A longitudinal study of changes in endometrial microvascular density in Norplant implant users

Gene expression associated with unfavorable vaginal bleeding in women using the etonogestrel subdermal contraceptive implant: a prospective study

To evaluate gene expression associated with unfavorable vaginal bleeding in users of the Etonogestrel (ENG) contraceptive implant. Prospective study involving 100 women who intended to use the ENG implant. Exclusion criteria included abnormal uterine bleeding, inability to attend a 1-year follow-up, and implant removal for reasons unrelated to vaginal bleeding or loss of follow-up. We obtained endometrial biopsies before implant placement and assessed the expression of 20 selected genes. Users maintained a uterine bleeding diary for 12 months post-implant placement. For statistical analysis, we categorized women into those with or without favorable vaginal bleeding at 3 and 12 months. Women with lower CXCL1 expression had a 6.8-fold increased risk of unfavorable vaginal bleeding at 3 months (OR 6.8, 95% CI 2.21-20.79, p < 0.001), while those with higher BCL6 and BMP6 expression had 6- and 5.1-fold increased risks, respectively. By the 12-month follow-up, women with lower CXCL1 expression had a 5.37-fold increased risk of unfavorable vaginal bleeding (OR 5.37, 95% CI 1.63-17.73, p = 0.006). Women with CXCL1 expression < 0.0675, BCL6 > 0.65, and BMP6 > 3.4 had a higher likelihood of experiencing unfavorable vaginal bleeding at 3 months, and CXCL1 < 0.158 at 12 months. Users of ENG contraceptive implants with elevated BCL6 and BMP6 expression exhibited a higher risk of breakthrough bleeding at the 3-month follow-up. Conversely, reduced CXCL1 expression was associated with an elevated risk of bleeding at both the 3 and 12-month follow-ups.

In vivo effects of AZD4547, a novel fibroblast growth factor receptor inhibitor, in a mouse model of endometriosis

Endometriosis is a chronic disease, characterized by the growth of endometrial-like cells outside the uterine cavity. Due to its complex pathophysiology, a totally resolving cure is yet to be found. The aim of this study was to compare the therapeutic efficacy of AZD4547, a novel fibroblast growth factor receptor inhibitor (FGFRI), with a well-characterized progestin, etonogestrel (ENG) using a validated in vivo mouse model of endometriosis. Endometriosis was induced by transplanting uterine fragments from donor mice in proestrus into the peritoneal cavity of recipient mice, which then developed into cyst-like lesions. AZD4547 and ENG were administered systemically either from the day of endometriosis induction or 2-weeks post-surgery. After 20 days of treatment, the lesions were harvested; their size and weight were measured and analyzed histologically or by qRT-PCR. Stage of estrous cycle was monitored throughout. Compared to vehicle, AZD4547 (25 mg/kg) was most effective in counteracting lesion growth when treating from day of surgery and 2 weeks after; ENG (0.8 mg/kg) was similarly effective in reducing lesion growth but only when administered from day of surgery. Each downregulated FGFR gene expression (p < 0.05). AZD4547 at all doses and ENG (0.008 mg/kg) caused no disturbance to the estrous cycle. ENG at 0.08 and 0.8 mg/kg was associated with partial or complete estrous cycle disruption and hyperemia of the uteri. AZD4547 and ENG both attenuated endometriotic lesion size, but only AZD4547 did not disrupt the estrous cycle, suggesting that targeting of FGFR is worthy of further investigation as a novel treatment for endometriosis.

Effects of progestin-only contraceptives on the endometrium

INTRODUCTION

The contraceptive activity of synthetic progestins is mediated through three basic mechanisms: (a) An anti-gonadotrophic action leading to the inhibition of ovulation; (b) Changes in cervical mucus characteristics that inhibit sperm penetration and (c) desynchronization of the endometrial picture necessary for implantation.

AREAS COVERED

Mechanisms involved in the progestin-induced endometrium desynchronization are individually reviewed for each of the routes of administration and, whenever possible, by individual members of the various families of synthetic progestin derivatives.

EXPERT OPINION

For contraceptive purposes, progestins are today administered through several routes: orally, as injections, subdermally and via the vagina or the uterine cavity. Given this variety of modalities, their effects may differ, depending on the route of administration, concentration reached at the level of the endometrium and the duration of use. These are characterized by inactivation of the endometrium. Progestin-only contraception provides a safe and effective control of fertility regulation, although, they are associated with the problem of endometrial break through bleeding that may lead to discontinuation. Unfortunately, in spite of a major research effort over two decades, there is not, as yet, an established long-term intervention available to manage bleeding irregularities, making mandatory a deeper understanding of the mechanisms involved is required.

High dose of green tea infusion normalized spiral artery density in rats treated with the depot-medroxyprogesterone acetate

Aim:

The purpose of this study was to investigate the effects of green tea (GT) on the spiral artery density and endometrial thickness in female rats treated with the depot-medroxyprogesterone acetate (DMPA).

Material and Methods:

A total of 24 female rats were randomly divided into four groups (n = 6 each): The control group (no treatment), the DMPA-treated group, treated with DMPA and GT doses of 165 mg/kg of body weight/day, and treated with DMPA and GT doses of 330 mg/kg of body weight/day. Spiral artery density and endometrial thickness were subjected to histopathological analysis.

Results:

Spiral artery density decreased in the DMPA-treated group, despite the insignificant difference (P > 0.05). With regard to the administration of GT at doses of 165 and 330 mg/g of body weight/day, only GT at the high dose was capable of significantly preventing a decrease in spiral artery density (P < 0.05). At this dose, the spiral arteries achieved a density comparable to that of the control group (P > 0.05). Meanwhile, the administration of DMPA and/or DMPA with GT did not cause significant changes in endometrial thickness relative to the control group (P > 0.05).

Conclusions:

DMPA induced a decrease in spiral artery density, despite the insignificant differences, and these changes could be normalized by the administration of high doses of GT. Therefore, GT could be a candidate herb to prevent the adverse effects of the contraceptive DMPA.

Effects of an ethinyl estradiol/gestodene transdermal contraceptive patch on the endometrium: a single-center, uncontrolled study

AIM

This study aims to investigate the effect of a transdermal contraceptive patch containing ethinyl estradiol and gestodene on endometrial proliferation over 1 year.

MATERIALS & METHODS

In this open-label, uncontrolled, Phase IIb study, women (aged 18-35 years) used the patch for 13 cycles of 28 days. The primary variable was histologic endometrial effects at cycle 13. Secondary objectives included contraceptive efficacy and safety.

RESULTS

Overall, 89 women were treated. At all visits, endometrial biopsies were devoid of any abnormalities. One woman became pregnant. The patch was well tolerated, with no safety concerns.

CONCLUSION

The ethinyl estradiol and gestodene patch had an endometrial effect consistent with suppression of endometrial proliferation in most patients. No endometrial abnormalities or other concerns were reported; compliance was good.

Long-term progestin contraceptives (LTPOC) induce aberrant angiogenesis, oxidative stress and apoptosis in the guinea pig uterus: A model for abnormal uterine bleeding in humans

Background

Irregular uterine bleeding is the major side effect of, and cause for, discontinuation of long-term progestin-only contraceptives (LTPOCs). The endometria of LTPOC-treated women display abnormally enlarged, fragile blood vessels (BV), decreased endometrial blood flow and oxidative stress. However, obtaining sufficient, good quality tissues have precluded elucidation of the mechanisms underlying these morphological and functional vascular changes.

Methods

The current study assessed the suitability of the guinea pig (GP) as a model for evaluating the uterine effects of LTPOC administration. Thus GPs were treated with a transdermal pellet for 21 days and examined for endometrial histology, angiogenic markers as well as markers of oxidative stress and apoptosis.

Results and Discussion

We now demonstrate that GP uteri were enlarged by both estradiol (E2) and medroxyprogesterone acetate (MPA) (p < 0.001). Effects of MPA on uterine weight differed significantly depending on E2 levels (p < 0.001), where MPA opposed the E2 effect in combined treatments. Angiogenesis parameters were similarly impacted upon: MPA alone increased BV density (p = 0.036) and BV average area (p = 0.002). The presence of E2 significantly decreased these parameters. These changes were associated with highly elevated of the lipid peroxidation product, 8-isoprostane (8-isoP) content in E2+MPA-treated and by nuclear 8-OH-deoxyguanosine (8oxoG) staining compared to all other groups (p < 0.001). Abnormalities in the E2+MPA group were consistent with chromatin redistribution, nuclear pyknosis, karyolysis and increased apoptosis as observed by a marked increase in TUNEL labeling.

Conclusions

LTPOC exposure alters endometrial vascular and tissue morphology consistent with oxidative stress and apoptosis in a complex interplay with endogenous estrogens. These findings are remarkably similar to in vivo change observed in the human uterus following LTPOC administration. Hence, the GP is an excellent model for the study of LTPOC effects on the uterus and will be extremely useful in determining the mechanistic pathways involved in this process which cannot be conducted on humans.

Development of an animal experimental model to study the effects of levonorgestrel on the human endometrium

BACKGROUND

This study was designed to develop an animal model to test the response of endometrium to local progestin delivery.

METHODS

Proliferative human endometrium was subcutaneously grafted in two groups of SCID mice that received, 2 days before, a subcutaneous estradiol (E(2)) pellet and, for half of them, an additional implant of levonorgestrel (LNG). Mice were sacrificed 1, 2, 3 or 4 weeks after endometrial implantation and grafts were histologically analysed. Proliferation, steroid hormone receptors, blood vessels and stromal decidualization in both groups (E(2) and LNG) were immunohistologically evaluated and compared with proliferative endometrium and endometrium from women with an LNG intrauterine device.

RESULTS

Grafts presented normal morphological endometrial characteristics. The expression of progesterone receptors was significantly decreased in glands and stroma of the LNG group as compared with the E(2) group at all times. A significant decrease was also observed in the stromal expression of estrogen receptor-alpha in the LNG group. At 4 weeks, the mean cross-sectional area of vessels was significantly higher after LNG treatment.

CONCLUSIONS

These morphological and immunohistochemical characteristics are similar to those observed in women treated with local LNG. This mouse model might facilitate further investigations needed to understand the mechanisms responsible for the breakthrough bleeding frequently observed in progestin users.

Endometrial structural and inflammatory changes with exogenous progestogens

Safe and effective contraception is an international public health priority. The long-acting progestogen-only contraceptives are used by over 20 million women worldwide but their main drawback is abnormal uterine bleeding. Such bleeding arises owing to structural and inflammatory changes which compromise endometrial microvascular and epithelial integrity. The molecular and structural changes that lead to the vessel and surface epithelial fragility, and hence the side effect of abnormal uterine bleeding commonly seen with exogenous progestogen use, might be lessened by short-term treatments shown to shorten bleeding episodes.

Endometrial effects of intrauterine levonorgestrel

Local intrauterine delivery of levonorgestrel (LNG) results in extensive decidualization of endometrial stromal cells, atrophy of the glandular and surface epithelium and changes in vascular morphology (suppression of spiral artery formation and presence of large dilated vessels). With endometrial exposure to LNG, there is down-regulation of sex steroid receptors in all cellular components. As a consequence of endometrial sex steroid receptor down-regulation, there is perturbation of progesterone-regulated locally acting mediators, and the integrity of blood vessel walls is disturbed. Thus, intrauterine LNG administration results in modulation of local mediators regulating endometrial function. To date, no single factor has been identified where the expression correlates closely with unscheduled breakthrough bleeding (BTB). BTB is a common side effect and reason for discontinuation of LNG-IUS use. Much remains to be determined about the mechanisms involved in suppression of menstruation, BTB episodes and the local endometrial environment with local LNG administration.

Doxycycline alters the expression of inflammatory and immune-related cytokines and chemokines in human endometrial cells: implication in irregular uterine bleeding*

BACKGROUND

Increased production of pro-inflammatory mediators is considered central in the manifestation of events leading to irregular uterine bleeding in progestin-only contraceptive users. Evidence suggests that in addition to its antimicrobial property, doxycycline (Dox) acts as an anti-inflammatory agent mainly through the suppression of pro-inflammatory mediators.

METHODS

We tested this hypothesis in the endometrial environment using an in vitro model consisting of isolated human endometrial glandular epithelial and stromal cells and a human endometrial surface (HES) epithelial cell line cultured under defined conditions.

RESULTS

We found that Dox at doses ranging from 1 to 100 microg/ml had a limited growth-inhibitory effect on these cells, whereas Dox in a dose-dependent manner inhibited the production of tumour necrosis factor-alpha (TNF-alpha). Using multiplex cytokine/chemokine protein analysis to test a broader range of Dox activity, we found that Dox at 25 microg/ml either alone or in the presence of 17beta-estradiol (E2), medroxyprogesterone acetate (MPA) and E2+MPA (10(-8) M) as well as TNF-alpha (25 ng/ml), representing the endometrial environment exposed to contraceptives as well as inflammatory conditions, respectively, altered the production of multiple cytokines and chemokines as compared with untreated controls. These actions of Dox occurred in cell-, ovarian steroid- and cytokine/chemokine-dependent manners. Although Dox reduced the regulatory action of steroids on the production of these cytokines/chemokines, it was less effective on TNF-alpha-treated cells.

CONCLUSIONS

The results support the hypothesis that Dox, by modulating the endometrial expression of multiple inflammatory-related cytokines/chemokines in a cell- and cytokine/chemokine-dependent manner, may have a therapeutic potential in patients experiencing irregular uterine bleeding, in particular in progestin-dominant contraceptive users.

Endometrial histology, microvascular density and caliber, and matrix metalloproteinase-3 in users of the Nestorone®-releasing contraceptive implant with and without endometrial breakthrough bleeding

OBJECTIVE

This descriptive study evaluated endometrial histology, microvascular density and caliber, and quantification of matrix metalloproteinase (MMP-3) expression in long-term users of the Nestorone (NES)-releasing implant who presented or not endometrial breakthrough bleeding (BTB).

METHODS

Endometrial biopsies were obtained from 32 healthy women with unpredictable BTB. The quantitative analysis was performed only in 20 samples.

RESULTS

The mean duration of use of the implant among the 14 women with BTB was 19.6+/-1.0 months, and the other six women had used the implant for 17.7+/-2.3 months (mean+/-S.E.M.). Histological analysis of the endometrial tissue showed a predominance of progestogenic pattern followed by atrophic and proliferative endometrium in both groups. Mucosal breakdown and glandular pseudostratification were observed in half of the cases. Endometrial vascular density was 73.1+/-10.0 and 57.5+/-24.1 vessels/mm(2), and maximum vessel diameter was 923.3+/-86.0 and 1038.0+/-404 microm (mean+/-S.E.M.) in the group with and without BTB, respectively, without significance, and the rate of cells expressing MMP-3x1000 counted stromal cells was 155.8+/-24.8 and 127.0+/-19.0 (mean+/-S.E.M.) in both groups, respectively, without significance.

CONCLUSIONS

This study provides information about some endometrial aspects of women using NES in contraceptive implants. In addition, the endometrium was similar during long-term use of NES-releasing contraceptive implants in women with and without endometrial bleeding.

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.

Progestogen only contraception and endometrial break through bleeding

Progestogen only contraceptives (POC) provide a safe and effective method of fertility regulation. Unfortunately, they are commonly associated with the problem of endometrial break through bleeding (BTB), often leading to discontinuation of use. An increase in endometrial vascular fragility has been demonstrated as an important mechanism that contributes to BTB but our understanding of the interaction between exogenous steroid use and endometrial vasculature remains incomplete. This review sets out to describe a number of commonly used POC, their effects on endometrial morphology and possible molecular and cellular mechanisms that may lead to unscheduled bleeding.

Recent advances in endometrial angiogenesis research

This review summarises recent research into the mechanisms and regulation of endometrial angiogenesis. Understanding of when and by what mechanisms angiogenesis occurs during the menstrual cycle is limited, as is knowledge of how it is regulated. Significant endometrial endothelial cell proliferation occurs at all stages of the menstrual cycle in humans, unlike most animal models where a more precise spatial relationship exists between endothelial cell proliferation and circulating levels of oestrogen and progesterone. Recent stereological data has identified vessel elongation as a major endometrial angiogenic mechanism in the mid-late proliferative phase of the cycle. In contrast, the mechanisms that contribute to post-menstrual repair and secretory phase remodelling have not yet been determined. Both oestrogen and progesterone/progestins appear to have paradoxical actions, with recent studies showing that under different circumstances both can promote as well as inhibit endometrial angiogenesis. The relative contribution of direct versus indirect effects of these hormones on the vasculature may help to explain their pro- or anti-angiogenic activities. Recent work has also identified the hormone relaxin as a player in the regulation of endometrial angiogenesis. While vascular endothelial growth factor (VEGF) is fundamental to endometrial angiogenesis, details of how and when different endometrial cell types produce VEGF, and how production and activity is controlled by oestrogen and progesterone, remains to be elucidated. Evidence is emerging that the different splice variants of VEGF play a major role in regulating endometrial angiogenesis at a local level. Intravascular neutrophils containing VEGF have been identified as having a role in stimulating endometrial angiogenesis, although other currently unidentified mechanisms must also exist. Future studies to clarify how endometrial angiogenesis is regulated in the human, as well as in relevant animal models, will be important for a better understanding of diseases such as breakthrough bleeding, menorrhagia, endometriosis and endometrial cancer.

Influence of different hormonal regimens on endometrial microvascular density and VEGF expression in women suffering from breakthrough bleeding

BACKGROUND

The aim of this study was to quantify blood vessel density (BVD) and immunoreactive vascular endothelial growth factor (VEGF) levels in endometrial biopsies taken from women suffering breakthrough bleeding (BTB) under different exogenous hormonal regimes.

METHODS

Endometrial biopsies from women in Melbourne with BTB were divided into four groups: combined-continuous hormone therapy (HT) (estrogen and progestin taken daily), cyclical HT (daily estrogen with progestin for 14 days each cycle), progestin-only, or no HT. Subjects from Barcelona were using the Mirena intrauterine levonorgestrel-releasing system for contraceptive purposes, with menstrual diaries for classification into four groups (amenorrhea, infrequent, regular and prolonged). Control biopsies from Melbourne were included in the study. Endometrial samples were immunostained for VEGF and blood vessel localization using an antibody to CD34.

RESULTS

Results showed that BVD was significantly reduced in the progestin-only treated group compared with the other three treatment groups (P = 0.028). In addition, all four Mirena BTB groups had significantly reduced BVD compared with controls. Considerable heterogeneity was observed in VEGF immunostaining within and between individual samples with no major differences between HT or Mirena.

CONCLUSION

These results provide strong evidence that unopposed progestins reduce endometrial BVD and that there is no link between VEGF immunostaining and BVD or BTB.

Histological characteristics and altered expression of interleukins (IL) IL-13 and IL-15 in endometria of levonorgestrel users with different uterine bleeding patterns

OBJECTIVE

To determine the relationship between uterine bleeding patterns in levonorgestrel users with endometrial histology and expression of interleukins (IL) IL-13 and IL-15.

DESIGN

Prospective observational study.

SETTING

Academic research center.

PATIENT(S)

Questionnaires were sent to patients (n = 578) who had levonorgestrel implants concerning bleeding patterns; 35 of these patients were identified to have regular cycle (n = 13), amenorrhea (n = 8), or metrorrhagia (n = 14).

INTERVENTION(S)

Endometrial biopsies, serum, histology, and immunostaining.

MAIN OUTCOME MEASURE(S)

Endometrial histological assessment and immunostaining for IL-13 and IL-15 and for blood levonorgestrel, E2, and progesterone levels by ELISA or RIA.

RESULT(S)

No correlation was found between circulating levonorgestrel, E2, or progesterone levels with the bleeding patterns, although a trend toward a lower E2 level was observed in patients with amenorrhea who had inactive endometrium. There was a direct correlation between bleeding patterns and endometrial histology, as well as IL-13 and IL-15 expression in patients with regular cycles and metrorrhagia, demonstrating secretory and proliferative endometrium, respectively. Some patients in each group were also identified as demonstrating endometritis.

CONCLUSION(S)

Endometrial histology may assist directing therapy and subsequently increasing compliance in progestin-only contraceptive users with irregular bleeding who fail to respond to standard therapies. Altered endometrial expression of IL-13 and IL-15, key cytokines in inflammatory and immune cell trafficking, may influence events, leading to irregular bleeding.

Endometrial vascularization in levonorgestrel intrauterine device users; computerized microvessel measurement study

Levonorgestrel use in the levonorgestrel intrauterine device (LNG-IUS) induces vascular distension within the superficial layer of the endometrium and massive pseudodecidualization. With a computer-assisted image analysis system, we objectively measured the vascular bed in LNG-IUS users and compared it to the physiological endometrium. A study was undertaken on 25 women using LNG-IUS, in an outpatient procedure at the time of removal of the IUS and compared with 11 normally cycling women (control group). Suction curette specimens were obtained just after retrieval of the IUS, and immunohistochemistry was carried out with a specific marker of the endothelial cells (CD31). Number of vessels decreased in the LNG-IUS group to 60/mm2 versus 124/mm2 in the control group, and mean vessel area increased to 1255 microm2 versus 157 microm2, respectively, in the control group. The decrease in mean vascular density and the increase of mean vessel area in the LNG-IUS group, compared to the control group, were both highly significant (p<.001).

Increased serum levels of nitric oxide metabolites among users of levonorgestrel-releasing implants [corrected] a possible role in progestin-induced bleeding

BACKGROUND

Nitric oxide (NO) is a potent angiogenic and vasodilator factor that could be involved in progestin-induced bleeding. This study aimed to assess possible changes in the serum levels of NO metabolites in users of levonorgestrel-releasing implants (LNG-implants) [corrected] and to identify any correlation between some of their clinical characteristics and NO metabolite levels.

METHODS

This cross-sectional study included 37 LNG-implants [corrected] users; a single 5 ml venous blood was collected at different periods of [corrected] use. Women were divided into users with acceptable menstrual bleeding (n 5 13) [corrected] and those having abnormal bleeding patterns (n 5 24) [corrected] The controls are 13 age-matched healthy women; they were fertile, had regular menstruation and did not use any contraceptive method in the previous 3 months. NO was determined by the evaluation of its oxidation products (nitrites and nitrates) where the nitrates were reduced to nitrites with cadmium filings; total serum concentrations of nitrites were measured by using the Griess reaction.

RESULTS

The mean serum levels of NO metabolites were significantly higher in the LNG-implants [corrected] users than in the controls (mean+/-SE) 34.9+/-11.3 versus 6.1+/-1.5 mumol/l (P<0.001) [corrected] The mean serum levels of NO metabolites were significantly higher in the LNG-implants [corrected] users with abnormal bleeding patterns than in those with normal bleeding patterns (mean+/-SE) 41.3+/-7.4 versus 23.2+/-5.8 mumol/l (P<0.001) [corrected] There was a positive correlation between NO levels and both prolonged spotting and heavy/prolonged bleeding days (P<0.001 and P<0.01, respectively) and negative correlation between NO levels with the duration of use and length of the menstrual cycle (P<0.05).

CONCLUSION

The significantly increased serum levels of NO metabolites among LNG-implants [corrected] users may primarily reflect an increase in its endometrial production, possibly secondary to its increased liberation by systemic vascular endothelium. This may result in enhanced endometrial angiogenesis and vascular dilatation which can induce and perpetuate abnormal excessive/prolonged uterine bleeding.

Effect of long-term progestin treatment on endometrial vasculature in normal cycling mice

The aim of this study was to develop a mouse model to investigate the effects of long-term progestin-only exposure on endometrial vascular structure. Normal cycling mice received Silastic implants containing either medroxyprogesterone acetate (MPA) or levonorgestrel (LNG) and were dissected after 1, 3 or 6 weeks. Endometrial vascular density increased significantly within 1 week of MPA (482 +/- 40.2 vessels/mm2) or LNG (440 +/- 26.5 vessels/mm2) treatment compared with normal cycling mice (293 +/- 10.5 vessels/mm2). MPA increased stromal cell density within 1 week of treatment (13813 +/- 1450 cells/mm2) compared with normal cycling mice (8256 +/- 928 cells/mm2). However, although LNG significantly increased stromal cell density overall, the increase did not reach significance within the individual weeks examined. There was no significant change in the ratio of vascular to stromal cell density among treated and normal cycling mice. Epithelial cell height significantly decreased within 1 week of LNG (17.6 +/- 1.3 microm) treatment compared with normal cycling mice (23.5 +/- 1.3 microm); epithelial cell height also decreased within 1 week of MPA treatment (16.6 +/- 2.1 microm), although this did not reach statistical significance. VEGF immunostaining increased significantly in luminal epithelium after MPA or LNG treatment, and in glandular epithelium after LNG treatment. These observations are similar to those reported in human endometrium, suggesting that this mouse model may facilitate further investigations into breakthrough bleeding due to long-term progestin use.

A three-dimensional study of endometrial microvessels in women using the contraceptive subdermal levonorgestrel implant system, norplant®

Recent evidence points towards a substantial disturbance of the process of angiogenesis within the endometrium in women who are exposed continuously to low dose contraceptive progestogens. This results in the patchy appearance of abnormally small and abnormally large, thin-walled vessels in the superficial regions of exposed endometrium. Three-dimensional pictures were developed from digitised images of serial tissue sections of endometrium in which microvascular endothelial cells were labelled with antibodies to the endothelial cell surface antigen, CD34 and their basement membranes labelled with anti-Collagen IV antibodies. Microvessels from endometrium exposed to continuous low-dose levonorgestrel from a subdermal implant system (Norplant) displayed considerable variations in size and shape. No spiral arterioles were identified. Some microvessels showed considerable dilatation, distortion and variability in the presence of surrounding basement membrane components. Other endothelial structures included narrow, solid cords of endothelial cells, without basement membranes, which often connected with normal or abnormal vessels containing lumens. Some areas, especially deeper in the tissue, contained microvessels of normal size and shape surrounded by basement membrane. These images have revealed an overall picture of great variability in superficial endometrial vascular structures in some women using a low-dose levonorgestrel implant system which appears substantially different from that seen in normal endometrium.

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.

Menstrual disorders in adolescence

Problems associated with menstruation affect 75% of adolescent females and are a leading reason for visits to physicians. This chapter begins with a review of the timing and characteristics of normal menstruation during adolescence. It then discusses the evaluation and management of adolescents with amenorrhoea, dysmenorrhoea and abnormal uterine bleeding. An approach to adolescent amenorrhoea is presented that utilizes primary versus secondary amenorrhoea, delayed versus normal pubertal development, and the presence or absence of hyperandrogenism as nodal points for decision making. The differential diagnosis of dysmenorrhoea and the management of primary dysmenorrhoea and endometriosis are reviewed. The section on abnormal uterine bleeding contrasts anovulatory dysfunctional uterine bleeding (DUB) with bleeding secondary to problems of pregnancy, uterine pathology, exogenous hormone use and systemic bleeding disorders.

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

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

In-vivo angiogenesis and progestogens

BACKGROUND

Progestogens are used clinically for contraception, to control excessive menstrual bleeding, and to prevent estrogen-induced endometrial hyperplasia. A significant problem with progestogen-only methods of contraception is the induction of breakthrough bleeding.

METHODS

The effects of different progestogens on angiogenesis were examined using two approaches. The mouse sponge angiogenesis assay employed direct delivery of the dose ranges achieved therapeutically. The angiogenic response to long-term intrauterine levonorgestrel exposure, compared with unexposed premenopausal endometrium, was also studied.

RESULTS

In the mouse sponge assay, norethisterone and medroxyprogesterone acetate stimulated angiogenesis at all doses, but was dose-dependent for levonorgestrel and nomegestrol. Levonorgestrel stimulated angiogenesis in the dose range 100 pmol/l to 10 nmol/l, but not at higher doses. In contrast, nomegestrol acetate stimulated angiogenesis at high, but not low, doses. Expression of acidic and basic fibroblast growth factors, thymidine phosphorylase, vascular endothelial growth factor and adrenomedullin were unaltered in levonorgestrel-exposed endometrium compared with premenopausal controls. Vascular density was increased but endothelial proliferation reduced in levonorgestrel-exposed endometrium.

CONCLUSIONS

This is the first report of the direct effects of a wide range of doses of different progestogens on angiogenesis; results suggest that vascular targeting may be an effective strategy to deal with progestogen-induced abnormal bleeding.

Administration of an antiprogesterone up-regulates estrogen receptors in the endometrium of women using Norplant: a pilot study

OBJECTIVE

To determine the effect of a single dose of mifepristone (200 mg) on endometrial estrogen and progesterone receptors in Norplant users.

DESIGN

A prospective single-blind placebo-controlled pilot study. SETTING; Women were recruited from a large family planning clinic and were studied either at the clinic or in a clinical research unit attached to a teaching hospital gynecology department.

PATIENT(S)

Eight women using Norplant and experiencing vaginal bleeding more often than once every 24 days. All completed the study.

INTERVENTION(S)

Endometrial biopsies were taken after treatment with both placebo and 200 mg of mifepristone, both given at the start of a bleeding episode.

MAIN OUTCOME MEASURE(S)

Expression of endometrial progesterone (PR) and estrogen (ER) receptors, ovulation, and vaginal bleeding.

RESULT(S)

Mifepristone administration was associated with down-regulation of PR receptor subtype B and up-regulation of ER. Women treated with mifepristone showed a tendency to increased ovulation rates and reduced vaginal bleeding.

CONCLUSION(S)

The effect of mifepristone on endometrial steroid receptors was consistent with functional inhibition of progesterone. The findings warrant further investigation of this regimen as a strategy to reduce frequent bleeding.

Vaginal bleeding disturbances and implantable contraceptives

Implantable contraceptives allow safe and effective fertility regulation for up to 5 years. Currently available devices release low doses of progestogens. Disruption of vaginal bleeding patterns is almost inevitable, particularly during the initial months of use. Irregular and prolonged bleeding as well as amenorrhea are common. Irregular bleeding is unpopular with most women and unacceptable to some. This review describes the vaginal bleeding disturbances induced by modern implantable contraceptives and discusses the implications of these in terms of method use and discontinuations. The cause of the irregular bleeding is not fully understood, but recent evidence suggests that an increase in endometrial vascular fragility might precipitate vessel breakdown and, hence, breakthrough bleeding. This review discusses this evidence and outline the possible mechanisms underlying breakthrough bleeding associated with implantable contraceptives. In addition, therapies for bleeding disturbances are described and their efficacy reviewed.

Endometrial effects of etonogestrel (Implanon) contraceptive implant

The subdermal contraceptive implant etonogestrel (Implanon; NV Organon International, Oss, The Netherlands) exerts complex effects on the endometrium. These include direct effects on the endometrium through endometrial progestin target sites, and indirect effects through suppression of the hypothalamic-pituitary-ovarian axis. The resulting effects are categorized by alterations in endometrial histology, endometrial thickness, dysmenorrhoea and menstrual bleeding pattern. The exact mechanism of action of progestins on the endometrium has not been determined. The contraceptive effect in Implanon users is mainly due to inhibition of ovulation. Current research is concentrating on the potential of the progestin implant to modify endometrial vascular, angiogenic, steroid receptor and proto-oncogene function. These processes may be involved in the causation of progestin-induced breakthrough bleeding.

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.

Once a month administration of mifepristone improves bleeding patterns in women using subdermal contraceptive implants releasing levonorgestrel

It has been suggested that the administration of an anti-progesterone might improve bleeding patterns in women with irregular bleeding while using low-dose progestin-only contraception. We report the findings of a double-blind, randomized, placebo-controlled trial of mifepristone 50 mg taken once every 4 weeks in 100 Chinese women (50 subjects and 50 controls) complaining of frequent and irregular bleeding while using a levonorgestrel-releasing subdermal contraceptive implant. In all women, regardless of treatment, the frequency of bleeding decreased significantly over 360 days of observation. Women recorded significantly shorter episodes of bleeding (P: < 0.0002) during mifepristone treatment than during the 90 days before treatment started. In contrast, the duration of bleeding episodes fell more gradually in placebo-treated controls. Women using mifepristone were more likely to find treatment acceptable than women receiving a placebo tablet (P: < 0.01). Despite concern that anti-progestogenic effects may jeopardize contraception, there were no pregnancies. This approach may offer a useful strategy to improve continuation rates by alleviating unwanted side-effects until bleeding patterns improve spontaneously with time.