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

Adenomyosis is a debilitating gynecological disease of the uterus with no medicinal cure. The tissue injury and repair hypothesis for adenomyosis suggests that uterine hyperperistalsis or dysperistalsis plays a pivotal role in establishing adenomyotic lesions. However, specific impairments in uterine peristalsis and the underlying cellular signals for these changes in adenomyosis remain elusive. Here, we report a precision-cut uterine slice preparation that preserves in vivo uterine architecture and generates peristalsis similar to that seen in the whole uterus. We found that uterine peristalsis in neonatal mice at day 14 and adult mice at day 55 presents as bursts with multiple peaks induced by intracellular Ca2+ oscillations. Using a mouse model of adenomyosis induced by tamoxifen, a selective estrogen receptor modulator, we discovered that uterine peristalsis and Ca2+ oscillations from adenomyotic uteri on days 14 and 55 become spikes (single peaks) with smaller amplitudes. The peak frequency of Ca2+ oscillations or peristalsis does not show a difference between control and adenomyotic mice. However, both the estimated force generated by uterine peristalsis and the total Ca2+ raised by Ca2+ oscillations are smaller in uteri from adenomyotic mice. Uteri from adenomyotic mice on day 14, but not on day 55, exhibit hyperresponsiveness to oxytocin. Embryo implantations are decreased in adenomyotic adult mice. Our results reveal a mode switch from bursts to spikes (rather than an increased peak frequency) of uterine Ca2+ oscillations and peristalsis and concurrent hyperresponsiveness to oxytocin in the neonatal stage are two characteristics of adenomyosis. These characteristics may contribute to embryo implantation impairments and decreased fertility in adenomyosis.

Ascension of Chlamydia is moderated by uterine peristalsis and the neutrophil response to infection

Chlamydia trachomatis is a common sexually transmitted infection that is associated with a range of serious reproductive tract sequelae including in women Pelvic Inflammatory Disease (PID), tubal factor infertility, and ectopic pregnancy. Ascension of the pathogen beyond the cervix and into the upper reproductive tract is thought to be necessary for these pathologies. However, Chlamydia trachomatis does not encode a mechanism for movement on its genome, and so the processes that facilitate ascension have not been elucidated. Here, we evaluate the factors that may influence chlamydial ascension in women. We constructed a mathematical model based on a set of stochastic dynamics to elucidate the moderating factors that might influence ascension of infections in the first month of an infection. In the simulations conducted from the stochastic model, 36% of infections ascended, but only 9% had more than 1000 bacteria ascend. The results of the simulations indicated that infectious load and the peristaltic contractions moderate ascension and are inter-related in impact. Smaller initial loads were much more likely to ascend. Ascension was found to be dependent on the neutrophil response. Overall, our results indicate that infectious load, menstrual cycle timing, and the neutrophil response are critical factors in chlamydial ascension in women.

P–613 Adjuvant letrozole in ovarian stimulation for in vitro fertilization does not reduce uterine peristalsis frequency prior to fresh embryo transfer

Study question Does adjuvant letrozole in ovarian stimulation (OS) for in vitro fertilization (IVF) decrease the uterine peristalsis frequency (UPF) prior to fresh embryo transfer (ET)? Summary answer Adjuvant letrozole in (OS) for IVF does not reduce the UPF significantly prior to fresh ET. What is known already Throughout the cycle UPF aids spermatozoa transport to the fallopian tube and may affect implantation. At fresh, ET UPF is negatively correlated with implantation- and clinical pregnancy rates and is believed to be modulated by estradiol and progesterone. High levels of estradiol, from multiple follicular development, in OS have been reported to increase UPF, whereas progesterone is considered to be utero-relaxant. The influence of androgens is unclear. Co-treatment with letrozole during gonadotropin OS limits the estradiol rise the supra-physiological estradiol and may therefore reduce UPF prior to fresh ET. Study design, size, duration: This single centre study was nested within a multicentre double blinded RCT investigating the impact of letrozole co-treatment during gonadotropin OS for IVF on late follicular and luteal estradiol, progesterone and testosterone levels. Between 2016 and 2017, 39 women expected normal responders were randomised to co-treatment with letrozole or placebo. Of these, 33 women completed this element of the study. The study was carried out according to the Helsinki Declaration and the ICH-Good-Clinical-Practice. Participants/materials, setting, methods Eligible women were randomised 1:1 to adjuvant treatment with letrozole 5 mg/day or placebo in an antagonist protocol using a fixed dose of recFSH 150 IU/day. Final maturation was triggered with rhCG 6,500 IU and luteal support with vaginal progesterone was administered from the day following oocyte aspiration. Less than one hour prior to fresh ET, six minute duration transvaginal ultrasound recordings of the uterus in sagittal section were performed and blood samples were drawn. Main results and the role of chance A total of 33 women completed the study (letrozole n = 17; placebo n = 16). Age, BMI, and ovarian reserve markers were similar between the groups. On day of ET, serum estradiol levels were significantly suppressed in the letrozole group to mean 867 ± 827 pmol/L compared to 3,110 ± 1,528 pmol/L in the placebo group (P < 0.0001). Mean UPF prior to fresh ET did not differ between the intervention and control group (3.3 ± 0.36 versus 3.5 ± 0.51 per minute respectively, P = 0.108). UPF was assessed and agreed by two observers who were blind to adjuvant treatment. Two patients were excluded due to poor quality of the ultra sound recording. Supra-physiological serum estradiol in the placebo group was negatively correlated with UPF (P = 0.014; R = –0.62), but the more physiological serum estradiol levels in the letrozole group showed no correlation with UPF (P = 0.567; R = 0.15). Serum progesterone levels were similar in both groups and did not show any significant correlation with UPF. Testosterone levels were significantly higher in the letrozole group (P = 0.005) and showed a non-significant trend negatively correlated with UPF in the placebo group (P-value=0.07, R= –0.48). Limitations, reasons for caution The limited sample size risks masking minor effects. Wider implications of the findings: The supra-physiological levels of estradiol were significantly supressed in the intervention group, but UPF prior to fresh ET was similar in both groups. UPF is not strongly correlated to luteal phase sex steroid levels. Any beneficial effect of adjuvant letrozole during OS is not through an impact of UPF. Trial registration number NCT02939898