The telomere theory of reproductive senescence in women

Is it possible that menopause is associated with telomere length? Findings of an integrative review

OBJECTIVE

Knowing the important repercussions of menopause for women's health and that female longevity can be better understood through studies based on aging biomarkers, studies on the relationship between menopause and telomere shortening may help to better understand this stage of life. This study aimed to analyze what research has been produced regarding the relationship between menopause and telomere length.

METHODS

This integrative literature review included searches in PubMed, CINAHL, LILACS, Web of Science and Scopus databases. Four studies were selected for the final sample.

RESULTS

The findings of these studies indicate that older age for menopause and longer reproductive life (difference between age at menopause and menarche) are associated with longer telomeres, that is, with longevity.

CONCLUSION

The relationship between menopause and telomere length is uncertain. The small number of studies included in this review, and the fact that the results indicate that the relationship between menopause and telomere length may be dependent on the stage of the menopause and race/ethnicity, suggest that additional research focusing on these variables should be carried out.

Chromosome ends and the theory of marginotomy: implications for reproduction

Telomeres are the protective structures located at the ends of linear chromosomes. They were first described in the 1930s, but their biology remained unexplored until the early 70s, when Alexey M. Olovnikov, a theoretical biologist, suggested that telomeres cannot be fully copied during DNA replication. He proposed a theory that linked this phenomenon with the limit of cell proliferation capacity and the "duration of life" (theory of marginotomy), and suggested a potential of telomere lenghthening for the prevention of aging (anti-marginotomy). The impact of proliferative telomere shortening on life expectancy was later confirmed. In humans, telomere shortening is counteracted by telomerase, an enzyme that is undetectable in most adult somatic cells, but present in cancer cells and adult and embryonic stem and germ cells. Although telomere length dynamics are different in male and female gametes during gametogenesis, telomere lengths are reset at the blastocyst stage, setting the initial length of the species. The role of the telomere pathway in reproduction has been explored for years, mainly because of increased infertility resulting from delayed childbearing. Short telomere length in ovarian somatic cells is associated to decreased fertility and higher aneuploidy rates in embryos. Consequently, there is a growing interest in telomere lengthening strategies, aimed at improving fertility. It has also been observed that lifestyle factors can affect telomere length and improve fertility outcomes. In this review, we discuss the implications of telomere theory in fertility, especially in oocytes, spermatozoa, and embryos, as well as therapies to enhance reproductive success.

The close relationship between oocyte aging and telomere shortening, and possible interventions for telomere protection

As women delay childbearing due to socioeconomic reasons, understanding molecular mechanisms decreasing oocyte quantity and quality during ovarian aging becomes increasingly important. The ovary undergoes biological aging at a higher pace when compared to other organs. As is known, telomeres play crucial roles in maintaining genomic integrity, and their shortening owing to increased reactive oxygen species, consecutive cellular divisions, genetic and epigenetic alterations is associated with loss of developmental competence of oocytes. Novel interventions such as antioxidant treatments and regulation of gene expression are being investigated to prevent or rescue telomere attrition and thereby oocyte aging. Herein, potential factors and molecular mechanisms causing telomere shortening in aging oocytes were comprehensively reviewed. For the purpose of extending reproductive lifespan, possible therapeutic interventions to protect telomere length were also discussed.

[Replicative and biochemical ageing mechanisms among females with Turner syndromes]

BACKGROUND

2025 is going to be the 100th anniversary of the first historical description of Turner syndrome - complex of  genomic abnormalities, congenital gonadal disruption and hypergonadotropic hypogonadism. Total estrogenic deficiency triggers development of age-related comorbidities. There is no doubt that personalized search for replicative markers of cellular aging among females with Turner syndrome is needed.

AIM

To evaluate features of replicative (telomere length) and biochemical (lipid profile, calcium-phosphate album, thyroid hormones, markers cytolysis and cholestasis, carbohydrate metabolism, nitrogenic metabolism, electrolytes, FSH) markers among females with Turner syndrome.

MATERIALS AND METHODS

Research has been provided in collaboration between Endocrinology Research Centre of the Russian Ministry of Health and Lomonosov Moscow State University Medical Research and Educational Centre in the period since 10.01.2021 until 01.08.2022. Females with non-iatrogenic hypergonadotropic hypogonadism caused by Turner syndrome (45,X0; 45,X/46,XX; 45,X/46,X,r(X); 13-40 y.o.; n=26) and primary ovarian insufficiency (18-39 нyears=26); healthy females of reproductive age (15-49 y.o.; n=24). Patients have undergone laboratory genetic (leucocyte telomere length), biochemical (fasting glycaemia, urea, creatinine, common/conjugated bilirubin, ALT, AST, gamma-glutamyl transferase, triglycerides, HDL-P, LDL-P, common cholesterol, common/ionized calcium, phosphate, vitamin D, sodium/potassium/chlorides, FSH, HbA1c) analyses. Body measurements - body mass, body height. DNA extraction - provided with Qiagen DNA blood mini kit (Germany). Leukocyte telomere length - with real-time polymerase chain reaction PCR (Flow-fish). Soft program IBM SPSS Statistics (version 26,0 for Windows).

RESULTS

1. Females with Turner syndrome have significantly lower mean telomere length (8,22 kB [6,63-9,30]) than with primary ovarian insufficiency (10, 34 кБ [8,41-13,08], p<0,001) and healthy reproductive age females (10,77 kB [9,95-13,16], р>0,05).2. Telomere length correlates directly and significantly with longevity of menopausal hormonal therapy among females with primary ovarian insufficiency (ρ = 505; p<0,001).3. Patients with Turner syndrome are inclined to vitamin D deficiency (р<0,001), dyslipidemia (р=0,01); increase of levels of aminotransferases, cholestasis markers, phosphate and FSH (р<0,001).

CONCLUSION

Turner syndrome is serious genetic disease that leads not only to infertility but to significant decrease of quality/life longevity out of "healthy aging" conception.

The Role of Advanced Parental Age in Reproductive Genetics

The increase of parental reproductive age is a worldwide trend in modern society in recent decades. In general, older parents have a significant impact on reproductive genetics and the health of offspring. In particular, advanced parental age contributes to the increase in the risk of adverse neurodevelopmental outcomes in offspring. However, it is currently under debate how and to what extent the health of future generations was affected by the parental age. In this review, we aimed to (i) provide an overview of the effects of age on the fertility and biology of the reproductive organs of the parents, (ii) highlight the candidate biological mechanisms underlying reproductive genetic alterations, and (iii) discuss the relevance of the effect of parental age on offspring between animal experiment and clinical observation. In addition, we think that the impact of environmental factors on cognitive and emotional development of older offspring will be an interesting direction.

Pathomechanisms of Prenatally Programmed Adult Diseases

Based on epidemiological observations Barker et al. put forward the hypothesis/concept that an adverse intrauterine environment (involving an insufficient nutrient supply, chronic hypoxia, stress, and toxic substances) is an important risk factor for the development of chronic diseases later in life. The fetus responds to the unfavorable environment with adaptive reactions, which ensure survival in the short run, but at the expense of initiating pathological processes leading to adult diseases. In this review, the major mechanisms (including telomere dysfunction, epigenetic modifications, and cardiovascular-renal-endocrine-metabolic reactions) will be outlined, with a particular emphasis on the role of oxidative stress in the fetal origin of adult diseases.

Biomarkers of aging

Aging biomarkers are a combination of biological parameters to (i) assess age-related changes, (ii) track the physiological aging process, and (iii) predict the transition into a pathological status. Although a broad spectrum of aging biomarkers has been developed, their potential uses and limitations remain poorly characterized. An immediate goal of biomarkers is to help us answer the following three fundamental questions in aging research: How old are we? Why do we get old? And how can we age slower? This review aims to address this need. Here, we summarize our current knowledge of biomarkers developed for cellular, organ, and organismal levels of aging, comprising six pillars: physiological characteristics, medical imaging, histological features, cellular alterations, molecular changes, and secretory factors. To fulfill all these requisites, we propose that aging biomarkers should qualify for being specific, systemic, and clinically relevant.

State of the art in assisted reproductive technologies for patients with advanced maternal age

According to the World Health Organization, the female reproductive age lasts up to 49 years, but problems with the realization of women's reproductive rights may arise much earlier. Significant numbers of factors affect the state of reproductive health: socioeconomic, ecological, lifestyle features, the level of medical literacy, and the state of the organization and medical care quality. Among the reasons for fertility decline in advanced reproductive age are the loss of cellular receptors for gonadotropins, an increase in the threshold of sensitivity of the hypothalamic-pituitary system to the action of hormones and their metabolites, and many others. Furthermore, negative changes accumulate in the oocyte genome, reducing the possibility of fertilization, normal development and implantation of the embryo and healthy offspring birth. Another theory of ageing causing changes in oocytes is the mitochondrial free radical theory of ageing. Taking into account all these age-related changes in gametogenesis, this review considers modern technologies aimed at the preservation and realization of female fertility. Among the existing approaches, two main ones can be distinguished: methods allowing the preservation of reproductive cells at a younger age using ART intervention and cryobanking, as well as methods aimed at improving the basic functional state of advanced-age women's oocytes and embryos.

BRCA, infertility, and fertility preservation: a review for counseling

BRCA mutations as a triggering factor in breast cancer have been reported to result in fertility problems and oocyte aging in young patients with cancer diagnosis. These patients are concerned about fertility problems and family planning before undergoing treatment modalities that may result in infertility. In this review, we conducted analysis of the literature on the association between BRCA mutations and infertility, possible fertility preservation options, and their safety and tried to gather results from different disciplines and points of view on the matter. Our aim is to provide a general summary of recent studies to provide further insight on the matter for counseling BRCA mutation carriers on fertility preservation methods and their implications.

Telomere Length and Telomerase Activity of Granulosa Cells and Follicular Fluid in Women Undergoing In Vitro Fertilization

This study aimed to evaluate the interrelationship between telomere length, telomerase activity and oxidative DNA damage in patients undergoing in vitro fertilization (IVF). This single-center, observational clinical study comprised 102 unselected, consecutive patients with various infertility diagnoses. Granulosa cells (GCs) and follicular fluid (FF) were analyzed simultaneously for telomere functions and for the marker of oxidative DNA damage, 8-hydroxy-2-deoxyguanosine (8-OHdG). An Absolute Human Telomere Lengths Quantification qPCR Assay kit and Telomerase Activity Quantification qPCR Assay kit (Nucleotestbio, Budapest, Hungary), as well as an 8-OHdG ELISA kit (Abbexa Ltd., Cambridge, United Kingdom) were used for analyses. Similar telomere lengths were found in GCs and FF, however telomerase activity was markedly depressed, while 8-OHdG levels were markedly elevated in FF compared with those in GCs (p < 0.01). Telomere lengths were independent of telomerase activity both in GCs and FF. However, GC 8-OHdG was inversely related to telomerase activity in GCs and FF (p < 0.05). Importantly, 8-OHdG levels both in GCs and FF had significant negative impact on the number of the retrieved and MII oocytes (p < 0.01), whereas FF 8-OHdG was negatively related further to the number of fertilized oocytes and blastocysts (p < 0.01). In conclusion, we could not confirm the direct association of telomere function and reproductive potential. However, oxidative DNA damage, as mainly reflected by 8-OHdG, adversely affected early markers of IVF outcome and clinical pregnancies.

The Interplay between Telomeres, Mitochondria, and Chronic Stress Exposure in the Aging Egg

While at the organismal level, biological aging can be estimated by telomere length and DNA methylation signatures, reliable biomarkers that can predict reproductive age are much needed to gauge the quality of an oocyte. Reproductive medicine and fertility centers often merely quantitate the ovarian reserve to predict the likelihood of fertilization and pregnancy in women of advanced reproductive age. It is highly important to address the level of age-related decline in oocyte quality since it leads to an increased risk of miscarriages and aneuploidy. Conversely, the pathways behind oocyte aging remain, in large part, elusive. Telomere shortening upon chronic stress exposure regulates mitochondria function and biogenesis by various pathways; therefore, establishing a link between these two important players and extrapolating them for the aging of oocytes will be the purpose of our commentary.

Telomeres, aging and reproduction

PURPOSE OF REVIEW

Women's fertility decay starts at the mid 30 s. However, the current delay of childbearing leads to ovarian aging and the need of assisted reproduction technologies (ART). Telomere biology is one of the main pathways involved in organismal aging. Thus, this review will focus on the knowledge acquired during the last 2 years about the telomere pathway and its influence on female fertility and the consequences for the newborn.

RECENT FINDINGS

New research on telomere biology reaffirms the relationship of telomere attrition and female infertility. Shorter maternal telomeres, which could be aggravated by external factors, underly premature ovarian aging and other complications including preeclampsia, preterm birth and idiopathic pregnancy loss. Finally, the telomere length of the fetus or the newborn is also affected by external factors, such as stress and nutrition.

SUMMARY

Recent evidence shows that telomeres are implicated in most processes related to female fertility, embryo development and the newborn's health. Thus, telomere length and telomerase activity may be good biomarkers for early detection of ovarian and pregnancy failures, opening the possibility to use telomere therapies to try to solve the infertility situation.

Telomeres, oxidative stress, and timing for spontaneous term and preterm labor

Telomeres are nucleoprotein complexes located at the distal ends of chromosomes. In adults, progressive telomere shortening occurs throughout the lifetime and is thought to contribute to progressive aging, physiological senescence, multiorgan dysfunction, and ultimately, death. As discussed in this review, multiple lines of evidence provide support for the biological plausibility that a telomere-based clock mechanism also determines the length of gestation, leading to the onset of labor (parturition). After telomere expansion at the beginning of pregnancy, the telomere lengths in the gestational tissues (ie, the placenta and fetal membranes) progressively shorten throughout the remainder of pregnancy. The rate of telomere shortening can be accelerated by conditions that affect the mother and result in oxidative stress. Preterm births in the United States are associated with multiple risk factors that are linked with increased oxidative stress. Antioxidant vitamins (ie, vitamins E and C) mitigate the effects of oxidative stress and delay or prevent telomere shortening. Clinical trials with vitamins E and C and with multivitamins started during the periconception period have been associated with reduced rates of preterm births. In the United States, African-American women have a 2-3-fold higher rate of preterm birth. African-American women have multiple risk factors for premature birth, all of which are distinct and potentially additive with regard to epigenetic telomere shortening. The "weathering effect" is the hypothesis to explain the increased rates of chronic illness, disabilities, and early death observed in African-Americans. With regard to pregnancy, accelerated weathering with the associated telomere shortening in the gestational tissues would not only explain the preterm birth disparity but could also explain why highly educated, affluent African-American women continue to have an increased rate of preterm birth. These studies suggest that the racial disparities in preterm birth are potentially mediated by telomere shortening produced by lifetime or even generational exposure to the effects of systemic racism and socioeconomic marginalization. In conclusion, this review presents multiple lines of evidence supporting a novel hypothesis regarding the biological clock mechanism that determines the length of pregnancy, and it opens the possibility of new approaches to prevent or reduce the rate of spontaneous preterm birth.

Primary Ovarian Failure in Addition to Classical Clinical Features of Coats Plus Syndrome in a Female Carrying 2 Truncating Variants of CTC1

Coats plus syndrome is an autosomal recessive multisystemic and pleiotropic disorder affecting the eyes, brain, bone, and gastrointestinal tract, usually caused by compound heterozygous variants of the conserved telomere maintenance component 1 gene (CTC1), involved in telomere homeostasis and replication. So far, most reported patients are compound heterozygous for a truncating mutation and a missense variant. The phenotype is believed to result from telomere dysfunction, with accumulation of DNA damage, cellular senescence, and stem cell depletion. Here, we report a 23-year-old female with prenatal and postnatal growth retardation, microcephaly, osteopenia, recurrent fractures, intracranial calcification, leukodystrophy, parenchymal brain cysts, bicuspid aortic valve, and primary ovarian failure. She carries a previously reported maternally inherited pathogenic variant in exon 5 (c.724_727del, p.(Lys242Leufs*41)) and a novel, paternally inherited splice site variant (c.1617+5G>T; p.(Lys480Asnfs*17)) in intron 9. CTC1 transcript analysis showed that the latter resulted in skipping of exon 9. A trace of transcripts was normally spliced resulting in the presence of a low level of wild-type CTC1 transcripts. We speculate that ovarian failure is caused by telomere shortening or chromosome cohesion failure in oocytes and granulosa cells, with early decrease in follicular reserve. This is the first patient carrying 2 truncating CTC1 variants and the first presenting primary ovarian failure.

[Telomere pathology in ontogenesis in patients with Turner syndrome]

According to present medical databases there many trials to provide in vivo researches in vivo to confirm/refute shortening process of telomeres among patients with Turner syndrome. Despite the successful clinical experience of providing such patients with Turner syndrome, a lot of omics (proteomic and metabolomic) aspects still stay unclear. Main disadvantages of most researches are small volume and minimized mathematical correlation with chronic disease (coronary heart disease, essential hypertension, cardiovascular malformations). Finally, organization of international prospective multi-centered researches in vivo including patients with mosaic cariotype and co-operation between physicians and biologists are optimal solutions for this present problem.

Leukocyte Telomere Length Correlates with Extended Female Fertility

Current social trends of delayed reproduction to the fourth and fifth decade of life call for a better understanding of reproductive aging. Demographic studies correlated late reproduction with general health and longevity. Telomeres, the protective ends of eukaryotic chromosomes, were implicated in various aging-associated pathologies and longevity. To examine whether telomeres are also associated with reproductive aging, we measured by Southern analysis the terminal restriction fragments (TRF) in leukocytes of women delivering a healthy infant following a spontaneous pregnancy at 43–48 years of age. We compared them to age-matched previously fertile women who failed to conceive above age 41. The average TRF length in the extended fertility group (9350 bp) was significantly longer than in the normal fertility group (8850 bp; p-value = 0.03). Strikingly, excluding women with nine or more children increased the difference between the groups to over 1000 bp (9920 and 8880 bp; p-value = 0.0009). Nevertheless, we observed no apparent effects of pregnancy, delivery, or parity on telomere length. We propose that longer leukocyte telomere length reflects higher oocyte quality, which can compensate for other limiting physiological and behavioral factors and enable successful reproduction. Leukocyte telomere length should be further explored as a novel biomarker of oocyte quality for assessing reproductive potential and integrating family planning with demanding women’s careers.

The putative roles of FSH and AMH in the regulation of oocyte developmental competence: from fertility prognosis to mechanisms underlying age-related subfertility

BACKGROUND

Fertility loss during female ageing is associated with increasing basal FSH and decreasing anti-Müllerian hormone (AMH) concentrations, together with compromised oocyte quality, presumably due to increased oxidative stress (OS) and DNA damage, as well as reduced metabolic and meiotic competences. Basal FSH and AMH circulatory concentrations have been broadly utilized as IVF success predictors, regardless of fluctuations in prognostic accuracy; basal FSH and AMH perform better in pre-advanced maternal age (AMA: >35 years) and AMA patients, respectively. The relationships between FSH and AMH intrafollicular levels and IVF outcomes suggest, nevertheless, that both hormones regulate oocyte competence, supporting the hypothesis that changes in FSH/AMH levels cause, at least in part, oocyte quality degradation during ageing. To understand the reasons behind the fluctuations in FSH and AMH prognostic accuracies and to clarify their participation in mechanisms determining oocyte competence and age-related subfertility, a deeper knowledge of the regulation of FSH and AMH intrafollicular signalling during the female reproductive lifespan, and of their effects on the cumulus-oocyte complex, is required.

OBJECTIVE AND RATIONALE

An extensive body of information on the regulation of FSH and AMH intrafollicular availability and signalling, as well as on the control of folliculogenesis and oocyte metabolism, has been accumulated. However, these datasets have been explored within the relatively narrow boundaries of their specific subjects. Given the aforementioned gaps in knowledge and their clinical relevance, herein we integrate clinical and basic data, within a wide biological perspective, aiming to shed light on (i) the reasons for the variability in the accuracy of serum FSH and AMH as fertility markers, and on (ii) the potential roles of these hormones in mechanisms regulating oocyte quality, particularly those associated with ageing.

SEARCH METHODS

The PubMed database encompassing the period between 1960 and 2021 was searched. Principal search terms were FSH, FSH receptor, AMH, oocyte, maternal age, cumulus, transzonal projections (TZPs), actin, OS, redox, reactive oxygen species, mitochondria, DNA damage, DNA repair, aneuploidy, spindle, meiosis, gene expression, transcription, translation, oocyte secreted factors (OSFs), cAMP, cyclic guanosine monophosphate, natriuretic peptide C, growth differentiation factor 9, bone morphogenetic protein 15 and fibroblast growth factor.

OUTCOMES

Our analysis suggests that variations in the accuracy of fertility prognosis reflect a modest association between circulatory AMH levels and oocyte quality as well as increasing basal FSH inter-cycle variability with age. In addition, the basic and clinical data articulated herein support the hypothesis that increased intrafollicular FSH levels, as maternal age advances, may override the physiological protective influences of AMH and OSFs against excessive FSH signalling in cumulus cells. This would result in the disruption of oocyte homeostasis via reduced TZP-mediated transfer of cumulus-derived molecules essential for meiotic competence, gene expression, redox activity and DNA repair.

WIDER IMPLICATIONS

In-depth data analysis, encompassing a wide biological perspective has revealed potential causative mechanisms of age-related subfertility triggered by alterations in FSH/AMH signalling during the female reproductive life. Insights from new mechanistic models arising from this analysis should contribute to advancing our comprehension of oocyte biology in humans and serve as a valuable reference for novel AMA subfertility treatments aimed at improving oocyte quality through the modulation of AMH/FSH action.

Ovarian reserve of women with and without BRCA pathogenic variants: A systematic review and meta-analysis

INTRODUCTION

Preliminary clinical evidence suggests a detrimental effect of pathogenic variants of BRCA1 and 2 genes on fertility outcome. This meta-analysis evaluates whether women carrying BRCA mutations (BRCAm) have decreased ovarian reserve, in terms of Anti-Muellerian Hormone (AMH), compared to women without BRCAm (wild-type).

MATERIAL AND METHODS

Systematic searches of PubMed, Medline, Scopus, Embase, Science Direct and the Cochrane Library from inception until July 2020 were conducted. All studies comparing AMH level in fertile age women, with and without BRCA pathogenic variants were considered. Sub-analyses were performed according to age, presence of breast cancer, and type of mutation.

RESULTS

Among 64 studies, 10 series were included. For the entire cohort, a trend of reduced AMH level were found between BRCAm carriers and women without pathogenic variants. BRCAm carriers aged 41-years or younger had lower AMH levels compared to 41-years or younger wild type women (OR: 0.73 [95%CI-1.12;-0.35]; p = 0.0002). This finding was confirmed for BRCA1m carriers (OR: 1 [95%CI-1.96;-0.05]; p = 0.004) whereas no difference was observed between BRCA2m carriers and wild type women. The same analysis on breast cancer patients with and without BRCAm achieved the same results.

CONCLUSION

Young BRCA1m carriers seem to have lower AMH level compared with wild type women and therefore a potential decreased ovarian reserve.

Insights into the Role of Telomeres in Human Embryological Parameters. Opinions Regarding IVF

Telomeres promote genome integrity by protecting chromosome ends from the activation of the DNA damage response and protecting chromosomes from the loss of coding sequences due to the end replication problem. Telomere length (TL) is progressively shortened as age progresses, thus resulting in cellular senescence. Therefore, TL is in strong adverse linear correlation with aging. Mounting evidence supports the notion that telomeres and male/female infertility are in a close relationship, posing the biology of telomeres as a hot topic in the era of human-assisted reproduction. Specifically, the length of sperm telomeres is gradually increasing as men get older, while the telomere length of the oocytes seems not to follow similar patterns with that of sperm. Nonetheless, the telomere length of the embryos during the cleavage stages seems to have a paternal origin, but the telomere length can be further extended by telomerase activity during the blastocyst stage. The latter has been proposed as a new molecular biomarker with strong predictive value regarding male infertility. As far as the role of telomeres in assisted reproduction, the data is limited but the length of telomeres in both gametes seems to be affected mainly by the cause of infertility rather than the assisted reproductive therapy (ART) procedure itself. The present review aims to shed more light into the role of telomeres in human embryological parameters, including gametes and embryos and also presents opinions regarding the association between telomeres and in vitro fertilization (IVF).

Inhibition of LINE-1 retrotransposition represses telomere reprogramming during mouse 2-cell embryo development

PURPOSE

To investigate whether inhibition of LINE-1 affects telomere reprogramming during 2-cell embryo development.

METHODS

Mouse zygotes were cultured with or without 1 µM azidothymidine (AZT) for up to 15 h (early 2-cell, G1/S) or 24 h (late 2-cell, S/G2). Gene expression and DNA copy number were determined by RT-qPCR and qPCR respectively. Immunostaining and telomeric PNA-FISH were performed for co-localization between telomeres and ZSCAN4 or LINE-1-Orf1p.

RESULTS

LINE-1 copy number was remarkably reduced in later 2-cell embryos by exposure to 1 µM AZT, and telomere lengths in late 2-cell embryos with AZT were significantly shorter compared to control embryos (P = 0.0002). Additionally, in the absence of LINE-1 inhibition, Dux, Zscan4, and LINE-1 were highly transcribed in early 2-cell embryos, as compared to late 2-cell embryos (P < 0.0001), suggesting that these 2-cell genes are activated at the early 2-cell stage. However, in early 2-cell embryos with AZT treatment, mRNA levels of Dux, Zscan4, and LINE-1 were significantly decreased. Furthermore, both Zscan4 and LINE-1 encoded proteins localized to telomere regions in 2-cell embryos, but this co-localization was dramatically reduced after AZT treatment (P < 0.001).

CONCLUSIONS

Upon inhibition of LINE-1 retrotransposition in mouse 2-cell embryos, Dux, Zscan4, and LINE-1 were significantly downregulated, and telomere elongation was blocked. ZSCAN4 foci and their co-localization with telomeres were also significantly decreased, indicating that ZSCAN4 is an essential component of the telomere reprogramming that occurs in mice at the 2-cell stage. Our findings also suggest that LINE-1 may directly contribute to telomere reprogramming in addition to regulating gene expression.

Idiopathic early ovarian aging: is there a relation with premenopausal accelerated biological aging in young women with diminished response to ART?

PURPOSE

To evaluate whether young women with idiopathic early ovarian aging, as defined by producing fewer oocytes than expected for a given age over multiple in vitro fertilization (IVF) cycles, have changes in telomere length and epigenetic age indicating accelerated biological aging (i.e., increased risk of morbidity and mortality).

METHODS

A prospective cohort study was conducted at two Danish public fertility clinics. A total of 55 young women (≤ 37 years) with at least two IVF cycles with ≤ 5 harvested oocytes despite sufficient stimulation with follicle-stimulating hormone (FSH) were included in the early ovarian aging group. As controls, 52 young women (≤ 37 years) with normal ovarian function, defined by at least eight harvested oocytes, were included. Relative telomere length (rTL) and epigenetic age acceleration (AgeAccel) were measured in white blood cells as markers of premenopausal accelerated biological aging.

RESULTS

rTL was comparable with a mean of 0.46 (± SD 0.12) in the early ovarian aging group and 0.47 (0.14) in the normal ovarian aging group. The AgeAccel of the early ovarian aging group was, insignificantly, 0.5 years older, but this difference disappeared when adjusting for chronological age. Sub-analysis using Anti-Müllerian hormone (AMH) as selection criterion for the two groups did not change the results.

CONCLUSION

We did not find any indications of accelerated aging in whole blood from young women with idiopathic early ovarian aging. Further investigations in a similar cohort of premenopausal women or other tissues are needed to fully elucidate the potential relationship between premenopausal accelerated biological aging and early ovarian aging.

Preconception leukocyte telomere length and pregnancy outcomes among women with demonstrated fecundity

STUDY QUESTION

Is preconception leukocyte telomere length associated with fecundability, pregnancy loss and live birth among women attempting natural conception with a history of 1-2 prior pregnancy losses?

SUMMARY ANSWER

Preconception leukocyte telomere length is not associated with fecundability, pregnancy loss or live birth.

WHAT IS KNOWN ALREADY

As women increasingly delay childbearing, accessible preconception biomarkers to predict pregnancy outcomes among women seeking natural conception could improve preconception counseling. Findings of small case-control or cross-sectional studies suggest that telomere attrition is associated with adverse pregnancy outcomes among women undergoing fertility treatment, but prospective studies in non-clinical populations are lacking.

STUDY DESIGN, SIZE, DURATION

Participants included 1228 women aged 18-40 years with a history of 1-2 prior pregnancy losses who were recruited at four university medical centers (2006-2012).

PARTICIPANTS/MATERIALS, SETTING, METHODS

Preconception leukocyte telomere length was measured at baseline using PCR and reported as a ratio (T/S) in relation to population-specific standard reference DNA. Women were followed for up to six cycles while attempting to conceive. Associations of telomere length with fecundability, live birth and pregnancy loss were estimated using discrete Cox proportional hazards models and log-binomial models.

MAIN RESULTS AND THE ROLE OF CHANCE

After adjustment for age, BMI, smoking and other factors, preconception telomere length was not associated with fecundability (Q4 vs Q1 FOR = 1.00; 95% CI = 0.79, 1.27), live birth (Q4 vs Q1 RR = 1.00; 95% CI = 0.85, 1.19), or pregnancy loss (Q4 vs Q1 RR = 1.12; 95% CI = 0.78, 1.62).

LIMITATIONS, REASONS FOR CAUTION

Telomere length was measured in leukocytes, which is an accessible tissue in women attempting natural conception but may not reflect telomere length in oocytes. Most women were younger than 35 years, limiting our ability to evaluate associations among older women. Participants had a history of 1-2 prior pregnancy losses; therefore, our findings may not be widely generalizable.

WIDER IMPLICATIONS OF THE FINDINGS

Despite prior research suggesting that telomere length may be associated with pregnancy outcomes among women seeking fertility treatment, our findings suggest that leukocyte telomere length is not a suitable biomarker of pregnancy establishment or maintenance among women attempting natural conception.

STUDY FUNDING/COMPETING INTEREST(S)

This research was supported by the Intramural Research Program of the Eunice Kennedy Shriver National Institute of Child Health and Human Development (National Institutes of Health, Bethesda, MD, USA; contract numbers HHSN267200603423, HHSN267200603424 and HHSN267200603426). The authors have no conflicts of interest to disclose.

TRIAL REGISTRATION NUMBER

The trial was registered with ClinicalTrials.gov, number NCT00467363.

Endometriosis and Uterine Fibroids and Their Associations with Elevated C-Reactive Protein and Leukocyte Telomere Length Among a Representative Sample of U.S. Women: Data from the National Health and Nutrition Examination Survey, 1999-2002

Background: Recent studies have suggested a link between reproductive health and later-life chronic conditions, yet the mechanism remains unclear. One proposed mechanism is through chronic inflammation. The objective of this study was to examine the association between endometriosis and uterine fibroids and biomarkers of inflammation and cellular aging. Materials and Methods: We used data from the National Health and Nutrition Examination Survey (N = 2342; 1999-2002). Adjusted logistic and linear regression were used to examine the association between these two reproductive conditions and elevated C-reactive protein (CRP; >3.0 mg/L) and leukocyte telomere length (T/S ratio), respectively. Given that a greater length of time spent with a condition may represent persistence of an inflammatory process, we further examined the association between time since disease diagnosis on telomere length among the subset of women with diagnosed endometriosis and fibroids. Results: Women with endometriosis had greater odds of having elevated CRP than those without endometriosis (OR = 1.60; 95% CI: 1.05 to 2.45). Women with endometriosis had a shorter telomere length than women without endometriosis (-3.4, 95% CI: -7.3 to -0.3 in age-adjusted models and -2.9, 95% CI: -8.8 to 3.5 in fully adjusted models). Telomeres were 1% (95% CI: -1.2 to -0.6) shorter for every elapsed year since endometriosis diagnosis. No substantive patterns emerged between uterine fibroids and CRP or telomere length. Conclusions: Women with endometriosis (or a longer duration of time spent with endometriosis) had higher inflammatory markers and shorter mean telomere length. These results provide further insights into potential mechanisms linking endometriosis to chronic disease and later-life health.

Factors Affecting Artificial Insemination Pregnancy Outcome

Objective

The aim of the present study was to explore related clinical pregnancy outcome factors in intrauterine insemination (IUI).

Materials and Methods

The clinical data of 3984 IUI cycles in 1862 couples experiencing infertility who attended the Reproductive Center of Binzhou Medical University Hospital between July 2006 and July 2017 were retrospectively analyzed. Female and male patient age, endometrial thickness (EMT), the post-wash total motile sperm count (PTMC), artificial insemination timing, insemination frequency, and ovarian stimulation protocols were compared between the study’s pregnant group and non-pregnant group in order to explore any correlation.

Results

There were statistically significant differences in female and male age, EMT, artificial insemination timing, insemination frequency, and ovarian stimulation protocols between the two groups (p < 0.05). The clinical pregnancy rate was significantly higher in ovarian stimulation cycles than in natural cycles (21.2% and 11.6%, respectively; p < 0.01), the clinical pregnancy rate was significantly higher in double IUI than in single IUI (17.8% and 12.1%, respectively; p < 0.01), and EMT was significantly greater in the pregnant group than in the control group (p < 0.05). However, the differences in clinical pregnancy rates among the PTMC groups were not statistically significant (14.8%, 14.4%, 17.3%, and 17.3%, respectively; p > 0.05).

Conclusion

The results of the present study demonstrate that the clinical IUI pregnancy rate is correlated with the factors of female age, male age, EMT, artificial insemination timing, insemination frequency, and ovarian stimulation protocols; the ovarian stimulation protocol can noticeably improve the patient pregnancy outcome. Furthermore, compared with single IUI, double IUI can significantly increase the clinical pregnancy rate.

Oxidative Stress Induces Telomere Dysfunction and Shortening in Human Oocytes of Advanced Age Donors

Research from the past decades provided strong evidence that in humans the pool of oocytes starts to decline already before the birth of a female individual, and from menarche to menopause the oocyte is exposed to different environmental stimuli. Since more and more women of the 21st century in developed countries wish to postpone the first pregnancy to their thirties, higher rates of miscarriage and chromosomal non-disjunction might occur. In oocytes of advanced maternal age, meaning above 35 years of age, characteristics such as chromosomal instabilities/abnormalities, spindle defects, decreased mitochondrial function and telomere shortening become more prevalent than in younger counterparts. Telomere attrition belongs to the so-called “hallmarks of aging” which are also relevant for the female germ-line cells. In oocytes, telomeres shorten with advancing maternal age due to the effects of reactive oxygen species and not upon replicative senescence, similar to how it is common in dividing cells.

Ovarian Telomerase and Female Fertility

Women's fertility is characterized both quantitatively and qualitatively mainly by the pool of ovarian follicles. Monthly, gonadotropins cause an intense multiplication of granulosa cells surrounding the oocyte. This step of follicular development requires a high proliferation ability for these cells. Telomere length plays a crucial role in the mitotic index of human cells. Hence, disrupting telomere homeostasis could directly affect women's fertility. Strongly expressed in ovaries, telomerase is the most effective factor to limit telomeric attrition and preserve ovarian reserve. Considering these facts, two situations of infertility could be correlated with the length of telomeres and ovarian telomerase activity: PolyCystic Ovary Syndrome (PCOS), which is associated with a high density of small antral follicles, and Premature Ovarian Failure (POF), which is associated with a premature decrease in ovarian reserve. Several authors have studied this topic, expecting to find long telomeres and strong telomerase activity in PCOS and short telomeres and low telomerase activity in POF patients. Although the results of these studies are contradictory, telomere length and the ovarian telomerase impact in women's fertility disorders appear obvious. In this context, our research perspectives aimed to explore the stimulation of ovarian telomerase to limit the decrease in the follicular pool while avoiding an increase in cancer risk.

Reproductive aging and telomeres: Are women and men equally affected?

Successful reproduction is very important for individuals and for society. Currently, the human health span and lifespan are the object of intense and productive investigation with great achievements, compared to the last century. However, reproduction span does not progress concomitantly with lifespan. Reproductive organs age, decreasing the levels of sexual hormones, which are protectors of health through their action on several organs of the body. Thus, this is the starting point of the organismal decay and infertility. This starting point is easily detected in women. In men, it goes under the surface, undetected, but it goes, nevertheless. Regarding fertility, aging alters the hormonal equilibrium, decreases the potential of reproductive organs, diminishes the quality of the gametes and worsen the reproductive outcomes. All these events happen at a different pace and affecting different organs in women and men. The question is what molecular pathways are involved in reproductive aging and if there is a possible halting or even reversion of the aging events. Answers to all these points will be explained in the present review.

Telomere Shortening and Fusions: A Link to Aneuploidy in Early Human Embryo Development

Importance

It is known that oocytes undergo aging that is caused by exposure to an aged ovarian microenvironment. Telomere length in mouse and bovine oocytes declines with age, and age-associated telomere shortening in oocytes is considered a sign of poor development competency. Women with advanced age undergoing assisted reproductive technologies have poor outcomes because of increasing aneuploidy rates with age. Research has shown that aneuploidy is associated with DNA damage, reactive oxygen species, and telomere dysfunction.

Objective

In this review, we focus on the possible relationship between telomere dysfunction and aneuploidy in human early embryo development and several reproductive and perinatal outcomes, discussing the mechanism of aneuploidy caused by telomere shortening and fusion in human embryos.

Evidence Acquisition

We reviewed the current literature evidence concerning telomere dysfunction and aneuploidy in early human embryo development.

Results

Shorter telomeres in oocytes, leukocytes, and granulosa cells, related to aging in women, were associated with recurrent miscarriage, trisomy 21, ovarian insufficiency, and decreasing chance of in vitro fertilization success. Telomere length and telomerase activity in embryos have been related to the common genomic instability at the cleavage stage of human development. Complications of assisted reproductive technology pregnancies, such as miscarriage, birth defects, preterm births, and intrauterine growth restriction, also might result from telomere shortening as observed in oocytes, polar body, granulosa cells, and embryos.

Conclusions and Relevance

Telomere length clearly plays an important role in the development of the embryo and fetus, and the abnormal shortening of telomeres is likely involved in embryo loss during early human development. However, telomere fusion studies have yet to be performed in early human development.

Searching for female reproductive aging and longevity biomarkers

Female reproductive aging is, in a way, a biological phenomenon that develops along canonical molecular pathways; however, it has particular features. Recent studies revealed complexity of the interconnections between reproductive aging and aging of other systems, and even suggested a cause-effect uncertainty between them. It was also shown that reproductive aging can impact aging processes in an organism at the level of cells, tissues, organs, and systems. Women at the end of their reproductive lives are characterized by the accelerated incidence of age-related diseases. Timing of the onset of menarche and menopause and variability in the duration of reproductive life carry a latent social risk: not having enough information about the reproductive potential, women keep on postponing childbirth. Identification and use of the most accurate and sensitive aging biomarkers enable the prediction of menopause timing and quantification of the true biological and reproductive ages of an organism. We discuss current views on reproductive aging and peculiarities of using available biomarkers of aging. We also consider latest advances in the search for potential genetic markers of reproductive aging. Finally, we posit the importance of determining the female biological age and highlight potential research directions in this area.

Comparative study of assisted reproductive outcomes between young patients with occult premature ovarian insufficiency and advanced-age patients

Objective

The purpose of this study was to compare the pregnancy outcomes among young patients with occult premature ovarian insufficiency (OPOI), advanced-age patients with diminished ovarian reserve (DOR), and advanced-age patients with normal ovarian reserve.

Methods

We retrospectively reviewed 324 women who underwent their first cycles of in vitro fertilization/intracytoplasmic sperm injection. The women were divided into the following groups: young women with OPOI, advanced-age women with DOR, and advanced-age women with normal ovarian reserve. The outcomes were compared among the different groups:

Results

The rates of live birth and embryo implantation in the young OPOI group were significantly higher than in the advanced-age DOR group, but comparable to those in the advanced-age normal ovarian reserve group. Moreover, the abortion rate was significantly lower in young OPOI patients compared with advanced-age patients with or without DOR.

Conclusion

Higher embryo implantation and live birth rates and a lower abortion rate can be achieved in young patients with OPOI compared with older patients. The better outcomes in advanced-age patients with normal ovarian reserve compared with DOR may be related to egg quantity rather than quality.

Maternal age at last birth and leukocyte telomere length in a nationally representative population of perimenopausal and postmenopausal women

OBJECTIVE

The primary aim of this study was to evaluate if maternal age at birth of last child is associated with leukocyte telomere length in a nationally representative population of perimenopausal and postmenopausal women.

METHODS

We conducted a cross-sectional analysis of 1,232 women from the National Health and Nutrition Examination Survey to examine maternal age at last birth and telomere length, surveyed between 1999 and 2002. We included perimenopausal and postmenopausal women age 40 years and older. Maternal age at last live birth was self-reported, and leukocyte telomere length was measured using quantitative polymerase chain reaction. We calculated least-squares geometric mean telomere length across categories of maternal age adjusted for age, race/ethnicity, number of live births, survey cycle, and history of hysterectomy or oophorectomy. P trend < 0.05 was considered statistically significant. For hypothesis-generation, we explored modification by reproductive and sociodemographic factors.

RESULTS

Maternal age at last birth was positively associated with telomere length: the multivariable-adjusted least-squares geometric mean leukocyte telomere length across categories of age at last birth (<25, 25-29, 30-34, 35-39, ≥40 y) was 0.90, 0.93, 0.93, 0.95, and 0.96, respectively (P trend = 0.04). There was suggestive evidence this association may be restricted to those women with one or two live births or women who reported ever using oral contraceptives (P interaction <0.10 for both).

CONCLUSIONS

Later maternal age was associated with longer telomere length in a nationally representative population of women. These data provide new insight into the biological relationship between reproductive history and long-term health. : Video Summary:http://links.lww.com/MENO/A662.

Hypothalamic aging and hormones

It is the heterogeneous changes of hypothalamic functions that determine the chronological sequence of aging in mammals. Recently, it was hypothesized by Cai the decrease in slow-wave sleep (SWS) resulting from skin aging as responsible for the degeneration of hypothalamic suprachiasmatic nucleus (SCN). It was soon hypothesized by the European people in television that the increase in body fat as responsible for the degeneration of male preoptic sexually dimorphic nucleus (SDN-POA), via the aromatase converting testosterone to estradiol as proposed by Cohen. It is the hypothalamic paraventricular nucleus (PVN) that remains unchanged in neuron number during aging for psychological stress. In this chapter, it is briefly reviewed more manifestations of hypothalamic related mammalian aging processes, including (1) the aging of ovary by lipid, estradiol and hypothalamus; (2) the aging of muscle, stomach, intestine, thymus, and the later aging of brain, regulated by growth hormone/insulin-like growth factor 1(GH/IGF1); (3) the cardiovascular hypertension from PVN activation, the bone and other peripheral aging by psychological stress, and that of kidney by vasopressin. It is classified these aging processes by the primary regulation from one of the three hypothalamic nuclei, although still necessary to investigate and supplement their secondary regulation by the hypothalamic nuclei in future. It is the hypothalamic structural changes that shift the functional balance among these three hypothalamic systems toward aging.

Value of serum and follicular fluid sirtuin (SIRT)1 and SIRT2 protein levels in predicting the outcome of assisted reproduction

Background

To explore whether serum and follicular fluid (FF), sirtuin 1 (SIRT1), and SIRT2 could predict the outcome of assisted reproduction.

Methods

All patients underwent in vitro fertilization (IVF)/intracytoplasmic sperm injection (ICSI) for the first time in the Reproductive Medicine Center of the First Affiliated Hospital of Zhejiang University Medical College from March 2018 to December 2018. According to cumulative clinical pregnancy outcomes, the patients were divided into a pregnancy group and non-pregnancy group. We measured the serum levels of SIRT1, SIRT2, anti-Müllerian hormone (AMH), follicle-stimulating hormone (FSH), luteinizing hormone (LH), and estradiol (E2) from the second to the fifth day of menstruation, and the levels of SIRT1 and SIRT2 in serum and FF on the day of human chorionic gonadotropin (HCG) injection and oocyte retrieval.

Results

A total of 125 patients met the inclusion criteria. The pregnancy group comprised 56 cases and non-pregnancy group 69 cases. There were significant differences in basal level SIRT2 (bSIRT2), AMH, antral follicle count (AFC), number of oocytes obtained, number of mature eggs, number of fertilized eggs, number of excellent embryos, number of blastocyst formations, and number of transferred high-quality embryos between the two groups. The area under the curve (AUC) values of bSIRT2, AFC, AMH, and age were significantly different from those under the opportunity reference line (P<0.05). In the subsequent correlation analysis, FFSIRT2, and HCG day serum SIRT2 were negatively correlated with age (r=−0.35, r=−0.19), and positively correlated with AFC (r=0.2, r=0.02). Serum SIRT1 on HCG day was negatively correlated with the number of blastocysts and the number of frozen embryos (r=−0.18, r=−0.21). Levels of FF SIRT1 and FF SIRT2 were significantly lower than those in serum SIRT1 and SIRT2, and there was no significant difference in serum SIRT1 and SIRT2 before and after ovulation promotion.

Conclusions

The results suggest that bSIRT2 has significant statistical significance in predicting the cumulative number of pregnancies. When combined with AMH, AFC, and age, bSIRT2 can predict the cumulative pregnancy outcome. In addition, the level of serum SIRT1 and SIRT2 were not affected by ovulation promotion.

Telomere length is not altered in girls with idiopathic central precocious puberty treated with a GnRH analog - leuprolide acetate

BACKGROUND

Idiopathic central precocious puberty (iCPP) presents a disproportionate advancement of bone age and maturation, as well as metabolic and endocrinological changes that may be related to effects on telomere biology.

OBJECTIVE

To investigate the telomere length in iCPP girls treated with GnRHa.

STUDY DESIGN

Observational case-control study with 85 girls, including 45 iCPP treated with GnRHa and 40 controls. It was analyzed age, height, weight and body mass index (BMI), insulin, triglycerides, testosterone, insulin resistance by HOMA, and telomere length by real-time PCR. Statistical analyses were determined by Wilcoxon test and Spearman correlation was carried out.

RESULTS

Weight, BMI, insulin level and HOMA index were higher in the iCPP than in the control group (p < .01); without difference between mean ages. The telomere length did not differ between iCPP and control group. However, a negative correlation was observed between the telomere length and age in iCPP (p = .0009) and control group (p = .014), and weight in the iCPP (p = .017).

CONCLUSIONS

We did not observe any difference in the telomere length in the iCPP and control group. Even though, some characteristics of the disease, such as increased weight and body fat, negatively influence the telomere biology.

Decreased expression of TERT and telomeric proteins as human ovaries age may cause telomere shortening

OBJECTIVE

Telomeres are repetitive sequences localized at the ends of eukaryotic chromosomes comprising noncoding DNA and telomere-binding proteins. TRF1 and TRF2 both bind to the double-stranded telomeric DNA to regulate its length throughout the lifespan of eukaryotic cells. POT1 interacts with single-stranded telomeric DNA and contributes to protecting genomic integrity. Previous studies have shown that telomeres gradually shorten as ovaries age, coinciding with fertility loss. However, the molecular background of telomere shortening with ovarian aging is not fully understood.

METHODS

The present study aimed to determine the spatial and temporal expression levels of the TERT, TRF1, TRF2, and POT1 proteins in different groups of human ovaries: fetal (n = 11), early postnatal (n = 10), premenopausal (n = 12), and postmenopausal (n = 14). Also, the relative telomere signal intensity of each group was measured using the Q-FISH method.

RESULTS

We found that the telomere signal intensities decreased evenly and significantly from fetal to postmenopausal groups (P < 0.05). The TERT, TRF1, TRF2, and POT1 proteins were localized in the cytoplasmic and nuclear regions of the oocytes, granulosa and stromal cells. Furthermore, the expression levels of these proteins reduced significantly from fetal to postmenopausal groups (P < 0.05).

CONCLUSION

These findings suggest that decreased TERT and telomere-binding protein expression may underlie the telomere shortening of ovaries with age, which may be associated with female fertility loss. Further investigations are required to elicit the molecular mechanisms regulating the gradual decrease in the expression of TERT and telomere-binding proteins in human oocytes and granulosa cells during ovarian aging.

The effect of rapamycin on bovine oocyte maturation success and metaphase telomere length maintenance

Maternal aging-associated reduction of oocyte viability is a common feature in mammals, but more research is needed to counteract this process. In women, the first aging phenotype appears with a decline in reproductive function, and the follicle number gradually decreases from menarche to menopause. Cows can be used as a model of early human embryonic development and reproductive aging because both species share a very high degree of similarity during follicle selection, cleavage, and blastocyst formation. Recently, it has been proposed that the main driver of aging is the mammalian target of rapamycin (mTOR) signaling rather than reactive oxygen species. Based on these observations, the study aimed to investigate for the first time the possible role of rapamycin on oocyte maturation, embryonic development, and telomere length in the bovine species, as a target for future strategies for female infertility caused by advanced maternal age. The 1nm rapamycin in vitro treatment showed the best results for maturation rates (95.21±4.18%) of oocytes and was considered for further experiments. In conclusion, rapamycin influenced maturation rates of oocytes in a concentration-dependent manner. Our results also suggest a possible link between mTOR, telomere maintenance, and bovine blastocyst formation.

Preconception resveratrol intake against infertility: Friend or foe?

BACKGROUND

Resveratrol is an antiaging, antioxidant, anti-inflammatory, and insulin-sensitizing natural polyphenolic compound. Growing evidence indicates that resveratrol has potential therapeutic effects in infertile women with diminished ovarian function, polycystic ovary syndrome (PCOS), or endometriosis. However, only one clinical trial in women undergoing in vitro fertilization (IVF) cycles using resveratrol has ever been reported. This review focuses on the potential therapeutic effects of resveratrol on pregnancy and on its advantages and disadvantages in pregnancy outcomes during infertility treatment.

METHODS

We performed a literature review to describe the known impacts of resveratrol on the ovary and endometrium.

RESULTS

Resveratrol upregulates sirtuin (SIRT)1 expression in ovaries, which is associated with protection against oxidative stress. It leads to the activation of telomerase activity and mitochondrial function, improving ovarian function. In the endometrium, resveratrol downregulates the CRABP2-RAR pathway leading to suppressing decidual and senescent changes of endometrial cells, which is essential for embryo implantation and placentation. Moreover, resveratrol may also induce deacetylation of important decidual-related genes.

CONCLUSIONS

Resveratrol has potential therapeutic effects for improving ovarian function; however, it also has anti-deciduogenic actions in uterine endometrium. In addition, its teratogenicity has not yet been ruled out; thus, resveratrol should be avoided during the luteal phase and pregnancy.

Increasing telomerase enhanced steroidogenic genes expression and steroid hormones production in rat and human granulosa cells and in mouse ovary

Telomerase, a ribonucleoprotein responsible for telomere re-elongation, is important for male and female fertility. Several factors, including the steroid hormone estrogen, regulate the expression of Telomerase Reverse Transcriptase (TERT), which one of its non-canonical functions is gene expression regulation. The steroidogenesis process is regulated principally by transcription of genes encoding steroidogenic enzymes, but it is not clear if TERT non-canonical functions affect the expression of steroidogenic genes. Here we investigated this new notion by increasing TERT expression and activity in granulosa cells (GCs) derived from rat and from women that underwent in vitro fertilization (IVF) procedures and in vivo in mouse ovary. We show that gonadotropin enhanced the expression of TERT in rat GCs. Overexpression of human- TERT enhanced the expression of steroidogenesis genes in gonadotropin-stimulated rat GCs. Moreover, treatment with TERT increasing compounds (AGS) alone enhanced the expression of the steroidogenic genes in both rat and human GCs and in vivo in mouse ovary, while telomerase inhibitor reduced their expression. Treatment with AGS compounds, together with gonadotropin stimulation, additively increased steroidogenic gene expression. Enhancing TERT expression and activity increased the level of progesterone in mouse blood and in the medium of rat GCs and estrogen in women derived pre-ovulatory luteinized GCs. These data suggest that increasing TERT in GCs by pharmaceutical compounds enhanced steroidogenesis and the production of steroid hormones that are essential processes in human and animal reproduction. These data also suggest a novel possible strategy for the enhancement of the production of steroid hormones.

Melatonin as Potential Targets for Delaying Ovarian Aging

In previous studies, oxidative stress damage has been solely considered to be the mechanism of ovarian aging, and several antioxidants have been used to delay ovarian aging. But recently, more reports have found that endoplasmic reticulum stress, autophagy, sirtuins, mitochondrial dysfunction, telomeres, gene mutation, premature ovarian failure, and polycystic ovary syndrome are all closely related to ovarian aging, and these factors all interact with oxidative stress. These novel insights on ovarian aging are summarized in this review. Furthermore, as a pleiotropic molecule, melatonin is an important antioxidant and used as drugs for several diseases treatment. Melatonin regulates not only oxidative stress, but also the various molecules, and normal and pathological processes interact with ovarian functions and aging. Hence, the mechanism of ovarian aging and the extensive role of melatonin in the ovarian aging process are described herein. This systematic review supply new insights into ovarian aging and the use of melatonin to delay its onset, further supply a novel drug of melatonin for ovarian aging treatment.

Telomere Length and Telomerase Activity in Immature Oocytes and Cumulus Cells of Women with Polycystic Ovary Syndrome

Metaphase II oocytes (MII) from polycystic ovary syndrome (PCOS) frequently have impaired oocyte competence. Since telomere maintenance is important for folliculogenesis, oocyte maturation, and early embryonic development, we sought to verify the implications of PCOS on telomere length and telomerase activity in immature oocytes and cumulus cells. 43 PCOS and 67 control women were included, and anthropometric, biochemical, and hormonal characteristics were evaluated. The telomere length in germinal vesicle stage (GV) and in metaphase I (MI) oocytes, as well as in the cumulus cells of immature (CCI) and mature oocytes (CCM), and in leukocytes was measured by qPCR. The telomerase activity in reproductive cells was evaluated by the TRAPeze® XL Kit. The body mass index (p = 0.001), LH (p = 0.015), estradiol (p = 0.004), insulin (p = 0.002), testosterone (p < 0.0001), androstenedione (p = 0.001), free androgen index (p < 0.0001), and c-reactive protein (p = 0.003) were greater, while the FSH (p = 0.0002) was lower in the PCOS group. The telomere length in the CCI (p = 0.649) and CCM (p = 0.378) did not differ between the PCOS and the control groups. On the other hand, telomerase activity in the CCI (p = 0.003) and CCM (p = 0.022) was higher in the PCOS group. In the leukocyte's cells, the telomere length was reduced in the PCOS group (p = 0.025). In the GV and MI oocytes, no differences were observed in telomere length and telomerase activity between the groups. We showed that telomere length is not altered in reproductive cells from PCOS. However, higher telomerase activity in the CCI and CCM may be required for telomere length maintenance.

DNA damage in aging, the stem cell perspective

DNA damage is one of the most consistent cellular process proposed to contribute to aging. The maintenance of genomic and epigenomic integrity is critical for proper function of cells and tissues throughout life, and this homeostasis is under constant strain from both extrinsic and intrinsic insults. Considering the relationship between lifespan and genotoxic burden, it is plausible that the longest-lived cellular populations would face an accumulation of DNA damage over time. Tissue-specific stem cells are multipotent populations residing in localized niches and are responsible for maintaining all lineages of their resident tissue/system throughout life. However, many of these stem cells are impacted by genotoxic stress. Several factors may dictate the specific stem cell population response to DNA damage, including the niche location, life history, and fate decisions after damage accrual. This leads to differential handling of DNA damage in different stem cell compartments. Given the importance of adult stem cells in preserving normal tissue function during an individual's lifetime, DNA damage sensitivity and accumulation in these compartments could have crucial implications for aging. Despite this, more support for direct functional effects driven by accumulated DNA damage in adult stem cell compartments is needed. This review will present current evidence for the accumulation and potential influence of DNA damage in adult tissue-specific stem cells and propose inquiry directions that could benefit individual healthspan.

Longitudinal analysis of somatic and germ-cell telomere dynamics in outbred mice

Although telomere length (TL) shortens with age in most tissues, an age-related increase in length has been described in sperm through a mechanism that is not yet fully understood. Changes in TL with age in the same individual have not been explored. This longitudinal study examines TL dynamics in somatic tissue and gametes during an entire lifespan in an outbred mouse population (from 8 to up to 114 weeks of age). Our findings indicate a reduced life expectancy in males compared to females (84.75 ± 9.23 vs. 113.16 ± 0.20 weeks) and significant variability in TL dynamics between individuals. While with aging, a clear reduction in TL was produced in somatic cells and oocytes, telomeres in sperm cells significantly lengthened. Finally, we found evidence indicating that telomere elongation in sperm during aging may be dependent on different mechanisms, such as the survival of spermatogonia with longer telomeres and the alternative lengthening of telomeres mechanism in meiotic and postmeiotic spermatogenic cells.

Telomeres and genomic instability during early development

Genomic instability is widespread during early embryo development. Aneuploidy, mosaicism, and copy number variants (CNVs) commonly appear in human preimplantation embryos. Both age-dependent meiotic aneuploidy and age-independent mitotic aneuploidy and CNVs occur In human embryos. Telomere attrition, which contributes to genomic instability in somatic cells, also may promote genomic instability in preimplantation embryos. Telomere dynamics during gametogenesis are strikingly dimorphic between females and males. Sperm telomeres lengthen with advancing paternal age, while oocyte telomeres are among the shortest in the body. Spermatogonia express telomerase activity throughout the life of the male, while oocytes and cleavage stage embryos express low or un-measureable levels of telomerase activity. Telomere attrition in oocytes contributes to meiotic dysfunction, including spindle dysmorphologies, reduced synapsis and chiasmata, as well as delayed, arrested and fragmented embryos. Cleavage stage embryos, with such inefficient telomere reconstitution, likely undergo NHEJ, which produces anaphase lag, chromosome bridges, micronuclei, and genomic instability, including mosaicism and CNVs. Cleavage stage embryos reconstitute the short telomeres inherited from their mothers by Alternative Lengthening of Telomeres (ALT), a DNA recombination based method involving RAD 50, MRE 11, Werner and Bloom proteins, as well as telomere sister chromatid exchange. ALT robustly reconstitutes telomeres, but also predisposes to genomic instability.

Skewed X-chromosome inactivation and shorter telomeres associate with idiopathic premature ovarian insufficiency

OBJECTIVE

To analyze whether telomere length, X-chromosome inactivation (XCI), and androgen receptor (AR) GAG polymorphism are related to idiopathic premature ovarian insufficiency (POI).

DESIGN

Case-control study.

SETTING

University hospital.

PATIENT(S)

A total of 121 women, including 46 nonsyndromic POI and 75 controls.

INTERVENTION(S)

None.

MAIN OUTCOME MEASURE(S)

Age, weight, height, body mass index (BMI), systolic and diastolic arterial pressure, E₂, androstenedione, T, and C-reactive protein were assessed. Telomere length was estimated by quantitative real-time polymerase chain reaction, XCI was measured using the Human Androgen Receptor and X-linked retinitis pigmentosa 2 (RP2) methylation assays. AR and FMR1 polymorphism was assessed by quantitative fluorescent polymerase chain reaction and sequencing.

RESULT(S)

Premature ovarian insufficiency women had a higher mean age, weighed less, and exhibited lower C-reactive protein, E₂, and androstenedione levels. The AR polymorphism did not differ between the groups. Four patients had premutation (55-200 CGG repeats), and none displayed a full mutation in the FMR1 gene. However, patients with POI showed shorter telomere length and higher frequency of skewed XCI. Extreme skewing (≥90%) was observed in 15% of women with POI, and shorter telomeres correlated with XCI skewing in both groups.

CONCLUSION(S)

Skewed XCI and shortened telomere length were associated with idiopathic POI, despite no alterations in the AR and FMR1 genes. Additionally, there is a tendency for women with short telomeres to exhibit skewed XCI.

Direct Single-Cell Analysis of Human Polar Bodies and Cleavage-Stage Embryos Reveals No Evidence of the Telomere Theory of Reproductive Ageing in Relation to Aneuploidy Generation

Reproductive ageing in women, particularly after the age of 35, is associated with an exponential increase in the proportion of chromosomally abnormal oocytes produced. Several hypotheses have attempted to explain this observation, including the 'limited oocyte pool' hypothesis and the 'two-hit' hypothesis, the latter explaining that a depletion in oocyte quality with age results from the multiple opportune stages for errors to occur in meiosis. Recently however, the telomere theory of reproductive ageing in women has been proposed. This suggests that shortened telomeres in oocytes of women of advanced maternal age render oocytes unable to support fertilization and embryogenesis. Despite a credible rationale for the telomere theory of reproductive ageing in women, very few studies have assessed telomere length directly in human oocytes or preimplantation embryos. Therefore, we directly assessed relative telomere length in first polar bodies and blastomeres from cleavage stage (day 3) embryos. In both cell types we tested the hypothesis that (1) older women have shorter telomeres and (2) chromosomally abnormal (aneuploid) gametes/embryos have shorter telomeres. In all cases, we found no evidence of altered telomere length associated with age-related aneuploidy.