A role for prostacyclin (PGi2) in excessive menstrual bleeding

COVID-19 and abnormal uterine bleeding: potential associations and mechanisms

The impact of COVID-19 on menstruation has received a high level of public and media interest. Despite this, uncertainty exists about the advice that women and people who menstruate should receive in relation to the expected impact of SARS-CoV-2 infection, long COVID or COVID-19 vaccination on menstruation. Furthermore, the mechanisms leading to these reported menstrual changes are poorly understood. This review evaluates the published literature on COVID-19 and its impact on menstrual bleeding, discussing the strengths and limitations of these studies. We present evidence consistent with SARS-CoV-2 infection and long COVID having an association with changes in menstrual bleeding parameters and that the impact of COVID vaccination on menstruation appears less significant. An overview of menstrual physiology and known causes of abnormal uterine bleeding (AUB) is provided before discussing potential mechanisms which may underpin the menstrual disturbance reported with COVID-19, highlighting areas for future scientific study. Finally, consideration is given to the effect that menstruation may have on COVID-19, including the impact of the ovarian sex hormones on acute COVID-19 severity and susceptibility and reported variation in long COVID symptoms across the menstrual cycle. Understanding the current evidence and addressing gaps in our knowledge in this area are essential to inform public health policy, direct the treatment of menstrual disturbance and facilitate development of new therapies, which may reduce the severity of COVID-19 and improve quality of life for those experiencing long COVID.

Understanding the cross-talk between mediators of infertility and COVID-19

COVID-19 is the ongoing health emergency affecting individuals of all ages around the globe. Initially, the infection was reported to affect pulmonary structures. However, recent studies have delineated the impacts of COVID-19 on the reproductive system of both men and women. Hence, the present review aims to shed light on the distribution of SARS-CoV-2 entry factors in various reproductive organs. In addition, impacts of COVID-19 mediators like disrupted renin angiotensin system, oxidative stress, cytokine storm, fever, and the mental stress on reproductive physiology have also been discussed. For the present study, various keywords were used to search literature on PubMed, ScienceDirect, and Google Scholar databases. Articles were screened for relevancy and were studied in detail for qualitative synthesis of the review. Through our literature review, we found a multitude of effects of COVID-19 mediators on reproductive systems. Studies reported expression of receptors like ACE-2, TMPRSS2, and CD147 in the testes, epididymis, prostrate, seminal vesicles, and ovarian follicles. These proteins are known to serve as major SARS-CoV-2 entry factors. The expression of lysosomal cathepsins (CTSB/CTSL) and/ neuropilin-1 (NRP-1) are also evident in the testes, epididymis, seminal vesicles, fallopian tube, cervix, and endometrium. The binding of viral spike protein with ACE-2 was found to alter the renin-angiotensin cascade, which could invite additional infertility problems. Furthermore, COVID-19 mediated cytokine storm, oxidative stress, and elevated body temperature could be detrimental to gametogenesis, steroidogenesis, and reproductive cycles in patients. Finally, social isolation, confinement, and job insecurities have fueled mental stress and frustration that might promote glucocorticoid-mediated subnormal sperm quality in men and higher risk of miscarriage in women. Hence, the influence of COVID-19 on the alteration of reproductive health and fertility is quite apparent.

Hemodynamic forces enhance decidualization via endothelial-derived prostaglandin E2 and prostacyclin in a microfluidic model of the human endometrium

STUDY QUESTION

Does the uterine vasculature play a localized role in promoting stromal cell decidualization in the human endometrium?

SUMMARY ANSWER

Our study demonstrated that hemodynamic forces induced secretion of specific endothelial cell-derived prostanoids that enhanced endometrial perivascular decidualization via a paracrine mechanism.

WHAT IS KNOWN ALREADY

Differentiation of stromal cell fibroblasts into the specialized decidua of the placenta is a progesterone-dependent process; however, histologically, it has long been noted that the first morphological signs of decidualization appear in the perivascular stroma. These observations suggest that the human endometrial vasculature plays an active role in promoting stromal differentiation.

STUDY DESIGN, SIZE, DURATION

Primary human endometrial stromal cells were co-cultured for 14 days with primary uterine microvascular endothelial cells within a microfluidic Organ-on-Chip model of the endometrium.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Cultures were maintained with estradiol and a progestin, with or without continuous laminar perfusion to mimic hemodynamic forces derived from the blood flow. Some cultures additionally received exogenous agonist-mediated challenges. Decidualization in the microfluidic model was assessed morphologically and biochemically. ELISA was used to examine the culture effluent for expression of decidualization markers and prostaglandins. Immunofluorescence was used to monitor cyclooxygenase-2 expression in association with decidualization.

MAIN RESULTS AND THE ROLE OF CHANCE

A significantly enhanced stromal decidualization response was observed in the co-cultures when the endothelial cells were stimulated with hemodynamic forces (e.g. laminar shear stress) derived from controlled microfluidic perfusion (<0.001). Furthermore, the enhanced progestin-driven stromal differentiation was mediated via cyclooxygenase-2 and the paracrine action of prostaglandin E2 and prostacyclin. Altogether, these translational findings indicate that the vascular endothelium plays a key physiologic role during the early events of perivascular decidualization in the human endometrium.

LARGE SCALE DATA

N/A.

LIMITATIONS, REASONS FOR CAUTION

This report is largely an in vitro study. Although we were able to experimentally mimic hemodynamic forces in our microfluidic model, we have not yet determined the contribution of additional cell types to the decidualization process or determined the precise physiological rates of shear stress that the microvasculature of the endometrium undergoes in vivo.

WIDER IMPLICATIONS OF THE FINDINGS

Identification of specific endothelial-derived prostaglandins and their role during endometrial reproductive processes may have clinical utility as therapeutic targets for reproductive disorders such as infertility, endometriosis, adenomyosis, pre-eclampsia and poor pregnancy outcomes.

STUDY FUNDING/COMPETING INTEREST(S)

This work was supported by the Veterans Affairs (I01 BX002853), the Bill and Melinda Gates Foundation Grand Challenges Exploration (OPP1159411), the Environmental Toxicology Training Grant (NIH T32 ES007028) and the Environmental Protection Agency STAR Center Grant (83573601).

CONFLICT OF INTEREST

The authors report no conflicts of interest.

TRIAL REGISTRATION NUMBER

N/A.

Gynaecology problems in puberty

With the onset of puberty a range of problems may be encountered by the young girl. Some of these include a range of gynaecological issues relating to delayed onset of puberty, delayed menarche, atypical pubertal changes and the identification of anomalies of the genital tract. The distinction between physiological events and pathological problems is important to avoid unnecessary distress and anxiety. The onset of cyclic hormonal changes also provokes a number of "non-gynaecological" problems - where the link to cyclic hormonal events is often overlooked and an important opportunity to potentially intervene and assist is missed. From a global perspective there are a range of problems that are particularly encountered with the onset of puberty including the risks of sexual violence, which in the setting of having achieved the age of reproductive potential result in unplanned pregnancies, unsafe abortions and adolescent pregnancy all of which pose life threatening risks. Sex education in its broadest sense is important for all young people. Access to contraception for adolescents is vital, such that clinicians across all streams of health care who are involved in the care of young people should take the opportunity to educate and provide this care.

The significance and evolution of menstruation

Historically, the evolutionary origins of menstruation have been based on two theories: the ability to eliminate infectious agents carried to the uterus with spermatozoa and the comparative conservation of energy with menstruation compared to its absence. In the menstruating species, more recent theories have identified spontaneous decidualization as the key adaptive mechanism. Spontaneous decidualization is seen as a mechanism to provide the mother with protection from the invasive characteristics of the embryo. Physiologically, menstruation involves complex interactions of inflammation and vascular mechanisms to stabilize the endometrium and allow a regulated loss of endometrial tissues and blood. A variety of human illnesses can be better understood as vulnerabilities associated with these evolutionary developments, including recurrent pregnancy loss, placenta accreta, ectopic pregnancy, endometriosis, adenomyosis, dysmenorrhea, and chronic pelvic pain. While the evolutionary aspects of these diseases indicate why such illnesses can occur, in some instances, they also provide a basis for treatment, prevention and future research direction.

Abnormal Uterine Bleeding: Current Classification and Clinical Management

Abnormal uterine bleeding is now classified and categorized according to the International Federation of Gynecology and Obstetrics classification system: PALM-COEIN. This applies to nongravid women during their reproductive years and allows more clear designation of causes, thus aiding clinical care and future research.

Efficacy of Foley's Catheter and the Effect of Histopathology, Age and Endometrial Thickness Relative to the Measured Outcomes in Menorrhagia

INTRODUCTION

Menorrhagia adversely affects the quality of life. Hysterectomy is the definitive treatment for menorrhagia however, a number of conservative alternatives are available.

AIM

Hysterectomy is the definitive treatment for menorrhagia however, a number of conservative alternatives are available. A thermal balloon is an effective but costly option. We used a Foley's catheter as an alternative to commercially available thermal balloons. If effective, it will provide a cheap alternative to the thermal balloon.

MATERIALS AND METHODS

A Foley's catheter was placed in the uterine cavity for 10 minutes using 0.9% saline. The measured outcomes were amenorrhea, eumenorrhea, oligomenorrhea or failure of the therapy. Endometrial thickness, age and endometrial biopsy results were also measured to determine if these variables had any effects on the outcome.

RESULTS

Out of the total 42 participants, nearly half had amenorrhea (42.9%, n=18). Furthermore, 28.6% had oligomenorrhea (n=12) and 26.2% experienced eumenorrhea (n=11). Only one participant failed to respond (2.4%, n=1). There were no differences in outcomes between the different forms of histopathology. This means that thermal balloon therapy is effective in causing amenorrhea. No significant relationships existed between participants' measured outcomes and a model containing predictor variables (age and endometrial thickness), R=0.313, R2=0.098, p=0.141.

CONCLUSION

A Foley's catheter is effective with reasonable measured outcomes in cases of menorrhagia.

Menstrual physiology: implications for endometrial pathology and beyond

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Recent advances in managing and understanding menstrual disorders

Menstrual disorders are a major reason for gynaecological consultations worldwide and, unfortunately there are many different definitions and classifications of this condition. Clear definitions and terminology are necessary for scientific literature, particularly for clinicians, and for clinical trials comparing two treatments. The International Federation of Gynaecology and Obstetrics (FIGO) Menstrual Disorders Working Group has proposed abandoning the use of one common term, dysfunctional uterine bleeding (DUB), while continuing to use the terms abnormal uterine bleeding (AUB) and heavy menstrual bleeding (HMB). Furthermore, the group issued the PALM-COEIN classification system for menstrual disorders, which has quickly been adopted around the world. The PALM-COEIN system allows clinicians and researchers to identify and classify women with both AUB and HMB in a systematic manner, provides reliable information for research purposes and for epidemiological and prevalence studies in different settings, and supports accurate diagnoses and treatment. Additionally, this classification system is useful for selecting treatments appropriate for different stages of women's reproductive years and for different patterns of menstrual bleeding. Among the proposed treatments are the use of combined oral contraceptives, the levonorgestrel-releasing intrauterine system, tranexamic acid, mefenamic acid, and other nonsteroidal anti-inflammatory drugs (NSAIDs).

Diagnosis and Management of Formerly Called "Dysfunctional Uterine Bleeding" According to PALM-COEIN FIGO Classification and the New Guidelines

In 2011, the FIGO classification system (PALM-COEIN) was published to standardize terminology, diagnostic and investigations of causes of abnormal uterine bleeding (AUB). According to FIGO new classification, in the absence of structural etiology, the formerly called "dysfunctional uterine bleeding" should be avoided and clinicians should state if AUB are caused by coagulation disorders (AUB-C), ovulation disorder (AUB-O), or endometrial primary dysfunction (AUB-E). Since this publication, some societies have released or revised their guidelines for the diagnosis and the management of the formerly called "dysfunctional uterine bleeding" according new FIGO classification. In this review, we summarize the most relevant new guidelines for the diagnosis and the management of AUB-C, AUB-O, and AUB-E.

Classification of menstrual bleeding disorders

There exists a spectrum of potential causes of abnormal uterine bleeding (AUB) in nonpregnant reproductive-aged women. In some instances the abnormal bleeding may emanate from definable pathologic entities in the endometrial cavity such as polyps or submucous leiomyomas (fibroids), while in others, it may occur secondary to coagulopathies or disorders of local or systemic hemostasis. If the patient is subjected to a rigorous evaluation more than one potential contributor may be identified, a circumstance that challenges the clinician since entities such as polyps, leiomyomas, and adenomyosis may frequently be asymptomatic, even in women with AUB. The bench or clinical investigator may also be influenced by the existence of the multiplicity of potential causes that could confound the results of research. This paper describes FIGO's (Fédération Internationale de Gynécologie et d'Obstétrique) new PALM-COEIN classification of causes of AUB in the reproductive years (Polyp, Adenomyosis, Leiomyoma, Malignancy and hyperplasia-Coagulopathy, Ovulatory disorder, Endometrial, Iatrogenic, Not yet classified). This system is designed to assist clinicians in the evaluation of patients, investigators in the design and interpretation of research and faculty in the education of medical students and residents/trainees. Additionally, given the longstanding existence of a confusing array of conflicting definitions, the manuscript describes the FIGO standardized terminology for both normal menstruation and AUB symptoms.

The FIGO systems for nomenclature and classification of causes of abnormal uterine bleeding in the reproductive years: who needs them?

In November 2010, the International Federation of Gynecology and Obstetrics formally accepted a new classification system for causes of abnormal uterine bleeding in the reproductive years. The system, based on the acronym PALM-COEIN (polyps, adenomyosis, leiomyoma, malignancy and hyperplasia-coagulopathy, ovulatory disorders, endometrial causes, iatrogenic, not classified) was developed in response to concerns about the design and interpretation of basic science and clinical investigation that relates to the problem of abnormal uterine bleeding. A system of nomenclature for the description of normal uterine bleeding and the various symptoms that comprise abnormal bleeding has also been included. This article describes the rationale, the structured methods that involved stakeholders worldwide, and the suggested use of the International Federation of Gynecology and Obstetrics system for research, education, and clinical care. Investigators in the field are encouraged to use the system in the design of their abnormal uterine bleeding-related research because it is an approach that should improve our understanding and management of this often perplexing clinical condition.

Oral Modified-Release Tranexamic Acid for Heavy Menstrual Bleeding

OBJECTIVE:

To review the pharmacology, pharmacokinetics, efficacy, and safety profile of an oral modified-release (MR) formulation of tranexamic acid.

DATA SOURCES:

Literature was accessed through MEDLINE (1966-July 2012), Iowa Drug Information Service (1997-July 2012), and bibliographies of pertinent articles. Search terms included tranexamic acid, Lysteda, menorrhagia, menstrual blood loss, and heavy menstrual bleeding.

STUDY SELECTION AND DATA EXTRACTION:

All available English-language abstracts and human studies were identified for review. Data provided by the manufacturer and the Food and Drug Administration were also evaluated. Efficacy was evaluated in 2 clinical trials, change in quality of life was evaluated in 3 clinical trials, and safety was evaluated in 4 clinical trials.

DATA SYNTHESIS:

Tranexamic acid is a synthetic lysine analogue with antifibrinolytic activity. It interferes with the binding of plasminogen to fibrin, resulting in enhanced fibrin clot integrity. A novel MR formulation of oral tranexamic acid is approved for treatment of cyclic heavy menstrual bleeding. MR tranexamic acid is initiated at the beginning of heavy menstrual bleeding and can be taken for up to 5 days per cycle. Clinical trials show it to be safe and effective. Dosage adjustments are needed for women with renal insufficiency. Adverse effects are considered mild to moderate, with the most common being menstrual discomfort, headache, and back pain. The most significant safety concerns relate to the risk of thromboembolism.

CONCLUSIONS:

MR tranexamic acid offers a new first-line therapy for patients with cyclic heavy menstrual bleeding. It is reported to be safe and effective. There are no labeled equivalents to MR tranexamic acid for cyclic heavy menstrual bleeding.

Progesterone: a pivotal hormone at menstruation

The human endometrium is exposed to repeated inflammation every month, culminating in tissue breakdown and menstruation. Subsequently, the endometrium has a remarkable capacity for efficient repair and remodeling to enable implantation if fertilization takes place. Endometrial function is known to be governed by the ovarian hormones estradiol and progesterone. This review paper focuses on hormonal control of the cyclical tissue injury and repair that takes place in the local endometrial environment at the time of menstruation. Progesterone levels decline premenstrually as the corpus luteum regresses in the absence of pregnancy, and estradiol levels increase during the postmenstrual phase. The functional impact of these significant changes is discussed, including their immediate and downstream effects. Finally, we examine the contribution of aberrant endometrial function to the presentation of heavy menstrual bleeding and identify potential therapeutic targets for the treatment of this common gynecological problem.

The FIGO classification of causes of abnormal uterine bleeding in the reproductive years

At this juncture, clinical management, education for medical providers, and the design and interpretation of clinical trials have been hampered by the absence of a consensus system for nomenclature for the description of symptoms as well as classification of causes or potential causes of abnormal uterine bleeding (AUB). To address this issue, the Fédération Internationale de Gynécologie et d'Obstétrique (FIGO) has designed the PALM-COEIN (Polyp, Adenomyosis, Leiomyoma, Malignancy and Hyperplasia, Coagulopathy, Ovulatory Disorders, Endometrial Disorders, Iatrogenic Causes, and Not Classified) classification system for causes of AUB in the reproductive years.

FIGO classification system (PALM-COEIN) for causes of abnormal uterine bleeding in nongravid women of reproductive age

There is general inconsistency in the nomenclature used to describe abnormal uterine bleeding (AUB), in addition to a plethora of potential causes-several of which may coexist in a given individual. It seems clear that the development of consistent and universally accepted nomenclature is a step toward rectifying this unsatisfactory circumstance. Another requirement is the development of a classification system, on several levels, for the causes of AUB, which can be used by clinicians, investigators, and even patients to facilitate communication, clinical care, and research. This manuscript describes an ongoing process designed to achieve these goals, and presents for consideration the PALM-COEIN (polyp; adenomyosis; leiomyoma; malignancy and hyperplasia; coagulopathy; ovulatory dysfunction; endometrial; iatrogenic; and not yet classified) classification system for AUB, which has been approved by the International Federation of Gynecology and Obstetrics (FIGO) Executive Board as a FIGO classification system.

Altered responsiveness of small uterine arteries in women with idiopathic menorrhagia

OBJECTIVE

This study was undertaken to study vascular reactivity of small myometrial arteries in women with idiopathic menorrhagia.

STUDY DESIGN

Small myometrial arteries were isolated from 6 patients with idiopathic menorrhagia and 4 controls. The contractile responses to thromboxane mimetic (U46619) and endothelin-1 were assessed before and after incubation with N(w)-nitro-L arginine methyl ester alone or in combination with indomethacin (Indo). Endothelium-dependent dilation to bradykinin and basal tension were compared before and after incubation with N(w)-nitro-L arginine methyl ester alone, or with N(w)-nitro-L arginine methyl ester in combination with indomethacin.

RESULTS

Constriction to endothelin-1 was enhanced in idiopathic menorrhagia arteries (P < .05). Idiopathic menorrhagia arteries demonstrated enhanced basal tension after incubation with N(w)-nitro-L arginine methyl ester, which was further exaggerated by indomethacin. NOS inhibition had no effect on basal tension in controls, but basal tension was enhanced after inhibition of cyclooxygenase-derived products (P < .05). Bradykinin-mediated dilation was significantly increased in idiopathic menorrhagia (P < .05).

CONCLUSION

The presence of functional alterations in small myometrial arteries could contribute to idiopathic menorrhagia.

Reduced levels of VEGF-A and MMP-2 and MMP-9 activity and increased TNF-alpha in menstrual endometrium and effluent in women with menorrhagia

BACKGROUND

Heavy regular menstrual periods (menorrhagia) are an important cause of ill health in women and remain the leading indication for hysterectomy. Abnormalities of the endometrial blood vessels are among the possible causes of this condition. Many different factors affect endothelial cell growth, function and vessel remodelling. We sought to determine whether the levels of vascular endothelial growth factor-A (VEGF-A), tumour necrosis factor-alpha (TNF-alpha), matrix metalloproteinase (MMP)-2 and MMP-9 and soluble VEGF receptor-1 (VEGF-R1) were altered in the menstrual effluent of women with objective menorrhagia. We have also quantitated the VEGF-A mRNA in the menstruated endometrium.

METHODS AND RESULTS

We recruited 37 women and determined their menstrual blood loss (MBL) over two cycles and collected menstrual effluent during the 2nd day of bleeding for 4 h. There was no difference in the total level of VEGF-A, and neither latent MMP. However, the concentration of VEGF-A was significantly reduced in the women with menorrhagia, as was the VEGF-A mRNA level. In addition, the active forms of both MMPs were markedly reduced and the total sVEGF-R1 as well as the TNF-alpha content were increased.

CONCLUSIONS

This is the first study to show abnormalities of factors important for endothelial cell behaviour in the endometrium of women with menorrhagia. This may underlie the disordered vessel structure and/or function in this condition.

Endocrine regulation of menstruation

In women, endometrial morphology and function undergo characteristic changes every menstrual cycle. These changes are crucial for perpetuation of the species and are orchestrated to prepare the endometrium for implantation of a conceptus. In the absence of pregnancy, the human endometrium is sloughed off at menstruation over a period of a few days. Tissue repair, growth, angiogenesis, differentiation, and receptivity ensue to prepare the endometrium for implantation in the next cycle. Ovarian sex steroids through interaction with different cognate nuclear receptors regulate the expression of a cascade of local factors within the endometrium that act in an autocrine/paracrine and even intracrine manner. Such interactions initiate complex events within the endometrium that are crucial for implantation and, in the absence thereof, normal menstruation. A clearer understanding of regulation of normal endometrial function will provide an insight into causes of menstrual dysfunction such as menorrhagia (heavy menstrual bleeding) and dysmenorrhea (painful periods). The molecular pathways that precipitate these pathologies remain largely undefined. Future research efforts to provide greater insight into these pathways will lead to the development of novel drugs that would target identified aberrations in expression and/or of local uterine factors that are crucial for normal endometrial function.

Abnormal uterine bleeding and underlying hemostatic disorders: report of a consensus process

An ad hoc consensus group determined that the prevalence of von Willebrand's disease in females with heavy menstrual bleeding is approximately 13%, but the severity of the disorder varies and, consequently, the overall clinical impact remains unknown. Consensus recommendations are presented, which include [1] a structured history for screening females with heavy menstrual bleeding; [2] a collaborative, multidisciplinary evaluation, and [3] a strategy for future basic science and clinical investigation.

Requirements for research investigations to clarify the relationships and management of menstrual abnormalities in women with hemostatic disorders

This article highlights a comprehensive range of research investigations which are required to clarify the relationships between the symptom of excessively heavy menstrual bleeding and different disorders of systemic hemostasis and their management. The need for these investigations was stimulated by an international workshop involving hematologists and gynecologists with expertise and interests in these fields. The field was reviewed by a group of experts who systematically considered nomenclature, definitions, investigations, and management and identified areas of uncertainty, controversy, or absence of information. This article is an extension of those preliminary research discussions. Recommendations are made for a range of important research studies to define the nomenclature, definitions, mechanisms, clinical investigations and management of heavy menstrual bleeding in women with disorders of systemic hemostasis.

Temporal expression and signalling of prostacyclin receptor in the human endometrium across the menstrual cycle

Prostacyclin (PGI(2)) synthesis and function in the human uterus has been implicated in the regulation of the process of normal and dysfunctional menstruation. PGI(2) synthesis is elevated during normal menstruation and is also associated with blood loss in women who suffer from heavy menses. This study was designed to outline further the role of PGI(2) in menstruation by investigating the temporal pattern and site of expression of prostaglandin I synthase (PGIS) and the prostacyclin receptor (IP receptor) in the non-pregnant human endometrium across the menstrual cycle. Quantitative RT-PCR demonstrated increased expression of PGIS and IP receptor during the menstrual phase of the cycle compared with all other phases (P < 0.05). Furthermore, PGIS and IP receptor were localised to the glandular epithelium, stromal and endothelial cells in the basal and functional layers of the endometrium. Functionality of the IP receptor in the human endometrium was assessed by measuring cAMP generation following treatment with 100 nmol l(-1) of the PGI(2) analogue, iloprost. cAMP generation was significantly higher in endometrial tissue collected during the proliferative compared with the secretory phase of the menstrual cycle (P < 0.05). In conclusion, this study has confirmed increased expression and signalling of PGIS and IP receptor during the menstrual phase and outlines a potential autocrine/paracrine role for PGI(2) on several cellular compartments in the endometrium including the endothelium. This may underscore a pivotal role for PGI(2) receptor signalling in normal and dysfunctional menstruation.

Cyclooxygenase enzymes and prostaglandins in reproductive tract physiology and pathology

Prostaglandins, thromboxanes (TX) and leukotrienes, collectively referred to as eicosanoids, are cyclooxygenase (COX) metabolites of arachidonic acid (AA). Prostaglandins, have been recognised for many years as key molecules in regulating reproductive tract physiology and pathology. Numerous recent studies in in vitro model systems and knockout mouse models have demonstrated specific functional roles for the respective cyclooxygenase enzymes, prostaglandins and prostanoid receptors. Here we review the findings obtained in several of these studies with emphasis on the roles played by cyclooxygenase enzymes and prostaglandins, specifically prostaglandin E2 (PGE2) and F2alpha in reproductive tract physiology and pathology.

Cyclooxygenase-2 overexpression inhibits cathepsin D-mediated cleavage of plasminogen to the potent antiangiogenic factor angiostatin

Overexpression of cyclooxygenase (COX)-2 and enhanced synthesis of prostaglandin E2 (PGE2) have been implicated in human endometrial pathologies. To investigate the molecular role of COX-2, the Ishikawa human endometrial epithelial cell line was stably transfected with the pIRES2 vector containing COX-2 cDNA in either the sense or antisense directions. PGE2 concentrations were significantly elevated in the cells transfected with the COX-2 sense compared with wild-type cells or cells transfected with the antisense cDNA (P < 0.01). Elevated PGE2 synthesis was associated with enhanced expression and signaling of PGE2 receptors (EP). cDNA array analysis revealed differential expression of cathepsin D between the COX-2 sense and antisense cells. Cathepsin D RNA and protein expression was 6.7- and 2.1-fold lower in the COX-2 sense compared with COX-2 antisense cells respectively. Cathepsin D is known to cleave plasminogen to the potent antiangiogenic factor angiostatin. To investigate differential angiostatin generation, conditioned media from COX-2 sense, COX-2 antisense and wild-type cells were incubated with plasminogen and subsequently subjected to Western blot analysis. In comparison to wild-type cells, the cleavage of plasminogen to angiostatin was abolished when incubated in COX-2 sense cells conditioned media and elevated when incubated in COX-2 antisense cells conditioned media. Coincubation of plasminogen with the cathepsin D inhibitor pepstatin A inhibited the cleavage of plasminogen to angiostatin in the COX-2 antisense conditioned media. These data demonstrate that COX-2 exerts a negative feedback on the expression of cathepsin D. This in turn reduces the generation of the antiangiogenic factor angiostatin, hence promoting a proangiogenic environment.

Cyclooxygenase enzymes and prostaglandins in pathology of the endometrium

Prostaglandins are bioactive lipids produced from arachidonic acid by cyclooxygenase (COX) enzymes and specific terminal prostanoid synthase enzymes. After biosynthesis, prostaglandins exert an autocrine-paracrine function by coupling to specific prostanoid G protein-coupled receptors to activate intracellular signalling and gene transcription. For many years, prostaglandins have been recognized as key molecules in reproductive biology by regulating ovulation, endometrial physiology and proliferation of endometrial glands and menstruation. More recently, a role for COX enzymes and prostaglandins has been ascertained in reproductive tract pathology, including carcinomas, menorrhagia, dysmenorrhoea and endometriosis. Although the mechanism by which prostaglandins modulate these pathologies is still unclear, a large body of evidence supports a role for COX enzymes, prostaglandins and prostaglandin receptor signalling pathways in angiogenesis, apoptosis and proliferation, tissue invasion and metastases and immunosuppression. Here, an overview is provided of some of the findings from these studies with specific emphasis on the role of COX enzymes, prostaglandin E(2) and F(2alpha) in disorders of endometrial proliferation and menstruation in non-pregnant women.

Human uterine vascular structures in normal and diseased states

Menstrual bleeding disorders are one of the most common problems presenting to the gynaecologist. There is increasing evidence that alterations in human uterine vascular structures are associated with spontaneous and sex steroid-induced changes in menstrual bleeding patterns. This article will discuss the normal anatomy and physiology of uterine vascular growth, breakdown, and repair and will indicate where altered anatomy and function may contribute to menstrual disorder. In particular, impact of low-dose progestogens on the endometrial vasculature and endometrial vascular fragility will be discussed. Disturbances of myometrial vascular growth and remodeling, including fibroids, adenomyosis, implantation, and arterio-venous malformations will also be addressed.

Clinical implications of disturbances of uterine vascular morphology and function

Menstrual disturbances are one of the most common problems presenting to the gynaecologist. In order for the endometrium to bleed, vessels must break down. Disruption in the regulation of endometrial vascular growth and function has been found in association with spontaneous and sex steroid-induced disturbances of menstrual bleeding. Although circulating oestrogens and progestogens influence the endometrial vessels, this effect appears to be indirect, and regulation is primarily via local factors. Deficient vasoconstriction and haemostasis with excessive fibrinolysis is seen in menorrhagia. Breakthrough bleeding in users of progestogen-only contraceptives is associated with increased superficial vascular fragility and disruptions in the supporting basement membrane. Blood vessels in uterine fibroids are abnormal in distribution and appearance. Adenomyosis is also commonly associated with menstrual disturbance, and alterations in vascular distribution suggest altered angiogenesis. Successful human embryo implantation requires endometrial vascular breakdown. Excessive thrombosis associated with the antiphospholipid syndrome may interfere with this re-modelling and compromise implantation. Arteriovenous malformations are a rare but important cause of excessive or irregular vaginal bleeding. Abundant vessels with abnormal morphology, associated with aberrant angiogenesis can be seen, and embolization of these vessels may be an effective conservative treatment. Improved understanding of the regulation of the uterine vasculature is likely to lead to targeted therapies to prevent unscheduled vascular breakdown and to control menstrual disturbance at an endometrial level.

Medical management of abnormal uterine bleeding

Abnormal uterine bleeding occurs secondary to a wide variety of functional and structural abnormalities. Although there is clearly a place for surgery, medical therapy has enormous potential for most women, especially those with dysfunctional uterine bleeding. To provide women with appropriate options for therapy, the clinician must be prepared to distinguish abnormal bleeding that is associated with ovulation from that which is anovulatory and to use appropriate ancillary tests to identify structural and endocrinologic anomalies or lifestyle factors that may explain the bleeding. In undertaking such an investigation, it is important for the clinician to be able to distinguish lesions that may be asymptomatic and unrelated to the bleeding from those that truly are the source of the problem. With this information, a rationally determined set of medical and, if appropriate, surgical therapeutic options may be presented to the woman. Among these medical treatment options are a number of treatment options that have not seen widespread use in North America but are inexpensive, effective, and well tolerated. It is clear that medical therapy is not for everyone. Women deserve the opportunity to relieve their symptoms with nonsurgical options.

Tenoxicam versus lynestrenol-ethinyl estradiol treatment of dysfunctional uterine bleeding cases during adolescence

BACKGROUND

The purpose of this study was to compare the effectiveness of tenoxicam versus lynestrenol-ethinyl estradiol (L-EE) in the treatment of severe cases of dysfunctional uterine bleeding (DUB) during adolescence.

METHODS

Forty-eight patients with objective DUB completed a randomized comparative trial of treatment with tenoxicam (20 mg daily, n = 23) or L-EE (1 tablet containing 0.05 mg + 2.5 mg, respectively, 3 times daily, n = 25). Treatment was given during menorrhagia until bleeding ceased. Mean age of the patients was 13.74 +/- 2.1 years (range, 11-18 years).

RESULTS

A significantly higher level of hematocrit (35.9% v 32.6%, t = 2.1, P = 0.0217) and hemoglobin (11.5 v 10.4 g%, t = 1.7, P = 0.0495), and significantly less hospitalization (5.75 v 8.33 days, t = 2.45, P = 0.0106) was seen in the tenoxicam group in comparison to L-EE group after completion of the treatment. Three patients were submitted to curettage and seven to transfusion in the group receiving L-EE, but no patients in the tenoxicam group required these procedures.

CONCLUSIONS

Tenoxicam is considered an effective medication for the management of DUB during adolescence.

Dysfunctional uterine bleeding and dysmenorrhea

Normal menstruation involves the breakdown, remodelling and repair of the functional endometrial layers. Endometrial destruction and regeneration are largely controlled local factors, that are dependent on the levels of estradiol and progesterone. Prostaglandins and endothelins appear to be powerful vasoactive substances in the control of menstrual blood loss. The tissue endothelin concentration may interact with relaxing factors, such as nitric oxide, prolonging or increasing menstrual blood loss. Disturbances of menstrual bleeding and dysmenorrhea are a major medical problem not only for women but also for their families and health services. Management of dysfunctional uterine bleeding is determined by the needs of the patient: oral contraceptives are used for women of reproductive age with ovulatory uterine bleeding episodes who also require contraception; they have a strong progestogenic effect that is evident as early as the first week of pill intake. In the perimenopausal patient, dysfunctional uterine bleeding may be treated by cyclic progestins with or without conjugated equine estrogens; oral contraceptives can also be used in non-smokers who have no evidence of vascular disease. Dysmenorrhea is defined as a complaint of pain experienced during or immediately before menstruation. In the pathogenesis of dysmenorrhea, prostaglandins and arachinodonic acid metabolites play an important role, being elevated in women with dysmenorrhea. Oral contraceptives are very effective in the treatment of dysmenorrhea; they act mainly by reducing the levels of the prostaglandins and arachinodonic acid metabolites. For women reluctant to take oral contraceptives, non-steroidal anti-inflammatory drugs may be a better option.

The control of prostaglandin production by the endometrium in relation to luteolysis and menstruation

Oestradiol acting on a progesterone-primed uterus stimulates prostaglandin (PG) F2 alpha synthesis by the endometrium. In some species (notably the sheep, cow and goat) oxytocin released from the ovary also forms part of the physiological stimulus for increased endometrial PGF2 alpha production. The corpus luteum contains high concentrations (> 1 microgram/g tissue) of this peptide in these species. The intracellular mechanisms by which these three hormones control endometrial PGF2 alpha synthesis and release are far from clear. Oxytocin stimulates the synthesis of inositol phosphates and diacylglycerol in the endometrium of some species, but whether this pathway is involved in endometrial PGF2 alpha synthesis is still open to question. There is evidence that increased endometrial PGF2 alpha synthesis is dependent upon increased endometrial protein synthesis but, apart from the recorded effects of steroid hormones on the concentrations of phospholipase A2, prostaglandin H synthase and oxytocin receptors, it is not known what other endometrial proteins are involved. Some disorders of menstruation are associated with abnormal PG production by the endometrium, but the reasons for this abnormality are not clear. During early pregnancy an increase in PGF2 alpha synthesis by the endometrium is prevented, except in the pig where the PGF2 alpha produced is directed from the venous drainage to the uterine lumen. In those species in which endometrial PGF2 alpha synthesis is dependent upon oxytocin secreted by the ovary, the conceptus secretes an interferon-tau (previously named trophoblast protein-1) which prevents oestradiol and oxytocin acting on a progesterone-primed uterus from stimulating endometrial PGF2 alpha synthesis. The identities of the factors produced by the conceptus which prevent endometrial PGF2 alpha synthesis during early pregnancy in other species are not known, although it is clear that they are not interferons.

Prostaglandin synthesis inhibitors in menorrhagia, intrauterine contraceptive device-induced side effects and endometriosis

Primary menorrhagia, IUD side effects and endometriotic symptoms may be a result of excessive PG release in the reproductive organs. These conditions and symptoms can be prevented or markedly alleviated by a PG synthesis inhibitor, such as tolfenamic acid. This treatment, which is used only intermittently, has been well tolerated with no serious side effects.

The effect of caffeine on prostaglandin output from the guinea-pig uterus

1. Caffeine increased the outputs of prostaglandin F2 alpha (PGF2 alpha), PGE2 and 6-keto-PGF1 alpha from the guinea-pig uterus on days 7 and 15 of the oestrous cycle. The effect on PGE2 output depended on the age of the animals and was absent in younger guinea-pigs (< 4 months). Theophylline also stimulated the outputs of PGF2 alpha and 6-keto-PGF1 alpha, but not the output of PGE2, from the day 7 guinea-pig uterus. 2. The stimulatory effects of caffeine on the outputs of PGF2 alpha, PGE2 and 6-keto-PGF1 alpha from the guinea-pig uterus were not prevented by lack of extracellular calcium, ryanodine or ruthenium red (both inhibitors of calcium release via the ryanodine receptor), although the increase in PGF2 alpha output tended to be slower when extracellular calcium was absent. Also, ryanodine flattened and broadened the peak of increased PGF2 alpha release. 3. The calmodulin antagonists, W-7 and trifluoperazine, had no inhibitory effect on the caffeine-stimulated increases in uterine prostaglandin output. In fact, W-7 (but not trifluoperazine) greatly potentiated the action of caffeine on uterine PGF2 alpha output, but had little or no potentiating effect on the action of caffeine on uterine PGE2 and 6-keto-PGF1 alpha outputs. 4. TMB-8, an intracellular calcium antagonist, inhibited the increase in PGF2 alpha output produced by caffeine without preventing the increases in outputs of PGE2 and 6-keto-PGF1 alpha. 5. These studies suggest that caffeine stimulates uterine PGF2 alpha synthesis and release by a mechanism dependent upon intracellular calcium, but this mechanism is not mediated by activation of any of the three well-characterized ryanodine receptors or by calmodulin. Furthermore, the increases in the synthesis and release of PGE2 and 6-keto-PGFI alpha. in the guinea-pig uterus induced by caffeine appear to involve mechanism(s) different from that which stimulates PGF2 alpha production.

Nonsteroidal antiinflammatory drugs and reproduction

The role of nonsteroidal antiinflammatory drugs in human reproduction and reproductive disorders is reviewed. Nonsteroidal antiinflammatory drugs inhibit the biosynthesis of prostanoids and can cross the placental barrier into the fetal circulation. Nonsteroidal antiinflammatory drugs are the treatment of choice in primary dysmenorrhea and intrauterine contraceptive device-induced dysmenorrhea and menorrhagia. Nonsteroidal antiinflammatory drugs can be used for effective control of menorrhagia, preterm labor, and polyhydramnios and for prevention of preeclampsia, but larger definitive clinical trials are needed. Prostaglandin inhibition with some nonsteroidal antiinflammatory drugs appear promising in the relief of some premenstrual symptoms and in the prevention of postoperative pelvic adhesion formation, but more studies are needed in women. Whereas implantation and tubal mobility are mediated by local prostaglandins, the potential use of nonsteroidal antiinflammatory drugs to suppress prostaglandin in these reproductive processes for enhancing or reducing fertility warrants further studies. In the last 2 decades nonsteroidal antiinflammatory drugs have been used increasingly in the treatment of some reproductive disorders and are promising for many others.

Effects of mefenamic acid on menstrual hemostasis in essential menorrhagia

Prostaglandin synthesis inhibitors decrease menstrual blood loss by 30% to 50% in patients with essential menorrhagia. To obtain insight into their mechanism of action, we measured menstrual blood loss in menorrhagic women, who were receiving mefenamic acid (500 mg, three times daily) (n = 6) or placebo (n = 5) in a double-blind way. In addition we studied the morphology of early menstrual hemostasis. The subjects' uteri were extirpated in the first 24 hours of menstruation, and light and electron microscopy were used to perform morphologic and morphometric studies. In the group treated with mefenamic acid mean menstrual blood loss was decreased by 40%. In uteri of the women treated with mefenamic acid hemostatic plugs were further transformed, and fewer vessels without a plug were observed than in uteri of the group receiving placebo. These data suggest that mefenamic acid may act through an improvement of platelet aggregation and degranulation and through increased vasoconstriction.

Phospholipase activity in the endometrium of women with normal menstrual blood loss and women with proven ovulatory menorrhagia

The activity of phospholipase A2 types 1 and 2 and phospholipase C was measured in the endometrium of women with ovulatory menorrhagia and in those with normal menstrual blood loss. In both groups of subjects phospholipase A2 type 1 activity was significantly higher in the secretory phase than in the proliferative phase (P less than 0.001). The median activity (pmol/mg protein/min) for the proliferative phase was 27.6 in normal subjects and 40.4 in women with ovulatory menorrhagia and for the secretory phase the median activity was 144.5 in normal women and 138.1 in women with ovulatory menorrhagia. There was no difference between the two groups of women at either stage of the cycle. Phospholipase A2 type 2 activity was also higher in the secretory phase than in the proliferative phase (P less than 0.05 for normal subjects and P less than 0.001 for women with menorrhagia). The median activity (pmol/mg protein/min) for the proliferative phase was 94.4 (normal subjects) and 56.6 (women with menorrhagia) and for the secretory phase 148.3 (normal subjects) and 142.5 (women with menorrhagia). The activity of phospholipase A2 type 2 was significantly lower in the proliferative phase of women with ovulatory menorrhagia compared with normal subjects (P less than 0.05). Phospholipase C activity (nmol/mg protein/min) was significantly higher in women with ovulatory menorrhagia (median 8.2) compared with women with normal blood loss (median 5.5) (P less than 0.01).

A comparison of flurbiprofen, tranexamic acid, and a levonorgestrel-releasing intrauterine contraceptive device in the treatment of idiopathic menorrhagia

Treatment with flurbiprofen (100 mg twice a day for 5 days), tranexamic acid (1.5 gm three times a day for 3 days and 1 gm twice a day for another 2 days), and an intrauterine contraceptive device releasing 20 micrograms levonorgestrel per day was compared in women with idiopathic menorrhagia. The menstrual blood loss during two control periods in 15 women subsequently treated with flurbiprofen and tranexamic acid was 295 +/- 52 ml and 203 +/- 25.2 ml in the 16 women later fitted with a levonorgestrel-releasing intrauterine contraceptive device. Menstrual blood loss was reduced by all three forms of treatment. The reduction in menstrual blood loss expressed as a percentage of the mean of two control cycles for each form of treatment was as follows: flurbiprofen, 20.7% +/- 9.9%; tranexamic acid, 44.4% +/- 8.3%; levonorgestrel-releasing intrauterine contraceptive device after 3 months, 81.6% +/- 4.5%; levonorgestrel-releasing intrauterine contraceptive device after 6 months, 88.0% +/- 3.1%; levonorgestrel-releasing intrauterine contraceptive device after 12 months, 95.8% +/- 1.2%. The reduction in menstrual blood loss achieved by the levonorgestrel-releasing intrauterine contraceptive device was greater than that recorded with flurbiprofen (p less than 0.001) and tranexamic acid (p less than 0.01), and was greater for tranexamic acid when compared with flurbiprofen (p less than 0.05). The levonorgestrel-releasing intrauterine contraceptive device was the only form of treatment to reduce mean menstrual blood loss below 80 ml per menstruation, the upper limit of normal menstrual blood loss.

Management of IUD-associated menorrhagia in female rhesus monkeys (Macaca mulatta)

The study was undertaken to evaluate the effect of antifibrinolytic agents (epsilon-aminocaproic acid, EACA; tranexamic acid, AMCA), anti-inflammatory drugs (indomethacin, IND; ibuprofen, IBU; naproxen, NAP) and root extract of the plant Boerhaavia diffusa (BD) on menstrual cycle length (MCL), duration of menstrual flow (DMF), menstrual iron loss (MIL) and activity of uterine tissue plasminogen activator (tPA) in IUD-fitted monkeys. Premature onset of menstruation was observed in IUD-fitted monkeys (26.0 +/- 0.7 days, mean +/- SE) as compared to controls (28.7 +/- 0.4 days). No noteworthy change was observed in the MCL of drug treated monkeys as compared to IUD-fitted monkeys. An increase of 155%, 123.2%, and 288% was observed in the DMF, MIL and tPA activity after IUD insertion as compared to controls. Antifibrinolytic agents reduced the DMF, MIL and activity of tPA in IUD-fitted monkeys up to 117.4%, 116.4%, and 254%, whereas anti-inflammatory drugs caused a decrease only up to 69%, 95.1%, and 138%, respectively. Conclusively, root extract of B. diffusa treated IUD-fitted monkeys showed noticeable reduction in their DMF (124%), MIL (120.8%) and tPA activity (272%).

Management of cyclical menorrhagia with prostaglandin synthetase inhibitor

A well controlled double blind prospective trial was undertaken to determine the efficacy of mefenamic acid in the treatment of menorrhagia. Eighty patients who had unexplained cyclical menorrhagia with secretory endometrium received mefenamic acid orally in a dose of 500 mg 8 hourly or a placebo tablet thrice daily starting from day-one of the cycle for 5 days or till cessation of menses. Mefenamic acid administration caused a statistically significant reduction in the number of days of bleeding from 9.7 +/- 3.1 days before treatment to 4.1 +/- 0.6 days after treatment. It also brought about significant reduction in the amount of bleeding in terms of number of pads used per day, that is from 15.2 +/- 3.1 before treatment to 6.5 +/- 0.02 after treatment. Eighty-six percent patients in the treatment group had control of menorrhagia with the drug compared to 20% in the control group without drugs and this difference was statistically significant. Mefenamic acid proved to be a potent and efficacious agent in the control of unexplained menorrhagia.

The presence of prostacyclin binding sites in nonpregnant bovine uterine tissue

Myometrium of various animal species makes a considerable amount of prostacyclin (PGI2) which is a potent myometrial and uterine vascular smooth muscle relaxing agent. This action of PGI2 is perhaps mediated by binding to specific receptors, which have never been demonstrated in uterine tissue of any animal species until very recently. The quantitative light microscopic autoradiographic approach used in the present studies demonstrated that while bovine myometrial smooth muscle and uterine vascular smooth muscle contained PGI2 specific binding sites, endometrial and perimetrial cells contained few or no binding sites. The number of binding sites in circular and elongated myometrial smooth muscle and in arteriolar smooth muscle were similar (P greater than 0.05). The PGI2 binding to the uterine cells was greatly reduced (P less than 0.001) following coincubation with excess unlabeled PGI2, but not with its stable metabolite, 6-keto PGF1 alpha, PGE2, PGF2 alpha and leukotriene C4 which bind to nonpregnant bovine uterine tissue, also had no effect of PGI2 binding. In conclusion, nonpregnant bovine uterine tissue contain specific PGI2 binding sites which may mediate its potent relaxing effect on myometrium and uterine vasculature.