High Variability of Molecular Isoforms of AMH in Follicular Fluid and Granulosa Cells From Human Small Antral Follicles

Dissecting the shared genetic architecture between anti-Müllerian hormone and age at menopause based on genome-wide association study

BACKGROUND

While the phenotypic association between anti-Müllerian hormoneand age at menopause has been widely studied, the role of anti-Müllerian hormone in predicting the age at menopause is currently controversial, and the genetic architecture or causal relationships underlying these 2 traits is not well understood.

AIM

We aimed to explore the shared genetic architecture between anti-Müllerian hormone and age at menopause, to identify shared pleiotropic loci and genes, and to investigate causal association and potential causal mediators.

STUDY DESIGN

Using summary statistics from publicly available genome-wide association studies on anti-Müllerian hormone (N=7049) and age at menopause (N=201,323) in Europeans, we investigated the global genetic architecture between anti-Müllerian hormone and age at menopause through linkage disequilibrium score regression. We employed pleiotropic analysis under composite null hypothesis, Functional Mapping and Annotation of Genetic Associations, multimarker analysis of GenoMic annotation, and colocalization analysis to identify loci and genes with pleiotropic effects. Tissue enrichment analysis based on Genotype-Tissue Expression data was conducted using the Linkage Disequilibrium Score for the specific expression of genes analysis. Functional genes that were shared were additionally identified through summary data-based Mendelian randomization. The relationship between anti-Müllerian hormone and age at menopause was examined through 2-sample Mendelian randomization, and potential mediators were further explored using colocalization and metabolite-mediated analysis.

RESULTS

A positive genetic association (correlation coefficient=0.88, P=1.33×10-5) was observed between anti-Müllerian hormone and age at menopause. By using pleiotropic analysis under composite null hypothesis and Functional Mapping and Annotation of Genetic Associations, 42 significant pleiotropic loci were identified that were associated with anti-Müllerian hormone and age at menopause, and 10 of these (rs10734411, rs61913600, rs2277339, rs75770066, rs28416520, rs9796, rs11668344, rs403727, rs6011452, and rs62237617) had colocalized loci. Additionally, 245 significant pleiotropic genes were identified by multimarker analysis of GenoMic annotation. Genetic associations between anti-Müllerian hormone and age at menopause were markedly concentrated in various tissues including whole blood, brain, heart, liver, muscle, pancreas, and kidneys. Further, summary data-based Mendelian randomization analysis revealed 9 genes that may have a causative effect on both anti-Müllerian hormone and age at menopause. A potential causal effect of age at menopause on anti-Müllerian hormone was suggested by 2-sample Mendelian randomization analysis, with very-low-density lipoprotein identified as a potential mediator.

CONCLUSION

Our study revealed a shared genetic architecture between anti-Müllerian hormone and age at menopause, providing a basis for experimental investigations and individual therapies to enhance reproductive outcomes. Furthermore, our findings emphasized that relying solely on anti-Müllerian hormone is not sufficient for accurately predicting the age at menopause, and a combination of other factors needs to be considered. Exploring new therapeutics aimed at delaying at the onset of menopause holds promise, particularly when targeting shared genes based on their shared genetic architecture.

Midkine characterization in human ovaries: potential new variants in follicles

OBJECTIVE

To characterize the growth factor midkine (MDK) in the human ovary to determine whether MDK is produced locally within the ovary, examine whether different ovarian cell types are more likely to produce MDK, and determine whether there are any stage-specific variations during follicle growth. Previous studies have revealed that MDK potentially affects human follicle growth and oocyte maturation. Proteomic analyses in follicular fluid (FF) have identified MDK to functionally cluster together and follow a similar expression profile to that of well-known proteins involved in ovarian follicle development. Midkine has not yet been characterized in the human ovary.

DESIGN

Descriptive study.

SETTING

University Hospital.

PATIENTS

The study included samples from 121 patients: 71 patients (aged 17-37 years) who underwent ovarian tissue cryopreservation provided granulosa cells (GC), cumulus cells, ovarian cortex, medulla tissue, and FF from small antral follicles (SAF); and 50 patients (aged 20-35 years) receiving in vitro fertilization treatment provided FF from preovulatory follicles before and after induction of final follicle maturation.

INTERVENTIONS

None.

MAIN OUTCOME MEASURES

MDK relative gene expression was quantified using a real-time quantitative polymerase chain reaction in cumulus cells, GC, and medulla tissue. Additionally, immunostaining and western blotting assays were used to detect MDK protein in the ovarian cortex, which contains preantral follicles, SAF, and medulla tissue. Furthermore, enzyme-linked immunosorbent assay analyses were performed to measure the concentration of MDK in FF aspirated from SAF and preovulatory follicles both before and 36 hours after inducing the final maturation of follicles.

RESULTS

Immunostaining and reverse transcription-quantitative polymerase chain reaction revealed a more prominent expression of MDK in GC compared with other ovarian cell types. Intrafollicular MDK concentration was significantly higher in SAF compared with preovulatory follicles. In addition, different molecular weight species of MDK were detected using western blotting in various ovarian sample types: GC and FF samples presented primarily one band of approximately 15 kDa and an additional band of approximately 13 kDa, although other bands with higher molecular weight (between 30 and 38 kDa) were detected in medulla tissue.

CONCLUSIONS

This is the first time that MDK has been immunolocalized in human ovarian cells at the protein level and that potentially different MDK variants have been detected in human FF, GC, and ovarian medulla tissue. Future studies are needed to sequence and identify the different potential MDK variants found to determine their functional importance for ovary and oocyte competence.

Expression of genes and enzymes involved in ovarian steroidogenesis in relation to human follicular development

Introduction

Granulosa cells (GCs) and theca cells (TCs) play a pivotal role in human ovarian steroidogenesis, facilitating the conversion of cholesterol into sex steroids that regulate normal reproductive function. This study aims to explore the expression patterns of key enzymes that govern human ovarian steroidogenesis throughout follicle development, employing both genomic and immunological methodologies.

Methods

Follicles and GCs obtained from women undergoing ovarian tissue cryopreservation (OTC) and in vitro fertilisation treatment were utilized. Gene expression data were obtained from a Chinese study using RNA sequencing and from microarray data generated in our laboratory to comprehensively analyse gene expression profiles across distinct stages of follicular development. To corroborate the localisation of key enzymes within GCs and TCs, immunohistochemistry analyses utilizing colourimetric and fluorescent techniques were conducted.

Results

Steroidogenesis-related enzymes displayed low gene expression levels during early follicle development. However, a notable upregulation of HSD3B2 was observed in GCs as follicles progressed to the antral/preovulatory stage, confirmed consistently using both microarray and RNA sequencing methodologies. Furthermore, immunohistochemical analyses effectively demonstrated that HSD3B2 were not only expressed in GCs, but co-localised with CYP17A1 within a specific subset of TCs surrounding human small antral follicles. Contributing to an enhanced progesterone production during the second half of the follicular phase was a significant upregulation of CYB5A in both microarray and RNA-seq datasets as follicles transition from the antral stage to the pre-ovulatory stage. Moreover, an augmented expression of DHCR24 and LDLR in both types of data, along with HMGCR expression expression in the microarray data, indicates increased substrate availability for ovarian steroidogenesis.

Discussion

This study confirms and extends that GCs gradually augment expression of HSD3B2 thereby enhancing their capacity for progesterone synthesis as follicles reach the size of selection at around 10 mm in diameter. This is supported by the expression CYB5A and possibly augmented availability of steroid precursors. A subset of TCs exhibit concurrent expression of CYP17A1 and HSD3B2, collectively contributing to the synthesis of 17-hydroxyprogesterone. These data significantly enhance our understanding of the dynamic regulation of progesterone throughout the process of follicular development.

Anti-Müllerian Hormone levels after metformin treatment in polycystic ovary syndrome: A systematic review and meta-analysis

This systematic review and meta-analysis aim to evaluate whether treatment with metformin would reduce Anti-Müllerian Hormone levels in patients with polycystic ovary syndrome. A search was performed in Medline, Embase, Web of Science, and Cochrane Library databases and grey literature (Google Scholar). The following keywords were used in the search strategy: "Polycystic Ovary Syndrome", "Anti-Mullerian Hormone", "Metformin". The search was limited to human studies, with no language restriction. 328 studies were found, 45 studies were selected for full-text reading and 16 of those studies, six randomized controlled trial and 10 non-randomized studies were included. The synthesis of randomized controlled trials, metformin showed a reduction in serum levels of Anti-Müllerian Hormone compared to control groups (SMD - 0.53, 95 %CI - 0.84 to - 0.22, p < 0.001, I2 = 0 %, four studies, 171 participants, high quality of evidence). Six non-randomized studies evaluated data before and after the metformin intervention. The synthesis showed that using metformin reduced serum Anti-Müllerian Hormone values (SMD - 0.79, 95 %CI - 1.03 to - 0.56, p < 0.001, I2 = 0 %, six studies, 299 participants, low quality of evidence). Metformin administration in women with polycystic ovary syndrome is associated significantly with reduced Anti-Müllerian Hormone serum levels.

Concentrations of oocyte secreted GDF9 and BMP15 decrease with MII transition during human IVM

BACKGROUND

The suggested effects of the oocyte secreted GDF9 and BMP15 growth factors on oocyte maturation are currently based on recombinant proteins, and little is known about native GDF9 and BMP15 in humans.

METHODS

Human immature cumulus-oocyte complexes (COCs) obtained in connection with ovarian tissue cryopreservation (OTC) underwent in vitro maturation (IVM). Oocyte-produced GDF9 and BMP15 were detected in COCs using immunofluorescence, and in fresh GV oocytes and in GV and MII oocytes after IVM by western blot. Concentrations of GDF9, BMP15 homodimers, and GDF9/BMP15 heterodimer in spent media after IVM were measured by ELISA. The relative expression of seven genes from the GDF9 and BMP15 signaling pathways (BMPR2, ALK5, ALK6, SMAD1, SMAD2, SMAD3, and SMAD5) was evaluated in fresh cumulus cells (before IVM) and in cumulus cells from GV and MII oocytes after IVM by RT-qPCR.

RESULTS

We detected native pro-mature GDF9 and BMP15 in human oocytes with molecular weights (Mw) of 47 kDa and 43 kDa, respectively. Concentrations of GDF9 and BMP15 in spent media after IVM were detected in 99% and 64% of the samples, respectively. The GDF9/BMP15 heterodimer was detected in 76% of the samples. Overall, the concentration of GDF9 was approximately 10-times higher than BMP15. The concentrations of both GDF9 and BMP15 were significantly lower in spent medium from MII oocytes than in media from oocytes that remained at the GV stage. Concentrations of the GDF9/BMP15 heterodimer did not differ between GV and MII oocytes. Furthermore, BMPR2, SMAD3, and SMAD5 were significantly upregulated in cumulus cells from MII oocytes, indicating that both GDF9 and BMP15 signaling were active during oocyte meiotic resumption in vitro.

CONCLUSION

These data suggest that the driving mechanisms for oocyte nuclear maturation may involve both GDF9 and BMP15 homodimers, while the role of the GDF9/BMP15 heterodimer is questionable.

Potential Pitfalls of Reproductive Direct-to-Consumer Testing

The availability of direct-to-consumer (DTC) testing has dramatically increased over the past 2 decades, particularly those targeted at reproduction and fertility. Several ethical concerns exist with regard to DTC tests, including the lack of governmental regulation and consumer protection, standardized laboratory methodology, and clinical validity and actionability. Physicians must familiarize themselves with the pitfalls of DTC tests to best aid patients in interpreting DTC test results and guide them toward evidence-based treatment plans.

The role of follicular anti-Mullerian hormone in women undergoing IVF/ICSI with regard to size, oocyte presence, sociodemographic parameters, treatment variables, and other hormones and vitamins

AIMS

The aim of this study was to evaluate the relationship between follicular anti-Mullerian hormone (fAMH) regarding follicle size, the presence of an oocyte, sociodemographic parameters, and other hormones and vitamins in follicular fluid.

MATERIALS AND METHODS

This prospective exploratory cohort study included 376 follicles from 61 women undergoing IVF/ICSI cycles. The size of each follicle was measured individually, and they were divided into a large and a small group according to their size. The presence of oocytes was detected on the day of oocyte retrieval. Sociodemographic factors were documented during the course of preliminary testing. Then, other parameters of patients' serum and follicular fluid were measured.

RESULTS

Small follicles contained a significantly higher concentration of fAMH than large ones did. We showed that the presence of an oocyte in a follicle is associated with a significantly higher fAMH level than in those without one (p < .001). There exists a significant but weak correlation between fAMH and the sociodemographic parameter of patients' age (r = -0.11, p < .001). We did not find a correlation with the patients' BMI (r = 0.03, p < .006). We also investigated the connections between fAMH and other parameters, such as vitamin D (r = -0.13, p < .001), LH (r = 0.35, p < .001)), and progesterone (r = -0.21, p < .001) in follicular fluid.

CONCLUSIONS

This knowledge can be useful for the future development of reproductive medicine. Our results can provide an important building block for this matter.

Challenges in Measuring AMH in the Clinical Setting

Serum anti-Mullerian hormone (AMH) is a widely used marker of functional ovarian reserve in the assessment and treatment of infertility. It is used to determine dosing of gonadotropins used for superovulation prior to in vitro fertilization, as well as to determine the degree of damage to ovarian reserve by cytotoxic treatments such as chemotherapy. AMH is also now used to predict proximity to menopause and potentially provides a sensitive and specific test for polycystic ovarian syndrome. Twenty one different AMH immunoassay platforms/methods are now commercially available. Of those compared, the random-access platforms are the most reliable. However, to date there has not been an agreed common international AMH reference preparation to standardize calibration between the various immunoassays. Recently, a purified human AMH preparation (code 16/190) has been investigated by the World Health Organization as a potential international reference preparation. However, this was only partially successful as commutability between it and serum samples was observed only in some but not all immunoassay methods. Development of a second generation reference preparation with wider commutability is proposed.