Oocyte quality is impaired in a hyperandrogenic PCOS mouse model by increased Foxo1 expression

In vitro maturation in subfertile women with polycystic ovarian syndrome undergoing assisted reproduction

BACKGROUND

Polycystic ovarian syndrome (PCOS) occurs in 8% to 13% of all women of reproductive age and 50% of women presenting with infertility (i.e. inability to reach a pregnancy after 12 months or more of regular unprotected sexual intercourse). A proportion of these women ultimately need assisted reproductive technology. In vitro fertilisation (IVF)/intracytoplasmic sperm injection (ICSI) are assisted reproduction techniques used to raise the chances of a pregnancy. In women with PCOS, the supra-physiological doses of gonadotrophins used for controlled ovarian hyperstimulation (COH) often result in an exaggerated ovarian response characterised by the development of a large cohort of follicles of uneven quality, retrieval of immature oocytes, and increased risk of ovarian hyperstimulation syndrome (OHSS). A potentially effective intervention for women with PCOS-related infertility involves earlier retrieval of immature oocytes at the germinal-vesicle stage followed by in vitro maturation (IVM). This is the third update of this Cochrane review on the subject (after the last update on 27 June 2018).

OBJECTIVES

To assess the benefits and harms of IVM followed by IVF or ICSI versus conventional IVF or ICSI among women with PCOS.

SEARCH METHODS

On 27 February 2023, we searched the Cochrane Gynaecology and Fertility Group Specialised Register of Controlled Trials, CENTRAL, MEDLINE, Embase, and the Open Grey database. We further searched the National Institute for Health and Care Excellence (NICE) fertility assessment and treatment guidelines. We also searched reference lists of relevant papers and Google Scholar for any additional trials.

SELECTION CRITERIA

We included randomised controlled trials (RCTs) comparing IVM before IVF or ICSI with conventional IVF or ICSI for infertile women with PCOS, irrespective of language and country of origin.

DATA COLLECTION AND ANALYSIS

Two review authors independently selected studies, assessed the risk of bias, extracted data from studies, and, where needed, attempted to contact the authors for missing data. Our primary outcomes were live birth per woman randomised and miscarriage. We performed statistical analysis using Review Manager. We assessed the certainty of the evidence using GRADE and the risk of bias using the Cochrane RoB 2 tool.

MAIN RESULTS

We found four published trials suitable for inclusion in this update. The studies involved 810 subfertile women undergoing assisted reproductive technology. Two of four were already included in the previous version of the review, were published as abstracts in international conferences, and were at high risk of bias. The two new studies were at low risk of bias in all domains and in terms of all outcomes. We implemented the random-effects model for the quantitative analyses and restricted the primary analysis to studies at low risk of bias in all domains. We are very uncertain about the effect of IVM or capacitation IVM (a new biphasic IVM system improving the developmental competence of oocytes) on live birth when compared to IVF when a GnRH antagonist protocol was applied (odds ratio (OR) 0.47, 95% confidence interval (CI) 0.17 to 1.32; I2 = 91%; 2 studies, 739 participants; very low-certainty evidence). This suggests that if the chance of live birth following standard IVF is assumed to be 45.7%, then the chance of IVM would be 12.5% to 52.6%. In contrast, IVM or capacitation IVM increases miscarriage per clinical pregnancy (where clinical pregnancy was defined as evidence of a fetal heart beat on ultrasound at seven gestational weeks) in women with PCOS when compared to IVF (OR 1.66, 95% CI 1.02 to 2.70; I2 = 0%; 2 studies, 378 clinical pregnancies; high-certainty evidence). This suggests that if the chance of miscarriage following standard IVF is assumed to be 20.1%, then the chance using IVM would be 20.4% to 40.4%. Results remained similar when using the risk ratio (RR) as the measure of effect. We are uncertain about the effect of IVM or capacitation IVM on clinical pregnancy when compared to IVF when a GnRH antagonist protocol was applied (OR 0.49, 95% CI 0.14 to 1.70; I2 = 94%; 2 studies, 739 participants; very low-certainty evidence). The results were similar after pooling the RRs. IVM or capacitation IVM results in a large reduction in the incidence of moderate or severe OHSS as compared to IVF when a GnRH antagonist protocol was applied (OR 0.08, 95% CI 0.01 to 0.67; I2 = 0%; 2 studies, 739 participants; high-certainty evidence). This suggests that if the incidence of OHSS following IVF is assumed to be 3.5%, then the incidence with IVM would be 0% to 2.4%. Also, there is probably little to no difference in preterm birth between IVM or capacitation IVM and IVF after the application of a GnRH antagonist protocol (OR 0.69, 95% CI 0.31 to 1.52; I² = 45%; 2 studies, 739 participants; moderate-certainty evidence). As for congenital anomalies, one study reported no events, while another showed an uncertain effect of IVM (OR 0.33, 95% CI 0.01 to 8.24; 1 study, 351 participants; low-certainty evidence). Results remained similar when using the RR as the measure of effect. There were no data from any of the studies for cycle cancellation, oocyte fertilisation, or subgroup analyses.

AUTHORS' CONCLUSIONS

There is continuous scientific interest in IVM, and promising data have been published. Concerning live birth and clinical pregnancy, we are very uncertain about the effect of the technique when compared to IVF after using a GnRH antagonist protocol. In contrast, high-certainty evidence shows that IVM increases miscarriage per clinical pregnancy and reduces the incidence of moderate or severe OHSS in women with PCOS compared to IVF after a GnRH antagonist protocol. Regarding the rest of the outcomes, low- to moderate-certainty evidence showed little to no difference in preterm birth and risk of congenital anomalies between the two modalities. We eagerly anticipate further evidence from high-quality trials in the field (we found five ongoing trials).

Nicotinamide riboside supplementation ameliorates ovarian dysfunction in a PCOS mouse model

Polycystic ovary syndrome (PCOS) is the leading cause of anovulatory infertility among women of reproductive age, yet the range of effective treatment options remains limited. Our previous study revealed that reduced levels of nicotinamide adenine dinucleotide (NAD+) in ovarian granulosa cells (GCs) of women with PCOS resulted in the accumulation of reactive oxygen species (ROS) and mitochondrial dysfunction. However, it is still uncertain whether increasing NAD+ levels in the ovaries could improve ovarian function in PCOS. In this study, we demonstrated that supplementation with the NAD+ precursor nicotinamide riboside (NR) prevented the decrease in ovarian NAD+ levels, normalized estrous cycle irregularities, and enhanced ovulation potential in dehydroepiandrosterone (DHEA)-induced PCOS mice. Moreover, NR supplementation alleviated ovarian fibrosis and enhanced mitochondrial function in ovarian stromal cells of PCOS mice. Furthermore, NR supplementation improved oocyte quality in PCOS mice, as evidenced by reduced abnormal mitochondrial clustering, enhanced mitochondrial membrane potential, decreased ROS levels, reduced spindle abnormality rates, and increased early embryonic development potential in fertilized oocytes. These findings suggest that supplementing with NAD+ precursors could be a promising therapeutic strategy for addressing ovarian infertility associated with PCOS.

PGC-1α participates in regulating mitochondrial function in aged sarcopenia through effects on the Sestrin2-mediated mTORC1 pathway

BACKGROUND

Mitochondrial dysregulation in skeletal myocytes is considered a major factor in aged sarcopenia. In this study, we aimed to study the effects of peroxisome proliferator-activated receptor gamma coactivator-1 alpha (PGC-1α) on Sestrin2-mediated mechanistic target of rapamycin complex 1 (mTORC1) in aged skeletal muscles.

METHODS

C2C12 myoblasts were stimulated by 50 μM 7β-hydroxycholesterol (7β-OHC) to observe the changes of DNA damage, mitochondrial membrane potential (Δψm), mitochondrial ROS and PGC-1α protein. The PGC-1α silence in the C2C12 cells was established by siRNA transfection. The levels of DNA damage, Δψm, mitochondrial ROS, Sestrin2 and p-S6K1/S6K1 proteins were observed after the PGC-1α silence in the C2C12 cells. Recombinant Sestrin2 treatment was used to observe the changes of DNA damage, Δψm, mitochondrial ROS and p-S6K1/S6K1 protein in the 7β-OHC-treated or PGC-1α siRNA-transfected C2C12 cells. Wild-type (WT) mice and muscle-specific PGC-1α conditional knockout (MKO) mice, including young and old, were used to analyse the effects of PGC-1α on muscle function and the levels of Sestrin2 and p-S6K1 in the white gastrocnemius muscles. Recombinant Sestrin2 was administrated to analyse its effects on muscle function in the old WT mice and old MKO mice.

RESULTS

7β-OHC treatment induced DNA damage, mitochondrial dysfunction and decrease of PGC-1α protein in the C2C12 cells. PGC-1α silence also induced DNA damage and mitochondrial dysfunction in the C2C12 cells. Additionally, PGC-1α silence or 7β-OHC treatment decreased the levels of Sestrin2 and p-S6K1/S6K1 protein in the C2C12 cells. Recombinant Sestrin2 treatment significantly improved the DNA damage and mitochondrial dysfunction in the 7β-OHC-treated or PGC-1α siRNA-transfected C2C12 cells. At the same age, muscle-specific PGC-1α deficiency aggravated aged sarcopenia and decreased the levels of Sestrin2 and p-S6K1 in the white gastrocnemius muscles when compared to the WT mice. Recombinant Sestrin2 treatment improved muscle function and increased p-S6K1 levels in the old two genotypes.

CONCLUSION

This research demonstrates that PGC-1α participates in regulating mitochondrial function in aged sarcopenia through effects on the Sestrin2-mediated mTORC1 pathway.

Role of the mitophagy-apoptosis axis in the pathogenesis of polycystic ovarian syndrome

AIM

Polycystic ovary syndrome (PCOS) is a common endocrine disorder characterized by menstrual irregularities, androgen excess, and polycystic ovarian morphology, but its pathogenesis remains largely unknown. This review focuses on how androgen excess influences the molecular basis of energy metabolism, mitochondrial function, and mitophagy in granulosa cells and oocytes, summarizes our current understanding of the pathogenesis of PCOS, and discuss perspectives on future research directions.

METHODS

A search of PubMed and Google Scholar databases were used to identify relevant studies for this narrative literature review.

RESULTS

Female offspring born of pregnant animals exposed to androgens recapitulates the PCOS phenotype. Abnormal mitochondrial morphology, altered expression of genes related to glycolysis, mitochondrial biogenesis, fission/fusion dynamics, and mitophagy have been identified in PCOS patients and androgenic animal models. Androgen excess causes uncoupling of the electron transport chain and depletion of the cellular adenosine 5'-triphosphate pool, indicating further impairment of mitochondrial function. A shift toward mitochondrial fission restores mitochondrial quality control mechanisms. However, prolonged mitochondrial fission disrupts autophagy/mitophagy induction due to loss of compensatory reserve for mitochondrial biogenesis. Disruption of compensatory mechanisms that mediate the quality control switch from mitophagy to apoptosis may cause a disease phenotype. Furthermore, genetic predisposition, altered expression of genes related to glycolysis and oxidative phosphorylation, or a combination of these factors may also contribute to the development of PCOS.

CONCLUSION

In conclusion, fetuses exposed to a hyperandrogenemic intrauterine environment may cause the PCOS phenotype possibly through disruption of the compensatory regulation of the mitophagy-apoptosis axis.