Suppression of matrix metalloproteinase-9 by prostaglandin E(2) in peritoneal macrophage is associated with severity of endometriosis

Prostaglandin E2 in the Tumor Microenvironment, a Convoluted Affair Mediated by EP Receptors 2 and 4

The involvement of the prostaglandin E2 (PGE2) system in cancer progression has long been recognized. PGE2 functions as an autocrine and paracrine signaling molecule with pleiotropic effects in the human body. High levels of intratumoral PGE2 and overexpression of the key metabolic enzymes of PGE2 have been observed and suggested to contribute to tumor progression. This has been claimed for different types of solid tumors, including, but not limited to, lung, breast, and colon cancer. PGE2 has direct effects on tumor cells and angiogenesis that are known to promote tumor development. However, one of the main mechanisms behind PGE2 driving cancerogenesis is currently thought to be anchored in suppressed antitumor immunity, thus providing possible therapeutic targets to be used in cancer immunotherapies. EP2 and EP4, two receptors for PGE2, are emerging as being the most relevant for this purpose. This review aims to summarize the known roles of PGE2 in the immune system and its functions within the tumor microenvironment. SIGNIFICANCE STATEMENT: Prostaglandin E2 (PGE2) has long been known to be a signaling molecule in cancer. Its presence in tumors has been repeatedly associated with disease progression. Elucidation of its effects on immunological components of the tumor microenvironment has highlighted the potential of PGE2 receptor antagonists in cancer treatment, particularly in combination with immune checkpoint inhibitor therapeutics. Adjuvant treatment could increase the response rates and the efficacy of immune-based therapies.

Progesterone resistance in endometriosis: A pathophysiological perspective and potential treatment alternatives

Background

Endometriosis is a common gynecological disease affecting women of reproductive age. Patients with endometriosis frequently experience severe chronic pain and have higher chances to experience infertility. Progesterone resistance is a major problem that develops during the medical treatment of endometriosis, which often leads to treatment failure of hormonal therapies. Previous studies indicated that the dysregulation of progesterone receptors (PR) is the primary factor leading to progesterone resistance in endometriosis.

Methods

This review article systematically reviewed and summarized findings extracted from previously published papers available on PubMed, encompassing both experimental studies and clinical trials.

Main findings

Various determinants influencing PR expression in endometriosis have been identified, including the environmental toxins, microRNAs, cell signaling pathways, genetic mutations, and the pro-inflammatory cytokines. The selective estrogen/progesterone receptor modulators have emerged as novel therapeutic approaches for treating endometriosis, offering potential improvements in overcoming progesterone resistance.

Conclusion

Concerns and limitations persist despite the newly developed drugs. Therefore, studies on unraveling new therapeutic targets based on the molecular mechanisms of progesterone resistance is warranted for the development potential alternatives to overcome hormonal treatment failure in endometriosis.

Peritoneal immune microenvironment of endometriosis: Role and therapeutic perspectives

Endometriosis, an estrogen-dependent chronic inflammatory disease characterized by the growth of endometrium-like tissues outside the uterine cavity, affects 10% of reproductive-age women. Although the pathogenesis of endometriosis is uncertain, it is widely accepted that retrograde menstruation results in ectopic endometrial tissue implantation. Given that not all women with retrograde menstruation develop endometriosis, immune factors have been hypothesized to affect the pathogenesis of endometriosis. In this review, we demonstrate that the peritoneal immune microenvironment, including innate immunity and adaptive immunity, plays a central role in the pathogenesis of endometriosis. Current evidence supports the fact that immune cells, such as macrophages, natural killer (NK) cells, dendritic cells (DCs), neutrophils, T cells, and B cells, as well as cytokines and inflammatory mediators, contribute to the vascularization and fibrogenesis of endometriotic lesions, accelerating the implantation and development of ectopic endometrial lesions. Endocrine system dysfunction influences the immune microenvironment through overexpressed estrogen and progesterone resistance. In light of the limitations of hormonal therapy, we describe the prospects for potential diagnostic biomarkers and nonhormonal therapy based on the regulation of the immune microenvironment. Further studies are warranted to explore the available diagnostic biomarkers and immunological therapeutic strategies for endometriosis.

Promotion of BST2 expression by the transcription factor IRF6 affects the progression of endometriosis

Background

Endometriosis (EM) is a benign, multifactorial, immune-mediated inflammatory disease that is characterized by persistent activation of the NF-κB signaling pathway and some features of malignancies, such as proliferation and lymphangiogenesis. To date, the pathogenesis of EM is still unclear. In this study, we investigated whether BST2 plays a role in the development of EM.

Methods

Bioinformatic analysis was performed with data from public databases to identify potential candidate targets for drug treatment. Experiments were conducted at the cell, tissue, and mouse EM model levels to characterize the aberrant expression patterns, molecular mechanisms, biological behaviors of endometriosis as well as treatment outcomes.

Results

BST2 was significantly upregulated in ectopic endometrial tissues and cells compared with control samples. Functional studies indicated that BST2 promoted proliferation, migration, and lymphangiogenesis and inhibited apoptosis in vitro and in vivo. The transcription factor (TF) IRF6 induced high BST2 expression by directly binding the BST2 promoter. The underlying mechanism by which BST2 functions in EM was closely related to the canonical NF-κB signaling pathway. New lymphatic vessels may serve as a channel for the infiltration of immune cells into the endometriotic microenvironment; these immune cells further produce the proinflammatory cytokine IL-1β, which in turn further activates the NF-κB pathway to promote lymphangiogenesis in endometriosis.

Conclusion

Taken together, our findings provide novel insight into the mechanism by which BST2 participates in a feedback loop with the NF-κB signaling pathway and reveal a novel biomarker and potential therapeutic target for endometriosis.

Uterine Anteroposterior Diameter Measured by Transvaginal Sonography is a Predictor for Dysmenorrhea in Patients With and Without Endometriosis: A Pilot Study

PURPOSE

The aim of this study was to determine the correlation between uterine diameters and menstrual abdominal pain intensity in patients with and without endometriosis (EM), and the independent influence of EM on the pain intensity.

METHODS

Uterine diameters and the diagnosis of adenomyosis were ascertained by transvaginal ultrasonography (TVS). Menstrual abdominal pain intensity was estimated by visual analog scale (VAS). Linear regression was used to figure out the impact of uterine diameters and EM on the VAS scores. Logistic regression was used to calculate the correlation between uterine diameters and the diagnosis of adenomyosis. The cutoff values of uterine anteroposterior diameter (AD) to predict dysmenorrhea (VAS ≥ 4) and the diagnosis of adenomyosis were determined by receiver operating characteristic curves.

RESULTS

There were 220 patients with and 233 patients without EM included. Uterine AD independently correlated with the VAS scores in patients with (B = .230, P = .000) and without (B = .203, P = .000) EM. A uterine AD of 39.5 mm predicted dysmenorrhea in both groups. The presence of EM increased the VAS scores by 1.151 points when controlling for uterine diameters. Uterine AD also independently correlated with the diagnosis of adenomyosis under TVS in patients with (OR = 1.212, 95% CI = 1.130-1.301; P = .000) and without (OR = 1.192, 95% CI = 1.123-1.263; P = .000) EM. A uterine AD of 38.5 and 39.5 mm predicted the diagnosis of adenomyosis under TVS in patients with and without EM, respectively.

CONCLUSIONS

Increased uterine AD, which is probably ascribed to adenomyosis, plays an important role in augmented menstrual abdominal pain intensity. Meanwhile, the presence of EM reinforces the pain.

α-Mangostin Treats Early-Stage Adjuvant-Induced Arthritis of Rat by Regulating the CAP-SIRT1 Pathway in Macrophages

Background

Studies have found that α-mangostin (MG) can relieve experimental arthritis by activating cholinergic anti-inflammatory pathway (CAP). It affects the polarization of macrophages and the balance of related immune cell subpopulations, but the specific mechanism is still unclear. It has been found that silent information regulator 1 (SIRT1) is closely related to macrophage activity. The purpose of this study is to explore the mechanism of MG intervening in macrophage polarization during treatment of early adjuvant-induced (AIA) rats through the CAP-SIRT1 pathway.

Methods

We investigated the polarization of M1 macrophages and the differentiation of Th1 in AIA rats by flow cytometry. Activity of acetylcholinesterase (AChE) and the level of nicotinic adenine dinucleotide (NAD+) in serum were also detected, and immunohistochemical was used to detect the levels of α7 nicotinic cholinergic receptor (α7nAChR) and SIRT1. Then in macrophages, the molecular mechanism of MG regulating the abnormal activation of macrophages in rats with early AIA through the CAP-SIRT1 pathway was studied.

Results

MG can significantly inhibit the polarization of M1 macrophages and the differentiation of Th1 in AIA rats in the acute phase of inflammation. MG can significantly inhibit the activity of AChE and increase the level of NAD+, thereby further up-regulated the expression levels of α7nAChR and SIRT1. Meanwhile, MG inhibited nuclear factor-κB (NF-κB)-mediated inflammation by activating the CAP-SIRT1 pathway in macrophages.

Conclusion

In summary, the stimulation of MG induced CAP activation, which up-regulated SIRT1 signal, and thereby inhibited M1 polarization through the NF-κB pathway, and improved the pathological immune environment of early-stage AIA rats.

Metformin as a Potential Treatment Option for Endometriosis

Endometriosis is a common disease in women of reproductive age, and its pathogenesis seems to be largely affected by hormone imbalance, inflammation, oxidative stress, and autophagy dysregulation. These pathophysiological disturbances interact with one another through mechanisms that are still awaiting elucidation. The aim of this article is to present current knowledge regarding the possibilities of using metformin in the pharmacological treatment of endometriosis. Metformin is an insulin sensitizer widely used for the treatment of type 2 diabetes mellitus. The pleiotropic effects of metformin are mainly exerted through the activation of AMP-activated protein kinase, which is the key cellular energy homeostasis regulator that inhibits mTOR, a major autophagy suppressor. Metformin regresses endometriotic implants by increasing the activity of superoxide dismutase. It is also an inhibitor of metalloproteinase-2, decreasing the levels of the vascular endothelial growth factor and matrix metalloproteinase-9 in animal studies. In endometriosis, metformin might modify the stroma-epithelium communication via Wnt2/β-catenin. With its unique therapeutic mechanisms and no serious side effects, metformin seems to be a helpful anti-inflammatory and anti-proliferative agent in the treatment of endometriosis. It could be a missing link for the successful treatment of this chronic disease.

Metabolic Enzyme Triosephosphate Isomerase 1 and Nicotinamide Phosphoribosyltransferase, Two Independent Inflammatory Indicators in Rheumatoid Arthritis: Evidences From Collagen-Induced Arthritis and Clinical Samples

Metabolic intervention is a novel anti-rheumatic approach. The glycolytic regulator NAMPT has been identified as a therapeutic target of rheumatoid arthritis (RA), while other metabolic regulators coordinating NAMPT to perpetuate inflammation are yet to be investigated. We continuously monitored and validated expression changes of Nampt and inflammatory indicators in peripheral while blood cells from rats with collagen-induced arthritis (CIA). Gene transcriptional profiles of Nampt+ and Nampt++ samples from identical CIA rats were compared by RNA-sequencing. Observed gene expression changes were validated in another batch of CIA rats, and typical metabolic regulators with persistent changes during inflammatory courses were further investigated in human subjects. According to expression differences of identified genes, RA patients were assigned into different subsets. Clinical manifestation and cytokine profiles among them were compared afterwards. Nampt overexpression typically occurred in CIA rats during early stages, when iNos and Il-1β started to be up-regulated. Among differentially expressed genes between Nampt+ and Nampt++ CIA rat samples, changes of Tpi1, the only glycolytic enzyme identified were sustained in the aftermath of acute inflammation. Similar to NAMPT, TPI1 expression in RA patients was higher than general population, which was synchronized with increase in RFn as well as inflammatory monocytes-related cytokines like Eotaxin. Meanwhile, RANTES levels were relatively low when NAMPT and TPI1 were overexpressed. Reciprocal interactions between TPI1 and HIF-1α were observed. HIF-1α promoted TPI1 expression, while TPI1 co-localized with HIF-1α in nucleus of inflammatory monocytes. In short, although NAMPT and TPI1 dominate different stages of CIA, they similarly provoke monocyte-mediated inflammation.

The Role of Matrix Metalloproteinases in Endometriosis: A Potential Target

Endometriosis is a condition that is influenced by hormones and involves stroma and glands being found outside the uterus; there are increases in proliferation, invasion, internal bleeding, and fibrosis. Matrix metalloproteinases (MMPs) have been suggested to be crucial in the progression of invasion. The MMP family includes calcium-dependent zinc-containing endopeptidases, some of which not only affect the process of cell invasion but also participate in other physiological and pathological processes, such as angiogenesis and fibrosis. MMPs act as downstream-targeted molecules and their expression can be regulated by numerous factors such as estrogen, oxidative stress, cytokines, and environmental contaminants. Given their unique roles in endometriosis, MMPs may become effective biomarkers of endometriosis in the future. In the present review, we summarize the current literature on MMPs regarding their classification, function, and potential value for endometriosis, which may contribute to our knowledge of MMPs and MMP-targeted interventions.

The Role of Peritoneal Macrophages in Endometriosis

Endometriosis is an estrogen-dependent gynecological disorder, defined as the growth of endometrial stromal cells and glands at extrauterine sites. Endometriotic lesions are more frequently located into the abdominal cavity, although they can also be implanted in distant places. Among its etiological factors, the presence of immune dysregulation occupies a prominent place, pointing out the beneficial and harmful outcomes of macrophages in the pathogenesis of this disease. Macrophages are tissue-resident cells that connect innate and adaptive immunity, playing a key role in maintaining local homeostasis in healthy conditions and being critical in the development and sustainment of many inflammatory diseases. Macrophages accumulate in the peritoneal cavity of women with endometriosis, but their ability to clear migrated endometrial fragments seems to be inefficient. Hence, the characteristics of the peritoneal immune system in endometriosis must be further studied to facilitate the search for new diagnostic and therapeutic tools. In this review, we summarize recent relevant advances obtained in both mouse, as the main animal model used to study endometriosis, and human, focusing on peritoneal macrophages obtained from endometriotic patients and healthy donors, under the perspective of its future clinical translation to the role that these cells play on this pathology.

Peritoneal Fluid from Patients with Ovarian Endometriosis Displays Immunosuppressive Potential and Stimulates Th2 Response

Endometriosis is a common gynaecological disorder characterized by the ectopic growth of endometrial tissue outside the uterine cavity. It is associated with chronic pelvic inflammation and autoimmune reactivity manifesting by autoantibody production and abrogated cellular immune responses. Endometriotic peritoneal fluid contains various infiltrating leucocyte populations and a bulk of proinflammatory and immunoregulatory cytokines. However, the nature and significance of the peritoneal milieu in women with endometriosis still remains obscure. Therefore, the aim of the present study was to investigate the immunoregulatory activity of the peritoneal fluid (PF) from women with endometriosis. The peritoneal fluid samples were collected during laparoscopic surgery from 30 women with and without endometriosis. Immunoregulatory cytokines (IL-2, IL-4, IL-6, IL-10, IL-17A, IFN-γ and TNF) and chemokines (CCL2, CCL5, CXCL8 and CXCL9) were evaluated in PF and culture supernatants generated by unstimulated and CD3/CD28/IL-2-stimulated CD4⁺ T cells cultured in the presence of PF. The effect of PF on the generation of Treg and Th17 cells in CD4⁺ T cell cultures, as well as the natural cytotoxic activity of peripheral blood mononuclear cells, was also investigated. Concentrations of IL-6, IL-10, CCL2, CXCL8 and CXCL9 were significantly upregulated in the PF from women with endometriosis when compared to control women, whereas concentrations of other cytokines and chemokines were unaffected. The culturing of unstimulated and CD3/CD28/IL-2-stimulated CD4⁺ T cells in the presence of endometriotic PF resulted in the downregulation of their IL-2, IFN-γ, IL-17A and TNF production as compared to culture medium alone. On the other side, endometriotic PF significantly stimulated the production of IL-4 and IL-10. Endometriotic PF also stimulated the release of CCL2 and CXCL8, whereas the production of CCL5 and CXCL9 was downregulated. Endometriotic PF stimulated the generation of Treg cells and had an inhibitory effect on the generation of Th17 cells in cultures of CD4⁺ T cells. It also inhibited the NK cell cytotoxic activity of the peripheral blood lymphocytes. These results strongly imply that the PF from patients with endometriosis has immunoregulatory/immunosuppressive activity and shifts the Th1/Th2 cytokine balance toward the Th2 response, which may account for deviation of local and systemic immune responses. However, a similar trend, albeit not a statistically significant one, was also observed in case of PF from women without endometriosis, thus suggesting that peritoneal milieu may in general display some immunoregulatory/immunosuppressive properties. It should be stressed, however, that our present observations were made on a relatively small number of PF samples and further studies are needed to reveal possible mechanism(s) responsible for this phenomenon.

PPARγ Agonists: Emergent Therapy in Endometriosis

Endometriosis is one of the major gynecological diseases of reproductive-age women. This disease is characterized by the presence of glands and stroma outside the uterine cavity. Several studies have shown the major role of inflammation, angiogenesis, adhesion and invasion, and apoptosis in endometriotic lesions. Nevertheless, the mechanisms underlying endometriotic mechanisms still remain unclear and therapies are not currently efficient. The introduction of new agents can be effective by improving the condition of patients. PPARγ ligands can directly modulate these pathways in endometriosis. However, data in humans remain low. Thus, the purpose of this review is to summarize the potential actions of PPARγ agonists in endometriosis by acting on inflammation, angiogenesis, invasion, adhesion, and apoptosis.

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.

Protopanaxadiol improves endometriosis associated infertility and miscarriage in sex hormones receptors-dependent and independent manners

Background: Patients with endometriosis (EMs) have high risks of infertility and spontaneous abortion. How to remodel the fertility of patients with EMs has always been the hot spot and difficulty in the field of reproductive medicine. As an aglycone of ginsenosides, protopanaxadiol (PPD) possesses pleiotropic biological functions and has high medicinal values. We aimed to investigate the effect and potential mechanism of PPD in the treatment of EMs-associated infertility and spontaneous abortion.

Methods: The EMs mice models were constructed by allotransplantation. The pregnancy rates, embryo implantation numbers and embryo resorption rates of control and EMs were counted. RNA sequencing, qRT-PCR, enzyme linked immunosorbent assay (ELISA) and FCM analysis were performed to screen and confirm the expression of endometrial receptivity/decidualization-related molecules, inflammation cytokines and NK cell function-related molecules in vitro and/or in vivo. The SWISS Target Prediction, STRING and Cytoscape were carried out to predict the potential cellular sensory proteins, the protein-protein interaction (PPI) network between sensory proteins and fertility-related molecules, respectively. Micro-CT detection, liver and kidney function tests were used to evaluate the safety.

Results: Here, we observe that PPD significantly up-regulates endometrial receptivity-related molecules (e.g., Lif, Igfbp1, Mmps, collagens) and restricts pelvic inflammatory response (low levels of IL-12 and IFN-γ) of macrophage, and further remodel and improve the fertility of EMs mice. Additionally, PPD increases the expression of decidualization-related genes and Collagens, and promotes the proliferation, residence, immune tolerance and anagogic functions of decidual NK cells (low levels of CD16 and NKp30, high levels of Ki67, VEGF, TGF-β) in pregnant EMs mice, and further triggers decidualization, decidual NK cell-mediated maternal-fetal immune tolerance and angiogenesis, preventing pregnant EMs mice from miscarriage. Mechanically, these effects should be dependent on ESRs, PGR and other sensory proteins (e.g., AR). Compared with GnRHa (the clinic first-line drug for EMs), PPD does not lead to the decline of serum estrogen and bone loss.

Conclusion: These data suggest that PPD prevents EMs-associated infertility and miscarriage in sex hormones receptors-dependent and independent manners possibly, and provides a potential therapeutic strategy with high efficiency and low side effects to remodels the fertility of patients with EMs.

Nanomedicines for Endometriosis: Lessons Learned from Cancer Research

Endometriosis is an incurable gynecological disease characterized by the abnormal growth of endometrium-like tissue, characteristic of the uterine lining, outside of the uterine cavity. Millions of people with endometriosis suffer from pelvic pain and infertility. This review aims to discuss whether nanomedicines that are promising therapeutic approaches for various diseases have the potential to create a paradigm shift in endometriosis management. For the first time, the available reports and achievements in the field of endometriosis nanomedicine are critically evaluated, and a summary of how nanoparticle-based systems can improve endometriosis treatment and diagnosis is provided. Parallels between cancer and endometriosis are also drawn to understand whether some fundamental principles of the well-established cancer nanomedicine field can be adopted for the development of novel nanoparticle-based strategies for endometriosis. This review provides the state of the art of endometriosis nanomedicine and perspective for researchers aiming to realize and exploit the full potential of nanoparticles for treatment and imaging of the disorder.

Use of selective PGE2 receptor antagonists on human endometriotic stromal cells and peritoneal macrophages

Non-hormonal therapeutic strategies for endometriosis are needed. The aim of this study was to characterize the effects of prostaglandin (PG)E2 receptor inhibitors to explore their potential as novel therapeutic strategies for endometriosis. The expression of PGE2 receptors (EP2 and EP4) in donated tissues from human ovarian endometriosis, adenomyosis and peritoneal endometriosis was examined using immunohistochemistry. Human endometriotic stromal cells (ESC) isolated from ovarian endometriotic tissue and peritoneal macrophages were treated with EP2 and EP4 antagonists. cAMP accumulation and the effect of EP antagonists were measured using cAMP assays. DNA synthesis in ESC was detected using bromodeoxyuridine incorporation analysis. Interleukin (IL)-6 and IL-8 protein levels in ESC supernatants were measured using ELISAs. mRNA expression level for aromatase by ESC, and selected cytokines by peritoneal macrophages was measured using RT-PCR. EP2 and EP4 receptors were expressed in cells derived from control and diseased tissue, ovarian endometriotic, adenomyotic and peritoneal lesions. A selective EP2 antagonist reduced DNA synthesis, cAMP accumulation and IL-1β-induced proinflammatory cytokine secretion and aromatase expression. A selective EP4 antagonist negated IL-1β-induced IL-6 secretion and aromatase expression. In peritoneal macrophages, EP expression was elevated in endometriosis samples but the EP4 antagonist reduced cAMP levels and expression of vascular endothelial growth factor, chemokine ligand 2 and chemokine ligand 3 mRNA. EP2 and EP4 are functioning in endometriosis lesions and peritoneal macrophages, and their selective antagonists can reduce EP-mediated actions, therefore, the EP antagonists are potential therapeutic agents for controlling endometriosis.

Extracellular vesicle-associated VEGF-C promotes lymphangiogenesis and immune cells infiltration in endometriosis

Endometriosis is a highly prevalent gynecological disease with severe negative impacts on life quality and financial burden. Unfortunately, there is no cure for this disease, which highlights the need for further investigation about the pathophysiology of this disease to provide clues for developing novel therapeutic regimens. Herein, we identified that vascular endothelial growth factor (VEGF)-C, a potent lymphangiogenic factor, is up-regulated in endometriotic cells and contributes to increased lymphangiogenesis. Bioinformatic analysis and molecular biological characterization revealed that VEGF-C is negatively regulated by an orphan nuclear receptor, chicken ovalbumin upstream promoter-transcription factor II (COUP-TFII). Further studies demonstrated that proinflammatory cytokines, via suppression of COUP-TFII level, induce VEGF-C overexpression. More importantly, we show that functional VEGF-C is transported by extracellular vesicles (EVs) to enhance the lymphangiogenic ability of lymphatic endothelial cells. Autotransplanted mouse model of endometriosis showed lenvatinib treatment abrogated the increased lymphatic vessels development in the endometriotic lesion, enlarged retroperitoneal lymph nodes, and immune cells infiltration, indicating that blocking VEGF-C signaling can reduce local chronic inflammation and concomitantly endometriosis development. Evaluation of EV-transmitted VEGF-C from patients' sera demonstrates it is a reliable noninvasive way for clinical diagnosis. Taken together, we identify the vicious cycle of inflammation, COUP-TFII, VEGF-C, and lymphangiogenesis in the endometriotic microenvironment, which opens up new horizons in understanding the pathophysiology of endometriosis. VEGF-C not only can serve as a diagnostic biomarker but also a molecular target for developing therapeutic regimens.

Estrogen-regulated CD200 inhibits macrophage phagocytosis in endometriosis

OBJECTIVES

Endometriosis (EMS) is a benign disease that is related to estrogen, immune disorders and inflammation. The purpose of this research was to determine the expression of CD200 in EMS and to clarify its role in the pathogenesis of the disease.

METHODS

The levels of serum CD200 in patients with and without EMS were determined by ELISA. Furthermore, the expression of CD200 in normal eutopic endometrium and ectopic endometrium was detected by immunohistochemistry and western blotting. The CD200 receptor (CD200R) in macrophages in peritoneal fluid (pMØ) obtained from controls and patients with EMS was examined by western blotting. CD200 expression in human endometrial stromal cells (HESCs) stimulated with 17β-estradiol (E₂) was measured by western blotting. Furthermore, macrophages were stimulated with different concentrations of CD200 and the effect on phagocytosis was analyzed.

RESULTS

The plasma CD200 levels of patients with EMS was significantly increased compared with controls (P = 0.0173, 95%CI [18.75, 159.6]). Compared with normal eutopic endometrium, the expression of CD200 was significantly increased in ectopic endometrial tissues. The CD200R expression in pMØ obtained from patients with EMS was increased compared with the controls (P = 0.0244). CD200 expression in HESCs stimulated with E₂ was up-regulated. As the levels of CD200 increased, macrophage phagocytosis in vitro gradually decreased.

CONCLUSIONS

CD200 is an estrogen-induced molecule that impairs macrophage phagocytosis and may contribute to the immune escape of ectopic lesions in EMS.

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.

Endometriotic Peritoneal Fluid Promotes Myofibroblast Differentiation of Endometrial Mesenchymal Stem Cells

During the development of endometriosis, the presence of fibrotic tissues in and surrounding endometriotic lesions may lead to subsequent adhesion, anatomic distortion, and chronic pain. Therefore, studies aimed at clarifying the underlying mechanisms of fibrogenesis in endometriosis could potentially provide a novel strategy for effective treatment. Mesenchymal stem cells (MSCs) play a key role in fibrotic diseases by differentiating into myofibroblasts in appropriate microenvironment. In this study, we collected endometrial and endometriotic tissues from patients with endometriosis (n = 32) and control patients without endometriosis (n = 20) to compare the expression of fibrotic proteins and investigate the effect of endometriotic peritoneal fluid (PF) on myofibroblast differentiation of endometrial MSCs. We found that the expression of fibrotic proteins, including alpha-smooth muscle actin (α-SMA), type I collagen (collagen I), connective tissue growth factor (CTGF), and fibronectin, and the extent of fibrosis extremely enhanced in ectopic endometria compared with eutopic endometria from the same patients with endometriosis and normal endometria from patients without endometriosis. We next isolated and identified endometrial MSCs and found that treatment with endometriotic PF strongly induced endometrial MSCs to differentiate into myofibroblasts concomitant with the activation of Smad2/3. Moreover, ectopic endometrial MSCs expressed elevated collagen I, α-SMA, fibronectin, and CTGF. Sushi domain containing-2 (SUSD2), a marker of endometrial MSCs, and α-SMA, a well-recognized marker for myofibroblasts, colocalized extensively in ectopic endometria while seldom in normal and eutopic endometria. These findings suggest that ectopic endometrial MSCs are probably more susceptible to myofibroblast differentiation because of the long-term influence of endometriotic PF. All together, we report for the first time that endometriotic PF promotes myofibroblast differentiation of endometrial MSCs. This understanding will greatly improve our understanding of the pathophysiology of endometriosis and help design better therapeutics.

Eutopic endometrium from patients with endometriosis modulates the expression of CD36 and SIRP-α in peritoneal macrophages

Aim

This study aimed to investigate the in vitro alterations of the expression of signal regulatory protein‐α (SIRP‐α) and CD36 in macrophages in the endometriosis condition.

Methods

The expression of SIRP‐α and CD36 was measured in peritoneal macrophages and peripheral blood mononuclear cells of endometriosis patients and control participants. The expressions of SIRP‐α and CD36 were measured in human acute monocytic leukemia (THP‐1) cell‐derived macrophages that were treated with interleukin‐6 (IL‐6)‐induced conditioned medium, eutopic versus normal endometrial homogenate, or lipopolysaccharide in the presence or absence of nuclear factor kappa‐B (NF‐κB) or transforming growth factor (TGF‐β) inhibitors, respectively.

Results

Peritoneal macrophages that were isolated from women with endometriosis exhibited an enhanced expression of SIRP‐α and a decreased expression of CD36 compared to control participants. Women with endometriosis had significantly higher levels of SIRP‐α and CD36 in peripheral circulating mononuclear cells than in control participants. SIRP‐α expression was significantly increased, whereas the CD36 expression was decreased in THP‐1 cell‐derived macrophages after treatment with eutopic endometrial homogenate. Intervention with IL‐6‐induced conditioned medium resulted in the downregulation of SIRP‐α but the upregulation of CD36 in THP‐1 cells. Incubation with the NF‐κBp50 inhibitor decreased the expression of CD36 and SIRP‐α in macrophages that were treated with normal endometrial homogenate, whereas the TGF‐β inhibitor enhanced the CD36 expression of THP‐1 cell‐derived macrophages treated with eutopic endometrial homogenate.

Conclusion

The eutopic endometrium could reduce the phagocytic ability of peritoneal macrophages in women with endometriosis through the modulation of SIRP‐α and CD36 expression. Inhibition of the TGF‐β signal pathway may be a potential therapeutic target for the treatment of endometriosis.

Implication of oxidative stress in the pathogenesis of systemic sclerosis via inflammation, autoimmunity and fibrosis

Systemic sclerosis is an autoimmune disorder characterized by inflammation and a progressive fibrosis affecting the skin and visceral organs. Over the last two decades, it became clear that oxidative stress plays a key role in its pathogenesis. In this review, we highlighted the role of ROS in the various pathological components of systemic sclerosis, namely the inflammatory, the autoimmune and the fibrotic processes. We also discussed how these pathological processes can induce ROS overproduction, thus maintaining a vicious circle. Finally, we summarized the therapeutic approaches targeting oxidative stress tested in systemic sclerosis, in cells, animal models and patients.

Hypoxia: The force of endometriosis

AIM

Summarize recent findings of how hypoxia regulates numerous important processes to facilitate the implantation, proliferation and progression of ectopic endometriotic lesions.

METHODS

Most up-to-date evidences about how hypoxia contributes to the disease pathogenesis of endometriosis and potential therapeutic approaches were collected by conducting a comprehensive search of medical literature electronic databases. Quality of data was analyzed by experienced experts including gynecologist and basic scientists.

RESULTS

Uterus is a highly vascularized organ, which makes endometrial cells constantly expose to high concentration of oxygen. When endometrial tissues shed off from the eutopic uterus and retrograde to the peritoneal cavity, they face severe hypoxic stress. Even with successful implantation to ovaries or peritoneum, the hypoxic stress remains as a critical issue because endometrial cells are used to live in the well-oxygenated environment. Under the hypoxia condition, cells undergo epigenetic modulation and evolve several survival processes including steroidogenesis, angiogenesis, inflammation and metabolic switch. The complex gene regulatory network driven by hypoxia ensures endometriotic cells can survive under the hostile peritoneal microenvironment.

CONCLUSION

Hypoxia plays critical roles in promoting pathological processes to facilitate the development of endometriosis. Targeting hypoxia-mediated gene network represents an alternative approach for the treatment of endometriosis.

Regulation of Inflammation Pathways and Inflammasome by Sex Steroid Hormones in Endometriosis

Endometriosis is a gynecological disorder characterized by the growth of endometrial tissue (glands and stroma) outside the uterus, mainly in the peritoneal cavity, ovaries, and intestines. This condition shows estrogen dependency and progesterone resistance, and it has been associated with chronic inflammation, severe pain, and infertility, which negatively affect the quality of life in reproductive women. The molecular mechanisms involved in the pathogenesis of endometriosis are not completely understood; however, inflammation plays a key role in the pathophysiology of the disease, mainly by altering the function of immune cells (macrophages, natural killer, and T cells) and increasing levels of pro-inflammatory mediators in the peritoneal cavity, endometrium, and blood. These immune alterations inhibit apoptotic pathways and promote adhesion and proliferation of endometriotic cells, as well as angiogenesis and neurogenesis in endometriotic lesions. It has been demonstrated that hormonal alterations in endometriosis are related to the inflammatory unbalance in this disease. Particularly, steroid hormones (mainly estradiol) promote the expression and release of pro-inflammatory factors. Excessive inflammation in endometriosis contributes to changes of hormonal regulation by modulating sex steroid receptors expression and increasing aromatase activity. In addition, dysregulation of the inflammasome pathway, mediated by an alteration of cellular responses to steroid hormones, participates in disease progression through preventing cell death, promoting adhesion, invasion, and cell proliferation. Furthermore, inflammation is involved in endometriosis-associated infertility, which alters endometrium receptivity by impairing biochemical responses and decidualization. The purpose of this review is to present current research about the role of inflammasome in the pathogenesis of endometriosis as well as the molecular role of sex hormones in the inflammatory responses in endometriosis.

Innate Immune Cells: Gatekeepers of Endometriotic Lesions Growth and Vascularization

Infiltration by inflammatory leukocytes is a hallmark of all forms of endometriosis. Conversely, the innate immune system plays a key role in regulating events such as cell adhesion, migration, survival and neoangiogenesis of transformed or ectopic tissue. All these features are involved, and possibly required, in the development of endometriotic lesions. Recent data suggest that infiltrating leukocytes are not a mere epiphenomenon but represent an actual requirement for the development of the disease. In this scenario, the functional plasticity of infiltrating macrophages is a key event in the origin and maintenance of endometriotic lesions: the erroneous polarization of macrophages towards cells sustaining angiogenesis and tissue remodeling represents a potential target for novel molecular therapies.

Retinoid Metabolism in Endometriosis

Endometriosis is an estrogen-dependent disease in which progesterone resistance and inflammation have been found to be major mechanisms responsible for its development and progression. When compared to eutopic endometrium, key molecules have been found to be differentially expressed, which contribute to these mechanisms. One pathway that is aberrant in endometriotic tissue when compared to eutopic endometrium is the retinoic acid signaling pathway. This review focuses on the role of the retinoid signaling pathway in endometriosis and summarizes evidence that supports the use of retinoid compounds for the stimulation of pro-apoptotic activity in these cells.

Targeting hypoxia-mediated YAP1 nuclear translocation ameliorates pathogenesis of endometriosis without compromising maternal fertility

Endometriosis is a highly prevalent gynaecological disease that severely reduces women's health and quality of life. Ectopic endometriotic lesions have evolved mechanisms to survive in the hypoxic peritoneal microenvironment by regulating the expression of a significant subset of genes. However, the master regulator controlling these genes remains to be characterized. Herein, by using bioinformatics analysis and experimental verification, we identified yes-associated protein 1 (YAP1) as a master regulator of endometriosis. Nuclear localization and transcriptional activity of YAP1 were up-regulated by hypoxia via down-regulation of LATS1, a kinase that inactivates YAP1. Disruption of hypoxia-induced YAP1 signalling by siRNA knockdown or inhibitor treatment abolished critical biological processes involved in endometriosis development such as steroidogenesis, angiogenesis, inflammation, migration, innervation, and cell proliferation. Treatment with a YAP1 inhibitor caused the regression of endometriotic lesions without affecting maternal fertility or the growth rate of offspring in the mouse model of endometriosis. Taken together, we identify hypoxia/LATS1/YAP1 as a novel pathway for the pathogenesis of endometriosis and demonstrate that targeting YAP1 might be an alternative approach to treat endometriosis. Copyright © 2017 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

Immunosuppressive macrophages induced by IDO1 promote the growth of endometrial stromal cells in endometriosis

It was previously demonstrated that anomalous expression of indoleamine 2,3-dioxygenase-1 (IDO1) in endometrial stromal cells (ESCs) stimulated an inflammatory response that subsequently initiated the activation of immunosuppressive macrophages in endometriosis. The aim of the present study was to clarify the effect of IDO1‑induced macrophages on the growth of ESCs in endometriosis. Normal ESCs, ectopic ESCs and normal ESCs treated with plasmid pEGFP‑N1‑IDO1 or SD11‑IDO1 short hairpin RNA were co‑cultured with peripheral blood‑derived monocyte (PBMC)‑driven macrophages directly for 48 h. Compared with normal ESCs, the PBMC‑driven macrophages that were co‑cultured with ectopic ESCs displayed a lower phagocytic ability. pEGFP‑N1‑IDO1 transfection of normal ESCs also decreased the phagocytic ability of co‑cultured macrophages. Additionally, pEGFP‑N1‑IDO1‑transfected ESC‑induced macrophages significantly increased the viability and proliferation of ESCs, while ESC apoptosis was decreased, compared with control ESCs. In conclusion, IDO1 educated-macrophages may facilitate the survival of retrograde endometrial tissues, and be involved in the pathogenesis of endometriosis.

Co-micronized Palmitoylethanolamide/Polydatin Treatment Causes Endometriotic Lesion Regression in a Rodent Model of Surgically Induced Endometriosis

Endometriosis is a chronic, painful disease characterized by the presence of endometrial glands and stroma outside the uterine cavity. Palmitoylethanolamide (PEA), an endogenous fatty acid amide, has anti-inflammatory and neuroprotective effects. PEA lacks free radical scavenging activity, unlike polydatin (PLD), a natural precursor of resveratrol. The aim of this study was to investigate the effect of orally administered co-micronized PEA/polydatin [m(PEA/PLD)] in an autologous rat model of surgically induced endometriosis. Endometriosis was induced in female Wistar albino rats by auto-transplantation of uterine squares (implants) into the intestinal mesentery and peritoneal cavity. Rats were distributed into one control group and one treatment group (10 animals each): m(PEA/PLD) 10 mg/kg/day. At 28 days after surgery the relative volume of the endometrioma was determined. Endometrial-like tissue was confirmed by histology: Masson trichrome and toluidine blue were used to detect fibrosis and mast cells, respectively. The treated group displayed a smaller cyst diameter, with improved fibrosis score and mast cell number decrease. m(PEA/PLD) administration decreased angiogenesis (vascular endothelial growth factor), nerve growth factor, intercellular adhesion molecule, matrix metalloproteinase 9 expression, and lymphocyte accumulation. m(PEA/PLD) treatment also reduced peroxynitrite formation, (poly-ADP)ribose polymerase activation, IkBα phosphorylation and nuclear facor-kB traslocation in the nucleus. Our results suggested that m(PEA/PLD) may be of use to inhibit development of endometriotic lesions in rats.

MAP kinases and the inflammatory signaling cascade as targets for the treatment of endometriosis?

INTRODUCTION

The pathogenesis of endometriosis, a common benign disease, remains ill-defined, although it is clear that chronic inflammation plays a crucial role through mitogen-activated protein kinase (MAPK) signaling pathways. All current medical therapies for endometriosis are antigonadotropic, and therefore have a contraceptive effect. A concerted research effort is hence warranted with the aim of delivering novel therapeutics that reduces disease symptoms without blocking ovulation.

AREAS COVERED

The authors review the complex pathogenic mechanisms of chronic inflammation in endometriosis and their relationships with MAPK pathways. The authors conducted a literature search of descriptive and functional targeted validation of MAPK in the pathogenesis of endometriosis. The effects of MAPK inhibitors, which constitute potential agents for future treatments, are also described.

EXPERT OPINION

Preliminary studies have highlighted a crucial role for MAPK in driving endometriosis-related inflammation. MAPK inhibitors exhibit potent activity in terms of controlling growth of endometriosis lesions both in vitro and in animal models. As MAPK inhibitors are known to have a multitude of undesirable side effects, their use in humans has to be approached with great care. Indeed, use of these drugs would probably be limited to short exposures prior to surgery in cases involving the most severe disease phenotypes.

Immunological aspects of endometriosis: a review

Endometriosis is a common and serious illness affecting women in their reproductive years. Despite the ongoing interest and intensive research of this crippling disease, the cause remains unknown since its first description over 150 years ago. The origins and genesis of endometriosis, despite numerous hypotheses, are still unclear. One of the possible causes of the development of endometriosis might be the immune system, despite the fact that endometriosis is generally considered to be a steroid-sensitive disease. Numerous aspects of the immune system has been found changed, from the different number of activated macrophages to different subtypes of lymphocytes and their activities, suggesting involvement of immunity. On the other hand, it is possible that immunological changes around the endometriotic lesion are only secondary to the establishment of endometriosis. In this review, we will summarize the current knowledge of immunological reactions in endometriosis.

Pathogenetic Mechanisms of Deep Infiltrating Endometriosis

Endometriosis is a benign gynecologic disease, affecting women of reproductive age associated with chronic pelvic pain, dysmenorrhea, dyspareunia and infertility. Ovarian endometrioma (OMA), superficial peritoneal endometriosis (SPE), and deep infiltrating endometriosis (DIE) are, till now, recognized as major phenotypes. The discussion is to know whether they share the same pathogenetic mechanisms. Till today, DIE is recognized as the most severe clinical form of endometriosis and has a complex clinical management. The DIE lesions have been considered in the present article, without distinguishing between the anterior (bladder) or the posterior (vagina, uterosacral ligaments, rectum, and ureter) compartment. The present knowledge indicates that hormonal function (estrogen and progesterone receptors) and immunological factors, such as peritoneal macrophages, natural killer cells, and lymphocytes, are critically altered in DIE. The aggressive behavior of DIE may be explained by the highly decreased apoptosis (nuclear factor kappa-light-chain-enhancer of activated B cells [NF-kB], B-cell lymphoma 2 [Blc-2], and anti-Mullerian hormone) and by the increased proliferation activity related to oxidative stress (NF-kB, reactive oxygen species, extracellular regulated kinase (ERK), advanced oxidation protein product). Invasive mechanisms are more expressed (matrix metalloproteinases and activins) in DIE in comparison to the OMA and SPE. Correlated with the increased invasiveness are the data on very high expression of neuroangiogenesis (nerve growth factor, vascular endothelial growth factor, and intercellular adhesion molecule) genes in DIE. Therefore, at the present time, several of the DIE pathogenetic features result specific in comparison to other endometriosis phenotypes, pleading for the existence of a specific entity. These evidence of specific pathogenetic features of DIE may explain the more severe symptomatology related to this form of endometriosis and suggest possible future target medical treatments.

Targeting CD13 (aminopeptidase-N) in turn downregulates ADAM17 by internalization in acute myeloid leukaemia cells

Secreted matrix metalloproteinases (MMP)-2 and MMP-9 and membrane-anchored aminopeptidase-N/CD13 are abnormally expressed in human acute myeloid leukaemia (AML). We previously showed that CD13 ligation by anti-CD13 monoclonal antibodies can induce apoptosis in AML cells. Here, we assessed ADAM17 expression in primary blood blasts CD13⁺CD33⁺ from patients with AML. Primary AML cells expressed ADAM17 transcript and its surface expression was higher in subtype M4 (myelomonocytic) and M5 (monocytic) AML specimens than in M0 and M1/M2 (early and granulocytic) specimens. In AML cell lines defining distinct AML subfamilies (HL-60/M2, NB4/M3, THP-1/M5, U937/M5) and primary AML cells cultured ex vivo, anti-CD13 antibodies downregulated surface CD13 and ADAM17 without affecting MMP-2/-9 release. Knockdown of CD13 by siRNA prevented anti-CD13-mediated ADAM17 downregulation, indicating that CD13 is required for ADAM17 downregulation. Soluble ADAM17 was not detected in the medium of anti-CD13 treated cells, suggesting that ADAM17 was not shed. After ligation by anti-CD13, CD13 and ADAM17 were internalized. Subsequently, we found that ADAM17 interacts with CD13. We postulate that the interaction of ADAM17 with CD13 and its downregulation following CD13 engagement has important implications in AML for the known roles of ADAM17 in tumour-associated cell growth, migration and invasion.

Effect of the non-specific matrix metalloproteinase inhibitor Doxycycline on endometriotic implants in an experimental rat model

The aim of this study was to investigate the possible therapeutic effects of Doxycycline (Dox) on endometriotic lesions in an experimental rat model. Thirty-seven female Wistar albino rats with surgically induced endometriosis were randomized and divided into four groups. The rats were administered 5 mg/kg/day oral Dox in Group 1 (low-dose Dox group, n=9), 20 mg/kg/day oral Dox in Group 2 (high-dose Dox group, n=10) and 1 mg/kg single dose, subcutaneous leuprolide acetate in Group 3 (leuprolide acetate group, n=9). The rats in Group 4 (control group, n=9) were given no medication. The rats received medication for three weeks and were then sacrificed to evaluate the morphological and histological features of the implants. Matrix metalloproteinase (MMP)-9 immunoreactivity of the implants was also evaluated. The size of the endometriotic implants decreased in Groups 1-3 but statistically significant differences were not observed among the groups. The mean surface area of the endometriotic implants decreased from 69.3±30.8 to 52.1±27.0 mm² in Group 1 (P>0.05), from 60.2±18.9 to 38.6±28.7 mm² in Group 2 (P>0.05) and from 58.1±33.1 to 26±9.0 mm² in Group 3 (P=0.03). The epithelial MMP-9 immunohistochemical score was significantly higher in Group 1 and lower in Group 3 when compared with the control group (Group 4) (P=0.042 and P=0.014, respectively). When the stromal MMP-9 immunohistochemical and histopathological scores of the endometriotic implants were compared, no statistically significant differences were found among the groups. Although there was no statistically significant difference, Dox reduced the endometriotic implant area in the rat endometriosis model. Further studies are required to investigate the potential efficacy of Dox in endometriosis due to its widespread use and tolerability.

CD4+Foxp3+ regulatory T cell differentiation mediated by endometrial stromal cell-derived TECK promotes the growth and invasion of endometriotic lesions

Endometriosis is associated with an abnormal immune response to endometrial cells, which can facilitate the implantation and proliferation of ectopic endometrial tissue. The proportion of CD4(+)Foxp3(+) regulatory T cells (Tregs) is significantly increased in the peritoneal fluid of women with endometriosis. The thymus-expressed chemokine TECK/CCL25 directly promotes the invasiveness of endometrial stromal cells (ESCs). The aim of this study was to investigate the effects of ESC-derived TECK on the crosstalk between Tregs and ESCs in the progress of endometriosis. We determined that the percentage of Tregs and the concentration of TECK increased in the peritoneal fluid with the progression of endometriosis. The supernatant from co-cultured human ESCs and macrophages not only induced Treg differentiation and increased Treg expression of interleukin-10 (IL-10), transforming growth factor-β (TGF-β) and CD73 by activating the AKT/STAT3 signaling pathway but also repressed Treg apoptosis by downregulating Fas and FasL expression and enhanced the Treg-mediated suppression of CD4(+)CD25(-) T cells. In addition, in vitro and in vivo trials confirmed that these effects could be inhibited by anti-TECK neutralizing Abs. The secretion of IL-10 and TGF-β by Tregs increased MMP2 expression and decreased TIMP1 expression and further stimulated the proliferation and invasion of ESCs and the growth of ectopic lesions. These results indicate that TECK derived from ESCs and macrophages upregulates the number and function of Tregs in the ectopic milieu, which contributes to endometriotic immunotolerance and high levels of ESC proliferation and invasion, thereby facilitating the progression of endometriosis.

Indoleamine 2,3-dioxygenase-1 (IDO1) in human endometrial stromal cells induces macrophage tolerance through interleukin-33 in the progression of endometriosis

In the peritoneal fluid, macrophages and their secretory cytokines are essential for endometriosis, but the factors that favor their involvement in the endometriosis-associated inflammatory response are still elusive. Given the anomalous expression of indoleamine 2,3-dioxygenase-1 (IDO1) in endometrial stromal cells (ESCs) and its potentially important roles in immune modulation, we aimed to determine the effects of IDO1 in ESCs on macrophages and the mechanism of those effects. Normal ESCs and ectopic ESCs transfected with the SD11-IDO1 shRNA (short hairpin RNA) or vector-only plasmid SD11 were subsequently co-cultured with peripheral blood (PB)-derived monocytes (PBMC)-driven macrophages directly and indirectly. Cytokine production was determined by analyzing the supernatant of the co-culture unit by enzyme-linked immunosorbent assay (ELISA). The phenotypes and the phagocytic ability of the macrophages were determined by flow cytometry. Compared to normal ESCs, the PBMC-driven macrophages co-cultured with ectopic ESCs displayed lower phagocytic ability. Additionally, macrophages co-cultured with ectopic ESCs exhibited higher levels of CD163 and CD209 and lower levels of HLA-DR and CD11c. Moreover, both the intracellular expression and extracellular secretion of interleukin-10 (IL-10) and transforming growth factor-β1 (TGF-β1) were significantly increased, while that of IL-12p70 was decreased in macrophages after being co-cultured with ectopic ESCs. However, there was no significant difference in macrophage phagocytic ability, immunophenotype or cytokine secretion between the direct and indirect co-culture units. Reversely, SD11-IDO1 shRNA transfection of ectopic ESCs could abrogate the decreased phagocytic ability and alternative activation of macrophages in ectopic ESC-macrophage co-culture unit, suggesting that higher IDO1 in ectopic ESCs was indispensable for the induction of macrophage tolerance. Furthermore, the decrease in phagocytic macrophages and alternatively activated macrophages induced by IDO1 in ectopic ESCs was reversed by the addition of an IL-33 inhibitor, that is, soluble ST2 (sST2). Therefore, through the activation of IL-33, the increased expression of IDO1 in ectopic ESCs contributed to the truncated phagocytic ability of macrophages in endometriosis.

Lipoxin A₄ prevents the progression of de novo and established endometriosis in a mouse model by attenuating prostaglandin E₂ production and estrogen signaling

Endometriosis, a leading cause of pelvic pain and infertility, is characterized by ectopic growth of endometrial-like tissue and affects approximately 176 million women worldwide. The pathophysiology involves inflammatory and angiogenic mediators as well as estrogen-mediated signaling and novel, improved therapeutics targeting these pathways are necessary. The aim of this study was to investigate mechanisms leading to the establishment and progression of endometriosis as well as the effect of local treatment with Lipoxin A₄ (LXA₄), an anti-inflammatory and pro-resolving lipid mediator that we have recently characterized as an estrogen receptor agonist. LXA₄ treatment significantly reduced endometriotic lesion size and downregulated the pro-inflammatory cytokines IL-1β and IL-6, as well as the angiogenic factor VEGF. LXA₄ also inhibited COX-2 expression in both endometriotic lesions and peritoneal fluid cells, resulting in attenuated peritoneal fluid Prostaglandin E₂ (PGE₂) levels_. Besides its anti-inflammatory effects, LXA₄ differentially regulated the expression and activity of the matrix remodeling enzyme matrix metalloproteinase (MMP)-9 as well as modulating transforming growth factor (TGF)-β isoform expression within endometriotic lesions and in peritoneal fluid cells. We also report for first time that LXA₄ attenuated aromatase expression, estrogen signaling and estrogen-regulated genes implicated in cellular proliferation in a mouse model of disease. These effects were observed both when LXA₄ was administered prior to disease induction and during established disease. Collectively, our findings highlight potential targets for the treatment of endometriosis and suggest a pleotropic effect of LXA₄ on disease progression, by attenuating pro-inflammatory and angiogenic mediators, matrix remodeling enzymes, estrogen metabolism and signaling, as well as downstream proliferative pathways.

Different effects of the immunomodulatory drug GMDP immobilized onto aminopropyl modified and unmodified mesoporous silica nanoparticles upon peritoneal macrophages of women with endometriosis

The aim of the present work was to compare in vitro the possibility of application of unmodified silica nanoparticles (UMNPs) and modified by aminopropyl groups silica nanoparticles (AMNPs) for topical delivery of immunomodulatory drug GMDP to the peritoneal macrophages of women with endometriosis. The absence of cytotoxic effect and high cellular uptake was demonstrated for both types of silica nanoparticles. The immobilization of GMDP on the UMNPs led to the suppression of the stimulatory effect of GMDP on the membrane expression of scavenger receptors SR-AI and SR-B, mRNAs expression of NOD2 and RAGE, and synthesis of proteolytic enzyme MMP-9 and its inhibitor TIMP-1. GMDP, immobilized onto AMNPs, enhanced the initially reduced membrane expression of SRs and increased NOD2, RAGE, and MMP-9 mRNAs expression by macrophages. Simultaneously high level of mRNAs expression of factors, preventing undesirable hyperactivation of peritoneal macrophages (SOCS1 and TIMP-1), was observed in macrophages incubated in the presence of GMDP, immobilized onto AMNPs. The effect of AMNPs immobilized GMDP in some cases exceeded the effect of free GMDP. Thus, among the studied types of silica nanoparticles, AMNPs are the most suitable nanoparticles for topical delivery of GMDP to the peritoneal macrophages.

The M2 polarization of macrophage induced by fractalkine in the endometriotic milieu enhances invasiveness of endometrial stromal cells

Fractalkine (FKN) is involved in the immunopathogenesis of inflammatory diseases, including endometriosis. Our objective was to investigate the role of FKN in the cross-talking between endometrial stromal cells (ESCs) and U937 (macrophage line) in the endometriotic milieu. We have found that FKN levels in peritoneal fluid and ESCs positively correlate with the progress of endometriosis. The expression of CX3CR1 in the normal ESCs were significantly lower than that in eutopic and ectopic ESCs from women with endometriosis. CX3CR1 expression in U937 was higher than that in ectopic ESCs. FKN secreted by eutopic ESCs could change the balance between the release of IL10 and IL12 of macrophages with the upregulation of IL10 production and downregulation of IL12 production. Moreover, FKN could induce M2 polarization of macrophage with decreased expression of CD86. FKN could increase the expression of matrix metalloproteinase 9 and decrease the expression of tissue inhibitor of metalloproteinase1 and 2, and promote the invasiveness of ESCs by activating p38MAPK and integrinβ1 signal pathway. In conclusion, the higher levels of FKN secreted by eutopic ESCs facilitate the onset and progression of endometriosis by inducing M2 polarization of macrophage which in turn enhances invasiveness of ESCs.

Medical management of endometriosis: emerging evidence linking inflammation to disease pathophysiology

Progesterone action normally mediates the balance between anti-inflammatory and proinflammatory processes throughout the female reproductive tract. However, in women with endometriosis, endometrial progesterone resistance, characterized by alterations in progesterone responsive gene and protein expression, is now considered a central element in disease pathophysiology. Recent studies additionally suggest that the peritoneal microenvironment of endometriosis patients exhibits altered physiological characteristics that may further promote inflammation-driven disease development and progression. Within this review, we summarize our current understanding of the pathogenesis of endometriosis with an emphasis on the role that inflammation plays in generating not only the progesterone-resistant eutopic endometrium but also a peritoneal microenvironment that may contribute significantly to disease establishment. Viewing endometriosis from the emerging perspective that a progesterone resistant endometrium and an immunologically compromised peritoneal microenvironment are biologically linked risk factors for disease development provides a novel mechanistic framework to identify new therapeutic targets for appropriate medical management.

Atypical Expression of COX-2, StAR, CYP19A1 and Apoptotic Regulators in CD90 Positive Endometrial Stromal Cells from Women with Endometriosis

Purpose

Endometriosis is an invasive gynecologic disease characterized by diminished apoptosis, sustained ectopic survival of dysfunctional endometrial cells and implantation of endometriotic lesions outside of the uterus. The purpose of this investigation was to determine the expression pattern of apoptotic and steroidogenic genes in the progenitor stem cell population of eutopic tissues from women with endometriosis and compare them to controls. The expression of these genes was determined in a subpopulation of endometrial cells that displayed CD90 positivity (CD+ve90) and colony forming capacity.

Methods

We obtained endometrial samples from women with or without endometriosis. Endometrial stromal cells (ESCs) were isolated and cultured for 15 days. Purified ESCs were sorted by using a multipotent mesenchymal stromal cell multi-color flow cytometry kit. Single cell cloning was performed by serial dilution in 96-micro well plates. Fifteen days later, colonies were identified (CFUs). The colonies were chosen and cultured. mRNA expression of apoptotic genes, mitogen activated kinase 14 (MAPK14), nuclear factor kappa B (NFkB), steroidogenic acute regulatory protein (StAR), aromatase (CYP19A1) and cyclo-oxygenase-2 (COX-2) were determined by qRT-PCR. Protein levels of StAR, CYP19A1 and COX-2 were determined by western blotting.

Results

A subset of stromal cells derived from women with endometriosis were isolated and identified as progenitor stem cells based on their CD90 positivity and colony forming ability. The cells displayed increased levels of MAPK14, NFkB, COX-2, StAR and CYP19A1 both at the mRNA and protein level compared to stromal cells derived from controls. Similarly, pro-apoptotic molecules such as Bax were decreased whereas anti-apoptotic molecules such as Bcl2 were decreased at the mRNA level compared to stromal cells derived from controls.

Conclusions

CD90+ve ESCs derived from women with endometriosis displayed markers suggesting stem cell-like properties and aberrant expression of apoptotic and steroidogenic enzymes which may contribute to sustained survival of these cells.

Augmented epithelial multidrug resistance-associated protein 4 expression in peritoneal endometriosis: regulation by lipoxin A(4)

OBJECTIVE

To compare the expression of the prostaglandin (PG) E(2) transporter multidrug resistance-associated protein 4 (MRP4) in eutopic and ectopic endometrial tissue from endometriosis patients with that of control subjects and to examine whether MRP4 is regulated by the antiinflammatory lipid lipoxin A(4) (LXA(4)) in endometriotic epithelial cells.

DESIGN

Molecular analysis in human samples and a cell line.

SETTING

Two university hospitals and a private clinic.

PATIENT(S)

A total of 59 endometriosis patients and 32 age- and body mass index-matched control subjects undergoing laparoscopy or hysterectomy.

INTERVENTION(S)

Normal, eutopic, and ectopic endometrial biopsies as well as peritoneal fluid were obtained during surgery performed during the proliferative phase of the menstrual cycle. 12Z endometriotic epithelial cells were used for in vitro mechanistic studies.

MAIN OUTCOME MEASURE(S)

Tissue MRP4 mRNA levels were quantified by quantitative reverse-transcription polymerase chain reaction (qRT-PCR), and localization was analyzed with the use of immunohistochemistry. Cellular MRP4 mRNA and protein were quantified by qRT-PCR and Western blot, respectively. PGE(2) was measured in peritoneal fluid and cell supernatants using an enzyme immunoassay (EIA).

RESULT(S)

MRP4 was expressed in eutopic and ectopic endometrium, where it was overexpressed in peritoneal lesions and localized in the cytoplasm of glandular epithelial cells. LXA(4) attenuated MRP4 mRNA and protein levels in endometriotic epithelial cells in a dose-dependent manner, while not affecting the expression of enzymes involved in PGE(2) metabolism. Investigations employing receptor antagonists and small interfering RNA revealed that this occurred through estrogen receptor α. Accordingly, LXA(4) treatment inhibited extracellular PGE(2) release.

CONCLUSION(S)

We report for the first time that MRP4 is expressed in human endometrium, elevated in peritoneal endometriosis, and modulated by LXA(4) in endometriotic epithelial cells.

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.

Endometriosis, a disease of the macrophage

Endometriosis, a common cause of pelvic pain and female infertility, depends on the growth of vascularized endometrial tissue at ectopic sites. Endometrial fragments reach the peritoneal cavity during the fertile years: local cues decide whether they yield endometriotic lesions. Macrophages are recruited at sites of hypoxia and tissue stress, where they clear cell debris and heme-iron and generate pro-life and pro-angiogenesis signals. Macrophages are abundant in endometriotic lesions, where are recruited and undergo alternative activation. In rodents macrophages are required for lesions to establish and to grow; bone marrow-derived Tie-2 expressing macrophages specifically contribute to lesions neovasculature, possibly because they concur to the recruitment of circulating endothelial progenitors, and sustain their survival and the integrity of the vessel wall. Macrophages sense cues (hypoxia, cell death, iron overload) in the lesions and react delivering signals to restore the local homeostasis: their action represents a necessary, non-redundant step in the natural history of the disease. Endometriosis may be due to a misperception of macrophages about ectopic endometrial tissue. They perceive it as a wound, they activate programs leading to ectopic cell survival and tissue vascularization. Clearing this misperception is a critical area for the development of novel medical treatments of endometriosis, an urgent and unmet medical need.