The release of PGF2 alpha and PGE2 from separated cells of human endometrium and decidua

Basolateral secretions of human endometrial epithelial organoids impact stromal cell decidualization

Uterine glands and, by inference, their secretions impact uterine receptivity, blastocyst implantation, stromal cell decidualization, and placental development. Changes in gland function across the menstrual cycle are primarily governed by the steroid hormones estrogen (E2) and progesterone (P4) but can also be influenced by extrinsic factors from the stroma. Using a human endometrial epithelial organoid system, transcriptome and proteome analyses identified distinct responses of the organoids to steroid hormones and prostaglandin E2 (PGE2). Notably, P4 and PGE2 modulated the basolateral secretion of organoid proteins, particularly cystatin C (CST3), serpin family A member 3 (SERPINA3), and stanniocalcin 1 (STC1). CST3, but not SERPINA3 or STC1, attenuated the in vitro stromal decidualization response to steroid hormones and PGE2. These findings provide evidence that uterine gland-derived factors impact stromal cell decidualization, which has implications for pregnancy establishment and fertility in women.

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.

Selective Estrogen-Receptor Modulators and Aromatase Inhibitors: Promising New Medical Therapies for Endometriosis?

Endometriosis is an estrogen-dependent disease and estrogen-related pathways are imbalanced in women with endometriosis. One of the key enzymes in estrogen synthesis is aromatase. Inhibiting this pathway at several points is a promising idea for the treatment of endometriosis. The third generation of aromatase inhibitors is becoming more potent in efficacy, with fewer side effects than previous generations, but cotreatment with other hormones is needed to inhibit ovarian stimulation. Other components that promote estrogen synthesis such as COX-2 can also be potentially targeted. Selective estrogen-receptor modulators could also be interesting in view of their tissue-specific effect. However, all these new drugs are still in an early phase of development. At present, it is too early to conclude that aromatase inhibitors, COX-2 inhibitors or selective estrogen-receptor modulators really present any added value compared with the existing drugs that can be used to achieve hormonal suppression in the medical treatment of endometriosis.

The Prostaglandin F Synthase Activity of the Human Aldose Reductase AKR1B1 Brings New Lenses to Look at Pathologic Conditions

Prostaglandins are important regulators of female reproductive functions to which aldose reductases exhibiting hydroxysteroid dehydrogenase activity also contribute. Our work on the regulation of reproductive function by prostaglandins (PGs), lead us to the discovery that AKR1B5 and later AKR1B1were highly efficient and physiologically relevant PGF synthases. PGE2 and PGF2α are the main prostanoids produced in the human endometrium and proper balance in their relative production is important for normal menstruation and optimal fertility. Recent evidence suggests that PGE2/EP2 and PGF2α/FP may constitute a functional dyad with physiological relevance comparable to the prostacyclin-thromboxane dyad in the vascular system. We have recently reported that AKR1B1 was expressed and modulated in association with PGF2α production in response to IL-1β in the human endometrium. In the present study, we show that the human AKR1B1 (gene ID: 231) also known as ALDR1 or ALR2 is a functional PGF2α synthase in different models of living cells and tissues. Using human endometrial cells, prostate, and vascular smooth muscle cells, cardiomyocytes and endothelial cells we demonstrate that IL-1β is able to up regulate COX-2 and AKR1B1 proteins as well as PGF2α production under normal glucose concentrations. We show that the promoter activity of AKR1B1 gene is increased by IL-1β particularly around the multiple stress response region containing two putative antioxidant response elements adjacent to TonE and AP1. We also show that AKR1B1 is able to regulate PGE2 production through PGF2α acting on its FP receptor and that aldose reductase inhibitors like alrestatin, Statil (ponalrestat), and EBPC exhibit distinct and characteristic inhibition of PGF2α production in different cell models. The PGF synthase activity of AKR1B1 represents a new and important target to regulate ischemic and inflammatory responses associated with several human pathologies.

Effects of Yiweining Recipe on expressions of metalloproteinase-2 and cyclooxygenase-2 mRNAs in ectopic endometrium of rats with endometriosis

OBJECTIVE

To explore the effects of Yiweining Recipe (YWNR), a compound Chinese herbal medicine, on expressions of metalloproteinase-2 (MMP-2) and cyclooxygenase-2 (COX-2) mRNAs in rats with endometriosis (EM).

METHODS

Operational self-transplantation was applied in establishing the rat models. Detection of MMP-2 and COX-2 mRNAs was conducted with hybridization in situ.

RESULTS

There were significant differences in the expressions of MMP-2 and COX-2 mRNAs between the untreated group and the high-dose YWNR-treated group. YWNR could reduce the expressions of MMP-2 and COX-2 mRNAs.

CONCLUSION

YWNR can treat EM through reducing the positive expressions of MMP-2 and COX-2 mRNAs.

Independent regulation of prostaglandins and monocyte chemoattractant protein-1 by interleukin-1β and hCG in human endometrial cells

BACKGROUND

Inflammatory mediators such as prostaglandins (PG), chemokines, cytokines and their interactions regulate reproductive functions. The relationship between PG and monocyte chemoattractant protein-1 (MCP-1) has not been elucidated in human endometrium. The presence of hCG receptors in the human endometrium suggests that this embryonic signal may exert a local function in this tissue. Our objectives were to investigate the possible association between PG and MCP-1 and to examine the role of hCG in interleukin-1beta (IL-1beta)-regulated PG and MCP-1 production in human endometrium.

METHODS

Primary cell cultures isolated from endometrial biopsies were used as an in vitro model. PG and MCP-1 levels were measured in the culture medium.

RESULTS

IL-1beta stimulates the production of both PG and MCP-1. Neither COX inhibitors nor direct addition of PG affects MCP-1 production. By contrast, MCP-1 is able to induce PGE2 and PGF2alpha in a concentration-dependent manner but it does not appear to contribute to the increase in PG accumulation following IL-1beta stimulation. hCG inhibits IL-1beta-induced PG level. However, hCG has no effect on either basal or IL-1beta-mediated MCP-1 level.

CONCLUSIONS

PG are not involved in the regulation of MCP-1 production in endometrial cells. hCG appears to play a local function in the endometrium.

The treatment with a COX-2 specific inhibitor is effective in the management of pain related to endometriosis

OBJECTIVE

To evaluate the efficacy and safety of a cyclooxygenase (COX)-2 specific inhibitors versus placebo in the treatment of endometriosis-associated pelvic pain.

STUDY DESIGN

A group of women (n = 28) with pelvic pain after conservative surgery for symptomatic endometriosis (Stage I and II) were enrolled at the Department of Pediatric, Obstetrics and Reproductive Medicine of University of Siena. A treatment with a COX-2 specific inhibitors (rofecoxib, 25mg per day) (n = 16) or placebo (n = 12) was given for 6 months. Pelvic pain quantification with a clinical evaluation, including Visual Analogue Scale (VAS) for pain, was performed before and up to 6 months after treatment.

RESULTS

A significant improvement of both pelvic pain and dyspareunia was observed after a 6 months persisting since the end of the treatment (P < 0.0001). The efficacy of rofecoxib was higher than placebo and no recurrence occurred, while in the placebo-treatment a 16% (2/12) occurred. No significant side effects have been found with the use of rofecoxib.

CONCLUSIONS

The use of COX-2 specific inhibitors was effective, safe and low cost therapy in the management of pelvic pain associated to endometriosis and might be also proposed in early stage of endometriosis.

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.

Cyclooxygenases and prostaglandin E synthases in the endometrium of the rhesus monkey during the menstrual cycle

Cyclooxygenase (COX), a rate-limiting enzyme that produces prostaglandins (PGs) from arachidonic acid, exists in two isoforms, COX-1 and COX-2. PGE2synthase (PGES) is a terminal prostanoid synthase and can enzymatically convert the cyclooxygenase product PGH2to PGE2, including two isoforms: microsomal PGES (mPGES) and cytosolic PGES (cPGES). cPGES is predominantly linked with COX-1 to promote the immediate response. mPGES is preferentially coupled with the inducible COX-2 to promote delayed PGE2generation. COX-2-deficient female mice are infertile with abnormalities in ovulation, fertilization, implantation and decidualization. The aim of this study was to examine immunohistochemically the expression pattern of COX-1, COX-2, mPGES and cPGES proteins in the endometrium of the rhesus monkey during the menstrual cycle. COX-1 immunostaining was mainly localized in the luminal epithelium and glandular epithelium near the lumen, and detected in all the stages during the menstrual cycle. COX-2 immunostaining was mainly localized in the luminal and glandular epithelium, and strongly shown during the mid-luteal phase (days 16 and 20) of the menstrual cycle. There was a strong cPGES immunostaining in the luminal and glandular epithelium on days 12, 16, 20 and 25 of the menstrual cycle. mPGES immunostaining was strongly detected in the glandular epithelium on days 20 and 25 of the menstrual cycle. These data suggest that the coupling of cPGES and COX-1 in the luminal epithelium may be responsible for the synthesis of PGE2in monkey endometrium, and the coupling of mPGES and COX-2 in the glandular epithelium may be of importance for preparing the receptive endometrium.

Oxytocin mRNA content in the endometrium of non-pregnant women

OBJECTIVE

To study oxytocin mRNA in the human endometrium at different phases of the menstrual cycle.

DESIGN

An exploratory study in non-pregnant women.

SETTING

The Department of Obstetrics and Gynecology, Lund University Hospital, Sweden.

PARTICIPANTS

Thirty-three women of fertile age undergoing hysterectomy or endometrial curettage on routine benign gynaecologic indications.

METHODS

Endometrial tissue was obtained throughout the menstrual cycle. The presence of oxytocin mRNA was investigated by in situ hybridisation and by real time PCR.

MAIN OUTCOME MEASURES

Oxytocin mRNA signalling intensity found by in situ hybridisation of tissue obtained at different times of the menstrual cycle. Relative amounts of oxytocin mRNA measured by real time PCR.

RESULTS

The signal for oxytocin mRNA obtained by in situ hybridisation was more pronounced in glandular epithelial cells than in stromal cells. Furthermore, it was most marked around mid-cycle. The expression of oxytocin mRNA was confirmed by real time PCR.

CONCLUSIONS

The results indicate that oxytocin may be synthesised in the endometrium of non-pregnant women, particularly in the glandular epithelial cells. Hormone released from these sources may have a paracrine action on the uterus. Oxytocin mRNA expression seems to be ovarian hormone dependent with the highest concentration around mid-cycle.

Stromal vascularization in the endometrium during adenomyosis

In adenomyosis, the two major frequent symptoms are hypermenorrhea and dysmenorrhea. The incidence of the former is said to be high, ranging from 36 to 70%. It has been found that vascular distribution of the endometrium in adenomyosis is diversely different from fertile patients without adenomyosis. For example, hysteroscopy revealed that approximately half of the patients have abnormal vascularization. In these patients, vascular distribution was generally irregular, and vessels were thick, dilated, and/or reticular in some patients. Moreover, morphometric analysis of the endometrium revealed that in the fertile women, the mean surface area, total surface area, and total number of capillaries, all increased significantly in the secretory phase compared to the proliferative phase. In contrast, the above parameters increased in the adenomyosis group in both the proliferative phase and secretory phase compared to the fertile women. In particular, the total surface area of capillaries per mm(2) markedly rose, by 11.6 times, compared to that of the proliferative phase in the fertile women. These findings suggest that regulatory factors involved in the vascular proliferation are diversely exaggerated, and that the abnormal vascularization of the endometrium is closely related with hypermenorrhea.

Progesterone as an immunomodulatory molecule

Increased progesterone sensitivity of pregnancy lymphocytes is due to activation-induced appearance of progesterone binding sites in the lymphocytes. Following recognition of fetally derived antigens gamma/delta TCR+ cells develop progesterone receptors. Progesterone binding results in the synthesis of a mediator protein named the progesterone-induced blocking factor (PIBF). PIBF by acting on the phospholipase A2 enzyme interferes with arachidonic acid metabolism, induces a Th2 biased immune response, and by controlling NK activity exerts an anti-abortive effect.

Distribution of cyclooxygenase-2 in eutopic and ectopic endometrium in endometriosis and adenomyosis

The objective of this study was to determine the distribution of cyclooxygenase-2 (COX-2) in eutopic and ectopic endometria in endometriosis and adenomyosis. The subjects were 35 patients with endometriosis diagnosed by laparoscopy, 33 patients with histologically confirmed adenomyosis and 50 female controls with normal fecundity. Expression of COX-2 was immunohistochemically investigated in tissues from eutopic endometrium and myometrium and ectopic endometrium of the wall of ovarian chocolate cysts using polyclonal antibody. Surface epithelial cells, endometrial glandular epithelial cells or stromal cells were assessed. Cells were semi-quantitatively assessed on a scale of 1 to 5 using a nomogram created from positive cell count and the degree of staining. COX-2 expression in surface and glandular epithelia of the control group varied markedly during the menstrual cycle. It was lowest in the early proliferative phase and gradually increased thereafter. It remained high throughout the secretory phase. However, in patients with endometriosis, expression of COX-2 in glandular epithelium was higher than that in the control group, though it varied throughout the menstrual cycle. On the other hand, there was no variation in expression of COX-2 in the adenomyosis group during the menstrual cycle, and it was lower than that in the endometriosis group in all phases. Pronounced COX-2 expression was observed in glandular cells from ectopic endometrial tissue of ovarian chocolate cyst walls in all cases regardless of the menstrual phase. In summary, increased COX-2 expression in eutopic and ectopic endometria was believed to be strongly correlated with pathological abnormalities in these disorders.

Expression of cyclooxygenase 2 by prostaglandin E(2) in human endometrial adenocarcinoma cell line HEC-1B

The regulation of expression of cyclooxygenase 2 (COX-2) was investigated by treatment with PGE(2) in human endometrial adenocarcinoma cell line HEC-1B. One microM PGE(2) could stimulate the expression of COX-2 approximately twofold in this cell line. The same concentration of PGE(2) also stimulated activation of mitogen-activated protein kinase (MAP kinase) and protein kinase B (PKB). PGE(2)-induced MAP kinase activation was sensitive to a MAP kinase kinase (MEK) inhibitor, PD098059, and a protein kinase A inhibitor, H-89. PD098059 and H-89 also partially inhibited the expression of COX-2 stimulated by PGE(2). PGE(2) could stimulate the activation of PKB, which was sensitive to phosphatidylinositol-3-OH kinase (PI3K) inhibitor, wortmannin. Whereas wortmannin alone partially inhibited the expression of COX-2, a combination of wortmannin and PD098059 totally inhibited PGE(2)-mediated COX-2 expression. These results suggest that MAP kinase and PI3K pathways are stimulated with PGE(2), and that both of these pathways are involved in the expression of COX-2. In addition, they also suggest that protein kinase A remains upstream of PGE(2)-induced activation of MAP kinase in HEC-1B cells.

Cyclooxygenase is involved in the effects of progesterone-induced blocking factor on the production of interleukin 12

OBJECTIVE

Immunologic effects of progesterone are mediated by the progesterone-induced blocking factor. Progesterone-induced blocking factor inhibits natural killer cytotoxic activity and arachidonic acid release from mononuclear cells. The relationship between increased prostaglandin synthesis and increased cytotoxic activity of the lymphocytes is still unclear; therefore we investigated the effect of progesterone-induced blocking factor-neutralizing antibody, as well as simultaneous indomethacin treatment, on interleukin 12 production.

STUDY DESIGN

Pregnancy lymphocytes were treated with anti-progesterone-induced blocking factor antibody or lipopolysaccharide as a positive control in the presence or absence of indomethacin. Interleukin 12 production by peripheral blood mononuclear cells was detected by immunocytochemical examination. The 2-tailed Student t test was used for statistical evaluation.

RESULTS

Neutralization of progesterone-induced blocking factor, as well as lipopolysaccharide treatment, resulted in an increased expression of interleukin 12 that was corrected by simultaneous indomethacin treatment.

CONCLUSION

Progesterone-induced blocking factor reduces the expression of interleukin 12 via the inhibition of arachidonic acid metabolism. This results in lowered cytotoxic natural killer activity, which favors a normal pregnancy outcome.

Interleukin-1 receptor antagonist blocks interleukin-1-induced expression of cyclooxygenase-2 in endometrium

OBJECTIVE

Our purpose was to test the hypothesis that the interleukin-1 receptor antagonist can inhibit interleukin-1-induced prostaglandin production and de novo expression of the inducible cyclooxygenase-2 isoform in a human endometrial epithelial cell line.

STUDY DESIGN

A continuous line of human endometrial epithelial cells was established from a hysterectomy specimen from a nonmalignant uterus. Cells were maintained as a monolayer culture in medium 199 supplemented with 10% fetal bovine serum and 50 micrograms/ml gentamicin. Cultures were treated with cytokines (interleukin-1 alpha or interleukin-1 beta, interleukin-1 receptor antagonist, or tumor necrosis factor-alpha), and media were collected for analysis of prostaglandin E2 and prostaglandin F2 alpha) by radioimmunoassay, whereas cells were harvested for ribonucleic acid and protein extractions and subsequent Northern blot or Western blot analyses, respectively.

RESULTS

When endometrial cells were incubated with interleukin-1 alpha or interleukin-1 beta, each cytokine was shown to stimulate the production of prostaglandin E2 and prostaglandin F2 alpha in a time- and dose-dependent fashion, with interleukin-1 alpha being far more potent than interleukin-1 beta. Interleukin-1 receptor antagonist inhibited interleukin-1 alpha- and interleukin-1 beta-induced prostaglandin formation, with 50% inhibitory concentration values of 30 ng/ml for prostaglandin E2 and 90 ng/ml for prostaglandin F2 alpha. When Northern blots of interleukin-1 alpha-treated cells were probed with a complementary deoxyribonucleic acid fragment specific for either cyclooxygenase-1 or cyclooxygenase-2, rapid de novo induction of cyclooxygenase-2 messenger ribonucleic acid was observed; however, cyclooxygenase-1 expression was constant regardless of interleukin-1 alpha concentration or incubation time. Coincubation of cells with interleukin-1 alpha (10 ng/ml) and cycloheximide caused superinduction of cyclooxygenase-2 messenger ribonucleic acid but had no effect on the expression of cyclooxygenase-1 messenger ribonucleic acid. Actinomycin D completely abolished interleukin-1 alpha-induced cyclooxygenase-2 messenger ribonucleic acid expression, suggesting that the cytokine caused transcriptional activation of the cyclooxygenase-2 gene. Experiments were conducted to examine whether interleukin-1 receptor antagonist could suppress interleukin-1-induced cyclooxygenase-2 expression. Cells were preincubated for 30 minutes with interleukin-1 receptor antagonist and then challenged with interleukin-1 alpha. Northern and Western analyses revealed that interleukin-1 receptor antagonist blocked interleukin-1 alpha-induced expression of cyclooxygenase-2 messenger ribonucleic acid transcripts and the subsequent appearance of cyclooxygenase-2 protein. Interleukin-1 receptor antagonist had no effect on the constitutive expression of cyclooxygenase-1 messenger ribonucleic acid and protein. Interleukin-1 receptor antagonist failed to alter prostaglandin E2 formation in response to tumor necrosis factor-alpha, indicating that the antagonist is specific for interleukin-1 family cytokines. Finally, interleukin-1 receptor antagonist acted as a partial agonist in some experiments in that relatively high concentrations (> 100 ng/ml) caused a modest increase in prostaglandin E2 and F2 alpha production.

CONCLUSIONS

These data indicate that interleukin-1 receptor antagonist is a potent inhibitor of interleukin-1-induced arachidonic acid metabolism and could possibly serve as an endogenous or exogenous modulator of interleukin-1 action in the endometrial epithelium.

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.

Interleukin-1 beta induces cyclooxygenase-2 in cultured human decidual cells

PROBLEM

The purpose of this study was to examine the hypothesis that interleukin-1 beta (IL-1 beta)-elicited increases in decidual prostaglandin E2 and F2 alpha (PGE2 and PGF2 alpha) biosynthesis are due to the de novo expression of the inducible isoform of cyclooxygenase (i.e., COX-2).

METHOD

Primary human decidual cell cultures were established from term placentas delivered by cesarean section. After 8 days in vitro, when the cultures secreted immunoreactive prolactin, the cells were incubated for 24 h in serum-free medium, and then challenged with IL-1 beta from 1 to 48 h. PGE2 and PGF2 alpha content in the media were measured by specific radioimmunoassays.

RESULTS

IL-1 beta stimulated a time-dependent enhancement in PGE2 and PGF2 alpha production, with PGF2 alpha synthesis predominating over PGE2. IL-1 beta also induced a dose-dependent increase in the output of both arachidonic acid metabolites. When Northern blots of IL-1 beta-treated and control cells were probed with cDNAs encoding either COX-1 or COX-2 isoforms or an oligonucleotide probe encoding a portion of the human beta-actin, we detected a time- and dose-dependent increase in the steady-state levels of COX-2, but not COX-1 or beta-actin mRNA transcripts. Moreover, the expression of COX-2 mRNA in IL-1 beta-stimulated cells was superinduced by preincubation with cycloheximide, but completely abolished by actinomycin D.

CONCLUSIONS

Taken together, the data suggest that COX-2 mRNA expression is largely responsible for the robust increase in PG formation seen in IL-1 beta-treated decidual cells.

Functions of macrophages in human decidual tissue in early pregnancy

PROBLEM

Roles of decidual macrophages (DMs) in the maintenance of early pregnancy was determined by comparing three of their functions, antigen presentation, immunoregulation, and lymphokine production, with those of peripheral monocytes (PMos) isolated from the same subjects.

METHOD

The antigen-presenting capacity of DMs was examined by the one-way mixed lymphocyte reaction (MLR) in which accessory cell-depleted mononuclear cells isolated from pregnant women were used as responders. The effect of DMs on cellular immunity was investigated by inhibition tests of either one-way MLR or phytohemagglutinin stimulation. The production of interleukin-1 (IL-1) and prostaglandin E2 (PGE2) by DMs following lipopolysaccharide stimulation was examined.

RESULTS

Addition of increasing concentrations of DMs to the culture resulted in a concentration-dependent proliferative response, as well as with PMos. In both assays, a stronger suppression was observed in the presence of DMs from normal pregnant women compared with PMos from the same subjects. DMs were found to secrete significantly lower levels of IL-1 alpha and IL-1 beta than PMos. No difference in PGE2 production was observed between DMs and PMos.

CONCLUSIONS

These findings suggest that DMs present in human early decidual tissue have a capacity for allo-antigen presentation, a higher suppressive activity, and a lower capacity to produce IL-1 than their peripheral counterparts.

Effect of prostaglandin synthesis inhibitors on spontaneous and endotoxin-induced abortion in mice

The putative role of prostaglandin E2 (PGE2) in suppressing rejection of the 'fetal allograft' (resorption) in C3H/HeJ and CBA/J allopregnant mice was tested by administration of the prostaglandin synthesis inhibitors indomethacin (INDO) and acetylsalicylic acid (ASA). When the resorption rate was low, INDO fed at a dose of 15 micrograms/ml in drinking water after implantation had a slight augmenting effect when the endogenous resorption rate was < 30%, but had no effect when the endogenous rate was higher or when bacterial lipopolysaccharide (LPS) was given. ASA fed at 50 micrograms/ml had no augmenting effect and did not increase sensitivity to the abortogen LPS in either CBA/J (LPS sensitive) or C3H/HeJ (LPS resistant) mice. Both INDO and ASA fed to CBA/J mice significantly reduced endogenous PGE2 extractable from the uteri of hormonally pseudopregnant mice after deciduoma induction. Feeding INDO at doses up to 30 micrograms/ml from day 2.5 of pregnancy impaired but failed to completely block implantation in CBA/J mice, and with daily administration, some of the mice became sick: all of the implants in sick mice resorbed. INDO at doses of 150-200 micrograms per day known to inhibit implantation in vivo by sufficiently blocking PGE2 synthesis, was injected on one or more days beginning after the time of implantation. This failed to cause abortion in CBA/J mice and although some mice became ill, provided this happened after day 8.5 of pregnancy when sensitivity to the abortogenic effects of injected LPS decreased substantially in these mice, all implants in the sick mice were 'healthy' (i.e. non-resorbing). We were unable to increase the rate of resorption in syngeneically pregnant CD1 mice above 13% with 15 ml INDO in drinking water. Our data do not support the view that PGE2 represents an important intrauterine suppressor molecular blocking the processes mediating embryo death at the time of abortion. Spontaneous abortion in DBA/2-mated CBA/J mice appears to be determined by the level of bacterial LPS (endotoxin) and treatment with antibiotics or intralipid (which enhances endotoxin clearance), reduces the abortion rate. A sufficient dose of INDO may cause abortion, but the data taken together suggest this may be due to effects on the gut whereby permeability to bacterial LPS is increased.

Prostaglandin E and E2 alpha secretion by glandular and stromal cells of the pig endometrium in vitro: effects of estradiol-17 beta, progesterone, and day of pregnancy

Prostaglandins (PGs) are believed to play important roles in the establishment of pregnancy. Glandular and stromal cells were isolated from pig endometrium on days 11 through 19 of pregnancy and cultured in the presence of estradiol-17 beta (E2) and progesterone (P4) to determine the effect of day of pregnancy and steroids on the secretion of PGE and PGF2 alpha. Estradiol at concentrations between .01 and 1 microM did not affect PGE and PGF2 alpha secretion into the medium by glandular and stromal cells. Progesterone (.1 microM) suppressed (P less than .001) PGE and PGF2 alpha production from both cell types. Glandular cells secreted more (P less than .01) PGF2 alpha than PGE, whereas stromal cells collected on days 11, 12, 13, and 19 secreted more (P less than .05) PGE than PGF2 alpha. Stromal cells isolated from tissues collected on day 13 of pregnancy produced PGs with higher (P less than .01) PGE:PGF2 alpha ratio than those from tissues harvested on other days of pregnancy. Glandular cells isolated from tissues collected on days 13 and 19 and stromal cells isolated from tissue collected on day 13 of pregnancy secreted more (P less than .05) PGE and PGF2 alpha than cells isolated on other days of pregnancy. We conclude that: 1) P4 has a suppressing effect on PG secretion; 2) endometrial glandular and stromal cells each produce a unique profile of PGs; and 3) endometrial cells harvested on different days of pregnancy secrete different amounts of PGE and PGF2 alpha.

The mechanisms of action of progesterone and the anti-progestin ZK 98734 on PGF2 alpha synthesis by early human decidua

The inhibition of prostaglandin (PG) synthesis found in early human decidua is antagonized by the anti-progestin, ZK 98734. This action of ZK 98734 is abolished by actinomycin, an inhibitor of protein synthesis and by the calcium channel blocker, verapamil. Calmidazolium, an antagonist of the intracellular calcium binding protein calmodulin was less effective in inhibiting the stimulation of PG synthesis induced by the anti-progestin. Chronic stimulation of protein kinase C activity by 1-oleoyl-2-acetyl-sn-glycerol (OAG) induced a slight reduction of PG release and was antagonized by polymixin. These findings suggest that inhibition of PG synthesis in early pregnancy is caused by progesterone and that increased release of PGs induced by anti-progestins is dependent on new protein formation and requires extracellular calcium.

Prostaglandin production in human endometrium following continuous exposure to low-dose levonorgestrel released from a vaginal ring

Arachidonic acid metabolites produced by primary cultures of human endometrial cells derived from biopsies obtained before and after exposure to 20 micrograms/day levonorgestrel for 84 +/- 1 days were analysed by reverse phase HPLC. This revealed a significant increase in PGF1 alpha and an epoxide metabolite upon levonorgestrel stimulation. The proportion of epoxide metabolite, PGF1 alpha and PGE2 were positively correlated with serum levonorgestrel levels while HETES, PGE2 and epoxide were similarly correlated with serum oestradiol. The extent of intermenstrual bleeding during exposure to levonorgestrel was correlated with the proportion of epoxide and HETES products in vitro which is discussed in relation to their physiological function.

Is the inhibitory effect of progesterone on endometrial prostaglandin F2 alpha production due to an inhibition of protein synthesis?

Progesterone and a high concentration of oestradiol (i) reduced the outputs of prostaglandin (PG) F2 alpha and, to a lesser extent, PGE2 from Day-7 and Day-15 guinea-pig endometrium in culture, but had little or no effect on the output of 6-keto-PGF1 alpha, (ii) prevented the increase in PGH synthase concentrations which normally occur in Day-7 and Day-15 guinea-pig endometrium during culture, and (iii) reduced the synthesis of secreted proteins by Day-15 guinea-pig endometrium in culture. These findings suggest that the inhibitory effect of progesterone and of high concentrations of oestradiol on endometrium PGF2 alpha synthesis is due to an inhibition of the syntheses of proteins involved in PGF2 alpha production.

The immune function of the endometrium

The endometrial mucosa is unique amongst mucosal sites in that it must mount an immune response against micro-organisms and resist tumour growth whilst tolerating sperm and the allogeneic fetus. Bacterial and viral infection in the uterus leads to local endometrial mucosal immune responses evidenced by the secretion of secretory component (SC), secretory IgA (sIgA) and IgG. The secretion of these molecules is under hormonal control. Trafficking of locally sensitized lymphocytes to other mucosae does not appear to occur, whereas priming at other mucosal surfaces leads to memory responses to antigen in the uterus. Proclivity to local immune function is related to sparse lymphatic supply to the endometrium together with a local distribution of antigen-presenting dendritic cells. During pregnancy, particularly in the region of the decidua and embryo, the number of Ia+ cells and the lymphatic supply become diminished. The antigenic status of sperm may lead to certain types of maternal sensitization. However, immunosuppressive factors in seminal plasma protect the sperm on its passage up the female genital tract and diminish subsequent immunogenicity. On fertilization of the oocyte, an allogenic fetus develops, that potentially could stimulate production of maternal immune effectors. Endometrial cells of various types (macrophage, decidual, NK, T cells) interact via soluble factors leading to a local immunoprotection of the fetus. Similar factors appear to operate in resisting tumour growth in the uterus.