Glycosphingolipids of rabbit endometrium and their changes during pregnancy

Prospective evaluation of uterine receptivity in mice

In current infertility treatments it is necessary to evaluate uterine receptivity in each menstrual cycle. During the implantation period, the uterus goes through many complex orchestrated changes, including changes to the glycocalyx. The changes to the glycocalyx are due to sialylation, sulfation and fucosylation. Can the measurement of in-vivo uterine pH and/or oxidation-reduction potential (ORP) determine the alterations of uterine endometrium for implantation and evaluate prospective uterine receptivity? In the present study we assessed in vivo uterine pH and ORP during the early stages of pregnancy in naïve mice, as well as in a murine model of implantation failure created by local and transient suppression of signal transducer and activator of transcription 3. There was no change in the in vivo uterine pH between post-coitus Days 2 and 6. In vivo uterine ORP was significantly higher compared to the day before. One day before implantation began, uterine ORP was significantly decreased in the implantation failure group compared with the naïve and control groups. Receiver operator characteristic (ROC) curve analysis of uterine ORP as a predictor of non-conception showed an area under the ROC curve of 0.96 (95% confidence interval 0.92-1.00). Thus, in vivo uterine ORP could be a parameter to prospectively evaluate uterine receptivity.

Vaginal bioelectrical impedance determines uterine receptivity in mice

STUDY QUESTION

Can vaginal bioelectrical impedance (VZ) electrophysiologically determine alterations of the endometrium in preparation for implantation?

SUMMARY ANSWER

VZ can electrophysiologically detect the sulfation and sialylation changes in the uterine glycocalyx in preparation for implantation.

WHAT IS KNOWN ALREADY

Uterine receptivity is associated with various glycosylation changes that affect negative charge density at the luminal epithelial cell surface. VZ has been used to monitor the oestrous cycle.

STUDY DESIGN, SIZE, DURATION

Pathogen-free Jcl:ICR mice, aged 8-10 weeks, were used in this study. We conducted the following three steps to test our hypothesis that VZ may be used to determine uterine receptivity. First, to investigate whether VZ could determine alteration of sulfation and sialylation in the uterine glycocalyx, VZ was measured in mice with induced artificial sulfation and sialylation changes in the uterine glycocalyx (galactose-3-O-sulfotransferase 2 (GP3ST) + α(1,3/1,4) fucosyltransferase gene (FucT-III)-transferred group (n = 15) and in LacZ (encoding for β-galactosidase)-transferred mice as a control group (n = 12)). Second, to investigate whether VZ could determine alterations of the endometrium in preparation for implantation, we measured VZ during the early stage of pregnancy (n = 12 each). Third, to investigate whether VZ could be used to evaluate uterine receptivity prospectively, VZ was measured in an implantation failure model mice. In 21 mice, local and transient suppression of signal transducer and activator of transcription-3 (Stat3) in the uterus were evaluated 1 day before implantation began, and 23 scramble decoy-transferred mice were used as a control group.

PARTICIPANTS/MATERIALS, SETTING, METHODS

The VZ was measured at a frequency of 1 kHz in Jcl:ICR mice. Data were analysed using the Kruskal-Wallis test with Dunn's multiple comparisons, or the Student's t-test or Wilcoxon's rank-sum test with the Shapiro-Wilk normality test. The values of VZ were analysed using receiver operating characteristic (ROC) curve analysis to identify the optimal cut-off point to determine if this parameter predicted non-pregnancy.

MAIN RESULTS AND THE ROLE OF CHANCE

Sulfation and sialylation changes induced in the luminal epithelial glycocalyx decreased the value of VZ. VZ showed a significant daily decrease during the early stage of pregnancy (Day 1.5 versus 2.5 p.c.: P < 0.005; Student's t-test, Day 2.5 versus 3.5 p.c.: P < 0.001; Wilcoxon's rank-sum test, Day 3.5 versus 4.5 p.c.: P < 0.005; Student's t-test, Day 4.5 versus 5.5 p.c.: P < 0.05; Student's t-test). One day before implantation began, VZ in the implantation failure model mice was significantly higher than in the control mice (P < 0.001, Wilcoxon's rank-sum test). The ROC curve analysis of VZ as a predictor of non-conception showed areas under the ROC curve of 0.91 (95% CI: 0.83-0.99).

LIMITATIONS, REASONS FOR CAUTION

Although it is influenced by surface charge in the uterine epithelium, the mechanism whereby VZ changes during early pregnancy is still unexplained.

WIDER IMPLICATIONS OF THE FINDINGS

Local bioelectrical impedance may help to prospectively evaluate uterine receptivity in women. Including the measurement of local bioelectrical impedance as part of a frozen-thawed embryo transfer strategy may improve the efficiency of ART.

STUDY FUNDING/COMPETING INTEREST(S)

This work was supported in part by the Japan Society for the Promotion of Science JSPS KAKENHI Grant (Nos. 19390429, 21390453, 16K11086 and 16K11087) from the Ministry of Education, Science and Culture of Japan (Tokyo, Japan) and Suzuken Memorial Foundation (Nagoya, Japan). The authors declare that they have no conflict of interest.

Prediction of pregnancy after frozen-thawed embryo transfer via in vivo intrauterine oxidation-reduction potential measurements: a pilot study

PURPOSE

During the implantation period, the uterus goes through many complex, orchestrated changes, including alterations of the glycocalyx that are due to sialylation, sulfation, and fucosylation. A previous mouse study showed that the in vivo intrauterine oxidation-reduction potential (ORP) aided in determining the alterations in the uterine endometrium that are suitable for implantation and for evaluating prospective uterine receptivity, while the in vivo intrauterine pH did not. It was assessed if the in vivo intrauterine ORP could be a useful parameter to predict pregnancy in women.

METHODS

A prospective cohort study was conducted for patients who had received a frozen-thawed single embryo transfer in a programmed, hormonally controlled cycle. The in vivo intrauterine ORP was measured 3 times during the treatment cycle, at cycle days 9-10, 1 day before progesterone administration and immediately before the embryo transfer.

RESULTS

The amount of in vivo intrauterine ORP at 9-10 days after the start of menstrual bleeding was significantly lower in the pregnant group than in the non-pregnant group. A receiver-operator characteristic curve analysis of the intrauterine ORP as a predictor of non-conception showed an area under the curve of 0.80.

CONCLUSION

The in vivo intrauterine ORP could be a useful parameter to predict pregnancy for the frozen-thawed embryo transfer treatment cycle.

Carbohydrate to carbohydrate interaction in development process and cancer progression

Two types of carbohydrate to carbohydrate interaction (CCI) have been known to be involved in biological processes. One is the CCI between molecules expressed on interfacing cell membranes of different cells to mediate cell to cell adhesion, and subsequently induce cell signaling, and is termed trans-CCI. It has been indicated that the Le(x) to Le(x) interaction at the morula stage in mouse embryos plays an important role in the compaction process in embryonic development. GM3 to Gg3 or GM3 to LacCer interaction has been suggested to be involved in adhesion of tumor cells to endothelial cells, which is considered a crucial step in tumor metastasis. The other is the CCI between molecules expressed within the same microdomain of the cell surface membrane, and is termed cis-CCI. The interaction between ganglioside GM3, and multi (>3) GlcNAc termini of N-linked glycans of epidermal growth factor receptor (EGFR), has been indicated as the molecular mechanism for the inhibitory effect of GM3 on EGFR activation. Also, the complex with GM3 and GM2 has been shown to inhibit the activation of hepatocyte growth factor (HGF) receptor, cMet, through its association with tetraspanin CD82, and results in the inhibition of cell motility. Since CCI research is still limited, more examples of CCI in biological processes in development, and cancer progression will be revealed in the future.

Differential expression of gangliosides in the ovary and uterus of streptozotocin-induced and db/db diabetic mice

Gangliosides are widely distributed in mammalian cells and play important roles in various functions such as cell differentiation and growth control. In addition, diabetes and obesity cause abnormal development of reproductive processes in a variety of species. However, the mechanisms underlying these effects, and how they are related, are not fully understood. This study examined whether the differential expression of gangliosides is implicated in the abnormal follicular development and uterine architecture of streptozotocin (STZ)-induced and db/db diabetic mice. Based upon the mobility on high-performance thin-layer chromatography, mouse ovary consisted of at least five different ganglioside components, mainly gangliosides GM3, GM1, GD1a and GT1b, and diabetic ovary exhibited a significant reduction in ganglioside expression with apparent changes in the major gangliosides. A prominent immunofluorescence microscopy showed a dramatic loss of ganglioside GD1a expression in the primary, secondary and Graafian follicles of STZ-induced and db/db diabetic mice. A significant decrease in ganglioside GD3 expression was also observed in the ovary of db/db mice. In the uterus of STZ-induced diabetic mice, expression of gangliosides GD1a and GT1b was obviously reduced, but gangliosides GM1, GM2 and GD3 expression was increased. In contrast, the uterus of db/db mice showed a significant increase in gangliosides GM1, GD1a and GD3 expression. Taken together, a complex pattern of ganglioside expression was seen in the ovary and uterus of normoglycemic ICR and db/+ mice, and the correspoding tissues in diabetic mice are characterized by appreciable changes of the major ganglioside expression. These results suggest that alterations in ganglioside expression caused by diabetes mellitus may be implicated in abnormal ovarian development and uterine structure.

A mannose-binding glycoprotein found in the 4 day post coital rat uterus is involved in pregnancy

Experiments were conducted to study the functional implication of a mannose-binding glycoprotein found in the day 4 post coital (p.c.) rat uterus, using a mono-specific polyclonal antibody raised against the glycoprotein. Western Blot and immunohistochemical techniques were employed to study the distribution of the glycoprotein, and the results suggest that this glycoprotein is present only in the day 4 p.c. uterus and is specifically localized in the stromal cells. Administration of anti-UA (Uterine Agglutinin) antiserum against the glycoprotein into the day 4 p.c. uterine lumen inhibits carrying of embryo to term. The antiserum is not embryo toxic. After in vivo in utero intra-luminal administration of anti-UA antiserum in day 4 p.c. rat the antiserum has been specifically localized in the uterine stroma by immunohistochemistry. After intravenous injection, the glycoprotein is cleared mainly through the kidney and liver. The possible role of this glycoprotein in the implantation process in rats has been discussed. From the data it is evident that UA may not be directly involved in sugar-sugar interactions with embryo since it is not present in any significant amount in pregnant uterus from day 5 onwards. Since other experiments show that UA does have some role to play in early pregnancy, UA probably acts through some other factor, and preliminary studies suggest that this factor maybe TGF-beta3.