Cellular senescence of granulosa cells in the pathogenesis of polycystic ovary syndrome

Polycystic ovary syndrome (PCOS) is one of the most common endocrine disorders in women of reproductive age, but its pathology has not been fully characterized and the optimal treatment strategy remains unclear. Cellular senescence is a permanent state of cell-cycle arrest that can be induced by multiple stresses. Senescent cells contribute to the pathogenesis of various diseases, owing to an alteration in secretory profile, termed 'senescence-associated secretory phenotype' (SASP), including with respect to pro-inflammatory cytokines. Senolytics, a class of drugs that selectively eliminate senescent cells, are now being used clinically, and a combination of dasatinib and quercetin (DQ) has been extensively used as a senolytic. We aimed to investigate whether cellular senescence is involved in the pathology of PCOS and whether DQ treatment has beneficial effects in patients with PCOS. We obtained ovaries from patients with or without PCOS, and established a mouse model of PCOS by injecting dehydroepiandrosterone. The expression of the senescence markers p16INK4a, p21, p53, γH2AX, and senescence-associated β-galactosidase (SA-β-gal); and the SASP-related factor interleukin (IL)-6; were significantly higher in the ovaries of patients with PCOS and PCOS mice than in controls. To evaluate the effects of hyperandrogenism and DQ on cellular senescence in vitro, we stimulated cultured human granulosa cells (GCs) with testosterone and treated them with DQ. The expression of markers of senescence and a SASP-related factor was increased by testosterone, and DQ reduced this increase. DQ reduced the expression of markers of senescence and a SASP-related factor in the ovaries of PCOS mice and improved their morphology. These results indicate that cellular senescence occurs in PCOS. Hyperandrogenism causes cellular senescence in GCs in PCOS and senolytic treatment reduces the accumulation of senescent GCs and improves ovarian morphology under hyperandrogenism. Thus, DQ might represent a novel therapy for PCOS.

Effects of the prenatal and postnatal nurturing environment on the phenotype and gut microbiota of mice with polycystic ovary syndrome induced by prenatal androgen exposure: a cross-fostering study

The gut microbiome is implicated in the pathogenesis of polycystic ovary syndrome (PCOS), and prenatal androgen exposure is involved in the development of PCOS in later life. Our previous study of a mouse model of PCOS induced by prenatal dihydrotestosterone (DHT) exposure showed that the reproductive phenotype of PCOS appears from puberty, followed by the appearance of the metabolic phenotype after young adulthood, while changes in the gut microbiota was already apparent before puberty. To determine whether the prenatal or postnatal nurturing environment primarily contributes to these changes that characterize prenatally androgenized (PNA) offspring, we used a cross-fostering model to evaluate the effects of changes in the postnatal early-life environment of PNA offspring on the development of PCOS-like phenotypes and alterations in the gut microbiota in later life. Female PNA offspring fostered by normal dams (exposed to an abnormal prenatal environment only, fostered PNA) exhibited less marked PCOS-like phenotypes than PNA offspring, especially with respect to the metabolic phenotype. The gut microbiota of the fostered PNA offspring was similar to that of controls before adolescence, but differences between the fostered PNA and control groups became apparent after young adulthood. In conclusion, both prenatal androgen exposure and the postnatal early-life environment created by the DHT injection of mothers contribute to the development of PCOS-like phenotypes and the alterations in the gut microbiota that characterize PNA offspring. Thus, both the pre- and postnatal environments represent targets for the prevention of PCOS and the associated alteration in the gut microbiota in later life.

A genome-wide perspective of the maternal mRNA translation program during oocyte development

Transcriptional and post-transcriptional regulations control gene expression in most cells. However, critical transitions during the development of the female gamete relies exclusively on regulation of mRNA translation in the absence of de novo mRNA synthesis. Specific temporal patterns of maternal mRNA translation are essential for the oocyte progression through meiosis, for generation of a haploid gamete ready for fertilization and for embryo development. In this review, we will discuss how mRNAs are translated during oocyte growth and maturation using mostly a genome-wide perspective. This broad view on how translation is regulated reveals multiple divergent translational control mechanisms required to coordinate protein synthesis with progression through the meiotic cell cycle and with development of a totipotent zygote.

Multiple intersecting pathways are involved in the phosphorylation of CPEB1 to activate translation during mouse oocyte meiosis

The RNA-binding protein cytoplasmic polyadenylation element binding 1 (CPEB1) plays a fundamental role in the regulation of mRNA translation in oocytes. However, the nature of protein kinase cascades modulating the activity of CPEB1 is still a matter of controversy. Using genetic and pharmacological tools and detailed time courses, here we have reevaluated the relationship between CPEB1 phosphorylation and the activation of translation during mouse oocyte maturation. We show that both the CDK1/MAPK and AURKA/PLK1 pathways converge on the phosphorylation of CPEB1 during prometaphase. Only inactivation of the CDK1/MAPK pathway disrupts translation, while inactivation of either pathway leads to CPEB1 stabilization. However, stabilization of CPEB1 induced by inactivation of the AURKA/PLK1 does not affect translation, indicating that destabilization/degradation can be dissociated from translational activation. The accumulation of the endogenous CCNB1 protein closely recapitulates the translation data. These findings support the overarching hypothesis that the activation of translation in prometaphase in mouse oocytes relies on a CDK1-dependent CPEB1 phosphorylation, and this translational activation precedes CPEB1 destabilization.

The Role of Cellular Senescence in Cyclophosphamide-Induced Primary Ovarian Insufficiency

Young female cancer patients can develop chemotherapy-induced primary ovarian insufficiency (POI). Cyclophosphamide (Cy) is one of the most widely used chemotherapies and has the highest risk of damaging the ovaries. Recent studies elucidated the pivotal roles of cellular senescence, which is characterized by permanent cell growth arrest, in the pathologies of various diseases. Moreover, several promising senolytics, including dasatinib and quercetin (DQ), which remove senescent cells, are being developed. In the present study, we investigated whether cellular senescence is involved in Cy-induced POI and whether DQ treatment rescues Cy-induced ovarian damage. Expression of the cellular senescence markers p16, p21, p53, and γH2AX was upregulated in granulosa cells of POI mice and in human granulosa cells treated with Cy, which was abrogated by DQ treatment. The administration of Cy decreased the numbers of primordial and primary follicles, with a concomitant increase in the ratio of growing to dormant follicles, which was partially rescued by DQ. Moreover, DQ treatment significantly improved the response to ovulation induction and fertility in POI mice by extending reproductive life. Thus, cellular senescence plays critical roles in Cy-induced POI, and targeting senescent cells with senolytics, such as DQ, might be a promising strategy to protect against Cy-induced ovarian damage.

Roles of endoplasmic reticulum stress in the pathophysiology of polycystic ovary syndrome

Polycystic ovary syndrome (PCOS) is the most common endocrine disorder among reproductive-age women, affecting up to 15% of women in this group, and the most common cause of anovulatory infertility. Although its etiology remains unclear, recent research has revealed the critical role of endoplasmic reticulum (ER) stress in the pathophysiology of PCOS. ER stress is defined as a condition in which unfolded or misfolded proteins accumulate in the ER because of an imbalance in the demand for protein folding and the protein-folding capacity of the ER. ER stress results in the activation of several signal transduction cascades, collectively termed the unfolded protein response (UPR), which regulates various cellular activities. In principle, the UPR restores homeostasis and keeps the cell alive. However, if the ER stress cannot be resolved, it induces programmed cell death. ER stress has recently been recognized to play diverse roles in both physiological and pathological conditions of the ovary. In this review, we summarize current knowledge of the roles of ER stress in the pathogenesis of PCOS. ER stress pathways are activated in the ovaries of both a mouse model of PCOS and in humans, and local hyperandrogenism in the follicular microenvironment associated with PCOS is responsible for activating these. The activation of ER stress contributes to the pathophysiology of PCOS through multiple effects in granulosa cells. Finally, we discuss the potential for ER stress to serve as a novel therapeutic target for PCOS.

RF10 | PMON241 Temporal Changes in Phenotype and Gut microbiota in PCOS Mouse Model Induced by Prenatal Androgen Exposure

PCOS is a complex multigenic disorder with strong epigenetic and environmental influence. Previous reports have suggested that fetal over-exposure to androgens contributes to the development of PCOS after birth. On the other hands, recent studies on both human and rodent models of PCOS have demonstrated the relationship between PCOS and gut microbiome in adulthood. Furthermore, gut microbiome in obese adolescent with PCOS are different from obese adolescent without PCOS. However, the mechanism has not been revealed and it is unclear which events appear first, PCOS phenotypes or gut microbiome. We wondered if prenatal androgen exposure leads gut microbial dysbiosis early in life and is associated with the development of PCOS in later life. To test this hypothesis, we examined the temporal changes in the phenotypes of PCOS and gut microbiome using prenatally androgenized (PNA) model mice, an well-established model of PCOS. PNA model was generated by subcutaneously injecting pregnant dams with dehydroepiandrosterone (DHT) on days 16, 17, and 18 of gestation. Phenotypes and gut microbiome activity were compared between PCOS model mice (n=12/group) and control mice (n=10/group) at each developmental stage of 4 weeks (prepuberty), 6 weeks (puberty), 8 weeks (adolescent), 12 weeks (young adulthood), and 16 weeks (adulthood), respectively. The determinants for PCOS development are onset of puberty, estrous cycle, morphology of ovaries, serum testosterone levels, body weight, the size of parametrial adipocytes, and insulin resistance. For evaluation of gut microbiome, next generation sequencing and bioinformatics analysis of 16S rRNA genes were performed on obtained DNA from mouse fecal samples. PNA groups resulted in delayed puberty onset, disrupted estrous cycle, and increased testosterone levels from 6 weeks. Increased atretic antral follicles were observed in PNA groups at 6, 12, and 16 weeks. Additionally, PNA groups showed increased body weight, hypertrophy of parametrial adipocytes, and insulin resistant from 12 weeks. As for gut microbiome, PNA exhibited altered alpha-diversity from 8 weeks and beta-diversity at 8 weeks. Composition of gut microbiome was already altered from 4 weeks. At phylum level, Firmicutes phylum are significantly increased in PNA groups at 4 and 8, and decreased at 16 weeks. Actinobacteria phylum showed significant decrease at 6 and 8 weeks in PNA groups. At genus level, relative abundance of several bacterial taxa differed significantly between control and PNA groups; Allobaculum, Adlercreutzia which produce equol, Roseburia which produce butyric acid, and Sutterella were significantly decreased in PNA groups at multiple stages of development. In conclusion, our findings suggest that the alteration of gut microbiome appears simultaneously or even earlier than the presence of PCOS phenotypes, and that normalizing microbiome could improve pathologic condition of PCOS. In addition, early intervention of gut microbiome might indicate preventive care for women at high-risk of developing PCOS.

Presentation: Saturday, June 11, 2022 1:18 p.m. - 1:23 p.m., Monday, June 13, 2022 12:30 p.m. - 2:30 p.m.

P-610 Endoplasmic reticulum stress-induced Notch signaling stimulates cumulus-oocyte complex expansion in PCOS

Study question

Does endoplasmic reticulum (ER) stress and Notch signaling affect cumulus-oocyte complex (COC) expansion in pathophysiology of polycystic ovary syndrome (PCOS)?

Summary answer

Notch signaling is induced via activation of ER stress in granulosa cells (GCs) of PCOS and stimulates COC expansion that is abrogated by Notch inhibition.

What is known already

PCOS presents a variety of symptoms including ovarian dysfunction which is caused by various local factors in follicular microenvironment; among them, ER stress and following activation of unfolded protein response are critical, causing ovarian fibrosis, growth arrest of antral follicles and other ovarian dysfunctions. While Notch signaling pathway plays an important role of various ovarian functions such as ovarian development, follicle growth, luteinization and steroid hormone synthesis, the potential interaction between Notch signaling and ER stress in ovarian function is not determined.

Study design, size, duration

To examine expression levels of Notch signaling, ovaries and granulosa-lutein cells (GLCs) were collected from PCOS patients undergoing surgery or IVF. Human GLCs were collected from follicular fluid of IVF patients and cultured under ER-stressed condition. COCs obtained from PMSG-primed mice were subjected to examine the in vitro effects of ER stress activation and Notch inhibition on COC expansion. To examine the in vivo effects of Notch inhibition, dehydroepiandrosterone-induced PCOS mouse model was used.

Participants/materials, setting, methods

The expression levels of Notch signaling in ovaries and GLCs were investigated by immunohistochemistry and real time qPCR. To examine whether Notch signaling is activated by ER stress, human GLCs were incubated with ER stress inducer or inhibitor and ATF4 was knocked down by RNA interference. To investigate COC expansion level, murine COCs were cultured under ER stress condition with/without Notch signaling inhibitor. The COCs were collected from PCOS mice treated with/without Notch inhibitor.

Main results and the role of chance

We found that the expression levels of Notch2 and Hey2, a transcription factor activated by Notch signaling, were upregulated in GCs of antral follicles from PCOS patients and PCOS mice by using immunohistochemical analysis. Similarly, mRNA levels of these genes were higher in GLCs from PCOS patients than those from control patients. Notch signaling was induced in cultured human GLCs incubated with an ER stress inducer, tunicamycin; the effect was abrogated by incubation with an ER stress inhibitor, tauroursodeoxycholic acid (TUDCA), or knockdown of activating transcription factor 4 (ATF4, a transcription factor induced by ER stress). These findings suggest that Notch signaling is induced by ER stress via ATF4 pathway in human GCs. Measuring under a microscope, the area of expanded COCs was increased in cultured murine COCs incubated with tunicamycin, while this stimulatory effect of tunicamycin was abrogated by adding a Notch signaling inhibitor, DAPT. The area of expanded COCs obtained from PCOS model mice was increased compared to control mice, while administration of DAPT to these mice reduced the area. These results suggest that ER stress-induced Notch signaling stimulate COC expansion contributing PCOS pathophysiology.

Limitations, reasons for caution

COC expansion area was measured only in PCOS model mouse; it is unknown whether COC expansion is induced in PCOS patients. This point requires further investigation in PCOS patients.

Wider implications of the findings

Our findings suggest that ER stress-induced Notch signaling affects COC expansion, associated with ovulatory dysfunction in PCOS. The detailed understandings of PCOS pathophysiology may be beneficial for substantial clinical implications and inhibition of ER stress or Notch signaling may serve as a novel therapeutic approach for PCOS.

Trial registration number

This study was supported by Grants-in-Aid for Scientific Research from the Japan Society for the Promotion of Science (JSPS) (19k09749, 19k24045, 19k24021, 21k16808, 21j12871,), a grant from the Takeda Science Foundation, a grant from The Tokyo Society of Medical Science, a grant from The Japan Society of Fertility Preservation, and a grant from The Japan Society for Menopause and Women’s Health (JMWH) (a JMWH Bayer Grant).

The possible effects of the Japan Society of Clinical Oncology Clinical Practice Guidelines 2017 on the practice of fertility preservation in female cancer patients in Japan

Purpose

In 2017, the first guidelines for fertility preservation in cancer patients were published in Japan. However, the impact of the guidelines remains unknown. Therefore, the authors conducted a nationwide survey on cryopreservation procedures in the period from shortly before to after publication of the guidelines (2016–2019) and compared the results with our previous survey (2011–2015). The authors also surveyed reproductive specialists’ awareness of the guidelines and implementation problems.

Methods

The authors sent a questionnaire to 618 assisted reproductive technology facilities certified by the Japanese Society of Obstetrics and Gynecology.

Results

The authors received responses from 395 institutions (63.8%). Among them, 144 institutions conducted cryopreservation for cancer patients (vs. 126 in 2011–2015) and performed 2537 embryo or oocyte and 178 ovarian tissue cryopreservation procedures (vs. 1085 and 122, respectively). Compared with the previous period, indications were more varied and protocols for controlled ovarian stimulation were more standardized. Reproductive specialists’ interest in oncofertility was high, but many reported three main difficulties: selecting a treatment method, storing samples in the long term, and securing the necessary human resources.

Conclusions

The practice of fertility preservation in cancer patients in Japan has been considerably affected by the first Japanese guidelines.

Temporal relationship between alterations in the gut microbiome and the development of polycystic ovary syndrome-like phenotypes in prenatally androgenized female mice

It has been recently recognized that prenatal androgen exposure is involved in the development of polycystic ovary syndrome (PCOS) in adulthood. In addition, the gut microbiome in adult patients and rodents with PCOS differs from that of healthy individuals. Moreover, recent studies have suggested that the gut microbiome may play a causative role in the pathogenesis of PCOS. We wondered whether prenatal androgen exposure induces gut microbial dysbiosis early in life and is associated with the development of PCOS in later life. To test this hypothesis, we studied the development of PCOS-like phenotypes in prenatally androgenized (PNA) female mice and compared the gut microbiome of PNA and control offspring from 4 to 16 weeks of age. PNA offspring showed a reproductive phenotype from 6 weeks and a metabolic phenotype from 12 weeks of age. The α-diversity of the gut microbiome of the PNA group was higher at 8 weeks and lower at 12 and 16 weeks of age, and the β-diversity differed from control at 8 weeks. However, a significant difference in the composition of gut microbiome between the PNA and control groups was already apparent at 4 weeks. Allobaculum and Roseburia were less abundant in PNA offspring, and may therefore be targets for future interventional studies. In conclusion, abnormalities in the gut microbiome appear as early as or even before PCOS-like phenotypes develop in PNA mice. Thus, the gut microbiome in early life is a potential target for the prevention of PCOS in later life.

P–632 Examination of temporal changes in phenotype and gut microbiome during the process of growth in polycystic ovary syndrome (PCOS) model induced by prenatal androgen exposure

Study question

From when do abnormality in gut microbiome and phenotypes of PCOS appear during the process of growth?

Summary answer

Reproductive phenotypes of PCOS appear from 6 weeks and metabolic phenotypes from 12 weeks onward. Alteration in gut microbiome appears as early as 4 weeks.

What is known already

The etiology of PCOS remains largely unknown, however PCOS is considered as a complex multigenic disorder with strong epigenetic and environmental influence. Previous studies have suggested that fetal over-exposure to androgens could be the main factor of the development of PCOS after birth. On the other hands, recent studies on both human and PCOS rodent models have demonstrated the association between PCOS and alteration of gut microbiome in adulthood. Furthermore, it was recently reported that gut microbiome in obese adolescent with PCOS is different from obese adolescent without PCOS.

Study design, size, duration

A rodent PCOS model induced by prenatal dehydroepiandrosterone (DHT) exposure was applied to this study. Phenotypes and gut microbiome were compared between PCOS model mice (n = 12/group) and control mice (n = 10/group) at each stage of growth; 4 weeks (prepuberty), 6 weeks (puberty), 8 weeks (adolescent), 12 weeks (young adult), and 16 weeks (adult). The determinants for PCOS phenotypes are onset of puberty, estrous cycle, morphology of ovaries, serum testosterone level, body weight, and insulin resistance.

Participants/materials, setting, methods

Pregnant dams were subcutaneously injected on days of 16, 17, and 18 of gestation with either sesame oil for control groups or sesame oil containing 250µg of DHT for prenatal DHT groups. The evaluation of PCOS phenotypes and gut microbiome in female offspring were performed at each stage of growth. For examination of gut microbiota, next generation sequencing and bioinformatics analysis of 16S rRNA genes were performed on DNA extracted from mouse fecal samples.

Main results and the role of chance

Prenatal DHT mice exhibited delayed puberty onset, disrupted estrous cycle, and significantly increased testosterone levels from 6 weeks onward. Significantly increased atretic antral follicles were observed in prenatal DHT mice at 6, 12, and 16 weeks. Prenatal DHT mice showed significantly decreased body weight at 4, 6, 8 weeks and increased body weight from 12 weeks onward. As for gut microbiome, alpha-diversity was significantly different between control and prenatal DHT mice from 8 weeks onward and beta-diversity was significantly different at 6 and 8 weeks. Altered composition of gut microbiota was observed as early as 4 weeks. At phylum level, Firmicutes are significantly increased in prenatal DHT mice at 4 and 8 weeks and decreased at 16 weeks. Actinobacteria phylum showed significant decrease at 6 and 8 weeks in prenatal DHT mice. At genus level, relative abundance of several bacterial taxa significantly differed between control and prenatal DHT mice; some taxa, such as Allobaculum, Adlercreutzia, Bilophila, Clostridium, Gemella, Gemmiger, Roseburia, Ruminococcus, Staphylococcus, and Sutterella, exhibited constant increase or decrease in prenatal DHT mice during the process of growth. Interestingly, Roseburia was never detected in prenatal DHT mice, while approximately half of control mice harbored Roseburia at 12 and 16 weeks.

Limitations, reasons for caution

It is not clearly determined whether alteration in gut microbiome is cause or result of PCOS development, although the changes in gut microbiome seemed to precede the appearance of typical PCOS phenotypes in the present study. Mouse model does not completely recapitulate human PCOS.

Wider implications of the findings: Our findings suggest that prenatal androgen exposure causes alteration of gut microbiome from pre-puberty onward, even before PCOS phenotypes become apparent. Intervention for girls at risk of PCOS with pre/pro-biotics may prevent them from developing PCOS in future.

Trial registration number

Not applicable

Upregulation of Aryl Hydrocarbon Receptor in Granulosa Cells by Endoplasmic Reticulum Stress Contributes to the PCOS Pathophysiology

Studies have demonstrated that endocrine disrupting chemicals (EDC) are involved in the pathophysiology of PCOS, and aryl hydrocarbon receptor (AHR) mediates the cellular effect of EDC by inducing xenobiotic metabolizing enzymes including cytochrome P450 1B1 (CYP1B1). However, recent studies suggest the novel role of AHR in various diseases, including obesity and cancer progression, independent from the EDC metabolism. We previously demonstrated that endoplasmic reticulum (ER) stress, a newly recognized local factor, contributes to PCOS pathology by affecting diverse functions of granulosa cells. We hypothesized that ER stress induces the expression of AHR and activates its downstream signaling in granulosa cells, irrespective of the presence of EDCs, thereby promoting PCOS pathogenesis. At first, we determined the upregulation of AHR, AHR nuclear translocator (ARNT), and AHR target gene cytochrome P450 1B1 (CYP1B1) in the granulosa cells of PCOS patients and model mice by immunohistochemical staining and qPCR. We examined CYP1B1 as a representative AHR target gene. Treatment of cultured human granulosa-lutein cells (GLCs) with tunicamycin (ER stress inducer) upregulated the expression of AHR, ARNT and CYP1B1. Knockdown of AHR decreased the tunicamycin-induced expression and activity of CYP1B1, suggesting the intermediary role of AHR in upregulation of AHR activity by ER stress. To confirm the role of AHR in vivo, we administered the AHR antagonist CH223191 to PCOS model mice. The administration of the antagonist restored estrous cycling and decreased the number of atretic antral follicles, concomitant with downregulation of AHR and CYP1B1 in granulosa cells. Taken together, this study indicates that AHR and downstream signaling are activated by ER stress in GLCs of PCOS. Moreover, downregulation of local AHR expression and activation restores a normal reproductive phenotype in a PCOS mouse model. Our findings demonstrate that AHR activated by ER stress in the follicular microenvironment contributes to PCOS pathology, and that AHR represents a novel therapeutic target for PCOS.

Induction of aryl hydrocarbon receptor in granulosa cells by endoplasmic reticulum stress contributes to pathology of polycystic ovary syndrome

Recent studies have uncovered the critical role of aryl hydrocarbon receptor (AHR) in various diseases, including obesity and cancer progression, independent of its previously identified role as a receptor for endocrine-disrupting chemicals (EDCs). We previously showed that endoplasmic reticulum (ER) stress, a newly recognized local factor in the follicular microenvironment, is activated in granulosa cells from patients with polycystic ovary syndrome (PCOS) and a mouse model of the disease. By affecting diverse functions of granulosa cells, ER stress contributes to PCOS pathology. We hypothesized that expression of AHR and activation of its downstream signaling were upregulated by ER stress in granulosa cells, irrespective of the presence of EDCs, thereby promoting PCOS pathogenesis. In this study, we found that AHR, AHR nuclear translocator (ARNT), and AHR target gene cytochrome P450 1B1 (CYP1B1) were upregulated in the granulosa cells of PCOS patients and model mice. We examined CYP1B1 as a representative AHR target gene. AHR and ARNT were upregulated by ER stress in human granulosa-lutein cells (GLCs), resulting in an increase in the expression and activity of CYP1B1. Administration of the AHR antagonist CH223191 to PCOS mice restored estrous cycling and decreased the number of atretic antral follicles, concomitant with downregulation of AHR and CYP1B1 in granulosa cells. Taken together, our findings indicate that AHR activated by ER stress in the follicular microenvironment contributes to PCOS pathology, and that AHR represents a novel therapeutic target for PCOS.

Activation of endoplasmic reticulum stress mediates oxidative stress-induced apoptosis of granulosa cells in ovaries affected by endometrioma

Endometriosis exerts detrimental effects on ovarian physiology and compromises follicular health. Granulosa cells from patients with endometriosis are characterized by increased apoptosis, as well as high oxidative stress. Endoplasmic reticulum (ER) stress, a local factor closely associated with oxidative stress, has emerged as a critical regulator of ovarian function. We hypothesized that ER stress is activated by high oxidative stress in granulosa cells in ovaries with endometrioma and that this mediates oxidative stress-induced apoptosis. Human granulosa-lutein cells (GLCs) from patients with endometrioma expressed high levels of mRNAs associated with the unfolded protein response (UPR). In addition, the levels of phosphorylated ER stress sensor proteins, inositol-requiring enzyme 1 (IRE1) and double-stranded RNA-activated protein kinase-like ER kinase (PERK), were elevated in granulosa cells from patients with endometrioma. Given that ER stress results in phosphorylation of ER stress sensor proteins and induces UPR factors, these findings indicate that these cells were under ER stress. H2O2, an inducer of oxidative stress, increased expression of UPR-associated mRNAs in cultured human GLCs, and this effect was abrogated by pretreatment with tauroursodeoxycholic acid (TUDCA), an ER stress inhibitor in clinical use. Treatment with H2O2 increased apoptosis and the activity of the pro-apoptotic factors caspase-8 and caspase-3, both of which were attenuated by TUDCA. Our findings suggest that activated ER stress induced by high oxidative stress in granulosa cells in ovaries with endometrioma mediates apoptosis of these cells, leading to ovarian dysfunction in patients with endometriosis.

Endoplasmic reticulum stress: a key regulator of the follicular microenvironment in the ovary

Intra-ovarian local factors regulate the follicular microenvironment in coordination with gonadotrophins, thus playing a crucial role in ovarian physiology as well as pathological states such as polycystic ovary syndrome (PCOS). One recently recognized local factor is endoplasmic reticulum (ER) stress, which involves the accumulation of unfolded or misfolded proteins in the ER related to various physiological and pathological conditions that increase the demand for protein folding or attenuate the protein-folding capacity of the organelle. ER stress results in activation of several signal transduction cascades, collectively termed the unfolded protein response (UPR), which affect a wide variety of cellular functions. Recent studies have revealed diverse roles of ER stress in physiological and pathological conditions in the ovary. In this review, we summarize the most current knowledge of the regulatory roles of ER stress in the ovary, in the context of reproduction. The physiological roles of ER stress and the UPR in the ovary remain largely undetermined. On the contrary, activation of ER stress is known to impair follicular and oocyte health in various pathological conditions; moreover, ER stress also contributes to the pathogenesis of several ovarian diseases, including PCOS. Finally, we discuss the potential of ER stress as a novel therapeutic target. Inhibition of ER stress or UPR activation, by treatment with existing chemical chaperones, lifestyle intervention, or the development of small molecules that target the UPR, represents a promising therapeutic strategy.

Accumulation of advanced glycation end products in follicles is associated with poor oocyte developmental competence

Advanced glycation end products (AGEs) affect the follicular microenvironment. The close relationship between AGEs, proinflammatory cytokine production and activation of the unfolded protein response (UPR), which involves activating transcription factor 4 (ATF4), is crucial for regulation of various cellular functions. We examined whether accumulation of AGEs in follicles was associated with proinflammatory cytokine production and activation of the UPR in granulosa cells and decreased oocyte developmental competence. Concentrations of AGEs, soluble receptor for AGE (sRAGE), interleukin (IL)-6 and IL-8 in follicular fluid (FF) were examined by ELISAs in 50 follicles. mRNA expression of ATF4, IL-6 and IL-8 in cumulus cells (CCs) were examined by quantitative RT-PCR in 77 samples. Cultured human granulosa-lutein cells (GLCs) were treated with AGE-bovine serum albumin (BSA) alone or following transfection of ATF4-targeting small interfering RNA. The AGE concentration and the AGE/sRAGE ratio in FF were significantly higher in follicles containing oocytes that developed into poor-morphology embryos (group I) than those with good-morphology embryos (group II). When compared with sibling follicles from the same patients, the AGE/sRAGE and concentrations of IL-6 and IL-8 in FF, as well as ATF4, IL-6 and IL-8 mRNA expression in CCs, were significantly higher in group I follicles than group II. AGE treatment increased mRNA expression of ATF4, IL-6 and IL-8 in cultured GLCs. Knockdown of ATF4 abrogated the stimulatory effects of AGE on mRNA expression and protein secretion of IL-6 and IL-8. Our findings support the idea that accumulation of AGEs in follicles reduces oocyte competence by triggering inflammation via activation of ATF4 in the follicular microenvironment.

Inhibition of autophagy in theca cells induces CYP17A1 and PAI-1 expression via ROS/p38 and JNK signalling during the development of polycystic ovary syndrome

Polycystic ovary syndrome (PCOS) is a clinical syndrome characterized by hyperandrogenism, oligo/anovulation, and polycystic ovary. Autophagy is an intracellular system that degrades cytosolic proteins and organelles. The relationship between autophagy and PCOS has not been clarified. We found that p62 and ubiquitin were significantly increased in theca cells of women with PCOS using immunohistochemistry. Autophagy inhibition by palmitic acid and chloroquine in bovine theca cells increased p62 and ubiquitin and induced the expression of cytochrome P450 17A1 (CYP17A1) and plasminogen activator inhibitor-1 (PAI-1) mRNA. Furthermore, palmitic acid and chloroquine exposure significantly increased reactive oxygen species (ROS) and activated p38 and c-Jun N-terminal kinase (JNK). Inhibition of p38 and JNK significantly reduced CYP17A1 and PAI-1 mRNA expression. We showed that inhibition of autophagy in theca cells may have contributed to the pathogenesis of PCOS, based on CYP17A1 and PAI-1 mRNA expression via the ROS/p38 and JNK signalling pathways.

MON-033 Androgen Increases the Accumulation of Advanced Glycation End Products in Granulosa Cells by Activating ER Stress in PCOS

Polycystic ovarian syndrome (PCOS) is associated with hyperandrogenism. Previously we found that androgen activated endoplasmic reticulum (ER) stress in granulosa cells of antral follicles in PCOS, contributing to ovarian fibrosis (1) and growth arrest of antral follicles (2). In addition, recent studies demonstrated the accumulation of advanced glycation end products (AGEs) in granulosa cells from PCOS patients, which contribute to its pathology. Based on these findings, we hypothesized that androgen upregulates the expression of the receptor for AGEs (RAGE) in granulosa cells of antral follicles by activating ER stress. This in turn, increases the accumulation of AGEs in these cells. In the present study, we found that testosterone induced the expression of RAGE and accumulation of AGE in cultured human granulosa-lutein cells (GLCs). These effects were inhibited with the treatment of tauroursodeoxycholic acid (TUDCA), a clinically available ER stress inhibitor agent. Knockdown of the transcription factor C/EBP homologous protein (CHOP), an unfolded protein response (UPR) factor activated by ER stress, inhibited the testosterone-induced RAGE expression and AGE accumulation. Pretreatment with flutamide, as well as knockdown of androgen receptor decreased the testosterone-induced RAGE expression. Expression of RAGE was increased in GLCs obtained from patients with PCOS. Concomitantly, the expression of RAGE and the accumulation of AGE was increased in granulosa cells of antral follicles from PCOS patients and dehydroepiandrosterone (DHEA)-induced PCOS mice. Administration of the RAGE inhibitor, FPS-ZM1 or TUDCA to PCOS mice, reduced the expression of RAGE and the accumulation of AGE in granulosa cells of antral follicles, accompanied by a reduction of atretic follicles and improvement in the estrous cycle. In summary, our findings indicate that hyperandrogenism in PCOS increases the expression of RAGE and accumulation of AGEs in the ovary by activating ER stress. The potential therapeutic benefit of targeting the AGE-RAGE system, either with a RAGE inhibitor or an ER stress inhibitor agents, may serve as a novel approach for the treatment of PCOS. (1) Takahashi et al. Sci Rep. 2017;7(1):10824. (2) Azhary et al. Endocrinol. 2019;160(1):119–132

MON-027 Activation of Endoplasmic Reticulum Stress Mediates Oxidative Stress-Induced Apoptosis of Granulosa Cells in Ovaries Affected by Endometrioma

Endometriosis exerts detrimental effects on ovarian physiology and compromises follicular health. Granulosa cells of endometriosis patients are characterized by increased apoptosis, as well as high oxidative stress. Among several pathophysiologic factors associated with endometriosis, it is expected that oxidative stress contributes to the induction of apoptosis in granulosa cells, although the underlying mechanism remains unclear. Endoplasmic reticulum (ER) stress, a local factor closely associated with oxidative stress, has emerged as a critical regulator of ovarian function. We hypothesized that ER stress is activated by high oxidative stress in granulosa cells in ovaries with endometrioma and mediates oxidative stress-induced apoptosis. Ovaries from patients with endometrioma and control were collected to determine apoptosis, oxidative stress and ER stress by TUNEL, immunohistochemical staining of 8-OHdG and ER stress sensors, respectively. Human granulosa-lutein cells (GLCs) obtained from IVF patients were cultured with H2O2 (an oxidative stress inducer) or tauroursodeoxycholic acid (TUDCA, an ER stress inhibitor in clinical use) to assess apoptosis and ER stress by quantitative PCR and FACS. Activity of pro-apoptotic factors was determined by caspase-8 activity assay and western blotting for cleaved caspase-3. Human GLCs from patients with endometrioma expressed up to two times higher level of mRNAs associated with the unfolded protein response (UPR), including ATF4, ATF6, the spliced form of XBP1, HSPA5, and CHOP. In addition, the levels of phosphorylated ER stress sensor proteins, IRE1 and PERK, were elevated. Given that ER stress results in phosphorylation of ER stress sensor proteins and induces UPR factors, these findings indicate that these cells were under ER stress. H2O2 increased expression of UPR-associated mRNAs in cultured human GLCs, and this effect was abrogated by pre-treatment with TUDCA. Treatment with H2O2 increased apoptosis and the activity of pro-apoptotic factors caspase-8 and caspase-3, both of which were attenuated by TUDCA. Our findings suggest that activated ER stress induced by high oxidative stress in granulosa cells in ovaries with endometrioma mediates apoptosis of these cells, leading to ovarian dysfunction in endometriosis patients. Targeting ER stress with currently clinically available ER stress inhibitors, or with these agents in combination with antioxidants, may serve as a novel strategy for rescuing endometriosis-associated ovarian dysfunction.

Androgens Increase Accumulation of Advanced Glycation End Products in Granulosa Cells by Activating ER Stress in PCOS

Polycystic ovary syndrome (PCOS) is associated with hyperandrogenism, and we previously found that androgens activate endoplasmic reticulum (ER) stress in granulosa cells from patients with PCOS. In addition, recent studies demonstrated the accumulation of advanced glycation end products (AGEs) in granulosa cells from PCOS patients, which contribute to the pathology. Therefore, we hypothesized that androgens upregulate the receptor for AGEs (RAGE) expression in granulosa cells by activating ER stress, thereby increasing the accumulation of AGEs in these cells and contributing to the pathology. In the present study, we show that testosterone increases RAGE expression and AGE accumulation in cultured human granulosa-lutein cells (GLCs), and this is reduced by pretreatment with tauroursodeoxycholic acid (TUDCA), an ER stress inhibitor in clinical use. Knockdown of the transcription factor C/EBP homologous protein (CHOP), an unfolded protein response factor activated by ER stress, inhibits testosterone-induced RAGE expression and AGE accumulation. The expression of RAGE and the accumulation of AGEs are upregulated in granulosa cells from PCOS patients and dehydroepiandrosterone-induced PCOS mice. Administration of the RAGE inhibitor FPS-ZM1 or TUDCA to PCOS mice reduces RAGE expression and AGE accumulation in granulosa cells, improves their estrous cycle, and reduces the number of atretic antral follicles. In summary, our findings indicate that hyperandrogenism in PCOS increases the expression of RAGE and accumulation of AGEs in the ovary by activating ER stress, and that targeting the AGE-RAGE system, either by using a RAGE inhibitor or a clinically available ER stress inhibitor, may represent a novel approach to PCOS therapy.

A Japanese nationwide survey on the cryopreservation of embryos, oocytes and ovarian tissue for cancer patients

AIM

The survival rates of cancer patients have greatly improved owing to the advances in oncology. The preservation of fertility in cancer patients is an important task. To determine the reality of cryopreservation of embryos, oocytes and ovarian tissue in cancer patients, large-scale survey analysis was performed in Japan.

METHODS

We sent 613 Japan Society of Obstetrics and Gynecology-certified assisted reproductive technology institutions a questionnaire about their experience of performing cryopreservation for cancer patients between January 2011 and December 2015. Subsequently, the institutions that conducted cryopreservation for cancer patients were sent a second questionnaire.

RESULTS

We received replies from 481 (78.5%) institutions. Among them, 126 (26.2%) conducted cryopreservation for cancer patients. These 126 institutions were sent a second questionnaire. Of these, 108 (85.7%) institutions responded. At the 108 institutions, 1085 embryo or oocyte cryopreservation procedures and 122 ovarian tissue cryopreservation procedures were conducted for cancer patients. Cryopreservation was mainly performed for breast cancer patients (~70%), followed by patients with hematological malignancy. A total of 361 and 19 embryo transfer cycles were performed for patients whose embryos and oocytes were cryopreserved, respectively, and 42 and seven institutions reported pregnancy outcomes after embryo transfer in patients that underwent embryo and oocyte cryopreservation, respectively. However, pregnancy was not observed in the seven cases that underwent ovarian tissue transfer.

CONCLUSION

Indications, age limits and ovarian stimulation protocols for cryopreservation widely varied between the institutions. A national registration system for oncofertility must be established to evaluate the safety and efficacy of the current system.

Endoplasmic Reticulum Stress Activated by Androgen Enhances Apoptosis of Granulosa Cells via Induction of Death Receptor 5 in PCOS

Polycystic ovary syndrome (PCOS) is associated with hyperandrogenism and growth arrest of antral follicles. Previously, we found that endoplasmic reticulum (ER) stress is activated in granulosa cells of antral follicles in PCOS, evidenced by activation of unfolded protein response (UPR) genes. Based on this observation, we hypothesized that ER stress is activated by androgens in granulosa cells of antral follicles, and that activated ER stress promotes apoptosis via induction of the UPR transcription factor C/EBP homologous protein (CHOP) and subsequent activation of death receptor (DR) 5. In this study, we found that testosterone induced expression of various UPR genes, including CHOP, as well as DR5, in cultured human granulosa-lutein cells (GLCs). Pretreatment with the ER stress inhibitor tauroursodeoxycholic acid (TUDCA) inhibited testosterone-induced apoptosis and expression of DR5 and CHOP. Knockdown of CHOP inhibited testosterone-induced DR5 expression and apoptosis, and knockdown of DR5 inhibited testosterone-induced apoptosis. Pretreatment with flutamide, as well as knockdown of androgen receptor, decreased testosterone-induced DR5 and CHOP expression, as well as apoptosis. Expression of DR5 and CHOP was upregulated in GLCs obtained from patients with PCOS, as well as in granulosa cells of antral follicles in ovarian sections obtained from patients with PCOS and dehydroepiandrosterone-induced PCOS mice. Treatment of PCOS mice with TUDCA decreased apoptosis and DR5 expression in granulosa cells of antral follicles, with a concomitant reduction in CHOP expression. Taken together, our findings indicate that ER stress activated by hyperandrogenism in PCOS promotes apoptosis of granulosa cells of antral follicles via induction of DR5.