Determination of IL-1 and IL-6 levels in human embryo culture-conditioned media

Interleukin-6 Concentration in Single-Embryo Medium Is Associated with Blastocyst Formation

IL-6 plays an important role in oogenesis in humans. However, at the preimplantation stage, IL-6 production and the role in embryo development remain unclear. In this study, IL-6 concentrations in single-embryo media were analyzed. In addition, the association between IL-6 production and blastocyst formation was investigated. Single-embryo culture media from 194 embryos were collected on day 6 after fertilization and divided into four groups according to the developmental stage of the corresponding embryo, as follows: cleavage stage group, morula-early blastocyst group, unavailable full blastocyst group, and available full blastocyst group. IL-6 concentrations were significantly lower in the cleavage stage group than in the morula-early blastocyst group (p = 0.009), in the unavailable full blastocyst group (p = 0.003), and in the available full blastocyst group (p < 0.001). Logistic regression analysis showed that IL-6 concentration in single-embryo medium was significantly associated with blastocyst formation (odds ratios β1 = 1.876, 95% CI 1.433 to 2.644, p < 0.0001). Therefore, IL-6 was produced by human preimplantation embryos throughout the preimplantation stage and may play a role in embryo development.

Cytokines in embryonic secretome as potential markers for embryo selection

Despite performing certain morphological assessments for selecting the best embryo for transfer, the results have not been satisfactory. Given the global tendency for performing quick and noninvasive tests for embryo selection, great efforts have been made to discover the predictive biomarkers of embryo implantation potential. In recent years, many factors have been detected in embryo culture media as a major source of embryo secretions. Previous studies have evaluated cytokines, miRNAs, extracellular vesicles, and other factors such as leukemia inhibitory factor, colony-stimulating factor, reactive oxygen species, soluble human leukocyte antigen G, amino acids, and apolipoproteins in these media. Given the key role of cytokines in embryo implantation, these factors can be considered promising molecules for predicting the implantation success of assisted reproductive technology (ART). The present study was conducted to review embryo-secreted molecules as potential biomarkers for embryo selection in ART.

Simultaneous detection of two growth factors from human single-embryo culture medium by a bead-based digital microfluidic chip

The measurement of growth factors released in a culture medium is considered to be an attractive non-invasive approach, apart from the embryo morphology, to identify the condition of an embryo development after fertilization in vitro (IVF), but the available embryo culture medium in the current method is only a few microlitres. This small sample volume, also of small concentration, makes difficult the application of a conventional detection method, such as an enzyme-linked immunosorbent assay (ELISA). A reliable detection of the growth factor from each embryo culture medium of such a small concentration hence remains a challenge. Here for the first time we report the results of measurement of not just one, but two, growth factors, human IL-1β and human TNF-α, from an individual droplet of embryo culture medium with a bead-based digital microfluidic chip. The required sample volume for a single measurement is only 520 nL; the total duration of the on-chip process is less than 40 min. Using the culture media of human embryos with normal morphologic features, we found that the concentrations of TNF-α change little from day 3 to day 5-6, but the concentrations of IL-1β for some embryos might double from day 3 to day 5-6. For other embryos even with similar normal morphologic features, some growth factors, such as IL-1β, might exhibit different expressions during the culture period. Those growth factors could serve to distinguish the development conditions of each embryo, not merely from an observation of embryo morphology.

Anti-inflammatory and phytochemical evaluation of Combretum aculeatum Vent growing in Sudan

ETHNOPHARMACOLOGICAL RELEVANCE

Combretum aculeatum Vent was traditionally used in Sudan, Eretria and Ethiopia as anti-inflammatory in case of skin inflammation, catarrh, wounds, scorpion stings and snake bites. Nevertheless, there is no scientific information regarding this activity.

AIM OF STUDY

The present study aimed to evaluate the phytochemical constituents and the scientific basis for the traditional use of Combretum aculeatum Vent through studying its anti-inflammatory properties for the first time to illustrate the putative mechanisms behind this bioactivity.

MATERIALS AND METHODS

the ethanolic extract was partitioned by petroleum ether, methylene chloride, ethyl acetate, and n-butanol saturated with water. The petroleum ether fraction was saponified and the saponifiable and unsaponifiable fractions were analyzed on GC/MS. The different fractions were subjected to phytochemical investigation to isolate pure compounds. In-vivo anti-inflammatory activity of the ethanolic extract was evaluated using carrageenan induced rat paws edema method at doses of 200, 400 and 600 mg/kg and proved based on histopathological and biochemical parameters.

RESULTS

Five known compounds were isolated for the first time from the aerial parts of Combretum aculeatum Vent: quercetin, vitexin, isorhamnetin 3-O-β-glucoside, isovitexin and rutin, in addition to two previously isolated ones: β-sitosterol and its glucoside. The ethanolic extract evidenced in-vivo anti-inflammatory activity by oral intake of 400 mg/kg of the ethanolic extract significantly (P ≥ 0.05) decreased the paw edema (only 32±1.9% increase in paw weight after 4 h) compared to indomethacin (28.6±2.5%). Moreover, it significantly suppressed the serum malondialdehyde (MDA) and nitric oxide (NO) and increased the GSH to be 11.76±0.85, 5.13±0.62 μmol/mL and 5.66±0.28 μM/mL, respectively. It diminished the serum cytokines TNF-α, IL-6 and IL-1β levels to be 39.1±1.2, 32.6±1.1 and 37.5±1.2 pg/mL, respectively. Results are accompanied by histopathological examination.

CONCLUSION

Overall, the results herein presented significant anti-inflammatory properties traditionally ascribed to Combretum aculeatum Vent. Moreover, the biochemical mechanisms associated to this action were highlighted, introducing new prospects for the development of effective anti-inflammatory herbal medicinal products.

Murine embryos exposed to human endometrial MSCs-derived extracellular vesicles exhibit higher VEGF/PDGF AA release, increased blastomere count and hatching rates

Endometrial Mesenchymal Stromal Cells (endMSCs) are multipotent cells with immunomodulatory and pro-regenerative activity which is mainly mediated by a paracrine effect. The exosomes released by MSCs have become a promising therapeutic tool for the treatment of immune-mediated diseases. More specifically, extracellular vesicles derived from endMSCs (EV-endMSCs) have demonstrated a cardioprotective effect through the release of anti-apoptotic and pro-angiogenic factors. Here we hypothesize that EV-endMSCs may be used as a co-adjuvant to improve in vitro fertilization outcomes and embryo quality. Firstly, endMSCs and EV-endMSCs were isolated and phenotypically characterized for in vitro assays. Then, in vitro studies were performed on murine embryos co-cultured with EV-endMSCs at different concentrations. Our results firstly demonstrated a significant increase on the total blastomere count of expanded murine blastocysts. Moreover, EV-endMSCs triggered the release of pro-angiogenic molecules from embryos demonstrating an EV-endMSCs concentration-dependent increase of VEGF and PDGF-AA. The release of VEGF and PDGF-AA by the embryos may indicate that the beneficial effect of EV-endMSCs could be mediating not only an increase in the blastocyst’s total cell number, but also may promote endometrial angiogenesis, vascularization, differentiation and tissue remodeling. In summary, these results could be relevant for assisted reproduction being the first report describing the beneficial effect of human EV-endMSCs on embryo development.

Secretome derived from different cell lines in bovine embryo production in vitro

The present study investigated the effects of conditioned medium (CM), composed of microvesicles (MVs) and soluble factors present in the supernatant (SN), of bovine endometrial and amniotic cells on embryo quality and rate of blastocyst production. Presumptive zygotes were randomly assigned on Days 1, 3 and 5 after fertilisation to synthetic oviducal fluid with amino acids (SOFaa; control) or to SOFaa supplemented with either 20% endometrial or amniotic CM, 20% SN or 100 × 106 MVs mL−1. Embryos were evaluated on Day 7. For groups supplemented with MVs derived from either endometrial or amniotic cells on Day 1 of culture, blastocysts had developed, but at a lower rate than in the control group. Blastocysts had developed in all groups in which endometrial or amniotic cell-derived CM or MVs were added on Day 3 of culture, but the rate of blastocyst development was significantly lower in both CM groups than in the MVs groups. The addition of all secretome fractions (CM, MVs and SN) derived from either bovine endometrial or amniotic cells on Day 5 of culture resulted in blastocyst production, but only amniotic MVs resulted in a blastocyst production rate comparable to that in the control group. Supplementation of SOFaa on Day 5 resulted in a qualitatively higher number of inner cell mass cells compared with the control group only for the amniotic CM and MVs groups. At day 7, these data were confirmed by RT-qPCR evaluation of genes (Bcl-2-associated X protein (BAX) and glutathione peroxidase 1 (GPX1) involved in apoptosis and protection against reactive oxygen species. In conclusion, of the different secretome fractions tested, only amniotic MVs added to SOFaa resulted in better outcomes than in the control group.

Regulation of inflammatory and angiogenesis mediators in a functional model of decidualized endometrial stromal cells

The mechanisms involving the expression of interleukin (IL) 1 family members in the process of preparing the endometrium to receive an embryo remain unclear. In this study, decidualization differentially skewed the balance of IL1 family receptor expression in a pattern that increases endometrial stromal cell receptivity to IL1, IL18 and IL33. Additionally, endometrial cells showed increased expression of homeobox HOXA10 and HOXA11 and LIFR, which are known to be involved in endometrial embryo receptivity. Further analyses of decidual endometrial cells revealed a significant increase in the release of potent proinflammatory, remodelling and angiogenic factors implicated in the embryo invasion process, such as VEGF (P = 0.0305), MMP9 (P = 0.0003), TIMP3 (P = 0.0001), RANTES (P = 0.0020), MCP1 (P = 0.0001) and MIF (P = 0.0068). No significant changes in endogenous IL1B secretion were observed. Decreased secretion of IL18 and decidualization increased secretion of IL33. These findings reveal a significant modulation of endometrial cell receptivity to IL1 family members during endometrial stromal cell decidualization, and suggest that the involvement of IL1 family members is important in physiological processes of endometrial receptivity, including adaptive immunology. This may be relevant to establishing a favourable uterine microenvironment for embryo implantation.

Expression and localization of interleukin 1 beta and interleukin 1 receptor (type I) in the bovine endometrium and embryo

The interleukin-1 (IL1) system likely mediates mammalian embryo-maternal communication. In cattle, we have reported that the uterine fluid of heifers carrying early embryos shows downregulated IL1 beta (IL1B), which could lead to reduced NFkB expression and dampening of maternal innate immune responses. In this work, we assessed the expression of IL 1 beta (IL1B) and its receptor, interleukin 1 receptor type I (IL1R1) in the bovine endometrium and embryos by RT-PCR, immunohistochemistry and Western blot at the time of blastocyst development. Day 8 endometrium, both collected from animals after transfer of day 5 embryos (ET) and sham transferred (ST), showed IL1B and IL1R1 mRNA transcription and protein co-localization. Similarly, day 8 blastocyst, from ET animals and entirely produced in vitro, showed IL1R1 mRNA transcription and IL1B and IL1R1 protein co-localization. IL1B mRNA was detected in the analyzed blastocysts, but at very low levels that precluded its quantification. IL1B and IL1R1 immunostaining was observed in luminal epithelial cells, glandular epithelium and stromal cells. The presence of embryos increased endometrial IL1B protein locally, while no differences regarding IL1R1 protein and IL1B and IL1R1 mRNA were detected. These results suggest that the early preimplantation bovine embryo in the maternal tract might interact with the maternal immune system through the IL1 system. Such a mechanism may allow the embryo to elicit local endometrial responses at early stages, which are required for the development of a receptive endometrium.

Soluble ligands and their receptors in human embryo development and implantation

Extensive evidence suggests that soluble ligands and their receptors mediate human preimplantation embryo development and implantation. Progress in this complex area has been ongoing since the 1980s, with an ever-increasing list of candidates. This article specifically reviews evidence of soluble ligands and their receptors in the human preimplantation stage embryo and female reproductive tract. The focus will be on candidates produced by the human preimplantation embryo and those eliciting developmental responses in vitro, as well as endometrial factors related to implantation and receptivity. Pathways to clinical translation, including innovative diagnostics and other technologies, are also highlighted, drawing from this collective evidence toward facilitating joint improvements in embryo quality and endometrial receptivity. This strategy could not only benefit clinical outcomes in reproductive medicine but also provide broader insights into the peri-implantation period of human development to improve fetal and neonatal health.

Uterine flushing with supernatant embryo culture medium in vitrified warmed blastocyst transfer cycles: a randomized controlled trial

PURPOSE

Does transfer of supernatant embryo culture fluid (stimulation of endometrial embryo transfer - SEET) prior to vitrified warmed blastocyst transfer result in better clinical pregnancy and live birth rates than direct vitrified warmed blastocyst transfer?

METHODS

This randomized controlled trial compared SEET group and direct transfer group (control) in 60 women undergoing vitrified warmed blastocyst transfers. The duration of the study was 3 years. The patients were undergoing vitrified warmed blastocyst transfer at university level infertility centre. Sixty women were randomized to SEET (n = 30) or control (n = 30).

RESULTS

Data was available for analysis from all the 30 women in the SEET group and 30 women in the control group. There were no drop outs in the trial. The implantation rate was significantly lower in the SEET group compared to the control group (27 vs. 44 %, P = 0.018). The clinical pregnancy rates were similar in both the groups (47 vs. 53 %) but the live birth rate was also significantly lower in SEET group (23 vs. 50 %, P = 0.03).

LIMITATIONS

The sample size based on clinical pregnancy rates was small and hence not adequately powered to detect differences in live birth rates. Lack of blinding leading to possible bias cannot be ruled out.

CONCLUSION

There was no evidence of an improvement in clinical pregnancy rate following SEET in vitrified warmed blastocyst transfer compared to direct transfer.

Improvement of cloned embryos development by co-culturing with parthenotes: a possible role of exosomes/microvesicles for embryos paracrine communication

It is well known that embryos cultured in a group can create a microenvironment through secretion of autocrine and paracrine factors that can support and improve the embryos' development when compared to the embryos cultured individually. In this study, we used a co-culture system for paracrine communication between different kinds of embryos. The results showed that co-culture of porcine parthenogenetic (PA) embryos significantly improved the in vitro development of cloned (nuclear transfer, NT) embryos. To reveal the possible mechanism of communication between the two groups, we isolated exosomes/microvesicles (EXs/MVs) from the PA embryos conditioned medium (PA-CM) through differential centrifugation and identified them through transmission electron microscope and immunoflourescence against exosomal/membrane marker CD9. Furthermore, these EXs/MVs were found to contain mRNA of pluripotency genes (Oct4, Sox2, Klf4, c-Myc, and Nanog), and the PKH67-labeled EXs/MVs could be internalized by the NT embryos. The current study demonstrates that cloned embryos' developmental competence can be improved through co-culturing with PA embryos and revealed, for the first time, that in vitro-produced embryos can secrete EXs/MVs as a possible communication tool within their microenvironment. Moreover, it provides a new paradigm for embryo-to-embryo communication in vitro.

Transcriptome analysis reveals new insights into the modulation of endometrial stromal cell receptive phenotype by embryo-derived signals interleukin-1 and human chorionic gonadotropin: possible involvement in early embryo implantation

The presence of the conceptus in uterine cavity necessitates an elaborate network of interactions between the implanting embryo and a receptive endometrial tissue. We believe that embryo-derived signals play an important role in the remodeling and the extension of endometrial receptivity period. Our previous studies provided original evidence that human Chorionic Gonadotropin (hCG) modulates and potentiates endometrial epithelial as well as stromal cell responsiveness to interleukin 1 (IL1), one of the earliest embryonic signals, which may represent a novel pathway by which the embryo favors its own implantation and growth within the maternal endometrial host. The present study was designed to gain a broader understanding of hCG impact on the modulation of endometrial cell receptivity, and in particular, cell responsiveness to IL1 and the acquisition of growth-promoting phenotype capable of receiving, sustaining, and promoting early and crucial steps of embryonic development. Our results showed significant changes in the expression of genes involved in cell proliferation, immune modulation, tissue remodeling, apoptotic and angiogenic processes. This points to a relevant impact of these embryonic signals on the receptivity of the maternal endometrium, its adaptation to the implanting embryo and the creation of an environment that is favorable for the implantation and the growth of this latter within a new and likely hostile host tissue. Interestingly our data further identified a complex interaction between IL1 and hCG, which, despite a synergistic action on several significant endometrial target genes, may encompass a tight control of endogenous IL1 and extends to other IL1 family members.

Preimplantation human blastocyst-endometrial interactions: the role of inflammatory mediators

Immune factors such as cytokines, chemokines, and growth factors are known to play important roles in the preimplantation interactions and communication between the blastocyst and receptive endometrium. This crucial dialog occurs during the stages when the blastocyst is in the uterine cavity immediately preceding implantation and the establishment of pregnancy. Human preimplantation processes are difficult to study due to restrictions on tissue availability. This review focuses on the expression and role of immune factors in human blastocyst-endometrial dialog during the very early stages of implantation. It highlights the importance of immune regulators and the need to develop new models to study human implantation.

Detection of IL-1β in culture media supernatants of pre-implantation human embryos; its relation with embryo grades and development

In this study, we aimed to determine whether human embryos secrete interleukin-1β (IL-1β) into culture media and its correlation with embryo grade and development. Culture media supernatants of 100 embryos obtained from 39 cycles of 38 patients and cultivated individually were collected 2 and 3 days after intracytoplasmic sperm injection (ICSI). IL-1β concentrations of samples were determined with ELISA and compared with embryo grades and blastomere numbers. Embryo grades and the amount of IL-1β they secreted were found not to be correlated (p:0.559). Numbers of blastomeres each embryo had at 2nd and 3rd days were found to be correlated with IL-1β secreted (p:0.00 and p:0.00, respectively). Mean amount of IL-1β secreted by the embryos from ejaculated sperm cycles were found to be significantly higher than that of embryos from TESE cycles (p:0.016). Patient age and etiology of infertility were not correlated with the amount of IL-1β secreted and embryo grade. In conclusion, preimplantation human embryos secrete IL-1β in their media in amounts correlated with their blastomere numbers.

Interaction of the conceptus and endometrium to establish pregnancy in mammals: role of interleukin 1β

Implantation and the establishment of pregnancy in mammals involves an intricate interplay of hormones, cytokines, growth factors, proteins, lipids, ions and the extracellular matrix between the uterine epithelium, stroma, immune cells and the conceptus trophectoderm. The divergent nature of implantation in the mouse, human and pig provides not only an interesting contrast in the establishment of pregnancy and early embryonic development but also intriguing similarities with regard to early endometrial-conceptus signaling. An interesting pro-inflammatory cytokine expressed in a number of mammalian species during the period of implantation is interleukin-1β (IL1B). The presence of IL1B might be involved with immunotolerance at the maternal-placental interface and has been proposed as one of the mediators in placental viviparity. The production of IL1B and other proinflammatory cytokines might play a role in establishing pregnancy through modulation of the nuclear factor kappa-B (NFKB) system in a number of species. A model for the regulation of cellular progesterone receptor expression and NFKB activation for endometrial receptivity and conceptus attachment is continuing to evolve and is discussed in the present review.

Cytokines and Growth Factors in Implantation

Implantation failure is the most important rate limiting factor in the success of assisted reproductive techniques like In vitro fertilization–embryo transfer (IVF-ET). Cytokines are multifunctional signaling molecules having an implicit role in the human implantation process. This review focuses on the redundant roles of cytokines during the various stages of implantation. It also indicates that levels of cytokines in biological fluids like serum and follicular fluid obtained during oocyte retrieval might act as determinants of implantation potential of the blastocyst. Thus a holistic, metabolomic approach of analyzing biological fluids may provide a simpler approach to study the hitherto enigmatic process rather than the proteomic and genomic approach.

An additive interaction between the NFkappaB and estrogen receptor signalling pathways in human endometrial epithelial cells

BACKGROUND

Human embryo implantation is regulated by estradiol (E2), progesterone and locally produced mediators including interleukin-1beta (IL-1beta). Interactions between the estrogen receptor (ER) and NF kappa B (NFkappaB) signalling pathways have been reported in other systems but have not been detailed in human endometrium.

METHODS AND RESULTS

Real-time PCR showed that mRNA for the p65 and p105 NFkappaB subunits is maximally expressed in endometrium from the putative implantation window. Both subunits are localized in the endometrial epithelium throughout the menstrual cycle. Reporter assays for estrogen response element (ERE) activity were used to examine functional interactions between ER and NFkappaB in telomerase immortalized endometrial epithelial cells (TERT-EEC). E2 and IL-1beta treatment of TERT-EECs enhances ERE activity by a NFkappaB and ER dependent mechanism; this effect could be mediated by ERalpha or ERbeta. E2 and IL-1beta also positively interact to increase endogenous gene expression of prostaglandin E synthase and c-myc. This is a gene-dependent action as there is no additive effect on cyclin D1 or progesterone receptor expression.

CONCLUSION

In summary, we have established that NFkappaB signalling proteins are expressed in normal endometrium and report that IL-1beta can enhance the actions of E2 in a cell line derived from healthy endometrium. This mechanism may allow IL-1beta, possibly from the developing embryo, to modulate the function of the endometrial epithelium to promote successful implantation, for example by regulating prostaglandin production. Aberrations in the interaction between the ER and NFkappaB signalling pathways may have a negative impact on implantation contributing to pathologies such as early pregnancy loss and infertility.

Proteomics of embryonic implantation

Implantation is a complex process involving an intricate cascade of molecular interactions between the implanting blastocyst and the receptive endometrium. The molecular basis of endometrial receptivity and the mechanisms by which the blastocyst first adheres to the luminal epithelium and then penetrates into the stroma are only just beginning to be resolved. Advances in "omics" technologies, particularly proteomics and metabolomics, are set to have a major impact on the development of this field. In the wake of this information, novel targets for contraceptive intervention may become apparent.

Interleukin (IL)-1beta stimulates migration and survival of first-trimester villous cytotrophoblast cells through endometrial epithelial cell-derived IL-8

IL-1, secreted by human embryos and trophoblast cells, is important for successful implantation and pregnancy. We previously reported that IL-1beta induced IL-8 production in human endometrial stromal cells (ESCs) and that induction was regulated by substances implicated in implantation. In the present study using human primary cells in culture, we measured IL-1beta-induced production of IL-8 from endometrial epithelial cells (EECs) and ESCs and examined effects of the endometrium-derived IL-8 on migration and number of first-trimester villous cytotrophoblast cells (vCTs). Both basal and IL-1beta-induced IL-8 levels of cell supernatants were much higher in EECs than ESCs. Addition of IL-1beta to EECs increased the chemotactic activity of the supernatants to vCTs, and this effect was suppressed by immunoneutralization with anti-IL-8 antibody. Supernatants of IL-1beta-stimulated EECs yielded significantly higher number of vCTs compared with those of untreated EECs, and the effect was inhibited by IL-8 antibody. These findings suggest that IL-1 promotes implantation by stimulating EECs to produce IL-8, which subsequently induces migration of vCTs and contributes to survival of vCTs.

Stimulation of endometrium embryo transfer can improve implantation and pregnancy rates for patients undergoing assisted reproductive technology for the first time with a high-grade blastocyst

OBJECTIVE

To evaluate whether stimulation of endometrium embryo transfer (SEET) can improve implantation rate and pregnancy rate (PR) for patients undergoing assisted reproductive technology (ART) for the first time by injecting embryo culture supernatant into the uterus before blastocyst transfer (BT).

DESIGN

Randomized, controlled trial.

SETTING

Private in vitro fertilization clinic.

PATIENT(S)

Forty-eight women in the BT group, 48 women in the stimulation group who had culture medium injected into the uterus before BT, and 48 women in the SEET group.

INTERVENTION(S)

Injection of embryo culture supernatant and injection of culture medium.

MAIN OUTCOME MEASURE(S)

Implantation rates and PRs.

RESULT(S)

Odds ratios of successful implantation rate for stimulation and SEET in patients with high-grade blastocysts, having BT as reference, were 2.58 and 6.46 without adjustment, and 5.91 and 9.20 after adjusting for basal FSH levels and period of infertility. Odds ratios of clinical pregnancies were 2.47 and 4.32 without adjustment, and 4.46 and 5.10 with adjustment, respectively. In groups with low-grade blastocysts, such tendencies were not observed.

CONCLUSION(S)

The SEET may be an effective method for increasing implantation rate and PR for first-time ART patients who have a high-grade blastocyst.

The effects of sex steroid hormones and interleukin-1-beta on MUC1 expression in endometrial epithelial cell lines

Oestrogen, progesterone and paracrine signals from the embryo have been associated with the overall control of implantation. Changes in the expression of the heavily glycosylated transmembrane glycoprotein MUC1 mucin on the endometrial epithelium are also thought to be important for embryo attachment. Increased MUC1 expression has been correlated with elevated progesterone levels in the secretory phase of the menstrual cycle. Embryonic control of endometrial receptivity through changes in MUC1 expression could be achieved through the interleukin-1 system. Four endometrial epithelial cell lines (HEC1A, HEC1B, Ishikawa and RL592) were treated with oestrogen and progesterone (with or without interleukin-1-beta) and were subjected to immunocytochemistry and flow cytometric analysis to determine MUC1 production using MUC1 antibodies. HEC1A (oestrogen receptor (ER) and progesterone receptor (PR) positive) and HEC1B (ER positive and PR negative) were transfected with the MUC1 promoter, underwent similar treatment regimes and the activity of the MUC1 promoter relative to their untreated controls was determined using a chloramphenicol acetyltransferase (CAT) enzyme-linked immunoassay. Using the cell lines, we determined that endometrial MUC1 expression is up-regulated by progesterone, consistent with the in vivo increases in MUC1 related to high progesterone levels. We also revealed that neither oestrogen, nor interleukin-1-beta, appear to modulate MUC1. Progesterone-dependent regulation of MUC1 is likely to be an important factor in determining endometrial receptivity.

Cytokines, chemokines and growth factors in endometrium related to implantation

The complexity of the events of embryo implantation and placentation is exemplified by the number and range of cytokines with demonstrated roles in these processes. Disturbance of the normal expression or action of these cytokines results in complete or partial failure of implantation and abnormal placental formation in mice or humans. Of known importance are members of the gp130 family such as interleukin-11 (IL-11) and leukaemia inhibitory factor (LIF), the transforming growth factor beta (TGFbeta) superfamily including the activins, the colony-stimulating factors (CSF), the IL-1 system and IL-15 system. New data are also emerging for roles for a number of chemokines (chemoattractive cytokines) both in recruiting specific cohorts of leukocytes to implantation sites and in trophoblast differentiation and trafficking. This review focuses on those cytokines and chemokines whose expression pattern in the human endometrium is consistent with a potential role in implantation and placentation and for which some relevant actions are known. It examines what is known of their regulation and action along with alterations in clinically relevant situations.

Development, chromosomal composition, and cell allocation of bovine cloned blastocyst derived from chemically assisted enucleation and cultured in conditioned media

Treatment of in vitro matured bovine oocytes with colcemid results in a membrane protrusion that contains maternal chromosomes, which can be easily removed by aspiration. Four experiments were designed to evaluate the overall and temporal effects of conditioned medium (CM) by bovine cumulus cells on development of nuclear transfer (NT) bovine embryos and to examine the chromosomal composition and allocation of inner cell mass (ICM) and trophectoderm (TE) of the subsequent blastocysts. The nuclear transfer embryos were cultured in various CR1aa media conditioned by preculture with bovine cumulus cells. Development to the blastocyst stage in BSA-containing CM (BCM) and serum-containing CM (SCM) were similar to co-culture group (24-30%). The 24 hr-conditioned BCM yielded higher blastocyst development than 48 and 72 hr-conditioned BCM. Temporary exposure of embryos to BCM and SCM followed by CR1aa was also studied. Morula and blastocyst development were not different among the groups cultured in BCM for 72, 96, and 168 hr, but were significantly higher (P < 0.01) than groups exposed to BCM for 24 and 48 hr, respectively. Blastocyst development in SCM for 24 hr (29%), 96 hr (25%), and 168 hr (27%) were much higher (P < 0.05) than those in SCM for 48 hr (12%) and 72 hr (10%). The analyses of chromosomal composition of the resulting blastocysts indicate approximately 80% of the blastocysts cultured in CR1aa with co-culture or groups initially exposed to BCM for 24 hr followed by culture in CR1aa were diploid. However, the incidence of diploidy were only 36-60% in SCM-cultured groups and groups cultured in BCM beyond 48 hr. Conditioned media did not affect the allocation of ICM and TE in the blastocyst. No difference was found in the ratio of inner cell mass to total cells in co-culture, BCM or SCM groups (0.424, 0.441, and 0.473, respectively). In conclusion, bovine cumulus cell-CM and CR1aa with co-culture supported comparable development and blastocyst ICM:total cell ratio of bovine NT embryos. However, CM affected the blastocyst chromosomal composition and induced higher mixploidy.

Conditioned medium increases the polyploid cell composition of bovine somatic cell nuclear-transferred blastocysts

The effects of bovine cumulus cell-conditioned medium on cloned bovine embryonic development and subsequent chromosome complement were examined using an air-dry procedure. Conditioned media were prepared using CR1aa supplemented with either fetal bovine serum (FBS) or bovine serum albumin (BSA). Nuclear-transferred embryos were reconstructed with nuclei from cumulus cells. Similar cleavage, morula, and blastocyst development was observed in conditioned media groups compared with the co-culture group. No differences (P > 0.05) were observed in the composition of blastocyst chromosomes after co-culture in different media, either with or without starvation of donor cells. The overall diploid blastocyst rate ranged from 75% to 84%. Chromosomal complement of blastocysts, however, was very different between conditioned medium and co-culture treatments. Overall incidence of chromosomal anomalies was 40% in conditioned medium, which was significantly higher (P < 0.001) than the co-culture group (20%). Moreover, a higher incidence (P < 0.05) of chromosomally abnormal blastocysts (41.5%) was observed after culture with FBS-containing conditioned medium than those cultured in BSA-containing conditioned medium (31.4%). No diploid improvement was observed after exchange of the culture system from conditioned medium to co-culture, or from co-culture to conditioned medium after the first 72 h of culture. The results of this study also indicated that the overall cell number was much lower (P < 0.01) in blastocysts with chromosomal abnormalities than those with a normal diploid state. We have concluded that medium conditioned with bovine cumulus cells increases the incidence of chromosomal anomalies in nuclear reconstructed embryos.

Implantation: Embryonic Signals and the Modulation of the Uterine Environment—A Review

Interaction between maternal endometrium and embryo during implantation is mediated through the multiple molecules and signalling cascades, which are still not fully understood. This complex sequence of events results in the transformation of stromal cells into decidual cells (decidualization). The conceptus is essential to regulate these changes in baboon stromal fibroblasts, possibly through production of cytokines by the implanting embryo. The role of interleukin-1 (IL-1) system during implantation and its contribution to decidualization is discussed in this review. Decidualized endometrial stromal cells are thought to contribute to establishment of a successful pregnancy by expressing a number of gene products. One of the major products of decidual cells is insulin-like growth factor binding protein-1 (IGFBP-1). The IGFBP-1 serves as a modulator of insulin-like growth factor (IGF) protein action in the interactions between the decidua and invading trophoblast. The delineation of the mechanisms involved in cooperative action of transcription factors FKHR and HOXA10 leading to IGFBP-1 expression, as well as interrelationship between IL-1 and IGF signalling cascades will contribute to the understanding of events leading to successful implantation.

Biochemical evaluation of endometrial function at the time of implantation

OBJECTIVE

To review the literature on various endometrial factors assumed to be of importance to implantation and to evaluate their potential clinical value in the assessment of endometrial function at the time of implantation in infertile women in natural and stimulated cycles.

DESIGN

Literature review.

RESULT(S)

Cytokines such as leukemia inhibitory factor, colony-stimulating factor-1, and interleukin-1 have all been shown to play important roles in the cascade of events that leads to implantation. They participate in a synchronized cooperation between the endometrium and the preimplanting embryo under the influence of steroid hormones. The same applies to the integrin alpha(v)beta(3), glycodelin, and the polymorphic mucin 1. The usefulness of these factors to assess endometrial receptivity and to estimate the prognosis for pregnancy in natural and artificial cycles remains to be proven.

CONCLUSION(S)

The studies performed to date have mostly included only small groups of patients with a lack of fertile controls, and only a few prospective, controlled trials have been carried out. Therefore, definite conclusions about the clinical value of these factors in the assessment of endometrial function and prognosis for pregnancy after artificial reproductive therapy cannot be drawn at present. Further evaluation of their importance for and function during implantation is needed.

IL-1beta during in vitro decidualization in primate

The sequence of biochemical and molecular events associated with decidualization in the primate remain unclear. In the baboon, the sequential changes during this period in vivo are characterized by the downregulation of alpha-smooth actin followed by induction of cyclooxygenase-2 (COX-2) at the implantation site and the expression of insulin growth factor binding protein-1 (IGFBP-1). IGFBP-1 is the predominant protein in decidualized cells and is considered to be biochemical marker of decidualization. In the baboon the expression of IGFBP-1 requires the presence of a conceptus in vivo or N(6), 2'-O-dibutyryladenosine 3:5'-cyclic monophosphate (dbcAMP) in the presence of hormones in vitro. In addition IL-1beta, as a possible conceptus-mediated factor, can induce IGFBP-1 expression in the presence of hormones following 3 days of incubation. However, if IL-1beta and dbcAMP are added together, IGFBP-1 expression is inhibited which resulted in IL-1beta being considered to be "inhibitory" to decidualization. Current data suggest that IL-1beta can activate multiple signaling pathways that either positively (no exogenous cAMP) or negatively (in presence of exogenous cAMP) regulate IGFBP-1 gene expression and decidualization in vitro. Signaling pathways activated by IL-1beta following 10 min of stimulation result in the phosphorylation of mitogen-activated protein kinase (MAPK, specifically p38 MAPK) and also lead to NF-kappaB activation. The expression of COX-2 and matrix metalloproteinase-3 (MMP-3) genes follows after 4-6 h. The steroid hormones, particularly progesterone, which are critical for IGFBP-1 expression, modulate the activity of IL-1beta by down-regulating MMP-3 activity. Disruption of actin filaments enhances IGFBP-1 induction during decidualization. IL-1beta induced MMP-3 may upregulate IGFBP-1 by initiation of cytoskeletal reorganization through degradation of extracellular matrix (ECM). Inhibition of IL-1beta induced pathways leads to reduction of IGFBP-1 expression, suggesting that IL-1beta may be involved in the events leading to decidualization in baboons.

Gonadotropin-releasing hormone messenger ribonucleic acid and protein expression in Vero cells

PURPOSE

Interleukin-1 (IL-1) is a major regulator of local cellular interactions during embryonic implantation. We hypothesized that gonadotropin-releasing hormone (GnRH) may also play a role in the embryonic/epithelial dialogue during early implantation. To examine this hypothesis, we examined the ability of IL-1 to regulate GnRH mRNA and protein expression in Vero cells.

METHODS

Viable Vero cells (1 x 10(5)/well) were cultured in multiple-well tissue culture plates for in vitro studies and in 4-well chamber slides for immunohistochemical study. Confluent Vero cells were cultured with increasing concentrations of recombinant human IL-1 beta for an additional 24 hr. Vero cell expression of GnRH and GnRH receptor mRNAs was measured with polymerase chain reaction (PCR) and nested PCR, respectively. GnRH protein expression was validated by immunohistochemistry study. The quantitative level of GnRH mRNA expression regulated by IL-1 beta in Vero cells was determined by quantitative competitive PCR (QC PCR) with standard curve methodology.

RESULTS

RT-PCR revealed beta-actin, GnRH, and GnRH receptor mRNA expression in Vero cell cultures. Immunostaining confirmed the presence of GnRH protein in Vero cells. Quantitative PCR demonstrated IL-1 beta up-regulation of Vero cell GnRH mRNA expression (p < 0.05).

CONCLUSIONS

These results suggest that Vero cell mRNA and protein expression of GnRH may play a substantial role in early embryo/epithelial dialogue during embryo coculture, with an embryotrophic effect due to expression of GnRH by Vero cells.

Interleukin-6 levels in co-culture of human in vitro fertilization embryos with Vero cells are not predictive of future successful development

PROBLEM

In an attempt to predict successful embryo transfer and implantation, we measured interleukin (IL)-6 levels in culture supernatants of co-cultured preimplantation human embryos. We tested whether all in vitro fertilized human embryos in co-cultures do secrete IL-6, and whether there was any difference in such production between embryos that successfully reached the blastocyst stage and blocked embryos. We also addressed the question of IL-6 secretion by co-culture support cells, namely Vero cells themselves.

METHOD OF STUDY

Each fertilized oocyte was cultured individually and transferred in culture wells supplemented with a feeder layer of Vero cells at day 2. In vitro IL-6 production was measured by bioassay of the culture media.

RESULTS

Because Vero cells themselves secrete IL-6, it became impossible, in co-culture, to quantify production of IL-6 by the sole embryos. On the other hand, the co-culture technique has shown us that embryos are likely to consume IL-6. There was no difference between blastocysts and blocked embryos.

CONCLUSIONS

IL-6 levels in human embryo co-cultures do not correlate with future successful embryo transfer.

Regulation of preimplantation development of bovine embryos by interleukin-1beta

Experiments were performed to determine the actions of recombinant bovine interleukin-1beta (IL-1beta) on the growth of preimplantation embryos. In the first series of studies, IL-1beta was added at 8-10 h after insemination, and the percentage of oocytes developing to the blastocyst stage was evaluated. IL-1beta increased development to the blastocyst stage when embryos were cultured at high density ( approximately 25-30 embryos/drop) but decreased or had no effect on development when cultured at low density ( approximately 10 embryos/drop). Thus, the positive effect of IL-1beta depends upon some other embryo-derived product. The effect of IL-1beta on embryonic development was maintained in completely denuded embryos, indicating that cumulus cells do not mediate the actions of IL-1beta. Maximum development of embryos cultured at approximately 25-30/drop occurred at 0.1-1 ng/ml; 10 ng/ml was less effective. Addition of IL-1beta to groups of approximately 25-30 embryos/drop at 8-10 h after insemination also increased embryo cell number at Day 5 postinsemination by increasing the proportion of embryos that reached the 9- to 16-cell stage. However, IL-1beta had no effect on the proportion of blastocysts when added at Day 5 postinsemination. Thus, IL-1beta probably acts to increase blastocyst numbers by exerting actions on embryo growth before Day 5. In contrast to its effect on embryos, addition of IL-1beta during oocyte maturation did not affect cumulus expansion, cleavage rate of oocytes, or subsequent development to the blastocyst stage. In conclusion, IL-1beta can modulate growth of bovine embryos at early stages of development in a manner dependent upon embryo density.