Glycodelin: a pane in the implantation window

Current Biomarkers for Endometrial Receptivity

Implantation and the continuation of pregnancy occur through a complicated and sophisticated dialogue, called “cross-talk,” which starts between the embryo and the endometrium in the early stages of oocyte maturation. This dialogue provides synchronization of the journey of the embryo to be implanted with the receptive endometrium. Understanding the activity and function of the hormones and factors involved in this dialogue will provide an understanding of endometrial receptivity, which plays a key role in implantation, and the determination of biomarkers specific for this period. As a result of the development of omics technology, it has become possible to identify biomarkers specific to endometrial receptivity by performing genomic, proteomic, and lipidomic analyses of these hormones and factors. The determination of these biomarkers, their optimization, and making them usable in the clinic will allow increased success in ART.

Endometrial Stromal Decidualization Responds Reversibly to Hormone Stimulation and Withdrawal

Human endometrial stromal decidualization is required for embryo receptivity, angiogenesis, and placentation. Previous studies from our laboratories established that connexin (Cx)-43 critically regulates endometrial stromal cell (ESC) differentiation, whereas gap junction blockade prevents it. The current study evaluated the plasticity of ESC morphology and Cx43 expression, as well as other biochemical markers of cell differentiation, in response to decidualizing hormones. Primary human ESC cultures were exposed to 10 nM estradiol, 100 nM progesterone, and 0.5 mM cAMP for up to 14 days, followed by hormone withdrawal for 14 days, mimicking a biphasic ovulatory cycle. Reversible differentiation was documented by characteristic changes in cell shape. Cx43 was reversibly up- and down-regulated after the estradiol, progesterone, and cAMP treatment and withdrawal, respectively, paralleled by fluctuations in prolactin, vascular endothelial growth factor, IL-11, and glycodelin secretion. Markers of mesenchymal-epithelial transition (MET), and its counterpart epithelial-mesenchymal transition, followed reciprocal patterns corresponding to the morphological changes. Incubation in the presence of 18α-glycyrrhetinic acid, an inhibitor of gap junctions, partially reversed the expression of decidualization and MET markers. In the absence of hormones, Cx43 overexpression promoted increases in vascular endothelial growth factor and IL-11 secretion, up-regulated MET markers, and reduced N-cadherin, an epithelial-mesenchymal transition marker. The combined results support the hypothesis that Cx43-containing gap junctions and endocrine factors cooperate to regulate selected biomarkers of stromal decidualization and MET and suggest roles for both phenomena in endometrial preparation for embryonic receptivity.

KLF11 epigenetically regulates glycodelin-A, a marker of endometrial biology via histone-modifying chromatin mechanisms

Endometrial biology is characterized by programmed proliferation and differentiation that is synchronous with ovarian folliculogenesis to maximize the chance of pregnancy. Glycodelin-A, an endometrial secretory protein, promotes pregnancy mostly through immunomodulatory mechanisms. Glycodelin-A is repressed during the proliferative and early secretory phase and activated thereafter. Progesterone activates glycodelin via the Sp1 (Specificity Protein 1) transactivator. We identify a novel role for Kruppel-like transcription factor 11 (KLF11) as a glycodelin-A repressor. Although KLF11 bound 2 distinct regulatory elements, it regulated glycodelin promoter activity differentially through each element. Whereas KLF11 weakly activated glycodelin promoter activity via a region that also bound Sp1, the dominant effect of KLF11 was repression of promoter activity, messenger RNA (mRNA), and protein expression via a novel, specific binding element. KLF11 mediated this repression by recruiting the SIN3/histone deacetylase (HDAC) corepressor complex to the glycodelin promoter. KLF11 may solely, or by competing with Sp1, repress glycodelin-A levels and thereby influence its role in the endometrium.

Immunopharmacology of ulipristal as an emergency contraceptive

A new progesterone antagonist, ulipristal has been made available as an emergency contraceptive. Ulipristal’s major mechanism of action as an emergency contraceptive has been ascribed to its ability to delay ovulation beyond the life span of the sperm. This paper analyzes the potential action of ulipristal (1) when unprotected intercourse and administration of ulipristal occur outside the fertility window and (2) when unprotected intercourse and administration of ulipristal occur at or within 24 hours of ovulation. When unprotected intercourse and the use of a single low dose of ulipristal occur outside of the fertility window, ulipristal behaves like a placebo. When unprotected intercourse and the use of a single low dose of ulipristal occur within the fertility window but before ovulation, ulipristal behaves like an emergency contraceptive by delaying ovulation and thereby preventing fertilization. When unprotected intercourse and the administration of ulipristal occur at or within 24 hours of ovulation, then ulipristal has an abortifacient action. It is proposed that the abortifacient mechanism of a low dose of ulipristal taken after fertilization but before implantation is due to the ability of ulipristal to block the maternal innate immune system to become immunotolerant to the paternal allogenic embryo. Progesterone’s critical immunotolerant actions involving early pregnancy factor, progesterone-induced blocking factor, and uterine natural killer cells are compromised by ulipristal.

Increased endometrial placenta growth factor (PLGF) gene expression in women with successful implantation

OBJECTIVE

To analyze the vascularization of the endometrium via hysteroscopy and to assess its correlation with angiogenic factor gene expression and embryo implantation rate.

DESIGN

Cross-sectional study.

SETTING

Public university hospital.

PATIENT(S)

Patients undergoing hysteroscopy for supposed infertility.

INTERVENTION(S)

Endometrial quality assessment according to Sakumoto-Masamoto, performed in the early secretory phase of the cycle. Collection of an endometrial tissue biopsy.

MAIN OUTCOME MEASURE(S)

RNA extraction, reverse transcription, and determination of gene expression of angiogenesis- and implantation-relevant factors using quantitative polymerase chain reaction. Retrieval of pregnancy information from the medical records.

RESULT(S)

Good quantity/quality RNA with infertility history was obtained from 63 participating women. Those with a "good" endometrium and subsequent pregnancy showed increased gene expression for placenta growth factor when compared with patients with a "bad" endometrium and who did not succeed with pregnancy to date. Nonpregnant women with a "good" endometrium presented an intermediate result. No significant differences were observed for several other genes tested, but trends in the same direction were observed.

CONCLUSION(S)

This study demonstrates for the first time that endometrial PLGF expression corresponds to the hysteroscopic appearance of the endometrium, and therefore has potential as a clinically relevant prognosticator for infertility treatment success.

Inflammation in reproductive disorders

Inflammatory disorders account for a significant percentage of gynecologic disease, particularly in reproductive age women. Inflammation is a basic method by which we respond to infection, irritation, or injury. Inflammation is now recognized as a type of nonspecific immune response, either acute or chronic. In gynecology, inflammation leads to anatomic disorders primarily as a result of infectious disease; however inflammation can affect ovulation and hormone production as well as be associated with endometriosis. Similarly, immune cell trafficking is an important component of cyclic endometrial development in each menstrual cycle. These immune cells are required for endometrial function, producing a vast array of inflammatory cytokines. Inflammation alters endometrial receptivity, however it may also play a role in tissue repair and remodeling. Finally, inflammation affects the trophoblast and trophoblast-endometrial interaction. Some components of the immune response are required for optimal fertility and normal tissue remodeling. A better understanding of the necessary role of inflammation in reproduction will allow more rational and targeted treatment of inflammatory disorders in reproductive medicine.

Molecular analysis of human endometrium: short-term tibolone signaling differs significantly from estrogen and estrogen + progestagen signaling

Tibolone, a tissue-selective compound with a combination of estrogenic, progestagenic, and androgenic properties, is used as an alternative for estrogen or estrogen plus progesterone hormone therapy for the treatment of symptoms associated with menopause and osteoporosis. The current study compares the endometrial gene expression profiles after short-term (21 days) treatment with tibolone to the profiles after treatment with estradiol-only (E₂) and E₂ + medroxyprogesterone acetate (E₂ + MPA) in healthy postmenopausal women undergoing hysterectomy for endometrial prolapse. The impact of E₂ treatment on endometrial gene expression (799 genes) was much higher than the effect of tibolone (173 genes) or E₂ + MPA treatment (174 genes). Furthermore, endometrial gene expression profiles after tibolone treatment show a weak similarity to the profiles after E₂ treatment (overlap 72 genes) and even less profile similarity to E₂ + MPA treatment (overlap 17 genes). Interestingly, 95 tibolone-specific genes were identified. Translation of profile similarity into biological processes and pathways showed that ER-mediated downstream processes, such as cell cycle and cell proliferation, are not affected by E2 + MPA, slightly by tibolone, but are significantly affected by E₂. In conclusion, tibolone treatment results in a tibolone-specific gene expression profile in the human endometrium, which shares only limited resemblance to E₂ and even less resemblance to E2 + MPA induced profiles.

PAPP-A and osteoprotegerin, together with interleukin-8 and RANTES, are elevated in the peritoneal fluid of women with endometriosis

OBJECTIVE

The purpose of this study was to evaluate whether pregnancy-associated plasma protein A, glycodelin, osteoprotegerin, and soluble CD163 are possible peritoneal fluid markers for endometriosis and to compare them with the established chemokine markers interleukin-8 and regulated on activation, normal T-cell expressed and secreted.

STUDY DESIGN

Determination of the concentrations of interleukin-8, regulated on activation, normal T-cell expressed and secreted, pregnancy-associated plasma protein A, glycodelin, CD163, osteoprotegerin, and progesterone in the peritoneal fluid collected from women undergoing laparoscopy.

RESULTS

From a total of 132 women, 77 women were diagnosed with endometriosis, and 55 women were free of the disease and served as control subjects. Pregnancy-associated plasma protein A and osteoprotegerin showed significantly (P < 0.05) elevated peritoneal fluid concentrations as a function of the severity of the disease, together with interleukin-8 and regulated on activation, normal T-cell expressed and secreted (P < .001). Glycodelin and CD163 did not differ between cases and control subjects. Many of these marker concentrations were intercorrelated strongly.

CONCLUSION

Pregnancy-associated plasma protein A and osteoprotegerin may play a role in the inflammation process of endometriosis, but interleukin-8 and regulated on activation, normal T-cell expressed and secreted are superior peritoneal fluid markers.

2,3,7,8-Tetrachlorodibenzo-p-dioxin increases glycodelin gene and protein expression in human endometrium

CONTEXT

Glycodelin (GdA) is an immunosuppressive endometrial glycoprotein critical for embryonic implantation and pregnancy establishment.

OBJECTIVE

The aim of the present study was to examine the effect of dioxin [2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD)] on GdA production in human endometrial cells.

DESIGN

Controlled endometrial explant (EE) and cell cultures were used in this study.

SETTING

Work was conducted at university hospital research laboratories in Bern, Switzerland, and in San Francisco, California.

PATIENTS

Ovulatory women provided endometrial biopsies in the proliferative or secretory phase.

INTERVENTION(S)

EEs and cells were cultured without and with TCDD.

MAIN OUTCOME MEASURE(S)

GdA protein and gene expression were quantified.

RESULTS

A 2.5-fold increase in GdA production was demonstrated in EEs treated with 10 nm TCDD for 9 d. Fluorography revealed a 3- to 4-fold increase in new GdA biosynthesis and secretion in TCDD-treated endometrial epithelial cells. Because the action of dioxin is mediated by the aryl hydrocarbon receptor (AhR), we ascertained that primary epithelial and Ishikawa cells express AhR. Dose responses to TCDD and expressed AhR were established in transiently transfected Ishikawa cells using luciferase fusion vectors containing 1.0 kb of 5' flanking DNA relative to the GdA transcriptional start site but not when shorter promoter constructs were used. A dioxin response element was mapped to nucleotides -539 to -533 of the gene promoter and verified by site-directed mutagenesis.

CONCLUSIONS

We demonstrated a direct AhR-mediated effect of dioxin on GdA gene transcription and protein secretion that might influence human female fertility.

The value of a single combined measurement of VEGF, glycodelin, progesterone, PAPP-A, HPL and LIF for differentiating between ectopic and abnormal intrauterine pregnancy

BACKGROUND

To evaluate whether serum concentrations of the non-placental markers vascular endothelial growth factor (VEGF), glycodelin (GLY) and progesterone (P) and the novel placental markers pregnancy-associated plasmaprotein A (PAPP-A), human placental lactogen (HPL) and leukaemia inhibiting factor (LIF) differ in ectopic pregnancy (EP) when compared with abnormal intrauterine pregnancy (aIUP).

METHODS

A prospective clinical study was conducted at the University Hospital of Larissa, Greece. The study included 50 patients admitted with failed pregnancy and suspected ectopic pregnancy that were treated with curettage or laparoscopy and classified as histologically confirmed EPs (n = 27) or histologically confirmed aIUPs (n = 21) (mean gestational age of 7.15 and 7.3 weeks, respectively). Two suspected EPs proved to be normal IUPs and were excluded. VEGF, GLY, P, beta-HCG, PAPP-A, HPL and LIF were measured by enxyme-linked immunosorbent assay (ELISA) methods in a single pre-operative blood sample.

RESULTS

The median VEGF concentration was 227.2 pg/ml in the EP group versus 107.2 pg/ml in the aIUP group (P < 0.001), with a suggested threshold value of 174 pg/ml for their differential diagnosis. LIF, P, PAPP-A, HPL and GLY serum measurements did not differ significantly between EP and aIUP.

CONCLUSION

VEGF serum levels might be a useful marker in differentiating between EPs and aIUPs.

Glycodelin responses to hyperinsulinaemic clamp vary according to basal serum glycodelin concentration

OBJECTIVE

Treatment with metformin, an insulin-lowering agent, increases serum glycodelin, a progesterone-regulated lipocalin protein of the reproductive axis that may play a role in foeto-maternal defence mechanisms. This finding led to the hypothesis that insulin might decrease serum glycodelin concentration.

DESIGN, PATIENTS AND MEASUREMENTS

Euglycaemic hyperinsulinaemic clamp experiments (n = 50) were carried out on 28 women of reproductive age (range 25-47 years; mean +/- SEM 39 +/- 1.0 years), and the results were analysed with respect to their baseline serum progesterone (< 10 or > or = 10 nmol/l) and glycodelin (< 10 or > or = 10 microg/l, equivalent to < 357 or > or = 357 pmol/l) concentrations at the onset of the clamp. Ten clamp experiments were performed on five women wearing a levonorgestrel-releasing intrauterine device (IUD), and these were analysed as a separate group.

RESULTS

Contrary to the hypothesis, no acute glycodelin-lowering effect of insulin was found in any of the groups studied. All the small rises in glycodelin levels detected during acute hyperinsulinaemia occurred in the comparisons of medians and not means, and all such changes took place within the limits seen in the women with no progesterone exposure. In the group with low progesterone/low glycodelin (n = 21), glycodelin showed a small but significant increase at 30 and 90 min of the clamp (P < 0.01). In the group with elevated progesterone/low glycodelin (n = 11), there was a slight glycodelin increase at 30 min (P < 0.05), whereas no increase was found in the group with elevated glycodelin levels (n = 8). In the clamp experiments on women with levonorgestrel-releasing IUD, the basal glycodelin level was low in all cases and, as in the other women with low glycodelin levels, glycodelin was slightly increased at 30, 60 and 90 min of hyperinsulinaemia (P < 0.01).

CONCLUSIONS

The results rule out any acute glycodelin-reducing effects of insulin, although indirect long-term effects mediated by insulin on glycodelin secretion cannot be excluded.

Laboratory testing for endometriosis

BACKGROUND

Typically, endometriosis is diagnosed surgically by laparoscopy. CA-125 is the principal serum marker used in the diagnosis and management of late-stage endometriosis. The search for a body fluid marker of early stage disease has included studies of serum, peritoneal fluid (PF), and/or tissue levels of secretory proteins, cell adhesion molecules, cytokines, tumor necrosis and vascular endothelial growth factors (VEGFs), chemokines, antiendometrial antibodies, autoantibodies to oxidized lipoproteins, aromatase P-450 expression, cytokeratins, and hormone receptors. We compared the diagnostic accuracy and clinical utility of these various types of substances in the non-surgical identification of patients with endometriosis.

METHOD

We reviewed the MEDLINE database for all publications on serum, peritoneal fluid and tissue markers of endometriosis.

RESULTS

Except for serum interleukin (IL)-6 and peritoneal fluid tumor necrosis factor (TNF)-alpha levels, the diagnostic accuracy of other markers of endometriosis was either similar or worse than that of CA-125 (sensitivity 24-94%; specificity 83-93%). The diagnostic accuracy of IL-6 and TNF-alpha was 90-100% (sensitivity) and 67-89% (specificity).

CONCLUSION

CA-125 has limited diagnostic accuracy in the identification of early stage endometriosis and none of the other markers we reviewed dramatically outperformed CA-125 in this regard with the possible exception of serum IL-6 and peritoneal fluid TNF-alpha levels.

Novel placental and nonplacental serum markers in ectopic versus normal intrauterine pregnancy

OBJECTIVE

To evaluate whether the serum concentrations of novel placental markers and nonplacental markers differ in ectopic pregnancy when compared with normal intrauterine pregnancy.

DESIGN

Prospective clinical study.

SETTING

University hospital.

PATIENT(S)

Patients with confirmed ectopic pregnancy (EP) and control population with normal intrauterine pregnancy (IUP).

INTERVENTION(S)

Laparoscopy.

MAIN OUTCOME MEASURE(S)

Serum concentrations of placental markers: pregnancy-associated plasma protein A (PAPP-A), pregnancy-specific beta(1)-glycoprotein (SP1), human placental lactogen (HPL), and HCG; and nonplacental markers: glycodelin, vascular endothelial growth factor (VEGF), and P.

RESULT(S)

The multiples of median of all markers (except VEGF) were decreased in EP when compared with the control group. Conversely, the serum values of VEGF were significantly increased in EP. VEGF showed a negative correlation with HCG and SP1, but not with PAPP-A, P, or the nonplacental markers. HCG, PAPP-A, SP1, and HPL strongly correlated with each other. But, in contrast to the above, P only correlated with HCG and, in contrast to the controls, with glycodelin. The combination of three independent markers in the formula VEGF/(PAPP-A x P) was found to be largely superior to the measure of any single marker.

CONCLUSION(S)

The "triple marker analysis" [VEGF/(PAPP-A x P] allows a clear discrimination between normal IUP and EP.

Placental protein 14 concentrations in circulation related to hormonal parameters and reproductive outcome in women undergoing IVF/ICSI

Serum concentrations of placental protein 14 (PP14), steroids and gonadotrophins were related to the outcome of IVF/intracytoplasmic sperm injection in 195 normogonadotrophic women subjected to the long protocol gonadotrophin-releasing hormone agonist (GnRHa; buserelin) pituitary down-regulation protocol and gonadotrophin stimulation (HMG or rFSH). Pituitary down-regulation was initiated on cycle day 21 and the patients were randomized to either intranasal or s.c. administration of buserelin. After 14 days of down-regulation, the patients were randomized on stimulation day 1 (S1) to ovarian stimulation with 225 IU per day of either human menopausal gonadotrophin (HMG) or recombinant FSH (rFSH) for a fixed period of 7 days. The daily gonadotrophin dose was adjusted on the following day according to ovarian response. Patient's blood was sampled for PP14 and hormone analysis on cycle days 21, S1, S8 and on the day of oocyte retrieval. Mean concentrations of PP14 on day 21 of the cycle were significantly lower in conception than in non-conception cycles, whereas progesterone and oestradiol were similar in conception and non-conception cycles. PP14 concentrations on the first day of stimulation and at oocyte retrieval were significantly higher in conception than in non-conception cycles, whereas concentrations after 8 days of stimulation were similar. Neither mode of GnRHa administration nor type of gonadotrophin significantly influenced PP14 concentrations throughout ovarian stimulation. Circulating PP14 is thus an important physiological signal of the fertility status of the individual in the cycle antecedent to and during ovarian stimulation. Measuring mid-luteal serum PP14 may offer a clinical test helping to decide if infertility treatment should be initiated in the subsequent cycle.

Glycodelin serum levels in women with ectopic pregnancy

OBJECTIVE

Aim of our study was to determine circulating levels of glycodelin for biochemical monitoring of women with vaginal bleeding and/or abdominal pain in early pregnancy. The objective was, using glycodelin as a biochemical parameter, to distinguish between incomplete abortion and ectopic pregnancy in early weeks of gestation.

STUDY DESIGN

In 169 women with a first trimester pregnancy, a single serum measurement of maternal glycodelin was taken. Patients were divided into groups according to the clinical and/or ultrasonografic findings at the time of hospitalisation:ectopic pregnancy, incomplete abortion and control.

RESULTS

Glycodelin serum levels were significantly lower in patients with ectopic pregnancy comparable with intact pregnancy and incomplete abortion. There was no difference in serum levels between intact pregnancy and incomplete abortion.

CONCLUSION

Glycodelin might represent a biochemical parameter in the differential diagnosis between ectopic pregnancies and incomplete abortion. The number of patients was too small to give reference ranges for pregnancy weeks.

Emerging role of genomics in endometriosis research

OBJECTIVE

Rapidly evolving methods in genomics and proteomics research already are changing the nature of biomedical investigation. In this report we briefly review some of the seminal technological advances that inspired the genomics revolution and describe their application in the field of endometriosis research.

DESIGN

Review of different techniques successfully applied to endometriosis research.

SETTING

Collaborative investigation in academic and pharmaceutical industry laboratories.

PATIENT(S)

Biopsies were obtained from consenting ovulatory women on no medications, with or without laparoscopically proven endometriosis.

RESULT(S)

Genomics techniques have confirmed gene products shown to be abnormally expressed in endometriotic tissues by prior studies. In addition, identification of novel transcripts not previously appreciated in this condition were discovered. Examples of dysregulated genes in endometriosis include glycodelin, complement, early growth response-1 and transducer of erbB-1.

CONCLUSION(S)

Global gene profiling studies are poised to revolutionize the diagnosis and treatment of endometriosis and other human diseases.

Glycodelin: a major lipocalin protein of the reproductive axis with diverse actions in cell recognition and differentiation

Glycodelin is a glycoprotein that belongs to the lipocalin superfamily. Depending on glycosylation, glycodelin appears in various isoforms. In the uterus, glycodelin-A is the major progesterone-regulated glycoprotein secreted into uterine luminal cavity by secretory/decidualized endometrial glands. The other tissues expressing glycodelin include fallopian tubes, ovary, breast, seminal vesicle, bone marrow, and eccrine glands. Glycodelin-A potently and dose-dependently inhibits human sperm-egg binding, whereas differently glycosylated glycodelin-S from seminal plasma has no such effect. Absence of contraceptive glycodelin-A in the uterus during periovulatory midcycle is consistent with an open "fertile window." Glycodelin induced by local or systemic administration of progestogens may potentially reduce the fertilizing capacity of sperm in any phase of the menstrual cycle. Glycodelin also has immunosuppressive activity. Its high concentration at the fetomaternal interface may contribute to protection of the embryonic semiallograft. Besides being an epithelial differentiation marker, glycodelin appears to play a role in glandular morphogenesis, as transfection of glycodelin cDNA into a glycodelin-negative breast cancer cells resulted in formation of gland-like structures, restricted proliferation, and induction of other epithelial markers. These various properties, as well as the chemistry, biology, and clinical aspects of glycodelin, continue to be areas of active investigation reviewed in this communication.