Macrophage- and lymphocyte-subtypes in the endometrium during different phases of the ovarian cycle

An integrated single-cell reference atlas of the human endometrium

The complex and dynamic cellular composition of the human endometrium remains poorly understood. Previous endometrial single-cell atlases profiled few donors and lacked consensus in defining cell types. We introduce the Human Endometrial Cell Atlas (HECA), a high-resolution single-cell reference atlas (313,527 cells) combining published and new endometrial single-cell transcriptomics datasets of 63 women with and without endometriosis. HECA assigns consensus and identifies previously unreported cell types, mapped in situ using spatial transcriptomics and validated using a new independent single-nuclei dataset (312,246 nuclei, 63 donors). In the functionalis, we identify intricate stromal-epithelial cell coordination via transforming growth factor beta (TGFβ) signaling. In the basalis, we define signaling between fibroblasts and an epithelial population expressing progenitor markers. Integration of HECA with large-scale endometriosis genome-wide association study data pinpoints decidualized stromal cells and macrophages as most likely dysregulated in endometriosis. The HECA is a valuable resource for studying endometrial physiology and disorders, and for guiding microphysiological in vitro systems development.

Cyclical endometrial repair and regeneration: Molecular mechanisms, diseases, and therapeutic interventions

The endometrium is a unique human tissue with an extraordinary ability to undergo a hormone-regulated cycle encompassing shedding, bleeding, scarless repair, and regeneration throughout the female reproductive cycle. The cyclical repair and regeneration of the endometrium manifest as changes in endometrial epithelialization, glandular regeneration, and vascularization. The mechanisms encompass inflammation, coagulation, and fibrinolytic system balance. However, specific conditions such as endometriosis or TCRA treatment can disrupt the process of cyclical endometrial repair and regeneration. There is uncertainty about traditional clinical treatments' efficacy and side effects, and finding new therapeutic interventions is essential. Researchers have made substantial progress in the perspective of regenerative medicine toward maintaining cyclical endometrial repair and regeneration in recent years. Such progress encompasses the integration of biomaterials, tissue-engineered scaffolds, stem cell therapies, and 3D printing. This review analyzes the mechanisms, diseases, and interventions associated with cyclical endometrial repair and regeneration. The review discusses the advantages and disadvantages of the regenerative interventions currently employed in clinical practice. Additionally, it highlights the significant advantages of regenerative medicine in this domain. Finally, we review stem cells and biologics among the available interventions in regenerative medicine, providing insights into future therapeutic strategies.

(Not) Home alone: Antigen presenting cell - T Cell communication in barrier tissues

Priming of T cells by antigen presenting cells (APCs) is essential for T cell fate decisions, enabling T cells to migrate to specific tissues to exert their effector functions. Previously, these interactions were mainly explored using blood-derived cells or animal models. With great advances in single cell RNA-sequencing techniques enabling analysis of tissue-derived cells, it has become clear that subsets of APCs are responsible for priming and modulating heterogeneous T cell effector responses in different tissues. This composition of APCs and T cells in tissues is essential for maintaining homeostasis and is known to be skewed in infection and inflammation, leading to pathological T cell responses. This review highlights the commonalities and differences of T cell priming and subsequent effector function in multiple barrier tissues such as the skin, intestine and female reproductive tract. Further, we provide an overview of how this process is altered during tissue-specific infections which are known to cause chronic inflammation and how this knowledge could be harnessed to modify T cell responses in barrier tissue.

What Do the Transcriptome and Proteome of Menstrual Blood-Derived Mesenchymal Stem Cells Tell Us about Endometriosis?

Given the importance of menstrual blood in the pathogenesis of endometriosis and the multifunctional roles of menstrual mesenchymal stem cells (MenSCs) in regenerative medicine, this issue has gained prominence in the scientific community. Moreover, recent reviews highlight how robust the integrated assessment of omics data are for endometriosis. To our knowledge, no study has applied the multi-omics approaches to endometriosis MenSCs. This is a case-control study at a university-affiliated hospital. MenSCs transcriptome and proteome data were obtained by RNA-seq and UHPLC-MS/MS detection. Among the differentially expressed proteins and genes, we emphasize ATF3, ID1, ID3, FOSB, SNAI1, NR4A1, EGR1, LAMC3, and ZFP36 genes and MT2A, TYMP, COL1A1, COL6A2, and NID2 proteins that were already reported in the endometriosis. Our functional enrichment analysis reveals integrated modulating signaling pathways such as epithelial-mesenchymal transition (↑) and PI3K signaling via AKT to mTORC1 (↓ in proteome), mTORC1 signaling, TGF beta signaling, TNFA signaling via NFkB, IL6 STAT3 signaling, and response to hypoxia via HIF1A targets (↑ in transcriptome). Our findings highlight primary changes in the endometriosis MenSCs, suggesting that the chronic inflammatory endometrial microenvironment can modulate these cells, providing opportunities for endometriosis etiopathogenesis. Moreover, they identify challenges for future research leveraging knowledge for regenerative and precision medicine in endometriosis.

Role of macrophages in the immunopathogenesis of adenomyosis

The aim of the research: to study pathophysiological mechanisms of adenomyosis development by determining the role of macrophages in the uterine microenvironment. Materials and methods: a prospective study has been conducted on 35 women. There were 20 (57.1 %) who had adenomyosis of I degree. The control group consisted of 15 (34.3 %) gynecologically healthy women. The patients underwent general clinical, instrumental (ultrasound, hysteroscopy) examinations. Fragments of the uterine wall obtained by hysterorectoscopy were used for morphological study. The method of immunohistochemical determination of CD68+ and CD163+ macrophages was used to analyze the characteristics of phenotypic equivalents of M1 and M2 macrophages in uterine tissue samples. Results: The increase in the number of macrophages in the myometrium of patients with adenomyosis revealed in this study, which is found in large numbers in the areas of infiltration of the stroma of myometrial cells in close association with the perivascular region, can be regarded as the basis of the mechanism for the formation of endometrioid heterotopia. Furthermore, distortion of the CD68/CD163 ratio of macrophages is characterized by proinflammatory shift. Conclusions: The study's main result is an increase in the quantitative indicators of CD68+ macrophages associated with adenomyosis, which indicates an immunopathological process in adenomyosis.

Excess Heme Promotes the Migration and Infiltration of Macrophages in Endometrial Hyperplasia Complicated with Abnormal Uterine Bleeding

In patients, endometrial hyperplasia (EH) is often accompanied by abnormal uterine bleeding (AUB), which is prone to release large amounts of heme. However, the role of excess heme in the migration and infiltration of immune cells in EH complicated by AUB remains unknown. In this study, 45 patients with AUB were divided into three groups: a proliferative phase group (n = 15), a secretory phase group (n = 15) and EH (n = 15). We observed that immune cell subpopulations were significantly different among the three groups, as demonstrated by flow cytometry analysis. Of note, there was a higher infiltration of total immune cells and macrophages in the endometrium of patients with EH. Heme up-regulated the expression of heme oxygenase-1 (HO-1) and nuclear factor erythroid-2-related factor 2 (Nrf2) in endometrial epithelial cells (EECs) in vitro, as well as chemokine (e.g., CCL2, CCL3, CCL5, CXCL8) levels. Additionally, stimulation with heme led to the increased recruitment of THP-1 cells in an indirect EEC-THP-1 co-culture unit. These data suggest that sustained and excessive heme in patients with AUB may recruit macrophages by increasing the levels of several chemokines, contributing to the accumulation and infiltration of macrophages in the endometrium of EH patients, and the key molecules of heme metabolism, HO-1 and Nrf2, are also involved in this regulatory process.

Combinatory effects of current regimens and Guizhi Fuling Wan on the development of endometriosis

OBJECTIVE

Endometriosis, defined as the growth of endometrial glands and stromal cells in a heterotopic location under the cyclic influence of ovarian hormones, is a common gynecological disorder manifested by chronic pelvic pain and infertility. In traditional Chinese medicine, endometriosis is characterized by stagnation of vital energy (qi) and blood stasis. Guizhi Fuling Wan (GFW) was first described in Chinese canonical medicine to treat disorders associated with stagnation of qi and blood stasis, including endometriosis. Therefore, the current study aimed to test the effects of combining GFW with western medicine on the suppression of endometriosis.

MATERIALS AND METHODS

Endometriosis was generated by suturing endometrial tissue on the peritoneal wall of C57BL/6JNarl mice. The mice were subsequently treated with either GFW or current hormonal therapies or in combination for 28 days.

RESULTS

Endometriosis development was inhibited by GFW, Gestrinone, Visanne, GFW + Gestrinone or GFW + medroxyprogesterone acetate (MPA). The expression of intercellular adhesion molecule 1 (ICAM-1) was inhibited by GFW, Gestrinone, MPA, Visanne, GFW + Gestrinone, GFW + MPA and GFW + Visanne. Vascular endothelial growth factor (VEGF) expression was inhibited by GFW, Gestrinone, Visanne, GFW + Gestrinone and GFW + MPA. Both ICAM-1- and VEGF-reducing effects of GFW were attenuated by western medicines. Administration of GFW, MPA, Visanne, GFW + MPA and GFW + Visanne also correspondingly reduced macrophage population in peritoneal fluid. GFW, MPA, Visanne, GFW + MPA and GFW + Visanne enhanced B-cell population in peritoneal fluid.

CONCLUSION

The current study reveals the therapeutic effects of GFW on endometriosis. However, the combination of GFW and current hormonal therapies potentially impedes the efficacy of each individual agent in treating endometriosis.

Stromal Heterogeneity in the Human Proliferative Endometrium-A Single-Cell RNA Sequencing Study

The endometrium undergoes regular regeneration and stromal proliferation as part of the normal menstrual cycle. To better understand cellular interactions driving the mechanisms in endometrial regeneration we employed single-cell RNA sequencing. Endometrial biopsies were obtained during the proliferative phase of the menstrual cycle from healthy fertile women and processed to single-cell suspensions which were submitted for sequencing. In addition to known endometrial cell types, bioinformatic analysis revealed multiple stromal populations suggestive of specific stromal niches with the ability to control inflammation and extracellular matrix composition. Ten different stromal cells and two pericyte subsets were identified. Applying different R packages (Seurat, SingleR, Velocyto) we established cell cluster diversity and cell lineage/trajectory, while using external data to validate our findings. By understanding healthy regeneration in the described stromal compartments, we aim to identify points of further investigation and possible targets for novel therapy development for benign gynecological disorders affecting endometrial regeneration and proliferation such as endometriosis and Asherman’s syndrome.

Endometriosis and Cancer: Exploring the Role of Macrophages

Endometriosis and cancer have much in common, notably their burgeoning of cells in hypoxic milieus, their invasiveness, and their capacity to trigger remodeling, vascularization, and innervation of other tissues. An important role in these processes is played by permissive microenvironments inhabited by a variety of stromal and immune cells, including macrophages. Remarkable phenotypical plasticity of macrophages makes them a promising therapeutic target; some key issues are the range of macrophage phenotypes characteristic of a particular pathology and the possible manners of its modulation. In both endometriosis and cancer, macrophages guard the lesions from immune surveillance while promoting pathological cell growth, invasion, and metastasis. This review article focuses on a comparative analysis of macrophage behaviors in endometriosis and cancer. We also highlight recent reports on the experimental modulation of macrophage phenotypes in preclinical models of endometriosis and cancer.

Immune Tolerance of the Human Decidua

The endometrium is necessary for implantation, complete development of the placenta, and a successful pregnancy. The endometrium undergoes repeated cycles of proliferation, decidualization (differentiation), and shedding during each menstrual cycle. The endometrium—including stromal, epithelial, vascular endothelial, and immune cells—is both functionally and morphologically altered in response to progesterone, causing changes in the number and types of immune cells. Immune cells make up half of the total number of endometrial cells during implantation and menstruation. Surprisingly, immune tolerant cells in the endometrium (uterine natural killer cells, T cells, and macrophages) have two conflicting functions: to protect the body by eliminating pathogenic microorganisms and other pathogens and to foster immunological change to tolerate the embryo during pregnancy. One of the key molecules involved in this control is the cytokine interleukin-15 (IL-15), which is secreted by endometrial stromal cells. Recently, it has been reported that IL-15 is directly regulated by the transcription factor heart- and neural crest derivatives-expressed protein 2 in endometrial stromal cells. In this review, we outline the significance of the endometrium and immune cell population during menstruation and early pregnancy and describe the factors involved in immune tolerance and their involvement in the establishment and maintenance of pregnancy.

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.

Immune responses in the human female reproductive tract

Mucosal surfaces are key interfaces between the host and its environment, but also constitute ports of entry for numerous pathogens. The gut and lung mucosae act as points of nutrient and gas exchange, respectively, but the physiological purpose of the female reproductive tract (FRT) is to allow implantation and development of the fetus. Our understanding of immune responses in the FRT has traditionally lagged behind our grasp of the situation at other mucosal sites, but recently reproductive immunologists have begun to make rapid progress in this challenging area. Here, we review current knowledge of immune responses in the human FRT and their heterogeneity within and between compartments. In the commensal-rich vagina, the immune system must allow the growth of beneficial microbes, whereas the key challenge in the uterus is allowing the growth of the semi-allogeneic fetus. In both compartments, these objectives must be balanced with the need to eliminate pathogens. Our developing understanding of immune responses in the FRT will help us develop interventions to prevent the spread of sexually transmitted diseases and to improve outcomes of pregnancy for mothers and babies.

Uterine Immunity and Microbiota: A Shifting Paradigm

The female reproductive tract harbors distinct microbial communities, as in the vagina, cervical canal, uterus, and fallopian tubes. The nature of the vaginal microbiota is well-known; in contrast, the upper reproductive tract remains largely unexplored. Alteration in the uterine microbiota, which is dependent on the nutrients and hormones available to the uterus, is likely to play an important role in uterine-related diseases such as hysteromyoma, adenomyosis, and endometriosis. Uterine mucosa is an important tissue barrier whose main function is to offer protection against pathogens and other toxic factors, while maintaining a symbiotic relationship with commensal microbes. These characteristics are shared by all the mucosal tissues; however, the uterine mucosa is unique since it changes cyclically during the menstrual cycle as well as pregnancy. The immune system, besides its role in the defense process, plays crucial roles in reproduction as it ensures local immune tolerance to fetal/paternal antigens, trophoblast invasion, and vascular remodeling. The human endometrium contains a conspicuous number of immune cells, mainly Natural Killers (NK) cells, which are phenotypically distinct from peripheral cytotoxic NK, cells and macrophages. The endometrium also contains few lymphoid aggregates comprising B cell and CD8⁺ T cells. The number and the phenotype of these cells change during the menstrual cycle. It has become evident in recent years that the immune cell phenotype and function can be influenced by microbiota. Immune cells can sense the presence of microbes through their pattern recognition receptors, setting up host-microbe interaction. The microbiota exerts an appropriately controlled defense mechanism by competing for nutrients and mucosal space with pathogens. It has recently been considered that uterus is a non-sterile compartment since it seems to possess its own microbiota. There has been an increasing interest in characterizing the nature of microbial colonization within the uterus and its apparent impact on fertility and pregnancy. This review will examine the potential relationship between the uterine microbiota and the immune cells present in the local environment.

The endometrial immune environment of women with endometriosis

BACKGROUND

Endometriosis, a common oestrogen-dependent inflammatory disorder in women of reproductive age, is characterized by endometrial-like tissue outside its normal location in the uterus, which causes pelvic scarring, pain and infertility. While its pathogenesis is poorly understood, the immune system (systemically and locally in endometrium, pelvic endometriotic lesions and peritoneal fluid) is believed to play a central role in its aetiology, pathophysiology and associated morbidities of pain, infertility and poor pregnancy outcomes. However, immune cell populations within the endometrium of women with the disease have had incomplete phenotyping, thereby limiting insight into their roles in this disorder.

OBJECTIVE AND RATIONALE

The objective herein was to determine reproducible and consistent findings regarding specific immune cell populations and their abundance, steroid hormone responsiveness, functionality, activation states, and markers, locally and systemically in women with and without endometriosis.

SEARCH METHODS

A comprehensive English language PubMed, Medline and Google Scholar search was conducted with key search terms that included endometriosis, inflammation, human eutopic/ectopic endometrium, immune cells, immune population, immune system, macrophages, dendritic cells (DC), natural killer cells, mast cells, eosinophils, neutrophils, B cells and T cells.

OUTCOMES

In women with endometriosis compared to those without endometriosis, some endometrial immune cells display similar cycle-phase variation, whereas macrophages (Mø), immature DC and regulatory T cells behave differently. A pro-inflammatory Mø1 phenotype versus anti-inflammatory Mø2 phenotype predominates and natural killer cells display abnormal activity in endometrium of women with the disease. Conflicting data largely derive from small studies, variably defined hormonal milieu and different experimental approaches and technologies.

WIDER IMPLICATIONS

Phenotyping immune cell subtypes is essential to determine the role of the endometrial immune niche in pregnancy and endometrial homeostasis normally and in women with poor reproductive history and can facilitate development of innovative diagnostics and therapeutics for associated symptoms and compromised reproductive outcomes.

Tissue distribution of some immune cells in bovine reproductive tract during follicular and luteal phase

More recent studies indicate that immune cells which secrete their secretory products or cytokines play an important role in reproductive system. In our study, immune cell populations (CD8⁺ T lymphocytes, CD68⁺ macrophages, plasma cells, siderophages, eosinophils) and expression of major histocompatibility complex (MHC) class I and class II were examined in female reproductive tract during follicular (n = 13) and luteal phase (n = 10). Plasma cells and eosinophil granulocytes are present in few numbers in luminal epithelium, but abundant in longitudinal muscle layer of uterus, whereas siderophages are the dominant cell type in stroma. Moreover, MHC-I and -II⁺ cells are expressed by individual cells in organ layers, while CD8⁺ T cells and CD68⁺ macrophages are dominant in epithelium and muscle layer, respectively. In conclusion, we did not found significant changes in immune cells according to follicular and luteal phases, but localization and numbers in each organ have changed according to both organ and layers. These results indicate that these factors may play a crucial role not only to generate an immune response but also to have a role in regulation of physiological functions in female reproductive organs.

Cortisol regulates the paracrine action of macrophages by inducing vasoactive gene expression in endometrial cells

The human endometrium undergoes inflammation and tissue repair during menstruation. We hypothesized that the local availability of bioactive glucocorticoids plays an important role in immune cell-vascular cell interactions in endometrium during tissue repair at menstruation, acting either directly or indirectly via tissue resident macrophages. We sought to determine whether endometrial macrophages are direct targets for glucocorticoids; whether cortisol-treated macrophages have a paracrine effect on angiogenic gene expression by endometrial endothelial cells; and whether endometrial macrophages express angiogenic factors. Human endometrium (n = 41) was collected with ethical approval and subject consent. Donor peripheral blood monocyte-derived macrophages were treated with estradiol, progesterone, or cortisol. The effect of peripheral blood monocyte-derived macrophage secretory products on the expression of angiogenic RNAs by endothelial cells was examined. Immunofluorescence was used to examine localization in macrophages and other endometrial cell types across the menstrual cycle. Endometrial macrophages express the glucocorticoid receptor. In vitro culture with supernatants from cortisol-treated peripheral blood monocyte-derived macrophages resulted in altered endometrial endothelial cell expression of the angiogenic genes, CXCL2, CXCL8, CTGF, and VEGFC These data highlight the importance of local cortisol in regulating paracrine actions of macrophages in the endometrium. CXCL2 and CXCL8 were detected in endometrial macrophages in situ. The expression of these factors was highest in the endometrium during the menstrual phase, consistent with these factors having a role in endometrial repair. Our data have indicated that activation of macrophages with glucocorticoids might have paracrine effects by increasing angiogenic factor expression by endometrial endothelial cells. This might reflect possible roles for macrophages in endometrial repair of the vascular bed after menstruation.

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.

Immune cells in the female reproductive tract

The female reproductive tract has two main functions: protection against microbial challenge and maintenance of pregnancy to term. The upper reproductive tract comprises the fallopian tubes and the uterus, including the endocervix, and the lower tract consists of the ectocervix and the vagina. Immune cells residing in the reproductive tract play contradictory roles: they maintain immunity against vaginal pathogens in the lower tract and establish immune tolerance for sperm and an embryo/fetus in the upper tract. The immune system is significantly influenced by sex steroid hormones, although leukocytes in the reproductive tract lack receptors for estrogen and progesterone. The leukocytes in the reproductive tract are distributed in either an aggregated or a dispersed form in the epithelial layer, lamina propria, and stroma. Even though immune cells are differentially distributed in each organ of the reproductive tract, the predominant immune cells are T cells, macrophages/dendritic cells, natural killer (NK) cells, neutrophils, and mast cells. B cells are rare in the female reproductive tract. NK cells in the endometrium significantly expand in the late secretory phase and further increase their number during early pregnancy. It is evident that NK cells and regulatory T (Treg) cells are extremely important in decidual angiogenesis, trophoblast migration, and immune tolerance during pregnancy. Dysregulation of endometrial/decidual immune cells is strongly related to infertility, miscarriage, and other obstetric complications. Understanding the immune system of the female reproductive tract will significantly contribute to women's health and to success in pregnancy.

Matrix metalloproteinase-27 is expressed in CD163+/CD206+ M2 macrophages in the cycling human endometrium and in superficial endometriotic lesions

Matrix metalloproteinases (MMPs) are key enzymes involved in extracellular matrix remodelling. In the human endometrium, the expression and activity of several MMPs are maximal during the menstrual phase. Moreover, MMPs are thought to be involved in the pathogenesis of endometriosis and cancers, in particular with invasion and metastasis. We recently reported that MMP-27 is a unique MMP with an intracellular retention motif. We investigated the expression and cellular localization of MMP-27 in the cycling human endometrium and in endometriotic lesions. MMP-27 mRNA was detected throughout the menstrual cycle. Despite large interpatient variations, mRNA levels increased from the proliferative to the secretory phase, to peak during the menstrual phase. MMP-27 was immunolocalized in large isolated cells scattered throughout the stroma and around blood vessels: these cells were most abundant at menstruation and were identified by immunofluorescence as CD45(+), CD163(+) and CD206(+) macrophages. CD163(+) macrophages were also abundant in endometriotic lesions, but showed different patterns in ovarian or peritoneal endometriotic lesions (co-labelling for CD206 and MMP-27) and rectovaginal lesions (no co-labelling). In conclusion, MMP-27 is expressed in a subset of endometrial macrophages related to menstruation and in ovarian and peritoneal endometriotic lesions.

The importance of the macrophage within the human endometrium

The human endometrium is exposed to cyclical fluctuations of ovarian-derived sex steroids resulting in proliferation, differentiation (decidualization), and menstruation. An influx of leukocytes (up to 15% macrophages) occurs during the latter stages of the menstrual cycle, including menses. We believe the endometrial macrophage is likely to play an important role during the menstrual cycle, especially in the context of tissue degradation (menstruation), which requires regulated repair, regeneration, and phagocytic clearance of endometrial tissue debris to re-establish tissue integrity in preparation for fertility. The phenotype and regulation of the macrophage within the endometrium during the menstrual cycle and interactions with other cell types that constitute the endometrium are currently unknown and are important areas of study. Understanding the many roles of the endometrial macrophage is crucial to our body of knowledge concerning functionality of the endometrium as well as to our understanding of disorders of the menstrual cycle, which have major impacts on the health and well-being of women.

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.

A subset of human uterine endometrial macrophages is alternatively activated

PROBLEM

Human uterine macrophages must maintain an environment hospitable to implantation and pregnancy and simultaneously provide protection against pathogens. Although macrophages comprise a significant portion of leukocytes within the uterine endometrium, the activation profile and functional response of these cells to endotoxin are unknown.

METHOD OF STUDY

Flow cytometric analysis of surface receptors and intracellular markers expressed by macrophages isolated from human endometria was performed. Uterine macrophages were stimulated with LPS. Cytokines, chemokines, and growth factors expressed by these cells were analyzed using Bio-Plex analysis.

RESULTS

CD163(high) human endometrial macrophages constitutively secrete both pro- and anti-inflammatory cytokines as well as pro-angiogenic factors and secretion of these factors is LPS-inducible.

CONCLUSION

A major population of human uterine macrophages is alternatively activated. These cells secrete factors in response to LPS that are involved in the activation of immune responses and tissue homeostasis.

Macrophages regulate expression of α1,2-fucosyltransferase genes in human endometrial epithelial cells

The epithelial cell surface of the endometrium undergoes substantial biochemical changes to allow embryo attachment and implantation in early pregnancy. We hypothesized that tissue macrophages influence these events to promote uterine receptivity. To investigate the role of macrophages in regulating epithelial cell expression of genes linked to glycan-mediated embryo adhesion, Ishikawa, RL95-2 and HEC1A endometrial epithelial cells were cultured alone or with unactivated or lipopolysaccharide-activated monocytic U937 cells, separated using transwell inserts. Expression of mRNAs encoding two α1,2-fucosyltransferases (FUT1, FUT2) was increased in all three epithelial cell lines following co-culture with U937 cells, and was associated with increased fucosylation of cell surface glycoproteins detected using lectins from Ulex europaeus (UEA-1) and Dolichos biflorus (DBA). FUT1 induction by U937 cells also occurred in primary endometrial epithelial cells collected in luteal but not proliferative phase. Activation of the interleukin-6 (IL6)/leukemia inhibitory factor (LIF) cytokine signaling pathway with phosphorylation of STAT3 and elevated SOCS3 mRNA expression was evident in epithelial cells stimulated by U937 co-culture. Several recombinant macrophage-secreted cytokines exerted stimulatory or inhibitory effects on FUT1 and FUT2 mRNA expression, and the macrophage-derived cytokine LIF partially replicated the effects of U937 cells on both FUT1 and FUT2 expression and UEA-1 and DBA lectin reactivity in Ishikawa cells. These results suggest that macrophage-derived factors including LIF might facilitate development of an implantation-receptive endometrium by regulating surface glycan structures in epithelial cells. Abnormal phenotypes or altered abundance of uterine macrophages could contribute to the pathophysiology of primary unexplained infertility in women.

The presence and regulation of connective tissue growth factor in the human endometrium

BACKGROUND

The human endometrium efficiently repairs each month after menstruation. The mechanisms involved in this repair process remain undefined. Aberrations in endometrial repair may lead to the common disorder of heavy menstrual bleeding. We hypothesized that connective tissue growth factor (CTGF) is increased at the time of endometrial repair post-menses and that this increase is regulated by prostaglandins (PGs) and hypoxic conditions present during menstruation.

METHODS AND RESULTS

Examination of 41 endometrial biopsies from 5 stages of the menstrual cycle revealed maximal CTGF mRNA expression (using quantitative RT-PCR) at menstruation and peak protein levels during the proliferative phase. CTGF was immunolocalized to epithelial and stromal cells, with intense staining of occasional stromal cells during the proliferative phase. Dual immunohistochemistry identified these cells as macrophages. Treatment of endometrial epithelial cells with 100 nM PGE(2), PGF(2α) or hypoxia (0.5% O(2)) revealed a significant increase in CTGF mRNA expression (P < 0.01 for all, versus vehicle control). Cells treated simultaneously with PGE(2) and hypoxia revealed a synergistic increase in CTGF expression (P < 0.05 versus PGE(2) or hypoxia alone) and maximal secreted CTGF protein levels (P < 0.05 versus control).

CONCLUSIONS

CTGF is increased in the human endometrium at the time of endometrial repair post-menses. The increase in CTGF may be mediated by PG production and the transient hypoxic episode observed in the endometrium at menstruation.

Coronary artery disease in aging women: a menopause of endothelial progenitor cells?

The cardiovascular protection provided to women during the reproductive age and the unique angiogenic properties of the female reproductive system provide insights into the complex regulatory network of female sex hormones, angiogenic growth factors, and stem cell regulatory molecules. The intricate and interwoven endometrial physiology of the female menstrual cycle shows that in order to harness the physiologic cardioprotection provided by nature to women of reproductive age, for better cardiovascular therapies in postmenopausal women and the population in general, a coherent and systematic approach is needed.

Inflammatory pathways in endometrial disorders

Complex interactions between the endocrine and immune systems govern the key endometrial events of implantation and menstruation. In contrast to other tissue sites, cyclical endometrial inflammation is physiological. However, dysregulation of this inflammatory response can lead to endometrial disorders. This review examines the inflammatory processes occurring in the normal endometrium during menstruation and implantation, highlighting recent advances in our understanding and gaps in current knowledge. Subsequently, the role of inflammatory pathways in the pathology of various common endometrial conditions is discussed, including heavy menstrual bleeding, dysmenorrhoea (painful periods), uterine fibroids, endometriosis and recurrent miscarriage.

Macrophage-derived LIF and IL1B regulate alpha(1,2)fucosyltransferase 2 (Fut2) expression in mouse uterine epithelial cells during early pregnancy

Macrophages accumulate within stromal tissue subjacent to the luminal epithelium in the mouse uterus during early pregnancy after seminal fluid exposure at coitus. To investigate their role in regulating epithelial cell expression of fucosylated structures required for embryo attachment and implantation, fucosyltransferase enzymes Fut1, Fut2 (Enzyme Commission number [EC] 2.4.1.69), and Fut4 (EC 2.4.1.214) and Muc1 and Muc4 mRNAs were quantified by quantitative real-time PCR in uterine epithelial cells after laser capture microdissection in situ or after epithelial cell coculture with macrophages or macrophage-secreted factors. When uterine macrophage recruitment was impaired by mating with seminal plasma-deficient males, epithelial cell Fut2 expression on Day 3.5 postcoitus (pc) was reduced compared to intact-mated controls. Epithelial cell Fut2 was upregulated in vitro by coculture with macrophages or macrophage-conditioned medium (MCM). Macrophage-derived cytokines LIF, IL1B, and IL12 replicated the effect of MCM on Fut2 mRNA expression, and MCM-stimulated expression was inhibited by anti-LIF and anti-IL1B neutralizing antibodies. The effects of acute macrophage depletion on fucosylated structures detected with lectins Ulex europaeus 1 (UEA-1) and Lotus tetragonolobus purpureas (LTP), or LewisX immunoreactivity, were quantified in vivo in Cd11b-dtr transgenic mice. Depletion of macrophages caused a 30% reduction in luminal epithelial UEA-1 staining and a 67% reduction in LewisX staining in uterine tissues of mice hormonally treated to mimic early pregnancy. Together, these data demonstrate that uterine epithelial Fut2 mRNA expression and terminal fucosylation of embryo attachment ligands is regulated in preparation for implantation by factors including LIF and IL1B secreted from macrophages recruited during the inflammatory response to insemination.

Matrix metalloproteinases and their tissue inhibitors in endometrial remodelling and menstruation

The architecture of the human endometrium is extensively remodelled during the course of each normal menstrual cycle, unlike most other tissues and organs which undergo very little change during adult life. During menstruation, when loss of most of the functionalis layer occurs, there is concomitant epithelial regrowth; repair of the luminal surface is complete almost as bleeding ceases. During the proliferative phase of the cycle and under the influence of rising oestrogen levels, the stromal cells, glands and blood vessels undergo rapid proliferation which results in tissue thickening. Following ovulation (around day 14 of the idealized 28-day cycle), the secretory phase of the cycle is characterized by increasing tortuosity of the spiral arterioles and glands and increased glandular secretory activity. After about day 22, decidualization of many of the stromal fibroblasts also occurs, the resultant decidual cells having many characteristics typical of epithelial cells. Periods of tissue oedema are apparent both in mid-proliferative (days 8–11) and mid-secretory (days 20–23) endometrium. Late in the cycle, there is regression of the tissue as menstruation is initiated.

Spermatozoa and seminal plasma induce a greater inflammatory response in the ovine uterus at oestrus than dioestrus

Leukocyte infiltration and increased synthesis of cytokines in response to insemination is considered to enhance reproductive success. The present study investigated the inflammatory response to whole semen, spermatozoa and seminal plasma, with and without the addition of antibiotics, in the ovine uterus at oestrus and dioestrus. Seminal plasma and spermatozoa both contributed to increased IL-8 secretion (P < 0.01) by endometrial epithelial cells and a concurrent infiltration by neutrophils (P < 0.01). Increased GM-CSF secretion (P < 0.01) occurred in response to whole semen and spermatozoa when antibiotics were not used. Macrophages and eosinophils increased (P < 0.05) in the endometrial stroma when antibiotics were not used, and fewer mast cells were detected in the deep endometrial stroma after treatments containing antibiotics (P < 0.05). Neutrophil and IL-8 responses to insemination were greater at oestrus (P < 0.01) than at dioestrus and the GM-CSF response followed a similar trend. Eosinophil numbers were increased at oestrus (P < 0.01) but minimally affected by insemination. More macrophages were located in the superficial endometrial stroma at oestrus. These results indicate that spermatozoa, seminal plasma and possibly bacteria contribute to the post-insemination inflammatory response, and that leukocytes, GM-CSF and IL-8 secretion in the ovine uterus are influenced by ovarian hormones.

Estrogen-mediated endothelial progenitor cell biology and kinetics for physiological postnatal vasculogenesis

Estrogen has been demonstrated to promote therapeutic reendothelialization after vascular injury by bone marrow (BM)-derived endothelial progenitor cell (EPC) mobilization and phenotypic modulation. We investigated the primary hypothesis that estrogen regulates physiological postnatal vasculogenesis by modulating bioactivity of BM-derived EPCs through the estrogen receptor (ER), in cyclic hormonally regulated endometrial neovascularization. Cultured human EPCs from peripheral blood mononuclear cells (PB-MNCs) disclosed consistent gene expression of ER alpha as well as downregulated gene expressions of ER beta. Under the physiological concentrations of estrogen (17beta-estradiol, E2), proliferation and migration were stimulated, whereas apoptosis was inhibited on day 7 cultured EPCs. These estrogen-induced activities were blocked by the receptor antagonist, ICI182,780 (ICI). In BM transplanted (BMT) mice with ovariectomy (OVX) from transgenic mice overexpressing beta-galactosidase (lacZ) regulated by an endothelial specific Tie-2 promoter (Tie-2/lacZ/BM), the uterus demonstrated a significant increase in BM-derived EPCs (lacZ expressing cells) incorporated into neovasculatures detected by CD31 immunohistochemistry after E2 administration. The BM-derived EPCs that were incorporated into the uterus dominantly expressed ER alpha, rather than ER beta in BMT mice from BM of transgenic mice overexpressing EGFP regulated by Tie-2 promoter with OVX (Tie-2/EGFP/BMT/OVX) by ERs fluorescence immunohistochemistry. An in vitro assay for colony forming activity as well as flow cytometry for CD133, CD34, KDR, and VE-cadherin, using human PB-MNCs at 5 stages of the female menstrual-cycle (early-proliferative, pre-ovulatory, post-ovulatory, mid-luteal, late-luteal), revealed cycle-specific regulation of EPC kinetics. These findings demonstrate that physiological postnatal vasculogenesis involves cyclic, E2-regulated bioactivity of BM-derived EPCs, predominantly through the ER alpha.

Neutrophil depletion retards endometrial repair in a mouse model

The contribution of the high abundance of inflammatory cells present in the human endometrium prior to and during menstruation is unknown with respect to endometrial repair and/or menstruation. In this study, the presence and localisation of markers for key inflammatory cells have been examined in a mouse model of endometrial breakdown and repair and the functional contribution of neutrophils has been determined. In the model, decidualisation is artificially induced and progesterone support withdrawn; the endometrial tissue progressively breaks down by 24 h after progesterone withdrawal and, by 48 h, has usually undergone complete repair. Neutrophils have been identified in low abundance in decidual tissue, rise in number during breakdown and are most abundant during early repair. Macrophages are barely detectable during breakdown or repair in this model, whereas uterine natural killer cells are found only in intact decidua. The functional contribution of neutrophils to endometrial breakdown and repair has been assessed via neutrophil depletion by using the antibody RB6-8C5. This antibody significantly depletes neutrophils from the circulation and tissue, affects endometrial breakdown and markedly delays endometrial repair. This study has therefore demonstrated that neutrophils are the most abundant leucocyte in this model and that they play an important functional role in the processes of endometrial breakdown and repair.

The presence of endometrial cells in the peritoneal cavity enhances monocyte recruitment and induces inflammatory cytokines in mice: implications for endometriosis

OBJECTIVE

To determine the inflammatory response in the peritoneal cavity by the presence of endometrial cells and the role of the mesothelium.

DESIGN

In vivo study using mice.

SETTING

University research laboratory.

ANIMAL(S)

Female Swiss Webster mice, 8 to 10 weeks old.

INTERVENTION(S)

Homogenous mouse endometrial epithelial and stromal cells were injected intraperitoneally. Peritoneal lavage and mesothelium were collected 4 to 72 hours after the administration.

MAIN OUTCOME MEASURE(S)

We determined the number of peritoneal macrophages, and the production and gene expression of monocyte chemotactic protein-1 (MCP-1/JE), interleukin 1alpha (IL-1alpha), and interleukin 6 (IL-6).

RESULT(S)

The intraperitoneal administration of endometrial cells increased the number of peritoneal macrophages, production of MCP-l, IL-1alpha, and IL-6, and expression of mesothelial MCP-1/JE, IL-1alpha, and IL-6 genes in recipient mice.

CONCLUSION(S)

These results suggest that retrograde menstruation could account for the increased presence of inflammatory mediators in the peritoneal cavity of women with endometriosis. The mesothelium could play an active role in endometriosis in addition to providing an attachment stratum for the endometrial cells.

Oestradiol regulation of antigen presentation by uterine stromal cells: role of transforming growth factor-beta production by epithelial cells in mediating antigen-presenting cell function

We have previously shown that oestradiol treatment of ovariectomized rats for 3 days inhibits antigen presentation by uterine stromal cells at a time when oestradiol increases the numbers of antigen-presenting cells (APC) in the uterine stroma. In the present study, we found that oestradiol treatment for 1 day is sufficient to inhibit antigen presentation by stromal cells. To define the mechanism(s) of this inhibition, we examined the effect of cytokines and found that exogenous transforming growth factor-beta (TGF-beta) inhibits antigen presentation when stromal cells from saline- but not oestradiol-treated animals are incubated with ovalbumin (OVA)-specific T cells and OVA. In contrast, antigen presentation by uterine epithelial cells was not affected by TGF-beta. In other studies, the acute inhibitory effect of oestradiol (1 day) on stromal antigen presentation is fully reversed when anti-TGF-beta antibody is added to the culture media. When given for 3 days, oestradiol inhibition of antigen presentation is partially reversed by anti-TGF-beta antibody at a time when antibodies to tumour necrosis factor-alpha and interleukin-10 have no effect. To determine whether uterine epithelial cells produce TGF-beta, epithelial cells were grown to confluence on transwell inserts. Our findings indicate that uterine epithelial cells produce biologically active TGF-beta which is preferentially released basolaterally in the direction of underlying stromal cells. When oestradiol is given to ovariectomized rats 1 day before sacrifice, TGF-beta production by epithelial cells increases within 24 hr in culture, relative to saline controls. Taken together, these results suggest that oestradiol inhibition of stromal cell antigen presentation is mediated through the stimulatory effect of oestradiol on TGF-beta production by epithelial cells.

Human immunodeficiency virus receptor and coreceptor expression on human uterine epithelial cells: regulation of expression during the menstrual cycle and implications for human immunodeficiency virus infection

Human immunodeficiency virus-1 (HIV-1) is primarily a sexually transmitted disease. Identification of cell populations within the female reproductive tract that are initially infected, and the events involved in transmission of infection to other cells, remain to be established. In this report, we evaluated expression of HIV receptors and coreceptors on epithelial cells in the uterus and found they express several receptors critical for HIV infection including CD4, CXCR4, CCR5 and galactosylceramide (GalC). Moreover, expression of these receptors varied during the menstrual cycle. Expression of CD4 and CCR5 on uterine epithelial cells is high throughout the proliferative phase of the menstrual cycle when blood levels of oestradiol are high. In contrast, CXCR4 expression increased gradually throughout the proliferative phase. During the secretory phase of the cycle when both oestradiol and progesterone are elevated, CD4 and CCR5 expression decreased whereas CXCR4 expression remained elevated. Expression of GalC on endometrial glands is higher during the secretory phase than during the proliferative phase of the menstrual cycle. Because epithelial cells line the female reproductive tract and express HIV receptors and coreceptors, it is likely that they are one of the first cell types to become infected. The hormonal regulation of HIV receptor expression may affect a woman's susceptibility to HIV infection during her menstrual cycle. Moreover, selective coreceptor expression could account for the preferential transmission of R5-HIV-1 strains to women. In addition, these studies provide evidence that the uterus, and potentially the entire upper reproductive tract, are important sites for the initial events involved in HIV infection.

Macrophages, oxidation, and endometriosis

Retrograde menstruation has been suggested to be the cause for the presence of endometrial cells in the peritoneal cavity. However, little is known about the events that lead to the adhesion and growth of these cells that ultimately result in endometriosis, considering the fact that the disease occurs only in certain women despite the common occurrence of retrograde menstruation in most women. We postulate that, in normal women, the endometrial cells and tissue that arrive in the peritoneal cavity during menstruation are effectively removed by macrophages that are chemoattracted and become resident tissue macrophages in the peritoneal cavity. In contrast, the peritoneal macrophages in women with endometriosis are nonadherent and ineffectively scavenged, resulting in the sustained presence and growth of the endometrial cells. We also postulate that the peritoneal fluid is not a passive reservoir of the factors secreted by cells of the peritoneum, but actively promotes endometriosis. The peritoneal fluid is rich in lipoproteins, particularly low-density lipoprotein, which generates oxidized lipid components in a macrophage-rich inflammatory milieu. The oxidants exacerbate the growth of endometriosis by inducing chemoattractants such as MCP-1 and endometrial cell growth-promoting activity. We provide evidence for the presence of oxidative milieu in the peritoneal cavity of women with endometriosis, the nonscavenging properties of macrophages that are nonadherent, and the synergistic interaction between macrophages, oxidative stress, and the endometrial cells. For example, the peritoneal fluid lipoproteins of subjects with endometriosis have increased the propensity to undergo oxidation as compared with plasma lipoproteins, and the subjects also have increased titer of autoantibodies to oxidatively modified proteins. If the oxidative proinflammatory nature of the peritoneal fluid is an important mediator of endometriosis growth, anti-inflammatory agents and antioxidants might afford protection against endometriosis.

Identification and implantation stage-specific expression of an interferon-alpha-regulated gene in human and rat endometrium

Implantation of the developing blastocyst is regulated by multiple effectors, such as steroid hormones, growth factors, and cytokines. To understand how these diverse signaling pathways interact to modulate uterine gene expression, we employed a gene expression screen technique to identify the molecules that are induced in the periimplantation rat uterus. Here we report the isolation of a complementary DNA representing a novel gene, interferon-regulated gene 1 (IRG1). This gene exhibits significant homology to interferon (IFN)-alpha/beta-inducible human genes p27 and 6-16, indicating that these genes may belong to the same family. Consistent with this finding, expression of IRG1 messenger RNA (mRNA) in rat uterus increased about 20-fold in response to IFNalpha. Uterine expression of IRG1 was also stimulated by estrogen and was partially inhibited by an antiestrogen, ICI 182,780. In pregnant rats, IRG1 expression was high on day 1, but declined on days 2 and 3. The level of IRG1 mRNA again rose transiently on day 4 immediately preceding implantation. In situ hybridization analysis localized the IRG1 mRNA expression in the endometrial epithelium and the surrounding stroma. Interestingly, the expression of p27, which shows high homology to IRG1, was strongly enhanced in human endometrium during the midsecretory phase of the menstrual cycle, overlapping the putative window of implantation. Both IRG1 and p27 mRNAs are therefore induced in the endometrium in an implantation stage-specific manner. We also observed a synergistic interaction between IFNalpha and estrogen receptor signaling pathways that led to maximal induction of p27 mRNA in Ishikawa cells. Although the functional roles of IRG1 and p27 remain unclear, we describe for the first time, identification of a gene family regulated by IFNalpha in both rodent and human uteri. More importantly, our studies reveal that a complex interplay between the steroid hormone and IFN pathways regulates the expression of these genes in the endometrium at the time of implantation.

Messenger ribonucleic acid encoding interferon-inducible guanylate binding protein 1 is induced in human endometrium within the putative window of implantation

The putative window of embryo implantation in the human opens between days 19--24 of the menstrual cycle. During this period, the endometrium undergoes distinctive structural and functional changes orchestrated by steroid hormones, growth factors, and cytokines to attain a receptive phase in which it acquires the ability to implant the developing embryo. A major challenge in the study of human reproduction is to identify the molecular signals that participate in the establishment of this critical receptive phase in the context of the natural cycle. Toward this goal, we analyzed human endometrial biopsies at various days of the menstrual cycle by employing messenger RNA (mRNA) differential display technique. We isolated several complementary DNAs representing genes that are either up- or down-regulated within the putative window of implantation. We identified one of these genes as that encoding interferon (IFN)-inducible guanylate-binding protein 1 (or GBP1), which possesses GTPase activity. Analysis of endometrial biopsies by Northern blotting and RT-PCR demonstrated that GBP1 mRNA is specifically induced at the midsecretory phase of the menstrual cycle. In situ hybridization analysis revealed that GBP1 mRNA expression is localized in the glandular epithelial cells as well as in the stroma in the immediate vicinity of the glands. We observed that treatment of human endometrial adenocarcinoma cell, Ishikawa, with IFN-gamma or IFN-alpha markedly induced the expression of GBP1 mRNA. IFN-gamma was, however, a more potent inducer of GBP1 than IFN-alpha. Consistent with this finding, the temporal profile of GBP1 expression during the menstrual cycle resembled that of IFN-gamma mRNA more closely than that of IFN-alpha, predicting a regulatory role of IFN-gamma in GBP1 expression in midsecretory human endometrium. Although the precise function of GBP1 in the receptive human uterus remains unclear, its unique expression overlapping the putative window of implantation suggests that it might serve as a useful marker of uterine receptivity in the human.

Expression of the chemokine eotaxin and its receptor, CCR3, in human endometrium

Eosinophils are present in human endometrium only immediately before and during menstruation, suggesting a role in that process. The expression of the eosinophil chemoattractant, eotaxin, and its receptor, CCR3, within the human endometrium were investigated by immunohistochemical analysis of tissue sections spanning the entire menstrual cycle. Eotaxin was localized to perivascular cells in the late secretory phase, and it was also identified in eosinophils. However, the highest levels of this chemokine were present in both luminal and glandular epithelial cells during the proliferative and secretory phases of the cycle. Treatment of endometrial tissue with monensin, which blocks protein secretion, increased epithelial immunoreactive eotaxin, substantiating synthesis in these cells. Although the CCR3 receptor was expressed by eosinophils, it was also strongly expressed by endometrial epithelial cells. The CCR3 receptor on purified, cultured endometrial epithelial cells was functional, as assessed by a transient Ca(2+) flux in response to eotaxin. These analyses demonstrate that eotaxin is expressed by endometrial cells and may therefore be involved in the recruitment of eosinophils into this tissue premenstrually. However, the observation that this chemokine and the CCR3 molecule are strongly expressed by epithelial cells throughout the cycle suggests that these proteins may have additional important functions within the endometrium.

Menstruation: induction by matrix metalloproteinases and inflammatory cells

Menstruation occurs at the end of a normal reproductive cycle in the human female, following the fall in progesterone resulting from the demise of the corpus luteum. Current data support a central role for the matrix metalloproteinases in menstruation but their focal pattern of expression within peri-menstrual and menstrual endometrium suggests local rather than hormonal regulation. This review emphasizes the similarities between menstruation and an inflammatory process and examines the relationship between cells of hemopoietic lineage, particularly mast cells, eosinophils, neutrophils and macrophages, and the local production and activation of matrix metalloproteinases within the endometrium. It proposes a complex of critical regulatory circuits, initially activated by the withdrawal of progesterone, which provide interactions between the migratory cells that produce a myriad of important regulatory molecules and endometrial stromal and epithelial cells which produce both chemokines and matrix metalloproteinases. These mechanisms could account for the focal nature of the tissue degradation at menstruation.

Optimisation of a technique for isolating lymphocyte subsets from human endometrium

Human endometrium is a rich source of lymphocytes which may have unique immunoregulatory functions. The aim of this study was to compare current procedures for endometrial tissue disaggregation, and optimise a method for isolation of endometrial lymphocytes. Tissue was obtained from 41 women undergoing elective hysterectomy or dilation and curettage (D&C) for reasons of benign non-endometrial pathology. Specimens were exposed to reduction/chelation, mechanical or enzymatic disruption. Optimal single cell suspensions of high yields (mean 8.8 x 10(6) range 3.5-18 x 10(6)lymphs) and good viability (60%) were obtained, using a combination of collagenase IV (200 U/ml) and DNase I (35 U/ml). Suspensions were further purified by density gradient centrifugation. Multi-colour flow cytometry was used for analysis of endometrial lymphocyte subsets. Cell suspensions were stained with mAbs specific for CD3, CD4, CD8, CD56, CD45 and CD14, and it was clearly shown that the developed method had no effect on surface glycoprotein expression. Phenotypic analysis revealed consistent populations of endometrial large granular lymphocytes (CD56+CD3-) 54.16%, and T-cells (CD3+) 37.73%. This technique was applicable to the characterisation of T-cell populations, including CD8+ (56.6%), CD4+ (44.0%), and particularly smaller populations of CD4+CD8+(3.56%), CD4-CD8-(3.34%) and CD56+(6.3%) due to it's sensitivity. In conclusion, optimised enzymatic digestion, in combination with flow cytometry provides an effective method for phenotypic examination of small endometrial lymphocyte subpopulations.

Antigen-presenting cells in the human female reproductive tract: analysis of antigen presentation in pre- and post-menopausal women

PROBLEM

To determine whether cells in the female reproductive tract (FRT) are functionally capable of presenting antigen to T cells.

METHOD OF STUDY

Analysis was done by determining the proliferation of purified autologous T cells to antigen, following co-incubation with non-proliferating cell suspensions isolated from the uterus and prepared by enzymatic digestion of reproductive tract tissues from hysterectomy patients with benign disease.

RESULTS

All uterine preparations analyzed were functionally capable of presenting antigen; the ability to present antigen was independent of pre- and post-menopausal status. In contrast, some, but not all, tissues from the ovary, Fallopian tube, cervix, and vagina were capable of presenting antigen.

CONCLUSION

These results suggest that the human FRT is an inductive site for immune responses. Regulation of antigen presentation in the reproductive tract may be important for protection against sexually transmitted diseases.

Analysis of telomerase expression and proliferative activity in the different layers of cyclic endometrium

To gain better insights into cell kinetics under physiological conditions, telomerase activity in the functional and basal layers of cyclic endometrium (n = 33) was compared with the immunostaining of glandular and stromal cells within these layers (n = 25). Two immunohistochemical proliferation markers were used to demarcate cells in the G1 phase of the cell cycle. In contrast to previous expectations, telomerase activity and both glandular and stromal proliferative activities were all significantly higher in the functional than in the basal endometrium (P < 0.002). The course of telomerase activity in the endometrial layers during the ovarian cycle was significantly associated with the proliferative scores for the functional and basal endometrial glands and the functional stroma but not the stromal compartment of the basal layer. Our findings indicate that the telomerase activity in cyclic endometrium is associated with the total number of proliferating glandular and stromal cells in the functional layer. Proliferating daughter cells of telomerase-competent stem cells may account for the lower levels of telomerase detected in normal basal endometrium.

Current concepts of the mechanisms of menstruation: a normal process of tissue destruction

Current data support the contention that menstruation is the consequence of the actions of matrix metalloproteinases (MMPs) in the endometrium, and that these enzymes are stimulated by the products of an inflammatory process. A number of MMPs, capable of degrading both interstitial matrix and basement membrane components, have been localized to perimenstrual endometrium, and the focal nature of their production suggests local regulation. Emphasis is placed on important relationships between cells of the immune system (specifically, mast cells, eosinophils, neutrophils and macrophages), and the local production and activation of MMPs, whose degradative actions lead to loss of integrity of blood vessels, destruction of endometrial interstitial matrix and the resultant bleeding characteristic of menstruation.

IFN-γ Is Produced by Polymorphonuclear Neutrophils in Human Uterine Endometrium and by Cultured Peripheral Blood Polymorphonuclear Neutrophils

Cytokines present in the human uterus play an important role both in modulating immune responses to infectious challenge and in the establishment and maintenance of pregnancy. In particular, successful implantation and pregnancy is thought to require the establishment of a Th2 environment, while Th1 cytokines are associated with pregnancy loss and infertility. On the other hand, a Th1 response appears to be required for the resolution of acute infection. Using novel confocal microscopic analysis of fresh sections of human tissue, we have investigated the production of IFN-γ, a Th1 cytokine, in human endometria. Extracellular IFN-γ, mostly associated with matrix components, was located immediately beneath the luminal epithelium and along the glandular epithelium proximal to the lumen. As evidenced by intracellular staining, IFN-γ is produced by both stromal cells and intraepithelial lymphocytes through all stages of the menstrual cycle. Surprisingly, the stromal cell containing intracellular IFN-γ was identified as a polymorphonuclear neutrophil on the basis of its reactivity with a panel of mAbs and its nuclear morphology. We further found that polymorphonuclear neutrophils isolated from normal donors produce IFN-γ in response to stimulation with LPS, IL-12, and TNF-α. Taken together, these findings suggest that polymorphonuclear neutrophils are capable of producing IFN-γ both in vitro and in vivo, indicating that their role in shaping immune responses may be more extensive than previously thought. Furthermore, these studies strongly suggest that polymorphonuclear neutrophils play an important role in determining immune responsiveness within the female reproductive tract.

Flow cytometric analysis of leukocytes in the human female reproductive tract: comparison of fallopian tube, uterus, cervix, and vagina

PROBLEM

The tissues of the human female reproductive tract (Fallopian tube, uterus, cervix, and vagina) may play different roles in the provision of mucosal immunity. The purpose of this study was to develop a uniform method suitable for quantitative comparison of the leukocytes from all these tissues.

METHOD OF STUDY

Tissues, typically 0.5-1.0 g, were dispersed by enzyme treatment. A flow cytometric gating procedure based on CD45-positivity and low far-red autofluorescence permitted unfractionated, freshly dispersed cells to be phenotyped with respect to T lymphocytes, B lymphocytes, macrophages, and granulocytes.

RESULTS

Reproductive tract tissues contain leukocytes that represent approximately 6-20% of the total number of cells, with the Fallopian tubes and uterus containing a higher proportion of leukocytes than the cervix and vagina. The uterine endometrium from post-menopausal women has fewer leukocytes than does uterine endometrium from pre-menopausal women. T lymphocytes are a major constituent (30-60%) of leukocytes from all tissues. The Fallopian tube contains granulocytes as another major constituent; granulocytes are significantly less numerous in the other tissues. All tissues contain B lymphocytes and macrophages as clearly detectable but minor components.

CONCLUSIONS

Three-color flow cytometry is an appropriate method for quantitative comparison of leukocytes from the different tissues of the female reproductive tract, during all phases of the menstrual cycle and within post-menopausal samples. Results indicate that the tissues differ from each other, particularly with respect to the large number of granulocytes in the Fallopian tubes.