Vascular endothelial growth factor expression in human endometrium is regulated by hypoxia

Effects of plasma acid on rat uterine tissue <i>in vitro</i>

The aim of the study was to evaluate the effect of plasma acid on the uterine tissue of laboratory animals in vitro.

Materials and methods. Treatment of dimethyl sulfoxide – water solution and water for injections with a spark discharge in air resulted in a decrease in pH, which contributed to generation of plasma acid in the solutions. We incubated uterine tissues in vitro in plasma acid at room temperature for 30 minutes. The treated tissues were examined histologically and immunohistochemically.

Results. We showed that plasma acid had pronounced biological activity. Immunohistochemistry was used to show that, depending on the type of a solution, plasma acid altered generation of nitrosative damage products (3-NT) and oxidative DNA damage (8-OHdG) and modulated the number of cells with high proliferative potential (including CD133+ cells) and production of vascular endothelial growth factor (VEGF). These effects contributed to the general cytotoxicity of plasma acid solutions.

Conclusion. During 30-minute exposure in vitro, plasma acid prepared from the dimethyl sulfoxide (DMSO) – water mixture exhibits various biological effects in uterine tissue samples obtained from experimental animals. Plasma-treated water exerts cytotoxic effects associated with oxidative DNA damage and promotes induction of pro-angiogenic activity in the uterine tissue. Plasma-treated DMSO does not have a cytotoxic effect. It inhibits cell proliferation, reducing the population of CD133+ cells and VEGF production in the tissue.

Immunology and Immunotherapy of Endometriosis

Endometriosis is one of the most common gynecological and systemic diseases, with a remarkable immune background. Patients suffer from pain and fertility reduction. Due to the distinct immune component, an immunotherapeutic approach may gain importance in the future. In endometriosis, shifts in the cell fractions of the immune system are well known. Moreover, hypoxia concomitant with inflammation causes a disturbed immune response. The removal of endometriosis has a therapeutic effect, normalizes the immune disorders, and remains the most effective causative treatment in terms of pain and infertility. A key issue is whether a similar effect can be achieved for fertility with non-invasive immunotherapy where surgery is inadvisable or cannot be performed for various reasons. Numerous immunotherapy trials, including vaccines, were conducted on animals only, although the research is encouraging. Among the promising methods of non-specific immunotherapy is the administration of an ethiodized oil contrast. Moreover, due to the significant successes of immunotherapy in oncology, the possibility of immunotherapy affecting NK cells has been postulated. NK cells are responsible for the surveillance and apoptosis of ectopic cells. Expanding the arsenal of endometriosis treatment by immunotherapy is promising due to the significant contribution of immunological factors and the limitations of current treatment methods.

Menstruation Dysregulation and Endometriosis Development

Endometriosis is a common gynecological condition characterized by the growth of endometrial-like tissue outside of the uterus which may cause symptoms such as chronic pelvic pain or subfertility. Several surgical and medical therapies are available to manage symptoms, but a cure has yet to be determined which can be attributed to the incomplete understanding of disease pathogenesis. Sampson's theory of retrograde menstruation is a widely accepted theory describing how shed endometrial tissue can enter the peritoneal cavity, but other factors are likely at play to facilitate the establishment of endometriosis lesions. This review summarizes literature that has explored how dysregulation of menstruation can contribute to the pathogenesis of endometriosis such as dysregulation of inflammatory mediators, aberrant endometrial matrix metalloproteinase expression, hypoxic stress, and reduced apoptosis. Overall, many of these factors have overlapping pathways which can prolong the survival of shed endometrial debris, increase tissue migration, and facilitate implantation of endometrial tissue at ectopic sites. Moreover, some of these changes are also implicated in abnormal uterine bleeding and endometrial diseases. More research is needed to better understand the underlying mechanisms driving dysregulation of menstruation in endometriosis specifically and identifying specific pathways could introduce new treatment targets. Analyzing menstrual fluid from women with endometriosis for inflammatory markers and other biomarkers may also be beneficial for earlier diagnosis and disease staging.

Identifying Common Pathogenic Features in Deep Endometriotic Nodules and Uterine Adenomyosis

Increasing imaging data point to a link between deep endometriotic nodules (DENs) and uterine adenomyosis (AD). The study aimed to investigate this link at the histological level and detect potential features shared by the two diseases. We collected formalin-fixed paraffin-embedded tissue (endometrium and lesions) from women with DENs of the rectovaginal septum (n = 13), AD (n = 14), and control subjects (n = 14). Immunohistochemical analyses of CD41 and CD68 were conducted to explore the roles of platelets and macrophages, respectively. Picrosirius red staining was carried out to gather evidence of fibrosis. Vascular endothelial growth factor (VEGF) was assessed, and total numbers of CD31-positive vessels were calculated to investigate the mechanism governing angiogenesis. Double immunohistochemistry for CD31 and alpha smooth muscle actin (αSMA) was performed to discern stable vessels. Platelet aggregation was significantly decreased in both types of lesions compared to their corresponding eutopic endometrium and healthy controls. Macrophage numbers were higher in both lesions than in their corresponding endometrium and healthy subjects. Significantly higher rates of collagen accumulation were detected in DENs and AD lesions compared to their corresponding eutopic and healthy endometrium. VEGF expression was downregulated in the stromal compartment of AD lesions compared to the healthy endometrium. The total number of vessels per area was significantly higher in DENs and AD lesions than in the healthy endometrium. Rates of αSMA-surrounded vessels were decreased in DENs and AD lesions compared to their corresponding eutopic and healthy endometrium. We report common pathogenic mechanisms between DENs and AD, namely excessive macrophage accumulation, fibrosis, and irregular angiogenesis. Our results further support the notion of DENs and AD being linked at the histological level.

Meloxicam Inhibited the Proliferation of LPS-Stimulated Bovine Endometrial Epithelial Cells Through Wnt/β-Catenin and PI3K/AKT Pathways

Meloxicam is a non-steroidal anti-inflammatory drug and has been used to relieve pain and control inflammation in cows with metritis and endometritis. Meloxicam has been found to be effective in inhibiting tissue or cell growth when it is used as an anti-inflammatory therapy. However, the influence of meloxicam on bovine endometrial regeneration has not been reported. This study was to research the effect of meloxicam (0.5 and 5 μM) on the proliferation of primary bovine endometrial epithelial cells (BEECs) stimulated by Escherichia coli lipopolysaccharide. The cell viability, cell cycle, and cell proliferation were evaluated by Cell Counting Kit-8, flow cytometry, and cell scratch test, respectively. The mRNA transcriptions of prostaglandin-endoperoxide synthase 1 (PTGS1) and PTGS2, Toll-like receptor 4, and proliferation factors were detected using quantitative reverse-transcription polymerase chain reaction. The activations of phosphatidylinositol 3-kinase (PI3K)/protein kinase B (AKT) and Wnt/β-catenin pathways were determined using western blot and immunofluorescence. As a result, co-treatment of meloxicam and lipopolysaccharide inhibited (P < 0.05) the cell cycle progression and reduced (P < 0.05) the cell healing rate and the mRNA level of proliferation factors as compared with the cells treated with lipopolysaccharide alone. Meloxicam decreased (P < 0.05) the lipopolysaccharide-induced PTGS2 gene expression. Neither lipopolysaccharide nor meloxicam changed PTGS1 mRNA abundance (P > 0.05). Meloxicam inhibited (P < 0.05) the lipopolysaccharide-activated Wnt/β-catenin pathway by reducing (P < 0.05) the protein levels of β-catenin, c-Myc, cyclin D1, and glycogen synthase kinase-3β and prevented the lipopolysaccharide-induced β-catenin from entering the nucleus. Meloxicam suppressed (P < 0.05) the phosphorylation of PI3K and AKT. In conclusion, meloxicam alone did not influence the cell cycle progression or the cell proliferation in BEEC but caused cell cycle arrest and inhibited cell proliferation in lipopolysaccharide-stimulated BEEC. This inhibitory effect of meloxicam was probably mediated by Wnt/β-catenin and PI3K/AKT pathways.

Pharmaceuticals targeting signaling pathways of endometriosis as potential new medical treatment: A review

Endometriosis (EM) is defined as endometrial tissues found outside the uterus. Growth and development of endometriotic cells in ectopic sites can be promoted via multiple pathways, including MAPK/MEK/ERK, PI3K/Akt/mTOR, NF-κB, Rho/ROCK, reactive oxidative stress, tumor necrosis factor, transforming growth factor-β, Wnt/β-catenin, vascular endothelial growth factor, estrogen, and cytokines. The underlying pathophysiological mechanisms include proliferation, apoptosis, autophagy, migration, invasion, fibrosis, angiogenesis, oxidative stress, inflammation, and immune escape. Current medical treatments for EM are mainly hormonal and symptomatic, and thus the development of new, effective, and safe pharmaceuticals targeting specific molecular and signaling pathways is needed. Here, we systematically reviewed the literature focused on pharmaceuticals that specifically target the molecular and signaling pathways involved in the pathophysiology of EM. Potential drug targets, their upstream and downstream molecules with key aberrant signaling, and the regulatory mechanisms promoting the growth and development of endometriotic cells and tissues were discussed. Hormonal pharmaceuticals, including melatonin, exerts proapoptotic via regulating matrix metallopeptidase activity while nonhormonal pharmaceutical sorafenib exerts antiproliferative effect via MAPK/ERK pathway and antiangiogenesis activity via VEGF/VEGFR pathway. N-acetyl cysteine, curcumin, and ginsenoside exert antioxidant and anti-inflammatory effects via radical scavenging activity. Natural products have high efficacy with minimal side effects; for example, resveratrol and epigallocatechin gallate have multiple targets and provide synergistic efficacy to resolve the complexity of the pathophysiology of EM, showing promising efficacy in treating EM. Although new medical treatments are currently being developed, more detailed pharmacological studies and large sample size clinical trials are needed to confirm the efficacy and safety of these treatments in the near future.

Encapsulated VEGF121-PLA microparticles promote angiogenesis in human endometrium stromal cells

Background

In this study, Vascular Endothelial Growth Factor 121 expressed abundantly in endometrial stromal cells is encapsulated with poly-l-lactide and characterized the properties for endometrial angiogenesis. We studied the migration, proliferation and the protein levels of human immortalized endometrium stromal cells after treating the cells with recombinant Vascular Endothelial Growth Factor (200 and 500 nanogram), and poly-l-lactide loaded Vascular Endothelial Growth Factor 121 (day 1, 20 and 30). The present study explains endometrium angiogenesis because endometrium plays an important role in pregnancy.

Results

Migration and proliferation studies in endometrium cells proved the efficiency of Vascular Endothelial Growth Factor and poly-l-lactide loaded Vascular Endothelial Growth Factor 121. This proliferated and increased the migration of the cells in vitro and also activated the Protein kinase B, Phosphatidylinositol-4, 5-Bisphosphate 3-Kinase Catalytic Subunit Beta, α-Smooth muscle actin and vascular endothelial growth factor receptor 2 pathways. Western blot analysis showed the increased expression levels of kinases, smooth muscle actin and vascular endothelial growth factor receptor 2 after the treatment with Vascular Endothelial Growth Factor and poly-l-lactide loaded Vascular Endothelial Growth Factor 121 particles in comparison to the control group. The elevated levels of α-Smooth muscle actin in endometrium cells with Vascular Endothelial Growth Factor prove the regulation of angiogenesis in vitro.

Conclusion

Endometrium thickness is one of the important factors during implantation of embryo and pregnancy. Slow release of VEGF from PLA encapsulated microparticle further controls the endothelial cell proliferation and migration and helps in the promotion of angiogenesis. The combined effect studied in vitro could be used as a pro-angiogenic drug on further in vivo confirmation.

Macrophage Plasticity in Reproduction and Environmental Influences on Their Function

Macrophages are key components of the innate immune system and exhibit extensive plasticity and heterogeneity. They play a significant role in the non-pregnant cycling uterus and throughout gestation they contribute to various processes underpinning reproductive success including implantation, placentation and parturition. Macrophages are also present in breast milk and impart immunomodulatory benefits to the infant. For a healthy pregnancy, the maternal immune system must adapt to prevent fetal rejection and support development of the semi-allogenic fetus without compromising host defense. These functions are dependent on macrophage polarization which is governed by the local tissue microenvironmental milieu. Disruption of this microenvironment, possibly by environmental factors of infectious and non-infectious origin, can affect macrophage phenotype and function and is linked to adverse obstetric outcomes, e.g. spontaneous miscarriage and preterm birth. Determining environmental influences on cellular and molecular mechanisms that control macrophage polarization at the maternal-fetal interface and the role of this in pregnancy complications could support approaches to alleviating adverse pregnancy outcomes.

Pathophysiological implications of hypoxia in human diseases

Oxygen is essentially required by most eukaryotic organisms as a scavenger to remove harmful electron and hydrogen ions or as a critical substrate to ensure the proper execution of enzymatic reactions. All nucleated cells can sense oxygen concentration and respond to reduced oxygen availability (hypoxia). When oxygen delivery is disrupted or reduced, the organisms will develop numerous adaptive mechanisms to facilitate cells survived in the hypoxic condition. Normally, such hypoxic response will cease when oxygen level is restored. However, the situation becomes complicated if hypoxic stress persists (chronic hypoxia) or cyclic normoxia-hypoxia phenomenon occurs (intermittent hypoxia). A series of chain reaction-like gene expression cascade, termed hypoxia-mediated gene regulatory network, will be initiated under such prolonged or intermittent hypoxic conditions and subsequently leads to alteration of cellular function and/or behaviors. As a result, irreversible processes occur that may cause physiological disorder or even pathological consequences. A growing body of evidence implicates that hypoxia plays critical roles in the pathogenesis of major causes of mortality including cancer, myocardial ischemia, metabolic diseases, and chronic heart and kidney diseases, and in reproductive diseases such as preeclampsia and endometriosis. This review article will summarize current understandings regarding the molecular mechanism of hypoxia in these common and important diseases.

Regenerative therapy by endometrial mesenchymal stem cells in thin endometrium with repeated implantation failure. A novel strategy

OBJECTIVE

Our primary objective was to evaluate the endometrial changes before and after the transfer of endometrial mesenchymal stem cells (enMSCs) in a population of thinned endometrium women, with absence or hypo-responsiveness to estrogen and repeated implantation failure (RIF). The secondary objective was to evaluate the clinical outcomes of the intervention in terms of clinical pregnancy (CP), early abortions, ongoing pregnancy and live birth delivery rate (LBDR) per in vitro fertilization (IVF) cycle.

METHODS

A longitudinal and experimental study. The intervention was defined as "subendometrial inoculation of enMSCs," and the post-intervention changes were evaluated by the following variables: endometrial thickness (Eth), endometrial flow cytometry (enFC), endometrial histopathology (enHP) and endometrial immunohistochemistry (enIHQ). The variables were analyzed after the intervention (Post-treatment) regarding previous values (Pretreatment).

RESULTS

Eth values before and after treatment with enMSCs were 5.24±1.24 mm vs. 9.93±0.77 (p=0.000), respectively. Endometrial Flow Cytometry showed significant differences in favor of Normalized variables in the post-treatment assessment, associated with the pretreatment, LT/Li, LB/Li, NK/Li, CD8/CD3+ and CD4/CD8 (p≤0.015), respectively. Only two variables Li/PC and CD4/CD3 had NS (p=0.167 and 0.118). A similar analysis was performed on enHP with an HP increase post-treatment (p=0.007). The CP rate was 79.31% (23/29), a live birth delivery rate per embryo transfer was 45.45% (10/22) and ongoing pregnancy 7/29 (24.14%).

CONCLUSION

Subendometrial enMSCs inoculation produces a significant increase in endometrial thickness; normalize the enHP, enIHQ and enFC. As a result, IVF after treatment with enMSCs yields a higher rate of CP and LBDR.

Evaluation of recombinant human vascular endothelial growth factor VEGF121-loaded poly-l-lactide microparticles as a controlled release delivery system

Vascular endothelial growth factor A (VEGF-A) is an important growth factor that plays a major role in angiogenesis. With different isoforms distributed in various tissues, the shortest isoform of VEGF-A is VEGF121, one of the physiologically functional variants next to VEGF165. It is well known that VEGF has a shorter half-life, and the stability of the protein must be considered in therapeutic aspects. Poly-l-lactide (PLA) microparticles can release the encapsulated protein in a sustained release mode. In this study, the VEGF121 gene was cloned and expressed in a prokaryotic expression system (Escherichia coli). The recombinant VEGF121 was encapsulated with PLA microparticles and studied in vitro  and ex ovo  for the sustained release mechanism. The PLA-VEGF microparticles and the recombinant VEGF121 were explored for their bioactivity in human umbilical vein endothelial cells (HUVEC). VEGF released in vitro  from PLA microparticles on days 1, 20, and 30 showed remarkable biological activity compared to PBS-loaded PLA microparticles such as the ability of the cells to proliferate, migrate, and form tubes similar to recombinant VEGF121. Besides, PLA-VEGF microparticles and the recombinant VEGF121 were also tested for their proangiogenic action in embryonated eggs by chicken chorioallantoic membrane assay (CAM), and the effect was observed in both forms. This study suggests that PLA-loaded VEGF microparticles in a sustainable release format can be effectively used in proangiogenic therapy and reduce the adverse effects caused due to multiple dosages.

Endometriosis-Associated Macrophages: Origin, Phenotype, and Function

Endometriosis is a complex, heterogeneous, chronic inflammatory condition impacting ~176 million women worldwide. It is associated with chronic pelvic pain, infertility, and fatigue, and has a substantial impact on health-related quality of life. Endometriosis is defined by the growth of endometrial-like tissue outside the uterus, typically on the lining of the pelvic cavity and ovaries (known as "lesions"). Macrophages are complex cells at the center of this enigmatic condition; they are critical for the growth, development, vascularization, and innervation of lesions as well as generation of pain symptoms. In health, tissue-resident macrophages are seeded during early embryonic life are vital for development and homeostasis of tissues. In the adult, under inflammatory challenge, monocytes are recruited from the blood and differentiate into macrophages in tissues where they fulfill functions, such as fighting infection and repairing wounds. The interplay between tissue-resident and recruited macrophages is now at the forefront of macrophage research due to their differential roles in inflammatory disorders. In some cancers, tumor-associated macrophages (TAMs) are comprised of tissue-resident macrophages and recruited inflammatory monocytes that differentiate into macrophages within the tumor. These macrophages of different origins play differential roles in disease progression. Herein, we review the complexities of macrophage dynamics in health and disease and explore the paradigm that under disease-modified conditions, macrophages that normally maintain homeostasis become modified such that they promote disease. We also interrogate the evidence to support the existence of multiple phenotypic populations and origins of macrophages in endometriosis and how this could be exploited for therapy.

The proliferative effect of cortisol on bovine endometrial epithelial cells

BACKGROUND

Bovine endometrial epithelial cells (BEECs) undergo regular regeneration after calving. Elevated cortisol concentrations have been reported in postpartum cattle due to various stresses. However, the effects of the physiological level of cortisol on proliferation in BEECs have not been reported. The aim of this study was to investigate whether cortisol can influence the proliferation properties of BEECs and to clarify the possible underlying mechanism.

METHODS

BEECs were treated with different concentrations of cortisol (5, 15 and 30 ng/mL). The mRNA expression of various growth factors was detected by quantitative reverse transcription-polymerase chain reaction (qPCR), progression of the cell cycle in BEECs was measured using flow cytometric analysis, and the activation of the Wnt/β-catenin and phosphatidylinositol 3-kinase (PI3K)/protein kinase B (AKT) signaling pathways was detected with Western blot and immunofluorescence.

RESULTS

Cortisol treatment resulted in upregulated mRNA levels of vascular endothelial growth factor (VEGF) and connective tissue growth factor (CTGF); however, it had no influence on transforming growth factor-beta1 (TGF-β1). Cortisol (15 ng/mL) accelerated the cell cycle transition from the G0/G1 to the S phase. Cortisol upregulated the expression of β-catenin, c-Myc, and cyclinD1 and promoted the phosphorylation of PI3K and AKT.

CONCLUSIONS

These results demonstrated that cortisol may promote proliferation in BEECs by increasing the expression of some growth factors and activating the Wnt/β-catenin and PI3K/AKT signaling pathways.

The synergistic effect of electroacupuncture and bone mesenchymal stem cell transplantation on repairing thin endometrial injury in rats

BACKGROUND

Tissue regeneration disorder after endometrial injury is an important cause of intrauterine adhesions, amenorrhea, and infertility in women. Both bone marrow mesenchymal stem cell (BMSC) transplantation and electroacupuncture (EA) are promising therapeutic applications for endometrial injury. This study examined their combined effects on thin endometrium in rats and the possible mechanisms underlying these effects.

METHODS

A thin endometrial model was established in Sprague-Dawley (SD) rats by perfusing 95% ethanol into the right side of the uterus. The wounds were randomly treated with PBS (model group), BMSCs only (BMSC group), EA only (EA group), and BMSCs combined with EA (BMSC + EA group). Endometrial morphological alterations were observed by hematoxylin and eosin (H&E) staining. Changes in markers of epithelial and stromal endometrium cells, endometrial receptivity-related chemokines, and paracrine factors were detected using immunohistochemistry, western blotting, and quantitative reverse-transcription polymerase chain reaction (qRT-PCR). Finally, the functional recovery of the uterus was evaluated by determining the rate of embryo implantation.

RESULTS

As shown by endometrial morphology, the damaged uteri in all the treatment groups recovered to some extent, with the best effects observed in the BMSC + EA group. Further studies showed that EA promoted the migration of transplanted BMSCs to damaged uteri by activating the stromal cell-derived factor-1/C-X-C chemokine receptor type 4 (SDF-1/CXCR4) axis. As compared with the other groups, upregulated expression of endometrial cytokeratin and vimentin, increased secretion of vascular endothelial growth factor (VEGF) and basic fibroblast growth factor (bFGF) in endometrial lesions, and improved embryo implantation rates on the 8th day of pregnancy were found in the BMSC + EA group.

CONCLUSIONS

EA plays an important role in supporting BMSCs in the repair of thin endometrium, most likely by promoting the migration of BMSCs and enhancing the paracrine effect of BMSCs.

Therapeutic Effects of VEGF Gene-Transfected BMSCs Transplantation on Thin Endometrium in the Rat Model

Objective

Bone mesenchymal stem cells (BMSCs) transplantation has a therapeutic effect on the thin endometrium in animal researches and clinical trials. The present study aims at assessing whether transplantation of VEGF-transfected BMSCs (VEGF-BMSCs) have a better therapeutic effect on endometrial regeneration and endometrial receptivity compared with BMSCs therapy alone.

Methods

Sprague-Dawley (SD) rats were used in the study. Thin endometrium model was established with 95% ethanol injection into uterine. VEGF-BMSCs or BMSCs was transplanted via tail vein IV injection. Endometrial thickness, morphology, and pinopodes were assessed by hematoxylin and eosin (HE) staining and scanning electron microscope (SEM). The proteins and mRNAs expressions of markers for endometrial cells and endometrial receptivity were measured after treatment. The fertility testing was done to assess the embryo implantation efficiency.

Results

VEGF-BMSCs transplantation significantly increased endometrial thickness compared with the BMSCs group and the control group. There was no significant difference in endometrial thickness between VEGF-BMSCs group and sham operation group. Importantly, in protein level, expressions of cytokeratin, vitamin, VEGF, LIF, and integrin α_νβ ₃ in VEGF-BMSC group were increased dramatically compared with those of the control group and BMSC group both 4 days and 8 days after stem cells transplantation. Accordingly, mRNA expression of LIF and integrin α _ν β ₃ was significantly upregulated compared with those of the control group and BMSC group both 4 and 8 days after treatment. The pinopodes were developed better in the VEGF-BMSCs group and the sham operation group compared with BMSCs group and the control group. The number of embryo implantation is largest in the sham operation group, followed by VEGF-BMSCs group, BMSCs group, and the control group.

Conclusions

Transplantation of VEGF gene-transfected BMSCs may be a better therapeutic treatment for thin endometrium than stem cell therapy alone.

Inside the Endometrial Cell Signaling Subway: Mind the Gap(s)

Endometrial cells perceive and respond to their microenvironment forming the basis of endometrial homeostasis. Errors in endometrial cell signaling are responsible for a wide spectrum of endometrial pathologies ranging from infertility to cancer. Intensive research over the years has been decoding the sophisticated molecular means by which endometrial cells communicate to each other and with the embryo. The objective of this review is to provide the scientific community with the first overview of key endometrial cell signaling pathways operating throughout the menstrual cycle. On this basis, a comprehensive and critical assessment of the literature was performed to provide the tools for the authorship of this narrative review summarizing the pivotal components and signaling cascades operating during seven endometrial cell fate “routes”: proliferation, decidualization, implantation, migration, breakdown, regeneration, and angiogenesis. Albeit schematically presented as separate transit routes in a subway network and narrated in a distinct fashion, the majority of the time these routes overlap or occur simultaneously within endometrial cells. This review facilitates identification of novel trajectories of research in endometrial cellular communication and signaling. The meticulous study of endometrial signaling pathways potentiates both the discovery of novel therapeutic targets to tackle disease and vanguard fertility approaches.

Hypoxic conditioning in blood vessels and smooth muscle tissues: effects on function, mechanisms, and unknowns

Hypoxic preconditioning, the protective effect of brief, intermittent hypoxic or ischemic episodes on subsequent more severe hypoxic episodes, has been known for 30 yr from studies on cardiac muscle. The concept of hypoxic preconditioning has expanded; excitingly, organs beyond the heart, including the brain, liver, and kidney, also benefit. Preconditioning of vascular and visceral smooth muscles has received less attention despite their obvious importance to health. In addition, there has been no attempt to synthesize the literature in this field. Therefore, in addition to overviewing the current understanding of hypoxic conditioning, in the present review, we consider the role of blood vessels in conditioning and explore evidence for conditioning in other smooth muscles. Where possible, we have distinguished effects on myocytes from other cell types in the visceral organs. We found evidence of a pivotal role for blood vessels in conditioning and for conditioning in other smooth muscle, including the bladder, vascular myocytes, and gastrointestinal tract, and a novel response in the uterus of a hypoxic-induced force increase, which helps maintain contractions during labor. To date, however, there are insufficient data to provide a comprehensive or unifying mechanism for smooth muscles or visceral organs and the effects of conditioning on their function. This also means that no firm conclusions can be drawn as to how differences between smooth muscles in metabolic and contractile activity may contribute to conditioning. Therefore, we have suggested what may be general mechanisms of conditioning occurring in all smooth muscles and tabulated tissue-specific mechanistic findings and suggested ideas for further progress.

Shaofu Zhuyu Decoction Regresses Endometriotic Lesions in a Rat Model

The current therapies for endometriosis are restricted by various side effects and treatment outcome has been less than satisfactory. Shaofu Zhuyu Decoction (SZD), a classic traditional Chinese medicinal (TCM) prescription for dysmenorrhea, has been widely used in clinical practice by TCM doctors to relieve symptoms of endometriosis. The present study aimed to investigate the effects of SZD on a rat model of endometriosis. Forty-eight female Sprague-Dawley rats with regular estrous cycles went through autotransplantation operation to establish endometriosis model. Then 38 rats with successful ectopic implants were randomized into two groups: vehicle- and SZD-treated groups. The latter were administered SZD through oral gavage for 4 weeks. By the end of the treatment period, the volume of the endometriotic lesions was measured, the histopathological properties of the ectopic endometrium were evaluated, and levels of proliferating cell nuclear antigen (PCNA), CD34, and hypoxia inducible factor- (HIF-) 1α in the ectopic endometrium were detected with immunohistochemistry. Furthermore, apoptosis was assessed using the terminal deoxynucleotidyl transferase (TdT) deoxyuridine 5′-triphosphate (dUTP) nick-end labeling (TUNEL) assay. In this study, SZD significantly reduced the size of ectopic lesions in rats with endometriosis, inhibited cell proliferation, increased cell apoptosis, and reduced microvessel density and HIF-1α expression. It suggested that SZD could be an effective therapy for the treatment and prevention of endometriosis recurrence.

Niche matters: The comparison between bone marrow stem cells and endometrial stem cells and stromal fibroblasts reveal distinct migration and cytokine profiles in response to inflammatory stimulus

Objective

Intrinsic inflammatory characteristics play a pivotal role in stem cell recruitment and homing through migration where the subsequent change in niche has been shown to alter these characteristics. The bone marrow mesenchymal stem cells (bmMSCs) have been demonstrated to migrate to the endometrium contributing to the stem cell reservoir and regeneration of endometrial tissue. Thus, the aim of the present study was to compare the inflammation-driven migration and cytokine secretion profile of human bmMSCs to endometrial mesenchymal stem cells (eMSCs) and endometrial fibroblasts (eSFs).

Materials and methods

The bmMSCs were isolated from bone marrow aspirates through culturing, whereas eMSCs and eSFs were FACS-isolated. All cell types were tested for their surface marker, proliferation profiles and migration properties towards serum and inflammatory attractants. The cytokine/chemokine secretion profile of 35 targets was analysed in each cell type at basal level along with lipopolysaccharide (LPS)-induced state.

Results

Both stem cell types, bmMSCs and eMSCs, presented with similar stem cell surface marker profiles as well as possessed high proliferation and migration potential compared to eSFs. In multiplex assays, the secretion of 16 cytokine targets was detected and LPS stimulation expanded the cytokine secretion pattern by triggering the secretion of several targets. The bmMSCs exhibited higher cytokine secretion of vascular endothelial growth factor (VEGF)-A, stromal cell-derived factor-1 alpha (SDF)-1α, interleukin-1 receptor antagonist (IL-1RA), IL-6, interferon-gamma inducible protein (IP)-10, monocyte chemoattractant protein (MCP)-1, macrophage inflammatory protein (MIP)1α and RANTES compared to eMSCs and/or eSFs after stimulation with LPS. The basal IL-8 secretion was higher in both endometrial cell types compared to bmMSCs.

Conclusion

Our results highlight that similar to bmMSCs, the eMSCs possess high migration activity while the differentiation process towards stromal fibroblasts seemed to result in loss of stem cell surface markers, minimal migration activity and a subtler cytokine profile likely contributing to normal endometrial function.

Effect of rapamycin on endometriosis in mice

The aims of the present study were to investigate the impact of rapamycin (RAPA) on the endometriosis (EMS) lesions in severe combined immunodeficiency (SCID) mice, and to examine the possible mechanism involved in a novel therapy in EMS. Following the successful establishment of an EMS-SCID mouse model, the mice were randomly assigned into the RAPA, control and saline treatment groups. Subsequent to treatment for 2 weeks, the serum hypoxia-inducible factor-1α (HIF-1α) and vascular endothelial growth factor (VEGF) were detected using ELISA. The levels of HIF-1α and VEGF, as well as the size of EMS lesions, were compared among the three groups. In addition, the HIF-1α, VEGF and CD34 protein expression levels, and the microvessel density (MVD) of the lesions were determined by immunohistochemical analysis. Compared with the control and saline groups, the volume of EMS lesions in the RAPA-treated SCID mice was significantly reduced. Furthermore, the serum level and protein expression of VEGF, and the MVD in the lesions of the RAPA-treated group were significantly reduced when compared with the other two groups. These parameters were comparable in the control and saline groups. In conclusion, RAPA may inhibit the growth of endometriotic lesions, most possibly through the inhibition of the expression of VEGF in lesions, thereby inhibiting angiogenesis.

Computational Model of MicroRNA Control of HIF-VEGF Pathway: Insights into the Pathophysiology of Ischemic Vascular Disease and Cancer

HRMs (hypoxia-responsive miRNAs) are a specific group of microRNAs that are regulated by hypoxia. Recent studies revealed that several HRMs including let-7 family miRNAs were highly induced in response to HIF (hypoxia-inducible factor) stabilization in hypoxia, and they potently participated in angiogenesis by targeting AGO1 (argonaute 1) and upregulating VEGF (vascular endothelial growth factor). Here we constructed a novel computational model of microRNA control of HIF-VEGF pathway in endothelial cells to quantitatively investigate the role of HRMs in modulating the cellular adaptation to hypoxia. The model parameters were optimized and the simulations based on these parameters were validated against several published in vitro experimental data. To advance the mechanistic understanding of oxygen sensing in hypoxia, we demonstrated that the rate of HIF-1α nuclear import substantially influences its stabilization and the formation of HIF-1 transcription factor complex. We described the biological feedback loops involving let-7 and AGO1 in which the impact of external perturbations were minimized; as a pair of master regulators when low oxygen tension was sensed, they coordinated the critical process of VEGF desuppression in a controlled manner. Prompted by the model-motivated discoveries, we proposed and assessed novel pathway-specific therapeutics that modulate angiogenesis by adjusting VEGF synthesis in tumor and ischemic cardiovascular disease. Through simulations that capture the complex interactions between miRNAs and miRNA-processing molecules, this model explores an innovative perspective about the distinctive yet integrated roles of different miRNAs in angiogenesis, and it will help future research to elucidate the dysregulated miRNA profiles found in cancer and various cardiovascular diseases.

Cells living in a hypoxic environment secrete signals to stimulate new blood vessel growth, a process termed angiogenesis, to acquire more oxygen and nutrients. Hypoxia-inducible factor 1 (HIF-1) accumulates in hypoxia and expedites the release of pro-angiogenic cytokines such as vascular endothelial growth factor (VEGF), a prime inducer of angiogenesis. The intermediate signaling events connecting HIF-1 and VEGF are tightly controlled by microRNAs (miRs), which are endogenous, non-coding RNA molecules and powerful regulators in cancer and cardiovascular disease. Given the importance of angiogenesis in tumor development and post-ischemia reperfusion, it holds great basic research and therapeutic value to investigate how miRs modulate intracellular VEGF synthesis to control angiogenesis in hypoxia. We present a computational model that details the interactions between miRs and other key molecules which make up different hierarchies in HIF-miR-VEGF pathway. Based on simulation analysis, new potential therapies are introduced and tested in silico, from which the strategies that most effectively reduce VEGF synthesis in cancer, or enhance VEGF release in ischemic vascular disease are identified. We conclude that in hypoxia different miRs work consonantly to fine-tune the cellular adaptations; when a master miR alters its expression, dynamics of other miRs vary accordingly which together contribute to aberrant RNA/protein profiles observed in the pathophysiology of multiple diseases.

Menstrual physiology: implications for endometrial pathology and beyond

BACKGROUND

Each month the endometrium becomes inflamed, and the luminal portion is shed during menstruation. The subsequent repair is remarkable, allowing implantation to occur if fertilization takes place. Aberrations in menstrual physiology can lead to common gynaecological conditions, such as heavy or prolonged bleeding. Increased knowledge of the processes involved in menstrual physiology may also have translational benefits at other tissue sites.

METHODS

Pubmed and Cochrane databases were searched for all original and review articles published in English until April 2015. Search terms included ‘endometrium’, ‘menstruation’, ‘endometrial repair’, ‘endometrial regeneration’ ‘angiogenesis’, ‘inflammation’ and ‘heavy menstrual bleeding’ or ‘menorrhagia’.

RESULTS

Menstruation occurs naturally in very few species. Human menstruation is thought to occur as a consequence of preimplantation decidualization, conferring embryo selectivity and the ability to adapt to optimize function. We highlight how current and future study of endometrial inflammation, vascular changes and repair/regeneration will allow us to identify new therapeutic targets for common gynaecological disorders. In addition, we describe how increased knowledge of this endometrial physiology will have many translational applications at other tissue sites. We highlight the clinical applications of what we know, the key questions that remain and the scientific and medical possibilities for the future.

CONCLUSIONS

The study of menstruation, in both normal and abnormal scenarios, is essential for the production of novel, acceptable medical treatments for common gynaecological complaints. Furthermore, collaboration and communication with specialists in other fields could significantly advance the therapeutic potential of this dynamic tissue.

Pathophysiology and Immune Dysfunction in Endometriosis

Endometriosis is an estrogen-dependent, chronic, proinflammatory disease prevalent in 10% of women of reproductive age worldwide. Characterized by the growth of endometrium-like tissue in aberrant locations outside of the uterus, it is responsible for symptoms including chronic pelvic pain, dysmenorrhea, and subfertility that degrade quality of life of women significantly. In Canada, direct and indirect economic cost of endometriosis amounts to 1.8 billion dollars, and this is elevated to 20 billion dollars in the United States. Despite decades of research, the etiology and pathophysiology of endometriosis still remain to be elucidated. This review aims to bring together the current understanding regarding the pathogenesis of endometriosis with specific focus on mechanisms behind vascularization of the lesions and the contribution of immune factors in facilitating lesion establishment and development. The role of hormones, immune cells, and cytokine signaling is highlighted, in addition to discussing the current pharmaceutical options available for management of pain symptoms in women with endometriosis.

Effect of shRNA-mediated knockdown of vascular endothelial growth factor on the proliferation of choroid-retinal endothelial cells under hypoxic conditions

The aim of the present study was to investigate the role of vascular endothelial growth factor (VEGF) in cell proliferation under hypoxic conditions. Gene knockdown of VEGF was conducted in the choroid-retinal endothelial RF/6A cell line by transfection with short hairpin RNA (shRNA), in which a shRNA fragment against VEGF was synthesized and cloned into the vector, pSilencer 2.1-U6 neo. Subsequently, a model of hypoxia was established in the RF/6A cell line via treatment with CoCl₂, into which the recombinant plasmids, containing the VEGF-targeting shRNA (p-shRNA), were transfected. The study included four treatment groups, namely a control group (normal group), a hypoxia group treated with CoCl₂ (CoCl₂ group), a control plasmid group that were subjected to CoCl₂ treatment and transfection with a pSilencer 2.1-U6 neo plasmid without the shRNA (CoCl₂ + p-NC group), and a group treated with CoCl₂ and transfected with a pSilencer 2.1-U6 neo plasmid containing the VEGF-targeting shRNA (CoCl₂ + p-shRNA group). Subsequent to treatment, the mRNA and protein expression levels of VEGF were evaluated using quantitative polymerase chain reaction and western blot analysis, respectively, In addition, cell proliferation was assessed. RF/6A cells treated with CoCl₂ reduced cell connectivity, irregular morphology and reduced thickness compared with the cells in the normal group. However, cells in the CoCl₂ + p-shRNA group exhibited an improved morphology compared with the CoCl₂ and CoCl₂ + p-NC groups. Cell proliferation in the CoCl₂ group was enhanced in a time-dependent manner. However, the hypoxia-induced increase in cell proliferation was significantly inhibited in the CoCl₂ + p-shRNA group, with inhibition rates of 16, 32 and 38% at 24, 48 and 72 h, respectively. The mRNA and protein expression levels of VEGF were increased in the CoCl₂ group when compared with the normal group, and these hypoxia-induced increases in VEGF expression were reduced in the CoCl₂ + p-shRNA group. Therefore, the results indicated that the targeted knockdown of VEGF in vascular endothelial cells may be effective for the treatment of retinal neovascularization diseases.

Curcumin prophylaxis mitigates the incidence of hypobaric hypoxia-induced altered ion channels expression and impaired tight junction proteins integrity in rat brain

Background

The present study was proposed to elucidate the prophylactic role of curcumin in the prevention of hypoxia-induced cerebral edema (HACE).

Methods

Rats were exposed to simulated hypobaric hypoxia at 7620 m for 24 h at 25 ± 1 °C. Transvascular leakage, expression of transcriptional factors (nuclear factor-kappa B (NF-κB) and hypoxia inducible factor 1 alpha (Hif-1α) and also the genes regulated by these transcriptional factors, sodium potassium-adenosine triphosphatase (Na⁺/K⁺-ATPase) and endothelial sodium channel (ENaC) levels and brain tight junction (TJ) proteins like ZO-1, junctional adhesion molecule C (JAMC), claudin 4 and claudin 5 levels were determined in the brain of rats under hypoxia by Western blotting, electro mobility shift assay, ELISA, immunohistochemistry, and histopathology along with haematological parameters. Simultaneously, to rule out the fact that inflammation causes impaired Na⁺/K⁺-ATPase and ENaC functions and disturbing the TJ integrity leading to cerebral edema, the rats were pre-treated with curcumin (100 mg/kg body weight) 1 h prior to 24-h hypoxia.

Results

Curcumin administration to rats, under hypoxia showed a significant decrease (p < 0.001) in brain water content (3.53 ± 0.58 wet-to-dry-weight (W/D) ratio) and transvascular leakage (136.2 ± 13.24 relative fluorescence units per gram (r.f.u./g)) in the brain of rats compared to control (24-h hypoxia) (7.1 ± 1.0 W/D ratio and 262.42 ± 24.67 r.f.u./g, respectively). Curcumin prophylaxis significantly attenuated the upregulation of NF-κB (p < 0.001), thereby leading to concomitant downregulation of pro-inflammatory cytokine levels (↓IL-1, IL-2, IL-18 and TNF-α), cell adhesion molecules (↓P-selectin and E-selectin) and increased anti-inflammatory cytokine (↑IL-10). Curcumin stabilized the brain HIF-1α levels followed by maintaining VEGF levels along with upregulated Na⁺/K⁺-ATPase and ENaC levels (p < 0.001) under hypoxia. Curcumin restored the brain ZO-1, JAMC, claudin 4 and claudin 5 levels (p < 0.001) under hypoxia. Histopathological observations revealed the absence of edema and inflammation in the brain of rats supplemented with curcumin.

Conclusions

These results indicate that curcumin is a potent drug in amelioration of HACE as it effectively attenuated inflammation as well as fluid influx by maintaining the tight junction proteins integrity with increased ion channels expression in the brain of rats under hypoxia.

Seminal plasma induces global transcriptomic changes associated with cell migration, proliferation and viability in endometrial epithelial cells and stromal fibroblasts

STUDY QUESTION

How does seminal plasma (SP) affect the transcriptome of human primary endometrial epithelial cells (eEC) and stromal fibroblasts (eSF)?

SUMMARY ANSWER

Exposure of eEC and eSF to SP in vitro increases expression of genes and secreted proteins associated with cellular migration, proliferation, viability and inhibition of cell death.

WHAT IS KNOWN ALREADY

Studies in both humans and animals suggest that SP can access and induce physiological changes in the upper female reproductive tract (FRT), which may participate in promoting reproductive success.

STUDY DESIGN, SIZE, DURATION

This is a cross sectional study involving control samples versus treatment. SP (pooled from twenty donors) was first tested for dose- and time-dependent cytotoxic effects on eEC and eSF (n = 4). As exposure of eEC or eSF to 1% SP for 6 h proved to be non-toxic, a second set of eEC/eSF samples (n = 4) was treated under these conditions for transcriptome, protein and functional analysis. With a third set of samples (n = 3), we further compared the transcriptional response of the cells to SP versus fresh semen.

PARTICIPANTS/MATERIALS, SETTING, METHODS

eEC and eSF were isolated from endometrial biopsies from women of reproductive age undergoing benign gynecologic procedures and maintained in vitro. RNA was isolated and processed for microarray studies to analyze global transcriptomic changes. Secreted factors in conditioned media from SP-treated cells were analyzed by Luminex and for the ability to stimulate migration of CD14+ monocytes and CD4+ T cells.

MAIN RESULTS AND THE ROLE OF CHANCE

Pathway identifications were determined using the Z-scoring system in Ingenuity Pathways Analysis (Z scores ≥|1.5|). SP induced transcriptomic changes (P < 0.05) associated with promoting leukocyte and endothelial cell recruitment, and proliferation of eEC and eSF. Cell viability pathways were induced, while those associated with cell death were suppressed (P < 0.05). SP and fresh semen induced similar sets of pathways, suggesting that SP can model the signaling effects of semen in the endometrium. SP also induced secretion of pro-inflammatory and pro-chemotactic cytokines, as well as pro-angiogenic and proliferative growth factors (P < 0.05) in both eEC and eSF. Finally, functional assays revealed that conditioned media from SP-treated eEC and eSF significantly increased (P < 0.05) chemotaxis of CD14+ monocytes and CD4+ T cells.

LIMITATIONS, REASONS FOR CAUTION

This study is limited to in vitro analyses of the effects of SP on endometrial cells. In addition, the measured response to SP was conducted in the absence of the ovarian hormones estradiol and progesterone, as well as epithelial-stromal paracrine signaling. While this study focused on establishing the baseline cellular response of endometrial cells to SP, future work should assess how hormone signaling in the presence of appropriate paracrine interactions affects SP-induced genes in these cells.

WIDER IMPLICATIONS OF THE FINDINGS

The results of this study support previous findings that SP and semen contain bioactive factors capable of eliciting chemotactic responses in the uterus, which can lead to recruitment of leukocytes to the endometrium. Future directions will explore if similar changes in gene expression do indeed occur after coitus in vivo, and how the signaling cascades initiated by SP in the endometrium can affect reproductive success, female reproductive health and susceptibility to sexually transmitted diseases. The gene list provided by the transcriptome analysis reported here should prove a valuable resource for understanding the response of the upper FRT to SP exposure.

STUDY FUNDING/COMPETING INTEREST(S)

This project was supported by NIH AI083050-04 (W.C.G./L.C.G.); NIH U54HD 055764 (L.C.G.); NIH 1F32HD074423-02 (J.C.C.); DOD W81XWH-11-1-0562 (W.C.G.); NIH 5K12-DK083021-04, NIH 1K99AI104262-01A1, The UCSF Hellman Award (N.R.R.). The authors have nothing to disclose.

Assessment methods for angiogenesis and current approaches for its quantification

Angiogenesis is a physiological process which describes the development of new blood vessels from the existing vessels. It is a common and the most important process in the formation and development of blood vessels, so it is supportive in the healing of wounds and granulation of tissues. The different assays for the evaluation of angiogenesis have been described with distinct advantages and some limitations. In order to develop angiogenic and antiangiogenic techniques, continuous efforts have been resulted to give animal models for more quantitative analysis of angiogenesis. Most of the studies on angiogenic inducers and inhibitors rely on various models, both in vitro, in vivo and in ova, as indicators of efficacy. The angiogenesis assays are very much helpful to test efficacy of both pro- and anti- angiogenic agents. The development of non-invasive procedures for quantification of angiogenesis will facilitate this process significantly. The main objective of this review article is to focus on the novel and existing methods of angiogenesis and their quantification techniques. These findings will be helpful to establish the most convenient methods for the detection, quantification of angiogenesis and to develop a novel, well tolerated and cost effective anti-angiogenic treatment in the near future.

The adventitia: Essential role in pulmonary vascular remodeling

A rapidly emerging concept is that the vascular adventitia acts as a biological processing center for the retrieval, integration, storage, and release of key regulators of vessel wall function. It is the most complex compartment of the vessel wall and comprises a variety of cells including fibroblasts, immunomodulatory cells, resident progenitor cells, vasa vasorum endothelial cells, and adrenergic nerves. In response to vascular stress or injury, resident adventitial cells are often the first to be activated and reprogrammed to then influence tone and structure of the vessel wall. Experimental data indicate that the adventitial fibroblast, the most abundant cellular constituent of adventitia, is a critical regulator of vascular wall function. In response to vascular stresses such as overdistension, hypoxia, or infection, the adventitial fibroblast is activated and undergoes phenotypic changes that include proliferation, differentiation, and production of extracellular matrix proteins and adhesion molecules, release of reactive oxygen species, chemokines, cytokines, growth factors, and metalloproteinases that, collectively, affect medial smooth muscle cell tone and growth directly and that stimulate recruitment and retention of circulating inflammatory and progenitor cells to the vessel wall. Resident dendritic cells also participate in "sensing" vascular stress and actively communicate with fibroblasts and progenitor cells to simulate repair processes that involve expansion of the vasa vasorum, which acts as a conduit for further delivery of inflammatory/progenitor cells. This review presents the current evidence demonstrating that the adventitia acts as a key regulator of pulmonary vascular wall function and structure from the "outside in."

The adventitia: essential regulator of vascular wall structure and function

The vascular adventitia acts as a biological processing center for the retrieval, integration, storage, and release of key regulators of vessel wall function. It is the most complex compartment of the vessel wall and is composed of a variety of cells, including fibroblasts, immunomodulatory cells (dendritic cells and macrophages), progenitor cells, vasa vasorum endothelial cells and pericytes, and adrenergic nerves. In response to vascular stress or injury, resident adventitial cells are often the first to be activated and reprogrammed to influence the tone and structure of the vessel wall; to initiate and perpetuate chronic vascular inflammation; and to stimulate expansion of the vasa vasorum, which can act as a conduit for continued inflammatory and progenitor cell delivery to the vessel wall. This review presents the current evidence demonstrating that the adventitia acts as a key regulator of vascular wall function and structure from the outside in.

Molecular and functional aspects of menstruation in the macaque

Much of our understanding of the molecular control of menstruation arises from laboratory models that experimentally recapitulate some, but not all, aspects of uterine bleeding observed in women. These models include: in vitro culture of endometrial explants or isolated endometrial cells, transplantation of human endometrial tissue into immunodeficient mice and the induction of endometrial breakdown in appropriately pretreated mice. Each of these models has contributed to our understanding of molecular and cellular mechanisms of menstruation, but nonhuman primates, especially macaques, are the animal model of choice for evaluating therapies for menstrual disorders. In this chapter we review some basic aspects of menstruation, with special emphasis on the macaque model and its relevance to the clinical issues of irregular and heavy menstrual bleeding (HMB).

Steroid regulation of menstrual bleeding and endometrial repair

The ovarian steroid hormones progesterone and estradiol are well established regulators of human endometrial function. However, more recent evidence suggests that androgens and locally generated steroids, such as the glucocorticoids, also have a significant impact on endometrial breakdown and repair. The temporal and spatial pattern of steroid receptor presence in endometrial cells has a significant impact on the endometrial response to steroids. Furthermore, regulation of steroid receptor function by modulatory proteins further refines local responses. This review focuses on steroid regulation of endometrial function during the luteo-follicular transition with a focus on menstruation and endometrial repair.

Targeting the adventitial microenvironment in pulmonary hypertension: A potential approach to therapy that considers epigenetic change

Experimental data indicate that the adventitial compartment of blood vessels, in both the pulmonary and systemic circulations, like the connective tissue stroma in tissues throughout the body, is a critical regulator of vessel wall function in health and disease. It is clear that adventitial cells, and in particular the adventitial fibroblast, are activated early following vascular injury, and play essential roles in regulating vascular wall structure and function through production of chemokines, cytokines, growth factors, and reactive oxygen species (ROS). The recognition of the ability of these cells to generate and maintain inflammatory responses within the vessel wall provides insight into why vascular inflammatory responses, in certain situations, fail to resolve. It is also clear that the activated adventitial fibroblast plays an important role in regulating vasa vasorum growth, which can contribute to ongoing vascular remodeling by acting as a conduit for delivery of inflammatory and progenitor cells. These functions of the fibroblast clearly support the idea that targeting chemokine, cytokine, adhesion molecule, and growth factor production in activated fibroblasts could be helpful in abrogating vascular inflammatory responses and thus in ameliorating vascular disease. Further, the recent observations that fibroblasts in vascular and fibrotic diseases may maintain their activated state through epigenetic alterations in key inflammatory and pro-fibrotic genes suggests that current therapies used to treat pulmonary hypertension may not be sufficient to induce apoptosis or to inhibit key inflammatory signaling pathways in these fibroblasts. New therapies targeted at reversing changes in the acetylation or methylation status of key transcriptional networks may be needed. At present, therapies specifically targeting abnormalities of histone deacytelase (HDAC) activity in fibroblast-like cells appear to hold promise.

The regulation of vascular endothelial growth factor by hypoxia and prostaglandin F₂α during human endometrial repair

CONTEXT

The human endometrium has an exceptional capacity for repeated repair after menses, but its regulation remains undefined. Premenstrually, progesterone levels fall and prostaglandin (PG) F₂α synthesis increases, causing spiral arteriole constriction. We hypothesized that progesterone withdrawal, PGF₂α, and hypoxia increase vascular endothelial growth factor (VEGF), an endometrial repair factor.

DESIGN AND RESULTS

Endometrial biopsies were collected (n = 47) with ethical approval and consent. VEGF mRNA, quantified by quantitative RT-PCR, was increased during menstruation (P < 0.01).VEGF protein was maximally secreted from proliferative endometrial explants. Treatment of an endometrial epithelial cell line and primary human endometrial stromal cells with 100 nm PGF₂α or hypoxia (0.5% O₂) resulted in significant increases in VEGF mRNA and protein. VEGF was maximal when cells were cotreated with PGF(2α) and hypoxia simultaneously (P < 0.05-0.001). Secretory-phase endometrial explants also showed an increase in VEGF with cotreatment (P < 0.05). However, proliferative-phase explants showed no increase in VEGF on treatment with PGF₂α and/or hypoxia. Proliferative tissue was induced to increase VEGF mRNA expression when exposed to progesterone and its withdrawal in vitro but only in the presence of hypoxia and PG. Hypoxia-inducible factor-1α (HIF-1α) silencing with RNA interference suppressed hypoxia-induced VEGF expression in endometrial cells but did not alter PGF₂α-induced VEGF expression.

CONCLUSIONS

Endometrial VEGF is increased at the time of endometrial repair. Progesterone withdrawal, PGF₂α, and hypoxia are necessary for this perimenstrual VEGF expression. Hypoxia acts via HIF-1α to increase VEGF, whereas PGF₂α acts in a HIF-1α-independent manner. Hence, two pathways regulate the expression of VEGF during endometrial repair.

Decidualized human endometrial stromal cells mediate hemostasis, angiogenesis, and abnormal uterine bleeding

Factor VII binds trans-membrane tissue factor to initiate hemostasis by forming thrombin. Tissue factor expression is enhanced in decidualized human endometrial stromal cells during the luteal phase. Long-term progestin only contraceptives elicit: 1) abnormal uterine bleeding from fragile vessels at focal bleeding sites, 2) paradoxically high tissue factor expression at bleeding sites; 3) reduced endometrial blood flow promoting local hypoxia and enhancing reactive oxygen species levels; and 4) aberrant angiogenesis reflecting increased stromal cell-expressed vascular endothelial growth factor, decreased Angiopoietin-1 and increased endothelial cell-expressed Angiopoietin-2. Aberrantly high local vascular permeability enhances circulating factor VII to decidualized stromal cell-expressed tissue factor to generate excess thrombin. Hypoxia-thrombin interactions augment expression of vascular endothelial growth factor and interleukin-8 by stromal cells. Thrombin, vascular endothelial growth factor and interleukin-8 synergistically augment angiogenesis in a milieu of reactive oxygen species-induced endothelial cell activation. The resulting enhanced vessel fragility promotes abnormal uterine bleeding.

Endometrial-peritoneal interactions during endometriotic lesion establishment

The pathophysiology of endometriosis remains unclear but involves a complex interaction between ectopic endometrium and host peritoneal tissues. We hypothesized that disruption of this interaction would suppress endometriotic lesion formation. We hoped to delineate the molecular and cellular dialogue between ectopic human endometrium and peritoneal tissues in nude mice as a first step toward testing this hypothesis. Human endometrium was xenografted into nude mice, and the resulting lesions were analyzed using microarrays. A novel technique was developed that unambiguously determined whether RNA transcripts identified via microarray analyses originated from human cells (endometrium) or mouse cells (mesothelium). Four key pathways (ubiquitin/proteasome, inflammation, tissue remodeling/repair, and ras-mediated oncogenesis) were revealed, demonstrating communication between host mesothelial cells and ectopic endometrium. Morphometric analysis of nude mouse lesions confirmed that necrosis, inflammation, healing and repair, and cell proliferation occurred during xenograft development. These processes were entirely consistent with the molecular networks revealed by the microarray data. The transcripts detected in the xenografts overlapped with differentially expressed transcripts in a comparison between paired eutopic and ectopic endometria from human endometriotic patients. For the first time, components of the interaction between ectopic endometrium and peritoneal stromal tissues are revealed. Targeted disruption of this dialogue is likely to inhibit endometriotic tissue formation and may prove to be an effective therapeutic strategy for endometriosis.

VEGF blockade inhibits angiogenesis and reepithelialization of endometrium

Despite extensive literature on vascular endothelial growth factor (VEGF) expression and regulation by steroid hormones, the lack of clear understanding of the mechanisms of angiogenesis in the endometrium is a major limitation for use of antiangiogenic therapy targeting endometrial vessels. In the current work, we used the rhesus macaque as a primate model and the decidualized mouse uterus as a murine model to examine angiogenesis during endometrial breakdown and regeneration. We found that blockade of VEGF action with VEGF Trap, a potent VEGF blocker, completely inhibited neovascularization during endometrial regeneration in both models but had no marked effect on preexisting or newly formed vessels, suggesting that VEGF is essential for neoangiogenesis but not survival of mature vessels in this vascular bed. Blockade of VEGF also blocked reepithelialization in both the postmenstrual endometrium and the mouse uterus after decidual breakdown, evidence that VEGF has pleiotropic effects in the endometrium. In vitro studies with a scratch wound assay showed that the migration of luminal epithelial cells during repair involved signaling through VEGF receptor 2-neuropilin 1 (VEGFR2-NP1) receptors on endometrial stromal cells. The leading front of tissue growth during endometrial repair was strongly hypoxic, and this hypoxia was the local stimulus for VEGF expression and angiogenesis in this tissue. In summary, we provide novel experimental data indicating that VEGF is essential for endometrial neoangiogenesis during postmenstrual/postpartum repair.

Pulmonary artery adventitial fibroblasts cooperate with vasa vasorum endothelial cells to regulate vasa vasorum neovascularization: a process mediated by hypoxia and endothelin-1

The precise cellular and molecular mechanisms regulating adventitial vasa vasorum neovascularization, which occurs in the pulmonary arterial circulation in response to hypoxia, remain unknown. Here, using a technique to isolate and culture adventitial fibroblasts (AdvFBs) and vasa vasorum endothelial cells (VVECs) from the adventitia of pulmonary arteries, we report that hypoxia-activated pulmonary artery AdvFBs exhibited pro-angiogenic properties and influenced the angiogenic phenotype of VVEC, in a process of cell-cell communication involving endothelin-1 (ET-1). We demonstrated that AdvFBs, either via co-culture or conditioned media, stimulated VVEC proliferation and augmented the self-assembly and integrity of cord-like networks that formed when VVECs where cultured on Matrigel. In addition, hypoxia-activated AdvFBs produced ET-1, suggesting a paracrine role for this pro-angiogenic molecule in these processes. When co-cultured on Matrigel, AdvFBs and VVECs self-assembled into heterotypic cord-like networks, a process augmented by hypoxia but attenuated by either selective endothelin receptor antagonists or oligonucleotides targeting prepro-ET-1 mRNA. From these observations, we propose that hypoxia-activated AdvFBs exhibit pro-angiogenic properties and, as such, communicate with VVECs, in a process involving ET-1, to regulate vasa vasorum neovascularization occurring in the adventitia of pulmonary arteries in response to chronic hypoxia.

Regulation of human endometrial function: mechanisms relevant to uterine bleeding

This review focuses on the complex events that occur in the endometrium after progesterone is withdrawn (or blocked) and menstrual bleeding ensues. A detailed understanding of these local mechanisms will enhance our knowledge of disturbed endometrial/uterine function--including problems with excessively heavy menstrual bleeding, endometriosis and breakthrough bleeding with progestin only contraception. The development of novel strategies to manage these clinically significant problems depends on such new understanding as does the development of new contraceptives which avoid the endometrial side effect of breakthrough bleeding.

The relationship between transplacental O2 diffusion and placental expression of PlGF, VEGF and their receptors in a placental insufficiency model of fetal growth restriction

Placental growth factor (PlGF) and vascular endothelial growth factor (VEGF) are involved in placental angiogenesis through interactions with the VEGFR-1 and VEGFR-2 receptors. The placenta of pregnancies whose outcome is fetal growth restriction (FGR) are characterized by abnormal angiogenic development, classically associated with hypoxia. The present study evaluated the near-term expression of this growth factor family in an ovine model of placental insufficiency-FGR, in relationship to uteroplacental oxygenation. Compared to controls, FGR pregnancies demonstrated a 37% increase in uterine blood flow (FGR vs. control, 610.86+/-48.48 vs. 443.17+/-37.39 ml min(-1) (kg fetus)(-1); P<0.04), which was associated with an increased maternal uterine venous PO2 (58.13+/-1.00 vs. 52.89+/-1.26 mmHg; P<0.02), increased umbilical artery systolic/diastolic ratio (3.90+/-0.33 vs. 2.12+/-0.26, P<0.05), and fetal hypoxia (arterial PO2; 12.79+/-0.97 vs. 18.65+/-1.6 mmHg, P<0.005). Maternal caruncle PlGF mRNA was increased in FGR (P<0.02), while fetal cotyledon VEGF mRNA was reduced (P<0.02). VEGFR-1 mRNA was also reduced in FGR fetal cotyledon (P<0.001) but was not altered in caruncle tissue. Immunoblot analysis of PlGF and VEGF demonstrated single bands at 19,000 and 18,600 Mr, respectively. Caruncle PlGF concentration was increased (P<0.04), while cotyledon VEGF was decreased (P<0.05) in FGR placentae. The data establish that uterine blood flow is not reduced in relationship to metabolic demands in this FGR model and that the transplacental PO2 gradient is increased, maintaining umbilical oxygen uptake per unit of tissue. Furthermore, these data suggest that an increased transplacental gradient of oxygen generates changes in angiogenic growth factors, which may underline the pathophysiology of the post-placental hypoxic FGR.

Abnormal uterine bleeding during progestin-only contraception may result from free radical-induced alterations in angiopoietin expression

Abnormal uterine bleeding is the leading indication for discontinuation of long-term progestin-only contraceptives (LTPOCs). Histological sections of endometria from LTPOC-treated patients display abnormally enlarged blood vessels at bleeding sites. Paradoxically, a trend toward reduced endometrial perfusion in LTPOC users has been reported in these patients. We hypothesized that hypoxia/reperfusion-induced free radical production inhibits the expression of angiopoietin-1 (Ang-1), a vessel stabilizing factor, leaving unopposed the effects of endothelial Ang-2, a vessel-branching and permeability factor. Immunohistochemical studies confirmed selective decreases in stromal cell Ang-1 in LTPOC-exposed endometrium. To indirectly assess whether LTPOC enhances endometrial free radical production, immunostaining was conducted for the phosphorylated form of the stress-activated kinases SAPK/JNK and p38. These kinases were greatly increased in endometria from LTPOC-treated patients. Interestingly, the endothelial cells but not the stromal cells displayed enhanced immunostaining for the phosphorylated mitogen-activated kinase (pMAPK) after LTPOC treatment. To further examine the effects of progestin, hypoxia, and reactive oxygen species (ROS) on the regulation of Ang-1 and Ang-2 as well as the activation of MAPK, SAPK/JNK, and p38 by the relevant cell types, we conducted in vitro studies with cultured human endometrial stromal cells (HESCs) and human endometrial endothelial cells (HEECs). Cultures of HESCs were treated with vehicle control, estradiol (E(2)), or with medroxyprogesterone acetate +/- E(2) under hypoxic and normoxic conditions. Although medroxyprogesterone acetate but not E(2) increased Ang-1 expression, hypoxia greatly decreased Ang-1 protein and mRNA expression. In contrast, HESCs did not appear to express Ang-2 protein or mRNA. Conversely, cultured HEECs did not appear to express Ang-1, but expressed Ang-2, the levels of which were significantly increased by hypoxia. Hypoxia also induced the phosphorylation of SAPK/JNK and p38 in both cultured HESCs and HEECs. Moreover, ROS such as that observed after hypoxia/reperfusion resulted in the activation of SAPK/JNK and p38 in HESCs and HEECs and inhibited Ang-1 in cultured HESCs. These effects could be blocked by oxygen radical scavengers. Consistent with the in vivo studies, MAPK was activated after ROS treatment in HEECs but not in HESCs. Our findings suggest that LTPOC-induced endometrial bleeding occurs as a result of hypoxia/reperfusion-induced free radicals that directly damage vessels and alter the balance of Ang-1 and Ang-2 to produce the characteristic enlarged and permeable vessels that are prone to bleeding.

Cerebral microvascular changes in permeability and tight junctions induced by hypoxia-reoxygenation

Cerebral microvessel endothelial cells that form the blood-brain barrier (BBB) have tight junctions (TJ) that are critical for maintaining brain homeostasis and low permeability. Both integral (claudin-1 and occludin) and membrane-associated zonula occluden-1 and -2 (ZO-1 and ZO-2) proteins combine to form these TJ complexes that are anchored to the cytoskeletal architecture (actin). Disruptions of the BBB have been attributed to hypoxic conditions that occur with ischemic stroke, pathologies of decreased perfusion, and high-altitude exposure. The effects of hypoxia and posthypoxic reoxygenation in cerebral microvasculature and corresponding cellular mechanisms involved in disrupting the BBB remain unclear. This study examined hypoxia and posthypoxic reoxygenation effects on paracellular permeability and changes in actin and TJ proteins using primary bovine brain microvessel endothelial cells (BBMEC). Hypoxia induced a 2.6-fold increase in [(14)C]sucrose, a marker of paracellular permeability. This effect was significantly reduced (~58%) with posthypoxic reoxygenation. After hypoxia and posthypoxic reoxygenation, actin expression was increased (1.4- and 2.3-fold, respectively). Whereas little change was observed in TJ protein expression immediately after hypoxia, a twofold increase in expression was seen with posthypoxic reoxygenation. Furthermore, immunofluorescence studies showed alterations in occludin, ZO-1, and ZO-2 protein localization during hypoxia and posthypoxic reoxygenation that correlate with the observed changes in BBMEC permeability. The results of this study show hypoxia-induced changes in paracellular permeability may be due to perturbation of TJ complexes and that posthypoxic reoxygenation reverses these effects.

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

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