Proangiogenetic molecules, hypoxia-inducible factor-1α and nitric oxide synthase isoforms in ovarian endometriotic cysts

Cannabidiol as a possible treatment for endometriosis through suppression of inflammation and angiogenesis

BACKGROUND

Endometriosis is associated with a wide variety of signs and symptoms and can lead to infertility, embryo death, and even miscarriage. Although the exact pathogenesis and etiology of endometriosis is still unclear, it has been shown that it has a chronic inflammatory nature and angiogenesis is also involved in it.

OBJECTIVE

This review aims to explore the role of inflammation and angiogenesis in endometriosis and suggest a potential treatment targeting these pathways.

FINDINGS

Among the pro-inflammatory cytokines, studies have shown solid roles for interleukin 1β (IL-β), IL-6, and tumor necrosis factor α (TNF-α) in the pathogenesis of this condition. Other than inflammation, angiogenesis, the formation of new blood vessels from pre-existing capillaries, is also involved in the pathogenesis of endometriosis. Among angiogenic factors, vascular endothelial growth factor (VEGF), hypoxia-inducible factor 1α (HIF-1α), transforming growth factor β1 (TGF-β1), and matrix metalloproteinases (MMPs) are more essential in the pathogenesis of endometriosis. Interestingly, it has been shown that inflammation and angiogenesis share some similar pathways with each other that could be potentially targeted for treatment of diseases caused by these two processes. Cannabidiol (CBD) is a non-psychoactive member of cannabinoids which has well-known and notable anti-inflammatory and antiangiogenic properties. This agent has been shown to decrease IL-1β, IL-6, TNF-α, VEGF, TGFβ, and MMPs in different animal models of diseases.

CONCLUSION

It seems that CBD could be a possible treatment for endometriosis due to its anti-inflammatory and antiangiogenic activity, however, further studies are needed.

Hypoxia and the endometrium: An indispensable role for HIF-1α as therapeutic strategies

Hypoxia-inducible factor 1 alpha (HIF-1α) is a major molecular mediator of the hypoxic response. In the endometrium, local hypoxic conditions induced by hormonal fluctuations and endometrial vascular remodeling contribute to the production of HIF-1α, which plays an indispensable role in a series of physiological activities, such as menstruation and metamorphosis. The sensitive regulation of HIF-1α maintains the cellular viability and regenerative capacity of the endometrium against cellular stresses induced by hypoxia and excess reactive oxygen species. In contrast, abnormal HIF-1α levels exacerbate the development of various endometrial pathologies. This knowledge opens important possibilities for the development of promising HIF-1α-centered strategies to ameliorate endometrial disease. Nonetheless, additional efforts are required to elucidate the regulatory network of endometrial HIF-1α and promote the applications of HIF-1α-centered strategies in the human endometrium. Here, we summarize the role of the HIF-1α-mediated pathway in endometrial physiology and pathology, highlight the latest HIF-1α-centered strategies for treating endometrial diseases, and improve endometrial receptivity.

Vascularisation in Deep Endometriosis: A Systematic Review with Narrative Outcomes

Deep endometriosis (DE) is the most severe subtype of endometriosis, with the hallmark of lesions infiltrating adjacent tissue. Abnormal vascularisation has been implicated in contributing to endometriosis lesion development in general, and how vascularisation influences the pathogenesis of DE, in particular, is of interest. This systematic review followed the PRISMA guidelines to elucidate and examine the evidence for DE-specific vascularisation. A literature search was performed using MEDLINE, Embase, PubMed, Scopus, Cochrane CENTRAL Library and Europe PubMed Central databases. The databases were searched from inception to the 13 March 2023. A total of 15 studies with 1125 patients were included in the review. The DE lesions were highly vascularised, with a higher microvessel density (MVD) than other types of endometriotic lesions, eutopic endometrium from women with endometriosis and control tissue. Vascular endothelial growth factor, its major subtype (VEGF-A) and associated receptor (VEGFR-2) were significantly increased in the DE lesions compared to superficial endometriosis, eutopic endometrium and control tissue. Progestin therapy was associated with a significant decrease in the MVD of the DE lesions, explaining their therapeutic effect. This review comprehensively summarises the available literature, reporting abnormal vascularisation to be intimately related to the pathogenesis of DE and presents potentially preferential therapeutic targets for the medical management of DE.

Biomechanical forces and signals operating in the ovary during folliculogenesis and their dysregulation: implications for fertility

BACKGROUND

Folliculogenesis occurs in the highly dynamic environment of the ovary. Follicle cyclic recruitment, neo-angiogenesis, spatial displacement, follicle atresia and ovulation stand out as major events resulting from the interplay between mechanical forces and molecular signals. Morphological and functional changes to the growing follicle and to the surrounding tissue are required to produce oocytes capable of supporting preimplantation development to the blastocyst stage.

OBJECTIVE AND RATIONALE

This review will summarize the ovarian morphological and functional context that contributes to follicle recruitment, growth and ovulation, as well as to the acquisition of oocyte developmental competence. We will describe the changes occurring during folliculogenesis to the ovarian extracellular matrix (ECM) and to the vasculature, their influence on the mechanical properties of the ovarian tissue, and, in turn, their influence on the regulation of signal transduction. Also, we will outline how their dysregulation might be associated with pathologies such as polycystic ovary syndrome (PCOS), endometriosis or premature ovarian insufficiency (POI). Finally, for each of these three pathologies, we will highlight therapeutic strategies attempting to correct the altered biomechanical context in order to restore fertility.

SEARCH METHODS

For each area discussed, a systematic bibliographical search was performed, without temporal limits, using PubMed Central, Web of Science and Scopus search engines employing the keywords extracellular matrix, mechanobiology, biomechanics, vasculature, angiogenesis or signalling pathway in combination with: ovary, oogenesis, oocyte, folliculogenesis, ovarian follicle, theca, granulosa, cumulus, follicular fluid, corpus luteum, meiosis, oocyte developmental competence, preimplantation, polycystic ovary syndrome, premature ovarian insufficiency or endometriosis.

OUTCOMES

Through search engines queries, we yielded a total of 37 368 papers that were further selected based on our focus on mammals and, specifically, on rodents, bovine, equine, ovine, primates and human, and also were trimmed around each specific topic of the review. After the elimination of duplicates, this selection process resulted in 628 papers, of which 287 were cited in the manuscript. Among these, 89.2% were published in the past 22 years, while the remaining 8.0%, 2.4% or 0.3% were published during the 1990s, 1980s or before, respectively. During folliculogenesis, changes occur to the ovarian ECM composition and organization that, together with vasculature modelling around the growing follicle, are aimed to sustain its recruitment and growth, and the maturation of the enclosed oocyte. These events define the scenario in which mechanical forces are key to the regulation of cascades of molecular signals. Alterations to this context determine impaired folliculogenesis and decreased oocyte developmental potential, as observed in pathological conditions which are causes of infertility, such as PCOS, endometriosis or POI.

WIDER IMPLICATIONS

The knowledge of these mechanisms and the rules that govern them lay a sound basis to explain how follicles recruitment and growth are modulated, and stimulate insights to develop, in clinical practice, strategies to improve follicular recruitment and oocyte competence, particularly for pathologies like PCOS, endometriosis and POI.

Predictive factors of endometriosis progression into ovarian cancer

BACKGROUND

In recent years, the endometriosis has overcome a noteworthy renaissance in the recognition of its potential. In certain patients, a demonstrable malignant progression of ectopic foci leading to development of ovarian cancer is seen. The knowledge of endometriosis overthrow background into endometriosis associated ovarian cancer is of paramount importance for selection of patients at risk. The goal of the presented study was to review a malignant potential of the endometriosis and to specify predictive factors of endometriosis progression into ovarian cancer. Altogether 189 patients were included in the study. Conventional cytogenetics as well as measurement of transcriptional activity of CTNNB1 (β-catenin) and HIF1A (HIF1-α) genes were prospectively studied in 60 endometriosis patients and 50 control group patients. The retrospective histopathological analysis was performed in 19 endometriosis associated ovarian cancer patients and 60 patients with histologically confirmed endometriosis.

RESULTS

Five endometriosis patients showed a deviation from normal cytogenetics finding without affecting of their phenotype. In 6 cases of endometriosis associated ovarian cancer ectopic endometrium was not confirmed. The remaining 13 cases demonstrated either benign or atypical endometriosis or even structures of borderline carcinoma. Atypical endometriosis was histologically confirmed in 20% of 60 endometriosis patients. Determination of gene expression (CTNNB1, HIF1A) formed two subgroups. Transcriptionally incipient endometriosis subgroup with insignificant genes expression compared to control group. In transcriptionally evident endometriosis subgroup were genes expressions significantly higher compared to control group (p < 0.01) as well as transcriptionally incipient endometriosis subgroup (p < 0.05).

CONCLUSIONS

Significant structural abnormalities of chromosomes are not included in genetic rigging of endometriosis patients. Atypical endometriosis represents a histopathologically detectable intermediate of endometriosis progression. Determination of genes expression CTNNB1 and HIF1A helps to allocate risk patients with endometriosis where more precise management is needed.

Novel Insights on the Role of Nitric Oxide in the Ovary: A Review of the Literature

Nitric oxide (NO) is formed during the oxidation of L-arginine to L-citrulline by the action of multiple isoenzymes of NO synthase (NOS): neuronal NOS (nNOS), endotelial NOS (eNOS), and inducible NOS (iNOS). NO plays a relevant role in the vascular endothelium, in central and peripheral neurons, and in immunity and inflammatory systems. In addition, several authors showed a consistent contribution of NO to different aspects of the reproductive physiology. The aim of the present review is to analyse the published data on the role of NO within the ovary. It has been demonstrated that the multiple isoenzymes of NOS are expressed and localized in the ovary of different species. More to the point, a consistent role was ascribed to NO in the processes of steroidogenesis, folliculogenesis, and oocyte meiotic maturation in in vitro and in vivo studies using animal models. Unfortunately, there are few nitric oxide data for humans; there are preliminary data on the implication of nitric oxide for oocyte/embryo quality and in-vitro fertilization/embryo transfer (IVF/ET) parameters. NO plays a remarkable role in the ovary, but more investigation is needed, in particular in the context of human ovarian physiology.

MiR-210-3p protects endometriotic cells from oxidative stress-induced cell cycle arrest by targeting BARD1

Endometriosis is associated with benign but adversely developed cysts in the extrauterine environment. The oxidative imbalanced environment induces DNA damage and affects cell cycle progression of endometrial stromal cells (ESCs) and endometrial epithelial cells, but how endometriotic cells maintain proliferation in the presence of oxidative stress is not clear. Growing evidence has indicated that the ectopic hypoxic microenvironment and oxidative stress can stimulate the growth of endometriotic cells, which is mainly due to the increase of HIF-1α. We found that the master hypoxia-associated miRNA miR-210-3p was increased in stromal and glandular cells of ectopic lesions compared with that of eutopic and normal endometria and was consistent with the expression of HIF-1α and the local oxidative stress-induced DNA damage predictor 8-OHdG. Moreover, miR-210-3p was upregulated in ESCs and Ishikawa cells under hypoxic conditions but not in normoxic culture. Knockdown of miR-210-3p induced a G2/M arrest of ESCs and Ishikawa cells under hypoxia, while no effect was found under normoxia. BARD1 was identified as a target of miR-210-3p. BARD1 expression was decreased in endometriotic tissues compared with eutopic and normal endometria and negatively correlated with the expression of miR-210-3p. Multivariate regression analysis showed that BARD1 downregulation could serve as an indicator for endometriotic severity. Our results suggest that miR-210-3p attenuates the G2/M cell cycle checkpoint by inactivating BRCA1 complex function in response to DNA damage under hypoxia via targeting the 3′ untranslated region of BARD1 mRNA. Endometriotic mouse model experiments showed that intraperitoneal injection of the miR-210-3p inhibitor or vitamin C suppressed the growth of endometriotic lesions. Together, our results demonstrate that endometriotic cells inhibit BARD1/BRCA1 function by upregulating miR-210-3p, which might be the underlying mechanism for endometriotic cell maintenance of growth in oxidative stress. Furthermore, inhibition of miR-210-3p and administration of vitamin C are promising approaches for the treatment of endometriosis.

Basic mechanisms of vascularization in endometriosis and their clinical implications

BACKGROUND

Vascularization is a major hallmark in the pathogenesis of endometriosis. An increasing number of studies suggests that multiple mechanisms contribute to the vascularization of endometriotic lesions, including angiogenesis, vasculogenesis and inosculation.

OBJECTIVE AND RATIONALE

In this review, we provide an overview of the basic mechanisms of vascularization in endometriosis and give special emphasis on their future clinical implications in the diagnosis and therapy of the disease.

SEARCH METHODS

Literature searches were performed in PubMed for English articles with the key words 'endometriosis', 'endometriotic lesions', 'angiogenesis', 'vascularization', 'vasculogenesis', 'endothelial progenitor cells' and 'inosculation'. The searches included both animal and human studies. No restriction was set for the publication date.

OUTCOMES

The engraftment of endometriotic lesions is typically associated with angiogenesis, i.e. the formation of new blood vessels from pre-existing ones. This angiogenic process underlies the complex regulation by angiogenic growth factors and hormones, which activate intracellular pathways and associated signaling molecules. In addition, circulating endothelial progenitor cells (EPCs) are mobilized from the bone marrow and recruited into endometriotic lesions, where they are incorporated into the endothelium of newly developing microvessels, referred to as vasculogenesis. Finally, preformed microvessels in shed endometrial fragments inosculate with the surrounding host microvasculature, resulting in a rapid blood supply to the ectopic tissue. These vascularization modes offer different possibilities for the establishment of novel diagnostic and therapeutic approaches. Angiogenic growth factors and EPCs may serve as biomarkers for the diagnosis and classification of endometriosis. Blood vessel formation and mature microvessels in endometriotic lesions may be targeted by means of anti-angiogenic compounds and vascular-disrupting agents.

WIDER IMPLICATIONS

The establishment of vascularization-based approaches in the management of endometriosis still represents a major challenge. For diagnostic purposes, reliable angiogenic and vasculogenic biomarker panels exhibiting a high sensitivity and specificity must be identified. For therapeutic purposes, novel compounds selectively targeting the vascularization of endometriotic lesions without inducing severe side effects are required. Recent progress in the field of endometriosis research indicates that these goals may be achieved in the near future.

Elevated Serum CD95/FAS and HIF-1α Levels, but Not Tie-2 Levels, May Be Biomarkers in Patients With Severe Endometriosis: A Preliminary Report

STUDY OBJECTIVE

To evaluate serum values of cluster of differentiation 95 (CD95/FAS), hypoxia-inducible factor 1-alpha (HIF-1α), and tyrosine kinase receptor 2 (Tie-2) as possible biomarkers of disease presence and severity in women with endometriosis, and to characterize the changes in these values in women with stage I/II and stage III/IV endometriosis.

DESIGN

Prospective study (Canadian Task Force classification I).

SETTING

University hospital.

PATIENTS

Thirty women with endometriosis and 30 healthy women without endometriosis.

INTERVENTION

For the diagnosis of endometriosis and prediction of its severity, we measured the serum levels of CD95/FAS, which assess apoptotic conditions, and of HIF-1α and Tie-2, which assess angiogenesis. Endometriosis was diagnosed and staged through surgical laparoscopy and later confirmed histologically. During the surgery, the patients with endometriosis were divided into 2 groups based on disease stage. Eleven patients had stage I/II endometriosis, and 19 had stage III/IV endometriosis.

MEASUREMENTS AND MAIN RESULTS

Endometriosis was associated with increased serum CD95/FAS and HIF-1α levels, but not Tie-2 levels. We also determined that stage III/IV endometriosis was associated with higher serum CD95/FAS and HIF-1α levels, but not Tie-2 levels, compared with stage I/II endometriosis.

CONCLUSION

Endometriosis, in accordance with its severity, increases serum CD95/FAS and HIF-1α levels, but not Tie-2 levels. These biomarkers may be useful for reproductive surgeons to improve the quality of counseling women about the presence and severity of endometriosis.

Effects of the hypoxia-inducible factor-1 inhibitor echinomycin on vascular endothelial growth factor production and apoptosis in human ectopic endometriotic stromal cells

Recent evidence points to a possible role for hypoxia-inducible factor (HIF)-1 in the pathogenesis and development of endometriosis. The objectives of this study were to investigate the critical role of HIF-1 in endometriosis and the effect of the HIF-1 inhibitor echinomycin on human ectopic endometriotic stromal cells (eESCs). Ectopic endometriotic tissues were obtained from 20 patients, who received an operation for ovarian endometriomas. We examined vascular endothelial growth factor (VEGF) and stromal cell-derived factor-1 (SDF-1) production, HIF-1 expression, cell proliferation and apoptosis of eESCs. Cobalt chloride (CoCl2) significantly induced expression of HIF-1α protein and VEGF production in a time-dependent manner in eESCs, but reduced SDF-1 production. VEGF production was significantly suppressed by treatment of 100 nM echinomycin without causing cell toxicity, but 0.1-10 nM echinomycin or 100 nM progestin had no significant effect. SDF-1 production was not affected by echinomycin treatment at any dose. Echinomycin inhibited cell proliferation and induced apoptotic cell death of the eESCs, and significantly inhibited expression of the anti-apoptotic proteins Bcl-2 and Bcl-xL. Echinomycin inhibits VEGF production and induces apoptosis of eESCs by suppression of Bcl-2 and Bcl-xL. These findings suggest the unique therapeutic potential for echinomycin as an inhibitor of HIF-1 activation for endometriosis treatment.

Endometriosis and ovarian cancer: potential benefits and harms of screening and risk-reducing surgery

Although endometriosis is well recognized as a benign gynecologic condition, its association with ovarian cancer (OVCA) has frequently been reported. Review articles on this topic are voluminous, yet there seems to be no consensus as to whether endometriosis is truly a precursor of OVCA and whether any screening or risk-reducing surgery should be instituted, on the basis of our current knowledge. In this review, published data are compiled and critically appraised. Through this critical appraisal, it seems clear that the strongest evidence seems to come from prevalence data. This type of data also suggests a reduced risk of certain histotypes (mainly type II) of OVCA in women with endometriosis. This may explain the rather moderate increase in risk as shown in epidemiologic studies. Even with this moderate increase in OVCA risk, caution should be exercised because of apparent bias in favor of publication of positive results, extensive heterogeneities among prevalence estimates, and inverse relationship between estimates and sizes of the studies. Many molecular studies are conflicting, and earlier studies showing molecular aberrations involved in genomic instability and mutation that enable malignant transformation are not replicated in later studies. Given the low incidence of OVCA and the rather moderate increase in risk of mostly type I tumors, screening seems to be ill-advised, and risk-reducing surgery such as salpingectomy with or without oophorectomy does not seem to yield any substantial benefit to women with endometriosis.

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.

Aberrant expression of the mammalian target of rapamycin, hypoxia-inducible factor-1α, and glucose transporter 1 in the development of ovarian clear-cell adenocarcinoma

Ovarian clear-cell adenocarcinoma (CCA) is known to be a type of cancer in humans with a high frequency of expression of the mammalian target of rapamycin (mTOR), hypoxia-inducible factor-1 (HIF-1), and glucose transporter 1 (Glut1). In this study, we aimed to determine how these alterations contribute to tumor development of CCAs. Immunohistochemical expressions of phosphorylated-mTOR (p-mTOR), HIF-1α, and Glut1 were analyzed in 36 CCAs and 60 coexistent putative precursor lesions: 19 nonatypical and 16 atypical endometriotic lesions, and 11 benign and 14 borderline clear-cell adenofibroma (CCAF) components. Twenty-one cases with solitary endometriosis were also examined. The frequencies of immunopositivity for p-mTOR (in cytoplasm or nucleus), HIF-1α (in nucleus), and Glut1 increased in accordance with higher cytological atypia in the putative precursors: 58%, 5%, and 16% in the nonatypical endometriosis; 63%, 37%, and 50% in the atypical endometriosis; 77%, 95%, and 95% in the endometriosis-associated CCAs; 27%, 0%, and 0% in the benign-CCAF components; 64%, 79%, and 43% in the borderline CCAF components; and 71%, 100%, and 93% in the CCAF-associated CCAs, respectively. p-mTOR, HIF-1α (in the nucleus), and Glut1 were positive in 10%, 5%, and 19% of the solitary endometriosis, respectively. In the putative precursor lesions coexisting with CCA, a strong correlation in the expression between p-mTOR and HIF-1α and between HIF-1α and Glut1 was identified. Expressions of p-mTOR, HIF-1α, and Glut1 have already been evident in the putative precursor lesions of CCA, and these alterations cumulatively occur in the development of ovarian CCA.

The proliferation, apoptosis, invasion of endothelial-like epithelial ovarian cancer cells induced by hypoxia

BACKGROUND

Epithelial ovarian cancer is one of the most malignant cancers in women because metastasis occurs in the most of patients by the time of diagnosis. Cancer cells have strong capacity to form angiogenesis or vasculogenic mimicry, which plays the major role in its malignant phenotype. Vasculogenic mimicry might contribute to the failure of the angiogenesis-targeted therapy strategies. Under the microenvironment of the tumor, hypoxia is the most common phenomena because of the vast energy and oxygen consuming. In the present study, the endothelial-like cells induced by hypoxia from SKOV-3 and ES-2 ovarian cancer cells were harvested to investigate the changes in their biological behaviors.

METHODS

The endothelial-like cells from SKOV-3 and ES-2 cells were harvested by laser capture microdissection. The biological behaviors of the endothelial-like cells, including proliferation, cell cycle, apoptosis, invasion and telomerase activity were determined by MTT, FCM, Transwell chamber and TRAP-ELISA methods. HIF-1α is the most important factor for the behavior changes under hypoxic condition. Some other genes relative to biological behaviors are also changes following the changes of HIF-1α. In order to elucidate the underlying mechanisms for these changes by hypoxia, the relative genes expressions including HIF-1α, CyclinD1, Flk-1, VEGF, p53 and V-src were determined by real-time PCR.

RESULTS

SKOV-3 and ES-2 cells were resistant to hypoxia by adoption of proliferation, apoptosis, differentiation and invasion. Combined with other studies, the more poorly cancer cells differentiate, the more strongly cells are resistant to hypoxia, the more possible to form vasculogenic mimicry. The changes in the expression of HIF-1α, and HIF-1α-dependent VEGF, Flk-1, Cyclin D1, and HIF-1α-independent p53 have been involved in this process.

CONCLUSIONS

HIF-1α took an important role in the behavioral changes of SKOV-3 and ES-2 cells by hypoxia. At the same time, other mechanisms were also involved in this process.