Concentration of plasminogen activators and inhibitor in the human endometrium at different phases of the menstrual cycle

The Plasminogen Activator System, Glucocorticoid, and Mineralocorticoid Receptors in the Primate Endometrium During Artificial Menstrual Cycles

As a key mechanism in fibrinolysis and tissue remodeling, the plasminogen activator system has been suggested in the process of endometrial shedding and tissue remodeling. Previous studies have explored the role of estrogen, progesterone, and androgen receptors as well as elements of the renin-angiotensin-aldosterone system in shaping the morphology of the endometrium. This study investigates the distribution and concentrations of the mineralocorticoid receptor, glucocorticoid receptor, tissue plasminogen activator, urokinase plasminogen activator, and plasminogen activator inhibitor-1 within the endometrial stroma, glandular, and endothelial cells of the primate endometrium during artificial menstrual cycles. Our immunohistochemistry quantification shows mineralocorticoid and glucocorticoid receptors are ubiquitously distributed within the macaque endometrium with their patterns of expression following similar fluctuations to urokinase and tissue plasminogen activators particularly within the endometrial vasculature. These proteins are present in endometrial vasculature in high levels during the proliferative phase, decreasing levels during the secretory phase followed by rising levels in the menstrual phase. These similarities could suggest overlapping pathways and interactions between the plasminogen activator system and the steroid receptors within the endometrium. Given the anti-inflammatory properties of glucocorticoids and the role of plasminogen activators in endometrial breakdown, the glucocorticoid receptor may be contributing to stabilizing the endometrium by regulating plasminogen activators during the proliferative phase and menstruation. Furthermore, given the anti-mineralocorticoid properties of certain anti-androgenic progestins and their reduced unscheduled uterine bleeding patterns, the mineralocorticoid receptor may be involved in unscheduled endometrial bleeding.

A complex of novel protease inhibitor, ovostatin homolog, with its cognate proteases in immature mice uterine luminal fluid

A predominant gelatinolytic enzyme with approximately 26 kDa was observed in gelatin zymogram of immature mice uterine luminal fluid (ULF). Size exclusion analysis revealed that the native size of this enzyme was close to that of human α₂-macroglobulin (α₂-MG), a 725 kDa protein. This large protease was isolated by a series of chromatographic steps on the Sephacryl S-400 and DEAE-Sepharose columns. The results from gelatin zymography and SDS-PAGE analysis supported that this large protease consists of gelatinolytic enzyme and a 360 kDa protein. Through tandem mass spectrometry analysis followed by MASCOT database search, the 360 kDa protein was identified as ovostatin homolog (accession: NP_001001179.2) assigned as a homolog of chicken ovostatin, a protease inhibitor. The co-fractionation analysis by gel filtration and mouse ovostatin homolog (mOH) co-immunoprecipitation experiments demonstrated that the mOH formed a complex with three gelatinolytic enzymes in immature mice ULF. Substrate zymography analysis revealed that the mOH-associated gelatinolytic enzymes were suitable to digest type I collagen rather than type IV collagen. In addition, the refolded mOH-associated 26 kDa gelatinolytic enzyme displayed the type I collagen-digesting activity in the assay, but the other two enzymes did not have this function. RT-PCR analysis showed that mOH gene was abundantly expressed in brain, spinal cord, lung, uterus, and in 17-day embryo. Taken together, our data suggest that mOH/cognate protease system may play a potential role in regulation of tissue remodeling and fetal development.

Serum estradiol levels in controlled ovarian stimulation directly affect the endometrium

Previous studies have shown that increasing estradiol concentrations had a toxic effect on the embryo and were deleterious to embryo adhesion. In this study, we evaluated the physiological impact of estradiol concentrations on endometrial cells to reveal that serum estradiol levels probably targeted the endometrium in controlled ovarian hyperstimulation (COH) protocols. An attachment model of human choriocarcinoma (JAr) cell spheroids to receptive-phase endometrial epithelial cells and Ishikawa cells treated with different estradiol (10^-9 M or 10^-7 M) concentrations was developed. Differentially expressed protein profiling of the Ishikawa cells was performed by proteomic analysis. Estradiol at 10^-7 M demonstrated a high attachment rate of JAr spheroids to the endometrial cell monolayers. Using iTRAQ coupled with LC-MS/MS, we identified 45 differentially expressed proteins containing 43 significantly upregulated and 2 downregulated proteins in Ishikawa cells treated with 10^-7 M estradiol. Differential expression of C₃, plasminogen and kininogen-1 by Western blot confirmed the proteomic results. C₃, plasminogen and kininogen-1 localization in human receptive endometrial luminal epithelium highlighted the key proteins as possible targets for endometrial receptivity and interception. Ingenuity pathway analysis of differentially expressed proteins exhibited a variety of signaling pathways, including LXR/RXR activation pathway and acute-phase response signaling and upstream regulators (TNF, IL6, Hmgn3 and miR-140-3p) associated with endometrial receptivity. The observed estrogenic effect on differential proteome dynamics in Ishikawa cells indicates that the human endometrium is the probable target for serum estradiol levels in COH cycles. The findings are also important for future functional studies with the identified proteins that may influence embryo implantation.

Endometrial haemostasis and menstruation

Under normal physiological circumstances menstruation is a highly regulated, complex process that is under strict hormonal control. During normal menstruation, progesterone withdrawal initiates menstruation. The cessation of menstrual bleeding is achieved by endometrial haemostasis via platelet aggregation, fibrin deposition and thrombus formation. Local endocrine, immunological and haemostatic factors interact at a molecular level to control endometrial haemostasis. Tissue factor and thrombin play a key role locally in the cessation of menstrual bleeding through instigation of the coagulation factors. On the other hand, fibrinolysis prevents clot organisation within the uterine cavity while plasminogen activator inhibitors (PAI) and thrombin-activatable fibrinolysis inhibitors control plasminogen activators and plasmin activity. Abnormalities of uterine bleeding can result from imbalance of the haemostatic factors. The most common abnormality of uterine bleeding is heavy menstrual bleeding (HMB). Modern research has shown that an undiagnosed bleeding disorder, in particular von Willebrand disease (VWD) and platelet function disorders, can be an underlying cause of HMB. This has led to a change in the approach to the management of HMB. While full haemostatic assessment is not required for all women presenting with HMB, menstrual score and bleeding score can help to discriminate women who are more likely to have a bleeding disorder and benefit from laboratory haemostatic evaluation. Haemostatic agents (tranexamic acid and DDAVP) enhance systemic and endometrial haemostasis and are effective in reducing menstrual blood loss in women with or without bleeding disorders. Further research is required to enhance our understanding of the complex interactions of haemostatic factors in general, and specifically within the endometrium. This will lead to the development of more targeted interventions for the management of abnormal uterine bleeding in the future.

The endocrine and paracrine control of menstruation

During the reproductive life, the human endometrium undergoes cycles of substantial remodeling including, at menstruation, a massive but delimited tissue breakdown immediately followed by scarless repair. The present review aims at summarizing the current knowledge on the endocrine and paracrine control of menstruation in the light of recent observations that undermine obsolete dogmas. Menstruation can be globally considered as a response to falling progesterone concentration. However, tissue breakdown is heterogeneous and tightly controlled in space and time by a complex network of regulators and effectors, including cytokines, chemokines, proteases and various components of an inflammatory response. Moreover, menstruation must be regarded as part of a complex and integrated mechanism of tissue remodeling including features that precede and follow tissue lysis, i.e. decidualization and immediate post-menstrual regeneration. The understanding of the regulation of menstruation is of major basic and clinical interest. Indeed, these mechanisms largely overlap with those controlling other histopathological occurrences of tissue remodeling, such as development and cancer, and inappropriate control of menstrual features is a major potential cause of two frequent endometrial pathologies (i.e. abnormal uterine bleeding and endometriosis).

SERPINE2, an inhibitor of plasminogen activators, is highly expressed in the human endometrium during the secretory phase

BACKGROUND

SERPINE2, also known as protease nexin-1, belongs to the serine protease inhibitor (SERPIN) superfamily. It is one of the potent SERPINs that modulates the activity of plasminogen activators (PAs). PAs and their SERPIN inhibitors, such as SERPINB2 and SERPINE1, were expressed in the human endometrium and were implicated in implantation. However, expression data about SERPINE2 in the human endometrium is still unknown. Thus, we conducted an investigation to reveal the spatiotemporal and cellular expression of SERPINE2 in the human uterus during the menstrual cycle.

METHODS

Seven patients who underwent a hysterectomy and samples of 120 archived patients' endometrial curettage or parts of the uterus that were formalin-fixed and embedded in paraffin. Western blotting was performed to evaluate the specificity and sensitivity of the antibody. Immunohistochemistry was conducted to localize the SERPINE2 expression site. Quantitative analysis was conducted to evaluate expression levels of SERPINE2 in various sub-phases of the menstrual cycle.

RESULTS

The SERPINE2 protein was primarily detected in the uterine fluid during the mid- and late-secretory phases of the menstrual cycle. It was predominantly expressed in the luminal and glandular epithelium, less in the myometrium, and only dispersedly in certain stromal cells throughout the menstrual cycle. A quantitative analysis of expression levels of SERPINE2 in the glandular epithelium revealed that it was highly expressed in the endometrium during the secretory phase compared to the proliferative phase.

CONCLUSIONS

The SERPINE2 protein is highly expressed in the endometrium during the secretory phase, indicating that it may participate in tissue remodeling involved in implantation.

Levonorgestrel-intrauterine system effects on hemostasis and menstrual blood loss in women seeking contraception

AIM

The purpose of the study is to determine the effects of levonorgestrel use on hemostasis, and menstrual blood loss over 24 months in a cohort of women seeking contraception.

METHODS

Data from 30 women (median age 36 years) were analyzed. Samplings at pre-insertion, 1 and 3 months for blood and additional endometrial aspirates at 2 and 6 months were performed. Systemic determination for hemoglobin, hematocrit, computerized thromboelastography, tissue-type plasminogen activator, urokinase-like plasminogen activator and receptor, plasminogen activator inhibitor-1/2, D-dimer and von Willebrand Factor was performed. In endometrial extracts, tissue-type plasminogen activator, urokinase-like plasminogen activator and receptor and plasminogen activator inhibitor-1/2 were assayed. The Menstrual Blood Loss Pictorial Chart Score for measurement of menstrual blood loss was carried out for 24 months.

RESULTS

There were no significant changes in systemic hemostasis within 3 months of device use. In the endometrium, there was a significant increase in tissue-type plasminogen activator antigen, plasminogen activator inhibitor-1/2 and urokinase-like plasminogen activator receptor levels from pre-insertion state, with the highest level seen by 6 months. Amenorrhea was seen in 20% of women by 6 months and 50% by 24 months.

CONCLUSIONS

Enhanced expression of plasminogen activator inhibitor-1/2 in the presence of increased urokinase-like plasminogen activator receptor and tissue-type plasminogen activator antigen was seen in the endometrium. The effects on hemostasis appear to be localized in the endometrium. Systemic hemostasis was not duly affected and menstrual blood loss was reduced. No women in the study had a pregnancy or expulsion of the levonorgestrel-intrauterine system device in the 24 months of the study period.

Matrix metalloproteinases and their tissue inhibitors in endometrial remodelling and menstruation

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

Effect of Norgestomet Treatment on Plasminogen Activator Activity in the Cervical Mucus and the Endometrium in Dairy Cows

The aim of this study was to determine the effect of norgestomet treatment, in the absence or the presence of a functional corpus luteum (CL), on plasminogen activators activity (PAA) in the cervical mucus and the endometrium in dairy cows. Eleven days after oestrus (Day 0 = oestrus), 38 cows were randomly assigned to one untreated control group (n = 9) and three treatment groups (S(1), S(2) and S(3)). Animals of S(1) group (n = 9) received an implantation of norgestomet on the outer surface of the ear for 8 days, simultaneous injection of oestradiol valerate 5 mg and norgestomet 3 mg, i.m., and on Day 19 an injection of ECG 500 IU, i.m. Animals of S(2) group (n = 11) received the treatment of S(1) group, plus an administration of PGF(2)alpha on Day 10 for the regression of CL. Animals of S(3) group received the treatment of S(2) group, plus two additional norgestomet implants inserted on Day 16 for 36 h. Both types of plasminogen activators [the tissue-type (t-PA) and the urokinase-type (u-PA)] were detected in the cervical mucus and the endometrium of the cows. Plasminogen activators activity in the cervical mucus was higher in control group than in S(1), S(2) and S(3) groups (P < 0.001). In contrast, endometrial PAA did not differ among groups (P > 0.05). Oestradiol-17beta concentrations on Day 21 were higher in S(2) group than in control group (P < 0.01) and S(3) group (P < 0.05). Progesterone concentrations did not differ among groups (P > 0.05). Oestradiol-17beta concentrations could positively affect cervical mucus PAA in control group (P < 0.1), but not in other groups (P > 0.05). These findings suggest that control of estrous cycle by norgestomet administration, in dairy cows, exerts a suppressive effect on plasminogen activators synthesis and/or secretion in the cervical mucus, regardless of the absence or the presence of the CL. On the contrary, endometrial PAA is not affected by norgestomet treatment.

Testosterone upregulation of tissue type plasminogen activator expression in Sertoli cells : tPA expression in Sertoli cells

Our previous studies have demonstrated that tissue type plasminogen activator (tPA) might be involved in matrix degradation of blood-testis barrier in rat. In this study, we have further investigated the effect of testosterone (T) on tPA production in rat Sertoli cells. Our results showed that Sertoli cells isolated from rat testes at various ages in vitro secreted tPA in an age-dependent manner. The tPA activity was detected on day 20 after birth, and reached maximum on day 60. The Sertoli cells isolated from the testes on day 20 were then cultured in the presence or absence of testosterone, FSH, and forskolin, the tPA activities were upregulated by T, FSH and forskolin. Addition of H89 or U0126, both inhibited the testosterone-, FSH-, and forskolin-induced tPA expression. It is suggested that FSH- and testosterone-stimulated tPA expression in Sertoli cells may be via PKA and ERK signal transduction. Furthermore, we have observed that testosterone stimulated tPA secretion at all the stages of spermatogenesis (II-VI, VII-VIII, IX-XII and XIII-I), the highest stimulation of tPA activity was observed at stages VII-VIII. This study further suggests that testosterone-induced tPA activity in the Sertoli cells might be related to the function of blood-testis barrier opening and/or closing.

The effect of levonorgestrel-releasing intrauterine system use on menstrual blood loss and the hemostatic, fibrinolytic/inhibitor systems in women with menorrhagia

BACKGROUND

Menorrhagia is known to be associated with uterine fibroids, adenomyosis, pelvic infections, endometrial polyps and clotting defects. A viable alternative therapy to hysterectomy should alleviate heavy menstrual blood flow and consequently improve the quality-of-life measures in women presenting with menorrhagia. The levonorgestrel-releasing intrauterine system (LNG-IUS) ranks higher than medical treatments in terms of efficacy, comparable improvements in quality of life and psychological well-being.

OBJECTIVE

The purpose of the study was to determine the effects of 6 months of LNG-IUS use on menstrual blood loss and the hemostatic, fibrinolytic/inhibitor systems in blood and the endometrium in women with menorrhagia with known pathologic causes.

PATIENTS AND METHODS

Samples from 41 women were analyzed. Hemoglobin, hematocrit, thrombelastography, tissue-type plasminogen activator (t-PA), urokinase plasminogen activator (u-PA), u-PA receptor (u-PAR), plasminogen activator inhibitor-1/2 (PAI-1/2), D-dimer and von Willebrand factor (VWF) were determined, and t-PA, u-PA and PAI-1/2 were also determined in endometrial tissue extracts.

RESULTS

Menorrhagia was reduced in 89% of women by 3 months; by 6 months all women had no menorrhagia, and 39% of women had become amenorrhoeic. Hemoglobin and hematocrit levels showed improvement, and reached normal reference levels by 6 months. There were no systemic changes in the fibrinolytic/inhibitor systems and VWF, except for a decreased u-PAR level. However, in the endometrium, significant elevations in PAI-1/2 together with u-PAR levels were seen at 6 months.

CONCLUSIONS

The slow levonorgestrel-release intrauterine device use results in high expression of fibrinolytic inhibitors (PAI-1/2) and upregulated u-PAR expression in the endometrium. Systemic hemostasis was not significantly altered. The study demonstrated that LNG-IUS is highly effective in the treatment of menorrhagia with known pathologic causes.

Hemostatic status and fibrinolytic response potential at different phases of the menstrual cycle

Coagulation and fibrinolytic variables including platelet function and endogenous fibrinolytic response were determined in 30 normal healthy women volunteers not on any known medication during the period of study. They were between 18 years and 38 years old and had normal menstrual cycles of between 28 days and 30 days. Blood samples were obtained within one menstrual cycle and after having fasted overnight within days 1 to 3 (menstruation), 5 to 9 (follicular), 10 to 14 (mid-cycle), and 21 to 26 (luteal) of the menstrual cycle. Analysis of variance (ANOVA) showed no significant differences in the hemostatic parameters studied between the phases of the menstrual cycle except for a reduced D-dimer level at midcycle. Significant fibrinolytic response was seen after venous occlusion but they were not significantly different between the phases of the menstrual cycle. The women were then divided into either normal weight (n=22) or overweight (n=8) according to World Health Organization (WHO) classification and the data reanalyzed. Elevated tissue plasminogen activator antigen and plasminogen activator inhibitor-1 levels except at menstruation and total protein S except at follicular phase were observed in overweight women together with increased plasminogen level only at luteal phase. Significant endogenous fibrinolytic response seen during the menstrual cycle was not different between normal and overweight women. The study demonstrated that systemic coagulation, fibrinolysis, and platelet function were probably not influenced by natural hormonal changes occurring during the menstrual cycle except for an associated reduced fibrinolytic state at mid-cycle. The hemostatic system in this small group of healthy overweight women studied appeared to be physiologically compromised.

Involvement of the plasminogen activation system in cow endometritis

The objectives of this study were to investigate the: (a) presence and activity of components of the "plasminogen activators/plasmin" system in dairy cows with or without endometritis; (b) variations in enzyme activity according to the degree of endometritis; and (c) associations between these enzymes and changes in endometrial histology after intrauterine antibiotic treatment. Endometrial biopsies were collected from anestrus (no palpable ovarian structures and milk progesterone <1 ng/ml) Holstein cows, 30-40 days postpartum. On the basis of a vaginoscopic examination, rectal palpation of the cervix and uterus, and endometrial histology, there were 92 cows with endometritis and 20 cows without endometritis. After biopsy collection, each cow was given an intrauterine infusion of 1.5x10(6) IU of procaine penicillin G. In cows with endometritis, genital tract examinations and biopsies were repeated 2 weeks later. Both plasminogen activators (PAs), tissue type (t-PA) and urokinase (u-PA), were immunologically identified in all uterine biopsies. Plasminogen activator activity (PAA) increased, whereas plasminogen activator inhibition (PAI) and plasmin inhibition (PI) decreased in proportion to the degree of inflammation. Two weeks after intrauterine treatment, PAA had decreased significantly in all cows that had reduced severity of endometrial inflammation and had increased significantly in all cows with increased severity of inflammation. The change in the degree of inflammation depended upon plasminogen activator activity; cows with higher PAA were more likely to improve. In conclusion, there was evidence for a role of the plasminogen activation proteolytic system in bovine endometritis.

Fibrinolytic factors in endometriotic tissue, endometrium, peritoneal fluid, and plasma from women with endometriosis and in endometrium and peritoneal fluid from healthy women

OBJECTIVE

To determine whether there is a difference in fibrinolytic compounds in endometriotic tissue, endometrium, peritoneal fluid (PF), and plasma from women with endometriosis and in endometrium and PF from healthy women.

DESIGN

Prospective study.

SETTING

Two university clinics.

PATIENT(S)

Regularly menstruating women with and without endometriosis.

INTERVENTION(S)

Tissue samples, PF, and blood were collected at surgery performed for clinical reasons.

MAIN OUTCOME MEASURE(S)

The antigen concentrations of plasminogen activators and plasminogen activator inhibitors (PAls) in tissue homogenates, PF, and plasma were assayed by ELISA.

RESULT(S)

The concentrations of urokinase plasminogen activator (u-PA) and PAI-1 were higher in endometrium from women with endometriosis than in endometrium from controls and even higher in endometriotic tissue than in endometrium from both groups. In PF, the concentration of PAI-2 was higher in women with endometriosis than in controls.

CONCLUSION(S)

The high concentrations of u-PA and PAI-1 in endometrium from women with endometriosis might facilitate implantation of endometrial cells and the high concentration in endometriotic tissue might contribute to their invasive growth. The inflammatory reaction may contribute to the high concentration of PAI-2.