hCG Improves Luteal Function and Promotes Progesterone Output through the Activation of JNK Pathway in the Luteal Granulosa Cells of the Stimulated IVF Cycles†

Research Progress on the Impact of Human Chorionic Gonadotropin on Reproductive Performance in Sows

Human chorionic gonadotropin is a glycoprotein hormone produced by human or humanoid syncytiotrophoblasts that differentiate during pregnancy. Due to its superior stability and long-lasting effects compared to luteinizing hormone, it is often used to replace luteinizing hormone to regulate reproductive performance in sows. Human chorionic gonadotropin promotes oocyte maturation, follicle development, and luteinization, thereby increasing conception rates and supporting early embryonic development. In sow reproductive management, the application of human chorionic gonadotropin not only enhances ovulation synchrony but also improves the success rate of embryo implantation by regulating endometrial receptivity and immune mechanisms, significantly enhancing overall reproductive performance. This article primarily reviews the application of human chorionic gonadotropin in sow follicle development, luteal maintenance, and embryo implantation, providing theoretical support for its use in improving reproductive performance in sows.

Exposure of antral follicles to medroxyprogesterone acetate during stimulation does not cause molecular perturbations in gonadotropin-responsiveness and steroidogenic function of granulosa cells in progestin-primed cycles

STUDY QUESTION

Does medroxyprogesterone acetate (MPA) exposure in progestin-primed ovarian stimulation (PPOS) cycles cause molecular perturbations in the steroidogenic function and gonadotropin responsiveness of the granulosa cells?

SUMMARY ANSWER

PPOS cycles are identical to traditional GnRH antagonist cycles not only for clinical IVF characteristics but also for gonadotropin receptor expression, response to gonadotropins, and steroidogenic function at the molecular level.

WHAT IS KNOWN ALREADY

PPOS is increasingly used as an alternative to GnRH antagonists due to the inhibitory effect of progesterone on LH release by reducing GnRH pulsatility at the hypothalamic level. Although a growing body of evidence from clinical studies did not indicate significant differences between PPOS and antagonist protocols for IVF cycle characteristics and obstetrical outcomes, it is still unknown whether exposure of the antral follicle cohort to progesterone or its synthetic derivatives during ovarian stimulation causes any subtle molecular aberrations in terms of steroidogenesis and gonadotropin responsiveness. To address this issue, detailed comparative molecular analyses were conducted in the luteinized mural granulosa cells (GCs) obtained from normal responding IVF patients undergoing PPOS and antagonist cycles.

STUDY DESIGN, SIZE, DURATION

A clinical translational research study was conducted with IVF patients.

PARTICIPANTS/MATERIALS, SETTING, METHODS

This study included 55 normal responding IVF patients who underwent ovarian stimulation with either PPOS using MPA (5 mg twice daily) or GnRH antagonist cetrorelix acetate. Recombinant forms of FSH and hCG were used for ovarian stimulation and ovulation triggering, respectively. Luteinized mural GCs obtained during the oocyte retrieval procedure were used for the experiments. Cell culture, quantitative real-time PCR, immunoblotting, confocal time-lapse live cell imaging, and hormone assays were used.

MAIN RESULTS AND THE ROLE OF CHANCE

Demographic and IVF cycle characteristics of the patients undergoing ovarian stimulation with PPOS and GnRH antagonist were similar, including ovarian response, mature oocyte yield, and fertilization rates. Molecular analyses revealed that the expression of the enzymes involved in sex-steroid synthesis (StAR, SCC, 3β-HSD, 17β-HSD, aromatase) and the uptake/storage/utilization of cholesterol (LDL receptor, Hormone-sensitive lipase, hydroxy-methyl glutaryl Co-enzyme-A reductase, and Sterol O-acyltransferase1) in the GCs of the PPOS cycles were comparable to those of the antagonist cycles. The expression of the receptors for gonadotropins, estrogen, and progesterone hormones was also similar. Basal and hCG-induced increases in 3β-HSD expression and progesterone production and basal and FSH-induced increases in aromatase expression and E2 output of the GCs from PPOS patients did not exhibit any meaningful differences when compared with GCs from antagonist cycles. Furthermore, basal and hCG-induced up-regulation in the LDL receptor expression and cholesterol uptake did not differ between the groups. Confocal imaging also revealed similar patterns of expression for the steroidogenic enzymes and their co-localization with mitochondria. Lastly, the expression of the other important genes regulating cumulus expansion, ovulation, and luteal function [Relaxin, ADAMTS-1, and epidermal growth factor (EGF)-like growth factor amphiregulin] in the GCs of the PPOS and antagonist cycles were similar.

LARGE SCALE DATA

N/A.

LIMITATIONS, REASONS FOR CAUTION

Caution should be exercised when interpreting our data which was derived from normally responding patients whose ovulation was triggered with hCG. It is unclear whether the molecular parameters assessed vary according to infertility etiologies, magnitude of ovarian response, mode of trigger, and any other underlying ovarian pathologies or systemic diseases. MPA was the progestin used for PPOS and whether these findings can be generalized to other progestins is unknown.

WIDER IMPLICATIONS OF THE FINDINGS

This study provides reassuring molecular evidence that exposure of antral follicle cohorts to MPA during the follicular growth phase does not have any detrimental effects on steroidogenic, ovulatory, and luteal functions when compared with GnRH antagonist cycles.

STUDY FUNDING/COMPETING INTEREST(S)

This study was funded by the School of Medicine, the Graduate School of Health Sciences of Koc University and Koç University Research Center for Translational Medicine (KUTTAM), and equally funded by the Republic of Turkey Ministry of Development Research Infrastructure Support Program. All authors declare no conflict of interest.

TRIAL REGISTRATION NUMBER

N/A.

Progesterone concentrations on blastocyst transfer day in modified natural cycle frozen embryo transfer cycles

RESEARCH QUESTION

Are serum progesterone concentrations on the day of modified natural cycle (mNC) frozen blastocyst transfer (FET) without luteal phase support (LPS) associated with clinical pregnancy rate (CPR)?

DESIGN

Data were collected between January 2019 and October 2022 as a sub-study of an ongoing randomized controlled trial assessing pregnancy outcomes in mNC-FET. The sub-study included all women (n = 209) randomized to mNC-FET without LPS at the time of data extraction. Participants were aged 18-41 years, had regular menstrual cycles and underwent mNC-FET treatment with single-blastocyst transfer. Associations between the serum progesterone concentration on the day of blastocyst transfer and CPR, pregnancy rate and pregnancy loss rate (PLR) were examined between groups with low and higher progesterone concentrations using the 25th and 10th percentiles as cut-offs. Multivariate logistic regression analyses were performed to adjust for potential confounding factors.

RESULTS

Progesterone concentrations on the day of blastocyst transfer in mNC-FET without LPS ranged from 4.9 to 91.8 nmol/l, with the 25th and 10th percentiles at 29.0 nmol/l and 22.5 nmol/l, respectively. Serum progesterone concentrations did not differ between women with or without a clinical pregnancy (mean [SD] 38.5 [14.0] versus 36.8 [12.4] nmol/l; P = 0.350). Furthermore, the CPR, pregancy rate and PLR were similar in women with low or high progesterone concentrations when using the 25th or the 10th progesterone percentile as cut-off. Multivariate regression analyses showed no association between progesterone concentrations and CPR.

CONCLUSIONS

No association was found between progesterone concentration on the day of blastocyst transfer and pregnancy outcome in women undergoing mNC-FET without progesterone LPS.

Patients with gynecological malignancies are similar to other IVF patients without cancer for clinical and molecular reproductive parameters and DNA damage response pattern

This study intended to investigate if gynecological cancers compromise ovarian function and reduce the success of assisted reproduction techniques (ART). No clinical and molecular data together is available on this issue for gynecological or other organ cancers. Steroidogenic pathways and DNA damage response characteristics of the granulosa cells retrieved from the 39 gynecological cancer patients were analyzed together with their clinical ART characteristics in comparison to 31 control ART patients. Patients with gynecological malignancies were similar to the control IVF patients for the number of mature oocytes retrieved, fertilization rates and embryo development competency. Molecular analyses of the granulosa cells retrieved from these cancer patients did not detect any perturbations in gonadotropin receptor expression and response, sex steroid production, cholesterol utilization/storage and, DNA damage response pattern in comparison to control IVF patients without cancer. This study provides the first reassuring clinical and molecular combined data set that the presence of gynecological malignancy does not appear to have any detrimental effect on clinical IVF cycle characteristics and ovarian functioning at molecular level.

Reproductive toxicity of PFOA, PFOS and their substitutes: A review based on epidemiological and toxicological evidence

Per- and polyfluoroalkyl substances (PFAS) have already drawn a lot of attention for their accumulation and reproductive toxicity in organisms. Perfluorooctanoic acid (PFOA) and perfluorooctanoic sulfonate (PFOS), two representative PFAS, are toxic to humans and animals. Due to their widespread use in environmental media with multiple toxicities, PFOA and PFOS have been banned in numerous countries, and many substitutes have been produced to meet market requirements. Unfortunately, most alternatives to PFOA and PFOS have proven to be cumulative and highly toxic. Of the reported multiple organ toxicities, reproductive toxicity deserves special attention. It has been confirmed through epidemiological studies that PFOS and PFOA are not only associated with reduced testosterone levels in humans, but also with an association with damage to the integrity of the blood testicular barrier. In addition, for women, PFOA and PFOS are correlated with abnormal sex hormone levels, and increase the risk of infertility and abnormal menstrual cycle. Nevertheless, there is controversial evidence on the epidemiological relationship that exists between PFOA and PFOS as well as sperm quality and reproductive hormones, while the evidence from animal studies is relatively consistent. Based on the published papers, the potential toxicity mechanisms for PFOA, PFOS and their substitutes were reviewed. For males, PFOA and PFOS may produce reproductive toxicity in the following five ways: (1) Apoptosis and autophagy in spermatogenic cells; (2) Apoptosis and differentiation disorders of Leydig cells; (3) Oxidative stress in sperm and disturbance of Ca2+ channels in sperm membrane; (4) Degradation of delicate intercellular junctions between Sertoli cells; (5) Activation of brain nuclei and shift of hypothalamic metabolome. For females, PFOA and PFOS may produce reproductive toxicity in the following five ways: (1) Damage to oocytes through oxidative stress; (2) Inhibition of corpus luteum function; (3) Inhibition of steroid hormone synthesis; (4) Damage to follicles by affecting gap junction intercellular communication (GJIC); (5) Inhibition of placental function. Besides, PFAS substitutes show similar reproductive toxicity with PFOA and PFOS, and are even more toxic to the placenta. Finally, based on the existing knowledge, future developments and direction of efforts in this field are suggested.

Autophagy regulates sex steroid hormone synthesis through lysosomal degradation of lipid droplets in human ovary and testis

Autophagy is an evolutionarily conserved process that aims to maintain the energy homeostasis of the cell by recycling long-lived proteins and organelles. Previous studies documented the role of autophagy in sex steroid hormone biosynthesis in different animal models and human testis. Here we demonstrate in this study that sex steroid hormones estrogen and progesterone are produced through the same autophagy-mediated mechanism in the human ovary in addition to the human testis. In brief, pharmacological inhibition and genetic interruption of autophagy through silencing of autophagy genes (Beclin1 and ATG5) via siRNA and shRNA technologies significantly reduced basal and gonadotropin-stimulated estradiol (E₂), progesterone (P₄) and testosterone (T) production in the ex vivo explant tissue culture of ovary and testis and primary and immortalized granulosa cells. Consistent with the findings of the previous works, we observed that lipophagy, a special form of autophagy, mediates the association of the lipid droplets (LD)s with lysosome to deliver the lipid cargo within the LDs to lysosomes for degradation in order to release free cholesterol required for steroid synthesis. Gonadotropin hormones are likely to augment the production of sex steroid hormones by upregulating the expression of autophagy genes, accelerating autophagic flux and promoting the association of LDs with autophagosome and lysosome. Moreover, we detected some aberrations at different steps of lipophagy-mediated P₄ production in the luteinized GCs of women with defective ovarian luteal function. The progression of autophagy and the fusion of the LDs with lysosome are markedly defective, along with reduced P₄ production in these patients. Our data, together with the findings of the previous works, may have significant clinical implications by opening a new avenue in understanding and treatment of a wide range of diseases, from reproductive disorders to sex steroid-producing neoplasms, sex steroid-dependent malignancies (breast, endometrium, prostate) and benign disorders (endometriosis).

IVF characteristics and the molecular luteal features of random start IVF cycles are not different from conventional cycles in cancer patients

STUDY QUESTION

Are the IVF parameters and the steroidogenic luteal characteristics of random-start IVF cycles different from conventional cycles in cancer patients?

SUMMARY ANSWER

No; controlled ovarian stimulation cycles randomly started at late follicular phase (LFP) and luteal phase (LP) are totally comparable to those conventional IVF cycles started at early follicular phase (EFP) in terms of the expression of the enzymes involved in cholesterol utilization and steroid hormone biosynthesis pathways, gonadotropin receptor expression and, estradiol (E2) and progesterone (P4) production in addition to the similarities in ovarian response to gonadotropin stimulation, oocyte yield, fertilization rate and embryo development competency in cancer patients.

WHAT IS KNOWN ALREADY

Random start ovarian stimulation protocols are commonly employed for oocyte and embryo freezing for fertility preservation in cancer patients with time constraints who do not have sufficient time to undergo ovarian stimulation initiated conventionally at EFP of the next cycle. No data is available regarding the molecular steroidogenic features of these cycles analyzed together with the clinical IVF characteristics in cancer patients. We aimed to address this question in this study to help understand how similar the random start cycles are to the conventional start ones.

STUDY DESIGN, SIZE, DURATION

A clinical translational research study conducted in 62 cancer patients undergoing IVF for fertility preservation between the years 2017 and 2022.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Sixty-two patients who were diagnosed with different types of cancer and underwent ovarian stimulation for oocyte (n = 41) and embryo (n = 21) cryopreservation using GnRH antagonist protocol and human menopausal gonadotropins before receiving cancer treatment/surgery were enrolled in the study. For patients with breast cancer and endometrial cancer the aromatase inhibitor letrozole was used with gonadotropin stimulation. Ovarian stimulation was initiated conventionally at EFP in 22 patients and served as control while it was started at LFP in 20, and mid-LP in the other 20 patients. The luteinized granulosa cells (GCs) were recovered from follicular aspirates during oocyte retrieval procedure and used for the experiments separately for each individual patient. The expression of the enzymes involved in sex steroid biosynthesis (StAR, 3β-HSD, Aromatase) and cholesterol synthesis (3-hydroxy 3-methylglutaryl Co-A reductase (HMG-Co-A reductase)), utilization (hormone sensitive lipase (HSL)), and storage (Acetyl-Coenzyme A acetyltransferase 1 (ACAT-1)), and gonadotropin receptor expression status were analyzed using immunoblotting and RT-PCR methods. Laser confocal immunofluorescence imaging was applied to analyze and compare the expression patterns of the steroidogenic enzymes and their relation with mitochondria. In vitro E2 and P4 production by the cells were compared among the groups.

MAIN RESULTS AND THE ROLE OF CHANCE

Baseline demographic and IVF characteristics of the patients undergoing the conventional start and random start IVF cycles were similar. Duration of gonadotropin stimulation was significantly longer in LFP and LP start cycles in comparison to the conventional ones. Ovarian response to gonadotropin stimulation, mature and total oocyte yield, fertilization and Day 5 blastulation rates of the embryos were comparable between the conventional versus random start cycles. When the luteal GCs of these random start cycles were analyzed we could not find any gross differences between these cycles in terms of the viability index and gross light microscopic morphologic features. More detailed analysis of the molecular luteal characteristics of the cells using RT-PCR, immunoblotting methods revealed that the expression profiles of the gonadotropin receptors, and the enzymes involved in sex steroid biosynthesis and cholesterol synthesis/utilization, and the steroidogenic activity of the luteal GCs of the random start cycles are almost identical to those of the conventional start cycles. Confocal image analysis demonstrated similar patterns in the signal expression profiles of the steroidogenic enzymes and their co-localization within mitochondria.

LARGE SCALE DATA

N/A.

LIMITATIONS, REASONS FOR CAUTION

Caution should be exercised when interpreting our data and counseling cancer patients seeking fertility preservation because it is still unclear if previous exposure to cancer drugs, different ovarian pathologies or infertility etiologies, previous ovarian surgery and/or any other underlying diseases that are concomitantly present with cancer may cause a difference between conventional and random start stimulation protocols in terms of IVF parameters, luteal function and reproductive outcome. Relatively low number of patients in each stimulation protocol and pooling of luteal GCs for each patient rather than individual analysis of each follicle and oocyte are additional limitations of our study.

WIDER IMPLICATIONS OF THE FINDINGS

Our findings provide reassurance that random start protocol offers cancer patients an equally good prospect of fertility preservation as conventional IVF.

STUDY FUNDING/COMPETING INTEREST(S)

Funded by the School of Medicine, the Graduate School of Health Sciences of Koc University and Koç University Research Center for Translational Medicine (KUTTAM), equally funded by the Republic of Turkey Ministry of Development Research Infrastructure Support Program. All authors declare no conflict of interest.

TRIAL REGISTRATION NUMBER

N/A.

Recent advances in understanding gonadotropin signaling

Gonadotropins are glycoprotein sex hormones regulating development and reproduction and bind to specific G protein–coupled receptors expressed in the gonads. Their effects on multiple signaling cascades and intracellular events have recently been characterized using novel technological and scientific tools. The impact of allosteric modulators on gonadotropin signaling, the role of sugars linked to the hormone backbone, the detection of endosomal compartments supporting signaling modules, and the dissection of different effects mediated by these molecules are areas that have advanced significantly in the last decade. The classic view providing the exclusive activation of the cAMP/protein kinase A (PKA) and the steroidogenic pathway by these hormones has been expanded with the addition of novel signaling cascades as determined by high-resolution imaging techniques. These new findings provided new potential therapeutic applications. Despite these improvements, unanswered issues of gonadotropin physiology, such as the intrinsic pro-apoptotic potential to these hormones, the existence of receptors assembled as heteromers, and their expression in extragonadal tissues, remain to be studied. Elucidating these issues is a challenge for future research.

Terminal differentiation of human granulosa cells as luteinization is reversed by activin-A through silencing of Jnk pathway

Molecular mechanisms underlying luteinization (terminal differentiation of granulosa and theca cells after ovulation) and luteolysis (demise of corpus luteum) are poorly understood in human ovary. Here we report that activin-A, after binding to its cognate receptors induces a functional luteolytic state and reverses luteinization phenotype by downregulating the expression of the steroidogenic enzymes, LH receptor and VEGF and reducing estradiol (E2) progesterone (P4) production and upregulating FSH receptor and cyclin D1 expression in human primary luteinized granulosa cells. Further, this action of activin-A involves downregulation of JNK signaling pathway and is opposite to that of human chorionic gonadotropin (hCG), which acts as a luteotropic hormone and improves luteal function through the activation of JNK pathway in the same cell type. Reversal of luteinization phenotype in luteal granulosa cells by activin-A potentially makes this hormone an attractive candidate for use under certain clinical situations, where induction of luteolysis and rapid reduction of endogenous sex steroid levels are beneficial such as ovarian hyperstimulation syndrome (OHSS), in which the ovaries hyper-respond to gonadotropin stimulation by producing too many growing follicles along with development of ascites, pleural effusion, and hemo-concentrations as a result of increased vascular permeability and leakage of intravascular volume into third spaces. Our work unveils a previously undefined role for activin-A and JNK signaling pathway in human corpus luteum biology, that might have a direct clinical impact in assisted reproductive technologies.

Ephrin and Eph receptor signaling in female reproductive physiology and pathology†

Ephrins are ligands of Eph receptors (Ephs); both of which are sorted into two classes, A and B. There are five types of ephrin-As (ephrin-A1-5) and three types of ephrin-Bs (ephrin-B1-3). Also, there are 10 types of EphAs (EphA1-10) and six types of EphBs (EphB1-6). Binding of ephrins to the Eph receptors activates signaling cascades that regulate several biological processes such as cellular proliferation, differentiation, migration, angiogenesis, and vascular remodeling. Clarification of their roles in the female reproductive system is crucial to understanding the physiology and pathology of this system. Such knowledge will also create awareness regarding the importance of these molecules in diagnostic, prognostic, and therapeutic medicine. Hence, we have discussed the involvement of these molecules in the physiological and pathological events that occur within the female reproductive system. The evidence so far suggests that the ephrins and the Eph receptors modulate folliculogenesis, ovulation, embryo transport, implantation, and placentation. Abnormal expression of some of these molecules is associated with polycystic ovarian syndrome, ovarian cancer, tubal pregnancy, endometrial cancer, uterine leiomyoma (fibroids), cervical cancer, and preeclampsia, suggesting the need to utilize these molecules in the clinical setting. To enhance a quick development of this gradually emerging field in female reproductive medicine, we have highlighted some "gaps in knowledge" that need prospective investigation.