simulated menses. Abnormal uterine bleeding (AUB), including heavy menstrual bleeding (HMB), imposes a massive burden on society, affecting one in four women of reproductive age. Understanding structural and nonstructural causes underpinning AUB is essential to optimize and provide precision in patient management. This is facilitated by careful classification of causes of bleeding. We highlight the crucial need for understanding mechanisms underpinning menstruation and its aberrations. The endometrium is a prime target tissue for selective progesterone receptor modulators (SPRMs). This class of compounds has therapeutic potential for the clinical unmet need of HMB. SPRMs reduce menstrual bleeding by mechanisms still largely unknown. Human menstruation remains a taboo topic, and many questions concerning endometrial physiology that pertain to menstrual bleeding are yet to be answered.

Estradiol-regulated innate antiviral responses of human endometrial stromal fibroblasts

PROBLEM

The contribution of fibroblasts to innate immune protection of the human female reproductive tract (FRT) against viral pathogens is relatively unknown.

METHOD OF STUDY

Endometrial (EM), endocervical (Cx) and ectocervical (ECx) fibroblasts were isolated from hysterectomy patients and grown in vitro. Fibroblasts were treated with the viral mimic poly (I:C) in the presence or absence of the sex hormone estradiol (E2 ), with gene expression measured by real-time RT-PCR and protein secretion by ELISA.

RESULTS

Poly (I:C) induced the expression of the interferon-stimulated genes (ISG) MxA, OAS2 and APOBEC3G, and the cytokines MCP-1, IL-8, IL-6, CCL20, IFNβ and RANTES by fibroblasts from all three sites. ISG upregulation was dependent upon Type I IFN signaling. E2 inhibited the poly (I:C)-induced upregulation of MxA and OAS2 in EM fibroblasts, but not Cx or ECx fibroblasts. E2 upregulated SDF-1α by EM fibroblasts but had no effect on secretion of other cytokines either alone or in the presence of poly (I:C). Conditioned media (CM) from poly (I:C)-treated or E2 -treated fibroblasts significantly reduced HIV infection of CD4+ T cells.

CONCLUSION

Stromal fibroblasts represent a level of innate immune protection against viral pathogens in the FRT beyond that seen with epithelial cells and immune cells. Our findings indicate that fibroblasts FRT are selectively responsive to E2 , capable of initiating an antiviral response against viral pathogens and may play a role in preventing HIV infection of CD4+ T cells.

Insulin Regulates Glycogen Synthesis in Human Endometrial Glands Through Increased GYS2

CONTEXT

Glycogen synthesis is a critical metabolic function of the endometrium to prepare for successful implantation and sustain embryo development. Yet, regulation of endometrial carbohydrate metabolism is poorly characterized. Whereas glycogen synthesis is attributed to progesterone, we previously found that the metabolic B isoform of the insulin receptor is maximally expressed in secretory-phase endometrium, indicating a potential role of insulin in glucose metabolism.

OBJECTIVE

We sought to determine whether insulin or progesterone regulates glycogen synthesis in human endometrium.

DESIGN, PARTICIPANTS, OUTCOME MEASUREMENTS

Endometrial epithelial cells were isolated from 28 healthy women and treated with insulin, medroxyprogesterone (MPA), or vehicle. Intracellular glycogen and the activation of key enzymes were quantified.

RESULTS

In epithelia, insulin induced a 4.4-fold increase in glycogen, whereas MPA did not alter glycogen content. Insulin inactivated glycogen synthase (GS) kinase 3α/β (GSK3α/β), relieving inhibition of GS. In a regulatory mechanism, distinct from liver and muscle, insulin also increased GS by 3.7-fold through increased GS 2 (GYS2) gene expression.

CONCLUSIONS

We demonstrate that insulin, not progesterone, directly regulates glycogen synthesis through canonical acute inactivation of GSK3α/β and noncanonical stimulation of GYS2 transcription. Persistently elevated GS enables endometrium to synthesize glycogen constitutively, independent of short-term nutrient flux, during implantation and early pregnancy. This suggests that insulin plays a key, physiological role in endometrial glucose metabolism and underlines the need to delineate the effect of maternal obesity and hyperinsulinemia on fertility and fetal development.

Regulation of inflammatory mediator expression in bovine endometrial cells: effects of lipopolysaccharide, interleukin 1 beta, and tumor necrosis factor alpha

An abnormal uterine environment can influence maternal-fetal communication, conception rate and disrupt normal embryo development, thereby affecting fertility and the reproductive performance of dairy cows. Animal variability means that development of endometrial cell lines with appropriate characteristic are required. We evaluated the effect of an infectious agent (i.e., bacterial lipopolysaccharide; LPS) and proinflammatory mediators (i.e., Interleukin 1 beta; IL-1β, and tumor necrosis factor alpha; TNFα) on inflammatory mediator gene expression and production by bovine endometrial epithelial (bEEL) and stromal (bCSC) cell lines. Expression of CXCL8/IL8, IL1A, IL1B, and IL6 cytokine genes was significantly upregulated in both epithelial and stromal cells when treated with LPS and IL-1β. LPS treatment of epithelial cells (compared with treatment by IL-1β and TNFα) exhibited greater CXCL8/IL8, IL1A, IL1B, and IL6 cytokine gene expression. Whereas, in stromal cells, IL-1β treatment (compared with LPS and TNFα) exhibited greater CXCL8/IL8, IL1A, IL1B, and IL6 cytokine gene expression. Interestingly, bEEL and bCSC cells treated with IL-1β increased IL1B gene expression, suggesting that IL-1β may act unusually in an autocrine-positive feedback loop. Cytokine production was stimulated by these agents in both cell types. We suggest that the characteristics of these two cell lines make them excellent tools for the study of intrauterine environment.

Endometrial apoptosis and neutrophil infiltration during menstruation exhibits spatial and temporal dynamics that are recapitulated in a mouse model

Menstruation is characterised by synchronous shedding and restoration of tissue integrity. An in vivo model of menstruation is required to investigate mechanisms responsible for regulation of menstrual physiology and to investigate common pathologies such as heavy menstrual bleeding (HMB). We hypothesised that our mouse model of simulated menstruation would recapitulate the spatial and temporal changes in the inflammatory microenvironment of human menses. Three regulatory events were investigated: cell death (apoptosis), neutrophil influx and cytokine/chemokine expression. Well-characterised endometrial tissues from women were compared with uteri from a mouse model (tissue recovered 0, 4, 8, 24 and 48 h after removal of a progesterone-secreting pellet). Immunohistochemistry for cleaved caspase-3 (CC3) revealed significantly increased staining in human endometrium from late secretory and menstrual phases. In mice, CC3 was significantly increased at 8 and 24 h post-progesterone-withdrawal. Elastase+ human neutrophils were maximal during menstruation; Ly6G+ mouse neutrophils were maximal at 24 h. Human endometrial and mouse uterine cytokine/chemokine mRNA concentrations were significantly increased during menstrual phase and 24 h post-progesterone-withdrawal respectively. Data from dated human samples revealed time-dependent changes in endometrial apoptosis preceding neutrophil influx and cytokine/chemokine induction during active menstruation. These dynamic changes were recapitulated in the mouse model of menstruation, validating its use in menstrual research.

p38 Mitogen-Activated Protein Kinase is Involved in the Pathogenesis of Endometriosis by Modulating Inflammation, but not Cell Survival

BACKGROUND

Local pro-inflammatory environment and enhanced cell survival contribute to the endometriosis development. A serine/threonine kinase p38 mitogen-activated protein kinase (MAPK) mediates intracellular signaling of cytokine production, cell proliferation, and apoptosis in different cell types. The current study compares p38 MAPK activity in normal endometrium and endometriosis, and assesses role(s) of p38 MAPK on cytokine production and cell survival in endometriosis.

METHODS

Immunohistochemical levels of total and phosphorylated (active) p38 MAPK as well as its correlation with interleukin 8 (IL-8) expression, and cell proliferation and apoptosis were compared in normal human endometrium and endometriosis. The action of p38 MAPK on pro-inflammatory cytokine-induced IL-8 and monocyte chemotactic protein (MCP)-1 expression in endometriotic cells were assessed by enzyme-linked immunosorbent assay. The 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide cell survival, 5-bromo-2'-deoxyuridine incorporation, and Terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick end labeling assays were used to determine the function of p38 MAPK in cultured human endometriotic stromal cell proliferation and apoptosis.

RESULTS

p38 MAPK activity was significantly higher in both eutopic and ectopic endometria compared to normal endometria during late proliferative and early secretory phases ( P < .05). Increased p38 MAPK activity in endometriotic cells correlated with IL-8 expression (Pearson correlation coefficient r = 0.83, P < .01), but not with apoptosis in vivo. The pro-inflammatory cytokines IL-1β and tumor necrosis factor (TNF)-α induced activation of p38 MAPK. Inhibition of p38 MAPK activity blocked IL-1β and TNF-α-induced IL-8 and MCP-1 secretion in cultured endometriotic stromal cells ( P < .05), but did not impact on endometriotic cell survival.

CONCLUSIONS

These results suggest that rather than modulating cell survival, increased p38 MAPK activity in endometriotic cells contributes to the pathogenesis of endometriosis by promoting the local inflammatory milieu.

Increased expression of integrin-linked kinase during decidualization regulates the morphological transformation of endometrial stromal cells

OBJECTIVE

To study the impact of integrin-linked kinase (ILK) in endometrial stromal cells (ESCs) during decidualization.

DESIGN

Laboratory study with the use of human endometrium.

SETTING

University hospital.

PATIENT(S)

Fertile reproductive-age women who had not received hormonal treatment for 3 months before tissue collection.

INTERVENTION(S)

Endometrium tissue collection, in vitro decidualization of isolated ESCs, and small interfering (si) RNA transfection.

MAIN OUTCOME MEASURE(S)

Immunohistochemistry, ELISA, Western blot analysis, methylthiazolyl tetrazolium assay, and immunofluorescence staining.

RESULT(S)

In vivo expression of ILK is significantly increased in distended-fusiform stromal cells of late secretory endometrium and in cobblestone-shaped decidual cells of early pregnancy. During in vitro decidualization for up to 8 days, confluent cultures of isolated ESCs consistently displayed increased ILK expression and morphologic transformation from fibroblast-like to polygonal cells. Subsequent ILK knockdown by siRNA transfection reversed this transformation, accompanied by decreased phosphorylation of glycogen synthase kinase (GSK) 3β and decreased viable cell numbers. Immunofluorescence staining of the decidualized ESCs demonstrated linkage of increased levels of ILK at the tips of the fan-shaped organization of actin stress fibers located in the submembranous area, which expanded the decidual cells into a typical polygonal appearance. Knock-down of ILK abrogated the polymerization and organization of actin fibers, which reverted the cells to their undecidualized morphology.

CONCLUSION(S)

During human endometrial decidualization, ILK is essential for morphologic transformation of ESCs through organization of the actin cytoskeleton; it may also function through subsequent GSK3β signaling, which requires further studies.

Decreased Endometrial Expression of Leukemia Inhibitory Factor Receptor Disrupts the STAT3 Signaling in Adenomyosis During the Implantation Window

BACKGROUND

Adenomyosis was found to have negative impacts on embryo implantation. Leukemia inhibitory factor (LIF), proposed to be a molecular marker for endometrial receptivity, works through the LIF receptor (LIFR) on both the embryo and the endometrium. We aimed to evaluate the endometrial expression of LIF and LIFR and its subsequent signaling in patients with adenomyosis during the window of implantation (WOI).

METHODS

Endometrium was obtained during the WOI from patients with adenomyosis (age <45 years) who underwent hysterectomy and from age-matched controls who had no endometriosis or adenomyosis. The LIF and LIFR expressions were measured by polymerase chain reaction for messenger RNA expression, immunohistochemistry for protein intensity and localization, and immunofluorescent staining for colocalization. The ratio of signal transducer and activator of transcription 3 (STAT3) to extracellular signal-regulated kinase (ERK) phosphorylation was measured by Western blot of both the endometrium and the isolated human endometrial stromal cells (ESCs).

RESULTS

Patients with adenomyosis showed significantly and parallelly reduced LIF and LIFR expressions in the eutopic endometrium during WOI as compared with the control women and subsequently with remarkably reduced activation of STAT3 and ERK signaling. The significantly increased STAT3 and ERK phosphorylation induced by the LIF treatment in the cultured ESCs supported the linkage between the LIF-LIFR reaction and the signaling cascade.

CONCLUSION

Significant reduction in LIFR expression and the reduced activation of subsequent signaling strongly suggest a working model of how the implantation markers, LIF, may affect the endometrium of patients with adenomyosis. These molecular changes supported the declined implantation rates reported in patients with adenomyosis.

Differential Expression of IR-A, IR-B and IGF-1R in Endometrial Physiology and Distinct Signature in Adenocarcinoma

CONTEXT

Type 2 diabetes and obesity are risk factors for endometrial hyperplasia and cancer, suggesting that hyperinsulinemia contributes to pathogenesis. Insulin action through insulin receptor (IR) splice variants IR-A and IR-B regulates cellular mitogenesis and metabolism, respectively.

OBJECTIVE

We hypothesized that IR-A and IR-B are differentially regulated in normal endometrium, according to mitogenic and metabolic requirements through the menstrual cycle, as well as in endometrial hyperplasia and cancer.

DESIGN

IR-A, IR-B, and IGF-1 receptor (IGF-1R) mRNA was quantified in endometrium, endometrial epithelial and stromal cells, and in vitro after hormone stimulation.

SETTING

Academic center.

PATIENTS

Endometrium was collected from women with regular cycles (n = 71), complex hyperplasia (n = 5), or endometrioid adenocarcinoma (n = 11).

INTERVENTION(S)

In vitro sex-steroid treatment.

MAIN OUTCOME MEASURE(S)

IR-A and IR-B expression Results: IR-A increased dramatically during the early proliferative phase, 20-fold more than IR-B. In early secretory phase, IR-B and IGF-1R expression increased, reaching maximal expression, whereas IR-A decreased. In adenocarcinoma, IR-B and IGF-1R expression was 5- to 6-fold higher than normal endometrium, whereas IR-A expression was similar to IR-B. Receptor expression was unrelated to body mass index.

CONCLUSION

IR-A was elevated during the normal proliferative phase, and in endometrial hyperplasia and adenocarcinoma. The dramatic early rise of IR-A in normal endometrium indicates IR-A is the predominant isoform responsible for initial estrogen-independent endometrial proliferation as well as that of cancer. IR-B is elevated during the normal secretory phase when glucose uptake and glycogen synthesis support embryo development. Differing from other cancers, IR-B expression equals mitogenic IR-A in endometrial adenocarcinoma. Differential IR isoform expression suggests a distinct role for each in endometrial physiology and cancer.

Blocking CXCL9 Decreases HIV-1 Replication and Enhances the Activity of Prophylactic Antiretrovirals in Human Cervical Tissues

OBJECTIVES

The interferon-gamma-induced chemokine CXCL9 is expressed in a wide range of inflammatory conditions including those affecting the female genital tract. CXCL9 promotes immune cell recruitment, activation, and proliferation. The role of CXCL9 in modulating HIV-1 infection of cervicovaginal tissues, a main portal of viral entry, however, has not been established. We report a link between CXCL9 and HIV-1 replication in human cervical tissues and propose CXCL9 as a potential target to enhance the anti-HIV-1 activity of prophylactic antiretrovirals.

DESIGN

Using ex vivo infection of human cervical tissues as a model of mucosal HIV-1 acquisition, we described the effect of CXCL9 neutralization on HIV-1 gene expression and mucosal CD4 T-cell activation. The anti-HIV-1 activity of tenofovir, the leading mucosal pre-exposure prophylactic microbicide, alone or in combination with CXCL9 neutralization was also studied.

METHODS

HIV-1 replication was evaluated by p24 ELISA. HIV-1 DNA and RNA, and CD4, CCR5, and CD38 transcription were evaluated by quantitative real-time polymerase chain reaction. Frequency of activated cervical CD4 T cells was quantified using fluorescence-activated cell sorting.

RESULTS

Antibody blocking of CXCL9 reduced HIV-1 replication by decreasing mucosal CD4 T-cell activation. CXCL9 neutralization in combination with suboptimal concentrations of tenofovir, possibly present in the cervicovaginal tissues of women using the drug inconsistently, demonstrated an earlier and greater decrease in HIV-1 replication compared with tissues treated with tenofovir alone.

CONCLUSIONS

CXCL9 neutralization reduces HIV-1 replication and may be an effective target to enhance the efficacy of prophylactic antiretrovirals.

Possible Role of Phthalate in the Pathogenesis of Endometriosis: In Vitro, Animal, and Human Data

CONTEXT

Although phthalates were shown to have several negative effects on reproductive function in animals, its role in the pathogenesis of endometriosis remains to be elucidated.

OBJECTIVE

We aimed to investigate the in vitro and in vivo effects of di-(2-ethylhexyl)-phthalate (DEHP) and to compare the urinary levels of several phthalate metabolites between women with and without endometriosis.

DESIGN

For experimental studies, we used endometrial cell culture and nonobese diabetic/severe combined immunodeficiency (NOD/SCID) mouse models. We also performed a prospective case-control study for human sample analyses.

SETTING

The study was conducted at an academic center.

MAIN OUTCOME MEASURES

The activities of matrix metalloproteinase (MMP)-2 and 9, cellular invasiveness, phosphorylation of extracellular signal-regulated kinase (Erk), and expression of p21-activated kinase 4 were analyzed in endometrial cells treated with DEHP. The implant size was compared between NOD/SCID mice fed with and without DEHP. Urinary concentrations of several phthalate metabolites were compared between women with and without endometriosis.

RESULTS

In vitro treatment of endometrial cells with DEHP led to significant increases of MMP-2 and 9 activities, cellular invasiveness, Erk phosphorylation, and p21-activated kinase 4 expression. The size of the endometrial implant was significantly larger in the NOD/SCID mice fed with DEHP compared with those fed with vehicle. The urinary concentration of mono (2-ethyl-5-hydroxyhexyl) phthalate, mono (2-ethyl-5-oxohexyl) phthalate, and mono (2-ethyl-5-carboxyphentyl) phthalate were significantly higher in women with endometriosis compared with controls.

CONCLUSION

These findings strongly suggest that exposure to phthalate may lead to establishment of endometriosis by enhancing invasive and proliferative activities of endometrial cells.

Di-(2-ethylhexyl)-phthalate induces oxidative stress in human endometrial stromal cells in vitro

Di-(2-ethylhexyl)-phthalate (DEHP) accumulates in the environment, and its exposure is possibly associated with endocrine-related disease in women of reproductive age. The effects of DEHP on human endometrial cells are unknown. We treated human endometrial stromal cells with 10, 100, and 1000 pmol of DEHP and measured reactive oxygen species (ROS) generation, expression levels of antioxidant enzymes, alteration of MAPK/NF-κB signaling and hormonal receptors. DEHP increased reactive oxygen species (ROS) generation and decreased expression of superoxide dismutase (SOD), glutathione peroxidase (GPX), heme oxygenase (HO), and catalase (CAT). By DEHP exposure, p-ERK/p-p38 and NF-κB mediated transcription was increased. Additionally, DEHP induced estrogen receptor-α (ER-α) expression in a dose-dependent manner. This study shows the need for future mechanistic studies of oxidative stress, MAPK/NF-κB signaling, and ER-α as molecular mediators of DEHP-associated endometrial stromal cell alterations, which may be associated with the development of endocrine-related disease such as endometriosis.

The role of sex hormones in immune protection of the female reproductive tract

Within the human female reproductive tract (FRT), the challenge of protection against sexually transmitted infections (STIs) is coupled with the need to enable successful reproduction. Oestradiol and progesterone, which are secreted during the menstrual cycle, affect epithelial cells, fibroblasts and immune cells in the FRT to modify their functions and hence the individual's susceptibility to STIs in ways that are unique to specific sites in the FRT. The innate and adaptive immune systems are under hormonal control, and immune protection in the FRT varies with the phase of the menstrual cycle. Immune protection is dampened during the secretory phase of the cycle to optimize conditions for fertilization and pregnancy, which creates a 'window of vulnerability' during which potential pathogens can enter and infect the FRT.

A potential novel treatment strategy: inhibition of angiogenesis and inflammation by resveratrol for regression of endometriosis in an experimental rat model

The aim of our study was to evaluate the effectiveness of resveratrol in experimentally induced endometrial implants in rats through inhibiting angiogenesis and inflammation. Endometrial implants were surgically induced in 24 female Wistar-Albino rats in the first surgery. After confirmation of endometriotic foci in the second surgery, the rats were divided into resveratrol (seven rats), leuprolide acetate (eight rats), and control (seven rats) groups and medicated for 21 d. In the third surgery, the measurements of mean areas and histopathological analysis of endometriotic lesions, VEGF, and MCP-1 measurements in blood and peritoneal fluid samples, and immunohistochemical staining were evaluated. After treatment, significant reductions in mean areas of implants (p < 0.01) and decreased mean histopathological scores of the implants (p < 0.05), mean VEGF-staining scores of endometriotic implants (p = 0.01), and peritoneal fluid levels of VEGF and MCP-1 (p < 0.01, for VEGF and p < 0.01, for MCP-1) were found in the resveratrol and leuprolide acetate groups. Serum VEGF (p = 0.05) and MCP-1 (p = 0.01) levels after treatment were also significantly lower in the resveratrol and leuprolide acetate groups. Resveratrol appears to be a potential novel therapeutic agent in the treatment of endometriosis through inhibiting angiogenesis and inflammation. Further studies are needed to determine the optimum effective dose in humans and to evaluate other effects on reproductive physiology.

Increased expression of p21-activated kinase 4 in adenomyosis and its regulation of matrix metalloproteinase-2 and -9 in endometrial cells

OBJECTIVE

To investigate the expression of p21-activated kinase 4 (Pak4) in both adenomyotic foci and the eutopic endometrium of women with adenomyosis, and whether the activities of matrix metalloproteinases (MMPs)-2 and -9 are regulated by Pak4 in endometrial cells.

DESIGN

Experimental study using human samples and cell lines.

SETTING

University hospital.

PATIENT(S)

Thirty-nine patients with histologic evidence of adenomyosis, and 34 patients with carcinoma in situ of the uterine cervix without adenomyosis or endometriosis.

INTERVENTION(S)

Immunohistochemistry, zymography after transfection with Pak4 small interfering RNA (siRNA), and western blot analyses after nuclear factor kappa-B (NF-кB) inhibitor treatment.

MAIN OUTCOME MEASURE(S)

The Pak4 immunoreactivity of women with vs. without adenomyosis was compared semiquantitatively. The activities of MMP-2 and -9 were analyzed in eutopic endometrial stromal cells and Ishikawa cells after transfection with Pak4 siRNA. The Pak4 expression was evaluated in endometrial cells after treatment with NF-кB inhibitor.

RESULT(S)

Pak4 immunoreactivity was increased in adenomyotic foci and in the eutopic endometrium of women with adenomyosis. Transfection of endometrial cells with Pak4 siRNA led to significant decreases of MMP-2 and -9 activities. In vitro treatment of endometrial cells with tumor necrosis factor-alpha caused a significant increase of NF-кB activation and Pak4 expression, which was obviously decreased by the NF-кB inhibitor pyrrolidinedithiocarbamate.

CONCLUSION(S)

Our results suggest that Pak4 is regulated by NF-кB and that increased Pak4 expression can lead to development of adenomyosis by enhancing the invasiveness of endometrial cells through regulation of MMP-2 and -9 activities.

Molecular evolution, characterization and expression profiling of uterine aldoketoreductase 1B5 gene in endometrium of goat (Capra hircus)

Aldoketoreductase 1B5 (AKR1B5), a member of the Aldoketoreductase family, is involved in the production of Prostaglandin F2α (PGF2α) as one of vital prostaglandin F synthase (PGFS). PGs (Prostaglandins) play a crucial role in female reproductive system. In the present study, we cloned and characterized the full-length open reading frame of AKR1B5 gene in Black Bengal (BB) goat. The complete coding sequence of AKR1B5 comprises an entire open reading frame of 951 bp, encoding 316 amino acid (AA) residues. BB AKR1B5 showed >82.9% identity with that of cattle, rabbit, human, and rat at nucleotide and amino acid levels, respectively. Further, a systematic study of AKR1B5 sequence evolution was also conducted using Phylogenetic Analysis by Maximum Likelihood (PAML), entropy plot, and Blossum 62 in a phylogenetic context. Analysis of nonsynonymous to synonymous nucleotide substitution rate ratios (Ka/Ks) revealed that negative selection may have been operating on this gene during evolution in goat, cattle, rabbit, human, and rat, which showed its conservation across species. Further, expression of AKR1B5 was determined by quantitative real-time PCR in goat endometrial tissues at different stages of the estrous cycle and early pregnancy. Our results indicated its high expression at luteolytic phase (stage III; day 16-21) during the estrous cycle. However, during early (day ∼30-40) pregnancy the expression was highest as compared to estrous cycle.

Increased nuclear expression of nuclear factor kappa-B p65 subunit in the eutopic endometrium and ovarian endometrioma of women with advanced stage endometriosis

PROBLEM

We evaluated whether the expression of NF-кB p65 subunit is increased in the eutopic endometrium and/or in the ovarian endometrioma of women with advanced stage endometriosis, and ascertained in vitro effects of proinflammatory cytokines on the expression and DNA binding of NF-кB p65 subunit in endometrial cells.

METHOD OF STUDY

Immunohistochemistry was performed to compare the nuclear NF-кB p65 subunit immunoreactivity between women with and without advanced stage endometriosis. The nuclear NF-кB p65 subunit expression and DNA binding were also analyzed in endometrial cells treated with tumor necrosis factor-alpha (TNF-α) or interleukin-1beta (IL-1β) utilizing Western blot analysis, enzyme-linked immunosorbent assay, and electrophoretic mobility shift assay.

RESULTS

The immunoreactivity of the nuclear NF-кB p65 subunit was significantly increased in the eutopic endometrium as well as in the ovarian endometrioma of women with endometriosis compared with the controls. In vitro treatment of endometrial cells with TNF-α and IL-1β led to a significant increase in nuclear NF-кB p65 subunit expression and DNA binding.

CONCLUSIONS

The nuclear expression of NF-κB p65 is increased in the eutopic endometrium and ovarian endometrioma of women with advanced stage endometriosis, which strongly suggests that NF-кB signaling plays a crucial role in the pathogenesis and/or pathophysiology of endometriosis.

Molecular basis of implantation

The process of embryonic implantation needs coordinated development and communication between the blastocyst and the maternal endometrium. Considerable advances in the understanding of the cell biology of the human embryo and maternal endometrium have been achieved separately. However, the communication between them, and the reciprocal effects on each other, constitute a complicated and yet unsolved question in reproductive medicine that must be further investigated. A paracrine dialogue between the embryo, endometrium and the corpus luteum is known to occur in other species such as rodents and primates. The aim of this work is to present updated information on the embryonic regulation of endometrial epithelial molecules such as adhesion molecules, anti-adhesion molecules, cytoskeletal proteins, chemokines and leptin during the apposition and adhesion phases of human implantation.

Effects of simvastatin on retinoic acid system in primary human endometrial stromal cells and in a chimeric model of human endometriosis

CONTEXT

Retinoic acid (RA) may promote survival or apoptosis of cells, depending on the levels of binding proteins: apoptosis-inducing cellular RA binding protein 2 (CRABP2), and cell survival-promoting fatty acid binding protein 5 (FABP5). Increased cellular uptake of retinol and altered actions of RA related to reduced expression of CRABP2 may contribute to the development of endometriosis. Recently statins have been shown to inhibit growth of human endometrial stromal (HES) cells and to reduce the number and size of endometriotic implants in experimental models of this disorder.

OBJECTIVE

The objective of the study was to determine whether effects of simvastatin on HES cells and experimental endometriotic implants are related to the modulation of the RA system.

METHODS

Effects of simvastatin and RA on proliferation and apoptosis of HES cells were evaluated. Expression of stimulated by RA 6 (STRA6), CRABP2, and FABP5 was determined by real-time PCR and Western blotting. Effects of simvastatin were also evaluated in a nude mouse model of human endometriosis.

RESULTS

Simvastatin potentiated an inhibitory effect of RA on growth of HES cells. In HES cells, simvastatin induced expression of STRA6 and CRABP2 but not FABP5. Similarly, simvastatin treatment of nude mice bearing human endometrial xenografts led to an increased expression of CRABP2 and STRA6 proteins in ectopic lesions.

CONCLUSIONS

Simvastatin interacts with the RA system, inducing the expression of the key protein regulating the uptake of retinol (STRA6) and the expression of apoptosis-promoting CRABP2. These effects may contribute to cooperative apoptosis-inducing effects of simvastatin and RA and support the examination of these compounds in the treatment of endometriosis.

Simvastatin decreases invasiveness of human endometrial stromal cells

Recently we reported that statins, the competitive inhibitors of the key enzyme regulating the mevalonate pathway, 3-hydroxy-3-methylglutaryl-coenzyme A reductase (HMGCR), decrease proliferation of human endometrial stromal (HES) cells. Furthermore, we found that simvastatin treatment reduces the number and the size of endometrial implants in a nude mouse model of endometriosis. The present study was undertaken to investigate the effect of simvastatin on HES cell invasiveness and on expression of selected genes relevant to invasiveness: matrix metalloproteinase 2 (MMP2), MMP3, tissue inhibitor of matrix metalloproteinase 2 (TIMP2), and CD44. Because statin-induced inhibition of HMGCR reduces the production of substrates for isoprenylation-geranylgeranyl pyrophosphate (GGPP) and farnesyl pyrophosphate (FPP)-the effects of GGPP and FPP were also evaluated. Simvastatin induced a concentration-dependent reduction of invasiveness of HES cells. This effect of simvastatin was abrogated by GGPP but not by FPP. Simvastatin also reduced the mRNA levels of MMP2, MMP3, and CD44, but increased TIMP2 mRNA; all these effects of simvastatin were partly or entirely reversed in the presence of GGPP. The present findings provide a novel mechanism of action of simvastatin on endometrial stroma that may explain reduction of endometriosis in animal models of this disease. Furthermore, the presently described effects of simvastatin are likely mediated, at least in part, by inhibition of geranylgeranylation.

CXCL8 enhances proliferation and growth and reduces apoptosis in endometrial stromal cells in an autocrine manner via a CXCR1-triggered PTEN/AKT signal pathway

BACKGROUND

Chemokine CXCL8 (also known as IL-8) has been identified as a potential regulator of endometrial stromal cells (ESCs), but it is unclear how CXCL8 regulates the survival of ESCs in the pathogenesis of endometriosis.

METHODS

We assessed the secretion of CXCL8 by enzyme-linked immunosorbent assays and the expression of its receptors, CXCR1 and CXCR2, by in-cell Western assay and immunohistochemistry. The effects of CXCL8 on the activation or expression of various cell mediators were also investigated by in-cell Western assay. The effects of CXCL8 on the proliferation, growth and apoptosis of ESCs in vitro were assessed by BrdU assays, cell counts and annexin V labeling, respectively.

RESULTS

Secretion of CXCL8 and expression of CXCR1 in the eutopic ESCs from women with endometriosis were significantly higher than that in control ESCs, but the expression of CXCR2 showed no significant difference between these two cell types. CXCL8 stimulated proliferation and growth and reduced apoptosis of ESCs in an autocrine manner, and these effects were abolished by anti-human CXCL8 and CXCR1 neutralizing antibodies and by a PI3K/Akt inhibitor. Moreover, CXCL8 up-regulated the expression of the anti-apoptotic proteins, survivin and Bcl-2, inhibited the expression of the Phosphatase and tensin homolog (PTEN) and activated the phosphorylation of Akt.

CONCLUSIONS

This study suggests that CXCL8 and CXCR1 are involved in the pathogenesis of endometriosis by up-regulating proliferation and growth and restricting apoptosis in ESCs by activating the PTEN/Akt pathway and mediating the expression of survivin and Bcl-2.

Statins inhibit monocyte chemotactic protein 1 expression in endometriosis

Statins are potent inhibitors of the endogenous mevalonate pathway. Besides inhibiting cholesterol biosynthesis, statins may also demonstrate anti-inflammatory properties. Inflammation is implicated in the attachment and invasion of endometrial cells to the peritoneal surface and growth of ectopic endometrium by inducing proliferation and angiogenesis. In this study, the effect of statins on monocyte chemotactic protein 1 (MCP-1) expression in endometriotic implants in nude mouse model and in cultured endometriotic cells was evaluated. In mouse model, simvastatin decreased MCP-1 expression in a dose-dependent manner in endometriotic implants (P < .05). Similarly, both simvastatin and mevastatin revealed a dose-dependent inhibition of MCP-1 production in cultured endometriotic cells (P < .01). This inhibitory effect of the statins on MCP-1 production was reversed by the downstream substrates of the mevalonate pathway. Moreover, statins decreased MCP-1 messenger RNA expression in cultured endometriotic cells (P < .05). In conclusion, statins exert anti-inflammatory effect in endometriotic cells and could provide a potential treatment of endometriosis in the future.

Keratinocyte Growth Factor Stimulates Macrophage Inflammatory Protein 3α and Keratinocyte-derived Chemokine Secretion by Mouse Uterine Epithelial Cells

PROBLEM

communication between uterine epithelial cells and the underlying stromal fibroblasts is critical for proper endometrial function. Stromal fibroblast-derived growth factors have been shown to regulate epithelial immune functions. The purpose of this study was to determine whether keratinocyte growth factor (KGF) regulates uterine epithelial cell chemokine and antimicrobial secretion.

METHOD OF STUDY

uterine epithelial cells were isolated from Balb/c mice and cultured in either 96-well plates or transwell inserts. Epithelial cells were treated with KGF, epidermal growth factor (EGF), or hepatocyte growth factor (HGF). Macrophage inflammatory protein 3α (MIP3α) and keratinocyte-derived chemokine (KC) levels were measured by ELISA.

RESULTS

keratinocyte growth factor stimulated the secretion of MIP3α and KC. The effects on MIP3α by KGF were specific because EGF and HGF had no effect. In contrast, KGF, EGF, and HGF had similar effects on KC. Furthermore, KGF administered to the apical side of epithelial cells had no effect on MIP3α or KC secretion, indicating that the KGF receptor is located on the basolateral surface of uterine epithelial cells.

CONCLUSION

we demonstrate that KGF plays a role in uterine epithelial cell secretion of MIP3α and KC, key immune mediators involved in the protection of mucosal surfaces in the female reproductive tract.

Bidirectional interaction between unfolded-protein-response key protein HSPA5 and estrogen signaling in human endometrium

The human endometrium is a dynamic tissue that undergoes cyclic changes under the influence of steroid hormones as well as numerous local paracrine and autocrine factors. Heat shock 70 kDa protein (HSPA5; also known as GRP78/BiP), a molecular chaperone within the endoplasmic reticulum, plays crucial roles in normal cellular processes as well as in stress conditions, in which it is a central regulator for the unfolded protein response (UPR). We hypothesized that HSPA5 expression level is variable throughout the menstrual cycle in human endometrium and that estrogen signaling cross-talks with UPR signaling by interacting with HSPA5. HSPA5 expression throughout the menstrual cycle was evaluated in vivo in normal human endometrium. Using in vitro techniques, we then assessed the bidirectional regulation of HSPA5 and estrogen signaling in human endometrial glandular (Ishikawa) and stromal cells (ESC). HSPA5 immunoreactivity in endometrial glandular and stromal cells was cycle-dependent, and was significantly higher in phases of the menstrual cycle when estradiol (E(2)) levels are known to be the lowest compared with the rest of the cycle (P < 0.001). E(2) did not affect HSPA5 expression after 8-24 h incubation in Ishikawa cells and ESC in vitro. However, tunicamycin-induced HSPA5 expression was significantly lowered in these cells when pretreated with E(2) (P < 0.01 and P < 0.05, respectively). On the other hand, tunicamycin decreased E(2) up-regulated alkaline phosphatase activity (P < 0.001). In conclusion, there is cycle-dependent HSPA5 expression with a possible inverse correlation between HSPA5 expression and E(2) levels in human endometrium. We suggest that estrogen signaling cross-talks with the UPR cascade by interacting with HSPA5, as supported by our in vitro findings.

The mRNA-binding protein HuR is regulated in the menstrual cycle and repressed in ectopic endometrium

Cytokines modulate turnover of the endometrium during the menstrual cycle and contribute to the pathogenesis of endometriosis. Gene expression for cytokines is often regulated by proteins that bind to adenosine- and uridine-rich elements (AREs) in their transcripts to stabilize or destabilize bound messenger RNAs (mRNAs). HuR/ELAVL1 is an RNA-binding protein that stabilizes ARE-containing mRNAs. We hypothesized that HuR might play a role in regulating cytokine expression during the menstrual cycle and in endometriosis and characterized the expression and regulation of HuR in eutopic and ectopic human endometrium. Tissue sections obtained from normal (n = 23) and ectopic (n = 16) endometrium were immunostained for HuR, and staining intensity was evaluated by HSCORE. Cultured stromal cells isolated from normal endometrium were treated with vehicle, estradiol (E2), progesterone (P), E2 + P, tumor necrosis factor-α (TNF-α), and interleukin 1β (IL-1β) for 24 hours, and HuR expression was determined by Western blot. HuR immunoreactivity was significantly lower in the early proliferative and late secretory phases (157.5 ± 11.08 and 190.0 ± 15.2, respectively), compared to the mid-late proliferative (270.0 ± 8.0) and early-mid secretory phases (256.6 ± 20.2; P < .01, analysis of variance [ANOVA]). Furthermore, HuR expression was significantly lower in ectopic endometrial cells compared to normal endometrium in mid-late proliferative and early-mid-secretory phases (P < .01). Estrogen, P, or cytokines did not alter HuR expression in cultured endometrial stromal cells. Increased HuR levels in the mid-menstrual phases are likely to contribute to reduced mid-cycle cytokine expression and enhanced cellular survival in eutopic endometrium. In ectopic endometrium, elevated cytokine levels associated with endometriosis likely reduce HuR expression.

Resveratrol inhibits development of experimental endometriosis in vivo and reduces endometrial stromal cell invasiveness in vitro

Endometriosis is a common gynecologic disorder characterized by ectopic attachment and growth of endometrial tissues. Resveratrol is a natural polyphenol with antiproliferative and anti-inflammatory properties. Our objective was to study the effects of resveratrol on human endometriotic implants in a nude mouse model and to examine its impact on human endometrial stromal (HES) cell invasiveness in vitro. Human endometrial tissues were obtained from healthy donors. Endometriosis was established in oophorectomized nude mice by intraperitoneal injection of endometrial tissues. Mice were treated with 17β-estradiol (8 mg, silastic capsule implants) alone (n = 16) or with resveratrol (6 mg/mouse; n = 20) for 10-12 and 18-20 days beginning 1 day after tissue injection. Mice were killed and endometrial implants were evaluated. A Matrigel invasion assay was used to examine the effects of resveratrol on HES cells. We assessed number and size of endometriotic implants in vivo and Matrigel invasion in vitro. Resveratrol decreased the number of endometrial implants per mouse by 60% (P < 0.001) and the total volume of lesions per mouse by 80% (P < 0.001). Resveratrol (10-30 μM) also induced a concentration-dependent reduction of invasiveness of HES by up to 78% (P < 0.0001). Resveratrol inhibits development of endometriosis in the nude mouse and reduces invasiveness of HES cells. These observations may aid in the development of novel treatments of endometriosis.

Expression and role of interleukin-23 in human endometrium throughout the menstrual cycle and early pregnancy

Interleukin-23 (IL-23) is a novel cytokine involved in the regulation of organ-specific immune responses. We hypothesized that expression of IL-23 in the human endometrium is menstrual cycle and pregnancy dependent, and is involved in endometrial immune regulation. IL-23 expression and regulation was investigated in the human endometrium and placenta in vivo using immunohistochemistry and in vitro using Western blot and cell viability analyses. IL-23 immunoreactivity in endometrial glandular cells was highest in the late proliferative and early secretory phases, as compared to other cycle phases and first trimester tissues. Endometrial stromal cells (ESC) showed weak IL-23 immunoreactivity without significant changes in intensity and distribution throughout the menstrual cycle. First trimester decidual cells revealed significantly stronger IL-23 staining compared to ESC from non-pregnant endometrium. Both villous cytotrophoblasts and syncytiotrophoblasts also showed positive IL-23 immunoreactivity, with a higher staining in syncytiotrophoblasts. In the trophoblastic cell line HRT8, IL-23 expression increased in a time-dependent manner, but was undetectable in stromal cells under all treatment conditions. ESC treated with recombinant IL-23 showed significantly decreased IL-8 secretion and cell viability. These results suggest a possible regulatory role for IL-23 in the menstrual cycle and in early pregnancy, although the extent and function of this role are yet to be determined.

Reciprocal communication between endometrial stromal cells and macrophages

This study tested the hypothesis that reciprocal communication occurs between macrophages and cultured human endometrial stromal cells and that this communication may contribute to the pathology of endometriosis. An endometrial stromal cell line (telomerase-immortalized human endometrial stromal cell [T-HESC]) was treated with macrophage-conditioned medium (CM) +/- estradiol + progesterone. Macrophages were treated without or with T-HESC CM. DNA microarray identified 716 differentially expressed genes in T-HESCs in response to factors secreted by macrophages. Upregulated genes in T-HESC included interleukin 8 (IL-8)/chemokine (C-X-C motif) ligand 8 (CXCL8), matrix metalloproteinase 3 (MMP3), phospholamban, cysteine-rich angiogenic inducer 61 (CYR61), connective tissue growth factor (CTGF), tenascin C, and nicotinamide N-methyltransferase (NNMT), whereas integrin alpha-6 was downregulated. In contrast, 15 named genes were differentially expressed in macrophages in response to factors secreted by endometrial stromal cells. The data document reciprocal communication between macrophages and endometrial stromal cells and suggest that interaction with macrophages stimulates the expression of genes in endometrial stromal cells that may support the establishment of endometriosis.

Simvastatin induces apoptosis and alters cytoskeleton in endometrial stromal cells

CONTEXT

Statins are competitive inhibitors of 3-hydroxy-3methylglutaryl-coenzyme A reductase, with antimitotic, antioxidant, antiinflammatory, and immunomodulatory properties. Recent studies have shown that statins reduce the growth of human endometrial stromal (HES) cells and protect from the development of endometriosis in animal models.

OBJECTIVES

The present study was conducted to evaluate the effects of simvastatin on apoptosis and cytoskeleton of HES cells.

DESIGN AND SETTING

In vitro experiments were performed in the university research laboratory.

PATIENTS

HES cells were obtained from endometrial biopsies collected from nine subjects in the proliferative phase of their menstrual cycle.

MAIN OUTCOME MEASURES

The effect of simvastatin (10 and 30 mum) and/or geranylgeranyl pyrophosphate (GGPP, 30 mum) on caspase 3 and 7 activity, DNA fragmentation, and HES cell morphology was evaluated.

RESULTS

Simvastatin induced significant time- and concentration-dependent apoptotic effects on HES cells as determined by increased activity of executioner caspases and DNA fragmentation. Simvastatin also caused profound alterations in HES cell morphology and F-actin cytoskeleton. This effect was abrogated by geranylgeranyl pyrophosphate, an important product of the mevalonate pathway.

CONCLUSIONS

Simvastatin induces apoptosis and disruption of the cytoskeleton of HES cells by reducing isoprenylation in cultures of human endometrial stroma. The present findings may lead to the development of novel treatments for endometriosis involving statins.

Dose-response effect of interleukin (IL)-1β, tumour necrosis factor (TNF)-α, and interferon-γ on the in vitro production of epithelial neutrophil activating peptide-78 (ENA-78), IL-8, and IL-6 by human endometrial stromal cells

PURPOSE

The production of epithelial neutrophil activating peptide-78 (NA-78) and the interleukins IL-8 and IL-6 by endometrial stromal cells is stimulated by pro-inflammatory interleukin-1 (IL-1) and tumour necrosis factor-α (TNF-α). IL-8 is suggested to play a role in the pathogenesis of endometriosis, and in these women the peritoneal fluid concentrations of ENA-78 and IL-8 are increased. TNF-α has been tested together with interferon-γ because of their cooperative stimulation of IL-6. The release of IL-8, however, is inhibited with increasing interferon levels. The aim of the study was the analysis of the production of ENA-78, IL-6 and IL-8 by cultured human endometrial stromal cells in the presence of varying concentrations of IL-1β, TNF-α, and interferon-γ.

METHODS

Eutopic endometrial tissue was obtained from seven cycling, endometriosis-free women undergoing laparoscopy for reasons of infertility or pain. The release of ENA-78, IL-8 and IL-6 by the isolated and monolayer cultured stromal cell fraction in the presence of IL-1β (0.08 to 50 ng/mL), TNF-α, and interferon-γ (both 20 to 500 ng/mL) was determined.

RESULTS

IL-1β stimulated the production of IL-8, IL-6, and ENA-78 dose dependently from 0.08 to 2.0 ng/mL (ENA-78) or to 10 ng/mL (IL-8, IL-6); at 50 ng/mL a decrease in release was observed for IL-8 and IL-6. TNF-α stimulation yielded a plateau between 20 and 100 ng/mL. Interferon-γ stimulated IL-6 and inhibited IL-8 production above 20 ng/mL. ENA-78 release was largely unaffected by interferon-γ.

CONCLUSIONS

IL-1β and TNF-α stimulate stromal cytokine production cumulatively with different dose-response curves. The presence of interferon-γ has opposite effects on IL-8 and IL-6. TNF-α and interferon-γ should be investigated separately in future in vitro studies with endometrial cells and explants.

Increased expression of glutathione by estradiol, tumor necrosis factor-alpha, and interleukin 1-beta in endometrial stromal cells

PROBLEM

The intracellular antioxidant system, based on glutathione (GSH), plays a key role in endometrial detoxification reactions and has been proposed to be involved in the pathogenesis endometriosis. This study was designed to evaluate whether estradiol (E(2)) and proinflammatory cytokines have any effects on expression of glutathione in endometrial stromal cells (ESCs).

METHOD OF STUDY

Glutathione levels were measured utilizing high-performance liquid chromatography following in vitro culture and treatment of ESCs with estradiol, tumor necrosis factor-alpha (TNF-alpha) and interleukin 1-beta (IL-1beta).

RESULTS

The GSH level in E(2) (10(-8) m) treatment group was significantly higher than in the control group at 48 h (P < 0.05). In vitro treatment of ESCs with TNF-alpha 10 ng/mL as well as E(2) (10(-8) m) plus TNF-alpha 10 ng/mL for 48 hr also led to a significant increase in GSH level (P < 0.05; P < 0.05, respectively). Both IL-1beta 10 ng/mL and E(2) (10(-8) m) plus IL-1beta 10 ng/mL for 48 hr increased GSH level significantly (P < 0.05; P < 0.05, respectively) as well.

CONCLUSIONS

These findings might suggest that increased production of estradiol and proinflammatory cytokines in the peritoneal cavity possibly leads to the establishment of endometriosis through increased level of GSH.

Differential regulation of Akt phosphorylation in endometriosis

Protein kinase B (PKB/Akt), a serine/threonine kinase, regulates the function of many cellular proteins involved in apoptosis and proliferation. It was postulated that there is a higher Akt activity in endometriosis compared with normal endometrium, and that oestrogen may be one of the factors responsible for the high Akt activation in endometriotic cells. Phospho-Akt (pAkt) concentrations in normal, eutopic and ectopic endometrial tissues were compared by immunohistochemistry, and a higher pAkt immunoreactivity was revealed in eutopic and ectopic endometrium compared with normal endometrium, in vivo. Higher Akt phosphorylation in stromal cells from eutopic endometrium was observed, when compared with normal, in vitro (P < 0.05). Akt phosphorylation was rapidly (2-10 min) stimulated when endometrial stromal cells from normal and endometriosis patients were treated with 17 beta-oestradiol. In endometrial stromal cells from the endometriosis group, ICI 182,780 (ICI, a specific oestrogen receptor antagonist) failed to antagonize the effect of oestradiol when combined with oestradiol, and revealed a stimulatory effect on Akt phosphorylation when given alone (P < 0.05). In conclusion, since Akt affects cell survival, it is suggested that increased Akt phosphorylation may be related to the altered apoptosis/proliferation harmony in endometriosis, and therefore Akt may play a critical role in the pathogenesis of endometriosis.

Interleukin-8 (CXCL8) stimulates trophoblast cell migration and invasion by increasing levels of matrix metalloproteinase (MMP)2 and MMP9 and integrins alpha5 and beta1

Interleukin-8 (IL8/CXCL8) is present in decidua and trophoblast, which also expresses the IL8 receptors, CXCR1 and CXCR2. IL8 was shown to stimulate trophoblast migration. Matrix metalloproteinase (MMP)2, MMP9, and integrins alpha(5)beta(1) and alpha(1)beta(1) were found to play important roles in trophoblast invasion. We hypothesized that IL8 would increase this cell migration and invasion by HTR-8/SVneo cells through the activity of MMPs and integrins. Isolated first trimester of pregnancy cytotrophoblast (CT) and HTR-8/SVneo cell line were used. Migration was studied by monolayer wounding test, and invasion by Matrigel invasion test. The effects of IL8 on MMPs and integrin subunit expression were determined in HTR-8/SVneo cells by gelatin zymography and western blot respectively. The results that were obtained showed that exogenous IL8 stimulated HTR-8/SVneo cell migration and invasion. MMP2 and MMP9 levels were stimulated to 182% (P<0.01) and 134% (P<0.01) respectively. Integrin alpha(5) expression was increased to 119% (P<0.05) and integrin beta(1) expression to 173% (P<0.001) of the control values. The data that were obtained show for the first time the sensitivity of the HTR-8/SVneo cells, in addition to isolated first trimester CT, to IL8. Exogenous IL8/CXCL8 increased trophoblast cell migration and invasion, which may be partly attributable to stimulation of MMP2 and MMP9 levels and an increase in integrins. HTR-8/SVneo cell viability and proliferation were also increased.

Regulation of monocyte chemotactic protein-1 expression in human endometrial endothelial cells by sex steroids: a potential mechanism for leukocyte recruitment in endometriosis

The main aim of this study is to describe the in vivo temporal and spatial expression of monocyte chemotactic protein 1 (MCP-1) in human endometrial endothelial cells (HEECs) and to compare the in vitro regulation of MCP-1 expression by sex steroids in HEECs from women with or without endometriosis. Eutopic endometrial tissues and endometriosis implants were grouped according to the menstrual cycle phase and were examined by immunohistochemistry for MCP-1 expression. No significant difference was observed for MCP-1 immunoreactivity in the endothelial cells of eutopic endometrium of women with endometriosis when compared to endometrium of women without endometriosis and to endometriosis implants. For in vitro studies, the purity of cultured HEECs (90%-95%) was confirmed by immunocytochemistry using endothelium-specific markers CD31 and CD146. The effects of estradiol (5 x 10(- 8) mol/L), progesterone (10(-7) mol/L), or both on MCP-1 messenger RNA (mRNA) and protein levels were analyzed by reverse transcriptase-polymerase chain reaction (RT-PCR) analysis and enzyme-linked immunosorbent serologic assay (ELISA), respectively. Sex steroids did not have significant effect on MCP-1 mRNA and protein expression in HEECs from women without endometriosis. However, we observed that the sex steroid treatment stimulated MCP-1 mRNA and protein expression in HEECs from women with endometriosis (P < .05). We postulate that the stimulation of chemokine expression by sex steroids in the endometrial endothelial cells in women with endometriosis may play a central role in recruiting mononuclear cells, therefore contributing to the inflammatory aspect of endometriosis.

Prokineticin 1 modulates IL-8 expression via the calcineurin/NFAT signaling pathway

Prokineticins and their receptors are expressed in various cellular compartments in human endometrium, with prokineticin 1 (PROK1) showing a dynamic pattern of expression across the menstrual cycle and during pregnancy. Previous studies suggest that PROK1 can play an important role in implantation and early pregnancy by inducing vascular remodeling and increasing vascular permeability. Here we demonstrate that PROK1 induces the expression of IL-8, a chemokine with angiogenic properties, in endometrial epithelial Ishikawa cells stably expressing prokineticin receptor 1 and in human first trimester decidua. We also show that IL-8 promoter activity is induced by PROK1 and that this requires the presence of AP1 and NFAT motifs. The role of calcineurin/NFAT signaling pathway is confirmed by the use of specific chemical inhibitors. Additionally, PROK1 induces the expression of the regulator of calcineurin 1 isoform 4 (RCAN1-4) via the calcineurin/NFAT pathway. A modulatory role for RCAN1-4 is demonstrated by RCAN1-4 overexpression which results in the inhibition of PROK1-induced IL-8 expression whereas reduction in RCAN1-4 endogenous expression results in an increase in PROK1-induced IL-8 production. Our findings show that in endometrial cells PROK1 can activate the calcineurin/NFAT pathway to induce IL-8 expression and that this is negatively modulated by the induction of expression of RCAN1-4.

Interleukin (IL)-1beta stimulates migration and survival of first-trimester villous cytotrophoblast cells through endometrial epithelial cell-derived IL-8

IL-1, secreted by human embryos and trophoblast cells, is important for successful implantation and pregnancy. We previously reported that IL-1beta induced IL-8 production in human endometrial stromal cells (ESCs) and that induction was regulated by substances implicated in implantation. In the present study using human primary cells in culture, we measured IL-1beta-induced production of IL-8 from endometrial epithelial cells (EECs) and ESCs and examined effects of the endometrium-derived IL-8 on migration and number of first-trimester villous cytotrophoblast cells (vCTs). Both basal and IL-1beta-induced IL-8 levels of cell supernatants were much higher in EECs than ESCs. Addition of IL-1beta to EECs increased the chemotactic activity of the supernatants to vCTs, and this effect was suppressed by immunoneutralization with anti-IL-8 antibody. Supernatants of IL-1beta-stimulated EECs yielded significantly higher number of vCTs compared with those of untreated EECs, and the effect was inhibited by IL-8 antibody. These findings suggest that IL-1 promotes implantation by stimulating EECs to produce IL-8, which subsequently induces migration of vCTs and contributes to survival of vCTs.

Extracellularly signal-regulated kinase activity in the human endometrium: possible roles in the pathogenesis of endometriosis

CONTEXT

Endometriosis is an estrogen-dependent disease characterized by the presence of endometrial tissue outside of the uterine cavity, causing pelvic pain and infertility in 10% of reproductive-aged women. It is unclear why ectopic endometrium remains viable in only a subset of women. ERK1/2 plays key intracellular roles in activating cellular survival and differentiation processes.

OBJECTIVE

We sought to determine ERK1/2 activity in patients with endometriosis and its possible roles in regulating endometrial cell survival.

DESIGN

ERK1/2 phosphorylation and expression throughout the menstrual cycle were evaluated in vivo in normal and endometriotic human endometrium, and in vitro techniques assessed the steroidal regulation of ERK1/2 and its effect on endometrial cell survival.

RESULTS

Total ERK1/2 remained constant in normal and endometriotic endometrium throughout the menstrual cycle. Phospho-ERK1/2 was high in the late proliferative and secretory phases in normal endometrium (P < 0.05). In endometriotic glandular cells, there was no cyclical variation in phospho-ERK1/2. In endometriotic stromal cells, there was also a reduction in phospho-ERK1/2 variation, with higher levels in the early-mid secretory phase (P < 0.05). In cultured endometrial stromal cells (ESCs), estrogen plus progesterone increased ERK1/2 phosphorylation within 15 min (P < 0.05). Although estrogen alone did not induce ERK1/2 phosphorylation in normal ESCs, there was a significant response to estrogen in ESCs isolated from eutopic endometriotic endometrium (P < 0.05). ERK1/2 inhibition in ESCs reduced proliferation and increased apoptosis (P < 0.05).

CONCLUSION

Abnormally high levels of ERK1/2 activity may be involved in endometriosis, possibly by stimulating endometrial cell survival.

DNA-binding ability of NF-kappaB is affected differently by ERalpha and ERbeta and its activation results in inhibition of estrogen responsiveness

Estrogenic effects involve interactions between estrogen receptors (ERs), response elements, and nuclear proteins. It is hypothesized that interaction between ER and NF-kappa B may affect the regulation of responsive genes. Electrophoretic mobility shift assay (EMSA) was performed to assess if the interaction of ERs and NF- kappaB affect their respective DNA-binding activities, and alkaline phosphatase assay was done to evaluate estrogenic activity. EMSA revealed that ERs inhibit DNA-binding of p50 and p65, whereas p50 did not impair ER alpha binding. Stimulation with estradiol inhibited DNA binding of NF-kappaB in ERalpha-transfected endometrial stromal cells (ESCs). Moreover, activation of NF-kappaB significantly decreased estrogen responsiveness of Ishikawa cells and ERalpha-transfected ESC. Our results suggest that ERs downregulate NF-kappaB-dependent gene activation by directly preventing DNA binding. However, NF-kappaB-mediated inhibition of ER-dependent gene activation may be carried out indirectly rather than through a direct inhibition of ER-DNA binding. These findings offer new insight into the specific role of ERalpha and could eventually help in developing therapeutics for endometriosis.

Expression and regulation of c-Jun N-terminal kinase (JNK) in endometrial cells in vivo and in vitro

JNK(c-Jun N-terminal kinase) is one of the main types of mitogen-activated protein kinases. JNK modulates inflammation and apoptosis in response to stress. Our hypothesis is that temporal and spatial changes in JNK activity regulate inflammation in human endometrium and that fluctuation in estrogen and progesterone levels may play a role in JNK activation. Therefore, we aimed to determine total-(t-) and active-(phosphorylated, p-) JNK expression in endometrial tissues in vivo by immunohistochemistry, and in vitro by immunocytochemistry and Western blot analysis. Immunohistochemistry revealed moderate cytoplasmic and nuclear t-JNK immunoreactivity, and mostly nuclear p-JNK immunoreactivity throughout the menstrual cycle and early pregnancy. The highest p- and t-JNK immunoreactivity was detected in late secretory phase (P < 0.05). We observed that endometrial stromal cell (ESC)s showed a significant increase in p-JNK expression following 48 h of estrogen combined with progesterone (E(2) + P(4)) withdrawal from the culture conditions, compared to control and non-withdrawal groups (P < 0.05). Upon treatment with JNK inhibitor SP600125, we observed a significantly decreased interleukin (IL)-8 level (P < 0.05) in the presence and absence of E(2). These results demonstrate that JNK expression increases during the late secretory phase when the inflammatory response is highest. Inhibition of IL-8 expression by SP600125 suggests that JNK is involved in regulation of proinflammatory mediators of endometrium.

Basal and cytokine-stimulated production of epithelial neutrophil activating peptide-78 (ENA-78) and interleukin-8 (IL-8) by cultured human endometrial epithelial and stromal cells

OBJECTIVE

To analyze the constitutive production of epithelial neutrophil activating peptide 78 (ENA-78) and interleukin-8 (IL-8) by epithelial cells and the response of these cells to cytokine stimulation.

DESIGN

In vitro study using eutopic endometrial tissue.

SETTING

University hospital.

PATIENT(S)

Cycling women undergoing laparoscopy for reasons of infertility or unexplained abdominal pain.

INTERVENTION(S)

Isolation of epithelial and stromal cells from endometrium, immunocytochemical characterization and separate culture of these cells in presence of IL-1, tumor necrosis factor alpha (TNF-alpha), and interferon-gamma.

MAIN OUTCOME MEASURE(S)

Quantitation of IL-8 and ENA-78 released into the medium by ELISA. Polymerase chain reaction was used to demonstrate the presence of ENA-78 in the cell lysate.

RESULT(S)

High purity of the endometrial epithelial cell preparation before culture was demonstrated by the lack of immunocytochemical staining for CD10. Stromal cell preparations were CD10 positive and cytokeratin negative. Stromal cells produced ENA-78 and IL-8 under cytokine stimulation, and epithelial cells were found not only to produce these markers in the absence of cytokine stimulation, but also to increase this output in the presence of IL-1beta or of TNF-alpha plus interferon-gamma.

CONCLUSION(S)

This response may be an important angiogenic step in the early stages in the pathogenesis of endometriosis.

Tenascin is highly expressed in endometriosis and its expression is upregulated by estrogen

OBJECTIVE

To investigate the localization of tenascin expression in the endometrium of women without endometriosis and in endometriotic implants, and to determine the in vitro regulation of tenascin by E(2) in these tissues.

DESIGN

Experimental laboratory study.

SETTING

University medical center.

PATIENT(S)

Reproductive age women with or without endometriosis.

INTERVENTION(S)

Proliferative (n = 14), and secretory (n = 14) endometrium from women without endometriosis and endometriosis implants (n = 14) were used for immunohistochemical analysis. Endometrial and endometriotic stromal cells were grown in culture and treated with E(2), the estrogen receptor antagonist ICI 182 780 (ICI) alone, E(2) in combination with ICI, or vehicle (control) for 24 hours, and tenascin expression was analyzed by Western blotting.

MAIN OUTCOME MEASURE(S)

Expression levels of tenascin in normal endometrium and endometriotic implants and its regulation by E(2).

RESULT(S)

Tenascin immunostaining revealed an increasing intensity in the stromal cells, starting from normal secretory endometrium, then normal proliferative endometrium, and reaching the highest expression in endometriotic implants. Estradiol induced a significant increase in tenascin protein levels in the endometriotic stromal cells in culture.

CONCLUSION(S)

The modulation of tenascin as an extracellular matrix protein by E(2) in endometriotic stromal cells may be one of the factors playing a role in the development of endometriosis.

Demonstration of multipotent stem cells in the adult human endometrium by in vitro chondrogenesis

Stem cells are defined by their unique capacity for self-renewal and multilineage differentiation. Stem cells have been obtained from multiple extramedullary tissues. Recently, a population of progenitor cells have been identified in the endometrium. However, multilineage differentiation of endometrial stem cells has not been reported. Endometrial tissue was obtained from reproductive-aged women undergoing surgery for benign disease, from which monolayer endometrial stromal cell (ESC), myometrial, fibroid, fallopian tube, and uterosacral ligament tissue cultures were generated. Once confluent, cells were trypsinized and centrifuged in conical tubes to form a cell pellet. Cell pellets were cultured in a defined chondrogenic media (CM) containing dexamethasone and transforming growth factor (TGF)-beta2 or TGF-beta 3 for 3 to 21 days. Samples were analyzed for markers of human articular cartilage, including sulfated glycosaminoglycans and expression of type II collagen. ESC pellets cultured in CM were found to contain cells that resemble chondrocytes. These cells expressed sulfated glycosaminoglycans and type II collagen typical of human articular cartilage. Myometrial, fibroid, fallopian tube, and uterosacral ligament cells were unable to undergo chondrogenic differentiation using the pellet culture method. Cells derived from the endometrium were able to differentiate into a heterologous cell type: chondrocytes, thus demonstrating the presence of multipotent stem cells. Endometrium is a potential source of multipotent stem cells.