Mode Switch of Ca2 + Oscillation-Mediated Uterine Peristalsis and Associated Embryo Implantation Impairments in Mouse Adenomyosis

Improvement of early miscarriage rates in women with adenomyosis via oxytocin receptor antagonist during frozen embryo transfer-a propensity score-matched study

BACKGROUND

Dysfunctional uterine peristalsis seems to play a pivotal role in hindering embryo implantation among women diagnosed with adenomyosis. This research aims to investigate whether administering an oxytocin receptor antagonist during a frozen embryo transfer (FET) cycle using a hormone replacement therapy (HRT) protocol can enhance in vitro fertilization (IVF) outcomes for infertile women affected by adenomyosis.

METHODS

Between January 2018 and June 2022, our reproductive center conducted IVF-FET HRT cycles for infertile women diagnosed with adenomyosis. Propensity score matching was employed to select matched subjects between the two groups in a 1:1 ratio. Following this, 168 women received an oxytocin receptor antagonist during FET, constituting the study group, while the matched 168 women underwent FET without this antagonist, forming the control group. We conducted comparative analyses of baseline and cycle characteristics between the two groups, along with additional subgroup analyses.

RESULTS

The study group exhibited notably lower rates of early miscarriage compared to the control group, although there were no significant differences in clinical pregnancy rates, ongoing pregnancy rates, and live birth rates between the two groups. Multivariate analysis revealed a negative correlation between the use of oxytocin receptor antagonists and early miscarriage rates in women with adenomyosis. Subgroup analyses, categorized by age, infertility types, and embryo transfer day, showed a substantial decrease in early miscarriage rates within specific subgroups: women aged ≥ 37 years, those with secondary infertility, and individuals undergoing day 3 embryo transfers in the study group compared to the control group. Furthermore, subgroup analysis based on adenomyosis types indicated significantly higher clinical pregnancy rates, ongoing pregnancy rates and live birth rates in the study group compared to the control group among women with diffuse adenomyosis.

CONCLUSIONS

Administering an oxytocin receptor antagonist during FET may reduce the early miscarriage rates in women with adenomyosis.

Imaging the dynamics of murine uterine contractions in early pregnancy†

Uterine muscle contractility is essential for reproductive processes including sperm and embryo transport, and during the uterine cycle to remove menstrual effluent. Even still, uterine contractions have primarily been studied in the context of preterm labor. This is partly due to a lack of methods for studying the uterine muscle contractility in the intact organ. Here, we describe an imaging-based method to evaluate mouse uterine contractility of both the longitudinal and circular muscles in the cycling stages and in early pregnancy. By transforming the image-based data into three-dimensional spatiotemporal contractility maps, we calculate waveform characteristics of muscle contractions, including amplitude, frequency, wavelength, and velocity. We report that the native organ is highly contractile during the progesterone-dominant diestrus stage of the cycle when compared to the estrogen-dominant proestrus and estrus stages. We also observed that during the first phase of uterine embryo movement when clustered embryos move toward the middle of the uterine horn, contractions are dynamic and non-uniform between different segments of the uterine horn. In the second phase of embryo movement, contractions are more uniform and rhythmic throughout the uterine horn. Finally, in Lpar3-/- uteri, which display faster embryo movement, we observe global and regional increases in contractility. Our method provides a means to understand the wave characteristics of uterine smooth muscle in response to modulators and in genetic mutants. Better understanding uterine contractility in the early pregnancy stages is critical for the advancement of artificial reproductive technologies and a possibility of modulating embryo movement during clinical embryo transfers.

Phenanthroline relaxes uterine contractions induced by diverse contractile agents by decreasing cytosolic calcium concentration

Uterine contractions during labor and preterm labor are influenced by a complex interplay of factors, including hormones and inflammatory mediators. This complexity may contribute to the limited efficacy of current tocolytics for preterm labor, a significant challenge in obstetrics with 15 million cases annually and approximately 1 million resulting deaths worldwide. We have previously shown that the myometrium expresses bitter taste receptors (TAS2Rs) and that their activation leads to uterine relaxation. Here, we investigated whether the selective TAS2R5 agonist phenanthroline can induce relaxation across a spectrum of human uterine contractions and whether the underlying mechanism involves changes in intracellular Ca2+ signaling. We performed experiments using samples from pregnant women undergoing scheduled cesarean delivery, assessing responses to various inflammatory mediators and oxytocin with and without phenanthroline. Our results showed that phenanthroline concentration-dependently inhibited contractions induced by PGF2α, U46619, 5-HT, endothelin-1 and oxytocin. Furthermore, in hTERT-infected human myometrial cells exposed to uterotonics, phenanthroline effectively suppressed the increase in intracellular Ca2+ concentration induced by PGF2α, U46619, oxytocin, and endothelin-1. These results suggest that the selective TAS2R5 agonist may not only significantly reduce uterine contractions but also decrease intracellular Ca2+ levels. This study highlights the potential development of TAS2R5 agonists as a new class of uterine relaxants, providing a novel avenue for improving the management of preterm labor.

Reduced fertility in an adenomyosis mouse model is associated with an altered immune profile in the uterus during the implantation period

STUDY QUESTION

Does a reduction in fertility and/or systemic immune cell change occur during the early implantation period in a mouse model of adenomyosis?

SUMMARY ANSWER

A reduction in fertility was observed in mice with adenomyosis, coinciding with local and systemic immune changes observed during the implantation period.

WHAT IS KNOWN ALREADY

Adenomyosis is a pathology responsible for impaired fertility in humans, with a still unclear pathophysiology. One hypothesis is that changes in immune cells observed in adenomyosis-affected uteri may alter fertility, notably the physiological immune environment necessary for successful implantation and a healthy pregnancy.

STUDY DESIGN, SIZE, DURATION

Randomly selected CD-1 female neonatal pups were orally dosed by administration of tamoxifen to induce adenomyosis (TAM group), while others received solvent only (control group). From 6 weeks of life, CD-1 mice of both groups were mated to study impaired fertility and related local and/or systemic immune cell changes during the early implantation period.

PARTICIPANTS/MATERIALS, SETTINGS, METHODS

To evaluate fertility and pregnancy outcomes, ultrasound imaging was performed at E (embryonic day) 7.5 and E11.5 to count the number of gestational sacs and the number of resorptions in eight mice of the TAM group and 16 mice of the control group. The mice were sacrificed at E18.5, and morphometric, functional (quantitative reverse transcription PCR; RT-qPCR), and histological analyses were performed on the placentas. To identify local and/or systemic immune changes during the early implantation period, 8 mice of the TAM group and 12 mice of the control group were sacrificed at E4.5. Uterine horns and spleens were collected for flow cytometry and RT-qPCR analyses to study the immune cell populations. To investigate the profile of the cytokines secreted during the early implantation period at the systemic level, supernatants from stimulated spleen cells were analyzed by multiplex immunoassay analysis.

MAIN RESULTS AND THE ROLE OF CHANCE

By ultrasound imaging, we observed a lower number of implantation sites (P < 0.005) and a higher number of resorptions (P < 0.001) in the TAM group, leading to smaller litters (average number of fetuses per litter: 1.00 [0.00; 5.25] in the TAM group versus 12.00 [9.50; 13.75] in the control group (P < 0.001). Histological and morphometric analyses of the placentas at E18.5 showed a higher junctional/labyrinthine area ratio in the TAM group (P = 0.005). The expression levels of genes that play a role in vascularization and placental growth (Vegf (P < 0.001), Plgf (P < 0.005), Pecam (P < 0.0001), and Igf2 (P = 0.002)) were reduced in the TAM group. In the TAM group, the percentages of macrophages, natural killer (NK) cells, and dendritic cells (DC) were significantly decreased in the uterus around the implantation period. However, the number of M1 macrophages was increased. Both macrophages and DC had an increased activation profile (higher expression of MCHII, P = 0.012; CD80, P = 0.015; CCR7, P = 0.043 for macrophages, and higher expression of CD206, P = 0.018; CXCR4, P = 0.010; CCR7, P = 0.006, MCHII, P = 0.010; and CD80, P = 0.012 for DC). In spleen, an increase in the activation of macrophages (CCR7, P = 0.002; MCHII, P = 0.001; and CD80, P = 0.034) and DC was observed in the TAM group (CCR7, P = 0.001; MCHII, P = 0.001; Ly6C, P = 0.015). In the uteri and the spleen, we observed increased percentages of CD4+ T lymphocytes (P = 0.0237 and P = 0.0136, respectively) in the TAM group and, in the uteri, an increased number of regulatory T cells (P = 0.036) compared with the controls.

LARGE SCALE DATA

Not applicable.

LIMITATIONS, REASONS FOR CAUTION

This study is limited by the use of an animal model and the lack of intervention.

WIDER IMPLICATIONS OF THE FINDINGS

These data support involvement of innate and adaptive immune cells in the implantation failure and the increased rate of resorption observed in the mouse model of adenomyosis. This substantiates the need for additional research in this domain, with the goal of addressing fertility challenges in women affected by this condition.

STUDY FUNDING/COMPETING INTEREST(S)

None.

The role of the junctional zone in the management of adenomyosis with infertility

The junctional zone (JZ) is an important structure in the myometrium that maintains uterine fertility. Changes in the junctional zone are closely related to infertility and adenomyosis (ADS). As an increasing number of young women are affected by ADS, the disease is no longer considered typical of women over 40. With these changes, an increasing number of patients refuse hysterectomy and desire fertility preservation treatment. At the same time, ADS is a crucial factor causing female infertility. Therefore, the treatment of ADS-related infertility and preservation of reproductive function is one of the other major challenges facing clinicians. For these young patients, preserving fertility and even promoting reproduction has become a new challenge. Therefore, we searched and summarized these studies on PubMed and Google Scholar using keywords such as "adenomyosis", "junctional zone", and "infertility" to explore infertility causes, diagnosis, and treatment of ADS patients who wish to preserve their uterus or fertility and become pregnant, focusing on the junctional zone, to obtain a full appreciation of the new perspective on this disease.

Cyclic processes in the uterine tubes, endometrium, myometrium, and cervix: pathways and perturbations

This review leads the 2023 Call for Papers in MHR: 'Cyclical function of the female reproductive tract' and will outline the complex and fascinating changes that take place in the reproductive tract during the menstrual cycle. We will also explore associated reproductive tract abnormalities that impact or are impacted by the menstrual cycle. Between menarche and menopause, women and people who menstruate living in high-income countries can expect to experience ∼450 menstrual cycles. The primary function of the menstrual cycle is to prepare the reproductive system for pregnancy in the event of fertilization. In the absence of pregnancy, ovarian hormone levels fall, triggering the end of the menstrual cycle and onset of menstruation. We have chosen to exclude the ovaries and focus on the other structures that make up the reproductive tract: uterine tubes, endometrium, myometrium, and cervix, which also functionally change in response to fluctuations in ovarian hormone production across the menstrual cycle. This inaugural paper for the 2023 MHR special collection will discuss our current understanding of the normal physiological processes involved in uterine cyclicity (limited specifically to the uterine tubes, endometrium, myometrium, and cervix) in humans, and other mammals where relevant. We will emphasize where knowledge gaps exist and highlight the impact that reproductive tract and uterine cycle perturbations have on health and fertility.