Excessive intrauterine fluid cause aberrant implantation and pregnancy outcome in mice

The histone methyltransferase KMT2D is essential for embryo implantation via regulating precise differentiation of endometrial cells

Embryo implantation failures are a major challenge in reproductive medicine, but the underlying mechanism remains poorly understood. Successful implantation requires dynamic remodeling of the endometrium through integrated proliferation and differentiation of endometrial cells including luminal epithelial, glandular epithelial, and stromal cells. Conversely, their disruption causes infertility. Spatiotemporal control of transcription is required for these processes; however, the underlying epigenetic regulation is largely unknown. In this study, we examined expression data from the human endometrium during implantation and discovered that expression of the histone lysine methyltransferase KMT2D was significantly suppressed in patients with recurrent implantation failure. Further study revealed that uterine deletion of Kmt2d in mice caused infertility due to implantation failure. Morphological analysis discovered a reduction in the number of uterine glands and aberrant differentiation of the luminal and glandular epithelium into stratified phenotypes in Kmt2d knockout uteri. Administration of leukemia inhibitory factor protein, which is expressed in uterine glands and is essential for implantation, did not rescue implantation failure in Kmt2d knockout mice, suggesting that infertility was not solely due to uterine gland dysfunction. RNA sequencing analysis revealed that Kmt2d knockout uteri displayed suppressed expression of genes involved in ion homeostasis, which may affect the uterine luminal morphology. Our study suggests that KMT2D plays an essential role in facilitating successful embryo implantation by regulating the coordinated differentiation of endometrial cells, providing valuable insights into unexplained implantation failures in women.

Systematic review analyzing significance of endometrial cavity fluid during assisted reproductive techniques

OBJECTIVE

The objective of our study is to estimate the prevalence of endometrial cavity fluid (ECF) in Assisted Reproductive Techniques (ART) cycles and analyze its effects on pregnancy outcome in such cycles.

DATA SOURCES

PubMed, Cochrane Central, Scopus, and clinicaltrials.gov were searched for articles. The reference lists of relevant publications were explored for other studies.

STUDY ELIGIBILITY CRITERIA

Studies that had assessed the pregnancy outcome in ART cycles and had commented on ECF accumulation were included. Pregnancy outcomes were assessed in all ART cycles where ECF was observed and were compared to the non-ECF cycles.

RESULTS

A total of nine studies were included in the meta-analysis for a total of 28,210 cycles. Pooled analysis of the prevalence of ECF cycles out of total cycles in females undergoing ART using a fixed effect model showed that it was 14% (95% CI is 13% to 14%; I2 = 99%, p =  < 0.01). The random effect model prevalence of ECF cycles was around 7% (95% CI: 4% to 10%). There was a statistically significant (25%) decrease in pregnancy rates per cycle transfer in the ECF cycle versus the non-ECF cycle group during ART [OR = 0.75, 95% CI = 0.67-0.84), p < 0.001; moderate quality evidence]. When ECF size was compared, there was a statistically significant increase in pregnancy rates if ECF size was less than 3.5 mm versus greater than or equal to 3.5 mm [OR = 13.67, 95% CI = 1.43-130.40), p = 0.02; high quality evidence]. Sub-group analysis revealed that the ECF present at the time of embryo transfer significantly decreased the pregnancy rates by 26% as compared to the group where the ECF was not present at the time of embryo transfer [OR = 0.74, 95% CI = 0.65-0.85), p < 0.001].

CONCLUSIONS

This meta-analysis proposes that the presence of ECF significantly decreases the implantation and pregnancy rates of ART cycles, and even more so if its size is greater than 3.5 mm. Interventions to decrease ECF formation or treat it have enhanced the pregnancy outcome in ART cycles.

PROSPERO REGISTRATION

Date: 17th September 2020; Number: CRD42020182262.

Endometrial fluid biomarkers and their potential as predictors of successful embryo implantation

Background

Embryo implantation is a complex biological process which requires synchronized dialogue between the receptive endometrium and the blastocyst. The endometrium, however, is only receptive to embryo implantation for a very short period. Recurrent implantation failure (RIF) is a major challenge in assisted reproductive techniques mainly due to impaired receptivity, but there is still a need for a reliable and valid clinical test to assess endometrial receptiveness, especially at embryo transfer time. The aim of this review is to investigate what is currently known about the contribution of endometrial fluid (EF) to endometrial receptivity by identifying its potential biomarkers.

Methods

This study involved an extensive search of the electronic databases PubMed and Cochrane, covering the period from 2011 to 2022. A combination of Medical Subject Headings with the terms 'endometrial fluid' and 'embryo implantation' was used.

Results

Several different proteins presented in the endometrial cavity fluid have been described but the most consistent as potential biomarkers were Proprotein Convertase 6 (PC6), Vascular Endothelial Growth Factor (VEGF), PIGF (Placental growth factor), β3 integrin, Colony Stimulating Factor-3 (CSF-3), Leukaemia inhibitory factor (LIF), glycodelin and extracellular vesicles (EVs).

Conclusions

Strong indicators support the use of uterine fluid collection as a non-invasive tool for receptivity assessment. Therefore, it could improve outcomes of assisted reproductive techniques.

Visualization of preimplantation uterine fluid absorption in mice using Alexa Fluor™ 488 Hydrazide†

Uterine fluid plays important roles in supporting early pregnancy events and its timely absorption is critical for embryo implantation. In mice, its volume is maximum on day 0.5 post-coitum (D0.5) and approaches minimum upon embryo attachment ~D4.0. Its secretion and absorption in ovariectomized rodents were shown to be promoted by estrogen and progesterone (P4), respectively. The temporal mechanisms in preimplantation uterine fluid absorption remain to be elucidated. We have established an approach using intraluminally injected Alexa Fluor™ 488 Hydrazide (AH) in preimplantation control (RhoAf/f) and P4-deficient RhoAf/fPgrCre/+ mice. In control mice, bulk entry (seen as smeared cellular staining) via uterine luminal epithelium (LE) decreases from D0.5 to D3.5. In P4-deficient RhoAf/fPgrCre/+ mice, bulk entry on D0.5 and D3.5 is impaired. Exogenous P4 treatment on D1.5 and D2.5 increases bulk entry in D3.5 P4-deficient RhoAf/fPgrCre/+ LE, while progesterone receptor (PR) antagonist RU486 treatment on D1.5 and D2.5 diminishes bulk entry in D3.5 control LE. The abundance of autofluorescent apical fine dots, presumptively endocytic vesicles to reflect endocytosis, in the LE cells is generally increased from D0.5 to D3.5 but its regulation by exogenous P4 or RU486 is not obvious under our experimental setting. In the glandular epithelium (GE), bulk entry is rarely observed and green cellular dots do not show any consistent differences among all the investigated conditions. This study demonstrates the dominant role of LE but not GE, the temporal mechanisms of bulk entry and endocytosis in the LE, and the inhibitory effects of P4-deficiency and RU486 on bulk entry in the LE in preimplantation uterine fluid absorption.

Intrauterine Instillation of Human Chorionic Gonadotropin with Intrauterine Insemination Catheter Around the Golden Time of Embryo Transfer Does Not Improve In Vitro Fertilization /Intracytoplasmic Sperm Injection Outcomes in Infertile Women: A Randomized Controlled Trial

BACKGROUND

We set out to explore the effect of intrauterine human chorionic gonadotropin (hCG) instillation by intrauterine insemination (IUI) catheter before embryo transfer (ET) on assisted reproductive technologies (ART) outcomes of infertile women.

METHODS

One hundred women with infertility who were scheduled for in vitro fertilization (IVF)/intracytoplasmic sperm injection (ICSI) cycles were included in the study. They were randomly devoted to two groups: experimental (n= 50) and control (n= 50). In the experimental group, 500 IU hCG passed into the internal cervical orifice via IUI catheter within 15 minutes before the transfer of fresh or vitrified cleavage-stage embryos. The control group underwent the same ET procedure without prior injection of hCG.

RESULTS

None of the outcomes showed a statistically significant difference between the two groups. In the intervention and control groups, respectively, biochemical pregnancies rates were 26% and 18%, implantation rates were 13.5% and 8.6%, clinical pregnancies rates were 22% and 14%, ongoing pregnancies rates were 18% and 14%, and live birth rates were 14% and 12%.

CONCLUSION

Intrauterine injection of hCG via IUI catheter is not recommended in a clinical routine setting at this stage. Future efforts are warranted to further refine the applicability of this modality.

Intra-cavitary fluid resulted from caesarean section but not isthmocele compromised clinical pregnancy after IVF/ICSI treatment

The aim of this study was to explore whether the presence of intra-cavitary fluid (ICF) influences the pregnancy outcomes of patients with caesarean section (CS) in embryo transfer cycles. A total of 8494 transferred cycles of 4924 women were enrolled in this retrospective study and separated into three subgroups by previous delivery method and the presence of intra-cavity fluid, a caesarean group with ICF (CS-ICF, n = 649), a caesarean group without ICF (CS-noICF, n = 3207), and the remaining 4638 cycles without ICF were included in the vaginal delivered group (VD, n = 4638). Baseline characteristics and clinical outcome were compared. Propensity score matching (PSM) was conducted to adjust confounding factors between groups. Patients in the CS-ICF group were of younger age (36.49 ± 4.19 vs 37.34 ± 4.25, 37.32 ± 4.86, P < 0.001), had better ovary reserve, and had more blastocyst transferred compared with the CS-noICF and VD groups. However, cycles in the CS-ICF group achieved unsatisfactory clinical pregnancy outcomes. PSM analysis for comparability and differences in clinical outcomes still existed. The clinical pregnancy rate was significantly lower in the CS-ICF group than in the CS-noICF group (35.1% vs 41.7% for CS-noICF group, 48.1% for VD group, P < 0.001). Subgroup analysis of fresh embryo transferred cycles, the differences in clinical outcomes disappeared after PSM analysis, while the clinical pregnancy rate was still lowest among the three matched groups of FET cycles (36.4% vs 50.3% for VD group, P < 0.001). The presence of intra-cavitary fluid (ICF), but not necessarily the isthmocele, significantly compromises the clinical pregnancy rate in patients with previous CS undergoing IVF/ICSI treatment.

Endometrial fluid aspiration immediately prior to embryo transfer does not affect IVF/vitrified-warmed embryo transfer outcomes - a prospective matched cohort study

RESEARCH QUESTION

Does the endometrial aspiration of ultrasound-invisible fluid immediately preceding embryo transfer affect IVF/vitrified-warmed embryo transfer outcomes?

DESIGN

A prospective matched cohort study was conducted in 96 women and 96 control participants to assess the effect on pregnancy outcomes of endometrial aspiration performed immediately before embryo transfer. This study was carried out at a university-affiliated assisted reproductive medical centre between January 2019 and December 2019. Patients were divided into two groups. The EA group had cycles with endometrial aspiration of ultrasound-invisible fluid performed before embryo transfer and the non-EA group featured cycles without endometrial aspiration. The EA group was matched by propensity score with the non-EA group in a 1:1 ratio. The EA group consisted of 99 participants before and 96 participants after propensity score matching. There were 203 and 96 participants in the non-EA group before and after propensity score matching.

RESULTS

No significant differences were detected in the baseline characteristics and cycle characteristics of the EA and non-EA groups. No significant between-group differences were found in reproductive outcomes in the overall population. Subgroup analysis of blastocyst transfer cycles showed the implantation rate was significantly higher in the EA group (61 women per group, 57.1% versus 40.8%, relative risk 1.40, 95% confidence interval 1.04-1.88; P = 0.022). Live birth rate, clinical pregnancy rate, ongoing pregnancy rate and multiple pregnancy rate were not different among the groups.

CONCLUSIONS

Endometrial aspiration immediately preceding embryo transfer does not affect IVF/vitrified-warmed embryo transfer outcomes. Interestingly, it might improve the vitrified-warmed blastocyst implantation rate. Randomized controlled trials are needed to confirm this result.

Disruption of Folate Metabolism Causes Poor Alignment and Spacing of Mouse Conceptuses for Multiple Generations

Abnormal uptake or metabolism of folate increases risk of human pregnancy complications, though the mechanism is unclear. Here, we explore how defective folate metabolism influences early development by analysing mice with the hypomorphic Mtrr^gt mutation. MTRR is necessary for methyl group utilisation from folate metabolism, and the Mtrr^gt allele disrupts this process. We show that the spectrum of phenotypes previously observed in Mtrr^gt/gt conceptuses at embryonic day (E) 10.5 is apparent from E8.5 including developmental delay, congenital malformations, and placental phenotypes. Notably, we report misalignment of some Mtrr^gt conceptuses within their implantation sites from E6.5. The degree of misorientation occurs across a continuum, with the most severe form visible upon gross dissection. Additionally, some Mtrr^gt/gt conceptuses display twinning. Therefore, we implicate folate metabolism in blastocyst orientation and spacing at implantation. Skewed growth likely influences embryo development since developmental delay and heart malformations (but not defects in neural tube closure or trophoblast differentiation) associate with severe misalignment of Mtrr^gt/gt conceptuses. Typically, the uterus is thought to guide conceptus orientation. To investigate a uterine effect of the Mtrr^gt allele, we manipulate the maternal Mtrr genotype. Misaligned conceptuses were observed in litters of Mtrr^+/+, Mtrr^+/gt, and Mtrr^gt/gt mothers. While progesterone and/or BMP2 signalling might be disrupted, normal decidual morphology, patterning, and blood perfusion are evident at E6.5 regardless of conceptus orientation. These observations argue against a post-implantation uterine defect as a cause of conceptus misalignment. Since litters of Mtrr^+/+ mothers display conceptus misalignment, a grandparental effect is explored. Multigenerational phenotype inheritance is characteristic of the Mtrr^gt model, though the mechanism remains unclear. Genetic pedigree analysis reveals that severe conceptus skewing associates with the Mtrr genotype of either maternal grandparent. Moreover, the presence of conceptus skewing after embryo transfer into a control uterus indicates that misalignment is independent of the peri- and/or post-implantation uterus and instead is likely attributed to an embryonic mechanism that is epigenetically inherited. Overall, our data indicates that abnormal folate metabolism influences conceptus orientation over multiple generations with implications for subsequent development. This study casts light on the complex role of folate metabolism during development beyond a direct maternal effect.

GLUT4 in Mouse Endometrial Epithelium: Roles in Embryonic Development and Implantation

GLUT4 is involved in rapid glucose uptake among various kinds of cells to contribute to glucose homeostasis. Prior data have reported that aberrant glucose metabolism by GLUT4 dysfunction in the uterus could be responsible for infertility and increased miscarriage. However, the expression and precise functions of GLUT4 in the endometrium under physiological conditions remain unknown or controversial. In this study, we observed that GLUT4 exhibits a spatiotemporal expression in mouse uterus on pregnant days 1–4; its expression especially increased on pregnant day 4 during the window of implantation. We also determined that estrogen, in conjunction with progesterone, promotes the expression of GLUT4 in the endometrial epithelium in vivo or in vitro. GLUT4 is an important transporter that mediates glucose transport in endometrial epithelial cells (EECs) in vitro or in vivo. In vitro, glucose uptake decreased in mouse EECs when the cells were treated with GLUT4 small interfering RNA (siRNA). In vivo, the injection of GLUT4-siRNA into one side of the mouse uterine horns resulted in an increased glucose concentration in the uterine fluid on pregnant day 4, although it was still lower than in blood, and impaired endometrial receptivity by inhibiting pinopode formation and the expressions of leukemia inhibitory factor (LIF) and integrin ανβ3, finally affecting embryonic development and implantation. Overall, the obtained results indicate that GLUT4 in the endometrial epithelium affects embryo development by altering glucose concentration in the uterine fluid. It can also affect implantation by impairing endometrial receptivity due to dysfunction of GLUT4.

Endometrial cavity fluid is associated with deleterious pregnancy outcomes in patients undergoing in vitro fertilization/intracytoplasmic sperm injection: a retrospective cohort study

Background

The effects of endometrial cavity fluid (ECF) on in vitro fertilization (IVF) and intracytoplasmic sperm injection (ICSI) pregnancy outcomes following embryo transfer (ET) are still controversial. We conducted the present study to investigate whether the presence of ECF in infertile patients scheduled to undergo IVF or ICSI was associated with pregnancy outcomes.

Methods

A retrospective cohort study design was used. Among infertile patients undergoing IVF/ICSI, those with and without ECF were matched 1:1 using propensity score matching (PSM). After ensuring that the baseline levels of the two matched groups were consistent, the pregnancy and obstetrical outcomes of the two groups were compared.

Results

Patients with ECF had significantly lower clinical rates of pregnancy (1,061/1,862, 57% vs. 1,182/1,862, 63.5%; P<0.001), live birth (902/1,862, 48.4% vs. 1,033/1,862, 55.5%; P<0.001), biochemical pregnancy (1,182/1,862, 63.5% vs. 1,288/1,862, 69.2%; P<0.001), and embryo implantation (1,500/3,740, 40.1% vs. 1,661/3,740, 44.4%, P<0.001) than patients without ECF. Also, patients with ECF had a higher incidence of gestational diabetes (17/78, 22% vs. 8/94, 9%, P=0.014). However, there were no differences in gestational weeks at delivery or birth weight between the two groups.

Conclusions

ECF was significantly associated with adverse pregnancy outcomes but showed no significant association with adverse obstetric outcomes (except for gestational diabetes).

Effects of three abnormal conditions of fallopian tube on outcomes of the in vitro fertilization and embryo transfer technique

AIM

The aim of this study was to demonstrate whether salpingitis affects the outcomes of in vitro fertilization and embryo transfer (IVF-ET).

METHODS

The retrospective study includes patients from 2013 to 2018 who received their first IVF-ET treatment during this period. On the basis of their tubal conditions, the patients were subgrouped as: hydrosalpinx (group A), salpingitis (group B), tubal occlusion (group C). It had a total of 726 cycles, of which 208 cycles were in group A, 201 cycles in group B and 317 cycles in group C. The outcomes of the IVF-ET treatment were compared amongst the three groups.

RESULTS

Group C had the highest number of retrieved oocytes as compared to the groups A and B, and the rate of the high-quality embryos at day 3 (66-68 h after insemination) was higher in the groups C and A compared to the group B. The blastocyst formation rate was significantly higher in group C compared to that of the group B. Group C had higher rates of implantation, clinical pregnancy and live birth compared to both groups A and B, while the birth weight of newborns did not differ amongst the three groups.

CONCLUSION

Salpingitis has adverse effects on the success rate of the IVF-ET treatment, exemplified by lower implantation, clinical pregnancy and live birth rates compared to tubal occlusion, it may be necessary to carry out appropriate management of salpingitis before IVF-ET treatment.

Metabolic Changes of Maternal Uterine Fluid, Uterus, and Plasma during the Peri-implantation Period of Early Pregnancy in Mice

Embryo implantation is a complex process which involves biochemical and physiological interactions between an implantation-competent blastocyst and a receptive uterus. However, the exact biochemical changes of uterine fluid, uterus, and plasma during peri-implantation remain unclear. This study aims to characterize the biochemical and metabolic changes that occur during the peri-implantation period of early pregnancy, using mice as an animal model. Gas chromatography-mass spectrometry was used to analyze the metabolite profiles of the uterus, uterine fluid, and maternal plasma at pre-implantation and implantation. The multivariate analyses, ANOVA and Tukey's HSD test, were applied to detect significant changes in metabolites and metabolic pathways. The metabolic networks were reconstructed in silico based on the identified metabolites and KEGG metabolic framework. Between pre-implantation day 1 and day 4, dramatic metabolic changes were observed in the uterine fluid that could be important for blastocyst development and protection against the harsh uterine environment. Palmitoleic acid, fumaric acid, and glutaric acid changed levels at day 4 in the uterus, suggesting that they may be associated with endometrial receptivity. Both the uterus and maternal plasma showed profound changes in cellular metabolism at the early implantation period, including upregulation of branched-chain amino acids and intermediates of one-carbon metabolism, an upregulation of glyoxylate and dicarboxylate metabolism, and downregulation of aerobic respiration; all of which could be involved in the regulation of the maternal-fetal interface, alternative nutrient utilization, and energy preservation for implantation as well as later placentation and fetal development to ensure successful embryo implantation.

Investigating the Optimal Time for Intrauterine Human Chorionic Gonadotropin Infusion in Order to Improve IVF Outcome: A Systematic Review and Meta-Analysis

BACKGROUND/AIM

Studies on the impact of intrauterine human Chorionic Gonadotropin (hCG) administration in order to improve the In Vitro Fertilization (IVF) outcome have yielded conflicting results. The aim of the present systematic review and meta-analysis is to investigate whether timing of intrauterine hCG administration prior to embryo transfer affects its efficiency.

MATERIALS AND METHODS

A systematic search of the literature on Pubmed/Medline, Embase and Cochrane databases was performed. Only Randomized Control Trials were included in this meta-analysis.

RESULTS

Live birth rates were not improved following hCG administration (RR=1.13, 95%CI=0.88-1.46, p=0.34) in the pooled results. Combined live birth and ongoing pregnancy rates were borderline statistically significant following hCG administration (RR=1.27, 95%CI=1.00-1.62, p=0.05). Following subgroup analysis regarding live birth and ongoing pregnancy rates, only the 5-12 minutes prior to the embryo transfer group reported a statistically significant improvement.

CONCLUSION

Intrauterine infusion of hCG within an IVF-Intracytoplasmic Sperm Injection (ICSI) cycle improves outcome only when administered 5-12 min prior to embryo transfer.

New Insights into the Process of Placentation and the Role of Oxidative Uterine Microenvironment

For a successful pregnancy to occur, a predecidualized receptive endometrium must be invaded by placental differentiated cells (extravillous trophoblast cells (EVTs)) and, at the same time, continue decidualization. EVT invasion is aimed at anchoring the placenta to the maternal uterus and ensuring local blood supply increase necessary to provide normal placental and foetal development. The first is achieved by migrating through the maternal endometrium and deeper into the myometrium, while the second by transforming uterine spiral arteries into large vessels. This process is a tightly regulated battle comprising interests of both the mother and the foetus. Invading EVTs are required to perform a scope of functions: move, adhere, proliferate, differentiate, interact, and digest the extracellular matrix (ECM); tolerate hypoxia; transform the maternal spiral arteries; and die by apoptosis. All these functions are modulated by their surrounding microenvironment: oxygen, soluble factors (e.g., cytokines, growth factors, and hormones), ECM proteins, and reactive oxygen species. A deeper comprehension of oxidative uterine microenvironment contribution to trophoblast function will be addressed in this review.

Treatment of hydrosalpinx in relation to IVF outcome: a systematic review and meta-analysis

Salpingectomy is the most widely used treatment for hydrosalpinx. The effect of salpingectomy on the stimulation response during subsequent IVF treatment, however, remains unclear. The aim of this systematic review was to evaluate the ovarian response and pregnancy outcome of IVF treatment carried out after salpingectomy compared with other pre-IVF treatment options for hydrosalpinx. We conducted a literature search using PubMed, Ovid MEDLINE, Google Scholar, ClinicalTrials.gov and the Cochrane Central Register of Controlled Trials. Five randomized studies and nine observational studies were included in the systematic review and evaluated using Cochrane Collaboration's tool for randomized, Newcastle-Ottawa scale for observational studies and GRADE guidelines for certainty of evidence assessment. The mean number of retrieved oocytes was similar between the groups in randomized (mean difference [MD] = -0.03, 95% CI -0.75 to 0.70) and observational studies (MD = -0.15, 95% CI -2.32 to 2.02). Live birth (RR 1.59, 95% CI 1.17 to 2.16), clinical pregnancy (RR 1.27, 95% CI 1.02 to 1.57) and implantation rates (RR 1.55, 95% CI 1.16 to 2.08) were higher in the salpingectomy group in randomized studies. The present systematic review and meta-analysis showed that salpingectomy does not impair the ovarian response during subsequent IVF treatment.

Combinatorial effects of quercetin and sex-steroids on fluid and electrolytes' (Na+, Cl-, HCO3-) secretory mechanisms in the uterus of ovariectomised female Sprague-Dawley rats

Dysregulation of uterine fluid environment could impair successful reproduction and this could be due to the effect of environmental estrogens. Therefore, in this study, effect of quercetin, an environmental estrogen on uterine fluid and electrolytes concentrations were investigated under sex-steroid influence. Ovariectomised adult female Sprague-Dawley rats were given 10, 50 or 100mg/kg/day quercetin subcutaneously with 17-β estradiol (E) for seven days or three days E, then three days E plus progesterone (P) (E+P) treatment. Uterine fluid secretion rate, Na⁺, Cl^- and HCO₃^- concentrations were determined by in-vivo perfusion. Following sacrifice, uteri were harvested and levels of the proteins of interest were identified by Western blotting and Realtime PCR. Distribution of these proteins in the uterus was observed by immunofluorescence. Levels of uterine cAMP were measured by enzyme-linked immunoassay (EIA). Administration of quercetin at increasing doses increased uterine fluid secretion rate, Na⁺, Cl^- and HCO₃^- concentrations, but to the levels lesser than that of E. In concordant, levels of CFTR, SLC4A4, ENaC (α, β and γ), Na⁺/K⁺-ATPase, GPα/β, AC and cAMP in the uterus increased following increased in the doses of quercetin. Co-administration of quercetin with E caused uterine fluid secretion rate, Na⁺, Cl^- and HCO₃^- concentrations to decrease. In concordant, uterine CFTR, SLC26A6, SLC4A4, ENaC (α, β and γ), Na⁺/K⁺-ATPase, GPα/β, AC and cAMP decreased. Greatest effects were observed following co-administration of 10mg/kg/day quercetin with E. Co-administration of quercetin with E+P caused uterine fluid Na⁺ and HCO₃^- concentrations to increase but no changes in fluid secretion rate and Cl^- concentration were observed. Co-administration of high dose quercetin (100 mg/kg/day) with E+P caused uterine CFTR, SLC26A6, AC, GPα/β and ENaC (α, β and γ) to increase. Quercetin-induced changes in the uterine fluid secretion rate and electrolytes concentrations could potentially affect the uterine reproductive functions under female sex-steroid influence.

Short communication: Repeat breeder cows with fluid in the uterine lumen had poorer fertility

The objective of the present study was to test the association between the presence of fluid in uterine lumen and the fertility of repeat breeder cows (RBC). Grazing Holstein cows that were clinically normal and were not pregnant after at least 3 consecutive inseminations were defined as RBC and included in the study (n = 358). A cut-point ≥2 mm of uterine lumen visible by ultrasonography was used as indicative of the presence of fluid in the uterus. The effect of this fluid on the fertility of RBC was assessed by mixed logistic regression. Twenty percent of the RBC had ≥2 mm of fluid in their uterus, and this finding was associated with a marked reduction in the odds of conception (odds ratio = 0.46). Additional intrauterine sampling revealed that 24.0% of RBC showed signs of subclinical endometritis [≥5% neutrophils in endometrial cytology (SCE)]. However, we found no agreement between the finding of uterine fluid and the diagnosis of SCE (kappa coefficient = 0.03, 95% confidence interval = -0.07 to 0.14). In conclusion, the presence of fluid (≥2 mm) in uterine lumen, detected by ultrasonography, was associated with lower fertility in RBC, but was not related to the diagnosis of SCE. Thus, ultrasonographic evaluation is an important tool to assist in assessment of RBC.

A High-Throughput Assay for the Detection of α-Dystroglycan N-Terminus in Human Uterine Fluid to Determine Uterine Receptivity

Embryo implantation requires a healthy embryo and a receptive uterus. In women, the uterus remains a hostile environment and must undergo functional changes to convert to a receptive state for embryo implantation. Determining uterine receptivity is vital in IVF treatment, as the timing of embryo transfer needs to be synchronized with uterine receptivity. However, to date, no reliable biochemical tests are available to determine uterine receptivity. We recently established that removal of α-dystroglycan N-terminus (α-DG-N) from the uterine surface plays an important role in the establishment of uterine receptivity. Importantly, the α-DG-N removed from the uterine tissue enters into the uterine fluid, and the levels correlate with the tissue status of receptivity. Detection of α-DG-N in uterine fluid may therefore provide a nonsurgical approach to assess uterine receptivity. In this study, we first validated three monoclonal antibodies raised against α-DG-N in our system, and then established a sandwich ELISA suitable for the detection of α-DG-N in human uterine fluid. This ELISA detected significantly higher concentrations of α-DG-N in uterine fluid of women in the receptive phase. We believe this newly established α-DG-N ELISA may provide an important tool in the development of noninvasive strategies to detect uterine receptivity in women.