Ovarian stimulation affects the population of mouse uterine NK cells at early pregnancy

The effects of progesterone on immune cellular function at the maternal-fetal interface and in maternal circulation

Progesterone is a sex steroid hormone that plays a critical role in the establishment and maintenance of pregnancy. This hormone drives numerous maternal physiological adaptations to ensure the continuation of pregnancy and to facilitate fetal growth, including broad and potent modulation of the maternal immune system to promote maternal-fetal tolerance. In this brief review, we provide an overview of the immunomodulatory functions of progesterone in the decidua, placenta, myometrium, and maternal circulation during pregnancy. Specifically, we summarize current evidence of the regulated functions of innate and adaptive immune cells induced by progesterone and its downstream effector molecules in these compartments, including observations in human pregnancy and in animal models. Our review highlights the gaps in knowledge of interactions between progesterone and maternal cellular immunity that may direct future research.

Superovulation with human chorionic gonadotropin (hCG) trigger and gonadotropin releasing hormone agonist (GnRHa) trigger differentially alter essential angiogenic factors in the endometrium in a mouse ART model†

Gonadotropin-releasing hormone agonists (GnRHa) are used as an alternative to human chorionic gonadotropin (hCG) to trigger ovulation and decrease the risk of ovarian hyperstimulation syndrome. GnRHa is less potent at inducing ovarian vascular endothelial growth factor (VEGF), but may also affect endometrial angiogenesis and early placental development. In this study, we explore the effect of superovulation on endometrial angiogenesis during critical periods of gestation in a mouse model. We assigned female mice to three groups: natural mating or mating following injection with equine chorionic gonadotropin and trigger with GnRHa or hCG trigger. Females were killed prior to implantation (E3.5), post-implantation (E7.5), and at midgestation (E10.5), and maternal serum, uterus, and ovaries were collected. During peri-implantation, endometrial Vegfr1 and Vegfr2 mRNA were significantly increased in the GnRHa trigger group (P < 0.02) relative to the hCG group. Vegfr1 is highly expressed in the endometrial lining and secretory glands immediately prior to implantation. At E7.5, the ectoplacental cone expression of Vegfa and its receptor, Vegfr2, was significantly higher in the hCG trigger group compared to the GnRHa group (P < 0.05). Soluble VEGFR1 and free VEGFA were much higher in the serum of mice exposed to the hCG trigger compared to GnRHa group. At midgestation, there was significantly more local Vegfa expression in the placenta of mice triggered with hCG. GnRHa and hCG triggers differentially disrupt the endometrial expression of key angiogenic factors during critical periods of mouse gestation. These results may have significant implications for placental development and neonatal outcomes following human in vitro fertilization.

Superovulation with gonadotropin-releasing hormone agonist or chorionic gonadotropin for ovulation trigger differentially affects leukocyte populations in the peri-implantation mouse uterus

OBJECTIVE

To investigate the effect of superovulation with human chorionic gonadotropin (hCG) or gonadotropin-releasing hormone agonist (GnRHa) trigger on leukocyte density and expression of leukocyte-specific genes in the peri-implantation period in the mouse uterus.

DESIGN

Laboratory research.

SETTING

University laboratory facility.

INTERVENTIONS

Female mice were mated to fertile male mice in one of three protocols: (1) natural mating or mating following injection with pregnant mare serum gonadotropin followed by trigger with (2) GnRHa or (3) hCG. Female mice were killed prior to implantation, 3 days after ovulation (E3.5), and the ovaries and uterine tissue were collected. Total RNA was isolated and assayed using quantitative reverse transcription polymerase chain reaction, and the uterine tissue was stained for histologic analysis of immune cell markers.

MAIN OUTCOME MEASURES

Endometrial leukocyte (CD45) and vessel density (CD31) by immunohistochemical staining; expression of leukocyte markers CD11b, CD335, and CD22, by quantitative reverse transcription polymerase chain reaction in the whole uterine tissue.

RESULTS

Superovulation decreased (compared with controls) the endometrial leukocyte density, based on the number of cells staining for CD45, and endometrial vessel density, based on the number of cells staining for CD31. Leukocyte density was additionally decreased in the GnRHa trigger group compared with that in the hCG trigger group. Superovulation with hCG and GnRHa triggers decreased the uterine expression of the B-cell marker CD22 compared with controls. The expression of the natural killer cell marker CD11b was decreased by the hCG trigger but not by the GnRHa. Abundance of mRNA encoding the CD335 natural killer cell marker was not affected by superovulation or trigger agent.

CONCLUSIONS

In mice, superovulation with the GnRHa trigger compared with that with the hCG trigger differentially alters key immunologic factors in the uterine peri-implantation. These altered immunologic factors have roles in angiogenesis that may assist in elucidating the effects of assisted reproductive technologies on implantation efficiency and fetal growth and development.

New endometrial immune cell-based score (EI-score) for the prediction of implantation success for patients undergoing IVF/ICSI

PROBLEM

Limited evidence revealed whether endometrial immunological factors contribute to implantation success in the first-attempted in vitro fertilization/intracytoplasmic sperm injection (IVF/ICSI) patients.

METHOD

The retrospective study was conducted among 139 eligible couples in the derivation cohort and 29 couples in the validation cohort. The expression of endometrial immune cell markers, including CD56 for natural killer cell, CD68 for pan-macrophage, CD163 for M2 macrophage, FOXP3 for regulatory T cell, CD1a for immature dendritic cell, CD83 for mature dendritic cell, CD8 for cytotoxic T cell and CD57 for mature NK and T cells were examined.

RESULTS

The profiles of endometrial immune cells showed significant difference between the pregnant and implantation failure group in the derivation cohort. Multivariate logistic regression analysis showed that the percentage of CD68⁺ pan-macrophage and CD163⁺ M2-macrophage, as well as the transfer strategy are associated with implantation outcomes (P < 0.001, P = 0.029, P = 0.004, respectively). The EI-score was constructed by a nomogram and validated by a clinical decision curve based on CD68⁺ pan-macrophage, CD163⁺ M2-macrophage, and the transfer strategy. The performance of the EI-score in the deviation cohort showed a c-index of 0.82 (95% CI 0.74-0.89), and the accuracy rate reached 79.3% in the validation cohort.

CONCLUSIONS

The endometrial immunological profiles in the mid-secretory phase is associated with implantation outcome in the first IVF/ICSI patients. EI-Score could help clinicians calculate the probability of implantation success via nomogram. Optimal decision point is determined by decision curve analysis and clinical impact curve, to aid in clinical decisions.

Embryo responses to stress induced by assisted reproductive technologies

Assisted reproductive technology (ART) has led to the birth of millions of babies. In cattle, thousands of embryos are produced annually. However, since the introduction and widespread use of ART, negative effects on embryos and offspring are starting to emerge. Knowledge so far, mostly provided by animal models, indicates that suboptimal conditions during ART can affect embryo viability and quality, and may induce embryonic stress responses. These stress responses take the form of severe gene expression alterations or modifications in critical epigenetic marks established during early developmental stages that can persist after birth. Unfortunately, while developmental plasticity allows the embryo to survive these stressful conditions, such insult may lead to adult health problems and to long-term effects on offspring that could be transmitted to subsequent generations. In this review, we describe how in mice, livestock, and humans, besides affecting the development of the embryo itself, ART stressors may also have significant repercussions on offspring health and physiology. Finally, we argue the case that better control of stressors during ART will help improve embryo quality and offspring health.

Deferred Frozen Embryo Transfer: What Benefits can be Expected from this Strategy in Patients with and without Endometriosis?

Progress with cryopreservation techniques have enabled development of the deferred frozen-thawed embryo transfer (DET) strategy as an alternative to relying on fresh embryo transfers.

With DET, the entire embryo cohort is cryopreserved, and embryo transfer is then performed in a subsequent cycle that takes place separately from the controlled ovarian stimulation (COS).

Initially developed to limit the risk of ovarian hyperstimulation syndrome that occurs with high responders, this strategy has been applied extensively with other populations in an effort to improve implantation rates. The assumption is that COS, which is essential for in vitro fertilization/intra cytoplasmic sperm injection (IVF/ICSI) procedures to obtain a multi-follicular development, could have a detrimental impact on the endometrium as a result of greatly elevated levels of steroids. It is currently not clear whether the DET strategy can be generally applied to all women requiring an IVF/ICSI procedure.

The objectives of this literature review regarding DET, were hence: (i) to present the scientific background that contributed to extensive adoption of this technique, (ii) to detail the pregnancy outcomes and potential obstetric and neonatal consequences, (iii) to report on its ability to prevent risks induced by COS, and (iv) to propose indications for the DET strategy in clinical practice.

Why we should transfer frozen instead of fresh embryos: the translational rationale

Epidemiologic studies have shown an increased rate of adverse perinatal outcomes, including small for gestational age (SGA) births, in fresh in vitro fertilization (IVF) cycles compared with frozen embryo transfer cycles. This increase is not seen in the donor oocyte population, suggesting that it is the peri-implantation environment created after superovulation that is responsible for these changes. During a fresh IVF cycle, multiple corpora lutea secrete high levels of hormones and other factors that can affect the endometrium and the implanting embryo. In this review, we discuss both animal and human data demonstrating that superovulation has significant effects on the endometrium and embryo. Additionally, potential mechanisms for the adverse effects of gonadotropin stimulation on implantation and placental development are proposed. We think that these data, along with the growing body of epidemiologic evidence, support the proposal that frozen embryo transfer should be considered preferentially, particularly in high responders, as a means to potentially decrease at least some of the adverse perinatal outcomes associated with IVF.