Epigenetic variation in neonatal tissues in infants conceived using capacitation-in vitro maturation vs. in vitro fertilization

OBJECTIVE

To investigate alterations of the global DNA methylation profile in placenta, cord blood, and neonatal buccal smears in infants conceived using in vitro maturation (IVM) with a prematuration step (capacitation-IVM [CAPA-IVM]) vs. in vitro fertilization (IVF).

DESIGN

Analysis of data from the offspring of participants in a randomized controlled trial.

SETTING

Private clinic.

PATIENTS

Forty-six women with polycystic ovary syndrome and/or high antral follicle count and their offspring (58 newborns).

INTERVENTION(S)

Women with polycystic ovary syndrome and/or a high antral follicle count participating in the clinical trial were randomized to undergo CAPA-IVM or conventional IVF.

MAIN OUTCOME MEASURE(S)

At delivery, biological samples including cord blood, placental tissue, and a neonatal buccal smear were collected. Genome-wide DNA methylation was determined using the Illumina Infinium MethylationEPIC BeadChip. Variability in methylation was also considered, and mean variances for the two treatment categories were compared.

RESULTS

In neonatal buccal smears, there were no significant differences between the CAPA-IVM and conventional IVF groups on the basis of the CpG probe after linear regression analysis using a significant cut-off of false-discovery rate <0.05 and |Δβ|≥0.05. In cord blood, only one CpG site showed a significant gain of methylation in the CAPA-IVM group. In the placenta, CAPA-IVM was significantly associated with changes in methylation at five CpG sites. Significantly more variable DNA methylation was found in five probes in the placenta, 54 in cord blood, and two in buccal smears after IVM of oocytes. In cord blood samples, 20 CpG sites had more variable methylation in the conventional IVF vs. IVM group. Isolated CpG sites showing differences in methylation in cord blood were not associated with changes in gene expression of the overlapping genes.

CONCLUSION(S)

Capacitation-IVM appeared to be associated with only a small amount of epigenetic variation in cord blood, placental tissue, and neonate buccal smears.

CLINICAL TRIAL REGISTRATION NUMBER

NCT03405701 (www.

CLINICALTRIALS

gov).

Characterization of carbohydrate metabolism in in vivo and in vitro grown and matured mouse antral follicles

Establishing an ideal human follicle culture system for oncofertility patients relies mainly on animal models since donor tissue is scarce and often of suboptimal quality. The in vitro system developed in our laboratory supports the growth of prepubertal mouse secondary follicles up to mature oocytes. Given the importance of glucose in preparing the oocyte for proper maturation, a baseline characterization of follicle metabolism both in the culture system and in vivo was carried out. Markers of glucose-related pathways (glycolysis, tricarboxylic acid (TCA) cycle, pentose phosphate pathway (PPP), polyol pathway, hexosamine biosynthesis pathway (HBP)) as well as for the antioxidant capacity were measured in the different follicle cell types by both enzymatic activities (spectrophotometric detection) and gene expression (qPCR). This study confirmed that in vivo the somatic cells, mainly granulosa, exhibit intense glycolytic activity, while oocytes perform PPP. Throughout the final maturation step, oocytes in vivo and in vitro showed steady levels for all the key enzymes and metabolites. On the other hand, ovulation triggers a boost of pyruvate and lactate uptake in cumulus cells in vivo, consumes reduced nicotinamide adenine dinucleotide phosphate (NADPH) and increases TCA cycle and small molecules antioxidant capacity (SMAC) activities, while in vitro, the metabolic upregulation in all the studied pathways is limited. This altered metabolic pattern might be a consequence of cell exhaustion because of culture conditions, impeding cumulus cells to fulfil their role in providing proper support for acquiring oocyte competence. SUMMARY SENTENCE: In vitro cultured mouse follicles exhibit altered glycolytic activity and redox metabolism in the somatic compartment during meiotic maturation.

P–439 Carbohydrate metabolism profile during oocyte final maturation reveals culture induced aberrations in in vitro grown and matured mouse antral follicles

Study question

Are there significant differences in carbohydrate metabolism trends between in vivo and in vitro grown mouse antral follicles during oocyte final maturation?

Summary answer

Glucose metabolism characterization during GV to MII transition revealed altered metabolic patterns mainly in cumulus cells of in vitro grown and matured mouse antral follicles.

What is known already

For some cancer patients fertility restoration is dependent on using efficient in vitro follicle culture systems. As human donor ovarian tissue available for research is limited, establishing such culture systems relies on data generated from animal models. The culture system previously developed in our laboratory supports in vitro growth of mouse preantral follicles with good oocyte maturation rates but lower developmental competence compared to in vivo grown oocytes. Tracking and comparing the metabolic changes after meiotic maturation in in vitro and in vivo follicles could serve as a screening tool for improving culture conditions and identifying metabolic quality markers.

Study design, size, duration

Mouse secondary follicle culture was performed. In vitro grown oocytes, their corresponding cumulus (CC) and granulosa cells (GC) were collected from antral follicles, at germinal vesicle stage (GV) on day 9, and at metaphase 2 (MII) on day 10, after hCG/EGF stimulation. In vivo age-matched controls were obtained after intraperitoneal injections with eCG for GV, or with eCG and hCG for MII. In vivo GC after ovulation were not included.

Participants/materials, setting, methods

Glucose metabolism trends were compared during final maturation between in vitro grown antral follicles and their in vivo controls. Follicles that failed to resume meiosis in vitro were also included.

Enzymatic spectrophotometric assays were used to measure glycolysis, pentose phosphate pathway (PPP), tricarboxylic acid (TCA) cycle, and the antioxidant capacity in individual cell types. Pools of 5 oocytes and corresponding somatic cells were collected, from 3 independent experiments. Unpaired t-test was performed with significance when p &lt; 0.05.

Main results and the role of chance

Important differences were detected between in vivo and in vitro conditions. GV to MII transition in in vivo follicles leads to a metabolic boost in CC as indicated by: i. significant increase in glycolysis, PPP and TCA cycle activity; ii. higher total antioxidant capacity (TAC) (p &lt; 0.05) and small molecule antioxidant capacity (SMAC) (p &lt; 0.01). After ovulation, the only significant change in oocytes was an increase in nicotinamide adenine dinucleotide phosphate (NADP+) level (p &lt; 0.01), possibly due to increased reduced-NADP recycling.

Meiotic maturation triggered no significant differences in any of the metabolic pathways for in vitro grown oocytes. Contrary to their in vivo controls, in vitro CC showed significant upregulations limited to aconitase, lactate dehydrogenase (LDH) and glutathione-s-transferase (GST) activity (p &lt; 0.05). In vitro GC showed increased G6PDH activity (p &lt; 0.05), suggesting PPP upregulation.

Significant differences were detected between in vivo GV follicles and the in vitro failed-to-mature ones. Oocytes from impaired follicles have higher NADP+ levels (p &lt; 0.0001) than their in vivo immature counterparts. CC showed higher phosphofructokinase (PFK), LDH, catalase activity and increased NADP + (p &lt; 0.01), TAC and SMAC (p &lt; 0.05) compared to in vivo GV CCs. GCs from failed-to-mature follicles have significantly higher LDH and superoxide dismutase (SOD) activity than in vivo GV GC (p &lt; 0.05).

Limitations, reasons for caution

The altered metabolic patterns described here in in vitro follicles during oocyte GV to MII transition are probably the cumulative effects of both growth and maturation in vitro.

Wider implications of the findings: We explored extensively and directly, for the first time, several enzymes and metabolites involved in follicle glucose and redox metabolism in different cell types separately. Understanding of the follicle metabolic requirements is essential for the optimization of follicle culture systems and could lead to development of oocyte quality markers.

Trial registration number

Not applicable

Reversing complete mechanical transzonal projections disruption during mouse in vitro follicle culture with unaltered oocyte competence†

In vitro oocyte growth is widely studied as an alternative fertility preservation approach. Several animal models are used to generate extensive information on this complex process regulated by the constant and dynamic interaction between the oocyte and its somatic compartment throughout follicle growth and maturation. A two-dimensional attachment mouse secondary follicle culture system was used to assess the oocyte's capacity to overcome disconnection from its somatic companions at different developmental stages for final competence acquisition. To test this, complete mechanical denudation of oocytes from preantral (PA) and early antral (EA) follicles was performed. Established endpoints were the oocyte's potential to reconnect with somatic cells and the impact of connectivity disruption on mature oocyte quality. This study proves that oocytes from PA and EA cultured mouse follicles can overcome complete denudation, restoring likely functional transzonal projections with no significant differences in meiotic and developmental competence compared with those from intact cultured follicles. These novel findings constitute good premises for developing successful strategies to rescue human oocyte competence in the context of in vitro culture approaches such as nonhuman chorionic gonadotropin triggered in vitro maturation.

Glucose metabolism characterization during mouse in vitro maturation identifies alterations in cumulus cells†

In vitro maturation (IVM) is an assisted reproduction technique with reduced hormone-related side-effects. Several attempts to implement IVM in routine practice have failed, primarily due to its relatively low efficiency compared with conventional in vitro fertilization (IVF). Recently, capacitation (CAPA)-IVM-a novel two-step IVM method-has improved the embryology outcomes through synchronizing the oocyte nuclear and cytoplasmic maturation. However, the efficiency gap between CAPA-IVM and conventional IVF is still noticeable especially in the numerical production of good quality embryos. Considering the importance of glucose for oocyte competence, its metabolization is studied within both in vivo and CAPA-IVM matured mouse cumulus-oocyte-complexes (COCs) through direct measurements in both cellular compartments, from transcriptional and translational perspectives, to reveal metabolic shortcomings within the CAPA-IVM COCs. These results confirmed that within in vivo COC, cumulus cells (CCs) are highly glycolytic, whereas oocytes, with low glycolytic activity, are deviating their glucose towards pentose phosphate pathway. No significant differences were observed in the CAPA-IVM oocytes compared with their in vivo counterparts. However, their CCs exhibited a precocious increase of glycolytic activity during the pre-maturation culture step and activity was decreased during the IVM step. Here, specific alterations in mouse COC glucose metabolism due to CAPA-IVM culture were characterized using direct measurements for the first time. Present data show that, while CAPA-IVM CCs are able to utilize glucose, their ability to support oocytes during final maturation is impaired. Future CAPA-IVM optimization strategies could focus on adjusting culture media energy substrate concentrations and/or implementing co-culture strategies.

Zika Virus Protease Cleavage of Host Protein Septin-2 Mediates Mitotic Defects in Neural Progenitors

Zika virus (ZIKV) targets neural progenitor cells in the brain, attenuates cell proliferation, and leads to cell death. Here, we describe a role for the ZIKV protease NS2B-NS3 heterodimer in mediating neurotoxicity through cleavage of a host protein required for neurogenesis. Similar to ZIKV infection, NS2B-NS3 expression led to cytokinesis defects and cell death in a protease activity-dependent fashion. Among binding partners, NS2B-NS3 cleaved Septin-2, a cytoskeletal factor involved in cytokinesis. Cleavage of Septin-2 occurred at residue 306 and forced expression of a non-cleavable Septin-2 restored cytokinesis, suggesting a direct mechanism of ZIKV-induced neural toxicity. VIDEO ABSTRACT.

Zika Virus Infects Neural Progenitors in the Adult Mouse Brain and Alters Proliferation

Zika virus (ZIKV)-related neuropathology is an important global health concern. Several studies have shown that ZIKV can infect neural stem cells in the developing brain, but infection in the adult brain has not been examined. Two areas in the adult mouse brain contain neural stem cells: the subventricular zone of the anterior forebrain and the subgranular zone of the hippocampus. Here, using 6-week-old mice triply deficient in interferon regulatory factor (IRF) as a model, we show that blood-borne ZIKV administration can lead to pronounced evidence of ZIKV infection in these adult neural stem cells, leading to cell death and reduced proliferation. Our data therefore suggest that adult as well as fetal neural stem cells are vulnerable to ZIKV neuropathology. Thus, although ZIKV is considered a transient infection in adult humans without marked long-term effects, there may in fact be consequences of exposure in the adult brain.

HDAC6 activity is a non-oncogene addiction hub for inflammatory breast cancers

INTRODUCTION

Inflammatory breast cancer (IBC) is the most lethal form of breast cancers with a 5-year survival rate of only 40 %. Despite its lethality, IBC remains poorly understood which has greatly limited its therapeutic management. We thus decided to utilize an integrative functional genomic strategy to identify the Achilles' heel of IBC cells.

METHODS

We have pioneered the development of genetic tools as well as experimental and analytical strategies to perform RNAi-based loss-of-function studies at a genome-wide level. Importantly, we and others have demonstrated that these functional screens are able to identify essential functions linked to certain cancer phenotypes. Thus, we decided to use this approach to identify IBC specific sensitivities.

RESULTS

We identified and validated HDAC6 as a functionally necessary gene to maintain IBC cell viability, while being non-essential for other breast cancer subtypes. Importantly, small molecule inhibitors for HDAC6 already exist and are in clinical trials for other tumor types. We thus demonstrated that Ricolinostat (ACY1215), a leading HDAC6 inhibitor, efficiently controls IBC cell proliferation both in vitro and in vivo. Critically, functional HDAC6 dependency is not associated with genomic alterations at its locus and thus represents a non-oncogene addiction. Despite HDAC6 not being overexpressed, we found that its activity is significantly higher in IBC compared to non-IBC cells, suggesting a possible rationale supporting the observed dependency.

CONCLUSION

Our finding that IBC cells are sensitive to HDAC6 inhibition provides a foundation to rapidly develop novel, efficient, and well-tolerated targeted therapy strategies for IBC patients.